PDF(Pubmed)
Abstract：
OBJECTIVE: Total joint arthroplasty (TJA) has often been used to treat thumb carpometacarpal (CMC) osteoarthritis (OA). However, guidelines for the CMC prosthesis shape remain unclear. This study aimed to identify the effective shape of a ball-and-socket prosthesis in restoring the range of thumb motion after TJA.
METHODS: The participants were 10 healthy young adult men (22-32 years; 26.8 ± 3.57 [mean ± SD]). CT scans were performed in eight static limb positions during abduction and flexion. We defined three design variables (offset R, height H, and neck rotation angle Φ) as the variables that determine the basic shape of the ball-and-socket prosthesis. The ideal values of these design variables were examined based on the results of a 3D motion analysis, which evaluated the change in the posture of the first metacarpal (r, h, and φ corresponding to R, H, and Φ, respectively) relative to the center of rotation (COR) during abduction and flexion. We also simulated the effect of these design variables on the range of thumb motion after TJA using 3D CAD.
RESULTS: We found that the values of r and h averaged over all limb positions were 6.92 ± 1.60 mm and 51.02 ± 1.67 mm, respectively, showing that these values remained constant regardless of limb position. In contrast, φ changed significantly. The simulation results indicated that Φ affected the range of thumb motion after TJA, and Φ = 0° relatively reproduced all limb positions compared to other values.
CONCLUSIONS: Our results suggested that the desirable values of R and H were the average of r and h over several limb positions and that Φ = 0° was effective in restoring the range of thumb motion after TJA. Our results will provide surgeons with new guidelines for selecting a prosthesis.
METHODS: The participants were 10 healthy young adult men (22-32 years; 26.8 ± 3.57 [mean ± SD]). CT scans were performed in eight static limb positions during abduction and flexion. We defined three design variables (offset R, height H, and neck rotation angle Φ) as the variables that determine the basic shape of the ball-and-socket prosthesis. The ideal values of these design variables were examined based on the results of a 3D motion analysis, which evaluated the change in the posture of the first metacarpal (r, h, and φ corresponding to R, H, and Φ, respectively) relative to the center of rotation (COR) during abduction and flexion. We also simulated the effect of these design variables on the range of thumb motion after TJA using 3D CAD.
RESULTS: We found that the values of r and h averaged over all limb positions were 6.92 ± 1.60 mm and 51.02 ± 1.67 mm, respectively, showing that these values remained constant regardless of limb position. In contrast, φ changed significantly. The simulation results indicated that Φ affected the range of thumb motion after TJA, and Φ = 0° relatively reproduced all limb positions compared to other values.
CONCLUSIONS: Our results suggested that the desirable values of R and H were the average of r and h over several limb positions and that Φ = 0° was effective in restoring the range of thumb motion after TJA. Our results will provide surgeons with new guidelines for selecting a prosthesis.
摘要：
目的：全关节置换术（TJA）常被用于治疗拇指腕掌（CMC）骨关节炎（OA）。然而,CMC假体形状的指南仍不清楚。这项研究旨在确定TJA后恢复拇指运动范围的有效形状。
方法：参与者是10名健康的年轻成年男性（22-32岁；26.8±3.57[平均值±SD]）。在外展和屈曲期间，在八个静态肢体位置进行了CT扫描。我们定义了三个设计变量(偏移量R，高度H,和颈部旋转角度Φ）作为确定球窝假体基本形状的变量。根据3D运动分析的结果检查了这些设计变量的理想值，它评估了第一掌骨姿势的变化(r，h,和φ对应于R，H,和Φ，分别）相对于外展和屈曲期间的旋转中心（COR）。我们还使用3DCAD模拟了这些设计变量对TJA后拇指运动范围的影响。
结果：我们发现所有肢体位置的r和h平均值分别为6.92±1.60mm和51.02±1.67mm，分别,显示无论肢体位置如何，这些值都保持不变。相比之下,φ变化明显。仿真结果表明，Φ影响TJA后拇指的运动范围，与其他值相比，Φ=0°相对再现了所有肢体位置。
结论：我们的结果表明，R和H的期望值是多个肢体位置上r和h的平均值，并且Φ=0°可有效恢复拇指运动范围TJA后。我们的结果将为外科医生提供选择假体的新指南。
方法：参与者是10名健康的年轻成年男性（22-32岁；26.8±3.57[平均值±SD]）。在外展和屈曲期间，在八个静态肢体位置进行了CT扫描。我们定义了三个设计变量(偏移量R，高度H,和颈部旋转角度Φ）作为确定球窝假体基本形状的变量。根据3D运动分析的结果检查了这些设计变量的理想值，它评估了第一掌骨姿势的变化(r，h,和φ对应于R，H,和Φ，分别）相对于外展和屈曲期间的旋转中心（COR）。我们还使用3DCAD模拟了这些设计变量对TJA后拇指运动范围的影响。
结果：我们发现所有肢体位置的r和h平均值分别为6.92±1.60mm和51.02±1.67mm，分别,显示无论肢体位置如何，这些值都保持不变。相比之下,φ变化明显。仿真结果表明，Φ影响TJA后拇指的运动范围，与其他值相比，Φ=0°相对再现了所有肢体位置。
结论：我们的结果表明，R和H的期望值是多个肢体位置上r和h的平均值，并且Φ=0°可有效恢复拇指运动范围TJA后。我们的结果将为外科医生提供选择假体的新指南。
