Is it time for knee surgeons to reconsider ACL reconstruction? Alex Dodds, knee consultant for the Cotswolds, Cheltenham and Gloucester, thinks not.
*photo courtesy of wavebreakmedia via shutterstock
Over the past year, a huge amount has been published about ACL tears. Take this piece from The Washington Post which captures the mood of virtually every piece since with its headline: “A torn ACL can heal itself, new study shows. Surgeons disagree.”
That’s not quite true. It’s all a question of degree, but when it comes to the most severe tears, yes, surgeons do disagree.
What does the ACL do?
Let’s rewind a little. The ACL (anterior cruciate ligament) is one of several ligaments in the knee joint. It crosses the middle of the knee (hence ‘cruciate’) connecting the thighbone and shinbone. Its job is to stabilise the knee and keep bones in their place. Imagine this: with your foot firmly planted on the floor, you twist to the left or right. There’s a limit to how far you can twist, and the ACL is in large part responsible for ensuring you can’t overdo it.
When you rupture your ACL, you’re likely to feel a sense of instability, as though your knee is about to give way, particularly when you twist. That’s the effect of the ACL not working properly (or at all).
There are degrees of ACL tear. A Grade 1 tear is the least severe, and generally means you’ve stretched your ACL rather than torn it completely. A Grade 3 tear is the most severe and indicates that your ACL is torn through and in two bits.
How do you treat ACL tears?
Traditionally, severe ACL tears are treated through reconstruction. That’s not repair, because repair involves attaching the two torn parts of the ligament back together again and that has a complicated and not entirely successful track record.
Reconstruction involves taking a graft from another ligament (often a hamstring) and using it as a sort of scaffold over which new ligament can grow. ACL reconstruction is the gold standard of treatment, although there’s no denying recovery takes a long time and success is not guaranteed, especially if you’re someone who wants to return to elite sport.
> Discover more about anterior cruciate ligaments
> Discover more about anterior cruciate ligament reconstruction
Can the ACL heal itself?
The question is, is there a reliable alternative to ACL reconstruction? In 2022, a paper was published suggesting there might be. By analysing the MRI scans of 120 ACL tear patients, researchers found “evidence of [spontaneous] healing” in one in three patients.
Cue lots of publications picking the story up since and using it to ask why we’re persisting with ACL reconstruction procedures when the ligament can heal itself.
So let’s unpack those findings a little.
MRI isn’t the whole story: The study was built on evidence presented by MRI scans. The issue here is that an MRI scan is just one part of the diagnostic process. More important than how the ligament looks is that the patient feels the knee is stable. This most crucial aspect of the process is missing from the study.
“Evidence of healing”: That wording carries a lot of weight. Evidence of healing isn’t the same as saying ‘healed’.
Bracing issues: The results in this study were achieved using a particular type of cross-bracing that requires the knee to be flexed at 90 degrees before being straightened, which can lead to problems of its own in terms of joint stiffness.
The ACL lottery: The study found evidence of spontaneous healing in one in three patients. Yet the patient cohort comprised all three grades of ACL tear. With appropriate bracing and physio, we might have expected healing in a number of these patients, and low grade sprains would probably not have been candidates for surgery anyway.
Additionally, you only know which patients’ ACLs have successfully healed in retrospect. Patients who will still need ACL surgery will have that surgery delayed while they go through the bracing process.
The evidence: I was on a surgeons’ course in Sheffield recently where the ACL issue came up. The consensus was that we currently lack good, clear, randomised clinical evidence. The results of this study remain effectively anecdotal. It’s not surprising patients and the press have seized on it – the story is an exciting one.
But there are a lot of blanks to fill in before we consider changing the way we approach ACL reconstruction.
If your knee feels unstable, please book an appointment at my knee clinic in Cheltenham or call 01242 246549
> Discover more about anterior cruciate ligaments
> Discover more about anterior cruciate ligament reconstruction