Purpose: To define the role of ACI in treatment of cartilage defects in the knee joint.

Method: 106 articular cartilage defects in 79 knees of 77 patients were treated by ACI as described by Brittberg et al, 1994. 43.5% of the lesions involved the patella, 35.2% the femoral condyles, 16.7% the trochlea, and 4.6% the tibial condyles. 20% of knees had more than one defect. Associated biomechanical procedures were carried out in 88.7%.

Results: 70 lesions in 58 knees and 56 patients were assessed arthroscopically 9 months after implantation; 4 eligible patients were not assessed. The average ICRS repair score (maximum 12) was as follows: tibial condyle 11.5, (4 defects); patella 11.3, (32 defects); femoral condyle 11.0, (23 defects) and trochlea 10.7, (11 defects). Synovitis was markedly reduced in all knees with well healed defects. Contraindications to ACI in this series were:

Non-contained defects,

Bi-polar lesions,

Patients greater than 45 years,

Uncorrected biomechanics,

Regional pain syndrome type 1,

Limited joint movement,

Defective subchondral bone plate.

Conclusion: ACI effectively repairs articular cartilage defects in the knee joint, provided that the contraindications are recognised. Unlike other series, the results for the patella, patellofemoral joint have matched those for the femoral condyle. This is attributed to the simultaneous biomechanical correction of the patellofemoral joint. Stabilisation of the articular surface results in resolution of synovitis.