Trompeter Alex, Christen Alexis, Gerber Claus, Hofstaetter Bernhard, Wipf Felix, Lowe Jason
City St George's University of London, St George's University Hospital, London, UK.
Stryker, Selzach, Switzerland.
Bone Joint Res. 2025 Aug 19;14(8):713-720. doi: 10.1302/2046-3758.148.BJR-2024-0479.R1.
Lateral locked plating of distal femoral fractures is widely reported, yet there remains a 9% to 19% incidence of mechanical failure. Obliquely directed "kickstand screws", from the metaphyseal portion of a plate toward far-sided articular subchondral bone, have been shown to improve construct stiffness. This study explores the impact of kickstand screws in a finite element analysis bone defect model, comparing plate and screw maximum stress and maximum locking screw forces either with or without the addition of kickstand screws.
A finite element analysis model of a lateral based femoral plate and fracture gap simulation was created, with material and construct data parameters regarding bone material, implant, and composite model identified. The addition of the upper, lower, or both kickstand screws in an anatomical precontoured lateral distal femoral plate were selected as the variables compared against the absence of kickstand screws. Screw and plate principal stresses (MPa) and locking screw mechanism force (N) were measured.
The addition of the upper kickstand screw or both kickstand screws led to an approximate 40% reduction of stress in the metaphyseal hole closest to the fracture. The addition of the lower, upper, and both kickstand screws led to a 23%, 32%, and 34% reduction of maximum stress in the metaphyseal screws, respectively. The addition of the lower kickstand screw led to a 19% reduction, while the upper or both kickstand screws led to a 23% reduction of maximum force experienced by the locking mechanism.
The addition of kickstand screws improves the mechanical performance of the construct, with reduced stresses experienced by the plate and metaphyseal screws. Furthermore, the maximum forces on the locking screw mechanism were shown to be significantly reduced, providing a protective effect to the polyaxial locking mechanism of the metaphyseal screw.
股骨远端骨折的外侧锁定钢板固定术已被广泛报道，但其机械性失败的发生率仍在9%至19%之间。从钢板的干骺端部分向远侧关节软骨下骨倾斜的“支架螺钉”已被证明可提高结构刚度。本研究在有限元分析骨缺损模型中探讨支架螺钉的影响，比较添加或不添加支架螺钉时钢板和螺钉的最大应力以及最大锁定螺钉力。
创建了一个基于外侧的股骨钢板和骨折间隙模拟的有限元分析模型，确定了关于骨材料、植入物和复合模型的材料和结构数据参数。选择在解剖预塑形的股骨远端外侧钢板中添加上部、下部或上下部支架螺钉作为变量，与不添加支架螺钉进行比较。测量螺钉和钢板的主应力（MPa）以及锁定螺钉机构力（N）。
添加上部支架螺钉或上下部支架螺钉均使最靠近骨折处的干骺端孔中的应力降低约40%。添加下部、上部和上下部支架螺钉分别使干骺端螺钉的最大应力降低23%、32%和34%。添加下部支架螺钉使锁定机构承受的最大力降低19%，而添加上部或上下部支架螺钉使锁定机构承受的最大力降低23%。
添加支架螺钉可改善结构的力学性能，降低钢板和干骺端螺钉所承受的应力。此外，锁定螺钉机构上的最大力显著降低，为干骺端螺钉的多轴锁定机构提供了保护作用。
