Overview
The knee joint is the most common site of osteochondritis dissecans (OCD).
While it is most commonly detected in the femoral condyles, it has also been reported to occur in the patella.
It is believed to be primarily caused by repetitive, chronic trauma that leads to osteonecrosis of the subchondral bone.
Repetitive joint overload has been identified as the most important cause of patellotrochlear OCD. The presence of concomitant patellar subluxation in approximately 50% of patients reinforces this view.1**
Staging of osteochondral lesions
Stage 1: chondral mound formation, stage 2: partial chondral separation, and stage 3: joint mouse formation.
These are usually patients who are active in sports and are in the adolescent growth spurt.
Clinical findings
Anterior knee pain and tenderness, painful gait, effusion, and limitation of knee movements.
Standard radiographs, including axial radiographs of the knee, will be sufficient to distinguish between stage II and stage III lesions.
Magnetic resonance imaging (MRI) can detect cases of OCD at an earlier stage. It can also monitor the response to treatment in patients who have undergone conservative and surgical treatment.
Treatment
Conservative treatment is an appropriate treatment option
Surgical treatment may include osteochondral drilling, autologous cartilage transplantation, microfracture, fragment fixation, or joint mouse excision.
The current preferred method is arthroscopic drilling or microfracture for stable lesions, followed by stabilization with resorbable pins for unstable lesions, and excision of any loose fragments. Immobilization of the knee to prevent weight-bearing on the patellofemoral joint is recommended for 4-6 weeks after treatment. The success of surgical treatment depends on the size of the lesion, the stage of the disease, and the patient's skeletal age. 2**
Trochlear OCD cases have been reported less frequently. Generally, surgical drilling and curettage are recommended for cartilage lesions in the trochlear region.
Similarly, four weeks of immobilization are recommended after surgery. A quadriceps rehabilitation program should be implemented after immobilization. For non-separated lesions, successful results have been reported even in fully developed knees, with the application of an eight-week cast.3**
1**Thabit G 3rd, Micheli LJ. Patellofemoral pain in the pediatric patient. Orthop Clin North Am 1992;23:567-85.
2**Kocher MS, Tucker R, Ganley TJ, Flynn JM. Management of osteochondritis dissecans of the knee: current concepts review. Am J Sports Med 2006;34:1181-91.
3** Peters TA, McLean ID. Osteochondritis dissecans of the patellofemoral joint. Am J Sports Med 2000;28:63-7.