Osteochondritis of the Knee
Osteochondritis dissecans (aka “OCD”) is a condition in which the bone that supports the cartilage inside a joint undergoes softening. This softening is caused by an interruption in the blood flow to that portion of bone. Over time, if left untreated, this can lead to damage to the overlying cartilage of the joint. Loose pieces of bone and cartilage can even break off into joint. Long term ramifications may even include arthritis.
What Causes OCD?
No one knows exactly what causes OCD, but it has been associated with acute injuries as well as long term repetitive impact to the joint (overuse injuries). It may also be related to problems with blood supply. Osteochondral fracture (when a piece of bone that also contains joint cartilage breaks off in the joint) or chondral injury (an injury just to the cartilage in the joint) is similar to OCD, but it is generally caused by an acute injury to the cartilage and underlying bone. It can happen in association with ligament injuries, such as tearing of the ACL. OCD (osteochondritis dissecans), on the other hand, is considered a chronic process that can go on for months to years before any symptoms are felt. The knee, ankle and elbow are the most commonly affected joints. OCD is a relatively rare problem, likely affecting far less than 1 percent of the population.
The age group that is most frequently affected is adolescents, ages 12 to 19.
Signs and Symptoms
Not all OCDs cause signs or symptoms (i.e. you may not know anything is wrong with the knee for much of the time), but can include knee pain, usually worse with increased activity, knee swelling, and possibly clicking and popping sensations. These may be preceded by a small injury that seemed to get better on its own.
The signs and symptoms of an acute injury to cartilage, on the other hand, are more obvious. There is usually a known twisting or contact injury to the knee, with rapid knee swelling and difficulty putting weight on the extremity. There may also be a sensation of clicking and locking of the involved joint.
Children with growth remaining in their knee (boys below age 16 and girls below age 14) will often be treated without surgery. Resting from impact activities (like running and jumping) is recommended for at least 3 months. Many physicians will also recommend crutches, bracing, and or casting.
However, if the OCD does not heal, or if it is “unstable” or threatening to break off when it is first discovered, surgery may be required.
If your doctor has recommended that you or your child modify activity, all activities that involve running or jumping should be avoided. These include activities and sports like soccer, basketball, lacrosse, baseball, tennis, volleyball, softball, racket sports, gymnastics, and dance. Safer alternatives that your doctor may allow include swimming, biking, and yoga.
The surgical choices to treat OCD depend on whether the OCD is firmly in place (stable) or threatening to loosen or dislodge (unstable). The following are a few examples of the many surgeries that are currently available to treat OCD.
- If the OCD is stable, the goal of the surgery is to help the OCD heal. This is most often done arthroscopically, with small incisions assisted by camera and small tools. A small pin is used to make drill holes to help encourage blood to flow to the area to heal the bone and cartilage.
- If the OCD is unstable, the point of the surgery is to make it firm or stable. A screw or dart may be used to hold the OCD in place to help it heal.
- If the bone and cartilage have broken off, and cannot be fixed, the goal of surgery is to place new cartilage in the hole.
- This can be done by ‘microfracture’, or stimulation of the bone, to make new scar tissue that acts like cartilage.
- Cartilage and bone may be moved from an area of the knee that does not need it, this is called osteochondral transplantation, or ‘OATS’. Cartilage and bone from a cadaver may alternatively be used to fill the hole.
- Lastly, the patient’s own cartilage may be sent to a lab and used to grow new cartilage that may be put back into the patient a few months later. This is called autogenous chondrocyte implantation, or ‘ACI’.
What is the difference between X-Ray and MRI to look at OCD?
X-Ray looks at bone. If the OCD involved the bone (which is under the cartilage), then the OCD will show up on X-Ray. There are special X-Ray views that your doctor may order to best see the OCD.
If the OCD does not show up on X-Ray, it may be because it only involves the cartilage. In this case, MRI scan will best show the OCD. MRI will also give more detail about the OCD, and may show whether the OCD is firmly in place (‘stable’) or not (‘unstable’), and whether it is healing or not.
Can OCD’s come back?
Do OCD’s run in families?
There are some reports of families that have many cases of OCD. However, most patients with OCD do not have family members with OCD’s, so there is not thought to be a strong genetic or family disposition for OCD.
If I have an OCD of my knee, what is the chance that I will have an OCD of another joint?
OCD of the knee is thought to be bilateral, or in both knees, about 1 out of 4 times. However, there is no known link between OCD of the knee and OCD of other joints.
At a Glance
Dr. Brian Waterman, MD
- Chief & Fellowship Director, Sports Medicine, Wake Forest
- Team Physician, Wake Forest University, Chicago White Sox
- Military affiliation/Decorated military officer and surgeon
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