Yucesoy Can A, Koopman Bart H F J M, Grootenboer Henk J, Huijing Peter A
Biomedical Engineering Institute, Boğaziçi University, Bebek, Istanbul, Turkey.
Biomech Model Mechanobiol. 2008 Jun;7(3):175-89. doi: 10.1007/s10237-007-0084-z. Epub 2007 May 8.
Effects of extramuscular myofascial force transmission on the acute effects of aponeurotomy were studied using finite element modeling and implications of such effects on surgery were discussed. Aponeurotomized EDL muscle of the rat was modeled in two conditions: (1) fully isolated (2) with intact extramuscular connections. The specific goal was to assess the alterations in muscle length-force characteristics in relation to sarcomere length distributions and to investigate how the mechanical mechanism of the intervention is affected if the muscle is not isolated. Major effects of extramuscular myofascial force transmission were shown on muscle length-force characteristics. In contrast to the identical proximal and distal forces of the aponeurotomized isolated muscle, substantial proximo-distal force differences were shown for aponeurotomized muscle with extramuscular connections (for all muscle lengths F (dist) > F (prox) after distal muscle lengthening). Proximal optimal length did not change whereas distal optimal length was lower (by 0.5 mm). The optimal forces of the aponeurotomized muscle with extramuscular connections exerted at both proximal and distal tendons were lower than that of isolated muscle (by 15 and 7%, respectively). The length of the gap separating the two cut ends of the intervened aponeurosis decreases substantially due to extramuscular myofascial force transmission. The amplitude of the difference in gap length was muscle length dependent (maximally 11.6% of the gap length of the extramuscularly connected muscle). Extramuscular myofascial force transmission has substantial effects on distributions of lengths of sarcomeres within the muscle fiber populations distal and proximal to the location of intervention: (a) Within the distal population, the substantial sarcomere shortening at the proximal ends of muscle fibers due to the intervention remained unaffected however, extramuscular myofascial force transmission caused a more pronounced serial distribution towards the distal ends of muscle fibers. (b) In contrast, extramuscular myofascial force transmission limits the serial distribution of sarcomere lengths shown for the aponeurotomized isolated muscle in the proximal population. Fiber stress distributions showed that extramuscular myofascial force transmission causes most sarcomeres within the aponeurotomized muscle to attain lengths favorable for higher force exertion. It is concluded that acute effects of aponeurotomy on muscular mechanics are affected greatly by extramuscular myofascial force transmission. Such effects have important implications for the outcome of surgery performed to improve impeded function since muscle in vivo is not isolated both anatomically and mechanically.
利用有限元模型研究了肌外肌筋膜力传递对腱膜切开术急性效应的影响，并讨论了这些效应在手术中的意义。将大鼠的腱膜切开的趾长伸肌（EDL）在两种情况下进行建模：（1）完全分离；（2）保留完整的肌外连接。具体目标是评估与肌节长度分布相关的肌肉长度 - 力特性的变化，并研究如果肌肉未被分离，干预的力学机制会受到怎样的影响。结果表明，肌外肌筋膜力传递对肌肉长度 - 力特性有显著影响。与腱膜切开的分离肌肉相同的近端和远端力不同，保留肌外连接的腱膜切开肌肉显示出明显的近端 - 远端力差异（在远端肌肉拉长后，对于所有肌肉长度，F（远端）> F（近端））。近端最佳长度没有变化，而远端最佳长度更低（低0.5毫米）。保留肌外连接的腱膜切开肌肉在近端和远端肌腱处施加的最佳力均低于分离肌肉（分别低15%和7%）。由于肌外肌筋膜力传递，被干预腱膜的两个切断端之间的间隙长度大幅减小。间隙长度差异的幅度取决于肌肉长度（最大为保留肌外连接肌肉间隙长度的11.6%）。肌外肌筋膜力传递对干预部位近端和远端肌纤维群体内肌节长度的分布有显著影响：（a）在远端群体中，由于干预导致的肌纤维近端肌节的显著缩短不受影响，然而，肌外肌筋膜力传递导致向肌纤维远端更明显的串联分布。（b）相反，肌外肌筋膜力传递限制了腱膜切开的分离肌肉在近端群体中显示的肌节长度的串联分布。纤维应力分布表明，肌外肌筋膜力传递使腱膜切开肌肉内的大多数肌节达到有利于更高力施加的长度。得出的结论是，腱膜切开术对肌肉力学的急性效应受肌外肌筋膜力传递的影响很大。这些效应对于旨在改善功能障碍的手术结果具有重要意义，因为体内的肌肉在解剖学和力学上都不是孤立的。
