Favre Philippe, Seebeck Jörn, Thistlethwaite Paul A E, Obrist Marc, Steffens Jason G, Hopkins Andrew R, Hulme Paul A
Zimmer Biomet, Sulzerallee 8, CH-8404 Winterthur, Switzerland.
Clin Biomech (Bristol). 2016 Feb;32:113-7. doi: 10.1016/j.clinbiomech.2015.12.004. Epub 2015 Dec 21.
Stemless humeral prostheses have been recently introduced. We measured for the first time their in vitro primary stability and analyzed the influence of three clinically important parameters (bone quality, implant size and post-operative loading) on micromotion. We also assessed if displacement sensors are appropriate to measure implant micromotion.
A stemless humeral implant (Sidus® Stem-Free Shoulder, Zimmer GmbH, Winterthur, Switzerland) was implanted in 18 cadaveric humeri. Three-dimensional motion of the implant was measured under dynamic loading at three load magnitudes with displacement sensors. Additionally, the relative motion at the bone-implant interface was measured with an optical system in four specimens.
Micromotion values derived from the displacement sensors were significantly higher than those measured by the optical system (P<0.005). Analysis of variance (ANOVA) indicated that bone density (P<0.0005) and load (P<0.0001) had a significant effect on implant micromotion, however the effect of implant size was not statistically significant (P=0.123).
Micromotion of this stemless design was shown to be significantly dependent on cancellous bone density. Patients must therefore have adequate bone quality for this procedure. The influence of load magnitude on micromotion emphasizes the need for controlled post-operative rehabilitation. Measurements with displacement sensors overestimate true interface micromotion by up to 50% and correction by an optical system is strongly recommended.
无柄肱骨头假体最近已被引入。我们首次测量了它们在体外的初始稳定性，并分析了三个临床上重要的参数（骨质、植入物尺寸和术后负荷）对微动的影响。我们还评估了位移传感器是否适合测量植入物的微动。
将一个无柄肱骨头植入物（Sidus®无柄肩部，Zimmer GmbH，瑞士温特图尔）植入18具尸体的肱骨中。使用位移传感器在三种负荷大小下动态加载时测量植入物的三维运动。此外，在四个标本中使用光学系统测量骨-植入物界面处的相对运动。
位移传感器得出的微动值显著高于光学系统测量的值（P<0.005）。方差分析（ANOVA）表明，骨密度（P<0.0005）和负荷（P<0.0001）对植入物微动有显著影响，然而植入物尺寸的影响无统计学意义（P=0.123）。
这种无柄设计的微动显示出显著依赖于松质骨密度。因此，患者进行此手术必须有足够的骨质。负荷大小对微动的影响强调了术后进行受控康复的必要性。位移传感器测量结果高估了真实的界面微动高达50%，强烈建议采用光学系统进行校正。
