Latest / Deep Dive Ortho — Orthopaedic Surgery, AI & Digital Health Podcast. / ACL Rupture

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ACL Rupture · Deep Dive Ortho — Orthopaedic Surgery, AI & Digital Health Podcast.

0:00
Welcome to The Deep Dive, the show where we really
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get into the sources, the research, the articles,
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the notes, to bring you the essential insights,
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maybe some surprising facts, and enough context
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so you feel properly informed, but not swamped
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in technical terms. Exactly. Today, we are tackling
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something that crops up far too often, particularly
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if you're involved in sports in any way, injuries
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to the anterior cruciate ligament, that infamous
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ACL tear. It's a really significant problem,
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actually, and quite complex when you look closely.
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The sources we've drawn on top, orthopedic resources
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like orthobullets, ortho info, stat pearls, the
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bone school, they give us a pretty detailed picture
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from the tiny fibers of the ligament itself right
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through to the... Well, often long road to recovery.
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Absolutely. So our aim here is to guide you,
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our listener, through what these resources tell
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us about ACL injuries. We'll look at what the
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ACL actually is, how these tears usually happen,
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how doctors work out what's gone wrong, the treatment
0:56
choices, what recovery involves, and, well, the
0:59
potential bumps in the road. It's a proper deep
1:02
dive into a major knee issue. Right. Let's get
1:05
started then. See what the sources lay out for
1:07
us. Okay, starting right at the beginning. When
1:09
we talk about the ACL, what exactly is it? Whereabouts
1:12
in the knee does it live and what's its job?
1:15
We know the knee is where those big leg bones
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meet, don't we? That's the place to start, yes.
1:21
The knee joint is essentially where three bones
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come together. You've got the femur, the thigh
1:25
bone coming down, the tibia, the shin bone below
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it, and then the patella. the kneecap sitting
1:30
at the front there. And holding these together,
1:32
giving stability, are strong bands called ligaments.
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Think of them like, well, really tough ropes.
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Ropes providing stability. OK. And the knee relies
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on several of these. It does. Four main ones.
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You've got the collateral ligaments running down
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the sides, the medial collateral, the MCL on
1:49
the inside, and the lateral collateral, the LCL
1:52
on the outside. They primarily stop the knee
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bending sideways, buckling inwards or outwards.
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Got it. Side to side stability from those. And
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then there are the ones inside the joint crossing
2:03
over. Precisely. Those are the cruciate ligaments.
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They form an X shape right in the center of the
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knee. There's the posterior cruciate ligament,
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the PCL, towards the back, and the anterior cruciate
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ligament, the ACL, at the front. And these two
2:15
are really crucial for controlling the forward
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and backward movement of the tibia relative to
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the femur. And our focus today, the ACL. Where
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is it within that X and what are its main functions
2:25
according to these sources? So the ACL runs diagonally
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right through the middle of that joint space.
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Its role is absolutely fundamental for knee stability.
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The sources really flag up two key jobs. First,
2:41
stopping the tibia from sliding too far forward
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relative to the femur. Alright, that forward
2:45
slide. And second, providing rotational stability.
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That's vital for any twisting, pivoting, changing
2:50
direction type movements. It's not huge, actually
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usually about 32 millimeters long, maybe 7 to
2:55
12 millimeters wide. So it's not just stopping
2:57
that shin bone shifting forwards, but also controlling
3:00
the twisting. That rotational part sounds critical
3:03
for anything dynamic. Oh, absolutely, it's crucial.
3:06
And the sources, they actually break the ACL
3:08
down further. They talk about its two main parts,
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or bundles, the andromedial bundle, the AM, and
3:14
the post -relateral bundle, the PL. two parts
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doing slightly different jobs. Tell me more about
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that. Yes, they have subtly different roles and
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they get tight at different points in the knees
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movement. The AM bundle is described as being
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more isometric, meaning its length doesn't change
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that much as the knee bends and straightens.
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It's tightest when the knee is bent in flexion.
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Okay. Its main job is resisting that straightforward
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movement of the tibia. It gives about 85 % of
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that anterior stability. The main stabilizer
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for forward movement? Largely, yes. The PL bundle,
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on the other hand, changes length more. It's
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tightest when the knee is straight in extension,
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and it's primarily responsible for controlling
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that rotational stability we mentioned. That's
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fascinating. So perhaps if someone has a partial
3:59
tear, which bundle is affected could influence
4:02
the specific type of instability they feel? That's
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exactly right. Although it's worth noting, the
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sources say most ACL injuries are complete or
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very near complete tears. But partial tears do
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happen. The ligament itself, it's mostly type
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I collagen that gives it its strength. It gets
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blood supply from the middle geniculate artery
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and has some nerve endings too. It's remarkably
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strong. Actually, it can withstand forces around
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2200 Newtons. That sounds like a lot. It is significant,
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yes. But clearly, under certain conditions, particularly
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in sports, the phosis can exceed that. Right,
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which brings us neatly to the next point. How
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does this strong ligament actually get torn?
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What are the typical scenarios that lead to an
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ACL injury? The sources are very consistent here.
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The most common mechanism by far is what's known
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as a non -contact pivoting injury. Non -contact,
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so it doesn't have to involve a collision or
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being tackled. Correct. In most cases, no one
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touches the person. It usually happens when the
5:00
food is firmly planted on the ground and the
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body twists or pivots forcefully over the slightly
5:04
bent knee. Often, the knee collapses inwards
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what we call a valgus position. Ah, I can picture
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that. The foot stays put, the body turns, and
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the knee caves in. Precisely. The tibia is essentially
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forced forwards relative to the femur, often
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with that twisting element, and the ACL just
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can't handle that load. That valgus collapse
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seems to be a recurring theme in sports injuries.
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It is indeed. Other common non -contact ways
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it can happen include stopping very suddenly
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when running, slowing down rapidly, or landing
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awkwardly from a jump. Direct contact, like a
5:39
tackle in rugby or football, can definitely cause
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an ACL tear too, often along with other ligament
5:44
damage, but it's less frequent than the non -contact
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type. And certain sports are just inherently
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riskier because they involve these movements
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constantly. Absolutely. Sports like football,
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basketball, skiing, netball, they're frequently
5:55
mentioned because they demand so many rapid changes
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of direction. Cutting maneuvers, jumping, landing,
6:00
sudden stops. The courses also suggest the rise
6:02
in ACL injuries might be partly linked to more
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people participating in high level high -intensity
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sports. OK, so that non -contact pivot is the
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primary culprit. Now let's think about who gets
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these injuries. Is it mainly professional athletes?
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Well, it's surprisingly common across the active
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population, not just pros. The sources quote
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figures like around 400 ,000 ACL reconstructions
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happening each year in the U .S. alone. They
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actually account for about half of all knee injuries
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treated surgically. The overall rate is about
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1 in 3 ,500 people per year in the U .S. Wow,
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that's a lot. It is. And while it can happen
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to anyone, any age, the sources consistently
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highlight a much higher incidence among female
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athletes. That's a really important point. Female
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athletes are often cited as being more susceptible.
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What sort of difference are we talking about
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and what reasons do the sources give? The ratio
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mentioned is quite stark. Roughly 4 .5 female
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athletes injure their ACL for every one male
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athlete playing similar sports, so a significantly
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higher risk. Four and a half times higher. That's
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huge. It is. And interestingly, the sources also
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mention female athletes tend to get these injuries
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younger, and often it's the supporting leg that
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goes, whereas males might more often injure their
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kicking leg. Okay, so why? What's behind this
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disparity? What factors contribute to female
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athletes being at greater risk? The sources suggest
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it's not one single thing, but rather a combination
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of factors. It's multifactorial. They point to
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differences in physical conditioning, overall
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muscle strength, and perhaps crucially, neuromuscular
7:34
control. Neuromuscular control? Can you unpack
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that a bit? What does that mean in this context?
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It's essentially how the brain coordinates muscle
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activity during movement, particularly during
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dynamic actions like landing from a jump or quickly
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changing direction. The sources suggest female
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athletes may be more prone to landing or cutting
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with increased valgus at the knee. That inward
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collapse we mentioned potentially combined with
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less bending at the hip and knee to absorb the
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shock. So the way they land and move puts more
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stress on the knee joint itself. Potentially,
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yes. They might also exhibit this valgus pattern
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more when fatigued, possibly due to differences
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in muscle fatigue resistance. Another key point
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raised is about muscle activation patterns. Some
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research suggests female athletes can be more
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quadriceps dominant. Meaning they rely more on
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the front thigh muscles? Exactly. They might
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engage their quads more heavily during deceleration
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or landing. The issue is, the hamstrings, the
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muscles at the back of the thigh, are actually
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more effective at preventing the tibia from sliding
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forward, which is what protects the ACL. Over
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reliance on the quads during these movements
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might place abnormal stress on the ligament.
