Relationship Between Magnetic Resonance Imaging Features and Knee Pain Over Six Years in Knees Without Radiographic Osteoarthritis at Baseline.

OBJECTIVE

To explore whether magnetic resonance imaging (MRI) features suggestive of knee osteoarthritis (OA) are associated with presence of knee pain in possible early-stage OA development.

METHODS

We included 294 participants from the Osteoarthritis Initiative (mean ± SD age 50 ± 3 years; 50% women) with baseline Kellgren/Lawrence grade of 0 in both knees, all of whom had received knee MRIs at 4 different time points over 6 years (baseline, 24, 48, and 72 months). Using a linear mixed model (knees matched within individuals), we studied whether MRI features (meniscal body extrusion [in mm], cartilage area loss [score 0-39], cartilage full thickness loss [range 0-16], osteophytes [range 0-29], meniscal integrity [range 0-10], bone marrow lesions [BMLs] including bone marrow cysts [range 0-20], Hoffa- or effusion-synovitis [absent/present], and popliteal cysts [absent/present]) were associated with knee-specific pain as reported on the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire using a 0-100 scale (worst to best).

RESULTS

The differences in KOOS knee pain score for a knee with a 1 unit higher score on MRI were the following: meniscal extrusion -1.52 (95% confidence interval [95% CI] -2.35, -0.69); cartilage area loss -0.23 (95% CI -0.48, 0.02); cartilage full thickness loss -1.04 (95% CI -1.58, -0.50); osteophytes -0.32 (95% CI -0.61, -0.03); meniscal integrity -0.28 (95% CI -0.58, 0.02); BMLs including potential cysts -0.19 (95% CI -0.55, 0.16); synovitis 0.23 (95% CI -1.14, 1.60); and popliteal cysts 0.86 (95% CI -0.56, 2.29).

CONCLUSION

Meniscal extrusion, full thickness cartilage loss, and osteophytes are associated with having more knee pain. Although these features may be relevant targets for future trials, the clinical relevance of our findings is unclear because no feature was associated with a clinically important difference in knee pain.