Part of ACL reconstruction rehab
Preventing a second ACL injury: the risk, and what you can change
Warning signs, and when to get help
How often does a second ACL injury happen?
Often enough to take seriously, and the answer is a set of numbers, not one. Every percentage you will read on this subject belongs to a particular group of people followed for a particular length of time, and swapping one group's figure for another is how this topic gets misreported.
A systematic review and meta-analysis of secondary injury after ACL reconstruction took in 19 studies, and pooled different subsets of them for each figure it reports. Across all the patients in the 7 studies that reported both knees, the pooled rate of a second ACL injury was 15% (95% CI 10% to 22%). The pooled rate on the operated side, from 14 studies, was 7% (95% CI 5% to 8%), and on the other side, from 7 studies, 8% (95% CI 5% to 13%).
The subgroups ran higher. In a younger group under 25 the total was 21% (95% CI 16% to 27%) from 6 studies. In athletes who returned to sport it was 20% (95% CI 14% to 27%), also from 6 studies. In those who were both under 25 and back in a high-risk sport, it was 23% (95% CI 16% to 30%) (Wiggins and colleagues, 2016).
None of those figures is a slice of another. Each is pooled from its own set of studies, so the 15% is not the 7% and the 8% added together, even though they happen to add up to it.
One detail decides how those figures can be used. The studies pooled in that review followed people for very different lengths of time, from 12 months after return to play in one to a minimum of 15 years in the longest, and the review puts the wide spread of published rates, which it gives as 3% to 29.5%, down to studies mixing age ranges, follow-up periods and activity levels. So 23% is not a chance per season, and it is not a two year risk. It is the proportion of a particular kind of patient, in a particular set of studies, who were recorded as injuring an ACL again at some point.
The clearest fixed window comes from a separate cohort. Seventy-eight athletes aged 10 to 25 at the time of their reconstruction, all cleared to return to level 1 or 2 pivoting and cutting sport for at least 50 hours a year, were followed for exactly 24 months after they went back. In that time 23 of them, 29.5%, had a second ACL injury, which was 5.71 times the rate in 47 uninjured athletes from the same sports (95% CI 2.0 to 22.7). The average time from going back to sport to the second injury was 215 days (Paterno and colleagues, 2014).
If you are 40 and going back to cycling and the gym, none of the above was measured on you. Those numbers describe teenagers and young adults going back to cutting and pivoting sport, which is the highest risk group anyone has studied.
If you are in that group and those figures have frightened you, say so at your next appointment instead of carrying it on your own. Being afraid of injuring the knee again is common, and the Aspetar guideline treats it as something to measure and work on, not as a character flaw. The end of this page says what that work looks like. And nothing here is a prediction about your knee: the two things on this page that moved with something a person actually did were thigh strength before going back and how long they waited.
Which knee is at risk, and when
Both of them, and in the studies with the tightest follow-up the other knee came off worse.
In the pooled figures, the operated side and the other side were close: 7% against 8% overall, and 10% against 11% in those under 25 (Wiggins and colleagues, 2016). In the 24 month cohort the gap was wider, with 16 of the 23 second injuries in the opposite knee, 20.5% of all the athletes, against 9.0% who retore the graft (Paterno and colleagues, 2014).
Timing gets stated more confidently than the evidence allows. That cohort reports an average of 215 days from return to sport to the second injury. It also counted how many games and practice sessions each athlete took part in, which it calls athlete exposures, and 12 of the 23 second injuries, 52%, happened inside the first 72 of them. For a competitive athlete in season, the authors say that can be as little as 12 weeks after going back (Paterno and colleagues, 2014).
So the early months back are the loaded ones. What that cohort does not do is report the timing separately for graft retears and for opposite knee injuries, so on its own it cannot tell you whether one comes earlier than the other.
A longer series can. Among 673 people followed for a minimum of 15 years after reconstruction by a single surgeon, expected survival of the graft was 95% at 2 years, 93% at 5 years, 91% at 10 years and 89% at 15 years, while expected survival of the other knee's own ACL was 97%, 93%, 90% and 87% at the same points (Bourke and colleagues, 2012). Read across those two lines: in the first years the graft is the one more likely to go, and by 15 years the other knee has drawn level and passed it. That was a consecutive surgical series rather than a selected group of young pivoting sport athletes, so the curves describe its own population and not a teenager going back to soccer.