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Weaker core stability compared to males is also
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sometimes mentioned, as it affects overall control.
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OK, so it's about how the muscles fire and control
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movement and how forces are absorbed. Are there
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physical or anatomical differences discussed
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too? Yes, anatomical factors are also suggested
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as potential contributors, though these are obviously
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less easy to modify. Things like ERM, possibly
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increased BMI, having a narrower space in the
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femur where the ACL sits the femoral notch. perhaps
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a smaller ACL ligament overall or greater general
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joint flexibility or laxity. And wasn't there
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mention of hormones as well? Yes, the sources
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do touch upon potential hormonal influences,
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but they are careful to state this is still a
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somewhat controversial area without definitive
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proof. The idea is that fluctuations in hormones
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like estrogen might affect the properties of
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ligaments. There's also a suggestion that coordination
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could be subtly affected during certain phases
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of the menstrual cycle, like the pre -ovulatory
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phase. Interestingly, one study noted athletes
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using oral contraceptives seemed less affected,
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but again, it's complex. So, a potential factor,
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but the jury's still out on the exact role of
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hormones. Anything else that increases risk?
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Genetics might play a part. Variations in genes
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related to collagen, like COO5A1, have been linked
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to injury risk. And other general risk factors
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include having had a previous concussion, which
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could affect balance and reaction times, and
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unsurprisingly, having had a previous ACL injury
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on either knee significantly raises your risk
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of having another one. That's a really thorough
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overview of the risk factors, showing just how
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complex this issue is, particularly for female
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athletes. Now, when the ACL does tear, it often
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doesn't happen in isolation, does it? Other structures
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in the knee frequently get damaged simultaneously.
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That's a critical point the sources emphasize.
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About half of all ACL tears involve damage to
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other parts of the knee as well. In acute injuries,
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meaning recent ones, damage to the lateral meniscus,
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the cartilage on the outside of the knee is very
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common. One source puts it at 54 % of cases.
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Over half. Yes. And injuries to the PCL, the
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LCL, or the structures in the back outer corner
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of the knee, the post -relateral corner, can
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also occur at the same time. And what happens
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if an ACL tear isn't addressed, if the knee remains
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unstable over the long term? The sources are
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quite clear on this. A knee that's chronically
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deficient in its ACL is highly prone to progressive
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damage. This often involves chondral injuries
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damaged to the smooth, articular cartilage that
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lines the joint surfaces and more complex meniscal
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tears developing over time. Things like those
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difficult -to -repair bucket -handle tears of
11:19
the medial meniscus become more common in chronically
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unstable knees. So living with that instability
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isn't just inconvenient, it actually increases
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the risk of more permanent joint damage down
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the line. Precisely. It significantly increases
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the risk of developing further problems, including
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the earlier onset of osteoarthritis. That really
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underlines why getting a proper diagnosis and
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appropriate management is so important. Okay,
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let's switch focus now to actually recognizing
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and diagnosing an ACL tear. What does it typically
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feel like for the person at the moment it happens?
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The sources paint a pretty consistent picture
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of the immediate experience. A very common report
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is hearing or feeling a sudden, distinct pop
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sound or sensation from within the knee right
12:00
at the moment of injury. The classic pop. I often
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hear about that. Yes, it's mentioned frequently.
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After the pop, patients often describe a feeling
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of the knee instantly giving way or buckling
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under them. Then comes the pain, usually felt
12:13
deep inside the joint. In the majority cases
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around 70%, according to one source, there's
12:18
significant and rapid swelling. Why does it swell
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up so quickly? That's due to bleeding inside
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the joint from the torn ligament fibers. It's
12:26
called hemarthrosis. It's a strong sign that
12:29
a significant injury has occurred within the
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joint capsule. Other common symptoms include
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difficulty putting weight on the leg, a more
12:35
general ache around the knee, that persistent
12:37
feeling of instability, especially when trying
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to cut or pivot loss of the full range of knee
12:42
movement, and tenderness if you press along the
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joint line. OK, so that combination. Pop. giving
12:48
way, pain, and fast swelling. Those are the big
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initial clues. But I've heard sometimes the initial
12:53
pain and swelling can actually subside after
12:56
a while. They can, yes, and this is a really
12:58
crucial point the sources make. The acute pain
13:01
and swelling might settle down after a few days
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or weeks, especially with rest. However, the
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underlying mechanical problem, the instability
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from the torn ligament, is still there. If the
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person then tries to return to sports or activities
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involving cutting and pivoting, the knee is very
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likely to feel unstable and give way again. And
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it's these repeated episodes of instability,
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this buckling, that puts the meniscus and the
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articular cartilage at such high risk of further
13:28
damage that progressive wear and tear we talked
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about. So even if it feels a bit better, the
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instability remains, potentially causing more
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harm over time if you try to push through it.
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Got it. How do doctors then confirm it is an
13:40
ACL tear and figure out the full picture of the
13:43
damage? The diagnostic process really starts
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with listening carefully to the patient's story.
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How exactly did the injury happen? What did they
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feel? Could they walk afterwards? That history
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is key. Then comes a physical examination, which
13:55
is absolutely vital. And comparing to the good
13:58
knee is important, always. Comparing the injured
14:01
knee to the uninjured one is essential to establish
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the person's baseline level of laxity, as everyone's
14:07
different. Doctors will look for swelling, check
14:11
for things like a quadriceps avoidance gait,
14:13
where the patient subconsciously avoids fully
14:15
straightening the knee and assess for any pre
14:18
-existing alignment issues. They'll also perform
14:21
specific tests for associated injuries like meniscal
14:24
tears or damage to other ligaments. A lack of
14:27
full knee extension is a particularly important
14:29
finding as it might signal a trapped piece of
14:31
meniscus or early stiffness setting in. And there
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are those specific hands -on tests for the ACL
14:36
itself, provocative tests. Which ones are the
14:39
mainstays? Yes. The Lackmann's test is widely
14:41
considered one of the most sensitive and reliable
14:43
tests, especially soon after the entry. How does
14:46
that one work? The examiner has the patient lying
14:48
down, knee bent slightly, usually around 30 degrees.
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They stabilize the thigh bone with one hand and
14:54
gently pull the shin bone forward with the other.
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In an ACL tear, you'll often feel the shin bone
14:58
move forward more than on the uninjured side.
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And crucially, you won't feel a distinct, firm
15:03
stop, what we call the endpoint. It feels sort
15:06
of mushy or empty. Looking for that excessive
15:09
forward slide and the lack of a solid stop. Exactly.
15:12
The sources give it high accuracy ratings, around
15:15
95 % sensitivity and 94 % specificity. The amount
15:19
of forward movement helps grade the tear, and
15:21
comparing sides is absolutely key. Makes sense.
15:24
What about the anterior drawer test? Is that
15:26
similar? It's another common one, yes. For this,
15:28
the knee is bent more to 90 degrees, usually
15:31
with the foot resting flat. The examiner sits
15:33
lightly on the foot and pulls the top of the
15:35
shin bone forward. Again, excessive forward movement
15:37
compared to the other side suggests an ACL tear.
15:40
Interestingly, the sources note this test is
15:43
often more reliable or easier to interpret in
15:46
chronic ACL tears, perhaps when the initial pain
15:48
and muscle spasm have subsided. Right, so Lachman's
15:52
may be better acutely, anterior drawer potentially
15:54
more obvious later on, and the pivot shift test.
15:57
That sounds like it's deliberately trying to
15:59
make the knee feel unstable. It is, in a controlled
16:02
way. It aims to replicate that giving way sensation
16:06
the patient might describe. The examiner takes
16:08
the knee from a straight position, applying a
16:11
bit of inward pressure, valgus, and internal
16:13
rotation to the lower leg and then bends the
16:16
knee. If the ACL is torn, the tibia might start
16:19
slightly forward when straight and then noticeably
16:21
clunk or shift back into place as the knee bends
16:23
to around 20 -30 degrees. So you're basically
16:26
inducing that little subluxation and reduction
16:28
to see if it happens. That's the idea. However,
16:31
it can be quite difficult to get a positive pivot
16:33
shift test in someone who's awake and apprehensive
16:36
or in pain, as muscle guarding can prevent the
16:38
shift. It's often much easier to demonstrate
16:42
under anesthesia when the muscles are fully relaxed.
