Bone marrow lesions, sex predict knee osteoarthritis

Knee osteoarthritis progression can be predicted by MRI findings of medial collateral ligament edema, bone marrow lesions, and being female, according to a study presented at the RSNA meeting.

Normally, x-ray images evaluate knee osteoarthritis. But the current study suggests MRI can be a valuable tool in the assessment and staging of the condition. Until now, factors related to progression of primary knee OA have been largely unknown.

Previous research suggested bone marrow lesions and female sex can predict knee OA progression. The current study validates prior models and also identified a new predictor: medial collateral ligament edema.

A retrospective cohort study of 123 patients with knee pain was chosen for inclusion in the study by querying the RIS at Loma Linda University Medical Center from 2000 to 2008. An initial knee radiograph and an MRI less than 12 months apart were included in the parameters as well as radiographic follow-up from two to nine years after the initial MRI. The researchers then categorized patients as having radiographic progression or no radiographic progression of their knee OA based on evaluations of joint space narrowing, subchondral irregularity, and development of osteophytes between initial and follow-up radiographs.

Of 123 patients in the study, 44 showed progressive knee osteoarthritis. Medial collateral ligament edema, bone marrow lesions, and the female sex were found to be independent predictors of knee osteoarthritis progression, said Dr. Peter Pham, a radiology resident at Loma Linda University in Loma Linda, CA, who presented the research.

The researchers measured the association between each MRI finding and progression score by using a chi-square analysis and calculating an odds ratio.

They found that if a patient who received an MRI today had medial collateral ligament edema, for instance, that person's risk of knee OA progression would be about double 16 months from today.

“If patients have two or three risk factors, they are at high risk for progressive knee osteoarthritis and a clinician can plan accordingly,” said coauthor Dr. J. Paul Jacobson, an assistant professor of radiology at Loma Linda University.

For instance, physicians can determine which patients will most likely need knee replacement surgery and which patients will benefit from just careful monitoring.

“This model predicts who is going to get worse more quickly; it can advise the patient what's in store for them,” Jacobson said.

The MR images were also analyzed for meniscal tear, meniscal subluxation, chondromalacia, bone marrow edema, subchondral cysts, joint effusion, and synovial thickening, but none of those predicted knee OA progression as well as medial collateral ligament edema, bone marrow lesions, and female sex.

The researchers are submitting the findings for publication in Radiology.