Biomechanical stability of simple coronal shear fracture fixation of the capitellum

Abstract Background Coronal shear fractures of the capitellum are rare and its surgical management is challenging without a defined gold standard. It was the purpose of this study to compare the biomechanical stability of 3 different internal fixation techniques for simple coronal shear fractures of the capitellum without posterior comminution. Methods Dubberley type IA fractures of the capitellum were created in 18 cadaveric elbows, which were age- and gender-matched to the following 3 groups of internal fixation: (1) two anteroposterior cannulated headless compression screws (group HCS); (2) two anteroposterior HCSs with additional anterior antiglide plate (group HCS + antiGP); and (3) a posterolateral distal humerus locking plate (group LP). All fixation techniques were cyclically loaded with 75 N over 2000 cycles and ultimately until construct failure. Data was analyzed for displacement, construct stiffness, and ultimate load to failure. Results Fragment displacement under cyclic loading with 2000 cycles did not show a significant difference (p=0.886) between the three groups. The HCS group compared with the antiGP and LP groups showed the highest stiffness (602 vs. 540 vs. 462 N/mm; p=0.417), without reaching statistically significant differences. Ultimate load to failure was also not significantly different comparing all three groups (p=0.297). Conclusions Simple coronal shear fractures of the capitellum are biomechanically equally stabilized by headless compression screws compared to an additional antiglide plate or a posterolateral locking distal humeral locking plate. In the view of the advantages of less (invasive) metal ware, the clinical use of two isolated anteroposterior headless compression screws appears reasonable.