Collins Melissa, Hart Adam, Hines Jerod, Steffen Thomas, Harvey Edward J, Martineau Paul A
McGill University, Division of Orthopedic Surgery, Montreal, Quebec, Canada.
J Orthop Trauma. 2014 Aug;28(8):470-5. doi: 10.1097/BOT.0000000000000021.
To determine the biomechanical properties of plating options for distal ulna fractures.
Fourth-generation ulna artificial bones were osteotomized and fixed with 4 different constructs: 2 locking compression plates (a straight 2.7-mm plate and a 2.4-mm T-plate) with both nonlocking and locking screws. The artificial bones underwent nondestructive tests to determine construct stiffness in flexion/extension and lateral bending. The final testing consisted of cyclical loading in axial torsion until implant failure.
The straight plate fixation construct was significantly stiffer than the T-plate construct for both flexion/extension bending (P < 0.001) and radial/ulnar bending (P < 0.05). Nonlocking screws provided significantly stiffer fixation in flexion bending than locking screws (P < 0.05); however, no difference was found in extension bending. Conversely, locking screws were significantly stiffer in radial/ulnar bending than the nonlocking screws (P < 0.05). Failure under torsional cyclical loading was significantly different among constructs. The straight plate with nonlocking construct withstood the most half-cycles. The mechanisms of failure were unique to each type of fixation.
These results do not show any clear biomechanical advantage of locked plating for fractures of the distal ulna. The increased stiffness associated with locked plating likely contributes to earlier and more pronounced failure mechanisms under repetitive axial torsion.
确定尺骨远端骨折钢板固定方式的生物力学特性。
将第四代尺骨人工骨截骨后用4种不同的固定方式固定：2种锁定加压钢板（一种2.7毫米直形钢板和一种2.4毫米T形钢板），分别使用非锁定螺钉和锁定螺钉。对人工骨进行无损测试以确定其在屈伸和侧方弯曲时的固定刚度。最终测试包括轴向扭转循环加载直至植入物失效。
在屈伸弯曲（P < 0.001）和桡尺侧弯曲（P < 0.05）方面，直形钢板固定结构均显著比T形钢板固定结构更硬。在屈伸弯曲时，非锁定螺钉提供的固定刚度显著高于锁定螺钉（P < 0.05）；然而，在伸展弯曲时未发现差异。相反，在桡尺侧弯曲时，锁定螺钉比非锁定螺钉显著更硬（P < 0.05）。不同固定结构在扭转循环加载下的失效情况有显著差异。非锁定结构的直形钢板承受的半周期数最多。每种固定类型的失效机制各不相同。
这些结果并未显示锁定钢板治疗尺骨远端骨折有任何明显的生物力学优势。锁定钢板相关的刚度增加可能导致在重复性轴向扭转下更早且更明显的失效机制。
