DURABILITY OF CARTILAGE REPAIR- DOES HISTOLOGY MATTER?

Abstract

Aim: The aim of this study was to correlate the histology of cartilage repair site with long term clinical function.

Materials and methods: We have analyzed the clinical results of a cohort of patients who had collagen-covered autologous chondrocyte implantations performed since 1998. Our hypothesis was that the hyaline cartilage repair does influence the clinical outcome.

The modified Cincinnati scores (MCRS) of eighty-six patients were evaluated prospectively at one year and at the latest follow-up following ACI-C (mean follow-up= 4.7 years. Range= 4 to 7 years). All these patients underwent biopsies of their cartilage repair site performed at variable periods between six months and five years following ACI-C (mean=22.2 months). The neo-cartilage was graded as hyaline (n=32), mixed fibrohyaline (n=19), fibrocartilagenous (n=35) and fibrous (n=0).

Results: The clinical results showed that at one year, the percentage of patients with excellent and good results was 84.4, 89.5 and 74.3 respectively for those with hyaline, mixed fibro-hyaline and fibro-cartilagenous histology respectively. Their mean MCRS were 70.8, 72.4 and 66.2 respectively. This difference was not statistically significant (p=0.34).

However, their clinical scores at the latest follow-up demonstrated a significantly superior result for those with hyaline repair tissue when compared to those with mixed fibro-hyaline and fibro-cartilagenous repair tissue (p=0.05). The percentage of patients with excellent and good results for those with hyaline, mixed fibro-hyaline and fibro-cartilagenous repair was 75, 42 and 68.6 respectively. Their mean MCRS were 70.6, 56.8 and 63.9 respectively.

Conclusion: This study demonstrates that any form of cartilage repair would give good clinical outcome at one year. At four years and beyond, it appears that patients with hyaline repair tissue tend to show a more favourable clinical outcome whereas those who demonstrated mixed fibrohyaline and fibrocartilagenous repair would show less favourable clinical results.