Background: New methods have been used, with promising results, to
treat full-thickness cartilage defects. The objective of the present study was
to compare autologous chondrocyte implantation with microfracture in a
randomized trial. We are not aware of any previous randomized studies
comparing these methods.
Methods: Eighty patients without general osteoarthritis who had a
single symptomatic cartilage defect on the femoral condyle in a stable knee
were treated with autologous chondrocyte implantation or microfracture (forty
in each group). We used the International Cartilage Repair Society, Lysholm,
Short Form-36 (SF-36), and Tegner forms to collect data. An independent
observer performed a follow-up examination at twelve and twenty-four months.
Two years postoperatively, arthroscopy with biopsy for histological evaluation
was carried out. The histological evaluation was done by a pathologist and a
clinical scientist, both of whom were blinded to each patient's treatment.
Results: In general, there were small differences between the two
treatment groups. At two years, both groups had significant clinical
improvement. According to the SF-36 physical component score at two years
postoperatively, the improvement in the microfracture group was significantly
better than that in the autologous chondrocyte implantation group (p = 0.004).
Younger and more active patients did better in both groups. There were two
failures in the autologous chondrocyte implantation group and one in the
microfracture group. No serious complications were reported. Biopsy specimens
were obtained from 84% of the patients, and histological evaluation of repair
tissues showed no significant differences between the two groups. We did not
find any association between the histological quality of the tissue and the
clinical outcome according to the scores on the Lysholm or SF-36 form or the
visual analog scale.
Conclusions: Both methods had acceptable short-term clinical
results. There was no significant difference in macroscopic or histological
results between the two treatment groups and no association between the
histological findings and the clinical outcome at the two-year time-point.
Level of Evidence: Therapeutic study, Level I-1a
(randomized controlled trial [significant difference]). See Instructions to
Authors for a complete description of levels of evidence.