Study debunks longstanding medical myth that a torn ACL can't heal

Danyelle Anderson says her “world came crashing down” when she tore her ACL.  (ABC News: Adam Griffiths)

Personal trainer Danyelle Anderson ruptured the anterior cruciate ligament (ACL) in her right knee during a kickboxing class.

“My whole world came crashing down, pretty much,” she said.

She was told by an orthopaedic surgeon that it wasn’t possible for her ACL to heal and that a surgical reconstruction was needed.

Reluctant to have an operation, she decided to see if her knee would improve with physiotherapy.

Three months later, a follow-up MRI showed her injury had gone from a grade three complete rupture, where the ligament is torn completely in half, to a less severe grade one tear, where some of the fibres are continuous.

“So basically, my ACL has reattached and is healing,” she said.

Ms Anderson’s story comes as no surprise to University of Melbourne researcher Associate Professor Stephanie Filbay.

In a study that has garnered worldwide attention, she re-analysed the results of a Swedish trial involving 120 patients, comparing the MRIs of those who had surgery with others who underwent rehabilitation without surgery.

“What we found, surprisingly, was that two years after injury, in those who’d had rehabilitation only, 53 per cent had signs of healing on MRI,” Dr Filbay said.

“Even more surprising was that those with signs of healing reported better outcomes than those who’d had ACL surgery.”

Evidence of healing was taken to be the presence of continuous ACL fibres where previous MRIs showed a complete disconnect in the rupture zone, as well as the ligament becoming thicker and tauter and taking on a more normal appearance.

The findings have become a hot topic in medical circles, raising questions about whether changes are needed to the way doctors treat ACL injuries.

“Everyone’s heard of incidents where someone’s on a waitlist for surgery with a torn ACL and they get opened up by the surgeon and then the surgeon says ‘well, the ACL is healed’,” Dr Filbay said.

“People thought they were extremely rare, and what the research is suggesting is that this occurs more commonly than we thought.”

Challenging accepted medical wisdom

Some surgeons have reacted to the study with scepticism, pointing to the small number of young, physically fit adult patients involved in the trial, and the difficulties of assessing healing on an MRI.

The ACL is a rope-like band of tissue that runs through the middle of the knee, connecting the thigh bone to the shin bone and playing a vital role in keeping the joint stable.

For decades, the accepted medical wisdom has been that the ACL can’t heal because of poor blood supply inside the knee joint.

“It has been a myth that the ACL never heals, something that’s been set in stone,” specialist orthopaedic knee surgeon Justin Roe said.

In practice, he said, doctors have observed that ACLs heal in some cases, but not in others.

“And that’s the holy grail — predicting who it does heal in and who it doesn’t,” Dr Roe said.

Surgical reconstruction has been viewed as the gold standard treatment, offering a more predictable outcome.

“We have good surgical techniques that have developed over the years, so we can say with confidence to patients that with a successful ACL reconstruction, they can get back to sport 70 to 80 per cent of the time,” Dr Roe said.

Dr Filbay said her research showed that patients treated non-surgically returned to sport at similar rates.

“If you’re told by your surgeon or your physio that if you ever want to play sport again, you need surgery, then it really does take away your ability to make an informed decision, because you’re going to choose surgery and you’re not accurately understanding the pros and cons of each,” she said.

“I think the best evidence at the moment shows that rehabilitation on average is just as good a treatment as surgery, but that hasn’t translated into current practice in Australia.”

Australia has one of the highest per capita rates of ACL surgery in the world.

Around 90 per cent of patients who rupture their ACL undergo an operation, costing around $10,000 a time.

The surgery involves removing the damaged ligament and replacing it with a graft of tissue taken from the patient’s hamstring or patellar (kneecap) tendon, or, in some cases, with tissue from a donor.

“If you watch the AFL or the rugby and someone tears their ACL and the commentator says they’ll be in for surgery the next day to fix their ACL, that really filters down to society and to the public,” Associate Professor Filbay said.

“If they injure their ACL, they think if Sam Kerr is having a reconstruction, that must be the best treatment for me.

“But that’s not what the evidence shows.”

Every year around 20,000 ACL reconstructions are carried out — and that figure is on the rise, particularly among females and children, with patients as young as nine undergoing surgery.

The finding that the ACL may have a greater ability to heal than previously thought has raised questions about whether all these surgeries are necessary.

“Certainly for a long time, we have known that we’ve been doing too many,” Dr Roe said.

But he said in some cases there was a danger that by not operating, the patient was at risk of doing more damage to their knee.

“What I’m concerned about is the extremism [of] going too far the other way,” Dr Roe said.

Orthopaedic knee surgeon Christopher Vertullo said the latest research has shown that around half of ACL patients are no better off having surgery.

“It is concerning that there are too many ACL injuries and too many ACL surgeries,” he said.

“There’s now lots of studies suggesting that non-surgical management of ACL injuries does very well and [that] for a high proportion of patients, upwards of 50 per cent, they’ll do just as well without an operation.”

But he said not all patients were open to trying a non-surgical approach.

“There is a mentality that people really want to be fixed and they want it now, and that is hard as a surgeon.”

He said Stephanie Filbay’s research had contributed to a robust debate on the treatment of ACL injuries, but cautioned that MRIs were not a perfect tool for assessing healing or whether the ACL is intact.

“You certainly see continuous-looking ACLs on MRI and then you examine the person and they’ve got gross instability,” he said.

He said a national ACL injury registry was needed to track patients and collect more data.

“I don’t have any doubts that there’s healing ability of the ACL,” he said.

“A registry will help us then make more informed decisions for our patients and help patients make more informed decisions.”

Choosing rehabilitation versus surgery

When sports physiotherapist Clare Walsh did her training 20 years ago, she was taught that the ACL did not heal.

“What we understood was that if somebody had an ACL injury, then they needed surgery,” she said.

These days, patients are given the option of surgery with up to a year of rehabilitation or rehabilitation alone.

“Making that decision about surgery isn’t urgent, you don’t have to make that on day one,” she said.

“Surgery may be the most appropriate choice, but if they want to try non-operative management in rehabilitation, then they can give that a go.”

A high percentage of the patients Ms Walsh sees choose the non-surgical route, some of them for financial reasons.

“The patients that tend to choose rehabilitation are those that don’t have private health cover because it’s a very expensive operation,” she said.

Patients still have the option of having surgery down the track if their knee proves to be unstable after a period of rehabilitation.

“We have great surgeons and the surgery outcomes are very good for a very high percentage of cases,” Ms Walsh said.

That’s an option that Dr Filbay pointed out is not available the other way round.

“Once someone undergoes reconstructive surgery, the ACL is removed, and it’s replaced by tissue from elsewhere in the body.” she said.

“So you’ll never have the ability of that natural healing again.”