Association between clinical and MRI-detected imaging findings for people with midfoot pain, a cross-sectional study.

Background: Midfoot pain is common but poorly understood, with radiographs often indicating no anomalies. This study aimed to describe bone, joint and soft tissue changes and to explore associations between MRI-detected abnormalities and clinical symptoms (pain and disability) in a group of adults with midfoot pain, but who were radiographically negative for osteoarthritis.

Methods: Community-based participants with midfoot pain underwent an MRI scan of one foot and scored semi-quantitatively using the Foot OsteoArthritis MRI Score (FOAMRIS). Foot pain and disability were recorded using visual analog scales (VAS) and the Modified-Manchester Foot Pain Disability Index (MMFPDI). Associations were assessed for continuous data using Spearman's Rho, and for categorical data, a Wilcoxon signed rank test. Linear regression was used to explore the association between participant-reported measures and MRI abnormalities, adjusted for age, sex and BMI.

Results: Sixty-one participants (70% female, mean age 48.5 years, median BMI 28.6 kg/m) were included. Median VAS pain was 31/100 mm (IQR 21-47) and median disability was 30/48 (IQR 26-36). There was a moderate association between midfoot pain severity and the number of joints exhibiting joint space narrowing; adjusted results suggested 31% (95% confidence interval 3%-68%) worse VAS pain with each additional affected joint. Greater numbers of joints with cysts were associated with worse VAS pain [14% (0%-31%)] and disability [1.1 units (0-2.2)]. Effusion/synovitis was associated with MMFPDI pain. No other MRI abnormalities were associated with sex, body mass and foot pain/disability measures. Bone marrow lesions, joint space narrowing, cysts and osteophytes occurred more frequently with age. MRI abnormalities were common, particularly in the talo-navicular joint, first and second cuneo-metatarsal joints. Those with dorsal foot pain had more multi-joint involvement, bone marrow lesions, joint space narrowing and cysts and for those with pain on midfoot movement, bone marrow lesions and cysts were reported.

Conclusions: In people with midfoot pain, MRI-detected features of osteoarthritis and soft-tissue abnormalities were found, clustered in the medial and intermediate cuneiform joints. These features were more common with age but not associated with pain or disability measures. Younger people with dorsal midfoot pain exhibited early signs of bone and joint features of osteoarthritis and we recommend further imaging studies to determine the clinical and diagnostic significance.