Hypermobility of the first ray in patients with planovalgus feet and tarsometatarsal osteoarthritis

BackgroundHypermobility in the foot is a common observation but difficult to quantify. Primary tarsometatarsal arthritis is less common and its aetiology uncertain. This study introduces a novel means of clinical measurement for range of motion of the medial column and investigates the association between hypermobility, planovalgus foot shape and tarsometatarsal arthritis.Method32 planovalgus feet with symptomatic tarsometatarsal arthritis were compared with 36 controls. Radiographic angular measurements and arthritic grade were recorded from standing radiographs. Medial column flexion and extension was measured clinically using a validated electronic goniometer.ResultsThere was a significant difference in medial column range of motion between the patient and control groups (17 ± 5° compared to 9 ± 3° [P < 0.001]).ConclusionPatients with planovalgus feet and tarsometatarsal osteoarthritis have greater range of motion of the medial column than controls with normal feet when measured using this technique. Recognition of this association may lead to progress in prevention and treatment.