Effect of First Ray Insufficiency and Metatarsal Index on Metatarsalgia in Hallux Valgus.

BACKGROUND Two concepts have been proposed to explain the etiology of metatarsalgia in hallux valgus patients: First, as the magnitude of hallux valgus increases, there is a mechanical overload of the lesser metatarsals. Second, increased relative lesser metatarsal length is a factor in the development of metatarsalgia. However, there is no current evidence that these structural factors lead to primary metatarsalgia. The purpose of the study was to evaluate the factors associated with metatarsalgia in hallux valgus patients. METHODS A cross-sectional study of 121 consecutive adult patients with non-arthritic hallux valgus was carried out. Binary logistic regression was performed to identify the effect of the clinical and demographic factors on the occurrence of metatarsalgia. One hundred twenty-one patients (184 feet) with hallux valgus were analyzed. The median weight was 65 kg (interquartile range 58-72). RESULTS Metatarsalgia was present in 84 (45.6%) feet. The binary logistic regression showed that lesser toe deformity (OR 2.6, 95% CI 0.2-0.5), gastrocnemius shortening (OR 5.8, 95% CI 2.8-12.3), metatarsal index (OR 0.3, 95% CI 0.2-0.5), and weight (OR 2.5, 95% CI 1.2-5.3) were significantly associated. CONCLUSION Metatarsalgia occurs in almost half of hallux valgus patients. It has a multifactorial etiology. Our findings contradict the common theory that both the magnitude of hallux valgus deformity and an increased length of the lesser metatarsals, by themselves, lead to primary metatarsalgia. Metatarsalgia was associated with Achilles shortening, excessive weight, and associated lesser toe deformity. These factors should be addressed in order to treat this disorder adequately. LEVEL OF EVIDENCE Level III, comparative series.