Background: Matrix-associated autologous chondrocyte implantation (MACI) has been recently used to treat cartilage defects. The investigators had previously developed a biphasic osteochondral composite as the construct for chondrocyte implantation. The investigators further conducted this feasibility study of such device to treat patients with osteochondral lesion of the knee joints.

Methods: Ten patients with symptomatic isolated osteochondritis at the femoral condyle were treated by replacing the pathological tissue with autologous chondrocyte-laden biphasic cylindrical plug of DL-poly-lactide-co-glycolide, with its lower body impregnated with -tricalcium phosphate as the osseous phase. The osteochondral lesion was drilled to fashion a pit of identical size and shape as the plug. The chondrocyte-laden plug was press-fit to fill the pit. Outcome of repair was examined by KOOS scale at 3, 6 and 12 months postoperatively, and tissue sample was collected with second-look arthroscopic needle-biopsy at 12 months. The primary outcome parameter was the postoperative change of KOOS; and the secondary outcome parameter was the regeneration of cancellous bone and hyaline cartilage at the repair site.

Inclusion Criteria:

• Age: 18 ~ 60 years
• Articular cartilage defect of the knee
• Diagnosis by X-ray and/or MRI, Arthroscopy
• Confined area: diameter < 3 cm
• Full layer cartilage damage

Exclusion Criteria:

• Pregnancy
• Nonunion of fracture around the knee
• Diffuse degenerative arthropathy of the knee
• Diffuse cartilage pathology due to
• Rheumatism: rheumatoid, psoriatic, …
• Metabolic disorder: gouty, hemorrhagic, …
• Stiff knee from any reason
• Flexion < 130˚
• Extension loss > 20˚