Osteonecrosis

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Osteonecrosis

1. Demographics -

There are 2 types of osteonecrosis that may affect

the knee in adults. Osteonecrosis

may affect the medial or lateral femoral condyles

(usually medial) or the medial tibial plateau. Risk

factors include ETOH overuse, smoking, corticosteroid use, hemoglobinopathies

such as sickle cell disease, systemic lupus erythematosus

(regardless of steroid use), and radiation therapy.

ETOH/corticosteroids may increase fat cell size leading to compression of small

osseous vessels. Sickle cells sludge inside the vessels leading to vascular

compromise.

Spontaneous Osteonecrosis

of the Knee is seen in the elderly and usually occurs in the

medial femoral condyle after trauma or overuse. It

can be diagnosed by bone scan or MRI even before X-rays are abnormal.

Plain radiograph of the knee is unremarkable.

MRI demonstrates a large area of bone edema located in the medial femoral condyle in this 68 year old lady with spontaneous osteonecrosis.

Osteochondritis dissecans is a

form of osteonecrosis that typically occurs in young

men related to trauma. It most often occurs in the medial femoral condyle and often results in an osteochondral

defect.

MRI of the knee shows a focal area of osteochondritis

dissecans in the medial aspect of the lateral condyle of the femur.

2. Symptoms - Both

types are characterized by significant pain and articular

swelling. The pain is usually worse with weight bearing and there may also be

night pain. The pain is usually of severe intensity.

3. Signs -

Examination usually reveals a swollen knee and tenderness along the femoral condyle. Synovial fluid will be noninflammatory.

4. Radiologic

Evaluation - Early in the course, the plain films will be

normal and the pain will seem out of proportion the mild or minimal changes of

osteoarthritis that may be there. Later on (months) the X-rays will show a

mottled, crescent shaped defect in the bone at the site of the infarct. Bone

scans are typically positive early although MRI is probably the most sensitive.

Screening protocols are available at some hospitals to minimize the cost of the

procedure.

5. Therapy -

Patients with small infarct (less than 2.3 cm2 in area) may not progress while

larger infarcts usually progress on to degenerative arthritis in the affected

compartment. Treatment is directed toward pain relief, ambulatory aids, and maintainance of quadriceps strength. Surgical treatment consists

of drilling the area to relieve pressure. If the process progresses, unicompartmental or total knee arthroplasty

is the usual treatment.

Much

Love,

Deanna

LUPUS

Serenity Prayer...

Lord, grant me the

serenity to accept the things I cannot change, the courage to change the things

I can, and the wisdom to hide the bodies of doctors I shot when they said,

You're perfectly healthy, it's all in your head "