Grünewald Dag, Langenmair Elia, Hirschmüller Anja, Maier Dirk, Südkamp Norbert P, Konstantinidis Lukas
1 Department of Orthopaedics and Trauma Surgery, Berufsgenossenschaftliche Unfallklinik Frankfurt am Main, Frankfurt am Main, Germany.
2 Department of Orthopaedics and Trauma Surgery, Loretto-Krankenhaus Freiburg, Freiburg im Breisgau, Germany.
Proc Inst Mech Eng H. 2019 Jul;233(7):706-711. doi: 10.1177/0954411919848625. Epub 2019 May 8.
The aim of this study was the dynamic biomechanical evaluation of a ready-to-use oil-based calcium phosphate cement paste implanted to augment intramedullary nail fixation of a three-part humeral head fracture model. Fractures in the osteoporotic bone are often fractures of the proximal humerus. Secondary fracture displacements due to cut-out in osteoporotic bone have been observed in up to 13% of cases. Procedures have been developed to augment fracture fixation with polymethylmethacrylate to increase stability, but there are still unsolved challenges relating to its material-specific properties. Calcium phosphate cement could be a biological alternative in the augmentation of osteoporotic fractures because of its more favourable material properties. Fracture fixation was performed on eight pairs of human cadaveric bones to stabilize a standardized three-part humeral head fracture model by implantation of the Targon PH (Braun-Aesculap AG, Tuttlingen, Germany) intramedullary nail and insertion of three head screws and two bicortical shaft screws. The procedure was randomized, and one bone of each pair received calcium phosphate cement augmentation. Custom-made cannulated screws with an open lateral slot facilitated augmentation, making it possible to cement the threaded portion of the screw (1-mL calcium phosphate cement/screw). After the calcium phosphate cement had hardened, the humeri were subjected to dynamic axial loading. Load was progressively increased, monitored by ultrasound-based motion analysis, and total deformation was recorded. Load testing continued until implant failure. The augmented group withstood significantly more cycles before implant failure. The average initial stiffness showed a significant difference between the two study groups. Ultrasonic sensor technology was used to measure angular displacement during testing and a significant difference was found. Calcium phosphate cement offers a potential alternative to implant augmentation in the treatment of osteoporotic humeral head fractures. Future studies are required to confirm these observations clinically in vivo.
本研究的目的是对一种即用型油基磷酸钙骨水泥糊剂进行动态生物力学评估，该糊剂用于增强三部分肱骨头骨折模型的髓内钉固定。骨质疏松性骨骨折常为肱骨近端骨折。在高达13%的病例中观察到骨质疏松性骨中因植入物松动导致的二次骨折移位。已开发出用聚甲基丙烯酸甲酯增强骨折固定以提高稳定性的方法，但其材料特定性能仍存在未解决的挑战。由于其更有利的材料性能，磷酸钙骨水泥可能是增强骨质疏松性骨折的一种生物替代物。对八对人体尸体骨骼进行骨折固定，通过植入Targon PH（德国图特林根的Braun-Aesculap AG公司）髓内钉以及插入三根头部螺钉和两根双皮质骨干螺钉来稳定标准化的三部分肱骨头骨折模型。该过程是随机的，每对骨骼中的一根接受磷酸钙骨水泥增强。带有开放侧槽的定制空心螺钉便于增强操作，使得能够用骨水泥填充螺钉的螺纹部分（每颗螺钉使用1毫升磷酸钙骨水泥）。在磷酸钙骨水泥硬化后，对肱骨进行动态轴向加载。载荷逐渐增加，通过基于超声的运动分析进行监测，并记录总变形。载荷测试持续进行直至植入物失效。增强组在植入物失效前承受的循环次数明显更多。两个研究组之间的平均初始刚度存在显著差异。在测试过程中使用超声传感器技术测量角位移，发现存在显著差异。磷酸钙骨水泥为治疗骨质疏松性肱骨头骨折的植入物增强提供了一种潜在的替代方法。未来需要进行研究以在临床体内证实这些观察结果。
