Stability of Radial Head and Neck Fractures: A Biomechanical Study of Six Fixation Constructs With Consideration of Three Locking Plates.

Purpose: Open reduction and internal fixation of radial neck fractures can lead to secondary loss of reduction and nonunion due to insufficient stability. Nevertheless, there are only a few biomechanical studies about the stability achieved by different osteosynthesis constructs. Methods: Forty-eight formalin-fixed, human proximal radii were divided into 6 groups according to their bone density (measured by dual-energy x-ray absorptiometry). A 2.7-mm gap osteotomy was performed to simulate an unstable radial neck fracture, which was fixed with 3 nonlocking implants: a 2.4-mm T plate, a 2.4-mm blade plate, and 2.0-mm crossed screws, and 3 locking plates: a 2.0-mm LCP T plate, a 2.0-mm 6x2 grid plate, and a 2.0-mm radial head plate. Implants were tested under axial (N/mm) and torsional (Ncm/°) loads with a servohydraulic materials testing machine. Results: The radial head plate was significantly stiffer than all other implants under axial as well as under torsional loads, with values of 36 N/mm and 13 Ncm/°. The second-stiffest implant was the blade plate, with values of 20 N/mm and 6 Ncm/°. The weakest implants were the 2.0-mm LCP, with values of 6 N/mm and 2 Ncm/°, and the 2.0-mm crossed screws, with values of 18 N/mm and 2 Ncm/°. The 2.4-mm T plate, with values of 14 N/mm and 4 Ncm/°, and the 2.0-mm grid plate, with values of 8 N/mm and 4 Ncm/° came to lie in the midfield. Conclusions: The 2.0-mm angle-stable plates—depending on their design—allow fixation with comparable or even higher stability than the bulky 2.4-mm nonlocking implants and 2.0-mm crossed screws. [Copyright &y& Elsevier]