AO Research Institute Davos, Davos, Switzerland.
Department of Orthopaedic and Trauma Surgery, Lucerne Cantonal Hospital, Lucerne, Switzerland.
Arch Orthop Trauma Surg. 2022 Dec;142(12):3787-3796. doi: 10.1007/s00402-021-04239-7. Epub 2021 Nov 8.
Recently, two novel concepts for intramedullary nailing of trochanteric fractures using a helical blade or interlocking dual screws have demonstrated advantages as compared to standard single-screw systems. However, these two concepts have not been subjected to a direct biomechanical comparison so far. The aims of this study were to investigate in a human cadaveric model with low bone quality (1) the biomechanical competence of nailing with the use of a helical blade versus interlocking screws, and (2) the effect of cement augmentation on the fixation strength of the helical blade.
Twelve osteoporotic and osteopenic human cadaveric femoral pairs were assigned for pairwise implantation using either a short TFN-ADVANCED Proximal Femoral Nailing System (TFNA) with a helical blade head element or a short TRIGEN INTERTAN Intertrochanteric Antegrade Nail (InterTAN) with interlocking screws. Six osteoporotic femora, implanted with TFNA, were augmented with bone cement. Four groups were created: group 1 (TFNA) paired with group 2 (InterTAN), both consisting of osteopenic specimens, and group 3 (TFNA augmented) paired with group 4 (InterTAN), both consisting of osteoporotic specimens. An unstable trochanteric AO/OTA 31-A2.2 fracture was simulated and all specimens were tested until failure under progressively increasing cyclic loading.
Stiffness in group 3 was significantly higher versus group 4, p = 0.03. Varus (°) and femoral head rotation around the femoral neck axis (°) after 10,000 cycles were 1.9 ± 1.0/0.3 ± 0.2 in group 1, 2.2 ± 0.7/0.7 ± 0.4 in group 2, 1.5 ± 1.3/0.3 ± 0.2 in group 3 and 3.5 ± 2.8/0.9 ± 0.6 in group 4, being significantly different between groups 3 and 4, p = 0.04. Cycles to failure and failure load (N) at 5° varus or 10° femoral head rotation around the neck axis in groups 1-4 were 21,428 ± 6020/1571.4 ± 301.0, 20,611 ± 7453/1530.6 ± 372.7, 21,739 ± 4248/1587.0 ± 212.4 and 18,622 ± 6733/1431.1 ± 336.7, being significantly different between groups 3 and 4, p = 0.04.
Nailing of trochanteric femoral fractures with use of helical blades is comparable to interlocking dual screws fixation in femoral head fragments with low bone quality. Bone cement augmentation of helical blades provides significantly greater fixation strength compared to interlocking screws constructs.
最近，两种用于股骨转子间骨折髓内固定的新型概念，即螺旋刀片或交锁双钉，与标准单钉系统相比具有优势。然而，这两种概念尚未进行直接的生物力学比较。本研究的目的是在低骨质量的人体尸体模型中（1）研究使用螺旋刀片与交锁螺钉的固定能力，（2）研究骨水泥增强对螺旋刀片固定强度的影响。
将 12 对骨质疏松和骨质减少的人体股骨尸体配对，分别使用短 TFN-ADVANCED 股骨近端髓内钉系统（TFNA）的螺旋刀片头元件或短 TRIGEN INTERTAN 转子间顺行钉（InterTAN）进行植入。将 6 根骨质疏松股骨用骨水泥增强。创建了 4 组：组 1（TFNA）与组 2（InterTAN）配对，均由骨质减少的标本组成，组 3（TFNA 增强）与组 4（InterTAN）配对，均由骨质疏松标本组成。模拟不稳定的股骨转子间 A/O/OTA 31-A2.2 骨折，并在逐渐增加的循环载荷下对所有标本进行测试，直至失效。
组 3 的刚度明显高于组 4，p=0.03。在 10,000 次循环后，组 1 的内翻（°）和股骨颈轴周围股骨头旋转（°）分别为 1.9±1.0/0.3±0.2，组 2 为 2.2±0.7/0.7±0.4，组 3 为 1.5±1.3/0.3±0.2，组 4 为 3.5±2.8/0.9±0.6，组 3 和组 4 之间存在显著差异，p=0.04。组 1-4 的失效循环和失效载荷（N）分别为 21,428±6020/1571.4±301.0、20,611±7453/1530.6±372.7、21,739±4248/1587.0±212.4 和 18,622±6733/1431.1±336.7，组 3 和组 4 之间存在显著差异，p=0.04。
在低骨质量的股骨头骨折中，螺旋刀片髓内固定与交锁双钉固定具有可比性。与交锁螺钉结构相比，螺旋刀片的骨水泥增强可提供更高的固定强度。
