A Prospective Study Evaluating Gait and Clinical Outcome Following First Metatarsophalangeal Arthrodesis for Hallux Rigidus

Background: Arthrodesis of the first metatarsophalangeal joint (MTP1) is a common intervention for hallux rigidus (HR). The procedure eliminates MTP1 motion but results in significant pain relief and high satisfaction rates, although MTP1 is eliminated. Less evidence is available regarding the effects on gait and the presence of compensatory mechanisms. The aim of this study is to investigate the effects of MTP1 arthrodesis on gait and patient-reported outcome measures (PROMs) compared with preoperative functioning and healthy individuals. Methods: In this prospective study, 10 patients (10 feet) with HR who underwent MTP1 arthrodesis were evaluated before and after surgery and compared with 15 healthy controls (30 feet). Gait analysis was performed with a motion capturing system using the multi-segment Oxford foot model. Spatiotemporal parameters and kinematics were quantitatively analyzed. PROMs were evaluated using validated questionnaires including the American Orthopedic Foot and Ankle Society Hallux Metatarsophalangeal-Interphalangeal (AOFAS-HMI) scale, the Numeric Pain Rating Scale (NPRS), and the Manchester-Oxford Foot Questionnaire (MOXFQ). Results: MTP1 joint motion was reduced in HR and further reduced after MTP1 arthrodesis compared with healthy controls. Furthermore, intersegmental ROM analysis revealed increased forefoot frontal plane motion (pronation and supination) in HR compared with healthy controls. This was also observed after MTP1 arthrodesis, while additionally increased frontal plane motion in the hindfoot (inversion and eversion) was observed compared with HR and healthy controls. PROM evaluation revealed improved AOFAS-HMI (from 55.7 to 79.1 points, p = 0.002) and NPRS (from 5.7 to 1.5 points, p = 0.004) scores after surgery. Additionally, improvements in the MOXFQ score (from 51.0 to 20.0 points, p = 0.002) were observed. Conclusions: Due to the loss of sagittal hallux motion, foot and ankle kinematics are changed in HR patients and after MTP1 arthrodesis compared with healthy controls. Loss of MTP1 motion results in increased frontal plane motion of the forefoot in HR, and increased frontal plane motion of the fore- and hindfoot after MTP1 arthrodesis. Additionally, substantial improvements in PROMs were recorded after surgery.