IN-VIVO VALIDATION OF IN-VITRO TESTING OF HALLUCAL FLEXOR MECHANICS

Objective. The purpose of this study was to validate an in vitro metho d of testing first metatarsophalangeal joint mechanics. Design. We com pared the orientation of the resultant moment of hallucal plantarflexi on in cadaveric specimens undergoing loading of the flexor hallucis lo ngus to the plane of the active great toe plantarflexion moment in nor mal volunteers. Background. Frontal plane deviation of hallucal planta rflexion is a fundamental component of the altered biomechanics in hal lux valgus. Methods. The cadaveric model utilized dynamic loading of t he flexor hallucis longus and static loading of the remaining muscles of the great toe. the in vivo method involved measurement of force out put with isometric hallucal plantarflexion in the standing position. T he medial-lateral and superior-inferior forces as well as the angle of the resultant moment in the clinically relevant frontal plane for bot h groups were quantified. Results, We found no significant difference between the frontal plane forces of each group. The directional orient ations in the frontal plane also displayed a marked similarity, with a n average lateral deviation of 0.63 degrees (P = 0.99) for each group. Conclusions. The lack of a significant difference between the cadaver ic and clinical methods of finding the resultant hallucal moment indic ates that the cadaveric method accurately simulates in vivo internal f lexor muscular loading of the great toe.