Meunier Matthew J, Hentzen Eric, Ryan Michael, Shin Alexander Y, Lieber Richard L
Department of Orthopedic Surgery, University of California, San Diego and Veterans Administration Medical Centers, San Diego, CA 92103-8894, USA.
J Hand Surg Am. 2004 Jul;29(4):689-93. doi: 10.1016/j.jhsa.2004.03.002.
Metacarpal fractures are common in hand surgery. Metacarpal shortening ranging from 2 mm to as much as 10 mm has been deemed acceptable in the literature. We examined the effect of metacarpal shortening on interosseous muscle architecture and predicted force production capacity based on the standard muscle length-tension curve (commonly known as the Blix curve).
The dorsal interosseous muscles between the middle and ring finger metacarpals from 9 adult human cadaver hands were exposed and studied. The ring finger metacarpal was translated proximally in 2-mm increments in relation to a stationary middle finger metacarpal. Digital images were obtained and analyzed to define the length and orientation of individual muscle fibers with each incremental change in position.
Interosseous muscle fiber length increased and pennation angle decreased uniformly with increasing proximal translation of the ring finger metacarpal. At 10 mm of shortening the fiber length had increased to 20.8 +/- 1.8 mm, or to approximately 125% of optimum fiber length, and the pennation angle had decreased to 6.7 degrees +/- 2.2 degrees or by approximately 50%.
The interosseous muscles have been shown to have a high fiber-to-muscle length ratio. This ratio indicates that these muscles function optimally over a short range of lengths, leaving them vulnerable to derangement in function owing to alteration in the surrounding bony architecture. Based on the standard muscle length--tension relationship we had predicted a steady linear decrease in interosseous power with proximal translation of the metacarpal. The results indicate an initial linear progression with a plateau at approximately 8 mm of shortening. At 2 mm of shortening there is an approximately 8% loss of power generation, at 10 mm of metacarpal shortening we predict the interosseous muscle to be capable of only approximately 55% of its optimum power compared with the resting position.
掌骨骨折在手部外科手术中很常见。文献中认为掌骨缩短2毫米至多达10毫米是可以接受的。我们研究了掌骨缩短对骨间肌结构的影响，并根据标准肌肉长度 - 张力曲线（通常称为布利克斯曲线）预测力产生能力。
暴露并研究来自9具成年人体尸体手部的中指和环指掌骨之间的背侧骨间肌。相对于固定的中指掌骨，将环指掌骨向近端以2毫米的增量平移。获取并分析数字图像，以确定随着位置的每次增量变化，单个肌纤维的长度和方向。
随着环指掌骨向近端平移增加，骨间肌纤维长度增加，羽状角均匀减小。在缩短10毫米时，纤维长度增加到20.8±1.8毫米，或约为最佳纤维长度的125％，羽状角减小到6.7度±2.2度，或约减小50％。
已证明骨间肌具有高纤维与肌肉长度比。该比例表明这些肌肉在短长度范围内功能最佳，使其容易因周围骨结构的改变而功能紊乱。基于标准肌肉长度 - 张力关系，我们预测随着掌骨向近端平移，骨间肌力量会稳定线性下降。结果表明最初呈线性进展，在缩短约8毫米时出现平台期。在缩短2毫米时，发电能力损失约8％，在掌骨缩短10毫米时，我们预测骨间肌与静止位置相比仅能产生约其最佳力量的55％。
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