Osteochondritis Dissecans (OCD)
What is Osteochondritis Dissecans (OCD)?
Osteochondritis dissecans (OCD) is the formation of cracks in articular cartilage (surface lining of the bone) and the underlying bone. The knee is most commonly affected.
This may be followed by separation of the piece of bone and its attached surface lining (osteochondral fragment) from the main piece of bone.
Although the name “osteochondritis” implies inflammation there is no inflammation seen.
What causes OCD?
The cause of OCD is not yet clear, as both trauma (damage) and ischemia (lack of blood supply) have been thought to be involved.
There are 2 forms of OCD. The juvenile (childhood) form appears before closure of the physeal plates (growth areas) and an adult form.
High-impact sports, such as gymnastics, soccer, basketball, lacrosse, football, tennis, and baseball, have been associated with a higher risk for OCD.
Other factors, such as rapid growth during puberty, deficiencies and imbalances in the ratio of calcium to phosphorus, and anomalies of bone formation, have been suggested to have a role in the development of OCD, but clear evidence is lacking.
There may be a genetic predisposition (runs in families).
What symptoms can OCD cause?
Damage to the joint lining can present with pain, swelling, locking and giving way. Symptoms may be made worse with activity. Sometimes there may be no symptoms.
The OCD fragment can remain attached, partially detached, or detach completely. A completely detached fragment becomes a loose body. The fragment can move around the joint causing further damage to the surface lining.
What signs may be found in the joint when examined?
When the leg is involved, patients often present with a limp.
Clinical signs include joint swelling, tenderness over the damaged area when pressed on, muscle wasting and weakness.
If the fragment separates completely it may cause locking and giving way. Occasionally, the loose body may be palpable. The patient may lack full knee straightening.
How common is OCD?
OCD is a rare, occurring in 15-30 per 100,000 people in the general population each year.
OCD tends to affect young patients, with an average age at presentation of 10-20 years (but it may occur in persons of any age). It is twice as likely to occur in males.
The incidence increases with an increasing level of participation in competitive sports among both boys and girls.
What joints are most affected?
The knee is affected in 75% of cases, the elbow in 6% of cases, and the ankle in 4% of cases.
The diagnosis of any condition involves taking a history from the patient, examining them and then undertaking appropriate investigations.
The patient may give a classical history and examination, or not.
It is common to undertake an xray or MRI. MRI is the best test and can help show the lesion and its stability.
How is OCD treated?
The treatment of OCD of the knee depends on the age of the patient and how severe the problem is. In general, the younger the patient, the better the outlook, especially if they are still growing.
In children with nondisplaced fragments who are still growing, initial treatment includes limitation of activity, restriction of range of motion, ( range-of-motion brace), cryotherapy, and oral analgesics.
In children who are approaching the end of growth or have a big defect, a trial of nonsurgical treatment may be recommended for 3-6 months. If symptoms persist or the fragment fails to unite, patients should be treated surgically.
Adults may also be given a trial of conservative (non surgical) treatment. However, they are less likely to improve without surgical intervention. Therefore, in adults, the threshold for surgery is lower.
Surgery is usually performed arthroscopically. Currently, there are several surgical options, including drilling of the fragment to stimulate healing, pin or screw fixation of the fragment, removal of loose bodies, osteochondral autograft or allograft transplantation, and autologous chondrocyte implantation.
The success rates of the above-mentioned procedures vary in different studies and depend on the patient’s age and OCD grade.