Osteochondritis dissecans of the knee.

Williams JS Jr, Bush-Joseph CA, Bach BR Jr. Am J Knee Surg 1998 Fall;11(4):221-32

Osteochondritis dissecans is a separation of an articular cartilage subchondral bone segment from the remaining articular surface. This is a different entity from osteonecrosis, with which osteochondritis dissecans is commonly confused. In osteochondritis dissecans, the fragment separates from a vascular normal bony bed, while in osteonecrosis, the fragment typically is more peripheral and separates from an avascular bony bed. Osteochondritis dissecans is more common in adolescents and young adults, with the knee, elbow, and ankle being the most common sites. Injury to an area of fairly tenuous blood supply is the most likely cause. Treatment is typically nonoperative for stable lesions and operative for unstable lesions. Most patients do well with no long-term sequelae, but this depends on a variety of factors including the location and size of the lesion, patient age, and treatment.

Treatment algorithm for osteochondral injuries of the knee.

Cain EL, Clancy WG. Clin Sports Med 2001 Apr;20(2):321-42

The treatment of osteochondral fractures and OCD lesions in the knee is controversial. Many new procedures and techniques have been developed recently to address osteochondral lesions, indicating that no single procedure is accepted universally. Our treatment algorithm is based on the age of the patient, skeletal maturity, and the presence of adequate subchondral bone attached to the chondral lesion. Most nondisplaced lesions in the patient with open physes will heal with conservative treatment. The onset of skeletal maturity indicates a need for a more aggressive treatment approach. If adequate cortical bone is attached to the fragment, drilling of stable lesions, or drilling with fixation of unstable or loose fragments is appropriate. Autologous bone graft can be necessary to stimulate healing and properly reconstruct the subchondral bony contour. For failed fixation attempts or lesions not amenable to fixation, each treating surgeon must be proficient and comfortable with an articular surface reconstruction technique. The goal for the reconstructive procedure, to produce a smooth gliding articular surface of hyaline or hyaline-like cartilage, is possible using current techniques including mosaicplasty, osteochondral allograft transplantation, and autologous chondrocyte transplantation. Debridement, drilling, microfracture, and abrasion chondroplasty have been shown to result in fibrocartilage with inferior mechanical properties when compared with hyaline cartilage. No long-term studies have been published, however, to confirm the benefits of replacing osteochondral defects with hyaline cartilage rather than fibrocartilage. Although the results of many reconstructive procedures are quite encouraging with early follow up, the ultimate goal is to prevent long-term degenerative arthritis. Only well-designed prospective studies with long-term follow up will determine the adequacy of these procedures in reaching the ultimate goal. This treatment algorithm is based on the senior author’s (WGC) experience with the complex dilemma of osteochondral lesions of the knee.

Osteochondral injuries. Clinical findings.

Birk GT, DeLee JC. Clin Sports Med 2001 Apr;20(2):279-86

Osteochondral injuries are common, mainly affecting a young, active population. Failure to recognize these injuries can lead to long-term disability. A heightened awareness and understanding of the common mechanisms of injury will lead to early diagnosis and rapid recovery. This, along with improved treatment modalities, will keep any long-term disability to a minimum.

Osteochondritis dissecans of the knee in children. A comparison of MRI and arthroscopic findings.

O’Connor MA, Palaniappan M, Khan N, Bruce CE. J Bone Joint Surg Br 2002 Mar;84(2):258-62

The treatment of osteochondritis dissecans (OCD) in children and adolescents is determined by the stability of the lesion and the state of the overlying cartilage. MRI has been advocated as an accurate way of assessing and staging such lesions. Our aim was to determine if MRI scans accurately predicted the subsequent arthroscopic findings in adolescents with OCD of the knee. Some authors have suggested that a high signal line behind a fragment on the T2-weighted image indicates the presence of synovial fluid and is a sign of an unstable lesion. More recent reports have suggested that this high signal line is due to the presence of vascular granulation tissue and may represent a healing reaction. We were able to improve the accuracy of MRI for staging the OCD lesion from 45% to 85% by interpreting the high signal T2 line as a predictor of instability only when it was accompanied by a breach in the cartilage on the T1-weighted image. We conclude that MRI can be used to stage OCD lesions accurately and that a high signal line behind the OCD fragment does not always indicate instability. We recommend the use of an MRI classification system which correlates with the arthroscopic findings.

Arthroscopic versus conservative treatment of osteochondritis dissecans of the knee: value of magnetic resonance imaging in therapy planning and follow-up.

Jurgensen I, Bachmann G, Schleicher I, Haas H. Arthroscopy 2002 Apr;18(4):378-86

PURPOSE: Magnetic resonance imaging (MRI) was used to control the short-term outcome of osteochondritis dissecans (OCD) of the femoral condyle depending on conservative or surgical treatment at the beginning of therapy. TYPE OF STUDY: Case series. METHODS: Treatment planning for OCD depended on the stage on MRI when analyzing the appearance of the interface between parent bone and fragment on T1- and T2-weighted images. Twenty-seven patients received conservative treatment and 46 patients underwent arthroscopic surgery. After 20 to 24 months, patients were re-evaluated by MRI to assess the condition of bony fragment, parent bone, and interface so as to determine partial or complete remission, no change, or progression of OCD. RESULTS: After conservative treatment, MRI showed partial or complete remission in 30% of patients and no change in 63%. Arthroscopic treatment led to remission in 37% and to no change in 57%. Progressive disintegration of OCD was found on MRI in 7% of conservatively treated patients and in 7% of the surgery patients. In 33.3% of the patients initially treated conservatively, it was decided to treat them arthroscopically because of ongoing, unacceptable clinical symptoms. CONCLUSIONS: The rates of remission and progression were not significantly different between the groups. The patients’ age was significantly correlated to the rate of consolidation. OCD in juveniles under 16 years of age followed a milder course than in adults.