Zhelev Daniel, Hristov Stoyan, Zderic Ivan, Ivanov Stoyan, Visscher Luke, Baltov Asen, Ribagin Simeon, Stoffel Karl, Kralinger Franz, Winkler Jörg, Richards R Geoff, Varga Peter, Gueorguiev Boyko
AO Research Institute Davos, 7270 Davos, Switzerland.
Department of Orthopedics and Traumatology, University Hospital for Active Treatment, 8018 Burgas, Bulgaria.
Medicina (Kaunas). 2023 Sep 5;59(9):1604. doi: 10.3390/medicina59091604.
: Unstable proximal humerus fractures (PHFs) with metaphyseal defects-weakening the osteosynthesis construct-are challenging to treat. A new augmentation technique of plated complex PHFs with metaphyseal defects was recently introduced in the clinical practice. This biomechanical study aimed to analyze the stability of plated unstable PHFs augmented via implementation of this technique versus no augmentation. : Three-part AO/OTA 11-B1.1 unstable PHFs with metaphyseal defects were created in sixteen paired human cadaveric humeri (average donor age 76 years, range 66-92 years), pairwise assigned to two groups for locked plate fixation with identical implant configuration. In one of the groups, six-milliliter polymethylmethacrylate bone cement with medium viscosity (seven minutes after mixing) was placed manually through the lateral window in the defect of the humerus head after its anatomical reduction to the shaft and prior to the anatomical reduction of the greater tuberosity fragment. All specimens were tested biomechanically in a 25° adduction, applying progressively increasing cyclic loading at 2 Hz until failure. Interfragmentary movements were monitored by motion tracking and X-ray imaging. : Initial stiffness was not significantly different between the groups, = 0.467. Varus deformation of the humerus head fragment, fracture displacement at the medial humerus head aspect, and proximal screw migration and cut-out were significantly smaller in the augmented group after 2000, 4000, 6000, 8000 and 10,000 cycles, ≤ 0.019. Cycles to 5° varus deformation of the humerus head fragment-set as a clinically relevant failure criterion-and failure load were significantly higher in the augmented group, = 0.018. : From a biomechanical standpoint, augmentation with polymethylmethacrylate bone cement placed in the metaphyseal humerus head defect of plated unstable PHFs considerably enhances fixation stability and can reduce the risk of postoperative complications.
伴有干骺端缺损（会削弱骨合成结构）的不稳定型肱骨近端骨折（PHFs）治疗起来颇具挑战性。一种针对伴有干骺端缺损的复杂PHFs钢板固定的新型增强技术最近被引入临床实践。本生物力学研究旨在分析采用该技术进行增强与未增强的钢板固定不稳定型PHFs的稳定性。
在16对人尸体肱骨（供体平均年龄76岁，范围66 - 92岁）上制造出伴有干骺端缺损的三部分AO/OTA 11 - B1.1不稳定型PHFs，成对分配到两组，采用相同的植入物配置进行锁定钢板固定。在其中一组中，在肱骨头解剖复位至骨干后且大结节骨折块解剖复位之前，通过外侧窗口将6毫升中等粘度（混合后7分钟）的聚甲基丙烯酸甲酯骨水泥手动放置在肱骨头缺损处。所有标本在25°内收位进行生物力学测试，以2Hz的频率逐渐增加循环载荷直至失效。通过运动跟踪和X射线成像监测骨折块间的运动。
两组之间的初始刚度无显著差异，P = 0.467。在2000、4000、6000、8000和10000次循环后，增强组肱骨头骨折块的内翻变形、肱骨头内侧方面的骨折移位以及近端螺钉的迁移和穿出明显更小，P≤0.019。设定为临床相关失效标准的肱骨头骨折块内翻变形达5°的循环次数以及失效载荷在增强组显著更高，P = 0.018。
从生物力学角度来看，在钢板固定的不稳定型PHFs的肱骨头干骺端缺损处放置聚甲基丙烯酸甲酯骨水泥进行增强可显著提高固定稳定性，并可降低术后并发症的风险。
