Arthroscopic anterior cruciate ligament surgery is considered the gold standard treatment for ruptures of the ACL. Without this intervention, it is commonly thought that this injury can lead to functional knee problems such as instability, pain, associated meniscal injuries and, eventually, develop into osteoarthritis that can greatly impact on quality of life.
Among all the wealth of clinical data on ACL reconstruction, there are not many studies into the long-term outcome of ACL reconstruction. Often the injury is compounded by other trauma to the structures of the knee – the meniscus, collateral ligaments and damage to the chondral surface – and these related injuries impact on any evaluation.
One study that has evaluated the long-term outcome of ACL reconstruction surgery was recently published in the American Journal of Sports Medicine. It was authored by the North Sydney Orthopaedic and Sports Medicine Centre, where I undertook a Fellowship in 1996, training under world-renowned knee specialists Leo Pinczewski and Merv Cross.
The first step was to select patients to review; initially 333 patients were identified who had been diagnosed with an ACL rupture. All wanted to return to sports that involved sudden changing of direction or pivoting or were experiencing periods of instability that wasn’t responding to rehab.
The next step was to eliminate any patients that had associated trauma to the knee; other ligament injury, chondral damage or meniscal injury. The clinic then had 90 patients remaining in the study. A standardised operative technique was used as the surgeons performed an isolated reconstruction using patellar tendon autografts. Following on, a standardised post-operative recovery protocol and rehabilitation programme was also prescribed for all patients, including a prohibition on returning to competitive sports that involve pivoting or sidestepping for six to nine months after surgery.
Evaluating long-term outcome of ACL reconstruction surgery
The experts at the North Sydney Orthopaedic and Sports Medicine Centre evaluated the patients first at yearly intervals and then at 10, 15 and 20 years after surgery, offering a really fascinating insight into the longevity of this surgical option. In fact, I was one of the authors of the paper that first reported on these 90 patients, at two years post-surgery.
At 20 years, 36 per cent of patients had sustained another anterior cruciate ligament injury. Interestingly, only 9 per cent re-injured the same knee whereas 30 per cent suffered a ligament rupture in the other knee, with three developing an injury in both.
The highest rate of reinjury was in patients under the age of 18 when the initial procedure was performed – something to bear in mind when treating younger patients with a ruptured ACL.
Another insight that the study gave was the gender differential; women were much less likely to reinjure the reconstructed ACL, possibly because they were far less likely to participate in strenuous activity post-surgery, but they reported worse knee function scores. Kneeling pain was present in the majority of patients and was persistent over 20 years.
ACL reconstruction and prevention of osteoarthritis
The study also evaluated the development of osteoarthritis (OA) in these ACL reconstruction patients as other studies have suggested it can play an important prevention role. Degenerative change was identified using radiography in 27 per cent of patients at five years, 51 per cent at 15 years and had risen to 61 per cent at 20 years. However, only a very low proportion of patients reported moderate to severe symptoms. The suggestion is that ALC reconstruction surgery may not prevent OA but can reduce premature degeneration.