Article
Locked intraosseous nailing in transverse patella fractures – a biomechanical comparison to tension band wiring through cannulated screws
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Published: | October 23, 2017 |
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Objectives: Displaced transverse patella fractures require open reduction and internal fixation. State of the art stabilization techniques are tension band wiring (TBW) using Kirschner wires or cannulated screws. These techniques are associated with secondary fracture dislocation, implant migration, prominence of the implant, wound healing disturbances, and the need for implant removal. Recently, a prototype locked intraosseous patella nail was developed. The aim of the present study was to compare biomechanically the performance of this nail versus TBW using cannulated screws.
Methods: Seven paired fresh-frozen human cadaveric knees were stripped off all soft tissues except the extensor apparatus and a transverse osteotomy was created to simulate a transverse patella fracture. The pairs were randomly assigned to be fixed with either TBW using cannulated screws or the intraosseous nail.
Each specimen underwent a cyclic test of 5000 cycles by pulling on the quadriceps tendon, simulating active knee extension and passive knee flexion within 90° flexion and full knee extension. Anterior and articular fracture site displacement as well as interfragmentary rotation around the mediolateral axis were investigated with optical motion tracking.
Results and Conclusion: Interfragmentary rotation and anterior fracture site displacement remained without statistical significance between the two fixation methods throughout the test cycles, p ≥ 0.237. Differences for articular displacement remained non-significant after 100 and 500 cycles. After 1000 cycles intraosseous nailing revealed a trend to lower articular displacement in comparison to TBW, p = 0.063. The differences for articular displacement were significant after 2500 and 5000 cycles, p ≤ 0.043 (Figure 1 [Fig. 1]).
From biomechanical point of view the locked intraosseous patella nail is a valuable alternative to TBW using cannulated screws, keeping higher fragment congruency at the articular fracture site.