Osteochondral allografting in the knee

Chapter synopsis

This chapter summarizes the indications for, techniques to perform, and results of osteochondral allograft (OCA) transplantation for the treatment of symptomatic cartilage defects of the knee.

Important points

• OCA is indicated for symptomatic, full-thickness chondral or osteochondral defects of the femur, tibia, or patella.

• The dowel technique is most commonly used. The shell or small fragment technique is useful for complex or large, relatively inaccessible lesions such as the tibial plateau or posterior femoral condyles.

Clinical/surgical pearls

• Ensure the graft has been received in acceptable condition and the size and laterality are appropriate before the patient is anesthetized.

• A positioning device can be helpful to stabilize the extremity during surgery; this is particularly helpful for very posterior lesions.

• Inspect the graft to determine the largest size graft(s) you can harvest prior to preparing the recipient site.

• Most grafts should be only 5–8 mm thick (bone and cartilage combined).

• Consider bone grafting cysts or deeper lesion with autograft obtained from recipient site preparation.

• Perpendicularity to the site of repair and graft harvest is key to proper fit.

• Different surgical instruments have different tightness of fit designs. Dilate the recipient site and bevel graft edges to minimize force required to seat the graft.

Clinical/surgical pitfalls

• Do not allow graft to dry out during the surgical procedure.

• Prior to insertion, lavage the graft to remove marrow elements.

• Avoid excessive force while seating the graft to prevent chondrocyte death.

• Grafts most commonly fail through the bone, not the cartilage.

• Avoid excessive impact activities during the initial 4 months. The subchondral bone is only slowly substituted and is at its weakest several months after the operation.