DO PATIENTS WITH PLANOVALGUS FEET AND MIDFOOT ARTHRITIS HAVE HYPERMOBILITY OF THE FIRST RAY?

Abstract

Introduction: Hypermobility is a common finding, however, it lacks diagnostic parameters and is poorly understood, especially in the foot.

Aim: To quantify medial column/first ray mobility in patients with midfoot arthritis and planovalgus feet.

Methods: We compared first ray mobility in patients with radiologically defined midfoot tarsometatarsal osteoarthritis, a radiologically normal first ray and planovalgus feet, with control subjects who had normal feet and first rays. An all female group of 20 patients (mean age of 70) and 20 controls (mean age of 53) met the criteria. Analysis of patients’ x-rays identified the site of their arthritis and allowed angular measurements of their flat foot deformity. Patient and control subjects underwent identical examinations, recording hindfoot correctability, medial longitudinal arch appearance, hindfoot prontion and supination, forefoot supination and degrees of flexion/extension and abduction/adduction with an electronic goniometer. Each subject was graded by the AOFAS and SF-36 outcome scores.

Results: There was a significant difference in first ray mobility between the patient and control subjects for all positions adopted (P=< 0.001), except when dorsiflexed and weight bearing (P=0.052). Patients with a neutral non-weight bearing ankle exhibited greatest mobility of 16.8 +/− 4.7 degrees compared to 9.4 +/− 2.6 degrees in controls. This was a significant difference, P=< 0.001, as was the difference between patients adopting the NWB plantarflexed, dorsiflexed and WB neutral positions. P=0.002, P=0.014, P=0.001 respectively. Patients’ median score for 5 out of 8 SF36 domains were considerably less than controls, as were patients’ AOFAS. Reduced physical and social functioning were shown to be linked to poor foot scores.

Conclusion: Patients with planovalgus feet and tarsometatarsal OA have greater first ray mobility than controls with normal feet. Recognising this may help plan orthotic or surgical treatment.