Osteochondritis Dissecans in the Knee
Many activities place repetitive stress on the legs, more specifically the knees. Knees are extremely vulnerable to overuse injuries, as well as acute injuries, from stresses brought against them. When a young patient presents with generalized or anterior knee pain, and there aren’t any definitive abnormalities after examination, Osteochondritis Dissecans (OCD) should be considered.
Definition
Osteochondritis Dissecans is a condition in which a section of articular cartilage and its underlying bone slowly separates from the surrounding bone. This condition is painful and can do significant damage to the undersurface of the knee. The pain intensifies when the bone separates because at this time you have bone floating around the knee, and in and out of the joint space.
Causes/Symptoms
The usual sufferers of OCD are adolescents, young adults, and men. The affected site is usually the medial femoral condyle. Half of the time, patients present with some sort of trauma in the recent history. Patients may present with swelling , locking, or pain to additional sites. There’s usually limitation with movements and flexibility, and nearly always some quadriceps atrophy.
A good test to reveal OCD is Wilson’s Test, where the knee is flexed to 90 degrees and the tibia is rotated internally, and then the knee is extended. Pain can usually be seen at about 70 degrees of flexion around the medial femoral condyle. Sometimes patients have deformities of the knee, such as genu valgum (knock-knees), or genu varum (bow-leg).
Additional Studies
If a patient’s findings include any of the following: joint swelling, diminished thigh girth, or a positive Wilson’s Test, then additional study is indicated. Usually, radiographic study is the next in line to try and solve the problem. The specific X-ray that usually can locate signs of OCD is the Tunnel View X- ray, because it best shows the intercondylar notch, the region of most OCD lesions. Other tests that can be helpful are MRIs, Arthroscopy, and Arthrography.
Treatment
If the problem is recognized and diagnosed early, immobilization by cast or soft knee immobilizer may be prescribed along with 4 to 6 weeks of rest. The leg can be casted in a way that protects against tibiofemoral contact. Once X-rays show good position and healing, the doctor will allow more activity to proceed. The younger the patient and the shorter the duration of symptoms, the more satisfactory the healing will be. In the older patient, or the more chronic the lesion, surgery is often the treatment of choice. If there’s a loose bone in the knee, surgery is needed to remove it. For the lesion which is still attached, there are a few alternatives available, such as curettage and drilling, simple drilling, and pinning in place what’s left. Sometimes the surgery can be done arthroscopically, but regardless of the surgical method, cast immobilization for up to 8 weeks will be necessary. If pins are used during the operation, then a second operation will be later performed to remove the pins.
Prognosis
Older people tend to have a lot more trouble than younger people with this condition. In many cases, if the lesion is treated early enough, people recover very well. The problem with many older patients is that they sometimes already have degenerative joint changes before surgery. With younger, skeletally mature people, the outcome is often a lot better. The overall prognosis is generally good to excellent, depending on the size of the lesion and time of detection.