Stabilization of the posteromedial fragment in bicondylar tibial plateau fractures: a mechanical comparison of locking and nonlocking single and dual plating methods.

BACKGROUND: The objective of this study is to compare locking and nonlocking single and dual plating constructs in maintaining posteromedial fragment reduction in a bicondylar tibial plateau fracture model. We hypothesized that posteromedial fragment fixation with medial and lateral nonlocked constructs would tolerate higher loads than with lateral locked constructs alone.

METHODS: Thirty composite tibiae were fractured (AO 41-C1.3). Six constructs were tested: (1) lateral 3.5-mm conventional nonlocking proximal tibial plate (CP); (2) CP + posteromedial 3.5-mm limited contact dynamic compression plate; (3) CP + posteromedial 1/3 tubular plate (CP + 1/3 tubular); (4) 3.5-mm Zimmer Proximal Tibial Locking plate; (5) 3.5-mm Synthes Locking Compression plate; and (6) Less Invasive Stabilization System tibial plate. Specimens were cyclically loaded to failure or a maximum of 4000 N.

RESULTS: Failure occurred at the posteromedial fragment first. The CP + 1/3 tubular had the highest average load to failure (3040 N). The CP + 1/3 tubular demonstrated higher load at failure compared with the 3.5-mm Synthes Locking Compression plate (p = 0.0060) and the Less Invasive Stabilization System (p = 0.0360). The CP + 1/3 tubular did not demonstrate a difference in load at failure when compared with the CP (p = 0.4225), the CP + posteromedial 3.5-mm limited contact dynamic compression plate (p = 0.4799), or the 3.5-mm Zimmer Proximal Tibial Locking plate (p = 0.1595).

CONCLUSIONS: The posteromedial fragment tolerated higher loads with the CP + 1/3 tubular plate construct. The superiority of this construct may be caused by unreliable penetration of this fragment by the lateral locking screws.