Roche Christopher P, Stroud Nicholas J, Flurin Pierre-Henri, Wright Thomas W, Zuckerman Joseph D, DiPaola Matthew J
Exactech, Gainesville, FL, USA.
Bordeaux-Merignac Clinic, Bordeaux-Merignac, France.
J Shoulder Elbow Surg. 2014 Sep;23(9):1388-94. doi: 10.1016/j.jse.2014.01.050. Epub 2014 Apr 13.
In this glenoid loosening study, we compared the fixation strength of multiple generic reverse shoulder glenoid baseplates that differed only in backside geometry and shape and size to optimize design from a fixation perspective.
The fixation strength of 4 generic baseplates was quantified in a low-density polyurethane substrate to isolate the contribution of baseplate profile and size (25 mm circular vs 25 × 34 mm oval) and backside geometry (flat back vs curved back) on fixation using 2 center-of-rotation glenospheres (0 mm and 10 mm lateral). The cyclic test simulated 55° of abduction as a 750 N load was continuously applied to induce a variable shear and compressive load. Before and after cyclic loading, baseplate displacement was measured in the directions of the applied static shear and compressive loads. Each generic baseplate was cyclically tested 7 times with each offset glenosphere for a total of 56 samples.
Circular baseplates were associated with significantly more shear displacement in both the superior-inferior (SI) and anterior-posterior (AP) directions after cyclic loading than oval baseplates. No such significant differences in fixation were observed between flat-back and curved-back baseplates. Circular baseplates were also associated with significantly more SI and AP shear displacement with 10 mm glenospheres than with 0 mm glenospheres. No significant difference in SI or AP motion was observed with oval baseplates between 0 mm and 10 mm glenospheres.
Our results suggest that baseplate shape and size affects fixation strength more than backside geometry. The 25 × 34 mm oval baseplates showed better fixation characteristics than their 25 mm circular counterparts; no discernible difference in fixation was observed between flat-back and curved-back baseplates.
在本肩胛盂松动研究中，我们比较了多种通用型反向肩关节肩胛盂基板的固定强度，这些基板仅在背面几何形状、形状和尺寸方面存在差异，以便从固定角度优化设计。
在低密度聚氨酯基质中对4种通用基板的固定强度进行量化，以分离基板轮廓和尺寸（25mm圆形与25×34mm椭圆形）以及背面几何形状（平背与曲背）对使用2种旋转中心球头（0mm和10mm外侧）固定的影响。循环测试模拟55°外展，同时持续施加750N载荷以诱导可变的剪切和压缩载荷。在循环加载前后，在施加的静态剪切和压缩载荷方向上测量基板位移。每种通用基板与每个偏移球头进行7次循环测试，共56个样本。
循环加载后，圆形基板在上下（SI）和前后（AP）方向上的剪切位移明显多于椭圆形基板。平背和曲背基板之间未观察到如此显著的固定差异。圆形基板在使用10mm球头时的SI和AP剪切位移也明显多于使用0mm球头时。椭圆形基板在0mm和10mm球头之间的SI或AP运动未观察到显著差异。
我们的结果表明，基板的形状和尺寸对固定强度的影响大于背面几何形状。25×34mm椭圆形基板显示出比25mm圆形基板更好的固定特性；平背和曲背基板之间在固定方面未观察到明显差异。
