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.
Pathophysiology – osteochondritis dissecans
Once a lesion is present, it typically progresses through 4 stages unless appropriately treated.
- Stage I consists of a small area of compression of subchondral bone.
- Stage II consists of a partially detached osteochondral fragment. A radiograph of the bone may reveal a well-circumscribed area of sclerotic subchondral bone separated from the remainder of the epiphysis by a radiolucent line.
- Stage III lesions are the most common and consist of a completely detached fragment that remains within the underlying crater bed.
- Stage IV lesions consist of a completely detached fragment that is completely displaced from the crater bed. This is also termed a loose body.
Causes of osteochondritis dissecans
The exact cause is unknown, but they may include:
Ischemia: a restriction of blood supply starves the bone of essential nutrients. The restricted blood supply is usually caused by some problems with blood vessels or vascular problems. The bone undergoes avascular necrosis, a deterioration caused by a lack of blood supply. Ischemia usually occurs in conjunction with a history of trauma.
Genetic factors: OCD sometimes affects more than one family member. This may indicate an inherited genetic susceptibility.
Repeated stress to the bone or joint: this can significantly increase the risk of developing OCD. Individuals who play competitive sports are more likely to regularly stress their joints.
Other factors may be weak ligaments or meniscal lesions in the knee.
Risk factors
Repetitive throwing / valgus stress and gymnastics/weight bearing on upper extremity
- Valgus stress / compressive force on the vulnerable chondroepiphysis of the radiocapitellar joint in skeletally immature patients is supported as the etiology for OCD of the capitellum
- Ankle sprain/instability
- In the talus, 96% of lateral lesions and 62% of medial lesions were associated with direct trauma
- Competitive athletics
- Family history: epiphyseal dysplasia has been postulated as a subset of OCD
Symptoms of osteochondritis dissecans
The symptoms of osteochondritis dissecans include:
- Pain in the joint, especially after activity
- Swelling of the affected joint
- Decreased joint movement, such as not being able to fully extend your arm or your leg
- Stiffness after resting
- A joint that “sticks” or “locks” in one position
- A clicking sound when you move the joint
- The weakening of the joint that makes it feel like it is “giving way”
These are all clues that you may have osteochondritis dissecans. See your doctor if you have any of these symptoms, or if you have persistent pain or soreness in a joint.
Complications
A nonunion of the OCD fragment may occur and progress to dissociation, leading to intra-articular loose body symptoms. This, in turn, may lead to a type of reconstructive procedure such as OATS or ACI (see Surgical Intervention in Acute Phase). Regardless of treatment, degenerative articular changes may develop over time.
Diagnosis
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 whether the joint can move smoothly through its normal range of motion.
Imaging tests
Your doctor might order one or more of these tests:
X-rays. X-rays can show abnormalities in the joint’s bones.
Magnetic resonance imaging (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.
Computerized tomography (CT) scan. 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 the bone in high detail, which can help pinpoint the location of loose fragments within the joint.
How is it treated?
OCD often heals on its own, especially in children who are still growing. However, other cases might require treatment to restore joint function and reduce your risk of developing osteoarthritis.
Nonsurgical treatment
Sometimes, the affected joint just needs to rest. Try to avoid doing strenuous or high-impact activities for a few weeks to give your joint time to heal. Your doctor might also recommend using crutches or wearing a splint to prevent your joint from moving too much.
Conservative treatment entails resting from strenuous or high-impact activity, to give the joint time to heal. In some cases, your doctor might recommend using crutches or splinting the joint to allow it to rest more fully.
Surgical treatment
If your symptoms don’t improve after four to six months, you might need surgery. Your doctor will also likely recommend surgery if you have a loose bone or cartilage fragments in your joints.
There are three main approaches when it comes to surgery for OCD:
Drilling. Your doctor will use a drill to make a small hole in the affected area. This encourages new blood vessels to form, increasing blood flow to the area and helping it heal.
Pinning. This involves inserting pins and screws to hold the lesion of a joint in place.
Grafting. Your doctor takes bone or cartilage from other areas of your body and places it in the damaged area, grafting new bone or cartilage onto the damaged area.
After surgery, you’ll probably need to use crutches for about six weeks. Your doctor might also recommend doing physical therapy for several months to help you regain strength. You should be able to start returning to your usual activity level in about five months.
Is it possible to prevent osteochondritis dissecans?
It is only possible to prevent osteochondritis dissecans by preventing trauma or injury to the affected joint.