16:45
Because of this, the sources say it's highly
16:47
specific if you get a positive test, it's almost
16:50
certainly an ACL tear, 98 % specificity, but
16:53
not very sensitive, maybe only 24 % in the clinic,
16:56
because it's often negative even when a tear
16:58
is present. That explains why it's not always
17:01
positive, even with a definite tear. Are there
17:03
any other, maybe simpler, tests mentioned? Yes,
17:06
the sources mention the lever sign test. The
17:08
examiner puts their fist under the patient's
17:10
upper calf and pushes down on the thigh. If the
17:13
ACL is intact, the heel should lift off the couch.
17:16
If it's torn, the heel tends to stay down. There
17:18
are also devices, like the KT1000 Arthrometer,
17:21
which can provide an objective measurement of
17:24
that anterior tibial translation, quantifying
17:26
the laxity. Okay, so a combination of the story,
17:29
the general exam, and these specific tests usually
17:31
gives a strong indication. What about imaging?
17:34
X -rays can't see ligaments directly, can they?
17:36
No, that's right. Standard X -rays mainly show
17:39
bone. They're important initially to rule out
17:41
any fractures associated with the injury or to
17:43
see signs like significant joint swelling. The
17:46
ACL itself won't show up. However, X -rays can
17:49
reveal subtle signs that are highly suggestive
17:52
of an ACL tear. such as what sort of clues might
17:55
you see on an x -ray? A classic sign is the second
17:58
fracture. It's a tiny chip of bone pulled off
18:00
the outer edge of the top of the tibia near where
18:03
another ligament the enterolateral ligament,
18:05
attaches. The sources state this finding is almost
18:08
pathognomonic, meaning it strongly indicates
18:10
an ECL tear, present in 75 % to 100 % of cases
18:14
where it's seen. Wow, so that little fleck of
18:16
bone is a massive clue. It really is. Other x
18:19
-ray findings might include a similar fracture
18:21
off the fibula head, an arcuate fracture, a depression
18:24
on the outer part of the femur's lower end, a
18:26
deep sulcus sign, obvious joint diffusion or
18:28
swelling, or particularly in children, and a
18:31
vulcan fracture where the ACL has pulled a piece
18:33
of the tibial spine bone off with it. So even
18:35
without seeing the ligament. X -rays provide
18:37
crucial, indirect evidence. But to actually visualize
18:40
the ACL and check for damage to meniscus or cartilage,
18:44
MRI is the key tool, isn't it? Correct. Magnetic
18:46
Resonance Imaging, MRI, is considered the primary
18:49
imaging modality. It's used to confirm the ACL
18:52
tear diagnosis and, very importantly, to evaluate
18:54
all the other structures within the knee, the
18:56
menisci, the articular cartilage, the other ligaments.
18:59
While a good clinical exam can often diagnose
19:01
an ACL tear reliably, the MRI gives that detailed
19:04
map of any associated damage, which is vital
19:07
for planning the right treatment. And how accurate
19:10
is MRI for spotting ACL tears? Very accurate.
19:12
The source is typically, quote, sensitivity between
19:15
86 % and 97 % and specificity correctly identifying
19:19
when it's not torn between 95 % and 100%. What
19:22
does a torn ACL actually look like on the scan?
19:24
Well, a normal ACL usually appears as a continuous
19:27
dark band on the MRI images, particularly the
19:30
sagittal views looking from the side. When it's
19:33
torn, you might see a clear break in those fibers,
19:35
or the ligament might look wavy, thickened, or
19:38
have increased signal within it, making it look
19:40
brighter on certain sequences. Sometimes it's
19:42
just not clearly visualized where it should be,
19:44
or its angle looks abnormal compared to bony
19:47
landmarks like Blumensatz line. On coronal views
19:50
from the front, you might see discontinuity or
19:53
just fluid signal in the space where the ACL
19:55
should be sometimes called the empty notch sign.
19:57
So looking for disruption, abnormal signal, or
20:00
just absence of the normal structure, are there
20:03
other signs on MRI like that bone bruising you
20:05
mentioned? Yes, bone bruising is a very common
20:07
secondary finding in acute tears seen in more
20:10
than half of cases. These show up as areas of
20:13
edema or fluid signal within the bone marrow,
20:15
typically in characteristic spots. The middle
20:18
part of the lateral femoral condyle and the back
20:20
part of the lateral tibial plateau. It's thought
20:23
these bruises reflect the impact forces during
20:25
the injury. And they might have longer term implications?
20:28
Possibly. The source has mentioned these bone
20:31
bruises can sometimes persist for years and might
20:33
contribute to the later development of osteoarthritis.
20:36
Other secondary MRI signs could include visible
20:39
damage to the MCL or objective measurement of
20:42
more than seven millimeters of anterior tibial
20:44
shift on the sagittal view. That bone bruising
20:47
idea potentially linking to later arthritis is
20:50
sobering. What about CT scans? Are they useful
20:53
for diagnosing ACL tears? Generally, no, not
20:56
for the initial diagnosis of the ACL tear itself.
20:59
CT is much better at looking at bone detail than
21:02
soft tissues like ligaments. However, the sources
21:05
highlight that CT scans become very valuable
21:07
in the revision setting. When a previous reconstruction
21:10
has failed. Exactly. If someone needs surgery
21:12
because a previous ACL graft hasn't worked, a
21:15
CT scan is the best test to accurately assess
21:17
the condition of the bone tunnels created during
21:19
the first surgery. It can show if the tunnels
21:22
have widened significantly or if there's bone
21:24
loss, which is critical information for planning
21:26
the revision operation. Okay, so MRI for the
21:28
initial soft tissue picture, x -rays for bony
21:31
clues, and CT, mainly for revision surgery planning.
21:36
Is looking inside with a camera arthroscopy ever
21:39
used just for diagnosis? Yes, knee arthroscopy
21:42
keyhole surgery allows the surgeon to directly
21:45
look at the ACL and confirm if it's torn. and
21:48
whether it's a partial or complete tear. This
21:50
is often done as the first step of the actual
21:52
reconstruction surgery anyway. And injecting
21:55
dye, orthography. Arthrography is mentioned as
21:57
being highly accurate, technically the gold standard
22:00
for sensitivity and specificity in some older
22:02
literature. But because it's invasive, involving
22:05
an injection into the joint, it's very rarely
22:07
used nowadays as a primary diagnostic tool when
22:10
MRI is so effective and non -invasive. Right,
22:12
so usually it's the clinical exam plus the MRI
22:15
that gives the definitive answer and maps out
22:17
the damage. Okay, let's move into section three,
22:18
the big decision point managing the injury, top
22:21
rate or not top rate. What guides this decision
22:23
according to the sources? The sources really
22:25
stress that it has to be an individualized approach.
22:29
There's no single right answer that fits everyone.
22:31
The best course of action depends heavily on
22:33
the specific patient, their age, how active they
22:36
are, what demands they place on their knee in
22:38
daily life or sports, whether there are other
22:40
injuries in the knee like a meniscus tear. All
22:42
these factors come into play. So surgery isn't
22:45
automatically required for every ACL tear. When
22:49
might a non -operative approach to be suitable?
22:51
Non -operative management, which focuses on physiotherapy
22:55
and potentially changing activities, is suggested
22:58
as an option for certain groups. This might include
23:01
older patients with low physical demands who
23:03
aren't involved in pivoting sports, or perhaps
23:05
recreational athletes who are happy to stick
23:07
to straight -line activities like cycling or
23:09
swimming. It might also be considered for some
23:12
partial ACL tears, especially in adolescents
23:15
where these are more common, if the knee feels
23:17
stable and tests like Lachman's are near normal.
23:20
And in young children with isolated tears, if
23:23
they're low demand and can reliably avoid risky
23:25
activities, a trial of non -operative treatment
23:28
might be used to delay surgery until they're
23:30
closer to skeletal maturity to protect their
23:32
growth plates. What does that non -operative
23:34
treatment typically involve? It usually starts
23:36
with managing the acute symptoms, the RICE -E
23:39
protocol. Rest, ice, compression, elevation,
23:42
settle, pain, and swelling. Then the core is
23:45
a dedicated physiotherapy program. often lasting
23:48
three months or more. This focuses on regaining
23:51
full knee range of motion, strengthening all
23:53
the muscles around the knee and hip, crots, hamstrings,
23:56
glutes, core muscles, and working on balance
23:58
and neuromuscular control. Regular follow -up
24:00
with a clinician is important to monitor progress
24:02
and stability. Interestingly, the sources mention
24:05
that functional knee braces don't seem to offer
24:07
any significant added stability for people managing
24:10
non -operatively. Right, the brace might feel
24:13
supportive but doesn't stop the underlying instability.
