Evaluation of donor site intrinsic healing response in autologous osteochondral grafting of the knee.

We report the case of a 45-year-old male patient who underwent autologous osteochondral autografting in the knee for osteochondritis dissecans. The patient required revision surgery 1 year postoperatively, which allowed histologic and mechanical characterization of the intrinsic healing response of the initial graft donor sites. Histologic examination showed heterogeneous areas of dense fibrous tissue, bone, and discrete areas of cartilage. Mechanical testing using a confined compression testing technique determined the equilibrium stiffness as 0.97 MPa. The majority of dense fibrous tissue and areas of bone are likely responsible for the observed increased stiffness. When performing osteochondral autografting, consideration must be given to the benefit afforded to improving the areas of cartilage injury with the potential morbidity associated with graft harvest at the donor sites.