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A 23 year old black man with sickle cell disease presented to hospital with a two year history of worsening groin pain and stiffness in both hips. He was admitted under orthopaedics after being referred by his general practitioner. No other joints were involved. The patient had no history of comorbidities associated with sickle cell disease and had restricted range of movement in both hips. A plain radiograph of the pelvis was obtained (fig 1 ). Results of a full blood count test showed a haemoglobin level of 90 g/L (reference range 135-180 g/L and a peripheral blood film showed sickle shaped cells, nucleated red blood cells, and cell fragments. Haemoglobin electrophoresis showed high levels of haemoglobin S (65%), and serum bilirubin was 17.1 [mu]mol/L. (reference range- 3-25 [mu]mol/L) Other laboratory tests were unremarkable.
Questions
1. What is the diagnosis and what are the differential diagnoses?
2. How is this condition assessed radiologically?
3. How is the condition managed?
Answers
What is the diagnosis and what are the differential diagnoses?
Short answer
The diagnosis is osteonecrosis of both femoral heads with secondary osteoarthritis of the hips. The differential diagnoses are primary osteoarthritis, inflammatory arthritides, rapidly progressive osteoarthritis, subchondral insufficiency fractures, and transient osteoporosis of the hip.
Discussion
Osteonecrosis of the femoral head results from an inadequate blood supply, which causes death of the osteocytes. It can be idiopathic, but known causes include:
Steroid use
Alcohol consumption
Disruption of arterial supply-for example, from pelvic trauma
Pelvic surgery
Lipid metabolism disorders
Coagulation disorders
Embolism-for example, due to sickle cell disease, Gaucher's disease, or dysbarism
Autoimmune disease
Ionising radiation
Cytotoxic agents.
Osteonecrosis of the femoral head typically affects people aged 20 to 40 years. A bilateral presentation is often seen, and men are more commonly affected. Within two years of the onset of osteonecrosis in one hip, the bilateral hip may be affected in about 55% of patients. Taking a detailed clinical history can identify any associated risk factors. In the early stages, patients may develop groin pain that can radiate to the knee or buttock on the same side of the body. Pain and restriction of movement may be the only symptoms, but gradually hip movement becomes limited, especially internal rotation. Radiographs show a localised area of...