OCD is a condition affecting the joints of school-aged or adolescent children. The most common joints affected are the knee, elbow and ankle. It causes pain that is usually worse with activity.
What is OCD?
OCD affects the bone just below the cartilage of the joint (subchondral bone). In some adolescents, a small part of this bone dies (osteonecrosis) and this creates a fragment of necrotic bone and the articular cartilage directly over it to separate from the rest of the bone. The fragment either stays in the hole it creates or separates completely from the bone forming a loose body in the joint. It is not well understood why this happens or what causes it, but possible mechanisms include minor repetitive trauma to the area and damage to the small blood vessels supplying the bone, local ischaemia after a single injury and genetic predisposition.
Males are almost 4 times as likely as females to get OCD and 75% of the time it affects the knee joint. 60% of cases are in children or adolescents involved in high-level competitive sport and 20% of the time it occurs in both limbs.
OCD of the knee
The classic presentation is a 13-year-old boy with knee pain. The pain could be precipitated by a traumatic event at sport or slowly develop over a few months in highly active people. Pain is worse with activity and there may be mechanical symptoms such as locking if there is a loose body. Swelling occurs in approximately 20% of cases and sometimes there is associated stiffness. The adolescent may walk with a limp and may have their foot turned outwards to avoid pain.
Diagnosis is usually made with a combination of clinical examination and imaging. X-ray can be normal in the early stages and MRI is sometimes needed for diagnosis but is not as accurate when the growth plates are still open compared to when they are closed.
There is poor understanding of the natural history of the condition if left untreated and the treatment varies depending on the stability of the lesion (if it has formed a loose body or is still in place). Non-operative treatment involves immobilisation for a period of time followed by physiotherapy and rehabilitation prior to return to activity. The whole process usually takes about 6 months to get the adolescent back to pain free sport. Sometimes surgery is needed for unstable lesions or those that haven’t improved after 6 months of non-operative treatment. Most OCD in children or adolescents does eventually recover and the prognosis is much better if the growth plates are still open at the time of diagnosis.
OCD of the elbow
The elbow is the second most common joint affected by OCD. It mainly occurs in children and adolescents aged 10 – 16 years. There is usually a history of repetitive minor trauma from upper limb weight bearing or throwing. This results in elbow pain with or without swelling and locking. The pain is exacerbated by throwing and upper limb weight bearing activities. Like in the knee, management depends on the stability of the lesion. It is important to recognise the condition early with an accurate diagnosis because long-term disability can result if missed.
OCD of the ankle
OCD of the ankle usually presents as a lateral ankle sprain that isn’t improving as expected.
If your child has joint pain that is worse with activity, a consultation at Shire Sports Medicine can be beneficial to get an accurate diagnosis, to help guide management and to ensure the prevention of further complications.