24:15
You mentioned trying to delay surgery in children.
24:19
What are the potential downsides or risks of
24:21
not having surgery, particularly for younger,
24:23
active people who want to get back to sport?
24:25
This is where the significant drawbacks of non
24:28
-operative management become clear, especially
24:30
if it's applied to the wrong patient group, like
24:32
active young people. The sources point to research,
24:36
like a study by Acroff, which followed children
24:38
with ACL tears treated without surgery. The outcomes
24:42
were concerning. They found high rates of ongoing
24:44
severe instability, poor knee function, and,
24:47
crucially, a very high incidence of secondary
24:50
damage occurring over time. What sort of secondary
24:52
damage did that study find? In that particular
24:55
study, out of 23 children treated non -operatively,
24:58
15 developed new meniscus tears, 3 suffered osteochondral
25:02
fractures involving cartilage and bone, and 10
25:05
showed early signs of osteoarthritis. This really
25:08
supports the understanding that those repeated
25:10
giving way episodes, the buckling due to instability,
25:14
place cumulative stress on the other structures
25:16
in the knee, leading to progressive damage. So
25:18
those instability episodes aren't just inconvenient,
25:21
they're actively harming the joint over time.
25:23
Exactly. The sources stress this risk of further
25:27
meniscus and cartilage injury is particularly
25:29
high if the person participates in what are called
25:32
Level 1 or 2 activities, basically anything involving
25:35
jumping, cutting, pivoting, side -to -side movements,
25:37
or heavy physical labor. So while delaying surgery
25:40
in very young children to protect growth is a
25:42
consideration, the sources imply that if the
25:45
child simply cannot avoid these activities or
25:47
the knee remains functionally unstable, the risk
25:49
of causing irreversible secondary joint damage
25:52
might actually outweigh the risks associated
25:54
with modern growth plate sparing surgical techniques.
25:57
That really highlights the challenging balance
25:59
in treating children and adolescents. So given
26:02
those risks associated with ongoing instability,
26:05
when is operative management typically ACL reconstruction?
26:08
the recommended path. ACL reconstruction, replacing
26:12
the torn ligament with a graft, is generally
26:14
indicated for complete ACL tears, particularly
26:17
in younger, more active individuals. The evidence
26:20
suggests reconstruction significantly lowers
26:23
the risk of developing those secondary meniscus
26:25
tears and cartilage damage down the line. For
26:28
an active child or adolescent with a complete
26:30
tear, realistically limiting their activity sufficiently
26:32
to avoid risk is often very difficult, making
26:35
surgery common recommendation. It's also recommended
26:38
for older patients even over 40 if they remain
26:40
highly active or have jobs with significant physical
26:43
demands. Age itself isn't necessarily a barrier
26:46
if the functional need is there. So it's more
26:48
about the needs required function than just the
26:50
patient's age. Precisely. Other indications include
26:53
partial tears that still cause significant clinical
26:56
instability and functional problems or cases
26:59
where non -operative treatment has been tried
27:01
but failed with instability persisting. If there's
27:05
an associated meniscus tear that needs surgical
27:08
repair, particularly if it's blocking knee movement,
27:11
the ACL is often reconstructed at the same time.
27:14
A really critical point mentioned repeatedly
27:16
is that unless a meniscus tear is blocking motion,
27:19
the patient must regain full range of motion
27:21
before surgery. Operating on a stiff knee dramatically
27:24
increases the risk of problematic post -operative
27:27
stiffness or arthrofibrosis. And naturally, if
27:30
a previous ACL reconstruction has failed, then
27:33
revision surgery is indicated. Okay, so reconstruction
27:36
is generally for active people needing a stable
27:38
knee for dynamic activities, aiming to restore
27:41
function and prevent further joint damage. The
27:43
source has also mentioned something important
27:45
about return to sport not just being about the
27:47
physical repair. Yes. That's a key insight. Success
27:51
after surgery isn't judged solely on the stability
27:53
of the knee. The sources highlight that successful
27:56
return to play is influenced by a whole mix of
27:59
factors. Physical recovery benchmarks, performance
28:02
on functional tests, demographic factors, and
28:05
significantly psychological readiness, things
28:07
like confidence in the knee and fear of re -injury.
28:10
It underscores that recovery is a holistic process.
28:13
Understood. Let's move into section four then
28:15
and get into the specifics of the surgery itself.
28:18
Generally speaking, how is an ACL reconstruction
28:21
carried out? The standard method nowadays is
28:23
arthroscopic assistant. It's keyhole surgery.
28:26
The surgeon makes a few small incisions around
28:28
the knee to insert a small camera, the arthroscope,
28:30
and specialized thin instruments. They prepare
28:33
the inside of the joint, clearing away the torn
28:35
remnants of the original ACL to get good views
28:37
of the bony landmarks. Although the sources do
28:40
note there's no clear evidence showing a difference
28:42
in outcome, whether you remove all the remnant
28:44
or leave a small stump behind, which some believe
28:46
might aid healing or proprioception. And you
28:48
mentioned earlier the ACL has those two bundles,
28:51
AM and PL. Do surgeons typically try to recreate
28:55
both? Anatomically, yes, it has two main bundles.
28:58
However, the most common surgical technique remains
29:00
single bundle reconstruction, where one graft
29:03
is positioned to replicate the function of both
29:05
bundles. While double bundle reconstruction using
29:08
two separate graphs might theoretically restore
29:10
the knee's natural mechanics more closely and
29:13
perhaps reduce laxity slightly more, the sources
29:16
state that currently studies haven't shown significant
29:19
differences in patient -reported outcomes between
29:21
the two techniques. So the single bundle approach
29:23
is standard and generally provides good results
29:26
for patients. Once the graft tissue is ready,
29:28
how is it actually positioned and secured inside
29:31
the knee? The graft needs to be passed through
29:33
bone tunnels drilled in the tibia and the femur,
29:36
spanning the joint and then firmly fixed to both
29:39
ends. There's a mention of preconditioning the
29:42
graft, applying some gentle tension to it before
29:44
final fixation, which might reduce some of the
29:47
initial stretching or creep that happens after
29:49
surgery. How much tension to apply during fixation
29:52
seems less critical. One high -level study cited
29:55
found no difference in outcomes between using
29:57
20 or 40 newtons of tension. The graft is usually
30:00
fixed with the knee held in about 20 to 30 degrees
30:03
of flexion. And how do they actually anchor it?
30:05
What are the fixation devices used? There are
30:07
quite a few options, and the choice often depends
30:09
on the type of graft being used. Fiji, bone plugs
30:13
versus soft tissue, and surgeon preference. Collin
30:17
methods include interference screws. These are
30:19
screwed into the tunnel alongside the graft,
30:22
wedging it tightly against the bone wall. Another
30:24
major category is suspensory fixation, like cortical
30:27
buttons, where the graft is essentially hung
30:29
from a small button resting on the outer surface
30:31
of the bone. Other devices like screw and washer
30:34
posts or staples are also used. Sometimes a combination
30:38
of methods is employed for extra security. Okay,
30:40
so screws, buttons, various ways to lock the
30:43
new ligament in place. The sources seem to really
30:45
emphasize that exactly where those bone tunnels
30:47
are drilled is incredibly important for success.
30:49
Why is tunnel placement so critical? It's paramount.
30:53
Tunnel placement dictates the position and angle
30:55
of the new graft within the joint. The goal is
30:58
to place the tunnels, and therefore the graft,
31:01
as close as possible to the location of the original
31:03
ACL. This is essential not just for restoring
31:06
the street forward anterior stability, but crucially
31:09
for restoring rotational stability as well. Getting
31:13
the tunnels drilled in a non -anatomical position
31:15
is cited as the single most common technical
31:17
error leading to graft failure. So precision
31:20
aiming is absolutely key. What are the guiding
31:22
principles for getting those tunnels in the right
31:24
spot? For the femoral tunnel in the thigh bone,
31:27
the surgeon needs to place it correctly both
31:29
side to side, coronally, and front to back. Placing
31:33
it too vertically fails to control rotation effectively.
31:37
Placing it too far forward can make the knee
31:38
feel tight and bending, but loose when straight.
