Osteochondritis Dissecans of the knee is a common condition, mainly affecting very active children and young adults. It is more common in boys than girls and it is thought to result from multiple minor traumatic episodes. The vast majority of the lesions are situated in the Medial Femoral Condyle (85%). The lateral femoral condyle is next most common (12%), followed by the trochlea and then the patella (1%).
The condition presents with pain around the area of the OCD. The patients can be a young as 8 at presentation. Xray and MRI are used to make the diagnosis and determine the stage of the OCD, and the condition of the articular cartilage overlying the affected bone.
Treatment
Treatment is dependent on the age of the patient at initial presentation. Children less than 10 years of age are usually treated non-operatively. Children over 12 , where symptoms have lasted more than 6 months, have an increasing chance of needing surgery. If the articular cartilage overlying the OCD has started to break down, the symptoms change. Swelling, giving way and locking are worrying symptoms. MRI is the investigation of choice to stage the lesion, check for articular cartilage breakdown and loose bodies within the knee.
If the articular cartilage is intact, arthroscopic drilling is performed under Xray control. This is done through 2 or 3 small incisions and is done as a Day Case. Postoperatively, crutches and a brace are used for 6 weeks. Healing occurs in approximately 90% of patients.
If the articular cartilage is breaking down, internal fixation is required. Small nails (Polylactic Acid) or screws are used either arthroscopically or through a small arthrotomy as an open procedure. The patient stays in hospital one night if an arthrotomy is needed. The postoperative course is then similar to arthroscopic drilling.
Less commonly, other forms of treatment are required, such as bone grafting beneath the lesion, or using an osteoarticular graft. Allograft (donor tissue) is rarely.
It is extremely important to preserve the articular cartilage in children and adolescents. If the osteoarticular fragment has broken away, it must be internally fixed, even if it appears to be articular cartilage alone. The success rate of this procedure is reasonably high in childhood.