The anterior cruciate ligament (ACL) is a major ligament deep inside the knee. It is commonly torn during sport and once torn, it usually does not heal. An ACL deficient knee is often unstable, leading to “giving way” on certain movements. Previous attempts (1960’s and 70’s) to repair the ligament did not lead to good results. Later, attempts to repair the ligament were abandoned in favour of a reconstruction in which the torn ligament is replaced with some normal tissue (part of the patella ligament or some hamstring tendons). It is a very common injury and reconstruction is a common procedure for orthopaedic surgeons. If you only want information about the procedure, there are thousands of websites that will help you. If you want to know whether the surgery is necessary, read on.
If you are young and active and have an acute ACL tear, you will almost certainly be advised to have a reconstruction. There is geographical practice variation, but in countries where the surgeon is paid to perform the surgery, you will almost certainly be advised to have a reconstruction.
Several clinical trails have been published over the years. Studies of operatively versus non-operatively treated ACL injuries using outdated techniques (here and here) showed no difference between the treatment groups. But somewhat surprisingly, this 2008 non-randomised trial of reconstruction compared to non-operative treatment also showed no difference. And this comparative study from 2009 with 10 year follow up (again without randomisation) showed no difference between reconstruction and non-operative treatment.
What we needed was a randomised trial reflecting the two treatment options currently available: have the ligament reconstructed, or wait and see how it goes – with a later reconstruction if you need it. This study was done, using 121 patients from two centres in Sweden, and it was published in the New England Journal of Medicine in 2010.
The study was well conducted, choosing only young (18-35) active patients with acute tears – patients that would normally be treated with reconstruction. And the analysis was very thorough, looking at the results a few different ways. This can be tricky (intention to treat, as-treated analyses etc.), but when all the different analyses come up with the same answer, it can be reassuring.
The results at two years showed similar functional outcomes between the two treatments. Importantly, the results were also similar between the non-operative group that had a late reconstruction, and the non-operative group that did not.
What it showed is that if you do not have a reconstruction straight away, most of the time (61% in this case) you will not need one, and will function just as well as if you had a reconstruction.
There are still many arguments put forward for performing an early reconstruction. Often patients require surgery for meniscus tears; why not do a reconstruction at the same time anyway? A reconstruction might reduce the incidence of later meniscal tears. And of course: “but if I don’t do it for them, the surgeon next door will do it instead”. The first two arguments have not been supported by the pragmatic comparative studies to date. The last argument is a business argument, more relevant to the surgeon than the patient.
The bottom line
The chance of eventually needing a knee reconstruction after sustaining a torn ACL is still fairly high. There may be some reasonable arguments for having an early reconstruction (time, for example). However, patients will function just as well, and have symptoms to a similar degree if they opt to leave it alone and only have a reconstruction later if necessary, and most will avoid a reconstruction.
The shame is that there are about a million ACL reconstructions performed each year in the world, and there has only been one randomised trial performed comparing it to non-operative treatment. That seems like a lot of operating and not much evidence gathering.