Biomechanical Study Concerning the Types of Resection in Arthrodesis of First Metatarsophalangeal Joint.

This work concerns a biomechanical study aiming to ascertain the optimal type of joint resection when performing a joint arthrodesis. A 3-dimensional digital model of the first metatarsophalangeal joint including the entire first metatarsal bone and proximal phalanx using CT scans of the forefoot was created. Using this computer model, 4 types of resections; ball-and-socket, flat-on-flat, wedge 90°, and wedge 100° were simulated. Parameters measured using this model were the force necessary to separate the 2 fused surfaces, the surface area of the resected surfaces and the shortening of the first ray. By measuring the reactive force necessary to separate the phalanx from the first metatarsal, the 90° wedge resection was found to be the most stable, with comparable results in the case of the 100° wedge resection. Wedge resections are also more favorable when comparing the shortening of the first ray. Wedge resections, though being more technically difficult to perform prove to be the most stable for metatarsophalangeal joint-1 arthrodesis using this model.