A 21-year-old man comes to the office requesting a refill of an opioid medication for new-onset left hip pain. The pain started 3 weeks ago and was initially only with weightbearing, but has progressively worsened and is now present at rest and overnight. He has no history of trauma. Medical history is notable for sickle cell disease with several hospitalizations for acute pain crisis. His last hospitalization was 3 months ago. The patient has been taking some leftover opioid pain medications from that hospitalization, in addition to regularly scheduled folic acid and hydroxyurea. He is sexually active with a new female partner. The patient does not use alcohol, tobacco, or illicit drugs. His temperature is 37.2 C (99 F), blood pressure is 100/70 mm Hg, pulse is 80/min, and respirations are 16/min. Physical examination reveals no local tenderness, but there is restriction of abduction and internal rotation of the left hip. The right hip and other joints are normal. Hip x-rays and erythrocyte sedimentation rate are normal. Which of the following is the most likely diagnosis?
Avascular necrosis | |
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CRP = C-reactive protein; ESR = erythrocyte sedimentation rate. | |
This patient has features typical of osteonecrosis (aseptic necrosis) of the femoral head, including progressive hip pain, limited internal rotation and abduction, unremarkable x-rays (can remain normal for months), and normal inflammatory markers (eg, erythrocyte sedimentation rate [ESR]). Osteonecrosis is caused by occlusion of end arteries supplying the femoral head, leading to necrosis and collapse of the periarticular bone and cartilage.
Osteonecrosis is common in patients with sickle cell disease due to disruption of microcirculation in the bone by sickling as well as increased intraosseous pressure due to bone marrow hyperplasia. The femoral head has 2 main sources of blood - the ascending arteries and the foveal artery, which lies within the ligamentum teres. The foveal artery is patent early in life, but may become obliterated in older patients. For this reason, aseptic necrosis of the femoral head is uncommon in children but the risk rises in older patients.
(Choice A) Osteomyelitis is a recognized complication of sickle cell disease, and is usually due to Staphylococcus aureus or Salmonella. It is most common in children, often multifocal, and typically accompanied by fever, malaise, and elevated ESR.
(Choice B) Neisseria gonorrhoeae can cause acute purulent arthritis (usually without associated skin lesions or fever). However, involvement of the distal large joints (eg, knees, wrists, ankles) is more common, and it would usually be associated with elevated ESR.
(Choice C) Features that suggest drug-seeking behavior include "lost" or "stolen" medication, premature refill requests, and pain inconsistent with examination findings or known pathology. This patient's pain is easily explainable by osteonecrosis, which is a recognized complication of his underlying disease.
(Choice E) Slipped capital femoral epiphysis (SCFE) is characterized by pain and altered gait. Obesity is an important risk factor. SCFE most often occurs in early adolescence and is usually visible on x-rays.
Educational objective:
Osteonecrosis (aseptic necrosis) of the femoral head is a common complication of sickle cell disease and presents with hip pain, reduced range of motion, and normal findings on initial x-rays. It is due to occlusion of end arteries supplying the femoral head, leading to necrosis and collapse of the periarticular bone and cartilage.