HEALING OF LIGAMENTS AND TENDONS

Regeneration of ligaments and tendons is a slow process, compared with the healing of other connective tissues (e.g., bone). Healing starts from the surrounding soft tissues (''extrinsic healing''), but also fr om the ligament or tendon itself (''intrinsic healing''). Regeneration is poor when there is little surrounding soft tissue available, as is the case in the anterior cruciate ligament. Regeneration of the media l collateral ligament of the knee is examined best. Mechanical and ult rastructural properties are not completely normal even 1 year after di ssection of the ligament irrespective of whether it was sutured or not . Our own experiments on rabbit anterior cruciate ligaments showed tha t there is no regeneration after complete transection of the ligament. After incomplete transection there is regeneration, but maximum load of the ligament reaches only about 3/4 of the values of the sham-opera ted contralateral side. An additional experiment showed that regenerat ion is significantly better with the application of continuous passive motion, and elongation of the ligament can be avoided. If the healing tissue is not loaded, regeneration results in unstructured scar tissu e. Under functional load, the collagen fibers are oriented in a longit udinal direction and the mechanical properties are optimized. There ar e no fundamental differences in the healing process between tendons an d ligaments.