Effect of Dorsal Plate Positioning on Dorsiflexion Angle in Arthrodesis of the First Metatarsophalangeal Joint: A Cadaveric Study.

Background: The relationship between dorsal plate positioning and final dorsiflexion angle after first metatarsophalangeal (MTP) joint fusion has not been well established. The main purpose of this study was to investigate whether changes in dorsal plate positioning along the longitudinal axis affect fusion dorsiflexion angle, as excessive dorsiflexion angles can lead to poor clinical results.

Methods: Ten cadaver foot specimens were randomly assigned to 2 groups for first MTP joint fusion: 1 group used a straight plate, and the other group used a 10-degree precontoured plate. After routine preparation, the plates were placed in an "ideal" position based on clinical and radiological examination. The plates were then moved proximally 3 mm and 6 mm from the initial site, with repeat imaging completed at each position. The radiological dorsiflexion angle was determined for each position, and the results were assessed.

Results: Placement of both straight and precontoured plates at positions more proximal from the initial position led to significant increases in dorsiflexion angles (P = .04), although the percentage change was larger in the precontoured plate group (P = .01). While placement of the plate 3 mm proximal from the perceived "ideal" position did increase the dorsiflexion angle, the percentage of specimens with dorsiflexion angles in the suggested optimal range changed minimally. Positioning at 6 mm from the starting point, however, led to significantly increased dorsiflexion angles for both plates (P = .004).

Conclusion: Positioning the dorsal plate at more proximal locations leads to increasing dorsiflexion angles. Precontoured plates are more likely to lead to excessive dorsiflexion compared with straight plates regardless of plate position.

Clinical Relevance: Fusion at excessive dorsiflexion angles can be minimized with appropriate selection and proper positioning of the dorsal fusion plate along the longitudinal axis.