Treatment of osteochondral injuries - Genetic engineering

Articular cartilage lesions in the knee joint are common sports-related inj uries.(20,) (27) The incidence of articular surface injuries is reported as high as 42% in arthroscopically examined patients with post-traumatic knee disorders.(27) In a review of 31,516 knee arthroscopies, 53,569 hyaline ca rtilage lesions were documented in 62.9% of patients with most of the sever e Grade IV cartilage injuries located on the medial femoral condyle.(17) Injuries of the articular surface originate either from direct trauma or fr om indirect, twisting injuries of the knee joint. Frequently, injuries of t he articular cartilage are associated with anterior cruciate ligament (ACL) ruptures. Magnetic resonance (MR) imaging studies demonstrated bone bruise s in 68% of patients with acute ACL tears.(20) Although no relationship bet ween hone bruises and osteochondral lesions or osteoarthritis could be prov ed directly in the past, a significantly higher prevalence of articular cho ndromalacia is seen in patients with untreated ACL injuries.(20) In a prosp ective study, Daniel et al have demonstrated that degenerative changes of t he articular cartilage will develop regardless of the treatment in all pati ents following an ACL rupture.(18) Articular cartilage possesses a limited capability to regenerate, and in mo st injuries of the articular surface, premature osteoarthritis will develop in the affected knee joint.(42) Although elderly patients with severe arth ritic conditions profit from total joint replacement, there is an urgent ne ed for a valid treatment for articular cartilage damage in young and middle -aged persons.(52) Although current treatment concepts for articular cartil age injuries are promising,(5,33) to date, no therapy concept has resulted in complete restoration of the hyaline cartilage and the subchondral bone t o a normal status. The advent of gone therapy and tissue engineering has promoted novel strate gies for the treatment of chondral and osteochondral injuries. Large scient ific contributions have been made in the last 20 years toward understanding the biology of articular cartilage and toward new approaches to therapy Th e delivery of growth factors, cells, scaffolds, and therapeutic genes into articular cartilage lesions promises to revolutionize a medical field histo rically limited to frustrating outcomes. Despite the significant progress i n treating osteochondral lesions, many questions currently remain unanswere d. This article discusses the current status of tissue engineering and gene transfer for disorders of articular cartilage and the focus of ongoing exp erimental investigations.