Quantification of Muscle Strength and Imbalance in Neurogenic Pes

Background: Pes cavus foot deformity in neuromuscular disease is thought to be related to an imbalance of muscu-lature around the foot and ankle. Themost common cause of neurogenic pes cavus is Charcot-Marie-Tooth (CMT) disease. The aim of this investigation was to objectively quantify muscle strength and imbalance using hand-held dynamometry in patients diagnosed with CMT and pes cavus, compared to healthy controls. Methods: Muscles responsible for inversion, eversion, plantarflexion, and dorsiflexion of the foot and ankle were measured in 55 subjects (11 CMT patients with a frank pes cavus, and 44 healthy controls with normal feet) using the Nicholas hand-held dynamometer (HHD). Test-retest reliability of the HHD procedure also was determined for each of the four muscle groups in the healthy controls. Results: Test-retest reliability of the HHD procedure was excellent (ICC3,1 = 0.88 to 0.95) and the measurement error was low (SEM = 0.3 to 0.7 kg). Patients with CMT were signif-icantly weaker than normal for all foot and ankle muscle groups tested (p < 0.001). Strength ratios of inversion-to-eversion and plantarflexion-to-dorsiflexion were signifi-cantly higher in the patients with CMT and pes cavus compared to individuals with normal foot types (p> 0.01). Conclusions: Hand-held dynamometry is an objective an