First metatarsophalangeal joint range of motion is associated with lower limb kinematics in individuals with first metatarsophalangeal joint osteoarthritis

Background: Osteoarthritis of the first metatarsophalangeal joint (1st MTP joint OA) is a common and disabling condition that results in pain and limited joint range of motion. There is inconsistent evidence regarding the relationship between clinical measurement of 1st MTP joint maximum dorsiflexion and dynamic function of the joint during level walking. Therefore, the aim of this study was to examine the association between passive non-weightbearing (NWB) 1st MTP joint maximum dorsiflexion and sagittal plane kinematics in individuals with radiographically confirmed 1st MTP joint OA. Methods: Forty-eight individuals with radiographically confirmed 1st MTP joint OA (24 males and 24 females; mean age 57.8 years, standard deviation 10.5) underwent clinical measurement of passive NWB 1st MTP joint maximum dorsiflexion and gait analysis during level walking using a 10-camera infrared Vicon motion analysis system. Sagittal plane kinematics of the 1st MTP, ankle, knee, and hip joints were calculated. Associations between passive NWB 1st MTP joint maximum dorsiflexion and kinematic variables were explored using Pearson's r correlation coefficients. Results: Passive NWB 1st MTP joint maximum dorsiflexion was significantly associated with maximum 1st MTPJ dorsiflexion (r = 0.486, p < 0.001), ankle joint maximum plantarflexion (r = 0.383, p = 0.007), and ankle joint excursion (r = 0.399, p = 0.005) during gait. There were no significant associations between passive NWB 1st MTP joint maximum dorsiflexion and sagittal plane kinematics of the knee or hip joints. Conclusions: These findings suggest that clinical measurement of 1st MTP joint maximum dorsiflexion provides useful insights into the dynamic function of the foot and ankle during the propulsive phase of gait in this population.