20-year-old male presented with bilateral knee pain of 5-6months duration. He gave history of trivial trauma to the left knee 9-months back, following which he experienced insistent pain which worsened in last few months. History of vague pain was also elicited in the contralateral knee without any obvious precipitating factor.
Plain radiograph of knee joint (AP and lateral) demonstrated focal well circumscribed subchondral sclerotic lesion along both lateral femoral condyles. Magnetic resonance imaging (MRI) confirmed the presence of osteochondral defects along the posterolateral aspect of the lateral femoral condyles. There was associated marrow oedema which was confined to the lateral condyle. Mild knee joint effusion was also seen in both knees.
Osteochondritis dissecans (OCD), by definition, is a pathologic process affecting one or more ossification centers, characterised by sequential degeneration or aseptic necrosis and recalcification. The etiopathogenesis is multifactorial; trauma, ischemia, abnormal ossification, and genetic predisposition have been implicated. OCD involves both the articular cartilage as well as the subchondral bone. A small focal area of subchondral bone undergoes aseptic necrosis, while the overlying cartilage remains intact to variable degrees. As the subchondral necrotic bone is resorbed, the overlying cartilage loses its underlying support structure which may result in loose body formation. OCD most commonly involves the medial femoral condyle(85%), typically at its lateral aspect (non-weight bearing area). The weight bearing aspect of the medial femoral condyle, the lateral femoral condyle, anterior intercondylar groove or patella are uncommonly involved. Lateral femoral condyle is involved in only 10–15% cases. Bilateral osteochondritis dissecans of the lateral femoral condyle is extremely rare with very few case reports available in the medical literature.
The approximate incidence is 3 to 6/10,000 in adults. It usually manifests in 10-20 years age group and is usually more common in males (male-to-female ratio is 2-3:1). Clinical symptoms are vague and often subtle and can range from knee discomfort, knee pain, joint stiffness, and restriction in the range of joint movements to a "giving way" sensation in the knee joint. On examination, a crepitus, mild joint tenderness or effusions may be present. OCD of lateral femoral condyle is believed to be more extensive and relatively more symptomatic as compared to the medial counterpart. Additionally, an early and rapid progression of degenerative arthropathy has been observed. However, it has similar imaging findings compared with the medially located OCD. On plain radiographs, the lesion usually appears as a well circumscribed area of sclerotic subchondral bone separated from the remaining femoral condyle by a radiolucent line. Computed tomography demonstrate findings similar to those visualised on plain radiographs, however, it has the advantage of providing multiplanar reformats. MRI permits staging of the disease. It allows superior visualisation of the osteochondral defect and assists in assessing the lesion stability. Stage-I and II are stable lesions, while stage-III and IV are unstable lesions in which not only the cartilage is breached, but synovial fluid insinuates between the fragment and underlying bone. The lack of a zone of high signal intensity on T2-weighted images is a reliable sign of lesion stability. Stage-I is characterised by a subchondral lesion with a macroscopically intact cartilage. Stage-II has a cartilage defect but no loose body is formed. Stage-III is characterised by partially detached osteochondral fragment, whereas Stage-IV represents a loose body formation.
At times, normal variation in the ossification of the femoral condyle can mimic OCD. There are various MR imaging findings which can help in distinguishing this normal variant from OCD. Location in the inferocentral posterior femoral condyles with intact overlying articular cartilage, accessory ossification centers, spiculations, residual cartilaginous model, and lack of bone marrow edema favor a normal variant ossification as opposed to OCD.
Bilateral osteochondritis dissecans of lateral femoral condyle
Based on the provided anteroposterior and lateral X-rays of both knees and the MRI images of the knees, the following observations can be made:
1. There are relatively localized subchondral bone changes in both femoral condyles (mainly in the lateral femoral condyles), appearing as sclerotic bands and lucent lines, suggesting osteochondral lesions.
2. MRI reveals varying degrees of subchondral bone marrow signal abnormalities in the corresponding areas. Some lesions show low T1 signal and relatively high T2 signal, indicating changes in local bone structure and possible areas of avascular necrosis; in some images, the cartilage surface appears slightly irregular or protruding, suggesting cartilage involvement or damage.
3. No obvious signs of large free fragment detachment have been observed, but possible fissures or early signs of loosening can be seen in certain sequences.
4. No clear evidence of severe tears or degenerative changes is seen in other structures of both knees (joint space, menisci, ligaments, etc.), but further clinical assessment is needed due to differing image resolutions and areas of focus on the lesions.
1. Osteochondritis Dissecans (OCD):
- The patient is within the most common age range for OCD (10–20 years), and the subchondral bone changes in both lateral femoral condyles are consistent with OCD.
- Imaging shows sclerotic borders and potential lines of loosening, typical of OCD on imaging.
- The progression of the condition and symptoms (gradually worsening knee pain) aligns with the common clinical progression of OCD.
2. Abnormal Distal Femoral Ossification Center or Developmental Variation:
- In some cases, a lobulated or heterogeneous appearance in the femoral condyle cartilage may be due to normal developmental variations.
- However, such variations usually lack significant bone marrow edema or sclerotic borders, and the patient presents clear pain symptoms, which does not fully match a simple anatomical variation.
3. Other Causes of Subchondral Osteonecrosis or Injury:
- For instance, post-traumatic bone contusion, stress fractures, or avascular necrosis, which are typically associated with a more definitive history of trauma, localized edema, or fractures on imaging.
- In this case, only “mild trauma” is reported, and the lesions are similarly located on both sides, making a systemic or symmetrical condition such as OCD more likely.
Taking into account the patient's age, symptom characteristics, imaging findings, and disease course, the most likely diagnosis for this case is:
Bilateral Osteochondritis Dissecans in the Lateral Femoral Condyles.
If further confirmation of lesion stability or extent of cartilage damage is necessary, arthroscopic assessment or follow-up MRI is recommended.
1. Conservative Treatment
- Suitable for patients with smaller lesions, relatively intact cartilage, and relatively stable conditions.
- Includes reducing weight-bearing (e.g., wearing a knee brace or using crutches to partially offload the joint), controlling the level of physical activity, and using non-steroidal anti-inflammatory drugs (NSAIDs) to alleviate pain and inflammation.
- Regular imaging follow-up (X-ray or MRI) to monitor osteochondral healing and the risk of fragment detachment.
2. Surgical Treatment
- For larger or unstable lesions, or those with loose cartilage fragments at risk of detachment, arthroscopic intervention should be considered.
- Potential surgical procedures include arthroscopic fixation of loose osteochondral fragments, drilling to promote healing, or cartilage transplantation (e.g., autologous chondrocyte implantation or mosaicplasty).
- The choice of procedure depends on a comprehensive evaluation of the patient’s symptoms, lesion range and stability, and athletic requirements.
3. Rehabilitation / Exercise Prescription
During conservative management or postoperative rehabilitation, a gradual and individualized exercise program is recommended (following the FITT-VP principle):
This report offers a reference analysis based on available imaging and patient history and cannot replace an in-person consultation or the opinion of a professional physician. A definitive diagnosis and treatment plan should be made by a clinical doctor in consideration of the patient’s actual situation. If there are any questions or changes in condition, please seek medical attention promptly.
Bilateral osteochondritis dissecans of lateral femoral condyle
