Katthagen J C, Schwarze M, Bauer L, Meyer-Kobbe J, Voigt C, Hurschler C, Lill H
Department of Reconstructive and Trauma Surgery, Diakoniekrankenhaus Friederikenstift gGmbH, Humboldtstr. 5, 30169 Hannover, Germany.
Laboratory of Biomechanics and Biomaterials, Medizinische Hochschule Hannover (MHH), Anna-von-Borries-Str. 1-7, 30625 Hannover, Germany.
Orthop Traumatol Surg Res. 2015 Jun;101(4):431-5. doi: 10.1016/j.otsr.2015.01.018. Epub 2015 Apr 23.
The objective of this study was to evaluate the biomechanical effect of an additional unlocked calcar screw compared to a standard setting with three proximal humeral head screws alone for fixation of an unstable 2-part fracture of the surgical neck.
The additional calcar screw improves stiffness and failure load.
Fourteen fresh frozen humeri were randomized into two equal sized groups. An unstable 2-part fracture of the surgical neck was simulated and all specimens were fixed with the MultiLoc(®)-nail. Group I represented a basic screw setup, with three locked head screws and two unlocked shaft screws. Group II was identical with a supplemental unlocked calcar screw (CS). Stiffness tests were performed in torsional loading, as well as in axial and in 20° abduction/20° adduction modes. Subsequently cyclic loading and load-to-failure tests were performed. Resulting stiffness, displacement under cyclic load and ultimate load were compared between groups using the t-test for independent variables (α=0.05).
No significant differences were observed between the groups in any of the biomechanical parameters. Backing out of the CS was observed in three cases.
The use of an additional unlocked calcar screw does not provide mechanical benefit in locked nailing of an unstable 2-part fracture of the surgical neck.
本研究的目的是评估与仅使用三根近端肱骨头螺钉的标准固定方式相比，额外增加一枚非锁定距骨螺钉用于固定不稳定的肱骨外科颈二部分骨折的生物力学效果。
额外的距骨螺钉可提高刚度和破坏载荷。
将14具新鲜冷冻肱骨随机分为两组，每组样本量相等。模拟不稳定的肱骨外科颈二部分骨折，所有标本均使用MultiLoc（®）髓内钉固定。第一组为基本螺钉设置，包括三根锁定头螺钉和两根非锁定骨干螺钉。第二组在第一组基础上额外增加一枚非锁定距骨螺钉（CS）。分别在扭转加载、轴向加载以及20°外展/20°内收模式下进行刚度测试。随后进行循环加载和破坏载荷测试。使用独立变量t检验（α = 0.05）比较两组之间的刚度、循环载荷下的位移和极限载荷。
两组之间在任何生物力学参数上均未观察到显著差异。有3例出现距骨螺钉退出的情况。
对于不稳定的肱骨外科颈二部分骨折，在锁定髓内钉固定中使用额外的非锁定距骨螺钉并无机械优势。
