Biomechanical stability of simple coronal shear fracture fixation of the capitellum.

Abstract

Coronal shear fractures of the capitellum are rare, and their surgical management is challenging, without a defined gold standard. The purpose of this study was to compare the biomechanical stability of 3 different internal fixation techniques for simple coronal shear fractures of the capitellum without posterior comminution. Dubberley type IA fractures of the capitellum were created in 18 cadaveric elbows, which were age and sex matched to the following 3 internal fixation groups: (1) two anteroposterior cannulated headless compression screws (HCSs), (2) two anteroposterior HCSs with an additional anterior antiglide plate (antiGP), and (3) a posterolateral distal humeral locking plate (LP). All fixation techniques were cyclically loaded with 75 N over 2000 cycles and ultimately until construct failure. Data were analyzed for displacement, construct stiffness, and ultimate load to failure. Fragment displacement under cyclic loading with 2000 cycles did not show a significant difference (P = .886) between the 3 groups. The HCS group showed the highest stiffness compared with the HCS-antiGP and LP groups (602 N/mm vs. 540 N/mm vs. 462 N/mm, P = .417), without reaching a statistically significant difference. Ultimate load to failure was also not significantly different on comparison of all 3 groups (P = .297). Simple coronal shear fractures of the capitellum are biomechanically equally stabilized by HCSs compared with HCSs with an additional antiGP or a posterolateral distal humeral LP. In view of the advantages of less (invasive) metalware, the clinical use of 2 isolated anteroposterior HCSs appears reasonable.