Arthrodesis of the first metatarsophalangeal joint: a biomechanical study comparing memory compression staples, cannulated screws, and a dorsal plate.

ABSTRACT

Arthrodesis of the first metatarsophalangeal joint of 21 matched pairs of cadaver toes was performed in order to compare the strength of three methods of internal fixation 1. two crossed cannulated screws, 2. a dorsal plate with an oblique 0.062 K-wire, and 3. two compression staples with an oblique 0.062 K-wire. Biomechanical testing with plantar force was carried out, and gapping across the fusion site was measured. Stiffness, load to 1-mm displacement, and force to failure was determined for each specimen. Both the plate and screw constructs were statistically stronger in force to failure and initial stiffness than the compression construct. Compression staples have an advantage in their ease of insertion and theoretical continuous compressive force across an arthrodesis site, but should be supplemented with a cast or other external immobilization until union is achieved.