What it changes in practice is simple enough. Your prevention work is for both legs. If your physio is only testing the operated side, ask about the other one.
What makes a graft fail
The graft in your knee is not the ligament you were born with. It is a tendon, usually one of your own, put where the ligament was, and it then goes through a long biological change that surgeons call ligamentization. A systematic review of the human biopsy studies found that these grafts stay alive through that process, and that a mature graft can look much like a normal ACL down a microscope while keeping real differences in how its collagen is arranged.
The part that matters for you is the last finding: the stages are described, but there is no agreement on their timeframe (Claes and colleagues, 2011). Only four human studies existed to review, none above level 3 evidence.
So nobody can give you the date your graft is finished. If you are told a month at which it is as strong as an undamaged ligament, that figure is not coming from human evidence. It is one reason return to sport is decided on testing and on how the knee behaves rather than on the calendar alone, and it is why your own surgeon's timeline comes before anything written here.
A graft fails mechanically, and usually the way the first ligament went: a pivot, a fast change of direction, a landing, often with nobody touching you. Every first injury in that 24 month cohort had been a noncontact or indirect contact one, because contact injuries were excluded, and in the 24 months that followed not one of the second injuries came from direct contact with the leg either (Paterno and colleagues, 2014).
The 15 year series turned up two findings you cannot act on but should know about. A family history of ACL rupture doubled the odds of both graft rupture and a rupture of the other knee's ACL. Graft choice made no significant difference to graft survival in that series, 88% for hamstring against 91% for patellar tendon, although patellar tendon grafts carried a higher risk to the opposite knee (Bourke and colleagues, 2012). Which graft you have and who is in your family are settled. What you do with strength, landing and timing is not.
What raises the risk, and what you can change
Two of the main risk factors are fixed, and the rest of the list is the reason this page exists.
The fixed ones are age and the sport you want to play. The meta-analysis concluded that younger age and a return to a high level of activity are the factors most clearly associated with a second ACL injury, and that when one happens it is likely to come early in the return to play period (Wiggins and colleagues, 2016). Being 17 and playing a cutting sport is a different proposition from being 35 and playing tennis doubles, and no amount of training makes those the same.
The ones you can work on are strength, control and timing. Thigh strength closer to the other leg before going back went with fewer reinjuries in a cohort of 106 pivoting sport athletes (Grindem and colleagues, 2016). How you land and change direction is trainable. When you go back, and whether you meet criteria first, is a decision rather than a fact, and it is covered in ACL return to sport testing.
Whether passing those tests actually lowers the risk is still argued over, and the Aspetar guideline lays the disagreement out rather than resolving it. Of the four reviews it looked at on this question, one meta-analysis concluded that passing current return to sport criteria reduced the risk of graft rupture, another found a lower rate of graft rupture but no effect on the other knee, a third found that a combination of functional tests and self-reported function with set cut-off points went with fewer reinjuries, and a fourth found no statistically significant association at all. The guideline points to imprecise pooled estimates and differing ages and competition levels as the reason. Read it the right way round: passing the tests is not a certificate, and failing them is a reason to keep working, not a reason to go back anyway.
There is one trap here. A symmetrical hop distance can sit on top of a knee that is still doing far less than its share: in 26 male athletes already cleared to return to sport, hop distance was 97% of the other leg while the operated knee's work during push off was 69%, with the difference made up at the hip and trunk (Kotsifaki and colleagues, 2022). Feeling ready and measuring ready are not the same thing, and the knee is good at hiding a weakness.
Does delaying return to sport help?
In the best cohort on the question, yes, up to about 9 months.
Among 106 people who played pivoting sports and had an ACL reconstruction, those who went back to level 1 sport had a reinjury rate 4.32 times higher than those who did not. The rate of injuring the knee again fell by about half for each month the return was delayed, up to 9 months after surgery, and no further reduction was seen after that. More symmetrical thigh strength before going back also went with fewer reinjuries (Grindem and colleagues, 2016).
