Evaluating Wire Configurations for Tension Band Constructs using a Canine Greater Trochanteric Osteotomy Model

Abstract

Objective: To investigate the stability of four tension band wiring configurations alone without the contributions of K-wire stabilization. Study design: ex vivo experimental Sample population: Sixty-four tension band wiring constructs Methods: Four tension band configurations were applied to a metal trochanteric osteotomy model based on a canine femur: figure-of-eight with one twist (OT), figure-of-eight with two twists (TT), dual interlocking single loop (DISL), and double loop (DL). Configurations were mechanically tested under both monotonic loading (n = 8 per configuration) and incremental cyclic loading (n = 8 per configuration). Initial tension after tying, residual tension remaining after each cycle, and failure load at 2 mm of displacement (considered equivalent to clinical failure) were recorded. Results: The initial tension and the load to 2 mm of displacement was lower for OT wires compared to TT wires. The DL was the strongest and most stable configuration, generating greater initial tension, maintaining a greater percentage of residual tension under incremental cyclic loads, and resisting higher load before failure at 2 mm. Failure load was highly correlated with initial tension. Conclusion: This model enabled evaluation of tension band wire configuration independent of the fixation pin portion of the construct. Wire configurations that can be tightened to a greater tension during tying, like the DL, are better able to resist the tensile loads experienced by the construct. Clinical impact: In clinical situations where high tensile loads are expected, a tighter, more secure tension band wire configuration may be warranted.