Osteochondritis dessicans
From Medical-Wiki
The term Osteochondritis dissecans (OCD) refers to an osteochondral fracture. It is a form of osteochondrosis limited to the articular epiphysis. Both trauma and ischemia probably play a role in the process. The trauma may be in the form of direct insult as in an impaction fracture. It may also be in the form of repetitive microtrauma—an overuse syndrome.
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Injury process
The three stages of the process are important because they shed light on the mechanisms of injury.
- In the first stage, thickened and edematous intra-articular and periosteal soft tissues develop. There will sometimes be a development of mild osteoporosis in the metaphysis adjacent to the area of injury because of the active hyperemia.
- In the second stage, the epiphysis may begin to show fragmentation. It develops an irregular contour. Adding to the degenerative process are a loss of vasculature because of thrombi and the microfractures of the trabeculated bone.
- As the bone heals in the third stage, granulation tissue replaces the necrotic areas. In those areas, structure is lost, and there is a further flattening of the articular surface.
If injury to the articular surface allows a flooding of synovial fluid into the epiphysis, a subchondral cyst can form. This further increases joint pressure and prevents healing. The knee, elbow, ankle, tarsal navicular, hip, shoulder and wrist can all undergo this process. [1]
Categorization
OCD may be broken into two categories according to age, juvenile, 15 years old and younger, and adult, older than 15. However, the classification also relates to the nature of the pathology. Juvenile refers to smaller lesions, and adult refers to lesions that are not only larger but may have also fragmented. These fragments are sometimes referred to as “bone chips.”
This latter problem is often complicated by the reality that imaging techniques are incapable of accurately revealing anatomy and only direct visualization through surgery or laparoscopy will do so. [2]
Clinical presentation
Joint locking, crepitus, joint pain, and joints “giving way” are the most common complaints noted by patients with OCD.
Diagnosis
Juvenile versus adult
There has been an evolution about OCD over the past few years. For a time, only the adult form of the disease was recognized. To carry a diagnosis of OCD, patients basically had to have loose bodies in their joints. Now, it is recognized that the juvenile form of OCD is far more subtle than was earlier appreciated. Thus, radiographs alone will often miss juvenile forms of the disease and even some adult forms that are non-fragmented and centrally located. [3]
Physical findings
Examination may reveal joint line tenderness and effusion. If x-rays are unrevealing of an etiology of a patient’s complaints, MRI and CT scanning may be of assistance. However, it is judicious to consider referring a patient to an orthopedic surgeon with experience with OCD before ordering these tests.
As noted above, it is often times apparent that some form of intervention will be required and further non-invasive imaging serves no function. [4]
Treatment
The treatments are different depending upon the category of the OCD, but there is some difficulty differentiating between the two categories because age alone is only an approximation of what kinds of pathology should make up an injury. There is also difficulty differentiating OCD from a variety of other similar processes.
There are a huge number of procedures used to address the abnormal anatomy associated with OCD. There are really no large studies comparing success rates for these procedures, in part because they are often tailored to the individual abnormalities. [5]
