SAN DIEGO – The more severe an anterior cruciate ligament injury, the more likely patients are to develop arthritis in the injured knee; structural changes might even be seen within 4 years of the trauma, a small study has shown.

In results presented at the World Congress on Osteoarthritis, patients who had had anterior cruciate ligament (ACL) reconstruction were four times more likely to have abnormal joint space narrowing by then if they also had a defect that extended more than halfway through their femoral cartilage (International Cartilage Repair Society grade III injury), a menisectomy, or both (odds ratio 4.11; 95% confidence interval 1.01-39.55, P = .05).

"These people were highly functioning; they were all athletic people. They had no symptoms of osteoarthritis," said lead investigator Timothy Tourville of the University of Vermont Center for Clinical and Translational Science in Burlington.

"Historically, most studies haven’t been able to demonstrate differences in [less than] 10 or 15 years. I think being able to pick them up at 4 years and identifying those who are at high risk for structural change is very important," rheumatologist David Hunter said in an interview.

"If, at the time of the injury, there is more substantive damage to either [the patient’s] cartilage or their meniscus, you are going to be more cautious about encouraging them to return to high physical activity and potentially redamaging their" knee, said Dr. Hunter, professor of medicine at the University of Sydney (Australia).

The 38 ACL patients in the study, about half women, were under 51 years of age and not obese. Their ACLs were reconstructed within a half-year of their injury, and none had gotten intra-articular injections. Other than their injury, they were in good health with no other joint problems. Baseline radiographs were compared with films at 3-4 years.

More than 60% (8/13) of those with grade III cartilage injuries had abnormal joint space narrowing at that point, compared with 28% (7/25) of those with no more than grade II injuries – defects extending less than halfway through their femoral cartilage – and intact menisci in both compartments.

"Abnormal" meant that the joint space difference between patients’ injured and uninjured knees fell outside the 95% confidence interval of bilateral differences measured in 32 matched controls.

The conference was sponsored by the Osteoarthritis Research Society International. Mr. Tourville and Dr. Hunter said they had no relevant financial disclosures. The National Institute of Arthritis and Musculoskeletal and Skin Diseases supported the work.