Metatarsal Length does not Correlate with Maximal Peak Pressure and Maximal Force

BACKGROUND: Primary metatarsalgia of the lesser metatarsals is common and caused by mechanical overload of the affected metatarsal heads. Increased metatarsal length generally is believed to be a factor in the development of primary metatarsalgia. However, there is no clear biomechanical evidence supporting this theory. QUESTIONS/PURPOSES: We asked whether metatarsal length correlated with plantar-loading parameters under the corresponding metatarsal heads. PATIENTS AND METHODS: We prospectively followed two groups of patients 46 (51 feet) with and 45 (51 feet) without metatarsalgia. Each foot was physically examined and underwent standardized full-weightbearing radiography and dynamic pedobarography to assess maximal peak pressure and maximal force under the first, second, and third metatarsal heads. We correlated the relative length of the first and third metatarsals with the corresponding two plantar-loading parameters. We compared maximal peak pressure and maximal force in patients with metatarsalgia with those of symptom-free patients. RESULTS: The relative length of the first and third metatarsals did not correlate (r < 0.13) with the maximal peak pressure or maximal force under the corresponding metatarsal heads. Maximal force under the first metatarsal head was decreased in the metatarsalgia group. There was no difference in maximal peak pressure between the metatarsalgia and nonmetatarsalgia groups. CONCLUSIONS: Relative metatarsal length had no influence on plantar-loading parameters. Shortening of a symptomatic ray to decrease plantar-loading parameters cannot be supported from a biomechanical rationale.