Histopathological examination in evaluation of long-term results after osteocartilaginous transplantation.

OBJECTIVE To assess long-term outcomes of osteocartilaginous transplantation for non-degenerative lesions of hyaline articular cartilage in the knee, by performing minibiopsies from the transplanted area and examining them histopathologically. PATIENTS AND METHODS Forty-four patients with post-traumatic cartilage injuries of the bearing surfaces of the knee were enrolled in a prospective study, that included treatment with autologous osteocartilaginous grafts at the level of the lesion, "second look" arthroscopy and targeted minibiopsies at one year and five years postoperatively (six minibiopsies per patient). The collected tissue fragments were examined by optic microscopy. In order to integrate the histopathological findings in the clinical context, the function of the knee was also quantified by calculation of the International Cartilage Repair Society Score preoperatively, at one year and at five years postoperatively. RESULTS Five years post-transplant the outcomes for 36 patients were available. One year post-transplant, the histopathological examination revealed the presence of hyaline cartilage in 165 of the 216 (76.39%) tissue samples collected and fibrocartilage in 51 (23.61%) respectively. Five years after surgery, the proportions of these findings were 159/216 (73.61%) for hyaline cartilage and 57/216 (26.39%) for fibrocartilage. The difference was not statistically significant (p>0.1).The evolution of the ICRS clinical score was from 38.57±3.42 preoperatively to 80.31±3.85 (p<0.0001) after one year and to 81.35±4.57, respectively at five years after surgery. CONCLUSIONS Autologous osteocartilaginous transplantation brings hyaline articular cartilage at the level of the injured area. Approximately three quarters of the surface lesion remains covered by high quality hyaline cartilage that maintains its macroscopic structure and architecture for a long period of time.