A CADAVERIC BIOMECHANICAL STUDY OF CAST BOOTS USED IN THE EARLY POSTOPERATIVE PERIOD FOLLOWING FIRST METATARSOPHALANGEAL (MTP) JOINT ARTHRODESIS.

Abstract

Our cadaveric biomechanical study has demonstrated evidence to suggest that commercially available removable cast boots do provide the same reduction of force on a first MTP joint arthrodesis site, during the early post operative period, as a traditional fiberglass cast.

This study compares the effectiveness of three common models of walking boots to a fiberglass cast in protecting an arthrodesis of the first metatarsophalangeal (MTP) joint in the early post-operative period.

First MTP joint arthrodesis is commonly performed for various clinical problems. Weight bearing is encouraged post operatively, however the arthrodesis site must be protected from excessive forces until bony union is achieved.

Two cadaveric models of a 1^st MTP joint arthrodesis were prepared with a strain gauge placed at the joint, which provided a measure of the bending moment across the fusion site. Walking was simulated by applying a force to the sole of the cadaver foot at multiple positions, from the heel to the toe, representing the stages of gait from heel strike to toe off. Loading trials were performed using each of the walking boots and a fiberglass cast, with the moments across the joint compared.

For both specimens, the “Walkabout” by Smith & Nephew had the lowest mean moment. Specimen one showed that the “Walkabout” and “Sampson Walker” were both better than the “Equalizer” and fiberglass cast (p< 0.05). Specimen two showed that the “Walk-about” was better than all others (P< 0.05). Also, for both specimens, the “Walkabout” by Smith & Nephew had the smallest absolute maximum moment (P< 0.05). Our study has shown that removable cast boots do provide the same, if not more, reduction of force on a first MTP joint arthrodesis site as a traditional cast.