31:42
Placing it too far back risks breaking through
31:44
the back wall of the bone. Different drilling
31:46
techniques exist transcivial versus using separate
31:49
portals, but the sources suggest no major outcome
31:52
differences as long as the final placement is
31:55
anatomical. Drilling this tunnel with a knee
31:57
significantly bent helps prevent that posterior
32:00
wall blowout. For the tibial tunnel in the shin
32:03
bone, its position relative to the remaining
32:05
PCL and other landmarks is crucial. If it's too
32:09
far forward, the graft can impinge on the roof
32:11
of the joint when the knee straightens. If it's
32:13
too far back, it might impinge on the PCL. The
32:16
angle it's drilled at is also important. It sounds
32:18
like navigating those tunnels requires extreme
32:20
precision. You also mentioned earlier that ACL
32:23
repair, fixing the original ligament, is seeing
32:25
some renewed interest. How does that differ from
32:28
reconstruction and when might it be considered?
32:31
Yes, repair involves attempting to reattach the
32:34
patient's own torn ACL rather than replacing
32:36
it entirely with a graft. Historically, ACL repairs
32:40
had very high failure rates, which led to reconstruction
32:43
becoming the standard. However, there's definitely
32:47
been a resurgence of interest recently, particularly
32:49
for very specific types of tears and potentially
32:52
in children. What kind of specific tears might
32:54
be suitable for repair, according to the sources?
32:57
The main indication mentioned is for ACL evulsion
32:59
injuries. This is where the ligament itself is
33:02
largely intact. but has been pulled off its bony
33:05
attachment, either on the femur or the tibia,
33:07
sometimes taking a piece of bone with it. It's
33:09
not generally considered for tears within the
33:12
main substance of the ligament itself. In adolescent
33:14
sneering skeletal maturity, certain repair techniques
33:17
using suture anchors or suspensory fixation might
33:20
offer a way to restore stability with potentially
33:22
less risk to the growth plate compared to drilling
33:24
large tunnels for a reconstruction graft. And
33:27
are the outcomes improving with these newer repair
33:29
methods? It's an evolving field. The sources
33:32
acknowledge the poor historical results, but
33:34
note that newer techniques, sometimes combined
33:37
with biological augmentation scaffolds like the
33:40
Bayer implant trial, are being investigated and
33:42
showing some promising early results in specific
33:45
patient groups, with comparable outcomes to reconstruction
33:48
reported at the two -year mark in some studies.
33:50
But it's not yet mainstream for most ACL tears.
33:54
Interesting. One to watch, perhaps. What about
33:56
the situation where a previous ACL reconstruction
33:59
has failed that requires a revision surgery you
34:02
mentioned? Yes, ACL revision reconstruction is
34:04
necessary when the initial graft fails and the
34:07
patient is experiencing unacceptable instability
34:09
during their desired activities. It's typically
34:12
a more complex operation than the first time
34:14
surgery. What makes revision surgery more challenging?
34:16
Several things. Firstly, the surgeon needs to
34:19
figure out why the first one failed. Was it a
34:21
technical error like tunnel malposition? Was
34:24
a graft choice inappropriate? Did the fixation
34:26
fail? Was there an undiagnosed associated injury
34:30
putting extra stress on the graft? or did the
34:32
patient re -injure it? Secondly, the bone tunnels
34:35
from the first surgery are often enlarged or
34:37
may be positioned non -anatomically, which complicates
34:40
drilling new tunnels correctly. Thirdly, graft
34:43
choice becomes more critical. The sources generally
34:46
recommend using high -strength grafts for revisions.
34:48
Often autografts like quadriceps tendon or hamstring
34:51
is available, or sometimes allograft, donor tissue.
34:54
Re -harvesting a BPTV graft from the same knees
34:57
usually advised against because the bone quality
34:59
might be compromised, surgeons often use enhanced
35:02
fixation methods, perhaps dual fixation points.
35:05
If the old tunnels are very large, say over 50
35:07
millimeter, or interfere with replacing new tunnels
35:10
anatomically, the revision might need to be staged
35:12
first surgery to bone graft the old tunnels,
35:14
then a second surgery months later to do the
35:16
reconstruction. There's also some debate about
35:18
adding procedures, like a lateral extra -articular
35:21
tenodesis, LET. In revision cases, particularly
35:24
in young, high -risk patients, to provide extra
35:27
rotational control, though its routine use is
35:29
still controversial. Rehab after revision is
35:32
often more cautious, too. So revision is definitely
35:34
a step up in complexity, requiring careful investigation
35:37
and planning. Let's revisit graft selection for
35:40
primary reconstructions. You outlined a few options,
35:43
BPTB, hamstring, quad tendon, allograft. Can
35:47
you summarize the key pros and cons the sources
35:50
highlight for each? Certainly. This is a really
35:52
important discussion because the graft choice
35:54
impacts things like recovery, potential complications
35:57
like pain, and maybe even long -term outcomes
36:00
or re -repture risk. Autographs using the patient's
36:02
own tissue have the biological advantage of faster
36:05
incorporation, no immune reaction, and no disease
36:08
transmission risk. The downside is you have to
36:10
harvest it from somewhere, creating morbidity
36:13
at the donor site. Let's start with the bone
36:15
patellar tendon bone, BPTV, often called the
36:18
gold standard. It's frequently referred to that
36:20
way, yes, partly due to its long track record
36:22
of successful use, especially in high level athletes.
36:25
The main pro is that it provides bone plugs at
36:28
each end, allowing for bone to bone healing within
36:30
the tunnels, which is thought to be faster and
36:32
potentially more rigid early on. It's also a
36:35
very strong graft. The major con cited consistently
36:38
is a higher incidence of anterior knee pain at
36:41
the front of the knee, particularly when kneeling.
36:44
This is reported in 10 -30 % of patients. Rare
36:47
complications include patella fracture or patellar
36:50
tendon rupture. There's also a note about potentially
36:52
higher re -rupture risk if used in very young
36:55
patients under 20, or if the graft harvested
36:58
is less than eight millimeters wide. So strong
37:00
and reliable fixation, but potential for harvest
37:02
site pain. What about the hamstring autograph?
37:05
That seems incredibly common now. It is, yes.
37:07
Typically two tendons, semitendinosus and gracilis,
37:11
are harvested and folded over to create a four
37:13
-strand The main advantages are usually a smaller
37:16
incision, less pain immediately after surgery,
37:20
and significantly less anterior knee pain compared
37:22
to BPTB. It's also mechanically very strong,
37:25
often stronger than BPTB in lab testing. Potential
37:28
downsides include a theoretical concern about
37:30
residual hamstring weakness, especially peak
37:32
flexion strength, although the functional impact
37:35
is debated. Some sources raise a question about
37:37
whether this weakness, particularly in females,
37:39
could slightly increase rupture risk, but again,
37:41
that's not definitively proven. Is that hamstring
37:43
weakness usually noticeable long term? It can
37:46
be measurable, but whether it affects function
37:49
significantly varies. Other potential complications
37:52
include nerve irritation near the harvacite,
37:54
causing numbness, peristhesia, though certain
37:57
incision techniques might reduce this risk. Also,
38:01
because hamstring grafts are typically fixed
38:03
with suspensory devices like buttons, there's
38:05
the potential for a windshield wiper or bungee
38:08
cord effect, where the graft moves slightly within
38:10
the tunnels, which might lead to some tunnel
38:12
widening over time, though the clinical relevance
38:15
of this is also debated. That windshield wiper
38:17
image is quite descriptive. How about the quadriceps
38:20
tendon autograft? Is that becoming more popular?
38:22
It seems to be gaining traction, yes. It can
38:25
be harvested just as soft tissue or with a bone
38:28
block from the top of the patella. Key advantages
38:30
include the harvest incision being away from
38:32
the area you kneel on, which is beneficial for
38:34
some patients. If harvested without the bone
38:37
block, it avoids crossing the growth plate in
38:39
the tibia, making it a potentially good option
38:42
for skeletally immature patients compared to
38:44
BPTB. Its strength is good, comparable to the
38:47
native ACL, and patient outcomes seem similar
38:50
to other autografts. It's also often available
38:52
as a virgin graft option for revision surgeries.
38:55
Disadvantages are similar to hamstring grafts
38:58
if soft tissue fixation is used regarding potential
39:00
tunnel effects. So, perhaps a useful alternative
39:03
in certain situations. Lastly, allograft using
39:06
tissue from a donor. Pros and cons. The main
39:08
advantage of allograft is avoiding harvacite
39:10
morbidity altogether. This is particularly useful
39:13
in revision surgeries where good autograft options
39:15
might be limited or in complex cases involving
39:18
multiple ligament injuries. However, there are
39:21
significant downsides. Allografts are more expensive.
39:24
Biologically, they take longer to incorporate
39:26
into the patient's bone tunnels compared to autografts.
