Gagliano Jeffrey R, Helms Sarah M, Colbath Gregory P, Przestrzelski Breanne T, Hawkins Richard J, DesJardins John D
Boulder Bone and Joint, Boulder and Louisville, CO, USA.
Department of Bioengineering, Clemson University, Clemson, SC, USA.
J Shoulder Elbow Surg. 2017 Jul;26(7):1113-1120. doi: 10.1016/j.jse.2017.01.018. Epub 2017 Mar 27.
Glenoid component loosening is common in total shoulder arthroplasty (TSA), often resulting from the mechanical interaction of glenohumeral components. This cadaveric study was performed to evaluate and to compare commercially available onlay and inlay glenoid prosthetic designs with respect to loading characteristics and loosening.
Sixteen prescreened cadaveric shoulders (8 matched pairs) underwent either onlay or inlay TSA. We created a custom glenohumeral loading model and used cycles of 5 mm anterior-posterior humeral translation to simulate a rocking-horse loosening mechanism for all testing. Articular TekScan measurements were performed with 9.1 kg (88.9 N) of glenohumeral compression before and after TSA. Fatigue testing was performed with 34.0 kg (333.6 N) of glenohumeral compression using high-definition video to document gross glenoid loosening. Testing ended with gross loosening or a maximum of 4000 cycles. Mean contact area, pressure, and joint reaction force were used to compare the 2 glenoid designs.
In both implant types, contact area decreased and pressure increased after TSA (P < .0001). Force increased at the onlay component edge only (P = .0012) compared with native glenoid testing. Force was greater in the onlay vs. the inlay implants (P < .0001). During fatigue testing, all onlay glenoid components exhibited gross loosening at a mean of 1126 cycles (range, 749-1838), whereas none of the inlay glenoid components exhibited gross loosening (P < .0001).
The inlay glenoid implant exhibited biomechanical characteristics favoring stability and decreased loosening compared with the onlay glenoid implant in this cadaveric model.
在全肩关节置换术（TSA）中，肩胛盂假体松动很常见，通常是由肱盂部件的机械相互作用导致的。本尸体研究旨在评估和比较市售的覆盖式和嵌入式肩胛盂假体设计在负荷特性和松动方面的情况。
对16个预先筛选的尸体肩关节（8对匹配）进行覆盖式或嵌入式TSA。我们创建了一个定制的肱盂负荷模型，并使用5毫米的肱骨头前后平移循环来模拟所有测试中的摇马松动机制。在TSA前后，使用9.1千克（88.9牛）的肱盂压缩力进行关节TekScan测量。使用34.0千克（333.6牛）的肱盂压缩力进行疲劳测试，使用高清视频记录肩胛盂的明显松动情况。测试在出现明显松动或最多4000个循环时结束。使用平均接触面积、压力和关节反应力来比较两种肩胛盂设计。
在两种植入类型中，TSA后接触面积均减小，压力均增加（P <.0001）。与天然肩胛盂测试相比，仅覆盖式部件边缘的力增加（P =.0012）。覆盖式植入物的力大于嵌入式植入物（P <.0001）。在疲劳测试中，所有覆盖式肩胛盂部件在平均1126个循环（范围749 - 1838）时均出现明显松动，而嵌入式肩胛盂部件均未出现明显松动（P <.0001）。
在这个尸体模型中，与覆盖式肩胛盂植入物相比，嵌入式肩胛盂植入物表现出有利于稳定性和减少松动的生物力学特性。
