REVEALING THE HIDDEN CULPRIT: CONTRALATERAL KNEE'S ROLE IN OSTEOARTHRITIS DISEASE ACTIVITY: DATA FROM THE OSTEOARTHRITIS INITIATIVE

Abstract

INTRODUCTION

An impediment to our current treatment strategies and clinical trials for people with knee OA is focusing only on one knee, often ignoring the contralateral knee. Failing to address the contralateral knee may explain why many localized therapeutic approaches fail to achieve optimal results.

OBJECTIVE

We explored whether an MRI-based composite score of BM lesion and effusion-synovitis volumes related to contralateral knee OA disease severity.

METHODS

Using data from the OAI, we conducted cross-sectional knee-based analyses among participants with bilateral knee MRIs and at least one knee with KLG ≥1 and a WOMAC pain score ≥10/100 (n=693). We included 1,386 knees from participants with an average age of 62 (SD=9) years. Most participants were overweight and had mild-to-moderate radiographic OA. MR images were collected at each OAI site using Siemens 3.0 Tesla Trio MR systems and knee coils. Acquisitions included a sagittal IM fat-suppressed sequence (field of view=160mm, slice thickness=3mm, skip=0mm, flip angle=180 degrees, echo time=30ms, recovery time=3200ms, 313 × 448 matrix, x-resolution=0.357mm, y-resolution=0.357mm), which was used to measure BML and effusion-synovitis volumes. BM lesion and effusion-synovitis volumes on MRIs were used to calculate a composite score (“disease activity”). A disease activity score of 0 approximated the average score for a reference sample (n=2,787, 50% had radiographic knee OA, average [SD] WOMAC pain score = 2.8 [3.3]); lower scores (negative scores) indicate milder disease, while greater values indicate worse disease. We divided the disease activity score into tertiles. We used four separate multinomial logistic models to explore the association between disease activity in knees with and without radiographic OA (outcome) and the contralateral disease severity (KLG or disease activity; exposure).

RESULTS

Disease activity among knees without radiographic OA had statistically significant relationships with contralateral disease activity (range of odds ratios: 4.86-23.22) but not contralateral KLG (range of odds ratios: 0.86-1.01; Table). Disease activity among knees with radiographic OA had statistically significant relationships with contralateral disease activity and KLG; however, the association was stronger for contralateral disease activity than KLG (range of odds ratios: 3.67-21.29 versus 1.96-2.20; Table).

CONCLUSION

Contralateral knee OA severity is related to disease activity. Disease activity in the contralateral knee is a more informative measure of disease severity than relying on radiographs. Future studies need to explore how the contralateral knee could impact clinical trial screening, monitoring, and intervention strategies, especially when testing localized therapies.