Healing of experimental ligament rupture: findings by scanning electron microscopy.

The medial collateral ligaments of the knee joints of 16 rats were cut. Sixteen ligaments were allowed to heal spontaneously while the others were immediately sutured under the microscope. Four sham-operated immobilized rats served as controls. The ligamentous healing was registered after 4-5 weeks of immobilization under a scanning electron microscope (SEM). In the control ligaments, collagen bundles of variable thickness were observed as the main supporting elements. Numerous thin fibers were seen between the bundles. The surgically corrected ligaments showed a microstructural picture often difficult to distinguish from the controls. The unsutured ligaments, however, showed a much more variable picture. In some unsutured cases ligamentous regeneration was blocked by extensive scar formation. In many unsutured cases, however, signs of ligamentous regeneration were observed. It was noted that the SEM is a useful and sophisticated tool for studies on ligament healing.