Use of allografts in knee reconstruction: II. Surgical considerations.

The first allograft used in the knee was articular cartilage. The need to use fresh grafts and the absence of proper instruments for shaping and sizing implants have prevented widespread usage of articular cartilage allografts. Patient selection is very important; young, active, well-motivated individuals with defects smaller than 4 cm2 caused by trauma or osteochondritis dissecans have the best results. Failure is evidenced by crumbling of the supporting bone and fragmentation of the graft, a process identical to that seen in osteonecrosis. The use of allografts to reconstruct knee ligaments has gained wider acceptance. The availability of high-quality tissue from modern tissue banks, excellent preservation methods, a decrease in short-term surgical morbidity, and results at 2- to 5-year follow-up that are essentially equivalent to those obtained with autogenous grafts have combined to make allografts an alternative to using the patient's own tissue. However, long-term stability results are needed for comparison with autogenous grafts. Replacing an unsalvageable meniscus with an allograft is an appealing concept, with the potential for restoring normal load distribution, lubrication, and stability in the knee. Healing of the grafts and pain reduction have been reported by several investigators, but concerns about graft shrinkage, central hypocellularity, and long-term functional survival remain.