Avascular necrosis of hip

Background

Traumatic and nontraumatic causes can lead to an insult to the blood supply of the joint. The ischemia causes death of osteocytes and bone marrow that leads to necrosis and eventual collapse of the dead segment.

Kupe MD. Hip Fracture. http://drkupe.blogspot.com/2011/03/hip-fracture.html. Accessed July 31, 2016.
Plain XR Osteonecrosis Femur by JMarchn(own work)
MRI Osteonecrosis Femur by JMarchn (ownwork)

Epidemiology

  • Estimate of 10,000 to 20,000 new cases per year
  • Responsible for about 10% of all total hip replacements
  • Patients typically diagnosed before 40 years of age

Etiologies[1]

Traumatic causes

Non-traumatic causes

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

Hip pain

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

Management

  • Nonsurgical
    • Considered ineffective at stopping progression of ischemia
    • Bedrest, limit weightbearing, pain control
  • Medications
    • Bisphophonates, vasodilators, and anticoagulants have been used but efficacy has not yet been proven
  • Surgical
    • Total Join Replacement
    • Unfortunately, patients with osteonecrosis have an increased failure rate of the procedure.
  • Ongoing research for treatment
    • Joint preserving operations, Bone marrow decompression therapy, vascularized and nonvascularized bone grafts, Bone marrow grafting, and Osteotomy

Disposition

It is vital to order medical and orthopedic referrals for evaluation of comorbidities and evaluation of joint in the emergency department.

  • Progression to subchondral collapse if the diagnosis is missed and untreated
    • 67% in asymptomatic patients
    • Greater than 85% in symptomatic patients
  • In one study by the American Academy of Orthopaedic Surgeons, early detection and treatment with core decompression has shown to prevent the need for total hip replacement.

See Also

References

  1. *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.