Effects of tilt and glenosphere eccentricity on baseplate/bone interface forces in a computational model, validated by a mechanical model, of reverse shoulder arthroplasty
Effects of tilt and glenosphere eccentricity on baseplate/bone interface forces in a computational model, validated by a mechanical model, of reverse shoulder arthroplasty
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DOI：
10.1016/j.jse.2010.10.035
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发表时间：
2011-07-01
影响因子：
3
通讯作者：
Frankle, Mark A.
中科院分区：
文献类型：
--
作者：
Gutierrez, Sergio;Walker, Matthew;Frankle, Mark A.
假设/背景：对于严重肩袖缺失的患者，反向肩关节置换术的使用频率更高。有几种商业上可用的反肩装置，每一种都有不同的关节球选项。这项研究的目的是确定：(1)旋转中心位于同心偏心于基板中心的关节球的基板-骨界面处的力；以及(2)是否可以通过改变基板的倾斜来优化基板-骨力。方法：使用验证的计算机模型来比较3种基板倾斜：向下15度、中性或向上15度偏心偏移(下6 mm或外6 mm)的同心球和偏心偏移的球(下6 mm或外6 mm)。结果：对于外侧关节球和同心关节球，下方倾斜提供的力分布最均匀(基板上下部分的平均力差分别为11.3N和24.7N)，上方倾斜提供最不均匀的力分布(分别为109.3 N和78.7N)。对于下偏心球，下倾提供的力分布最不均匀(58.7N)，而中性倾斜提供的力分布最均匀(27.7N)。结论：这是首次研究下偏心球基底板下的力分布。尽管对于同心型和侧向偏移型的关节球，建议基板向下倾斜，但同样的建议可能对偏移度较低的关节球不利，需要进一步研究。证据水平：基础科学研究。(C)2011年《肩肘外科杂志》董事会成员。
Hypothesis/background: Reverse shoulder arthroplasty is being used with greater frequency for patients with severe rotator cuff deficiency. There are several commercially available reverse shoulder devices, each with different glenosphere options. The purpose of this study was to determine: (1) forces at the baseplate-bone interface in glenospheres with centers of rotation located concentrically and eccentrically to the center of the baseplate; and (2) if baseplate-bone forces can be optimized by altering tilt of the baseplate.Methods: A validated computer model was used to compare concentric glenospheres with neutral offset to eccentrically offset glenospheres (6 mm inferior or 6 mm lateral) in 3 baseplate tilts: 15 degrees inferior, neutral, or 15 degrees superior. A baseplate, simulated bone, screws, and humeral component were modeled, and forces underneath the baseplate were calculated as the arm was abducted through 90 degrees of glenohumeral motion.Results: For lateral and concentric glenospheres, inferior tilt provides the most even distribution of forces (mean difference in force between superior and inferior portions of baseplate: 11.3 N and 24.7 N, respectively) and superior tilt provides the most uneven distribution of forces (109.3 N and 78.7 N, respectively). For inferior eccentric glenospheres, inferior tilt provides the most uneven distribution of forces (58.7 N) and neutral tilt provides the most even distribution of forces (27.7 N).Conclusion: This is the first study to investigate force distribution under the baseplate in inferior eccentric glenospheres. Although inferior tilting of the baseplate is recommended for concentric and laterally offset glenospheres, this same recommendation may be detrimental to inferiorly offset glenospheres and warrants further investigation.Level of evidence: Basic Science Study. (C) 2011 Journal of Shoulder and Elbow Surgery Board of Trustees.