Sickle Cell Anemia

Topic updated on 03/01/14 9:00am
  • Sickle cell disease is a genetic disorder of hemoglobin synthesis that occurs in two phenotypes            
    • sickle cell anemia
      • sickle cell anemia involves the presence of two abnormal hemoglobin S alleles 
      • more severe form 
    •  sickle cell trait
      • sickle cell trait involves a single copy of the abnormal hemoglobin gene
      • usually asymptomatic
      • increased risk of sudden-death with exertion 
        • due to collapse
        • responds early to oxygen, rest, hydration
      • more common 
  • Epidemiology
    • approximately 2 million Americans carry the sickle cell gene
      • 1 in 12 African Americans  
  • Pathophysiology
    • under low oxygen conditions the affected blood cells become "sickle shaped"  and are unable to pass through vessels efficiently   
  • Orthopaedic manifestations
    • sickle cell crisis (see below)
    • osteomyelitis
    • septic arthritis
    • osteonecrosis of femoral and humeral heads
    • bone infarcts 
    • growth retardation / skeletal immaturity
    • dactylitis (acute hand / foot swelling) 
Imaging General
  • Radiographs
    • recommended 
      • AP and lateral standard of involved area
    • findings
      • bone infarcts common 
      • biconcave "fishtale" vertebrae 
  •  MRI
    •  recommended for differentiating bone infarction from osteomyelitis
      • obtain gadolinium enhanced T1 sequences which will identify infection
  • Bone Scan 
    • helps differentiate infarct from infection
Studies General 
  • Labs
    • serum 
      • CBC, ESR, CRP 
        • may be elevated in both osteomyelitis and sickle cell crisis
    • joint aspiration and culture
      • may be necessary to determine if diagnosis is osteomyelitis or sickle cell crisis 
Sickle Cell Crisis
  • Presentation
    • severe bone pain 
    • usually begins near age 2-3 years
    • caused by substance P
    • may lead to bone infarcts
  • Treatment
    • nonoperative
      • hydroxyurea provides
        • pain relief during bone crisis
  • Introduction
    • often in diaphysis
    • organism
      • increased incidence of salmonella (may spread from gallbladder infection)but staph aureus is still the most common 
        • staph aureus is the most common cause of osteomyelits in all children, including those with sickle cell disease
        • salmonella osteomyelitis occurs most commonly in children with sickle cell disease, but is still less common than Staph aureus in these patients 
  • Imaging
    • radionuclide bone scan and radionuclide bone marrow scan can differentiate bone infarct from osteomyelitis 
      • osteomyelitis: normal marrow uptake, abnormal bone scan
      • infarct: decreased marrow uptake, abnormal bone scan
  • Evaluation
    • aspirate and culture to differentiate from a bone infarct
Septic arthritis
  • Sickle cell patients are susceptible to infection due to  
    • hyposplenia
    • sluggish circulation
    • decreased opsonization of bacteria
  • Presentation
    • bone pain
    • fever
  • Labs
    • elevated CRP and ESR
  • Studies
    • aspirate joint and culture to identify organism
  • Treatment
    • irrigation & debridement
      • consider preoperative oxygenation and exchange transfusion prior to surgery
Avascular Necrosis of Femoral Head
  • Osteonecrosis of the femoral head 
    • can be bilateral in sickle cell disease
  • Presentation
    • hip pain with weight bearing 
  • Treatment
    • Nonoperative
      • partial weight bearing and range of motion 
        • indications
          • initial treatment
    • Operative
      • total hip arthroplasty
        • indications
          • failed non operative 
          • intractable pain
        • outcomes
          • results of total joint arthroplasty are poor due to ongoing remodeling of bone


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Qbank (5 Questions)

(OBQ13.23) You are the team physician for a collegiate football team and receive weekly injury reports from the athletic trainer. All players with sickle-cell trait are listed at the bottom to remind all on-field personnel that they may need which of the following? Topic Review Topic

1. Oxygen supplementation and oral or IV hydration
2. Additonal layers of warm clothes
3. Increased pain medication
4. Avoidance of non-steroidal anti-inflammatory medicines
5. Days of rest due to increased joint pain

(OBQ12.39) A 28-year-old African-American male with a history of Sickle Cell Disease complains of progressive left hip pain for the past two years. He denies any causative injuries. His images are shown in Figures A and B. Which of the following mechanisms is most likely responsible for his symptoms? Topic Review Topic
FIGURES: A   B        

1. Blood disorder due to abnormal hemoglobin S alleles
2. Progressive slippage of physis though the hypertrophic zone
3. Osteomyelitis most likely due to Salmonella species
4. Accumulation of glycosaminoglycan breakdown products
5. COL5A1 or COL5A2 mutation

(OBQ11.77) A 3-year-old African-American child presents with irritability, fever, and a warm, swollen leg. Imaging shows an area concerning for osteomyelitis and trans-cortical biopsy reveals multiple Salmonella species. This child most likely also has which of the following conditions? Topic Review Topic

1. Osteogenesis imperfecta
2. Child abuse
3. Thalassemia
4. Sickle cell anemia
5. Renal failure

(OBQ09.94) Hematogenous osteomyelitis caused by Salmonella is most common in which of the following patient populations? Topic Review Topic

1. Neonates
2. Intravenous drug abusers
3. Patients with sickle cell disease
4. Patients with chronic kidney failure requiring dialysis
5. Patients with puncture wounds through athletic shoes

(OBQ06.42) A 12-year-old boy with sickle cell anemia complains of 24 hours of pain in the right thigh. He denies any traumatic injury. The right leg has tenderness with palpation of the mid-thigh. The patient's temperature is 100.2 degrees F, and ESR is 45. Radiographs of the femur are unremarkable. A radionuclide bone scan demonstrates abnormal uptake in the mid-femur. A radionuclide bone marrow scan demonstrates decreased uptake within the marrow. Which of the following is the best step in management? Topic Review Topic

1. Symptomatic care for his pain with NWB crutches, intravenous hydration, and consultation with hematology
2. Steroid injection of the quadriceps
3. Two weeks of an oral cephalosporin and follow-up radiographs
4. Bone biopsy for culture and intravenous antibiotics
5. Surgical debridement, culture, and intravenous antibiotics



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