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.

Epidemiology

Est 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

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

Management

Medical and orthopedic referrals for evaluation of comorbidities and evaluation of joint should be made in the emergency department.

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.
On going research for treatment
- Joint preserving operations, Bone marrow decompression therapy, vascularized and nonvascularized bone grafts, Bone marrow grafting, and Osteotomy

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.

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