Anterior cruciate ligament (ACL) injuries occur in up to 3% of recreational athletes and as many as 15% of professional athletes. ACL ruptures are seen most commonly in sports that involve pivoting and change of direction, for example AFL, netball and skiing. With the increasing popularity of female participation in Australian Rules football, it has been widely acknowledged that females have a significantly higher risk of ACL rupture, with some research papers suggesting this risk to be up to 8 times greater compared to males.
In Australia and in particular in Melbourne, being the AFL capital of the country, ACL ruptures are often managed with reconstructive surgery, where a portion of tissue (commonly the hamstrings tendon) is harvested to create a graft in place of the injured ligament. Over time, the graft changes in physiology to strengthen and perform the role that the original ACL performed, namely providing stability to the knee joint. Surgery, however, is just the beginning of the journey in recovering from an ACL injury. In addition to regaining the obvious strength deficits that result from having surgery, it is becoming more and more evident that a lot of time needs to be focused on neuromuscular control. There are neurological receptors within the ACL that are responsible for the neural control of the knee, i.e. knowledge of where the knee is in space (proprioception) and muscle strength and activation.
While many people talk about recovery from an ACL injury to be a blanket 12 month process, this is not entirely accurate. Some elite athletes make a successful return to play after 9 months, while others may take up to 2 years off sport. In addition, an initial ACL injury results in up to a 22% risk of re-injuring the same ACL and up to a 24% risk of rupturing the opposite ACL. Thus the question begs – what determines when an athlete can return to sport following an ACL reconstruction? Or, perhaps a more accurate question should be: when is an athlete safest to return to sport with the lowest possible risk of a subsequent ACL injury?
The answer is by following a criterion-based approach to rehabilitation. This involves having a number of objectively measurable quantitative assessments that are continually used during the rehabilitation process to determine how to best progress. A physiotherapist will generally split up the recovery process into phases. These outcome measures will then be used to determine whether or not an athlete is ready to progress to the next phase. An example of which would be regaining full range of motion, regaining equal quadriceps strength or regaining equal balance. Once all the boxes of one phase have been ticked, the athlete may enter the next phase in the rehabilitation process. These measures are gradually progressed to reflect the demands of a particular sport, for example cutting and changing direction or landing from a jump. Once the athlete has successfully achieved the highest outcome measures, they may be deemed to have done enough preparation for a safe return to playing sport at the desired level. This criterion-based approach may take 9 months, it may take 12 months or it may take longer. But to minimise what is a relatively high risk of re-injury, it is imperative that the rehabilitation process is followed based on achieving these outcome measures rather than on a time-based approach.
van Melick, N., van Cingel, R.E.H., Brooijmans F., Neeter, C., van Tienen, T., Hulleigie, W., and Nijhuis-van der Sanden, M.W.G. (2016). 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, 50, 1506-1515.