Management of osteochondral injuries of the knee

Osteochondral injuries of the knee have proven to toe a challenge for the o rthopaedic surgeon. The lack of long-term studies and no general consensus as to the best way to manage these lesions compounds the challenge. New pro cedures, technologies and improved assessment tools seek to address these i njuries, which can cause significant disability, particularly in the young healthy patient. This review examines some of the more common techniques us ed in managing osteochondral injuries in the knee. Ulcerated cartilage is a troublesome thing, once destroyed is not repaired. HUNTER, 1743(22) The search for the best management for articular cartilage injuries has cha llenged the practice of medicine since the recognition of osteochondral inj ury as a distinct entity with its own pathophysiology. Curl et al showed in their review of 31,516 patients that these injuries were found in 63% of t he arthroscopies.(15) Therefore, this is a clinical problem that the practi cing orthopedic surgeon will face often. Articular cartilage is not an inert tissue; it can remodel and rebuild itse lf in a limited fashion. Multiple studies have shown the metabolically acti ve nature of this tissue, which underlies many procedures aimed at repair o f focal chondral injury.(44) The unique physiology of this tissue and its a bility to heal when damaged requires consideration of the multilayered orga nization of articular cartilage and the role of the subchondral bone in pro viding the cellular and humoral factors for healing. Developments in the un derstanding of the pathophysiology of articular cartilage and subchondral b one has given a more scientific focus to the management of this challenging clinical entity The depth of the articular insult directly influences the rate and ability of hyaline cartilage to heal. Mesenchymal stem cells, humoral factors, and the fibrin clot needed for preparing a milieu to promote repair are found i n the subchondral bone deer to the tidemark, Pridie in 1959 was the first t o demonstrate this concert when he noticed a fibrous repair tissue after pe netration of the subchondral plate in eburnated bone.(50) This basic concep t underlies therapies that focus on penetration of the subchondral plate to promote healing. The cascade of events that begins with osteochondral injury may lead to pai n, swelling, and the joint deformity. Several options are available to trea t isolated osteochondral injuries, which occur more frequently on the femor al side. The last decade has provided numerous procedures involving stimula tion of subchondral bone, autologous transplantation and transplantation of cultured tissue, periosteum, perichondrium and artificial matrices, in eff orts to restore the articular cartilage surface. The diagnosis of osteochondral injury is part of a differential diagnosis t hat might include meniscal injury, loose body, and ligamentous injury. Diag nosis is further challenged by the necessity of making distinctions between focal cartilage injury and the degeneration that is considered to be osteo arthrosis.(36) This is an important distinction because the outcome and ran ge of procedures available for the degenerative knee differ from that of di screte osteochondral injuries. The disability accompanying osteochondral injury can be significant and sev erely limit the functional capabilities of the knee.(7) Plain radiography h as variable accuracy in diagnosing degenerative disease particularly in the early phases. Lysholm ct al showed that arthroscopic examination that reve aled Outerbridge II and III changes often were found to have "normal" knee radiographs.(34).