Commentary
This is a sobering article for those who unfortunately suffered a “game-ending” knee injury either to the meniscus or cruciate ligaments, which is a rather common occurrence amongst the young. Fortunately, surgical reconstruction is often successful in restoring the knee to its normal function, but at a price. In almost all cases of first-time injuries to the anterior cruciate ligament, a substitute ligament is taken from the same knee, either a patellar ligament or a hamstring tendon. It is like “borrowing from Peter to pay Paul”. Hence the injured knee is never the same as before. It goes without saying that intensive rehabilitation is the key to restoring as much function as can be obtained from a doubly–damaged knee. In the young, there is undoubtedly a lot of reserves and good potential for recovery.
So what are the issues to understand for those who have sustained such injuries?
Firstly, a torn meniscus which is repairable should be repaired, but there is a 20-30% chance of reinjury increasing to 50-70% if associated with an unstable ligament injury. An irrepairable torn meniscus will leave the knee compartment with a lack of cushioning that is almost impossible to restore, thus starting the downhill slide to post-traumatic arthritis. Such people should refrain from high-impact and twisting or pivoting sports if they want to preserve their knee-life. Swimming and cycling are appropriate sports to engage in.
Secondly, a torn anterior cruciate ligament (ACL) is very amenable to surgical repair except for the fact that another donor tissue is necessary to replace it. In rare instances, an allograft (tissue taken from a tissue bank) may be used, but their results are not as good, and this is reserved for repeat reconstructions. As the article states, it will be around 9 months of intensive rehabilitation before patients are returned to their pre-injury sporting status.
Thirdly, in 30-60% of young individuals who sustain complete ACL tears, there is potential to avoid surgery and yet allow them to return to contact sports or those requiring pivoting. Why is this so?
The key to preventing re-injury is a combination of normal muscle strength and proprioceptive feedback, together with a dose of common sense. Knee function depends on a balance of quadriceps and hamstring function. After surgery, one or the other is disadvantaged and there is an imbalance of strength causing the knee to buckle and at risk of injuring the repaired structures.
Proprioception (sensation of knee position by the brain) is an automatic process allowing split-second adjustments to body posture to prevent abnormal knee joint distortion. Intact structures provide this feedback and surgery disrupts this positional sense through the loss of sensory nerves. Rehabilitation for injury to joints must always incorporate proprioceptive feedback so the body can sense imbalance and activate the right muscles to counteract this. In simple terms, one cannot afford the time to think about rebalancing, as it must be instinctive. This explains why those who do not undergo surgery for torn ligaments can return to sports at the same level in spite of a clearly unstable knee. The learnt to re-institute bio-feedback in their proprioceptive systems. They are also more conducive and diligent in rehabilitation as they chose to avoid surgery.
Finally, a dose of common sense is required for those who return to sports whether or not they had surgery to repair their ligaments. In other words, they must choose to avoid heavy contact during a game understanding that further injury can mean total cessation of their favourite recreation.
Written by Dr. Khong Kok-Sun, General Orthopaedic Surgeon.
