Osteochondritis dissecans, also called OCD, is the most common cause of a loose body or fragment in the knee and is usually found in young males between the ages of ten and twenty. While this word sounds like a mouth full, breaking down its Latin derivation to its simplest terms makes it understandable: “osteo” means bone, “chondro” means cartilage, “itis” means inflammation, and “dissecans” means dissect or separate. In OCD, a flap of cartilage with a thin layer of bone separates from the end of the bone. As the flap floats loosely in the joint, it becomes inflamed, painful and disrupts the normal function of the joint.
Typically, OCD is found in the knee joint of active young men who participate in sports which involve jumping or full contact. Although less common, it is also found in other joints such as the elbow.
Often, the exact cause of OCD is unknown. For a variety of reasons, blood flow to the small segment at the end of the bone is compromised and the weak tissue breaks away and becomes a source of pain in the joint. Long term, OCD can increase the risk of osteoarthritis in the involved joint.
To properly diagnose OCD a physician will consider onset, related activities, symptoms, medical history, and examine the joint involved for pain, tenderness, loss of strength and limited range of motion. Often, a referral to a specialist such as an orthopedic surgeon for further examination is necessary. Special tests may be employed to specifically detect a defect in the bone or cartilage of the joint such as:
Radiograph (X-ray) may be performed to assess the bones.
Magnetic Resonance Imaging (MRI) may be performed to assess bones and other soft tissues such as cartilage, ligaments, muscles and tendons.
The primary goal of treatment for OCD is to relieve pain, control swelling, and restore the complete function (strength and range of motion) of the joint. Treatment is dictated by the age of the patient and severity of the injury. Medications for pain and inflammation may be prescribed.
Young patients who are still growing have a good chance of healing with conservative treatment. Rest and physical therapy are the conservative treatments of choice. Rest entails avoiding any activity that compresses the joint such as jumping, running, twisting, squatting, etc. In some cases, using a splint, brace and crutches to protect the joint and eliminate full weight bearing, may be necessary for a few weeks. Physical therapy, either as a conservative or post operative treatment, involves restoring the range of motion with stretching exercises and improving the strength and stability of the joint through strengthening exercises. Modalities for pain and swelling such as heat, cold, electrical stimulation, ultrasound, compression devices may be employed depending on the age of the patient and severity of the problem.
Conservative treatment can often require 3 to 6 months to be effective. However, if it fails, arthroscopic surgery may be required to stimulate healing or reattach the loose fragment of cartilage and bone. In some cases if the defect is small, surgery involves filling in the defect with small bundles of cartilage. In other cases, the fragment is reattached directly to the defect using a small screw or bioabsorbable device. More recently, surgeons are using the bone marrow of the patient to repair the deficit by stimulating the growth of new tissue (bone marrow stimulation). In other cases, a plug of healthy tissue from the non-weight bearing surface of a patients knee is transplanted to the defect to stimulate healing (osteochondral autograft transplantation OATS). While there are many surgical options for OCD, an orthopedic surgeon will help the patient decide the most appropriate procedure based on age, size of defect, and other factors.
While prevention is not always possible, some measures can be taken to limit risk. For example, if a child playing sports has a father and older brother who had OCD, then it would be wise to consider the following: Avoid or make modifications for sports requiring constant jumping. Cross-train for a sport to avoid daily trauma (run one day and bike the next). Also, do not play the sport all year round (basketball in the fall/winter and baseball in the spring/summer). Seek the advice from an orthopedic or sports physical therapist to learn proper strength and conditioning techniques. Learn proper biomechanics of lifting, throwing, squatting, running, jumping and landing.
Sources: Mayo Clinic
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Paul J. Mackarey PT, DHSc, OCS is a Doctor in Health Sciences specializing in orthopaedic and sports physical therapy. Dr. Mackarey is in private practice and is an associate professor of clinical medicine at The Commonwealth Medical College.