Periosteal autologous chondrocyte implantation for patellar chondral defect in patients with normal and abnormal patellar tracking.

Reported results for patellar ACI include a mixed population of patients having or not a concomitant correction of the extensor mechanism. No study has reported separate outcome for those two patellar ACI subgroups. Forty four patients were included in this study designed to compare the outcome of patellar ACI with extensor realignment (group A) to patellar ACI with normal patellofemoral tracking (group B). Group A (n=22) had a higher increase in average modified Cincinnati knee score (4.5 vs. 1.7 points), better function (1.7 vs. 2.5), better SF-36 physical component scores (70.9 vs. 55.4 points) and higher IKDC scores (85.2 vs. 60.6 points) when compared to group B (n=22) at an average follow-up of 2 years. Patellar ACI with concomitant extensor realignment has superior outcome than patellar ACI with normal patellofemoral tracking. An unloading osteotomy could be desirable in selected patients with normal patellofemoral biomechanics to improve the outcome in this population.

Prospective clinical study of autologous chondrocyte implantation and correlation with MRI at three and 12 months.

In order to determine the usefulness of MRI in assessing autologous chondrocyte implantation (ACI) the first 57 patients (81 chondral lesions) with a 12-month review were evaluated clinically and with specialised MRI at three and 12 months. Improvement 12 months after operation was found subjectively (37.6 to 51.9) and in knee function levels (from 85% International Cartilage Repair Society (ICRS) III/IV to 61% I/II). The International Knee Documentation Committee (IKDC) scores showed an initial deterioration at three months (56% IKDC A/B) but marked improvement at 12 months (88% A/B). The MRI at three months showed 82% of patients with at least 50% defect fill, 59% with a normal or nearly normal signal at repair sites, 71% with a mild or no effusion and 80% with a mild or no underlying bone-marrow oedema. These improved at 12 months to 93%, 93%, 94% and 91%, respectively. The overall MR score at 12 months suggested production of normal or nearly normal cartilage in 82%, corresponding to a subjective improvement in 81% of patients and 88% IKDC A/B scores. Second-look surgery and biopsies in 15 patients (22 lesions) showed a moderate correlation of MRI with visual scoring; 70% of biopsies showed hyaline and hyaline-like cartilage. Thus, MRI at 12 months is a reasonable non-invasive means of assessment of ACI.