A prospective clinical and biomechanical analysis of feet following first metatarsophalangeal joint replacement

Background: There is a lack of research providing a biomechanical outcome following 1st MTPJ replacement for hallux rigidus. Despite this, 1st MTPJ replacement continues to be an alternative surgical option to fusion for this painful debilitating condition. Several studies do consider the patient reported outcomes which are subjective. Research Question: The objective of this study is to provide an in depth biomechanical analysis to examine the effects of 1st MTPJ replacement for hallux rigidus on gait mechanics. Methods: Kinematic data was collected at our CMAS (Clinical Movement Analysis Society) UK accredited gait laboratory during the gait cycle together with pressure plate pressure readings and a validated patient outcome measure before surgery and at 6 and 12 months after surgery. A complete literature review is performed. Results: Kinematic data revealed a significant increase in stride length, cadence and velocity following 1st MTPJ replacement for hallux rigidus. Foot kinematic data revealed significantly reduced tibia-hindfoot abduction and pronation and reduced hindfoot-forefoot supination and adduction. There was no effect on 1st MTPJ weight bearing range of motion. Pressure plate data revealed an increase in peak pressure and pressure time integral towards the 1st metatarsal following surgery. There was a significant improvement in the patient reported outcome measure. Significance: This study has demonstrated objectively that following 1st MTPJ replacement, biomechanically, a restoration of the foot posture to allow medialisation of foot pressures towards the medial column and normalisation of gait including an increase in the stride length, cadence and velocity and that clinically, there was an improvement in the MOXFQ.