Osteochondritis Dissecans

What is osteochondritis dissecans?

Osteochondritis dissecans is a condition that occurs in the joints (the place where the end of one bone meets the end of another bone) when a lack of blood to the joint causes the bone inside to soften. This results in a small piece of the bone dying and separating from the larger bone. This bone piece, along with cartilage that covers and protects the bone, can then crack and break loose.

The loose bone and cartilage might remain in place, or they can move into the joint area, which causes the joint to become unsteady. The condition leaves a lesion where the bone and cartilage separate. The entire process can take months or even years, and symptoms may take a long time to appear.

Osteochondritis dissecans usually affects the knee at the end of the thighbone (femur), ankle and elbow. The condition can also occur in other joints, including the shoulder and hip.

Osteochondritis dissecans usually develops in just one joint. When only one lesion occurs in a single joint, the condition is known as sporadic osteochondritis dissecans.

Who is affected by osteochondritis dissecans?

Osteochondritis dissecans occurs most often in children and adolescents ages 10 through 20, especially in young athletes or those who are physically active. However, people of any age can develop the condition.

Rarely, osteochondritis dissecans appears in more than one joint, and perhaps in more than one family member (familial osteochondritis dissecans). People who have this type of osteochondritis dissecans usually have a short stature and a tendency to develop osteoarthritis – a breakdown of bone and joint cartilage – early in life.

What causes osteochondritis dissecans?

The causes of sporadic osteochondritis dissecans are mostly unknown. One possible explanation is that repeated trauma or stress to a joint over time – by playing sports, for example – can lead to the condition.

Familial osteochondritis dissecans is caused by inherited mutations (changes) to the ACAN gene, which is the source of a cartilage-building protein called aggrecan. Because of the mutation, the protein cannot build cartilage like it should, so the cartilage is weak and disorganized. However, it’s uncertain how the weak and disorganized cartilage results in bone separation and lesions.

What are the symptoms of osteochondritis dissecans?

If the separated bone and cartilage stay close to the larger bone, there may not be any symptoms. If symptoms do exist, they can include:

• Pain, weakness and/or swelling in a joint, often after physical or athletic activity;
• Decreased range of motion (the distance a joint normally moves), including an inability to fully extend the arm or leg. This is more likely to happen if the detached bone and cartilage drift into the joint space.
• Stiffness in the joint after resting;
• Locking or sticking of a joint in one position;
• A clicking sound when moving the joint.

How is osteochondritis dissecans diagnosed?

To diagnose osteochondritis dissecans, the doctor will perform a physical examination and will assess the joint’s stability. The doctor may order tests, including the following:

• X-rays, which will show the bone, locate the lesion and reveal its size.
• A magnetic resonance imaging test (MRI), along with an ultrasound. These can produce clear images of the affected cartilage, and can show if the detached bone and cartilage have moved into the joint space.
• A computed tomography (CT) scan, which displays more internal details – including bone, blood vessels and soft tissues – than conventional X-rays.

If familial osteochondritis dissecans is suspected, a genetic test can spot changes in genes, chromosomes and proteins.

How is osteochondritis dissecans treated?

In children and younger teens, sporadic osteochondritis dissecans will usually heal on its own as they grow older. They can relieve pain and swelling with rest and time off from vigorous physical activities such as running and jumping. The doctor may recommend a nonprescription pain reliever/anti-inflammatory medication, like ibuprofen (Advil®, Motrin®).

After six to 12 weeks, the injured joint will start functioning normally again. The child should resume athletic activities gradually with gentle exercises (stretching, swimming, biking or yoga).

If the healing is slow, the doctor may suggest the use of crutches, or may place a brace, splint or cast on the joint. The doctor may also recommend the patient have physical therapy.

The doctor may recommend surgery for osteochondritis dissecans if:

• Rest and time don’t reduce pain and swelling.
• Tests reveal that the detached piece of bone and cartilage are moving around in the joint space.
• The detached bone and cartilage are larger than 1 centimeter in diameter.

The surgery is often performed arthroscopically (with small tools and a camera through tiny incisions). There are three surgical techniques:

• Drilling a hole into the affected bone and cartilage. This creates a path for new blood vessels to form, bringing oxygen and healing to the bone.
• Securing the detached bone and cartilage in place with pins and screws.
• Replacing the detached bone and cartilage with a graft to create healthy tissue in the damaged area. Bone and cartilage are taken from another part of the body or from a cadaver. Doctors can also take a sample of healthy bone and cartilage from the patient and use it to grow new bone and cartilage in the lab.

After surgery, the patient will use crutches for about six weeks, and then undergo physical therapy for two to four months to build strength and restore the joint’s range of motion. The patient might be able to resume rigorous physical activity four to five months after surgery.

Can osteochondritis dissecans be prevented?

It can be difficult to prevent osteochondritis dissecans since its causes aren’t known. Young children playing sports can take measures to protect their joints by, for example, wearing pads and protective gear. It’s also important for them to practice the proper physical techniques in their sport, to stretch and warm up before vigorous physical activity and to stretch and cool down afterward.

What is the prognosis (outlook) for someone who has osteochondritis dissecans?

The younger the patient, the better the chance of full recovery and a return to pre-injury activities. However, the patient might have to give up sports activities that require repetitive motions, like pitching.

Adults are more likely to need surgery for osteochondritis dissecans and are less likely to fully recover. Adults also are also more at risk for developing osteoarthritis in the injured joint.

Osteochondritis dissecans usually doesn’t return once the patient heals. However, sometimes the condition only seems to heal as symptoms go away temporarily. In those cases, symptoms can return in time.