OA 15 Years After ACL Tear

Anterior cruciate ligament (ACL) deficiency is a well-recognized risk factor for the development of knee osteoarthritis (OA). Studies have shown that a torn ACL leads to OA in more than half of affected knees five to 15 years after injury. This type of injury is often accompanied by meniscal tears. Removal of damaged menisci also is a known strong risk factor for knee OA. During ACL reconstruction, surgeons generally will try to repair any accompanying meniscal tear or clean out torn pieces of meniscal tissue, whereas the patient or surgeon may not opt for surgery solely to repair or remove a torn meniscus.

What Problem Was Studied?

 

Anatomy Basics

Anterior cruciate ligament: One of four major ligaments of the knee. It is one of the most commonly injured knee ligaments.

Meniscus: C-shaped cartilage-like tissues located between the bones of the knee. They help the knee to function properly by bearing load, absorbing shock, stabilizing the joint and providing lubrication.
About half of people who suffer an ACL tear opt to have it surgically reconstructed. Studies have shown, however, that although ACL reconstruction does stabilize the knee, it does not seem to decrease the risk of developing OA. A team of physicians from Lund University in Sweden and Boston University School of Medicine, including Arthritis Foundation-funded scientist Martin Englund, MD, PhD, hypothesized that people with ACL tears could achieve good function and avoid OA development through a program of rehabilitation and activity modification instead of ACL reconstruction.

To test this hypothesis, the team designed a study to determine the prevalence of knee OA, meniscal injuries and meniscus removals as well as knee function and symptoms in people with ACL injuries treated without primary (initial) ACL reconstruction.

What Was Done in the Study?

One hundred patients with an acute ACL injury were recruited from Lund University Hospital between 1985 and 1989. All patients were recommended not to have their ACL surgically reconstructed, but to undergo a period of physical therapy and to modify their physical activities. The participants had their injuries verified by arthroscopy shortly after the injury and then they started eight weeks of physical therapy to regain joint mobility and improve neuromuscular function so the muscles in the leg could compensate for the deficient ACL, providing stability. After 15 years, the participants were contacted again and invited to participate in a follow-up exam.

What Were the Study Results?

Of the 100 study participants, 60 had a meniscal tear along with their ACL injury; of those 60, 25 patients had to have parts of their meniscus removed at the time of injury. An additional 21 meniscectomies were performed during the subsequent years. At some point over the 15-year timeframe, 22 participants ended up having their ACL reconstructed due to frequent knee buckling.

Of the 100 people who were originally enrolled, 79 consented to knee X-rays in the re-evaluation 15 years later. Radiographic OA had developed in only 13 of 79 knees. All these 13 OA cases had undergone meniscectomy at some point since the ACL injury. OA was present in 6 of 17 reconstructed knees (17 of the 22 who had ACL reconstruction had X-rays taken) and 7 of 62 nonreconstructed knees (62 of 78 who did not have ACL reconstruction had X-rays taken).

Those participants with intact menisci and nonreconstructed knees achieved the best scores for pain, symptoms, activities, recreation and quality of life. Before their ACL injury, participants had an average Tegner physical activity score of 7; this score decreased to an average of 4 after 15 years. Those with a reconstructed knee had an average score of 4.5, whereas those who did not have the ACL reconstructed had an average score of 3.7.

What Does This Mean for People With an ACL Tear?

The nonoperative treatment employed in this study provided a good outcome regarding knee OA, knee function and need for reconstruction in patients willing to modify their activity level not to involve sports with high risk for reinjury.

The study authors conclude, “Our study thus clearly confirms that in the ACL-injured knee, reconstructed or not, a meniscectomy is a potent risk factor for OA. Preservation of the meniscus seems beneficial irrespective of whether an ACL reconstruction was performed. In patients with ACL injury willing to moderate their activity level, initial treatment without ACL reconstruction should be considered.”

An upcoming report of these ACL injured patients looks at the prevalence of OA around the knee cap and its relevance for knee symptoms and knee function. This joint is often overlooked in studies of knee OA development.

Because we know that removal of the meniscus (or parts of it) leads to a high risk of early knee OA, it is conceivable that surgical repair of meniscal tears, restoring meniscal function, may lower this risk. The challenge, however, is that repair is not always possible. Furthermore, repair is associated with a long rehabilitation (healing is slow) and the treatment is still not proven to reduce the risk of OA. Dr. Englund says, “It appears that leaving small meniscal tears, judged not to cause mechanical interference, in place is a better alternative than extensive removal of meniscal tissue.”

Neuman P, Englund M, Kostogiannis I, et al. Prevalence of tibiofemoral osteoarthtitis 15 years after nonoperative treatment of anterior cruciate ligament injury. Am J Sports Med. Epub ahead of print May 15, 2008.

For more information on knee surgery, read 10 Ways to Postpone or Avoid Knee Surgery

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