BLOG: Bilateral osteochondritis dissecans of the lateral femoral condyles
Osteochondritis dessicans lesions of the lateral femoral condyle occur relatively infrequently and are even more rare in bilateral knees. This case study is an example of such a diagnosis. The author then reviews the etiology, prevalence, history, physical exam, diagnostic imaging and treatment options and outcomes for OCD lesions of the knee. Treatment options are controversial and are typically based on the staging of the lesion.
- Sam Dyer, PA-C, MHS
A 13-year-old male basketball player with significant past medical history of left lateral femoral condyle osteochondritis dissecans lesion presented to pediatric orthopedic surgery clinic.
He had with a 3-month history of right knee pain and 1-week history of knee locking. His previous osteochondritis dissecans (OCD) lesion was high grade with delayed healing, and he was 1-year status after left knee arthroscopy with loose body removal and microfracture. On physical exam, his right quadriceps circumference was decreased compared with the left and there was tenderness to palpation over the inferior pole of the patella and the lateral fat pad on the right knee. Wilson’s sign was positive on the right, and he had full range of motion bilaterally. Radiographs of bilateral knees demonstrated a lucent lesion in the subchondral anteromedial aspect of the right lateral femoral condyle, similar in location to the lesion on his contralateral knee 1 year ago. A right knee MRI was completed and revealed a grade 2 OCD lesion of the anteromedial aspect of the right lateral femoral condyle. Both operative and nonoperative options were discussed with the family but given the patient’s history of a contralateral high-grade lesion with delayed healing, surgical management was chosen. As the lesion was attached and non-displaceable, a right knee arthroscopy with OCD drilling and internal fixation was performed.
After the procedure, the patient was placed in a drop lock knee brace locked in extension, with weight-bearing as tolerated for 5 weeks and began physical therapy. Two months postoperatively, the patient had full range of motion and strength and denied any pain or tenderness. Radiographs demonstrated interval healing of the OCD lesion, and he began gradual progression to sports activities. Five months postoperatively, he was given full clearance.
The definitive cause of OCD is unknown, but there are numerous proposed etiologies including repetitive microtrauma, genetic predisposition, failure of the vascular architecture at the perichondrium and local ischemia after a single injury. In pediatrics, OCD lesions are generally seen in children involved in high levels of sports activities, favoring the theory of repetitive microtrauma as the primary mechanism of injury.
The overall prevalence of pediatric OCD lesions of the knee is estimated to be 15 to 29 per 100,000 patients, with about 70% distributed in the medial femoral condyle and the rest in the lateral condyle, with bilateral involvement in less than 10% of patients. In a large observational study of more than 1 million patients, 192 children ages 6 to 19 years were found to have OCD of the knee, with a 4:1 male to female predominance, and highest incidence in patients 12 to 19 years old.
Active patients with OCD lesions of the knee generally present chronically, with worsening symptoms in several months. Early stage OCD lesions typically present with nonspecific, poorly localized knee pain with activity. But as the injury progresses, gradual onset of stiffness and intermittent swelling during and or after activity occurs. If a high-grade lesion is present or it has become a loose foreign body, the patient may experience catching or locking of the knee
When an OCD is suspected, patients should receive initial plain radiographs of bilateral knees as bilateral OCD lesions are found in up to 25% of patients, as well as it can be helpful for differentiation of OCD lesions from normal variations in ossifications of femoral condyles in pediatric patients. If radiographs are negative but clinical suspicion remains high, or for grading of lesions (stages I-IV) and surgical planning, MRI without contrast is the study of choice.
Treatment of OCD of the knee consists of either operative or nonoperative management. Recommended treatment is based on the likelihood of healing nonoperatively, which is largely determined by skeletal maturity and characteristics of the OCD, such as size or stability. Initial nonoperative management is suggested for children with stage I, II or III OCD of the knee and generally consists of restriction of activities, immobilization for 4 to 6 weeks, physical therapy and gradual return to sports once asymptomatic, which generally takes 6 months. Although this is considered the standard of care, no prospective studies have determined the efficacy of these conservative methods and no one treatment method for either the stable or unstable lesions has demonstrated superiority.
Surgical management is warranted for children with OCD who have a loose foreign body or have not responded to 4 to 6 months of nonoperative therapy. There are multiple surgical techniques, including arthroscopic drilling, metallic screw fixation, bioabsorbable fixation, microfracture and chondrocyte transplantation. The choice of technique depends upon the patient’s skeletal maturity, the stage of the OCD fragment and the size of the lesion. Postoperative management recommendations vary depending on the surgeon’s protocol.
Healing rates are dependent on the age of the patient and stage of the lesion; in nonoperative management these vary from about 50% to more than 90%, with the highest rate of healing occurring in patients with stage I OCD. Overall, patients with complete healing of OCD should have full recovery of joint function, and roughly 50% of patients with stage III or IV lesions are at risk for chronic pain, mechanical symptoms and arthritis.
An OCD lesion of the knee is a relatively common pediatric injury. Most occur chronically during several months from repeated stress or microtrauma with high levels of activity. OCD lesions should be on the differential diagnosis for all patients presenting with gradual onset of pain, stiffness and intermittent swelling during or after activity, and or any catching or locking of the knee. These patients warrant knee radiographs to evaluate for OCD lesions, as early intervention can limit progression of lesions and increase the likelihood of healing with nonoperative management, ultimately decreasing long-term complications. However, despite early intervention, healing rates are dependent on age of the patient and state of the lesion, and patients are at risk for chronic pain, mechanical symptoms and arthritis no matter the intervention. It is important to appropriately screen for these injuries and continue to research both preventative measures and the most appropriate management as there is still controversy about the standard of care.
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