That is one cohort of 106 people, not a trial, and it is the single most quoted finding in this field, so treat it as a strong signal rather than a law. It sits alongside the van Melick guideline's advice that rehab carries on for 9 to 12 months after surgery (van Melick and colleagues, 2016), and alongside the uncomfortable fact that the early months back appear to be the highest risk ones.
On these figures, the months spent waiting and training cost less than the months that follow a second injury. That is the trade most people are actually choosing between.
The training used to lower the risk
Strength, landing, change of direction, and then keeping all three going. Not finishing them.
The work itself is the later stages of the ACL reconstruction rehab program, and ACL rehab exercises by phase sets out the order. What comes next matters more than the list does, though, because any one of those paragraphs can mean that none of it belongs to you yet.
The stage you are at comes first. These are late stage exercises, meant for a knee that has already come through the earlier stages and been tested, not for the first weeks or months after an operation. Hopping and landing work belongs to the stage your physio opens, which in most programs is at least about 3 months after surgery and only after testing. After a hamstring graft or a quadriceps tendon graft that date is later again, at least 16 weeks after surgery unless your surgeon or physio has cleared it earlier, because the place the tendon was taken from is still rebuilding (Briem and colleagues, 2026).
Resisted hamstring work has its own hold after a hamstring graft, which matters here because the eccentric curl below is the heaviest version of it. Keep all added resistance off the hamstring, and read the 4 week mark as the point below which loading has been reported to tear the healing tendon rather than as the date you may start adding it: weight goes on at 12 weeks unless your own team gives you an earlier date (Briem and colleagues, 2026; Högberg and colleagues, 2026). If a meniscus or cartilage was repaired in the same operation, get your surgeon's go-ahead before any hopping, landing or twisting, and before any deep or loaded bending such as a full squat, a lunge or kneeling, because those limits often run for months after a repair and are lifted later than the ones on walking.
Jumping and hopping also load the joints, the bones and the pelvic floor. If you have osteoporosis or have had a fall in the past year, ask your physio before you do any hopping. If you have had a hip or knee replacement, get the go-ahead from your surgeon before you try hopping. Many surgeons advise against jumping and hopping after a joint replacement for good, not just for the first months, because each landing sends high impact through the new joint. If you are pregnant, have had a baby in the past year, or leak urine when you jump, cough or sneeze, check with your midwife or physio before you start this stage. Stop the hopping and speak to your physio if urine leaks while you are doing it, or if you feel pressure or heaviness low in your pelvis. After having a baby, postnatal guidance usually leaves jumping and hopping until at least 3 months after the birth, once a pelvic floor check shows you are ready. With a heart condition or high blood pressure, check with your doctor before you start.
This page is for adults. A child or teenager who has had ACL surgery should follow the plan from their surgeon and physio, and ask them before trying any exercise on this page. The figures earlier on this page come from studies of teenagers and young adults, but the exercises in this section are late stage work that a young person's own physio opens.
With those read, here is the work itself. The pieces most often kept on after discharge are loaded single leg strength such as the split squat, hamstring work such as the eccentric hamstring curl, sideways loading such as the side to side squat and lateral knee stability with a band, and landing and direction change such as skater hops, the drop landing and the single leg hop and hold. Everything named there is late stage work, for a knee that has already been through the earlier stages and tested, and your physio is the one who opens each piece of it.
As a rough guide, the strength exercises in the later stages often use 2 to 3 sets of 6 to 15, and hopping starts with small numbers, such as 1 to 3 sets of 5 to 10 single leg hops a few times a week and not on two days in a row, rather than long sessions of it. Landing from a step, as in the drop landing, is usually kept to once or twice a week with a full rest between sets. Set the hopping and landing work up the way each exercise page describes it: a non-slip floor, shoes that grip rather than socks, a clear space, something solid within reach, and a low step rather than a high one for the drop landing. Your physio will set the numbers and change them as you go.
