Hi guys, Kate here, Performance Coach at Absolute William Street. Before moving to Australia I was working with Olympic athletes in Hong Kong, and have now moved to Melbourne for my PhD in Sports Medicine with Victoria University. ACL rehabilitation has been my all-time favorite topic to talk about, growing up as an amateur athlete I ruptured my ACL (10 years ago), so I know how it feels, physically and mentally. The knee has been great so far, and I’m able to enjoy knee strenuous activity such as soccer and snowboard without issue.
How did I tear it? I was playing rugby and was being tackled from the side while I was running with the ball. The impact was so high that I injured my knee before landing. This is different from the most common ACL injury mechanism- where they are non-contact. Usually ACL injury happen when one attempts to change direction, turn and pivot with the foot in stuck in the ground (ouch!).
ACL injuries are common in sports that involve sudden stops and change in direction, jumping and landing, such as football, soccer, basketball, netball and skiing. Many people will hear a “pop” sound, followed by intense pain and instability (yes I’m one of them…).
Depending on the severity of the ACL injury (e.g. complete tear vs partial tear) and if other structures are damaged (e.g. meniscus), there are different rehabilitation protocols to help regain strength and stability and ultimately return to play (RTP) and doing the things you love.
Currently I’m doing research on the topic of RTP of lower limb injury and I thought it might be good to share more about ACL RTP criteria, as a lot of times patients will ask us when he/she can return to doing what they love.
Indeed, this is a challenging question because as practitioner not only do we want the athlete to return to previous performance level, but we must also minimize risk of subsequent injury. Ardern et al  had shown that on average 80% of patients returned to sport, while only 55% returned to competitive levels after ACL reconstruction surgery. This highlights the fact that successful RTP is challenging.
Whenever I get an athlete on the path of ACL rehabilitation, I will make sure I set expectations right away. Depending on the sports they play, most of the time I would not clear anyone before 9 months (preferably 12 months plus!). Building on previous studies  which showed 51% increased risk of knee re-injury for every month an athlete returned to sport earlier than 9 months, a recent paper by Beischer et al  showed that young athletes who returned to “knee strenuous sport” earlier than 9 months were associated with an approximately 7-fold increased rate of sustaining a second ACL injury! So, don’t try to rush back to sports without going through your whole ACL rehabilitation program. And it’s not just about time frames but ensuring RTP criteria are met physically and mentally.
While time for the graft to heal before returning to play is important, clinical and functional assessment is equally important [4-6], this includes:
- Full functional stability, full range of motion, no knee effusion (swelling)
- Quadriceps strength compared to the uninvolved >90% LSI (Limb Symmetry Index)
- Hamstrings to quadriceps ratio 0.6 (some controversy for the ratio)
- Single broad jump distance, triple hop distance > 90% of the uninvolved side
- Agility test (running T-test)
- Sports specific test relevant to the patient
- Load management – accumulating enough training load (chronic training load) can help the patient cope with training sessions (acute load) upon return to play, which in turns enhance performance and reduce subsequent injury risk.
- Movement quality
You might expect after passing the above criteria and receiving medical clearance, one would be ready to return to play, happily, eagerly, and ultimately safe right? Surprisingly, this may not always be the case. In one study by Langford et al , despite all participants (n=87) have received medical clearance to return to sport, only 51% resumed full competition 12 months following surgery. It may be due to change in lifestyle or psychologically readiness, that can include lack of confidence or fear of re-injury. I can totally understand that because no one wants to go through the 9 months rehabilitation again by choice, not to mention having to use those damn crutches again! For these reasons, assessment of these factors must be included in the management plan.
In fact, fear avoidance model, self-efficacy theory, stress, social support, and athletic self-identity explain failure to return to sport in athletes with full level of function and are predictive of outcomes after surgery.
Therefore, as a practitioner, I try to address the fear by the following:
- Keep the momentum – encourage athletes to stay around the sporting club during rehabilitation periods. Even they actively participate in full play/training, they could do rehabilitation exercise at the side and do some modified training. This helps with some of the social isolation element, which are factors in mental health issues associated with injury.
- Challenge their belief – give them the right training and confidence to perform fearful movement physically and mentally.
- Improve their fitness level, including aerobic, anaerobic, power and strength. Research has shown that fitter athletes maybe less prone to injury. 
- Perform sports specific training and testing every month during the rehabilitation. This helps to build confidence as they see progress.
- Ongoing patient education about the process, goal setting and frequent feedback.
- Individualisation of the rehabilitation plan – while there are obvious key metrics to meet, a cookie cutter approach won’t work, everyone is different!
Touch wood, we don’t want you to get injured. But if injury happen, we are always here to help and assist you to return to play.
Written by Master Coach & Registered Physiotherapist Kate Yung at Absolute William St
- Ardern, C.L., et al., Fifty-five per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and meta-analysis including aspects of physical functioning and contextual factors. British Journal of Sports Medicine, 2014. 48(21): p. 1543-1552.
- Grindem, H., et al., 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): p. 804-808.
- Beischer, S., et al., Young Athletes Who Return to Sport Before 9 Months After Anterior Cruciate Ligament Reconstruction Have a Rate of New Injury 7 Times That of Those Who Delay Return. Journal of Orthopaedic & Sports Physical Therapy, 2020. 50(2): p. 83-90.
- Blanch, P. and T.J. Gabbett, Has the athlete trained enough to return to play safely? The acute:chronic workload ratio permits clinicians to quantify a player’s risk of subsequent injury. British Journal of Sports Medicine, 2016. 50(8): p. 471-475.
- Kyritsis, P., et al., Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. British Journal of Sports Medicine, 2016. 50(15): p. 946-951.
- Buckthorpe, M., Optimising the Late-Stage Rehabilitation and Return-to-Sport Training and Testing Process After ACL Reconstruction. Sports Medicine, 2019.