Associations between MRI features and pain in first metatarsophalangeal joint osteoarthritis

Objectives First metatarsophalangeal (MTP) joint osteoarthritis (OA) is a common and disabling foot condition, but the relationship between localised joint changes with pain severity is poorly understood. This study aimed to investigate the association between joint changes on magnetic resonance imaging (MRI) with pain severity in individuals with first MTP joint OA. Methods This cross-sectional study used baseline data from 80 participants aged 36 to 74 years (mean [SD] = 57.5 [8.8]) with first MTP joint OA enrolled in two randomised trials. MRI atlas features assessed included osteophytes, bone marrow lesions, bone cysts, effusion-synovitis, cartilage loss, and joint space narrowing. Pain severity was measured using a visual analogue scale. Regression analyses included linear, multivariable models, with exploratory stepwise forward-selection analyses to identify MRI features associated with pain severity. Results Osteophytes, joint space narrowing, bone marrow lesions in the proximal phalanx and sesamoids, cysts, and effusion-synovitis were not associated with pain severity in unadjusted or adjusted analyses. In contrast, first metatarsal head bone marrow lesions (involving >66% of the first metatarsal head) were significantly associated with pain severity in adjusted (p = 0.025) and subsequent stepwise analyses (p = 0.039). Cartilage loss was additionally associated with pain severity in the stepwise analysis (p = 0.047). Conclusion MRI-detected bone marrow lesions in the first metatarsal head and cartilage loss are associated with pain severity in first MTP joint OA. These findings provide insights into local mechanisms contributing to pain severity in the first MTP joint OA and may support the development of targeted interventions. Further research is needed to clarify the temporal relationship between MRI-detected pathology and symptoms.