There is a limit to all of it. The best evidence synthesis of rehabilitation after ACL and meniscal injury, produced for the OPTIKNEE consensus, reports that not one of the systematic reviews it covered had assessed reinjury prevention, and rated the overall evidence as low. What it did find was that neuromuscular control exercise, two to three sessions a week over 1 to 9 months, was more effective than standard rehabilitation for thigh and hamstring strength and for self-reported function, at very low to low certainty, and that adding electrical muscle stimulation to standard rehabilitation improves quadriceps strength in the first 4 to 12 weeks after surgery, at moderate certainty (Culvenor and colleagues, 2022). That last one is an early weeks finding, not anything to do with the long term work this section is about.
So the claim this page makes is the one the evidence supports: this training improves the things that go with fewer reinjuries. It is not proven to prevent one. That is still a better bet than stopping, and the people who keep a twice weekly strength session for years are the ones who tend to still have a knee they trust.
Load from the rest of your sport counts too. Knee problems in pickleball and strength work for runners cover two common returns, and how running is reintroduced covers the step before either.
Do knee braces prevent a second ACL injury?
No study has shown that they do, and the subject has barely been tested for that question at all. Both halves of that sentence matter.
The OPTIKNEE synthesis found moderate certainty evidence that knee bracing after an ACL reconstruction gives no benefit for knee laxity or physical function, drawing on a systematic review of seven randomized trials, and reported that none of the reviews it covered had assessed reinjury prevention (Culvenor and colleagues, 2022). A systematic review of 15 studies of functional bracing after ACL reconstruction, with follow-up from 3 to 48 months, concluded that the evidence for routine functional bracing to bring the reinjury rate down is limited. That same review is not dismissive of braces in general: it reported that bracing may help the mechanics of how the knee moves, and may give the graft some added protection, without costing function, range of movement or the knee's sense of its own position (Lowe and colleagues, 2017). The same review reports one cost that matters if you are wearing a brace through your rehab: bracing may lower how much the thigh muscle switches on, even though it did not change the functional tests. Those are laboratory and movement findings rather than counted second injuries, which is the gap in all of this.
What that does not mean. If your surgeon prescribed a brace, wear it exactly as they told you. A prescribed brace is often there for something specific, such as a meniscus or cartilage repair or a graft that needs protecting through a particular range, and this page knows nothing about your operation. Taking off a brace on the strength of a research summary is the wrong way round, and the conversation belongs with the team who fitted it.
If you simply want one for confidence, that is a legitimate thing to ask your physio about, not something to settle from a product page. Our pages on knee braces for osteoarthritis and knee braces for a meniscus tear cover what the different types do and do not do.
The signs of a second tear, and what to do that day
A second ACL injury usually announces itself. A pop, a shift or a feeling of the knee coming apart, on a landing or a turn, and then swelling within a few hours.
That pattern is a same day matter, not a wait and see one, and the warning signs at the foot of this page give it its own line along with where to go. It makes no difference which knee it happened to. A graft tear and a fresh tear in the other knee feel much the same at the moment they happen, and both take the same route on the same day, so do not wait on the grounds that it was the good side. The same is true of a knee that locks, and of a knee that suddenly will not straighten when it could before. Why a knee gives way and a swollen knee cover the slower versions of both, and the ACL warning signs page sets out what belongs to your surgeon rather than to your physio.
Two things about what follows. A second ACL injury is not automatically a second reconstruction, and that decision is made the same way the first one was, on your knee, your symptoms and what you want to do. And a twist or a fall that damages the graft can damage a meniscus or a meniscus repair at the same time, which is why the assessment looks at the whole knee rather than at the ligament alone. Knee osteoarthritis covers the longer term question that people usually ask next.
If the fear of it happening again is sitting on you, say so to your physio. The Aspetar guideline notes that fear of injuring the knee again is the biggest reason people do not return to sport, and it is treated as a finding, not a personality trait: there are questionnaires that measure it and specific work that addresses it.
This page is general education and not advice about your own knee, and it does not stand in for your post-operative appointments. What your knee can take, and when, belongs to the people who can examine it. Where anything here differs from what your surgeon or your physio has told you, follow them, because they know your graft, whether a meniscus was repaired alongside it, and what they found when they were inside the joint.
Related exercise programs
Warning signs
Get emergency help now
- Emergency: sudden, severe pain in your lower leg that is much worse than you would expect, especially with a tight bandage or brace on the leg. It may come with a tight, swollen leg, pain that gets worse when the muscle is stretched, numbness, pins and needles or weakness. Call emergency services or go to an emergency department straight away, and do not drive yourself. This can be acute compartment syndrome, which needs urgent surgery.
