Changes in pennate muscle architecture after gradual tibial lengthening in goats

Abstract

The purpose of this investigation was to examine the changes in unipennate muscle architecture after distraction osteogenesis. Nine adult goats underwent 20% tibial lengthening in one of the hind limbs. Immediately after distraction, lengthened and contralateral (untreated) tibialis caudalis (TC) muscles were harvested. Lengths of the muscle belly, muscle fiber (FL), sarcomere (SL), tendon (TL), and superficial aponeurosis, as well as muscle mass, pennation angle (PA), and physiological cross-sectional area (PCSA), were compared between the treated and contralateral sides. Lengthened TC muscle demonstrated 20.8% increase in belly length, 4.39% increase in TL, and 36.7% increase in FL, while PA decreased by 37.2% (P ¼ 008). Muscle length increase was mainly due to lengthening of muscle belly, which resulted both from FL increase and 15.3% length increase in the aponeurosis component of muscle belly, without significant effect of the PA decrease. The FL increase was due to SL increase, not to sarcomere neogenesis, while mass and PCSA did not change. We concluded that although muscle architecture can be adversely affected by distraction because of deficient sarcomere neogenesis, PCSA can remain unchanged, giving false impression of preserved function. Change in PA plays only minimal role in muscle adaptation to distraction. Anat Rec, 290:461-467, 2007Rec, 290:461-467, . 2007 Wiley-Liss, Inc.

Use it or lose it: multiscale skeletal muscle adaptation to mechanical stimuli

“…Increased sarcomere lengths, rather than sarcomere numbers, have been observed in a few studies, indicating that adaptation to the overstretch may have been incomplete or partially unsuccessful [84,85]. Failure of a muscle to properly adapt to the overstretch it experiences may result in contracture, or insufficient muscle length [85].…”

Structure‐function relationships in tendons: a review

“…Limb lengthening by distraction osteotomy has become a routine surgical procedure and studies in goats have shown that it is the muscle rather than the tendon that provides the extra length within the muscle–tendon unit necessary for proper limb function. While the muscle may elongate by almost 10% of its initial length, the tendon only does so by 3–4% (Elsalanty et al. 2007).…”

Les étirements musculo-tendineux : des données scientifiques à une pratique raisonnée

“…Toutes les études ne montrent pas d'augmentation du nombre de sarcomères en série après un programme d'étirement. Certaines d'entre elles ont montré que la longueur des sarcomères pouvait augmenter à la suite de protocoles d'étirement sur modèle animal [49,50]. De tels résultats ont tendance à suggérer que la réponse initiale des muscles aux étirements est l'augmentation de la longueur de sarcomère, mais quand un seuil global d'étirement est atteint, alors de nouveaux sarcomères sont disposés en séries.…”