Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China.
School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
J Orthop Res. 2020 Jul;38(7):1566-1574. doi: 10.1002/jor.24711. Epub 2020 May 12.
Aseptic loosening of the glenoid component is one of the main reasons for the high revision rates of reverse total shoulder arthroplasty (RTSA). It has been reported that the bulky implant designs may lead to stress shielding. However, it is uncertain whether the shielding effect is severe enough to lead to bone resorption and glenoid loosening. The purpose of this study was to evaluate the level of stress-shielding and assess whether bone resorption plays a role in aseptic glenoid loosening following RTSA. A cadaveric in vitro test model was used to validate a finite element model (FEM) of the scapula. The FEM of the scapula, incorporating adaptive bone remodeling algorithms, was used to predict changes in postoperative bone density after RTSA. Changes in bone strength after implantation were also analyzed. The strain values predicted from the FEM of the scapula were in agreement with the in vitro measurements. Analysis of postoperative bone adaptation revealed that strain-induced bone resorption began at the peg of the implant and around the resected bone surface and then gradually expended to the peripheral regions. The bone strength also reduced postoperatively and appeared particularly around the implant peg. Strain-induced bone resorption is a likely source of the bone loss commonly observed in RTSA. The finite element glenoid bone remodeling simulation may be used as a tool to evaluate glenoid implant design.
肩盂假体无菌性松动是反式全肩关节置换术（RTSA）高返修率的主要原因之一。有报道称，体积庞大的植入物设计可能导致应力遮挡。然而，尚不确定这种屏蔽效应是否严重到足以导致骨吸收和肩盂松动。本研究旨在评估应力遮挡程度，并评估骨吸收是否在 RTSA 后无菌性肩盂松动中起作用。采用尸体体外测试模型验证肩胛骨的有限元模型（FEM）。将包含适应性骨重塑算法的肩胛骨 FEM 用于预测 RTSA 后术后骨密度的变化。还分析了植入物后的骨强度变化。肩胛骨 FEM 预测的应变值与体外测量值一致。术后骨适应分析表明，应变诱导的骨吸收始于植入物的钉和切除骨表面周围，然后逐渐扩展到周边区域。术后骨强度也降低了，尤其是在植入物钉周围。应变诱导的骨吸收可能是 RTSA 中常见的骨丢失的来源。有限元肩盂骨重塑模拟可用作评估肩盂植入物设计的工具。