- Emergency: since your operation, you suddenly become short of breath, you get chest pain or pain in your upper back that may be worse when you breathe in, you cough up blood, your heart is beating very fast, or you faint. Call emergency services straight away, even if your leg looks normal. These can be signs of a blood clot in the lungs (pulmonary embolism).
Get help today
- Same day: a calf or thigh that is newly swollen or getting more swollen, warm, tender, red or darker than usual, has swollen veins that are sore to touch, or has a throbbing or cramping pain that does not fit your injury or condition, or that feels different from normal muscle soreness after exercise. This can be a sign of a blood clot (deep vein thrombosis), especially after surgery, an injury, time in a cast or boot, a long trip or a spell of being much less mobile than usual. Get medical advice the same day. If you are also short of breath or have chest pain, call emergency services.
- Same day: since your operation, your wound is oozing, leaking or has pus coming out of it, or its edges start to come apart, or your knee is tender, swollen, painful or red and it is not getting better or is getting worse, or you have a high temperature or feel hot and cold or shivery. Redness can be harder to see on brown or black skin. Contact your surgical team the same day, or get urgent medical advice if you cannot reach them. These can be signs of an infection in the wound or the knee joint. If you feel very unwell, go to an emergency department. If you have a very high or very low temperature, shivering you cannot control, you are breathing very fast or finding it hard to breathe, you are confused or your speech is slurred, your skin, lips or tongue look blue, gray, pale or blotchy (on brown or black skin this can be easier to see on the palms of the hands or soles of the feet), or you have a rash that does not fade when you press it, call emergency services, as this can be sepsis.
- Same day: your knee swells up quickly over a few hours and feels tight and full, with more pain than the day before, and there was no fall, twist or pop to explain it. This can happen while your temperature is normal and the wound looks fine. Contact your surgical team the same day, or get assessed the same day at urgent care or an emergency department if you cannot reach them. Bleeding into the joint and an early infection inside the joint can both look like this from the outside, and a knee that is hot to touch, or a temperature alongside it, makes an infection more likely. Do not wait for a call back if either is there. If you feel very unwell, go to an emergency department.
- Same day: your knee gives way, or you feel a pop, a shift or a twist inside it, and it swells up within a few hours or is very painful. Keep your weight off it and contact your surgical team, or get assessed the same day at urgent care or an emergency department. A fall or a twist can damage the new ligament (graft) or a meniscus repair. If the knee looks out of shape, or your foot turns numb, cold or pale, go to an emergency department straight away, and do not drive yourself. If the knee only feels a little unsteady now and then, with no swelling or pain, it is not an emergency, but tell your physio or surgeon in the next few days.
- Same day: the knee is locked, which means it is stuck bent and you cannot straighten it, even after gently trying to move it, or it suddenly will not bend or straighten as far as it did before. Contact your surgical team, or get assessed the same day at urgent care or an emergency department. A torn piece of meniscus can get caught in the joint and block it. This is different from the slow, gradual stiffness of the early weeks.
- Same day: you suddenly cannot straighten your knee by yourself or lift your leg straight when you could before, often after a pop, a fall or a stumble, or you notice a dip or a gap just above or below your kneecap. Keep your weight off it and contact your surgical team, or get assessed the same day at urgent care or an emergency department. After a patellar tendon or quadriceps tendon graft, the tendon or the kneecap near where the graft was taken can rarely tear or break.
- Same day: a leg or foot that is getting weaker, for example your foot drags, catches on the ground or slaps down when you walk (foot drop). Get medical advice the same day. If the weakness is getting worse by the hour, go to an emergency department.
- Same day: new numbness, tingling or burning in your lower leg or foot, beyond the numb patch of skin near your scars. Contact your surgical team or get medical advice the same day. If it started after a fall or an injury, or your foot or toes turn cold, pale, blue or gray, call emergency services or go to an emergency department straight away, and do not drive yourself.
