Histological and immunohistochemical analysis data for biopsies obtained before or after 18 months post implantation. Data obtained from histological and immunohistochemical analyses of the biopsies were divided into two groups: biopsies taken before (n = 59) or after (n = 11) the cutoff point of 18 months post Hyalograft® C Autograft implantation. Only 23.7% of specimens (n = 59) obtained from patients before 18 months showed characteristics of hyaline cartilage, whereas 45.4% of specimens (n = 11) taken after more than 18 months were of hyaline cartilage. Fibrocartilage was present in 55.9% of biopsies taken before 18 months and in 27.3% of those taken after more than 18 months. Similarly, mixed tissue was present in 20.3% of biopsies taken before 18 months and in 27.3% of those taken after more than 18 months.