Unicortical PEEK inset locking fixation for metacarpal fractures: a biomechanical study
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There are numerous constructs employed in the treatment of metacarpal fractures with varying degrees of success. While plate fixation commonly involves dorsal application of a bicortical non-locking plate, there has been recent exploration of other fixation options including unicortical locked plating. The purpose of this study was to evaluate the biomechanical integrity of a polyetheretherketone (PEEK) inset locking plate and, in doing so, compare it to standard plate fixation (utilizing a clinically proven bicortical non-locking titanium plate) in a simulated porcine metacarpal fracture model.
Reproducible mid-shaft fractures were created in porcine second metacarpals. The fractured specimens were reduced and plated with either a bicortical non-locking plate or a unicortical locking plate with a PEEK locking design. Constructs were then loaded to failure in the same fashion as performed to create the fracture. Peak load was measured as the apex on the load-to-failure deflection curve. Stiffness was calculated as the linear slope on the load-to-failure deflection curve. Data were analyzed via Student’s t test.
Unicortical locking constructs failed at 344 ± 119 N, while bicortical non-locking constructs were found to fail at 277 ± 101 N (p = 0.19). The unicortical locking constructs demonstrated a stiffness of 80 ± 36 N/mm compared with the bicortical non-locking constructs (69 ± 36 N/mm) although again the difference was not found to be statistically different (p = 0.49).
Based on this study, a locked plating construct using a polymer mechanism provides an interesting new locking fixation method for small bone fractures and with our limited number of specimens tested, provided at least a similar strength and rigidity profile in comparison with bicortical fixation in the treatment of metacarpal fractures.
KeywordsInternal fixation Bending load polyetheretherketone (PEEK) Porcine metacarpal Failure
Hardware for this study was provided by TriMed, Inc., Santa Clarita, CA. Dr. Isaacs has received consultant fees and travel expenses from TriMed, Inc. Partial financial support was received from the Richmond Eye and Ear Healthcare Alliance Research and Education Fund.
Conflict of interest
Dr. Mudrick reports non-financial support from TriMed, during the conduct of the study. Dr. Isaacs reports personal fees from TriMed, during the conduct of the study; personal fees from TriMed, outside the submitted work. Dr. Wayne has nothing to disclose. Mr. Owen has nothing to disclose.
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