Arthrodesis or arthroplasty for end stage hallux rigidus: A comparison of 3D kinematic and plantar pressure gait metrics and PROMs.

BACKGROUND: In end stage hallux rigidus, treatment is mainly surgical in the form of joint arthrodesis or arthroplasty. Although promising results have been reported for both surgical techniques a detailed comparison of gait biomechanics has not been conducted. RESEARCH QUESTION: How do post-operative 3D kinematics, plantar pressures and patient reported outcome measures (PROMs) differ following arthrodesis or arthroplasty for end-stage hallux rigidus? METHODS: Eleven arthrodesis and eleven arthroplasties were performed. Pre- and post-operative (follow-up time, 7.5 ± 1.0 months) data were collected using a BTS motion capture system, BTS force plates and RS Footscan pedobarographic pressure plates. PROMs were also assessed using the MOxFQ. Spatio-temporal and plantar pressure measures were analysed using a two-way mixed model ANOVA whilst statistical parametric mapping (SPM) was used to explore 3D kinematics of the foot and ankle. RESULTS: At the forefoot-hallux, there were significant post-arthrodesis reductions in dorsiflexion (0-11%, p = 0.028 and 82-100%, p = 0.008). Significant post-arthrodesis reductions in hindfoot-forefoot plantarflexion were also identified (87-100%, p = 0.035). Significant effects of time were identified in coronal plane kinematics, plantar pressures, spatio-temporal results (stride length, step length and velocity) and MOxFQ. SIGNIFICANCE: The lack of 1st MTPJ dorsiflexion following arthrodesis and reduced hindfoot-forefoot plantarflexion disrupted the medial longitudinal arch and compromised normal function of the distal foot. However, both surgical techniques statistically improved spatio-temporal parameters, coronal plane kinematics and medialisation of load. These improvements were likely the result of reduced pain and demonstrate that both surgical interventions are beneficial to patients.