- Osteochondritis dissecans (OCD) is an acquired, reversible, idiopathic lesion
- Disorder of subchondral bone leading to cartilage lesions
- Lateral aspect of medial femoral condyle most common location
- Up to 25% bilateral
- Skeletally immature patients have higher likelihood of healing lesion with non-operative management
Description:Osteochondritis Dissecans (OCD) of the knee is an acquired, reversible, idiopathic condition of the subchondral bone. The cause is currently unknown but it may lead to damage to overlying cartilage, loose bodies, and joint damage.
Epidemiology:Incidence reported around 9/100,000 in children under 11 years old and 22/100,000 in adolescents 12-19 years old. Boys have a higher incidence then girls. Reported incidence is on the rise. Lesions are bilateral approximately 25% of the time. Adult OCD lesions are thought to be persistent or untreated juvenile OCD lesions, though de novo adult lesions have been described.
Clinical Findings:Symptoms can vary from vague knee pain to mechanical symptoms due to an unstable fragment. Pain with activity and recurrent effusions are common. Patients may present with an antalgic or externally rotated gait and can be tender to palpation at the site of the OCD lesion. Pain with tibial internal rotation with the knee flexion may indicate medial femoral condyle OCD lesion (Wilson sign). Patients with mechanical symptoms, effusions, crepitus or pain with motion more typically have unstable OCD lesions.
Imaging Studies:AP, Lateral, Tunnel, Sunrise knee radiographs. Patients under age 7 may have anatomic variants of normal ossification centers that should not be confused as OCD lesions. Determining skeletal maturity will assist in prognosis and treatment. MRI recommended for staging and treatment guidance. A high signal line behind the fragment seems to be most predictive of unstable lesions and potential failure of non-operative treatment. Bone scans have also been used to assess healing potential of OCD lesions.
Lesions descriptions include chronological age, anatomical location, radiographic findings, and surgical appearance. Lateral aspect of the medial femoral condyle is most common location (approximately 60%). Lateral femoral condyle OCD lesions (30% of lesions) associated with discoid meniscus. Trochlear OCD lesions are rarest location and commonly missed on plain radiographs.
The Hefti Classification is used for describing MRI findings of OCD Lesions. 1) Small change of signal without clear margins of fragment 2) Osteochondral fragment with clear margins but without fluid between fragment and underlying bone 3) Fluid is visible partially between fragment and underlying bone 4) Fluid is completely surrounding the fragment, but the fragment is still in situ 5) Fragment is completely detached and displaced (loose body)
Treatment:Lesion size, location, stability and symptomatology should be taken into account when determining treatment algorithms. Skeletally immature patients respond well to non-operative management including activity and weight bearing restrictions, casting, or bracing. Excessive running and jumping in sports may need to be limited. Age appropriate participation in sports may be possible if no effusion or signs of instability of the lesion. The extra sessions of conditioning and training should be stopped. Some high level competitive sports (gymnastics, year round basketball, soccer, etc.) may not allow participation with restrictions.
Operative management is typically offered for skeletally mature patients, unstable lesions, and stable lesions not responding to non-operative management. Operative interventions include trans-articular/retro-articular/notch drilling, internal fixation, bone grafting and fixation, osteochondral autograft, and osteochondral allograft techniques.
Postoperative healing time is approximately 3-6 months depending on the size of the lesion. Radiograph and MRI follow up are generally recommended before returning to sport.
Complications:Short term complications include nonunion/nonhealing of the OCD lesion, hardware removal if pin fixation used, standard postoperative complications, and loose body damage throughout knee. Long term complication includes osteoarthritis.
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