39:29
There's a very small but real risk of disease
39:32
transmission, although rigorous screening makes
39:34
this extremely rare. HIV risk is cited as less
39:38
than 1 in 1 .6 million. But the biggest concern
39:41
highlighted in the sources, especially for young
39:43
active patients, is a markedly increased risk
39:46
of graft failure or re -rupture. How much higher
39:49
is that rupture risk with allograft in young
39:51
people? The data cited is striking. For athletes
39:54
aged between 10 and 19 undergoing primary ACL
39:56
reconstruction, the odds of graft rupture were
39:59
reported to be over four times higher with allograft
40:02
compared to using their own tissue, autograft.
40:05
That's a massive difference and a major factor
40:07
influencing graft choice in that population.
40:09
A very powerful statistic indeed. Does the way
40:12
the allograft tissue is processed make a difference
40:15
to its quality or risk? Yes. Processing methods
40:18
matter. Fresh frozen allografts generally show
40:21
lower rupture rates compared to those treated
40:23
with chemicals or radiation. Irradiation, used
40:26
for sterilization, unfortunately weakens the
40:28
graft's mechanical properties. Higher doses significantly
40:31
reduce strength, and even lower doses decrease
40:34
stiffness. Other methods like defreezing or certain
40:38
chemical treatments might damage cells but not
40:41
significantly affect immediate strength. So fresh
40:43
frozen seems the preferred allograft type when
40:46
it's used. Let's loop back to the pediatric considerations.
40:50
We touched on the risk to open growth plates,
40:52
freezes. How do surgeons navigate this when operating
40:55
on children who are still growing? It's a major
40:57
challenge, absolutely. Injuring those active
41:00
growth plates during surgery, especially by drilling
41:02
large tunnels across them or using fixation methods
41:05
that compress them can potentially lead to problems
41:08
like premature growth arrest, angular deformities
41:10
of the leg, or differences in leg length later
41:12
on. How do they judge when a child is safe for
41:15
more adult -type surgery techniques? Skeletal
41:18
maturity is key. The sources suggest onset of
41:21
menstruation is often a good guide for girls
41:23
nearing maturity. Generally, males age 16 or
41:26
older and females 14 or older are often considered
41:29
to have mature enough growth plates to tolerate
41:31
adult -type reconstruction techniques. For younger
41:34
children with significantly open fices, surgeons
41:37
employ specific techniques designed to either
41:39
completely avoid drilling across the fizzes,
41:41
fizzle sparing, or to minimize the risk of damaging
41:44
it, fizzle respecting. There are various approaches
41:49
described. Some techniques keep the tunnels entirely
41:52
within the ends of the bones, the epithesis,
41:55
avoiding the fissus altogether. Others might
41:57
cross one fissus but try to do so minimally,
42:00
often centrally and vertically, partial transfusceal.
42:04
And there are full transfusceal techniques, similar
42:06
to adult surgery but using smaller tunnels drilled
42:09
very carefully to minimize the area of fissus
42:11
affected. Interestingly, the sources suggest
42:14
there aren't huge differences reported in growth
42:16
disturbance rates between these different specialized
42:19
pediatric techniques, implying that meticulous
42:22
surgical execution might be the most critical
42:24
factor. So they all carry some inherent risk,
42:26
but the techniques aim to be as safe as possible.
42:29
Are there techniques that involve structures
42:31
outside the joint as well? Yes, for very young
42:34
children. EG males under 12, females under 11.
42:37
Sometimes combined intraarticular and extraarticular
42:40
techniques are used. One example described uses
42:43
a strip of the iliotildial band, ITB, from the
42:46
outside of the thigh. It's harvested and routed
42:48
in a way that provides stability inside the joint
42:51
but avoids drilling across the main distal femoral
42:54
fissus, offering stability while minimizing growth
42:57
risk. And what about graft choice specifically
42:59
in children? The sources strongly indicate that
43:02
if a transfissal technique is used, crossing
43:04
the growth plate using a soft tissue graft like
43:07
hamstring, carry a significantly lower risk of
43:10
causing growth problems compared to using a graft
43:12
with bone blocks like BPTV that pass through
43:14
the physis. What are the biggest surgical mistakes
43:17
or factors that increase the risk of damaging
43:19
a growth plate in kids? The single most important
43:22
factor highlighted is the diameter of the tunnels
43:24
drilled across the physis. Larger tunnels obviously
43:27
damage a larger percentage of the growth plate
43:29
area. An 8mm tunnel might violate less than 3%,
43:33
while a 12mm tunnel could affect 7 -9 % or more.
43:37
Other risk factors include drilling tunnels at
43:39
very oblique angles across the physis, using
43:42
fixation devices like interference screws directly
43:44
across the physis, using high -speed burrs instead
43:47
of drills, adding certain extra -articular procedures,
43:50
dissecting too close to sensitive growth cartilage
43:53
around the joint edges, or placing sutures near
43:56
the tibial tubercle growth area. Despite all
43:59
care, the sources do note that some minor physical
44:01
disruption, visible on imaging but not causing
44:04
clinical growth problems, is reported in around
44:06
10 % of pediatric ACL cases. It really does underscore
44:09
the immense care and precision needed when operating
44:12
on a growing knee. Balancing stability with protecting
44:15
future growth is clearly a huge consideration.
44:18
It demands significant expertise and very careful
44:20
judgment, yes. Okay, we've thoroughly covered
44:22
the injury, how it's diagnosed, the decisions
44:25
around surgery. the different techniques including
44:27
for children, and graft choices. Let's move now
44:31
to what happens after surgery. Section five,
44:34
focusing on recovery, rehabilitation, and potential
44:38
setbacks. What's the main goal right after the
44:40
operation? The overall aim of the post -op care
44:43
and the entire rehab process is to safely restore
44:47
the knee's normal function, stability, and movement
44:49
patterns, ultimately allowing the patient to
44:52
return to their desired activities, including
44:54
sports, at a high level. Immediately after surgery
44:57
the focus is on managing pain and swelling. Aggressive
45:00
cryotherapy using ice or specialized cold compression
45:03
devices is really emphasized. Why the big push
45:06
on ice? The sources note it significantly helps
45:08
reduce pain and consequently the need for strong
45:11
pain medication. Early weight -bearing as tolerated
45:14
is also generally encouraged these days. It's
45:15
been linked to less pain at the front of the
45:17
knee later on. And getting that knee moving straight
45:19
away is important. Absolutely critical, especially
45:22
regaining full passive extension, getting the
45:24
knee completely straight passively. This should
45:27
be a priority from day one. It's particularly
45:29
vital if there were associated injuries like
45:31
an MCL sprain or patella dislocation treated
45:34
at the same time. Interestingly, the sources
45:36
also mentioned that research hasn't really shown
45:38
any major long -term differences between following
45:41
very aggressive accelerated rehab protocols versus
45:44
more traditional slower progressions. So the
45:47
exact speed might matter less than hitting the
45:49
key milestones. What kind of exercises are typically
45:52
done in the early stages of rehab? What's considered
45:54
safe and what should definitely be avoided? Early
45:57
rehab focuses on activating muscles and restoring
45:59
motion without putting undue stress on the healing
46:02
graft. Safe bets usually include things like
46:05
eccentric quadriceps. Strengthening sources suggest
46:08
this can start quite early, around three weeks,
46:11
and helps build muscle size and strength. Isometric
46:14
contractions. Just tensing the muscles without
46:16
moving the joint are safe for both hamstrings
46:19
and quives at any angle. Gentle active range
46:22
of motion, usually within a protected range like
46:24
35 to 90 degrees of flexion initially, is encouraged.
46:28
Core strengthening and exercises for the hip
46:30
muscles, particularly the glutes, are also fundamental
46:33
from the start. But the big emphasis in early
46:35
rehab, according to the sources, is on closed
46:37
chain exercises. Closed chain. What exactly are
46:41
those and why are they preferred early on? Closed
46:43
chain means exercises where the foot is fixed
46:45
or planted on a surface, like mini squats, leg
46:48
presses, or step ups. These exercises tend to
46:50
generate compressive forces across the knee joint
46:52
and are thought to put less direct shear stress
46:55
on the ACL graph compared to open chain exercises.
46:58
The sources specifically advise avoiding open
47:00
chain quadriceps strengthening in the initial
47:02
phases of rehab. Open chain being exercises like
47:05
the seated leg extension machine, where your
47:08
foot moves freely in space. Precisely. That kind
47:11
of exercise, especially straightening the knee
47:12
against resistance in the last 30 degrees or
47:14
so, effectively mimics the forces applied during
47:17
the anterior drawer and lachman tests. It creates
47:20
a significant anterior pull on the tibia, directly
47:23
stressing the new graft exactly what you want
47:25
to avoid while it's healing and incorporating.
