Knee pain in children and adolescents has many origins. One of these conditions is Osteochondritis dissecans (OCD) which develops in joints. It occurs when a small segment of bone begins to separate from its surrounding region due to a lack of blood supply. As a result, the small piece of bone and the cartilage covering it begin to crack and loosen. It is not known exactly what causes the disruption to the blood supply and the resulting OCD. Doctors think it probably involves repetitive trauma or stresses to the bone over time. Think of this lesion kind of like a pothole in the street, where the overlying cartilage is the cement road, and the underlying bone is similar to the ground beneath the road. For those who play golf, an OCD is not unlike a “divot” you may take with your golf swing.
The condition typically affects just one joint, however, some children can develop OCD in several joints. The most common location of OCD is in the knee at the end of the femur (thighbone).
Pain and swelling of a joint — often brought on by sports or physical activity — are the most common initial symptoms of OCD. Advanced cases of OCD may cause joint catching or locking. Depending on where the OCD lesion is in the knee, it may affect the symptoms patients are having. Usually, activity such as lunging, squatting or kneeling tend to make the symptoms worse. Sometimes, just pain and/or swelling are present.
Diagnosis typically initially involves an x-ray which usually will identify the lesion. An MRI is usually ordered to better delineate the size of the lesion and to determine if the lesion appears to be stable or unstable.
In many cases of OCD in children, the affected bone and cartilage heal on their own, especially if a child is still growing. These are typically stable lesions with intact overlying cartilage and no fluid tracking from the joint under the lesion which causes the OCD to not heal and/or loosen over time as the lesion tends to move. If symptoms do not subside after a reasonable amount of time, the use of crutches, or splinting or casting the affected joint for a short period of time may be recommended. In general, most children start to feel better over a 2- to 4-month course of rest and nonsurgical treatment. They usually return to all activities as symptoms improve.
In grown children and young adults, OCD can have more severe effects. Unstable, OCD lesions have a greater chance of separating from the surrounding bone and cartilage, and can even detach and float around inside the joint. Some common indications for surgery are:
• Nonsurgical treatment fails to relieve pain and swelling
• The lesion is separated or detached from the surrounding bone and cartilage, moving around within the joint
• The lesion is very large (greater than 1 centimeter in diameter), especially in older teens
There are different surgical techniques for treating OCD, depending upon the individual case.
• Drilling into the lesion to create pathways for new blood vessels to nourish the affected area. This will encourage healing of the surrounding bone.
• Holding the lesion in place with internal fixation (such as pins and screws).
• Replacing the damaged area with a new piece of bone and cartilage (called a graft). This can help regenerate healthy bone and cartilage in the area damaged by OCD. The graft may come from the patient (autograft), whereas larger lesions may require the use of a fresh frozen allograft (cadaver).
In general, crutches are required for about 6 weeks after surgical treatment, followed by a 2- to 4-month course of physical therapy to regain strength and motion in the affected joint. A gradual return to sports may be possible after about 4 to 5 months.