Problem 11

Question 1

Etiologies for aseptic osteonecrosis of the femoral head

Answer 1

• trauma (intracapsular femoral neck fracture or dislocation of the hip which can interrupt blood supply)
• complication of allograft organ transplantation where we give steroids
• alcohol
• Dysbaric phenomena such as Caisson’s disease, sickle cell anemia, and Gaucher’s disease
• Gout and hyperuricemia, radiation, osteoporosis, hypophosphatemia, hyperparathyroidism, and connective tissue diseases.

Question 2

Pathophysiology of dysbaric phemomena

Answer 2

In sickle cell disease: thromboembolic mechanism is thought to occur. In sickle disease this would result from sludging of red cells.
Caisson’s disease this represents nitrogen bubbles.
In infiltrative disorders such as Gaucher’s disease, it is
thought that the circulation is encroached with subsequent compromise of nutrition to the osteocytes and marrow.

Question 3

a cause of ON in steroid treated patients and alcohol

Answer 3

Intravascular fat

Question 4

Risk factors

Answer 4

osteoporosis

osteomalacie

Question 5

ON diagnosis

Answer 5

The diagnosis of ON is made in a patient at high risk who has typical radiographic findings.
However, there is no “gold standard” in the diagnosis of early lesions. The history and physical exam are often non-specific, and radiographs are negative in early disease.
MRI has recently emerged as the most sensitive, specific, and widely used diagnostic tool in these cases.
Plain radiographs, bone scans, CT scans,
and tomograms have been used to diagnose osteonecrotic lesions. The accuracy of these tests done alone or in combination has not equaled MRI in comparative studies. However, bone scans are useful in early diagnosis. Plain radiographs have a role in diagnosing later stages and in following progression. Other tests may have a role in selective cases and in preoperative planning. Plain radiographs can be used to follow lesions once they appear radiographically, but this is relatively late in the course. Magnetic resonance imaging has superceded previous tests as the most accurate method of diagnosing lesions early and should be used in all symptomatic patients considered at high risk.

Question 6

What is the ttt

Answer 6

total hip arthroplasty
structural bone grafting
electrical stimulation
osteotomy
vascularized bone grafting