Tendon the presence of denatured collagen are factors that are believed to cause weakening of the tendon ECM and an increase in the potential for another rupture to occur. In response to repeated mechanical loading or injury, cytokines may be released by tenocytes and can induce the release of MMPs, causing degradation of the ECM and leading to recurring injury and chronic tendinopathies. A variety of other molecules are involved in tendon repair and regeneration. There are five growth factors that have been shown to be significantly upregulated and active during tendon healing: insulin-like growth factor 1 (IGF-I), platelet-derived growth factor
Tendon transfer or positional transfers. Power transfers are done to perform motion, and therefore requires relatively more powerful donor muscles. Positional transfers, on the other hand, do not require powerful donors. The strength of the antagonist muscle should be similar to the donor to avoid overcorrection and to maintain correct posture. Tendon excursion, or distance a tendon travels upon movement, should be similar to that of the recipient to adequately restore the function. Any transfer of a tendon for another function will generally lose one grade of power. For example, M4 muscle power grade will become M3. A single tendon should be