Osteochondritis dissecans is a joint condition in which bone underneath the cartilage of a joint dies due to lack of blood flow. This bone and cartilage can then break loose, causing pain and possibly hinder joint motion.
Osteochondritis dissecans occurs most often in children and adolescents. It can cause symptoms either after an injury to a joint or after several months of activity, especially high-impact activity such as jumping and running, that affects the joint. The condition occurs most commonly in the knee, but also occurs in elbows, ankles and other joints.
Doctors stage osteochondritis dissecans according to the size of the injury, whether the fragment is partially or completely detached, and whether the fragment stays in place. If the loosened piece of cartilage and bone stays in place, you may have few or no symptoms. For young children whose bones are still developing, the injury might heal by itself.
Surgery might be necessary if the fragment comes loose and gets caught between the moving parts of your joint or if you have persistent pain.
However, affected people may experience pain, weakness and/or decreased range of motion in the affected joint if the cartilage and bone travel into the joint space. Although osteochondritis dissecans can affect people of all ages, it is most commonly diagnosed in people between the ages of 10 and 20 years.
Osteochondritis dissecans occurs most commonly in children and adolescents between the ages of 10 and 20 who are highly active in sports.
Osteochondritis dissecans can increase your risk of eventually developing osteoarthritis in that joint.
The signs and symptoms of osteochondritis dissecans vary from person to person. If the piece of cartilage and bone remain close to where they detached, they may not cause any symptoms. However, affected people may experience the following if the cartilage and bone travel into the joint space:
- Pain. This most common symptom of osteochondritis dissecans might be triggered by physical activity — walking up stairs, climbing a hill or playing sports.
- Swelling and tenderness. The skin around your joint might be swollen and tender.
- Joint popping or locking. Your joint might pop or stick in one position if a loose fragment gets caught between bones during movement.
- Joint weakness. You might feel as though your joint is "giving way" or weakening.
- Decreased range of motion. You might be unable to straighten the affected limb completely.
Although osteochondritis dissecans can develop in any joint of the body, the knee, ankle and elbow are most commonly affected. Most people only develop the condition in a single joint.
In most cases, the exact underlying cause of osteochondritis dissecans is not completely understood. Scientists suspect that it may be due to decreased blood flow to the end of the affected bone, which may occur when repetitive episodes of minor injury and/or stress damage a bone overtime. The reduced blood flow to the end of the affected bone might result from repetitive trauma — small, multiple episodes of minor, unrecognized injury that damage the bone. There might be a genetic component, making some people more inclined to develop the disorder.
In some families, osteochondritis dissecans is caused by changes (mutations) in the ACAN gene. In these cases, which are referred to as familial osteochondritis dissecans, the condition generally affects multiple joints and is also associated with short stature and early-onset osteoarthritis. The ACAN gene encodes a protein that is important to the structure of cartilage. Mutations in this gene weaken cartilage, which leads to the various signs and symptoms of familial osteochondritis disssecans.
Adolescents participating in organized sports might benefit from education on the risks to their joints associated with overuse. Learning the proper mechanics and techniques of their sport, using the proper protective gear, and participating in strength training and stability training exercises can help reduce the chance of injury.
During the physical exam, your doctor will press on the affected joint, checking for areas of swelling or tenderness. In some cases, you or your doctor will be able to feel a loose fragment inside your joint. Your doctor will also check other structures around the joint, such as the ligaments.
Your doctor will also ask you to move your joint in different directions to see if the joint can move smoothly through its normal range of motion.
Your doctor might order one or more of these tests:
- X-rays. X-rays can show abnormalities in the joint's bones.
- MRI. Using radio waves and a strong magnetic field, an MRI can provide detailed images of both hard and soft tissues, including the bone and cartilage. If X-rays appear normal but you still have symptoms, your doctor might order an MRI.
- CT. This technique combines X-ray images taken from different angles to produce cross-sectional images of internal structures. CT scans allow your doctor to see bone in high detail, which can help pinpoint the location of loose fragments within the joint.
The prognosis after different treatments varies and is based on several factors which include the age of the patient, the affected joint, the stage of the lesion and, most importantly, the state of the growth plate. It follows that the two main forms of osteochondritis dissecans are defined by skeletal maturity. The juvenile form of the disease occurs in open growth plates, usually affecting children between the ages of 5 and 15 years. The adult form commonly occurs between ages 16 to 50, although it is unclear whether these adults developed the disease after skeletal maturity or were undiagnosed as children.
The prognosis is good for stable lesions (stage I and II) in juveniles with open growth plates; treated conservatively—typically without surgery—50% of cases will heal. Recovery in juveniles can be attributed to the bone's ability to repair damaged or dead bone tissue and cartilage in a process called bone remodeling. Open growth plates are characterized by increased numbers of undifferentiated chondrocytes (stem cells) which are precursors to both bone and cartilaginous tissue. As a result, open growth plates allow for more of the stem cells necessary for repair in the affected joint. Unstable, large, full-thickness lesions (stage III and IV) or lesions of any stage found in the skeletally mature are more likely to fail non-operative treatment. These lesions offer a worse prognosis and surgery is required in most cases.
The primary aim of treatment for osteochondritis dissecans is to restore normal function of the affected joint, relieve pain and prevent osteoarthritis. Treatment for the condition varies depending on many factors including the age of the affected person and the severity of the symptoms. In children and young teens, osteochondritis dissecans often heals overtime without surgical treatment. These cases are often managed with rest and in some cases, crutches and/or splinting to relieve pain and swelling.
If non-surgical treatments are not successful or the case is particularly severe (i.e. the cartilage and bone are moving around within the joint space), surgery may be recommended. Following surgery, physical therapy is often necessary to improve the strength and range of motion of the affected joint.
Initially, your doctor will likely recommend conservative measures, which might include:
- Resting your joint. Avoid activities that stress your joint, such as jumping and running if your knee is affected. You might need to use crutches for a time, especially if pain causes you to limp. Your doctor might also suggest wearing a splint, cast or brace to immobilize the joint for a few weeks.
- Physical therapy. Most often, this therapy includes stretching and range-of-motion exercises and strengthening exercises for the muscles that support the involved joint. Physical therapy is commonly recommended after surgery, as well.
If you have a loose fragment in your joint or if conservative treatments don't help after four to six months, you might need surgery. The type of surgery will depend on the size and stage of the injury and how mature your bones are.
- Mayo Clinic