Biomechanical Comparison of Hook Plate vs Headless Compression Screw Fixation of Large Fifth Metatarsal Base Avulsion Fractures.

BACKGROUND

Debate exists on the optimum fixation construct for large avulsion fractures of the fifth metatarsal base. We compared the biomechanical strength of 2 headless compression screws vs a hook plate for fixation of these fractures.

METHODS

Large avulsion fractures were simulated on 10 matched pairs of fresh-frozen cadaveric specimens. Specimens were assigned to receive two 2.5-mm headless compression screws or an anatomic fifth metatarsal hook plate, then cyclically loaded through the plantar fascia and metatarsal base. Specimens underwent 100 cycles at 50%, 75%, and 100% physiological load for a total of 300 cycles.

RESULTS

The hook plate group demonstrated a significantly higher number of cycles to failure compared with the screw group (270.7 ± 66.0 [range 100-300] cycles vs 178.6 ± 95.7 [range 24-300] cycles, respectively; P = .039). Seven of 10 hook plate specimens remained intact at the maximum 300 cycles compared with 2 of 10 screw specimens. Nine of 10 plate specimens survived at least 1 cycle at 100% physiologic load compared with 5 of 10 screw specimens.

CONCLUSION

A hook plate construct was biomechanically superior to a headless compression screw construct for fixation of large avulsion fractures of the fifth metatarsal base.

CLINICAL RELEVANCE: Whether using hook plates or headless compression screws, surgeons should consider protecting patient weight-bearing after fixation of fifth metatarsal base large avulsion fracture until bony union has occurred.