Book an appointment
- Within a few days: your knee still will not straighten as far as the other one, or bend as far as your physio expects, and it is not improving from week to week, or it is slowly losing movement it had. This is not an emergency, but contact your physio or surgeon within the next few days. Tell them if the knee feels blocked right at the end of straightening, or clunks or hurts there, rather than simply feeling tight, and tell them if it stops short of straight in the months after your operation. A small lump of scar tissue at the front of the knee (a cyclops lesion) can block the last few degrees, and when it does it usually shows up 3 to 6 months after surgery. It is uncommon, most surgeons treat it first with rehab aimed at straightening, and a short keyhole operation to remove it is kept for a knee that stays stuck (D'Ambrosi and colleagues, 2026). Stretching harder is not the answer either way. Getting the knee fully straight is one of the first aims of rehab.
Common questions
How likely is a second ACL injury after surgery?
It depends on your age, your sport and how long you are followed, which is why single percentages are so often quoted wrongly. A meta-analysis that took in 19 studies pooled a secondary ACL injury rate of 15% (95% CI 10% to 22%) across all the patients in the 7 studies that reported both knees, rising to 21% in a younger group under 25, 20% in athletes who returned to sport, and 23% in those who were both under 25 and back in a high-risk sport (Wiggins and colleagues, 2016). Each of those figures comes from a different subset of the studies, and the studies followed people for anything from 12 months to a minimum of 15 years, so none of them is a rate per season or a risk over two years. In a cohort of 78 athletes aged 10 to 25 followed for exactly 24 months after returning to pivoting and cutting sport, 29.5% had a second ACL injury, about 5.7 times the rate in uninjured athletes from the same sports (Paterno and colleagues, 2014). If you are older than that group, or going back to a sport without cutting and pivoting, none of those figures was measured on people like you.
Is my other knee at risk as well?
Yes, and in some studies more so than the reconstructed one. In the pooled figures, the ipsilateral rate was 7% (95% CI 5% to 8%) and the contralateral rate 8% (95% CI 5% to 13%), and among patients under 25 the two were 10% and 11% (Wiggins and colleagues, 2016). In the cohort followed for 24 months after returning to sport, 16 of the 23 second injuries were in the other knee, which was 20.5% of all the athletes, against 9.0% who retore the graft (Paterno and colleagues, 2014). Timing differs between the two. In a series followed for a minimum of 15 years, expected survival of the graft was 95% at 2 years against 97% for the other knee's own ACL, and by 15 years that had reversed to 89% against 87% (Bourke and colleagues, 2012). The practical consequence is that your rehab and your prevention work are for both legs, not for the operated one, which is also why your physio keeps testing the other side.
What are the symptoms of a second ACL tear?
Usually a sudden event rather than a gradual change: a pop, a shift or a feeling of the knee coming apart, often on landing or turning, followed by the knee swelling within a few hours and sometimes by not trusting the leg afterward. That combination needs your surgical team the same day, and the warning signs on this page say exactly what to do and where to go. A knee that locks, or that suddenly cannot be straightened, needs the same day route too. A knee that feels a little unsteady now and then, with no swelling and no pain, is not an emergency, but it should be reported to your physio or surgeon in the next few days rather than ignored.
Does a knee brace prevent a second ACL injury?
There is no evidence that it does, and that is different from evidence that it does not. A best-evidence synthesis produced for the OPTIKNEE consensus found moderate certainty evidence that knee bracing after an ACL reconstruction provides no benefit for knee laxity or physical function, and reported that none of the systematic reviews it covered had assessed reinjury prevention at all (Culvenor and colleagues, 2022). An earlier review of 15 studies concluded that the evidence for routine functional bracing to bring the reinjury rate down is limited, while also reporting that a brace may help the mechanics of how the knee moves and may give the graft some added protection (Lowe and colleagues, 2017). So a brace has not been shown to lower the rate of a second injury, and nobody has really tested it for that. If your surgeon prescribed a brace, keep wearing it as they told you: nothing here is a reason to take off a brace somebody put you in.
Can exercises prevent a second ACL injury?
