Histologic analysis of tissue after failed cartilage repair procedures

This study evaluated the composition of reparative tissue retrieved during revision surgery from full thickness chondral defects in 18 patients in whom abrasion arthroplasty (n = 12), grafting of perichondrial flaps (n = 4), and periosteal patching augmented by autologous chondrocyte implantation in cell suspension (n = 6) failed to provide lasting relief of symptoms. The defects were graded by gross appearance, and all of the tissue filling the defect was retrieved. Histologic evaluation included histomorphometric analysis of the percentage of selected tissue types in cross sections. Immunohistochemistry was performed using antibodies to Types I, II, and X collagen. The histologic appearance of material retrieved after abrasion arthroplasty was that of fibrous, spongiform tissue comprising Type I collagen in 22% +/- 9% (mean +/- standard error of the mean) of the cross sectional area, and degenerating hyaline tissue (30% +/- 10%) and fibrocartilage (28% +/- 7%) with positive Type II collagen staining. Three of four specimens obtained after implantation of perichondrium failed as a result of bone formation that was found in 19% +/- 6% of the cross sectional area, including areas staining positive for Type X collagen, as an indicator for hypertrophic chondrocytes, Revision after autologous chondrocyte implantation was associated with partial displacement of the periosteal graft from the defect site because of insufficient ongrowth or early suture failure. When the graft edge displaced, repair tissue was fibrous (55% +/- 11%), whereas graft tissue attached to subchondral bone displayed hyaline tissue (to 6%) and fibrocartilage (to 12%) comprising Type II collagen at 3 months after surgery. Evaluation of retrieved repair tissue after selected cartilage repair procedures revealed distinctive histologic features reflecting the mechanisms of failure.