Thousands of people each year (More than 250,000 in the US) sustain injury to their ACL in there knee joint and thousands of them undergo ACL reconstruction by surgery. ACL injuries occur most frequently in sports involving pivoting and sudden deceleration (e.g. football, basketball, netball, soccer, handball, gymnastics, downhill skiing). The incidence rate of ACL tears is between 2.4 and 9.7 times higher in female athletes competing in similar activities. ACL tears rarely occur in isolation, more frequent are those occurring in combination with associated injuries, such as cartilage tears or medial collateral ligament (MCL) injuries.
The ACL is one of four main ligaments that stabilise the knee joint and provides nearly 90% of stability to forward translation. An intact ACL stabilises the femur on the tibia and prevents forward translation of the shin bone during agility exercises, jumping, deceleration and pivoting with sudden changes of direction. The ACL is essential for control in pivoting movements. If the ACL is not functional, the tibia may rotate under the femur such as when the person attempts to land from a jump, pivot or stop suddenly.
In ball sports, two common mechanisms cause ACL tears:
- A cutting manoeuvre
- Single-leg landing.
Cutting or sidestep manoeuvres are associated with dramatic increases in rotation moments, as well as deceleration. The typical ACL injury occurs when the foot is planted and you rotate your upper body the aim of suddenly changing direction. Similarly, in landing injuries, the knee is close to full extension (fully straight). The person could be off balance, be pushed or held by an opponent when the injury occurs. Fatigue and loss of concentration may also be relevant factors.
When an ACL injury has occurred the patient often describes an audible ‘pop’, ‘crack’ or feeling of ‘something going out and then going back’. The person is in extreme pain especially in the first few minutes after the injury. The person is often initially unable to continue their activity and this usually associated with large swelling. The person tries to recommence the sporting activity and feels instability or a lack of confidence in the knee.
ACL reconstruction surgery continues to be the gold standard treatment of ACL injuries in the young population. A survey in American academy of Orthopaedic surgeons reported 98% of surgeons would recommend surgery if a patient wishes to return to sport, and 79% believe that an ACL deficient knee will unable to return to all recreational sporting activities without reconstruction. Research of the literature in outcomes after ACL reconstruction states that, surgery does not guarantee athletes return to their pre-injury sport, and return to their previous level of play is unlikely. The risk of developing osteoarthritis is high in the long-term regardless of surgical intervention, and even higher in revision surgery. A recent randomised control study found no difference in young, active individuals between those that had ACL reconstruction compared to those that were treated nonoperatively, with no difference in outcomes between early reconstruction, delayed reconstruction, and no surgery at all. Non-operative management is a viable evidence-based option allowing some athletes to return to sport despite being ACL deficient. However, the decision to undergo early reconstruction is one that should be made by consulting with your surgeon and your physiotherapist and then you can decide together if surgery is required.
Quadriceps strength matters in ACL Rehabilitation
If you decide to undergo surgery or nonoperative management, one of the important things to tick off during rehabilitation amongst other things is quadriceps strength. This component is a little more important than others as I will explain. The difference between the QUAD strength of the injured limb and the non-injured limb is of significant importance. In 2016, a study was published on ACL reconstruction management (Grindem et al., 2016), the authors found 33% of players who returned to sport with <90% strength compared to the non-injured side sustained another knee injury over the next 2 years upon their return to sport. The authors found that for every 1% less than 90% equated to a 3% increased risk of further knee injury over 2 years. This means that if you chose to return to your sporting activity with 80% strength in your injured limb compared to the non-injured limb, it carries a 30% increased risk of further knee re-injury compared to if you returned to sport if you had 90% strength.
Exercises
Squats are one of the most common exercises prescribed to patients during ACL rehab. However, a recent study showed that the ACL reconstruction patient will compensate away from the operated knee for at least 5 months post-op, even when doing body weight squats (Sigward et al., 2018). This study found that at 5 months follow-up, patients will load more evenly between limbs but won’t allow the operated knee to bend as much, putting more work through the glutes. The patients are subconsciously or consciously unloading their operated leg at a time when jumping and high impact activities start.
To overcome this, open kinetic chain exercises such as knee extensions help build strength in the operated leg when done at the right time and range. This evidence supporting open chain exercises is published in 3 papers on ACL reconstruction rehabilitation (Janssen et al., 2018; Van Melick et al., 2016; Wright et al., 2015). I know some people will say open chain exercises such as leg extensions are not ‘functional’ but you will struggle to get good at functional exercises without basic strength. There are other exercises which are extremely important too other than gaining muscle strength such as working on balance and co-ordination exercises which have been used in successful ACL prevention programs.
So in conclusion, surgery is not always the answer when you have injured your ACL, nonoperative management has shown good results but the overall health of the knee joint has to be looked at before you decide to have surgery or not. Exercise rehabilitation is paramount to successful return to play otherwise re-injury risk is high and you will soon be back to square one.
I hope you found this blog useful and if you need any information or education around this topic then please contact me and I will try my best to help. Thank you.
References
Sigward, S. M., Chan, M. M., Lin, P. E., Almansouri, S. Y., & Pratt, K. A. (2018). Compensatory Strategies That Reduce Knee Extensor Demand During a Bilateral Squat Change From 3 to 5 Months Following Anterior Cruciate Ligament Reconstruction. J Orthop Sports Phys Ther, 48(9), 713-718. doi:10.2519/jospt.2018.7977
van Melick, N., van Cingel, R. E., Brooijmans, F., Neeter, C., van Tienen, T., Hullegie, W., & Nijhuis-van der Sanden, M. W. (2016). Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. Br J Sports Med, 50(24), 1506-1515. doi:10.1136/bjsports-2015-095898
Wright, R. W., Haas, A. K., Anderson, J., Calabrese, G., Cavanaugh, J., Hewett, T. E., . . . Williams, G. (2015). Anterior Cruciate Ligament Reconstruction Rehabilitation: MOON Guidelines. Sports Health, 7(3), 239-243. doi:10.1177/1941738113517855
