CURRENT CONCEPTS IN THE TREATMENT OF ARTICULAR-CARTILAGE DEFECTS

Over time, articular cartilage loses the capacity to regenerate itself , making repair of articular surfaces difficult. Lavage and debridemen t may offer temporary relief of pain for up to 4.5 years, but offer no prospect of longterm cure. Likewise, marrow-stimulation techniques su ch as drilling, microfracture, or abrasion arthroplasty fail to yield long-term solutions because they typically promote the development of fibrocartilage. Fibrocartilage lacks the durability and many of the me chanical properties of the hyaline cartilage that normally covers arti cular surfaces. Repair tissue resembling hyaline cartilage can be indu ced to fill in articular defects by using perichondrial and periosteal grafts. However, these techniques are limited by the amount of tissue available for grafting and the tendency toward ossification of the re pair tissue. Autogenous osteochondral arthroscopically implanted graft s (mosaicplasty), or open implantation of lateral patellar facet (Oute rbridge technique), requires violation of subchondral bone. Osteochond ral allografts risk viral transmission of disease and low chondrocyte viability, in addition to removal of host bone for implantation. Autol ogous chondrocyte implantation offers the opportunity to achieve biolo gic repair, enabling the surgeon to repair the joint surface with auto logous articular cartilage. With this technique, care must be taken to ensure the safety, viability, and microbial integrity of the autologo us cells while they are expanded in culture over a 4- to 5-week period prior to implantation. Surgical implantation requires equal attention to meticulous technique. In the future, physiologic repair also may b ecome possible using mesenchymal stem cells or chondrocytes delivered surgically in an ex vivo-derived matrix. This would allow in vitro man ipulation of cells with growth factors, mechanical stimuli, and matrix sizing to allow implantation of mature biosynthetic grafts which woul d allow treatment of larger defects with decreased rehabilitation and morbidity.