The effect of anterior cruciate ligament resection and immediate or delayed implantation of a meniscus prosthesis on knee joint biomechanics and cartilage. An experimental study in rabbits.

In a rabbit experiment with anterior cruciate ligament (ACL) resection, immediate substitution of the medial meniscus with a prosthesis was compared with delayed prosthetic implantation after a postmeniscectomy period of three weeks. The knees with a prosthetic implant were compared with their contralateral joints as well as to joints with an intact ACL and menisci. Anterior cruciate ligament resection alone led to disturbed biomechanics and cartilage degeneration. Anterior cruciate ligament resection in combination with meniscus resection increased cartilage degeneration and led to more inferior biomechanics. Ingrowth and stable fixation was less frequent when the prosthesis was inserted three weeks after meniscus resection than when inserted immediately. Furthermore, in knees with delayed prosthetic implantation, only minor improvement in terms of cartilage protection was shown when compared with knees with resection only. In contrast, knees with immediate meniscus replacement demonstrated similar joint stiffness and stress relaxation characteristics and similar cartilage protection effects as knees with a nonresected medial meniscus.