Avascular necrosis of hip

Background

Can be simplified to traumatic and nontraumatic causes that lead to an insult to the blood supply to the bone. The ischemia causes death of osteocytes and bone marrow which will eventually lead to necrosis and collapse of the dead segment.

Kupe MD. Hip Fracture. http://drkupe.blogspot.com/2011/03/hip-fracture.html. Accessed July 31, 2016.

Etiologies

• Traumatic causes
  • Femoral neck fracture/Dislocation

• Non-traumatic causes
  • Use of Corticosteriods, Alcohol, Tobacco
  • Systemic Lupus Erythematosus
  • Sickle Cell Disease
  • Chronic Kidney Disease
  • Pancreatitis
  • Radiation therapy
  • HIV
  • Caisson Disease aka Dysbarism
  • Legg-Calve-Perthes disease
  • Idiopathic

Clinical Features

• Limp
• Limited range of motion of joint, both active and passive
• Pain: Knee, Thigh, and/or Groin
• Wasting of local musculature
• Asymmetric leg length

Differential Diagnosis

• Acute Fracture
• Acute Disclocation
• Septic Joint
• Synovitis
• Musculoskeletal insult

Evaluation

• Plain XR is poorly sensitive in early stages, as low as 41%
  • AP and Frog leg views
• MRI ~90% sensitivity and specificity
  • Best test
• Bone Scan aka Bone Scintigraph
  • May show evidence of early bone ischemia

Disposition

• Initial supportive care until later stages of disease
• Orthopedic consultation for repeat imaging and risk stratification for surgical treatment

References

• JONES PHD, L. C. AND MONT MD, M. A. Osteonecrosis (avascular necrosis of bone) In-text: (Jones PhD and Mont MD) Your Bibliography: Jones PhD, Lynne C and Michael A Mont MD. "Osteonecrosis (Avascular Necrosis Of Bone)". UpToDate. N.p., 2016. Web. 31 July 2016.
• Kelly JD et al. Femoral head avascular necrosis treatment & management. Aug 16, 2015. http://emedicine.medscape.com/article/86568-treatment#showall.
• Stoica Z et al. Imaging of Avascular Necrosis of Femoral Head: Familiar Methods and Newer Trends. Curr Health Sci J. 2009 Jan-Mar; 35(1): 23–28.
• Wainwright A. Legg-Calve-Perthes disease diagnostic tests - Epocrates online. Epocrates. https://online.epocrates.com/diseases/75134/Legg-Calve-Perthes-disease/Diagnostic-Tests. Accessed July 31, 2016.