A Closer Look at Avascular Necrosis of the Hip
Avascular necrosis accounts for approximately 10% of all total hip arthroplasties performed in the United States. Avascular necrosis can be caused when decreased blood flow is caused at the femoral head, which then leads to cellular death, fracture, and eventual collapse of the articular surface. Ultimately, of individuals who are diagnosed with AVN, there is a collapse rate of 67% in asymptomatic and 85% in symptomatic patients.1,2
Who is at Risk?
Moyer-Angeler and colleagues performed a review of the indirect and direct risk factors for the eventual development of AVN and found the following results:1
| Direct Risk Factors | Indirect Risk Factors |
|---|---|
| Femoral Head/Neck Fracture | Chronic Corticosteroid Use |
| Hip Dislocation | Excessive Smoking and/or Alcohol Use |
| Slipped Capital Femoral Epiphysis | Coagulation Disorders |
| Radiation Therapy | Hemoglobinopathies |
| Sickle Cell Disease | Dysbaric Phenomena |
| Caisson Disease | Autoimmune Diseases |
| Myeloproliferative Disorders | Hyperlipidemia |
What is the Clinical Presentation?
Clinical presentation may include subjective complaints like asymptomatic pain in early stages, and groin pain radiating to the knee or ipsilateral buttock. X-ray imaging may be negative in early stages as well.1,3,4
The physical examination may reveal painful, global restrictions in active and/or passive range of motion (especially internal rotation). Bilateral symptoms are also common, and are reported in 70% of cases. The patient may also present with an antalgic gait pattern.
Symptoms may be distributed as follows:
- Hip Region (97%)
- Groin (93%)
- Buttock (34%)
- Greater Trochanter (9%)
- Referred Pain (77%)
- Knee (68%)
- Anterior Thigh (36%)
- Lower Leg (18%)
- Low Back (8%)
Pain from AVN is significantly more frequent in the knee and lower leg, but significantly less frequent in the lower back than pain from osteoarthritis.1,3,4
What About Special Testing?
The tables below show the accuracy of various diagnostic tests:7
| Hip Extension < 15 Degrees | ||||
|---|---|---|---|---|
| Reliability | Sensitivity | Specificity | +LR | -LR |
| N/A | 0.19 | 0.92 | 2.38 | .88 |
| Hip External Rotation < 60 Degrees | ||||
|---|---|---|---|---|
| Reliability | Sensitivity | Specificity | +LR | -LR |
| N/A | .38 | .73 | .48 | .85 |
| Pain with Internal Rotation | ||||
|---|---|---|---|---|
| Reliability | Sensitivity | Specificity | +LR | -LR |
| N/A | 0.13 | 0.86 | 0.93 | 1.01 |
Is Conservative Management Effective?
Unfortunately, based on the few studies available evaluating the effectiveness of conservative and physical therapy intervention, there is no evidence supporting the ability of these interventions to decrease symptoms or prevent disease progression.5,6 At present, the best options available for this patient population involves either total hip arthroplasty (see the video animation below) or core decompression. Having the ability to rule out/in this disorder is of utmost importance in order for the appropriate surgical intervention to be applied.
- Moya-Angeler J. Current concepts on osteonecrosis of the femoral head. WJO. 2015;6(8):590–13. doi:10.5312/wjo.v6.i8.590.
- Mankin HJ. Nontraumatic necrosis of bone (osteonecrosis). N Engl J Med 1992; 326: 1473-1479
- Roth A, Beckmann J, Bohndorf K, et al. S3-Guideline non-traumatic adult femoral head necrosis. Arch Orthop Trauma Surg. 2015;136(2):165-174. doi:10.1007/s00402-015-2375-7.
- Nakamura J, Konno K, Orita S, et al. Distribution of hip pain in patients with idiopathic osteonecrosis of the femoral head. Mod Rheumatol. July 2016:1-5. doi:10.1080/14397595.2016.1209830.
- Hong Y-C, Zhong H-M, Lin T, Shi J-B. Comparison of core decompression and conservative treatment for avascular necrosis of femoral head at early stage: a meta-analysis. Int J Clin Exp Med. 2015;8(4):5207-5216.
- Neumayr LD. Physical Therapy Alone Compared with Core Decompression and Physical Therapy for Femoral Head Osteonecrosis in Sickle Cell Disease: Results of a Multicenter Study at a Mean of Three Years After Treatment. J Bone Joint Surg Am. 2006;88(12):2573–11. doi:10.2106/JBJS.E.01454.
- Reiman et al. Diagnostic accuracy of clinical tests of the hip: a systematic review with meta-analysis. Br J Sports Med. 2012
