Role of screw proximity in the fixation of transverse patellar fractures with screws and a wire

Autor: Chih-Wei Chang, Yen-Nien Chen, Chun-Ting Li, Yu-Hsuan Chung, Chih-Han Chang, Yao-Te Peng
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Zdroj: Journal of Orthopaedic Surgery, Vol 26 (2018)
Druh dokumentu: article
ISSN: 2309-4990
23094990
52452298
DOI: 10.1177/2309499018789705
Popis: Purpose: Clinical and biomechanical studies have reported that using supportive screws and a wire instead of the common Kirschner wires for modified tension band wiring improves the stability of fractured patellae. However, the effect of screw proximity on the fixation of a fractured patella remains unclear. Therefore a numerical study was conducted to examine the effects of screw proximity on biomechanical responses in a simulated patellar fracture fixed using two parallel cannulated screws and anterior tension band wiring. Methods: A patellar model with a transverse fracture and loads simulating patellar tendon forces applied on the patella were used in the present simulation. The surgical fixation consisted of two 4.0-mm parallel partially threaded cannulated screws with a figure-of-eight tension band made using a 1.25-mm stainless steel wire. Biomechanical responses at two screw proximities, 5 and 10 mm from the leading edge of the patella, were investigated. Results: Superficial screw placement (5 mm) yielded higher stability, lower wire loads, and lower bone contact pressures than the deep placement (10 mm). The deep placement of screws exerted a higher load on the wire but a lower force on the screw than superficial placement did. Conclusion: This is the first numerical study to examine the effects of screw location on the fixation of a fractured patella using cannulated screws and tension band wiring. Considering the favorable biomechanical responses, superficial placement (5 mm below the leading edge of the patella) is recommended for screw insertion when treating a transverse fractured patella.
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