47:28
That makes perfect sense. Don't repeatedly do
47:30
the movement that challenges the ligament you
47:32
just fixed. Do the rules about open -chain exercises
47:35
change later in rehab? This is where things get
47:38
a bit more nuanced. As rehab progresses, the
47:41
sources mention some updated evidence. Neuromuscular
47:44
electrical stimulation, NMES, applied to the
47:47
quads is highlighted as potentially beneficial,
47:50
showing improvements in strength when added to
47:52
standard rehab in the first few months. Regarding
47:55
open kinetic chain, OKC, exercises like leg extensions,
47:59
some more recent research cited suggests that
48:01
when introduced appropriately later in rehab,
48:04
for example, after four weeks, perhaps initially
48:06
in a limited range like 45 -90 degrees, there
48:09
might not be a significant detrimental effect
48:11
on knee laxity, strength, or patient -reported
48:14
function compared to solely sticking with closed
48:16
chain exercises. This seems to hold true regardless
48:19
of graft type. That's interesting. So maybe not
48:22
completely forbidden later on if done carefully.
48:24
What about where rehab takes place? Is going
48:26
to a physio clinic inherently better than a structured
48:28
home program? The sources suggest maybe not.
48:32
Studies comparing structured supervised physiotherapy
48:34
in a clinic versus equally structured home -based
48:37
rehab programs haven't consistently shown one
48:40
setting to be superior in terms of long -term
48:42
outcomes for strength, knee laxity, or function.
48:45
This implies that the quality and consistency
48:48
of the program and the patient's adherence to
48:50
it might be more important than the physical
48:52
location where it's performed. That's useful
48:54
information for patients potentially offering
48:56
more flexibility. Does doing rehab before the
48:59
surgery, prehab, make a difference? Yes. Preoperative
49:03
rehabilitation, typically involving a few weeks
49:05
of targeted exercises to improve muscle strength,
49:07
activation, and neuromuscular control before
49:09
the operation, is shown to have benefits. The
49:12
sources state it can improve patient reported
49:15
function and physical function scores in the
49:17
first three months after surgery. However, it
49:19
doesn't seem to significantly impact the ultimate
49:22
time to return to sport, or the overall success
49:24
rate of returning. So, it helps smooth out the
49:27
early post -op phase, but doesn't necessarily
49:29
speed up the final return. That brings us to
49:32
the million dollar question for many, especially
49:34
athletes. When can they actually get back to
49:37
playing their sport? This is still a complex
49:40
area, and the sources indicate there aren't universally
49:43
agreed upon definitive criteria for timing the
49:45
return to play. RTP. Historically, a common guideline
49:50
was no sooner than nine months post -op. However,
49:53
the focus is increasingly shifting towards meeting
49:55
objective performance -based criteria rather
49:58
than just relying on time alone. Meaning the
50:01
athlete has to pass certain tests. Exactly. Clearance
50:04
is often based on passing a battery of functional
50:06
tests designed to assess strength, power, balance,
50:09
and control during movements that simulate the
50:11
demands of their sport. Things like single leg
50:13
hop tests for distance and height, agility drills,
50:16
and assessment of landing mechanics. And how
50:17
they land is particularly important. Very important.
50:20
The sources specifically highlight that returning
50:23
to sport while still demonstrating poor movement
50:26
patterns, like that dynamic valgus knee collapse
50:29
during landing or cutting, significantly increases
50:32
the risk of re -rupturing the graft or tearing
50:34
the ACL in the other, previously uninjured knee.
50:38
Consistently, higher rates of reinjury and graft
50:40
failure are reported when athletes return prematurely
50:42
before meeting appropriate functional and strength
50:45
criteria. So impatience is a major risk factor
50:47
for ending up back at square one. Who makes the
50:49
final call on clearance? The decision should
50:51
ideally be a collaborative one, the sources suggest,
50:55
involving the surgeon, the physiotherapist, and
50:57
the patient. It needs to consider not just the
51:00
physical readiness demonstrated in testing, but
51:02
also psychological factors. Fear of re -injury
51:05
or lack of confidence can be significant barriers,
51:08
even if the knee is physically strong. While
51:10
the average RTP time frame is often quoted as
51:13
6 to 12 months, a crucial point raised is that
51:16
the biological process of graft healing, remodeling,
51:19
and maturing into a strong ligament can take
51:22
much longer, potentially 18 months or more. Returning
51:25
before the graft is fully mature and the neuromuscular
51:27
control is restored significantly increases the
51:30
risk. That need for patients allowing the biology
51:32
to catch up seems absolutely paramount. Now despite
51:36
best efforts complications can still occur after
51:38
ACL surgery. What are the main potential setbacks
51:41
or problems mentioned in the sources? The single
51:44
most common complication reported after ACL reconstruction
51:47
is loss of knee motion. leading to stiffness
51:50
or arthrofibrosis. The sources strongly correlate
51:53
this risk with not having achieved full range
51:55
of motion before the surgery. It typically presents
51:58
as difficulty fully straightening or bending
52:00
the knee and sometimes reduced mobility of the
52:03
kneecap. How do they try and prevent stiffness
52:05
and what's done if it does develop? Prevention
52:08
hinges on that preoperative range of motion,
52:11
waiting for the initial inflammation to settle
52:13
before operating, and diligent post -op physiotherapy
52:17
emphasizing early motion. particularly extension.
52:21
Aggressive icing also helps manage swelling which
52:23
can contribute to stiffness. If stiffness does
52:25
become a problem, the initial approach is intensive
52:27
physiotherapy, sometimes involving specific stretching
52:30
techniques or serial splinting to gradually regain
52:33
motion, especially within the first three months.
52:36
If significant stiffness persists beyond that,
52:38
a surgical procedure might be needed usually
52:40
in arthroscopic lysis of adhesions where the
52:43
scar tissue is released, often combined with
52:45
a manipulation under anesthesia to physically
52:47
push the knee through its range. Stiffness sounds
52:50
like a frustrating complication. What about problems
52:53
with the graft itself? What's the most common
52:55
reason for the actual reconstruction to fail?
52:58
Tunnel mount position. The sources are very clear
53:01
that drilling the bone tunnels in a non -anatomical
53:03
location is the leading cause of technical failure
53:07
of the graft, accounting for potentially up to
53:09
70 % of failures where the surgery itself is
53:11
the issue. The overall graft failure rate requiring
53:15
revision surgery is estimated around 5 -10 %
53:18
depending on the population. And what are the
53:20
consequences of those tunnels being in the wrong
53:22
place? It depends on the error. For example,
53:25
if the femoral tunnel is too vertical, a common
53:27
historical issue with older techniques, the graft
53:30
might stop forward sliding but fail to control
53:32
rotation, leading to persistent instability during
53:36
pivoting a positive pivot shift test. If the
53:39
tibial tunnel is too far forward, the graft can
53:41
get pinched or impinged by the roof of the intercondylar
53:43
notch when the knee straightens, causing pain,
53:46
swelling, and potentially limiting extension
53:49
or damaging the graft over time. Even small errors
53:52
in placement can compromise the graft's function.
53:55
So that surgical precision we discussed is truly
53:57
fundamental to avoiding the most common failure
54:00
mechanism. Are there other reasons a graft might
54:03
fail besides being put in the wrong spot? Yes,
54:06
several other causes are mentioned. Fixation
54:08
failure, the screws, buttons, or other devices
54:10
might loosen, break, or not hold the graft securely
54:13
enough. Graft tunnel mismatch can occur, for
54:15
example, if a BPTB graft's bone plugs are too
54:18
long for the tunnels drilled. A traditional failure
54:21
might happen if the graft tissue itself was too
54:23
thin or weak to begin with, EHEA hamstring graft
54:26
under 8mm diameter. In BPTV grafts, the bone
54:30
plug itself could technically dislodge within
54:31
the joint. A major cause is failure to diagnose
54:35
and treat associated injuries at the time of
54:36
the initial surgery. If significant damage to
54:39
the PCL or post -verlateral corner is missed,
54:42
the ACL graft will be overloaded and likely fail
54:45
over time. Improper or overly aggressive rehabilitation,
54:48
particularly those open -chain exercises too
54:50
early, can also contribute. And certain patient
54:52
factors are associated with higher failure risk,
54:54
like being very young, having significant pre
54:56
-existing knee hyperextension, returning to high
54:59
-risk sports very quickly, or having anatomical
55:01
factors like a steep posterior tibial slope.
