Can an ACL Injury Lead to Arthritis in the Future?

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The short answer is yes. Read this blog to find out how and what you can do to reduce your chances of arthritis.

Arthritis as a result of an ACL injury is often termed post-traumatic osteoarthritis (PTOA). PTOA accounts for 12% of all cases of osteoarthritis.^[6] Osteoarthritis can occur as a result of injury or natural wear and tear of a joint. Our blog - What is Osteoarthritis - gives a great summary on this topic and explains exactly what arthritis is.

People with ACL injuries have been found to have a higher risk of later developing PTOA, where around 50-90% of ACL injuries progress to PTOA.^[2] There are a number of factors that are believed to contribute to the development of PTOA, however it’s important to note that the actual process is not yet fully understood.

Before Surgery

After an injury, a number of biological processes take place in the body to try to heal itself. Some of the products of these processes that take place after a knee injury are thought to harm parts of the knee joint, and contribute to the development of OA.^[1]

Structural factors

Higher incidences of PTOA were found in patients who had damage to certain structures in the knee joint other than the ACL.^[1] These structures include the articular cartilage (covers the ends of your knee bones and makes it easier to bend your knees), meniscus (a soft cushion between your two bones that prevents them from rubbing together), and subchondral bone (the part of the bone that touches the cartilage).^[1] Damage to these structures can cause both biological and structural changes in the knee that can lead to PTOA.^[1]

Neuromuscular factors

The role of the ACL in the knee is to prevent it from moving around too much, but it also contains things called mechanoreceptors that sense things like movement and stretch.^[1] Mechanoreceptors tell the brain what the knee is doing - so that in turn the brain can control the muscles that move the knee. An ACL injury cuts this connection and loses control over these muscles, and causes them to become weaker over time.^[4] Quadriceps , which are responsible for straightening your knees, are an example of such muscles. Studies show that having weaker quadriceps are linked to a higher incidence of knee osteoarthritis.^[3] This may be because quadriceps are important for absorbing shock when you step down on your leg, so when they are weaker there is more stress on your knee joint than normal. This excess stress on the knees can be a contributing factor to development of PTOA.^[1]

Mechanical factors

An ACL injury can result in a change in the way that people walk and shift weight onto their injured knee. This change occurs because people are in pain when they load the injured side or because they are concerned about re-injury. These two factors can drastically change how a person walks and loads their injured side.^[5] In the long run this can change the amount and location of the pressure on the cartilage around the knee joint leading to damage, and ultimately increasing the chances of developing PTOA.^[1]

Additional factors

Things like gender, age, obesity, physical activity level, body mass index level, smoking, and time between the injury and surgery can all also affect the risk of developing PTOA after an ACL injury.^[7]

PTOA is a progressive and chronic disease, and in the late stages of the disease, changes are irreversible and may require surgery, such as a knee replacement surgery .^[7] For more information about how a knee replacement may cure arthritis check out this blog! That being said, PTOA should be addressed as early as possible to delay the progression of the disease.

Of the factors discussed, the ones that can be controlled and actively treated are neuromuscular and mechanical factors. An appropriate rehabilitation plan should include ways to improve neuromuscular control, strength, power, and muscle symmetry.^[7] Working on these aspects can affect the way that weight is distributed on the knees and eliminate factors that contribute to the development of PTOA.

Conclusion

Yes, ACL injuries have been linked to a higher incidence of post traumatic osteoarthritis. While the exact cause of this isn’t clearly known, people believe it is the result of a number of different factors that contribute to the development of osteoarthritis. These factors include biological, neuromuscular, structural, and mechanical factors. An appropriate rehabilitation plan can reduce the risk of post traumatic osteoarthritis by addressing some of these factors.

Curovate is an app created by a physical therapist to specifically address strength, neuromuscular control, power and muscle symmetry after an ACL injury or ACL surgery. Use it for your daily recovery after injury or surgery. The Curovate app is available to download, just click the link below to get your recovery started today.

If you need further customized assistance during your surgery or injury recovery check out our Virtual Physical Therapy page to book your 1-on-1 video session with a physical therapist.