Regeneration of articular cartilage of the knee.

Cartilage therapy for focal articular lesions of the knee has been implemented for more than a decade, and it is becoming increasingly available. What do we know on the healing response of cartilage lesions? What do we know on the treatment of focal cartilage lesions of the knee and the prognostic factors involved? PubMed articles related to articular cartilage regeneration of the knee in clinical studies were searched from January 2006 to November 2012, using the following key words: articular cartilage, regeneration, clinical studies, and knee. A total of 44 reports were found. They showed the following possibilities for the treatment of focal lesions of the articular cartilage of the knee: cartilage regeneration and repair including cartilage reparation with gene-activated matrices, autologous chondrocyte implantation (ACI) and matrix-induced ACI (MACI), microfracture, osteochondral autograft transfer (mosaicplasty), biological approaches (scaffolds, mesenchymal stem cells-MSCs, platelet-rich plasma, growing factors-GF, bone morphogenetic proteins-BMPs, magnetically labeled synovium-derived cells-M-SDCs, and elastic-like polypeptide gels), osteotomies, stem-cell-coated titanium implants, and chondroprotection with pulsed electromagnetic fields. Untreated cartilage lesions on the femoral condyles had a superior healing response compared to those on the tibial plateaus, and in the patellofemoral joint. Clinical outcome regarding the treatment of medial defects is better than that of the lateral defects. Improvement from baseline was better for patients < or = 30 years compared with patients > or = 30 years. ACI, MACI, and mosaicplasty have shown similar results. The results of comparative clinical studies using ACI have shown some superiority over conventional microfracturing in medium or large defects and in long-term durability. Some biological methods such as scaffolds, MSCs, GF, M-SDCs, BMPs, and elastic-like polypeptide gels still need more research.