Aghayan Sam, Shepherd Duncan E T, Davis Edward T
School of Mechanical Engineering, University of Birmingham, Birmingham, UK.
Proc Inst Mech Eng H. 2013 Aug;227(8):913-8. doi: 10.1177/0954411913485057. Epub 2013 May 1.
The Birmingham mid head resection (BMHR) arthroplasty can be used as an alternative to conventional stemmed total hip arthroplasty in young patients unsuitable for hip resurfacing. This study investigated the effect of stem size on femoral neck fracture in the BMHR. Sawbones composite femurs were randomly allocated to one of the following groups: (1) unprepared femur with no prosthesis, (2) femur prepared with a Birmingham hip resurfacing (BHR) prosthesis, (3) femur prepared with a BMHR stem size 1 (BMHR-1) and (4) femur prepared with a BMHR stem size 3 (BMHR-3). Each femur was subjected to a compressive force using a materials testing machine until fracture of the femoral neck occurred. The highest force at fracture was in the unprepared femurs with a mean (±standard deviation) force at failure of 5.9 ± 0.2 kN. The mean force at failure for the femurs fitted with a prosthesis was 2.6 ± 0.4, 3.0 ± 0.4 and 3.5 ± 0.5 kN for the BHR, BMHR-1 and BMHR-3, respectively. Statistical analysis showed that the failure force for the unprepared femur was significantly (p<0.05) greater than that of the BHR, BMHR-1 and BMHR-3. There was a significant difference (p<0.05) between the force at failure for the BMHR-1 and BMHR-3, indicating that these two stem sizes have an effect on fracture force.
伯明翰中头切除术（BMHR）关节成形术可用于不适宜髋关节表面置换的年轻患者，作为传统带柄全髋关节置换术的替代方案。本研究调查了柄的尺寸对BMHR中股骨颈骨折的影响。将Sawbones复合股骨随机分为以下几组：（1）未准备且无假体的股骨，（2）用伯明翰髋关节表面置换术（BHR）假体准备的股骨，（3）用BMHR柄尺寸1（BMHR-1）准备的股骨，以及（4）用BMHR柄尺寸3（BMHR-3）准备的股骨。使用材料试验机对每根股骨施加压缩力，直至股骨颈发生骨折。骨折时的最大力出现在未准备的股骨中，失败时的平均（±标准差）力为5.9±0.2kN。对于安装了假体的股骨，BHR、BMHR-1和BMHR-3的失败时平均力分别为2.6±0.4、3.0±0.4和3.5±0.5kN。统计分析表明，未准备的股骨的失败力显著（p<0.05）大于BHR、BMHR-1和BMHR-3。BMHR-1和BMHR-3的失败力之间存在显著差异（p<0.05），表明这两种柄尺寸对骨折力有影响。
