Where should Kirschner wires be placed when fixing patella fracture with modified tension-band wiring? A finite element analysis

Abstract

BackgroundThe position of Kirschner wires (K-wires) has an influence on the outcome of modified tension-band wiring (MTBW) in fixing patella fractures. However, the instruction for K-wires positioning is not clear enough. This study tried to clarify the effect of K-wires positioning and provide evidence for a more definite instruction.MethodsThe sagittal position (SP) suitable for placing K-wires was evenly divided into SP 1–5 from anterior to posterior, and the finite element models of midpatella transverse fractures fixed by the figure-of-eight or figure-of-zero MTBW were built up at each SP. Separating displacement of the fracture, stress of the fracture, and stress of the internal fixations were measured at 45° knee flexion by using finite element analysis.ResultsThe separating displacement of the fracture was smaller at SP 3–5 (23% smaller than SP 1–2). From SP 1 to 5, the compression of the fracture surfaces increased (R = 0.99, P = 0.001); the improper stress area of the fracture surfaces decreased (R = − 0.96, P = 0.01), and so was the stress of K-wires (R = − 0.93, P = 0.02). However, the stress of stainless steel wires showed a stable trend.ConclusionsThe SP of K-wires plays a role in the function of MTBW in the surgical management of transverse patella fracture. At 45° knee flexion, posteriorly placed (close to the articular surface) K-wires enable optimal stability and stress for the fracture, which provides basis for the positioning of K-wires in clinical practice.

Comparison of the Therapeutic Effects of Tension Band with Cannulated Screw and Tension Band with Kirschner Wire on Patella Fracture

“…In addition, Kirschner wire loosening, bending, and the like may also be caused during knee exercise, resulting in treatment failure [ 9 ]. About 10%-20% of the patients suffered from displacement between fracture fragments, and 5% of the patients underwent two operations [ 10 ]. In view of this, medical workers made an improvement plan, namely, cannulated screw method, using a cannulated screw instead of Kirschner wire, cannulated screw can be embedded into bone tissue, causing less subcutaneous foreign body sensation, and can be used for annular binding fixation of more severely crushed fracture blocks without lacunae [ 11 , 12 ].…”

Management of comminuted patellar fracture fixation using modified cerclage wiring

“…At present, the treatment methods of patellar comminuted fracture include the following: circumferential cerclage wire fixation [2], modified tension band fixation [4, 5], nickel-titanium patella concentrator [6], cable-pin system [7], titanium cable cerclage [8], plate and screw fixation [9] and partial or total patellectomy [2, 10]. Partial or total patellectomy results in the destruction of the extensor mechanism and normal patellofemoral joint contact surface, which reduces knee joint function [1, 10, 11].…”

Application of a novel shape-memory alloy concentrator in displaced olecranon fractures: a report of the technique and mid-term clinical results

“…The technical advantage of TBW is that this method can convert tension at the fracture site, which is produced by tension band fixation into compression forces at the articular surface, making the fracture site closer and accelerating the healing of the fracture [32]. Furthermore, TBW allows for less soft-tissue stripping, which contributes to less damage [33].…”