Biomechanical Evaluation of a Locking and Nonlocking Reconstruction Plate in an Osteoporotic Calcaneal Fracture Model

Abstract

Background: This study evaluated the effects of locking vs nonlocking configuration on the biomechanical performance of a calcaneal reconstruction plate in an osteoporotic cadaveric model. Materials and Methods: A Saunders II B type calcaneal fracture was created in ten matched pair of cadaveric calcanei. Each pair was fixed with the Ascension calcaneal reconstruction plate using either locking or nonlocking screws in the same hole pattern. Specimens were axially loaded for 1000 cycles through the talus followed by load to failure. Statistical comparisons were made between the locking and nonlocking constructs on the displacements during cyclic loading as well as construct stiffness and load achieved at selected fragment displacements. Results: No significant difference was detected between the locking and nonlocking constructs in displacement during cyclic loading ( p >0.2) for the numbers available. Similarly no significant difference was found in stiffness of the constructs between the groups: 445.7 ± 148.8 (N/mm ± SD) for the locking plate and 395.2 ± 127.7 for the nonlocking plate ( p >0.14). The load achieved at 2 mm displacement of the posterior fragment for the two groups were not different: locking plate at 744.6 ± 237.2 N and nonlocking plate at 739.3± 269.7 N ( p >0.99). Conclusion: This study did not reveal a mechanical advantage to locking technology for calcaneal fractures with the selected plate and fracture model. Clinical Relevance: While locking plate technology has shown mechanical advantages for fracture management in other osteoporotic models, in our fracture model and plating construct, this was not found. It is still unclear which fixation technique is most beneficial in these calcaneal fractures.