Montgomery Meredith L, Kim Stanley E, Dyce Jonathan, Pozzi Antonio
From the Comparative Orthopaedics Biomechanics Laboratory, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
The Ohio State University Veterinary Medical Center, Columbus, OH, USA.
BMC Vet Res. 2015 Mar 18;11:68. doi: 10.1186/s12917-015-0383-z.
Loss of dorsal acetabular rim (DAR) is a common sequela to canine hip dysplasia. The purpose of this study is to evaluate the effect of DAR loss on the initial stability of the cementless (BFX) acetabular cup. BFX cups were implanted into foam blocks reamed to resemble acetabulae with simulated 0, 25, 50, and 75% DAR loss. Models were tested in edge loading of the lateral surface of the cup with an indenter, and in centered loading with an articulated femoral prosthesis. Additionally, cups were implanted into paired cadaveric canine hemipelves with either no DAR depletion, or removal of 50% of the DAR, and acutely loaded to failure with an articulated femoral prosthesis.
Mean load measured at 1 mm cup displacement during edge loading was not significantly different in foam blocks with loss of 0, 25, 50, and 75% DAR (360 ± 124 N, 352 ± 42 N, 330 ± 81 N, 288 ± 43 N, respectively; P = 0.425). Mean load to failure with centered loads was greatest in blocks with 0% DAR loss (2828 ± 208 N; P < 0.001), but was not significantly different between 25, 50, and 75% DAR loss (2270 ± 301 N, 1924 ± 157 N, 1745 ± 118 N). In cadaveric testing, neither mean load to failure (P = 0.067), stiffness (P = 0.707), nor energy (P = 0.228) were significantly different in control hemipelves and those with 50% depletion of the DAR. Failure in all acetabulae occurred due to acetabular bone fracture at forces in supraphysiologic ranges.
BFX cup stability under normal physiologic loads does not appear to be compromised in acetabulae with up to 50% DAR loss.
髋臼背侧缘（DAR）缺失是犬髋关节发育不良的常见后遗症。本研究的目的是评估DAR缺失对非骨水泥型（BFX）髋臼杯初始稳定性的影响。将BFX髋臼杯植入经扩孔处理以模拟髋臼的泡沫块中，模拟DAR缺失0%、25%、50%和75%的情况。使用压头对髋臼杯外侧面进行边缘加载测试模型，并使用关节式股骨假体进行中心加载测试。此外，将髋臼杯植入成对的犬尸体半骨盆中，一种情况是不进行DAR切除，另一种情况是切除50%的DAR，然后使用关节式股骨假体对其进行急性加载直至失效。
在边缘加载过程中，当髋臼杯位移为1mm时，DAR缺失0%、25%、50%和75%的泡沫块所测得的平均载荷无显著差异（分别为360±124N、352±42N、330±81N、288±43N；P = 0.425）。中心加载时的平均失效载荷在DAR缺失0%的泡沫块中最大（2828±208N；P < 0.001），但在DAR缺失25%、50%和75%之间无显著差异（2270±301N、1924±157N、1745±118N）。在尸体测试中，对照半骨盆和DAR缺失50%的半骨盆在平均失效载荷（P = 0.067）、刚度（P = 0.707）或能量（P = 0.228）方面均无显著差异。所有髋臼的失效均是由于髋臼骨在超生理范围的力作用下发生骨折。
在DAR缺失高达50%的髋臼中，正常生理载荷下BFX髋臼杯的稳定性似乎未受影响。
