Prosthetic materials for anterior cruciate ligament reconstruction

Reconstruction of the anterior cruciate ligament (ACL)-deficient knee has been a major focus in sportsmedicine research over the past 20 years. The need for functional stability for patients with symptomatic instability, especially if they participate in pivoting or jumping sports, as well as the potential for development of precocious arthritis in the ACL-deficient knee, has led to the use of intra-articular autogenous reconstruction from multiple tissue sources. The most popular method of reconstruction involves the central one third of the patellar tendon with attached bone blocks from the patella and tibial tubercle; this remains the "gold standard" to which other reconstructions are compared. Other common tissue sources are the semi-tendinosus, gracilis, and fascia lata, utilized in a number of varied techniques. Although the initial strength of these various autografts has been more than adequate to withstand the stresses of various activities, autogenous tissue transplants undergo degeneration in a hostile synovial environment. Butler et al have shown that the original strength of patellar tendon grafts in primates declines approximately 15% within six weeks. The original strength sometimes fails to fully return, and there seems to be great variability in healing and revascularization of autogenous tissue. Furthermore, autogenous transplants require the sacrifice of a tendon or ligament with a biologic function. In other instances, autogenous tissue may not be available or easily sacrificed, most commonly secondary to a previous autogenous reconstruction that has failed. Over the last decade, there have consequently been extensive laboratory studies as well as clinical trials of various prosthetic materials.