Indiana Hand to Shoulder Center, Indianapolis, IN.
Indiana Hand to Shoulder Center, Indianapolis, IN.
J Hand Surg Am. 2024 Sep;49(9):932.e1-932.e7. doi: 10.1016/j.jhsa.2022.11.018. Epub 2023 Feb 23.
The purpose of our study was to investigate, in a cadaver model, the effect of increasing thumb metacarpophalangeal (MCP) joint hyperextension on thumb axial load and key pinch force after thumb trapeziectomy and flexor carpi radialis suspensionplasty. We developed a cadaveric model to test whether thumb MCP joint hyperextension after trapeziectomy would have a negative effect on key pinch force and increase loads across a reconstructed thumb carpometacarpal (CMC) joint.
We created a cadaveric biomechanical model that varied thumb MCP joint hyperextension while measuring thumb CMC axial and key pinch force under standardized loads. Direct observations were made of how key pinch and axial thumb CMC force change with increasing thumb MCP joint hyperextension. We measured the thumb key pinch force and axial thumb CMC joint load with the thumb MCP joint in 0°, 10°, 20°, 30°, 40°, 50°, and 60° of hyperextension.
There was a 0.88 N (2.4%) increase in axial force across the thumb CMC per every 10° of increasing thumb MCP joint hyperextension. We found a 0.53 N (4.4%) reduction in key pinch force for every 10° of increasing thumb MCP joint hyperextension. Therefore, at 60° of thumb MCP joint hyperextension, the axial force across the thumb CMC increased by 5.3 N (14.6%) and the key pinch force was weakened by 3.2 N (26.6%).
With progressive thumb MCP joint hyperextension after thumb CMC arthroplasty, we found a decrease in key pinch force and an increase in axial thumb CMC joint force. The decrease in key pinch force was larger than the relatively small increase in thumb CMC force.
This study helps elucidate the biomechanics of the thumb CMC joint after resection arthroplasty with thumb MCP joint hyperextension and helps understand the interplay between these 2 conditions.
本研究旨在通过尸体模型探讨拇指掌指（MCP）关节过伸对拇指 trapeziectomy 和 flexor carpi radialis suspensionplasty 后拇指轴向负荷和关键捏力的影响。我们建立了一个尸体模型，以测试拇指 MCP 关节过伸是否会对关键捏力产生负面影响，并增加重建的拇指腕掌（CMC）关节的负荷。
我们创建了一个尸体生物力学模型，该模型在标准化负荷下改变拇指 MCP 关节过伸程度，同时测量拇指 CMC 的轴向和关键捏力。我们观察了关键捏力和拇指 CMC 轴向力随拇指 MCP 关节过伸的增加而如何变化。我们测量了拇指 MCP 关节在 0°、10°、20°、30°、40°、50°和 60°过伸时的拇指关键捏力和拇指 CMC 关节的轴向力。
拇指 MCP 关节每增加 10°过伸，拇指 CMC 上的轴向力增加 0.88 N（2.4%）。我们发现拇指 MCP 关节每增加 10°过伸，关键捏力减少 0.53 N（4.4%）。因此，拇指 MCP 关节过伸 60°时，拇指 CMC 上的轴向力增加 5.3 N（14.6%），关键捏力减弱 3.2 N（26.6%）。
随着拇指 CMC 关节置换术后拇指 MCP 关节的渐进性过伸，我们发现关键捏力下降，拇指 CMC 关节轴向力增加。关键捏力的下降大于拇指 CMC 力的相对较小增加。
这项研究有助于阐明拇指 CMC 关节切除关节成形术后拇指 MCP 关节过伸的生物力学，并有助于理解这两种情况之间的相互作用。
