Kwon Brian K, Goertzen Darrell J, O'Brien Peter J, Broekhuyse Henry M, Oxland Thomas R
Division of Orthopaedic Engineering Research, Departmentof Orthopaedics, Vancouver General Hospital, British Columbia, Canada.
J Bone Joint Surg Am. 2002 Jun;84(6):951-61. doi: 10.2106/00004623-200206000-00009.
Proximal humeral fractures are common injuries, and numerous surgical methods have been described for their treatment. The biomechanical characteristics of various internal fixation devices that are used to treat these fractures have not been extensively studied, nor has the potential beneficial effect of calcium phosphate cement supplementation.
We used a cadaveric three-part proximal humeral osteotomy model to perform a biomechanical evaluation of three types of internal fixation devices: a cloverleaf plate, an angled blade-plate, and Kirschner wires. The effect of supplementing the fixation with SRS (Skeletal Repair System) calcium phosphate cement was evaluated as well. Eighteen pairs of fresh-frozen humeri were obtained, and the bone-mineral density of each specimen was measured. In each pair, one specimen was secured with internal fixation alone and the contralateral specimen was secured with internal fixation combined with calcium phosphate cement. The specimens were tested cyclically in abduction and in external rotation for 250 cycles to evaluate interfragmentary motion. The specimens were then loaded to failure in external rotation to measure torsional load to failure and torsional stiffness.
Overall, there were no significant differences between the specimens treated with the blade and cloverleaf plates, whereas the specimens treated with Kirschner wires demonstrated more interfragmentary motion, less stiffness, and lower torque to failure. In general, supplementation with calcium phosphate cement led to significant improvements in the mechanical performance of all three forms of internal fixation as demonstrated by a significant decrease in interfragmentary motion, a significant increase in torque to failure, and a significant increase in torsional stiffness. The addition of calcium phosphate cement increased the stiffness of even the most osteoporotic specimens to levels that were higher than those of the most osteodense specimens that had been treated with internal fixation alone.
The initial biomechanical properties of internal fixation as measured with use of a proximal humeral osteotomy model and three methods of fixation were significantly improved by the addition of calcium phosphate cement.
肱骨近端骨折是常见损伤，已有多种手术方法用于治疗。用于治疗这些骨折的各种内固定装置的生物力学特性尚未得到广泛研究，磷酸钙骨水泥补充的潜在有益效果也未得到研究。
我们使用尸体三部分肱骨近端截骨模型对三种内固定装置进行生物力学评估：三叶形钢板、角状刃板和克氏针。还评估了用SRS（骨骼修复系统）磷酸钙骨水泥补充固定的效果。获取18对新鲜冷冻肱骨，测量每个标本的骨密度。在每对标本中，一个标本仅用内固定固定，对侧标本用内固定结合磷酸钙骨水泥固定。对标本进行外展和外旋循环测试250次，以评估骨折块间运动。然后将标本加载至外旋失败，以测量失败时的扭转负荷和扭转刚度。
总体而言，使用刃板和三叶形钢板治疗的标本之间没有显著差异，而使用克氏针治疗的标本表现出更多的骨折块间运动、更低的刚度和更低的失败扭矩。一般来说，补充磷酸钙骨水泥导致所有三种内固定形式的力学性能显著改善，表现为骨折块间运动显著减少、失败扭矩显著增加和扭转刚度显著增加。添加磷酸钙骨水泥甚至使最骨质疏松标本的刚度提高到高于仅用内固定治疗的最骨密度标本的水平。
通过添加磷酸钙骨水泥，使用肱骨近端截骨模型和三种固定方法测量的内固定初始生物力学性能得到显著改善。
