Muscle in hallux valgus.

Muscle imbalance is cited widely as a major factor in the production of hallux valgus deformity. The authors, therefore, performed muscle biopsies in 57 patients (53 women and four men; average age, 45.3 years) to examine the histology and ultrastructure of the intrinsic muscles about the great toe. The biopsy study was correlated with gait analysis. In 53 biopsy specimens the muscles were found to be histologically abnormal, presenting myogenic and neurogenic alterations. Furthermore, ultrastructural examination showed enlarged mitochondria with paracrystalline inclusions in 31 of the 57 cases. Gait analysis showed an abnormal rollover pattern in 70% of the gait cycles examined in 19 symptomatic hallux valgus patients (18 women and one man), while in 19 asymptomatic volunteers (16 women and three men) 80% of the cycles examined were normal. The surface electromyographic (EMG) activity of the intrinsic muscles also was abnormal in the patient group when compared with the volunteer group; five different patterns of electrical activity were found. These findings may be interpreted as a result of chronic ischemia caused by the elevated pressure occurring within the foot during gait.