Stability of the offset V osteotomy: effects of fixation, orientation, and surgical translocation in polyurethane foam models and preserved cadaveric specimens.

Polyurethane foam models and cadaver specimens were used to examine the stability of the offset V first metatarsal osteotomy. Uniform osteotomies were performed in all specimens by using a specially designed jig. Specimens in the polyurethane foam model series (n = 10) varied with respect to fixation type, fixation orientation, and degree of lateral translocation of the osteotomy. All specimens were loaded to failure in an Instron testing machine (Instron, Canton, MA). The plantar wing-pin (Kirschner wire) osteotomy group showed statistically significantly greater stiffness (P =.0119) and load at failure (P =.0027) than the dorsal wing-pin group. Cadaveric offset V specimens received the same amount of capital fragment lateral translocation but had different fixation types and orientations. Using the identical protocol as the models, the cadaveric dorsal wing-screw group showed statistically significantly less displacement at failure than the plantar wing-screw, plantar wing-pin, and dorsal wing-pin groups (P =.0262). The dorsal wing-pin group with a synthetic tension band showed a statistically significant greater stiffness (P =.0054) and peak load at failure (P =.0004) compared with the dorsal wing-pin group without the tension band. The most stable offset V construct in the polyurethane foam model was the plantar wing-pin group. The preserved cadaveric specimens yielded different results. The cadaveric dorsal wing-pin group with the synthetic tension band showed superior stability compared with all other non-tension-band groups. These results indicate the importance of tension band effects provided by capsular and ligamentous structures, which are typically ignored in surgical optimization research.