Weiss Arnold-Peter C, Moore Douglas C, Infantolino Corinne, Crisco Joseph J, Akelman Edward, McGovern Robert D
Hand Surgery Research & Bioengineering Laboratories, Department of Orthopaedics, Brown Medical School, Rhode Island Hospital, Providence, RI 02905, USA.
J Hand Surg Am. 2004 Sep;29(5):796-803. doi: 10.1016/j.jhsa.2004.04.023.
This study was performed to compare metacarpophalangeal (MCP) joint mechanics after arthroplasty with 3 currently available silicone implants and to determine how postarthroplasty mechanics compares with the mechanics of the intact joint.
Planar 2-dimensional kinematic analysis was performed using digitized radiographs on 10 isolated fingers harvested from 5 fresh-frozen human cadavers. Radiopaque markers were affixed to the metacarpals and proximal phalanges, sewn to the flexor and extensor tendons, and placed into the stems and hinges of the implants. Each finger was tested intact, and after MCP joint replacement with 3 implants (Swanson [Wright Medical, Memphis, TN], Avanta [Avanta Orthopaedics, San Diego, CA], and NeuFlex [DePuy Orthopaedics, Warsaw, IN]). The fingers were secured to the test fixture and the flexor digitorum profundus flexor and extensor tendons were loaded with physiologic weights. Lateral radiographs were taken at approximately 10 degrees intervals and were digitized on a high-resolution scanner. Instantaneous center of rotation (ICR), tendon excursion, and tendon moment arm were calculated. Statistical analysis was performed using repeated measures one-way analysis of variance and Dunnett post tests.
The ICRs of the intact and implanted MCPs did not follow a smooth path. The variability of the ICRs of the intact MCP joints was 2.1 +/- 0.8 mm. The variations in the Avanta and DePuy implants were similar (3.1 +/- 1.0 mm and 3.5 +/- 1.5 mm, respectively), whereas the Swanson implant was higher (4.9 +/- 1.7 mm). Implant pistoning was most pronounced with the Swanson implant, which moved 2.40 +/- 0.97 mm over the full range of motion. The Avanta and DePuy implants pistoned significantly less than the Swanson implant (1.05 +/- 0.45 mm and 0.69 +/- 0.31 mm, respectively). Flexor tendon excursion was greater for the intact joint when compared with all 3 implants while extensor tendon excursion was similar for all. Flexor tendon moment arm was similar for the intact joint and the Avanta and NeuFlex implants whereas the Swanson implant was reduced significantly; extensor tendon moment arms were similar for all.
The ICR of the NeuFlex implant most closely matched that of the intact MCP joint. The Swanson implant had greater pistoning and dorsal-volar translation when compared with the intact joint and the Avanta and NeuFlex implants. The block-hinge type design of the Avanta and NeuFlex implants improved tendon moment arm overall when compared with the Swanson, likely imparting greater functional ability for finger motion. Overall the NeuFlex implant most closely matched the ICR, tendon excursion, and moment arm when compared with the intact native MCP joint.
本研究旨在比较使用3种市售硅胶植入物进行关节置换术后掌指（MCP）关节的力学情况，并确定关节置换术后的力学与完整关节的力学相比如何。
使用数字化X线片对从5具新鲜冷冻人体尸体上获取的10根离体手指进行平面二维运动学分析。不透X线的标记物被固定在掌骨和近节指骨上，缝在屈肌腱和伸肌腱上，并放置在植入物的柄部和铰链中。每根手指先进行完整测试，然后用3种植入物（斯旺森[赖特医疗公司，田纳西州孟菲斯]、阿万塔[阿万塔骨科公司，加利福尼亚州圣地亚哥]和纽弗莱克斯[迪普伊骨科公司，印第安纳州华沙]）进行MCP关节置换后再测试。手指被固定在测试夹具上，指深屈肌和伸肌腱加载生理重量。以大约10度的间隔拍摄侧位X线片，并在高分辨率扫描仪上进行数字化处理。计算瞬时旋转中心（ICR）、肌腱偏移和肌腱力臂。使用重复测量单因素方差分析和邓尼特事后检验进行统计分析。
完整和植入MCP关节的ICR均未遵循平滑路径。完整MCP关节ICR的变异性为2.1±0.8毫米。阿万塔和迪普伊植入物的变化相似（分别为3.1±1.0毫米和3.5±1.5毫米），而斯旺森植入物的变异性更高（4.9±1.7毫米）。斯旺森植入物的植入物活塞运动最为明显，在整个运动范围内移动了2.40±0.97毫米。阿万塔和迪普伊植入物的活塞运动明显少于斯旺森植入物（分别为1.05±0.45毫米和0.69±0.31毫米）。与所有3种植入物相比，完整关节的屈肌腱偏移更大，而伸肌腱偏移在所有情况下相似。完整关节以及阿万塔和纽弗莱克斯植入物的屈肌腱力臂相似，而斯旺森植入物的屈肌腱力臂显著减小；所有情况下伸肌腱力臂相似。
纽弗莱克斯植入物的ICR与完整MCP关节的ICR最接近。与完整关节以及阿万塔和纽弗莱克斯植入物相比，斯旺森植入物有更大的活塞运动和背 - 掌侧平移。与斯旺森植入物相比，阿万塔和纽弗莱克斯植入物的块状铰链式设计总体上改善了肌腱力臂，可能赋予手指运动更大的功能能力。总体而言，与完整的天然MCP关节相比，纽弗莱克斯植入物在ICR、肌腱偏移和力臂方面最接近。