They can change the things that go with a lower rate, which is the most honest way to put it. Thigh strength closer to the other leg before going back went with fewer reinjuries in one cohort of 106 pivoting sport athletes (Grindem and colleagues, 2016), and strength and landing control are what the training targets. What has not been shown is that any program prevents a second injury: the OPTIKNEE synthesis found that not one of the systematic reviews it covered had assessed reinjury prevention (Culvenor and colleagues, 2022). The sensible position is to keep doing the work, keep it going after you are discharged rather than stopping at the end of rehab, and treat it as odds-lowering rather than as a shield.
References
- Wiggins AJ, Grandhi RK, Schneider DK, Stanfield D, Webster KE, Myer GD. Risk of Secondary Injury in Younger Athletes After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis. American Journal of Sports Medicine. 2016;44(7):1861-1876. https://doi.org/10.1177/0363546515621554
- Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of Second ACL Injuries 2 Years After Primary ACL Reconstruction and Return to Sport. American Journal of Sports Medicine. 2014;42(7):1567-1573. https://doi.org/10.1177/0363546514530088
- Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. British Journal of Sports Medicine. 2016;50(13):804-808. https://doi.org/10.1136/bjsports-2016-096031
- Bourke HE, Salmon LJ, Waller A, Patterson V, Pinczewski LA. Survival of the anterior cruciate ligament graft and the contralateral ACL at a minimum of 15 years. American Journal of Sports Medicine. 2012;40(9):1985-1992. https://doi.org/10.1177/0363546512454414
- Claes S, Verdonk P, Forsyth R, Bellemans J. The "ligamentization" process in anterior cruciate ligament reconstruction: what happens to the human graft? A systematic review of the literature. American Journal of Sports Medicine. 2011;39(11):2476-2483. https://doi.org/10.1177/0363546511402662
- Culvenor AG, Girdwood MA, Juhl CB, et al. Rehabilitation after anterior cruciate ligament and meniscal injuries: a best-evidence synthesis of systematic reviews for the OPTIKNEE consensus. British Journal of Sports Medicine. 2022;56(24):1445-1453. https://doi.org/10.1136/bjsports-2022-105495
- Lowe WR, Warth RJ, Davis EP, Bailey L. Functional Bracing After Anterior Cruciate Ligament Reconstruction: A Systematic Review. Journal of the American Academy of Orthopaedic Surgeons. 2017;25(3):239-249. https://doi.org/10.5435/JAAOS-D-15-00710
- Kotsifaki R, Korakakis V, King E, et al. Aspetar clinical practice guideline on rehabilitation after anterior cruciate ligament reconstruction. British Journal of Sports Medicine. 2023;57(9):500-514. https://doi.org/10.1136/bjsports-2022-106158
- van Melick N, van Cingel REH, Brooijmans F, et al. Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. British Journal of Sports Medicine. 2016;50(24):1506-1515. https://doi.org/10.1136/bjsports-2015-095898
- Briem K, Zebis MK, Haraldsson BÞ, Bencke J, Fernandes L. Rehabilitation guidelines after autograft anterior cruciate ligament reconstruction need more graft-specific exercise recommendations: A scoping review. Knee Surgery, Sports Traumatology, Arthroscopy. 2026;34(1):83-101. https://doi.org/10.1002/ksa.12666
- Högberg J, Wernbom M, Hamrin Senorski E. Can we rebuild what has been taken? A narrative review of biological and functional consequences of hamstring tendon harvest in ACL surgery. Science Progress. 2026;109(3):00368504261461371. https://doi.org/10.1177/00368504261461371
- Kotsifaki A, Whiteley R, Van Rossom S, et al. Single leg hop for distance symmetry masks lower limb biomechanics: time to discuss hop distance as decision criterion for return to sport after ACL reconstruction? British Journal of Sports Medicine. 2022;56(5):249-256. https://doi.org/10.1136/bjsports-2020-103677
- D'Ambrosi R, Helito CP, Della Villa F, et al. Practice patterns, controversies, and proposed management algorithm for cyclops syndrome after anterior cruciate ligament reconstruction: An international survey. Journal of ISAKOS. 2026;19:101165. https://doi.org/10.1016/j.jisako.2026.101165
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Written and checked by the PocketPhysio editorial team. Last updated 2026-10-24.
This page is general education, not a diagnosis or a personal treatment plan. See a physiotherapist or doctor for advice about your own situation.