Proprioception in the anterior cruciate ligament of the human knee joint--morphological bases. A light, scanning and transmission electron microscopy study]

In 21 human anterior cruciate ligaments removed with their synovial sheaths during autopsy and operation, nerves and nerve endings were demonstrated by light microscopy, scanning electron microscopy and transmission electron microscopy. Ultrastructural examination allowed a classification of nerve endings into three types: Ruffinian corpuscles, Pacinian corpuscles and free (afferent and efferent) nerve endings. The nerve endings corresponded to those characteristic of articular capsules. The anterior cruciate ligament shows evidence of a proprioceptive function besides its stabilizing function, which is based on its collagenous structure. Together, they probably represent the most important factor in the dynamic stabilization of the knee joint. At present it is only possible to speculate on the potential clinical significance of these findings, for example in development of rehabilitation programs and prevention strategies offering protection against anterior cruciate tears. This also applies to the question of whether to preserve the ligament during surgery for ruptures and knee-joint prostheses.