**6.4 Surgical and biologic procedures**

Advances in tissue engineering and biologic therapy have led to a few limited successes. Perhaps the most notable is autologous chondrocyte implantation (ACI). Indications


This procedure attempts to repair a symptomatic cartilage defect (Figure 3A) through implantation of chondrocytes grown ex vivo from a small cartilage biopsy sample obtained from the patient in a staging arthroscopy. After debridement of any degenerated tissue in the defect, a patch material, either periosteum from the patient or a synthetic collagen membrane, is sutured over the defect to create a watertight chamber into which the chondrocyte suspension is injected (Figure 3B). The chondrocytes attach to the subchondral bone and produce cartilage matrix, eventually filling the defect with hyalinelike cartilage.

Fig. 5. Total hip replacement
