Osteochondritis Dissecans of the Knee

Osteochondritis dissecans (OCD) of the knee joint is a condition that causes loosening of cartilage and its supporting bone. OCD most often occurs in the knee, although it can also occur in other joints, including the ankle and the elbow.

As the blood flow to the bone is diminished, the attached cartilage can separate away from the bone. The cause of OCD is not well understood, but it is thought to be related to repetitive stress or traumatic injury to the bone.

How OCD Affects Joint Cartilage

Your joint cartilage helps your joints bend smoothly and painlessly. In a normal knee joint, a layer of cartilage several millimeters in thickness evenly coats the bone surfaces. Healthy cartilage is smooth, slippery, and firmly attached to the underlying bone. 

With OCD, a deficiency of blood flow damages the bone. This can cause the bone to fragment and the cartilage to separate from its normally firm attachment.

In OCD, a cartilage fragment can loosen and break off from the joint surface. 

Symptoms of OCD of the Knee

When cartilage is damaged, a number of problems can occur.

Symptoms of OCD include:

• Joint pain
• Knee swelling
• Knee locking
• Instability of the joint

You can experience severe symptoms when there is a fragment of cartilage floating around the joint.

Treatment of OCD of the Knee

There are a number of factors that your doctor will discuss with you when considering the best treatment approach for your OCD.

Considerations

• Patient Age: The most important prognostic factor is age. Children and adolescents have open growth plates, and this is associated with a much better OCD prognosis and a higher chance of healing with both surgical and non-surgical treatments.
• Size and Location: Larger fragments or fragments in more critical parts of the joint are generally treated with surgery.
• Degree of Fragmentation/Detachment: OCD fragments are classified as either being stable or unstable, depending on the likelihood of the fragment separating from the bone.
• Stable fragments are more likely to heal with less-invasive treatment.
• Unstable fragments are more susceptible to separation and are most often surgically repaired.

Non-Surgical Treatment

Depending on your situation, your orthopedic surgeon can make a recommendation for treatment. Sometimes non-surgical treatment can be effective.

The vital part of non-surgical treatment is resting the joint so it can heal. This means limiting activity and may mean using crutches to limit weight on the joint. Your doctor may also recommend treatments to reduce your symptoms while you heal—including ice and anti-inflammatory medications.

Surgical Treatment

The goal of surgical treatment is for you to end up with a stable cartilage surface in your knee joint.

If your doctor anticipates that the fragment can heal, your surgeon will most likely repair the OCD lesion, usually by using screws or pins to hold the fragment in place. Modern screws and pins are made of bioabsorbable material (rather than metal) so that they will not cause future problems to the joint cartilage.

If the likelihood of healing is low, the loose cartilage will be removed from your knee, and treatment will be focused on stimulating new cartilage growth in the void on your joint surface. 

Methods of Stimulating New Cartilage Growth

There are a number of ways to try to stimulate new cartilage growth, and each has pros and cons:

• Microfracture: A microfracture surgery stimulates blood flow to the area of damage, which can allow cartilage healing. This treatment is seldom used for juvenile OCD because it does not hold up over time.
• OATS/Cartilage Transfer: During a cartilage transfer procedure, healthy cartilage and bone are taken from areas of the joint that don't need the cartilage to the area of damage.
• Autologous Chondrocyte Implantation (ACI): Cartilage cells are grown in a lab, and then inserted into the area of damage.