To investigate (1) The relationship between macroscopic grading and durability of cartilage repair following collagen-covered autologous chondrocyte implantation (ACI-C) in the knee; (2) The influence of histology on durability of cartilage repair; (3) The relationship between macroscopic appearance and histology of repair tissue. The modified Cincinnati scores (MCRS) of eighty-six patients were evaluated prospectively at one year and at the latest follow-up (mean follow-up = 4.7yrs. Range = 4 to 7 years). Needle biopsies of their cartilage repair site were stained with Haematoxylin and Eosin and some with Safranin O and the neo-cartilage was graded as hyaline-like (n=32, 37.2%), mixed fibro-hyaline (n=19, 22%) and fibro-cartilagenous tissue (n=35, 40.7%). Macroscopic grading of the repair tissue using the international cartilage repair society grading system (ICRS) was available for fifty-six patients in the study cohort. Statistical analyses were performed to investigate the significance of histology and ICRS grading on MCRS at 1 year and at the latest follow-up.Aims
Patients and methods
The mean clinical follow-up was 39.4 months (13mths to 8 years) and the mean timing of biopsy was 14.8 months. The mean age at the time of surgery was 32 years (15 to 55 years). The site of defect was as follows: medial femoral condyle-95, lateral femoral condyle-25, trochlea-7, patella 27 and multiple sites- 12. The mean proportion of viable cells available for implantation was 96.3 % (range: 86 to 100) and the mean number of multiplication of cells during culture was 90 (range: 9 to 667).
The most favourable sites were lateral femoral condyle and trochlea where as the least favourable site was patella. There was no correlation between the mental score of patients and the final clinical result. Improvement in functional score was significantly higher among those who had a higher pre-operative function (p<
0.001). There were 7 patients who had previously failed micro-fracture and all of them obtained significant improvements in pain and function. Those who had a higher proportion of viable cells after cell culture demonstrated a tendency towards better outcome, but failed to reach statistical significance (p=0.14). There was no correlation between the number of cell multiplications at the time of cell culture and final clinical outcome (p=0.65). There was no significant difference in clinical outcome between the ACI- C and MACI techniques of ACI (p>
0.05).