Morphological characteristics of angiogenesis in the myofascial tissues of a limb elongated by the Ilizarov method.

We studied the effects of limb elongation upon the myofascial structures of 27 dogs, utilizing angiography, light microscopy, transmission and scanning electron microscopy, and stereologic analysis to ascertain the angiogenic effects of distraction upon soft tissues subjected to hind limb elongation. Angiography demonstrated the development of an extensive vascular network within the tibialis anterior, gastrocnemius, and extensor hallucis longus muscles in the elongated leg. Using the normal contralateral limb as a control, it is demonstrated that limb elongation results in an increase in the density of microvascular structures, as well as an increase in the volume and surface area of the vascular walls. During elongation, there occurs a growth of vascular bands into the central parts of the tendon of the tibialis anterior muscle from the paratenon and peritendineum through the connective tissue layers of the endotendineum. Angiogenesis within the tendon was observed throughout the period of distraction through the second month of elongation. Angiogenesis in the fascia in the tibialis anterior muscle takes place via the formation of growth buds from pre-existing microvessels. At the end of the first month of distraction, microvascular polymorphism reaches its maximum, as does the number of provisional microvessels within the fascia. For the most part, the newly formed microvessels are brought along to specific differentiation by the end of the second month of distraction.