Scientific Background: Adult articular cartilage, critical to proper joint function, has minimal self-repair ability. No adequate repair technique exists for large defects.

Cryopreservation which is a process of deep-freezing of cells and tissues, enables the preservation of a high proportion of cells when the tissue is thawed and implanted.

Aim: To evaluate a novel method for cryopreservation of articular cartilage in the form of osteochondral sheep cylinders.

Materials and Methods: Osteochondral cylinders, 9mm diameter x 15mm length, were drilled from fresh cadaver sheep knee condyles. A bank of harvested cryo-preserved osteochondral cylinders was created. 17 sheep were used for transplantation. The thawed cylinders (allografts) were transplanted into the medial femoral condyle of the knee while the lateral femoral condyle received the fresh cylinder autograft as a control. The sheep were followed up for one year, following which in-vitro studies were performed to assess for articular cartilage viability.

Results: Clinically, histologically and radiologically there was almost 100% incorporation of allogenic osteochondral cylinders involving most of the weight-bearing area of the sheep knees.

Conclusion: Osteochondral cylinders can be successfully frozen and then transplanted into sheep knees with regeneration of knee function. Successful cryopreservation of human cartilage will be a major breakthrough in the treatment of cartilage lesions.