55:03
It's clearly a complex interplay of surgical
55:05
technique, biology, rehabilitation, and patient
55:08
factors. What about infection after the surgery?
55:11
Is that common? Thankfully, joint infection,
55:15
or septic arthritis, is a serious but relatively
55:17
rare complication, occurring in less than 1 %
55:20
of primary ACL reconstructions according to the
55:23
sources. It's usually caused by common skin bacteria
55:25
like staph epidermidis or staph aureus. It typically
55:29
shows up within the first few weeks post -op
55:31
with increasing pain, swelling, warmth, redness,
55:35
and potentially systemic signs like fever. How
55:38
is an infection treated? Does it mean the graft
55:40
is lost? Diagnosis involves taking a fluid sample
55:43
from the knee joint. Treatment needs to be prompt
55:46
and aggressive. Usually a media arthroscopic
55:49
surgery to thoroughly wash out the joint, combined
55:51
with intravenous antibiotics for an extended
55:53
period, typically at least six weeks. The sources
55:57
suggest that with this approach, especially if
55:59
caught early and depending on the bacteria involved,
56:01
the graft can sometimes be successfully retained.
56:03
It doesn't automatically mean the reconstruction
56:05
has failed, but it requires significant intervention.
56:08
So treatable but requires swift action. Are there
56:12
any other specific complications worth mentioning
56:14
that appear in the sources? Yes, a few others
56:17
are listed. Infrapatellar contracture syndrome
56:20
is a specific rare type of stiffness involving
56:22
scar tissue forming below the kneecap. Patellar
56:25
tendon rupture or patella fracture can occur
56:28
usually months after surgery if a BPTB or quad
56:31
tendon graft with a bone block was used. Complex
56:34
regional pain syndrome, CRPS, previously known
56:37
as RSD, is another potential but uncommon pain
56:40
complication. Tunnel osteolysis gradual widening
56:44
of the bone tunnel seen on x -ray can occur over
56:47
time, but usually only needs monitoring unless
56:49
it causes graft loosening. Long -term, the risk
56:53
of developing late osteoarthritis is real, particularly
56:56
if there was significant meniscus or cartilage
56:57
damage initially, or in patients who are older
57:00
at the time of surgery. Nerve irritation, specifically
57:03
branches of the saphenous nerve near the hamstring
57:05
harvest site, can cause numbness or tingling
57:08
on the shin. And finally, a cyclops lesion is
57:11
a nodule of scar tissue that can form in the
57:13
front of the knee after surgery and physically
57:16
block the last few degrees of extension, sometimes
57:18
causing a noticeable click or clunk. That's quite
57:21
a comprehensive list of potential bumps in the
57:23
road, reinforcing that recovery isn't always
57:25
smooth sailing. Indeed. While the overall success
57:28
rate is high, surgeons and patients need to be
57:31
aware of these potential issues. Okay, let's
57:33
move to our final section, section six. Looking
57:35
at the long -term outlook and injury prevention,
57:38
we've already discussed the risks of not treating
57:40
an ACL tear the progressive damage. What's the
57:44
general prognosis with treatment, with reconstruction,
57:47
according to the sources? The sources generally
57:49
portray the natural history of an untreated ACL
57:52
deficient knee as one leading towards accelerated
57:55
arthritis and further joint damage due to the
57:57
chronic instability. However, with a successful
58:00
surgical reconstruction followed by thorough
58:02
and appropriate rehabilitation, the prognosis
58:05
is typically described as good. The aim is to
58:08
restore knee stability and function very close
58:10
to its pre -injury state, enabling a high level
58:12
of return to activity and sport for most patients.
58:15
That's certainly positive news for those facing
58:18
this injury and the subsequent recovery journey.
58:20
Now, considering everything we've discussed,
58:23
the specific ways these injuries happen, the
58:25
risk factors like biomechanics and neuromuscular
58:27
control, especially in female athletes, the challenges
58:30
of recovery, including re -injury risk, do the
58:33
sources talk much about preventing ACL tears
58:35
from happening in the first place? Yes, absolutely.
58:38
Injury prevention is a significant focus in the
58:40
literature reviewed, particularly prevention
58:42
programs aimed at athletes, and with a specific
58:45
emphasis on female athletes due to that higher
58:48
risk profile we discussed. The cornerstone of
58:51
these prevention strategies is neuromuscular
58:53
training and plyometrics. Neuromuscular training
58:55
and plyometrics. So exercises focusing on jumping,
58:59
landing, and coordination. What's the underlying
59:01
principle? Exactly. It involves specific exercises
59:04
designed to improve the communication and coordination
59:06
between the brain and the muscles that control
59:08
the knee and hip. The goal is to retrain movement
59:11
patterns, teaching athletes, for example, to
59:13
land softer, with more bend at the knees and
59:16
hips to absorb shock, and crucially, to avoid
59:18
letting the knee collapse inwards into that risky,
59:21
valgus position. It also often includes strengthening
59:24
exercises, particularly for the hamstrings and
59:27
glutes, to improve the muscle balance around
59:29
the knee and reduce quadriceps dominance. So
59:32
it's really about actively training safer ways
59:35
to move to make the knee more resilient during
59:38
those high -risk maneuvers. Are there other prevention
59:40
tips mentioned? For skiers specifically, the
59:43
sources mentioned that teaching proper falling
59:45
techniques can help reduce injury risk. Regarding
59:48
knee braces for prevention, the general consensus
59:50
from the sources is that there's no convincing
59:52
evidence that wearing a brace prevents an initial
59:54
ACL injury in healthy athletes. The only potential
59:58
exception mentioned is for skiers who already
1:00:00
have an ACL deficiency, where a brace might provide
1:00:03
some benefit. So proactive training focused on
1:00:05
movement quality seems far more effective than
1:00:08
relying on external equipment for prevention.
1:00:10
That's certainly the message that comes through
1:00:12
from the evidence presented in these sources.
1:00:14
Well, this has been an incredibly detailed exploration
1:00:17
of ACL injuries. We've gone from the basic anatomy,
1:00:20
the different bundles within the ligament right
1:00:22
through to the complex biomechanics of how tears
1:00:25
happen, the diagnostic process, the critical
1:00:28
decisions around surgery versus non -surgical
1:00:30
management, the intricacies of different reconstructions,
1:00:33
techniques and graphs, the long and demanding
1:00:35
path of rehab, potential complications, and finally
1:00:39
the prospects for prevention. We've really unpacked
1:00:42
what these orthopedic resources reveal about
1:00:44
this very common yet very significant knee injury.
1:00:47
I think the key takeaways are understanding those
1:00:50
non -contact mechanisms, recognizing the risk
1:00:53
factors, particularly around neuromuscular control
1:00:56
and landing mechanics, appreciating why precise
1:00:59
surgical technique is so vital if reconstruction
1:01:02
is undertaken, and acknowledging that comprehensive
1:01:06
evidence -based rehabilitation, including addressing
1:01:09
psychological factors, is absolutely essential
1:01:12
for a successful outcome. It certainly paints
1:01:14
a clear picture of the journey someone faces
1:01:16
after hearing that pop all the way through to
1:01:19
hopefully getting back to full activity. It highlights
1:01:21
the biological, mechanical, and psychological
1:01:24
challenges involved, definitely. And if you,
1:01:27
our listener, have found this deep dive informative
1:01:30
and valuable, we'd be very grateful if you could
1:01:32
take a moment to rate and share the show. It
1:01:34
really helps more people discover these insights.
1:01:36
And perhaps as a final thought to leave you with,
1:01:39
considering everything we've discussed today,
1:01:41
The strong links between how we move, our muscle
1:01:44
control, even our mental readiness, and both
1:01:46
the risk of getting an ACL injury and the success
1:01:49
of recovering from one, plus the ongoing challenge
1:01:53
of re -injury. How much potential lies beyond
1:01:56
just surgical repair? How might a much greater
1:01:59
society -wide emphasis on mastering movement,
1:02:02
implementing proactive injury prevention focused
1:02:04
on biomechanics from a young age, and fully integrating
1:02:07
psychological preparation into athletic development
1:02:10
truly change the landscape for athlete health
1:02:12
and longevity in the future? That's a powerful
1:02:15
question to ponder. Thank you for joining us
1:02:17
on the Deep Dive for this comprehensive look
1:02:19
at ACL injuries. We trust you leave feeling significantly
1:02:22
more informed about this prevalent and complex
1:02:24
issue.