Exercise after ACL surgery may protect knees from early osteoarthritis

Recovery from ACL surgery is often more difficult than expected. About half of patients are still dissatisfied with their knee health two years after the procedure. Even more concerning, roughly half develop signs of early-onset knee osteoarthritis within a decade, often before reaching age 40.

Medical guidelines recommend combining exercise rehabilitation with patient education after ACL surgery, yet many people receive treatment that falls short of these recommendations. One obstacle is the widespread concern, shared by some patients and healthcare professionals, that exercise could damage already vulnerable knee cartilage.

A New Approach to Recovery After ACL Surgery

To investigate whether additional rehabilitation could help, researchers at La Trobe University's Sport and Exercise Medicine Research Centre conducted the SUPER-Knee clinical trial. It was the first study to evaluate the benefits of combining exercise therapy and education more than nine months after ACL reconstruction, a time when patients are generally expected to have recovered even though many continue to experience problems.

The researchers enrolled 184 adults between the ages of 18 and 40 who were still struggling with knee symptoms one to three years after their operations. Participants were assigned to either a progressive exercise therapy program or a comparison group that received a single educational session.

The findings, published in Annals of Internal Medicine, showed that participants who completed the four-month program under the guidance of a physical therapist experienced improvements in knee health and muscle strength, along with less pain and better quality of life.

Importantly, these benefits came without evidence that the exercises were damaging knee cartilage or worsening early osteoarthritis. The results challenge the belief that physical activity necessarily makes injured knees worse.

Exercise Offers Hope Against Early Knee Osteoarthritis

Associate Professor Adam Culvenor, who led the research, said the findings provide much-needed evidence about how to help younger patients who remain at risk of knee osteoarthritis following ACL surgery.

"Currently we don't have any high-quality evidence for what treatments should be offered to young people at risk of early-onset knee osteoarthritis. Our SUPER-Knee study changes this, and addresses a globally recognized research priority," Associate Professor Culvenor said.

"Our study showed physiotherapist-supervised exercise therapy and education is safe and should be recommended to improve the knee health of young people at high risk of early-onset osteoarthritis following ACL reconstruction.

"The evidence generated by the SUPER-Knee trial can be used to update international clinical practice guidelines for rehabilitation following ACL reconstruction and could be a lifeline for young people struggling after serious knee injuries.

"The intervention is ready to be used by local health professionals with minimal specialized equipment or staff training."

The findings could influence how clinicians approach rehabilitation long after ACL surgery, particularly for patients whose symptoms continue beyond the usual recovery period. Although the trial did not establish whether the program prevents osteoarthritis over the long term, it demonstrated that supervised exercise can improve knee health without accelerating the cartilage damage or early osteoarthritis researchers were monitoring.

Years of Knee Pain After a Serious Sports Injury

For Ruby Cumming, the challenges of recovering from ACL surgery were deeply personal. In 2019, when she was 24, she tore her ACL while playing Australian rules football. Hoping to return to the sport as quickly as possible, she underwent reconstructive surgery within six weeks.

But the operation did not lead to the recovery she had imagined. Her rehabilitation continued for years, and she ultimately decided not to return to football.

"I thought if I had the surgery and did the rehab I'd be able to get back to normal. After surgery impacted my entire life - not just footy - I changed my outlook and decided I wanted to avoid re-injuring my knee ever again so haven't played contact sport since," Ruby said.

"Experiencing regular pain, not being able to walk, getting public transport to work and living independently all became really challenging for me."

Cumming remained committed to her rehabilitation, regularly attending physical therapy appointments and performing prescribed exercises. She initially exercised daily before moving to a weekly routine. Despite those efforts, she continued to experience varying degrees of knee pain every day for three to four years.

Her experience changed after she enrolled in the SUPER-Knee trial and began participating in weekly rehabilitation sessions supervised by a physical therapist.

"When I joined the SUPER-Knee program and did weekly physio-supervised rehab, this improved my pain significantly," Ruby said.

The research suggests that people who continue to struggle after ACL reconstruction may benefit from additional structured rehabilitation, even years after their original injury. Because the program requires little specialized equipment or additional staff training, researchers say healthcare professionals could readily incorporate it into existing treatment services.

The SUPER-Knee clinical trial received funding through a Project Grant from Australia's National Health and Medical Research Council (NHMRC).