High Yield Topics

Hip Avascular Necrosis

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Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.
Title: 5-Minute Orthopaedic Consult, 2nd Edition
> Table of Contents > Hip Avascular Necrosis

Hip Avascular Necrosis
Ricardo A. Gonzales MD
Michelle Cameron MD
Basics
Description
  • AVN is osteonecrosis, or death of the bone.
    • All major joints can be affected.
    • In the pediatric population, this
      condition is called “Legg-Calvé-Perthes disease” and, in general, has a
      better prognosis than osteonecrosis in the adult.
  • AVN of the hip is osteonecrosis of the femoral head.
  • Synonyms: Osteonecrosis; Aseptic necrosis; Chandler disease
  • Classification:
    • Ficat and Arlet (1) described 4 stages:
      • Stage I: No changes on radiograph, changes noted on MRI
      • Stage II: Sclerotic or cystic changes on radiographs in the femoral head, no collapse
      • Stage III: Subchondral fracture, crescent sign on radiographs
      • Stage IV: Degenerative changes in the hip joint with involvement of the femoral head
    • Steinberg et al. (2) modification of the Ficat and Arlet classification (all stages except stage 0 + advanced degenerative changes):
      • Stage 0: Normal radiograph, normal bone scan
      • Stage I: Normal radiograph, abnormal bone scan
      • Stage II: Sclerosis or cyst formation in the femoral head (A = mild, <20%; B = moderate, 20–40%; C = severe, >40%)
      • Stage III: Subchondral collapse (crescent
        sign) without flattening (A = mild, <15%; B = moderate, 15–30%; C =
        severe, >30%)
      • Stage IV: Flattening of the head without
        joint narrowing or acetabular involvement (A = mild, <15% of surface
        and <2 mm of depression; B = moderate, 15–30% of surface or 2–4 mm
        of depression)
      • Stage V: Flattening of head with joint
        narrowing or acetabular involvement (A = mild; B = moderate; C = severe
        [acetabular involvement])
    • One of the most predictive findings on radiography or MRI is the actual size of the lesion (3).
General Prevention
  • Limited systemic corticosteroid use
  • Avoidance of alcohol abuse
  • Early fixation of femoral neck fractures or reduction of hip dislocations
Epidemiology
  • Most common in young adults 20–40 years old and in children 6–10 years old.
  • The average age of patients with osteonecrosis who require hip arthroplasty is 38 years (4).
  • The distribution between males and females is equal (4).
  • Patients with atraumatic osteonecrosis of one hip have a >50% chance of developing osteonecrosis of the contralateral side (5).
Prevalence
~2.5% of total hip replacements are performed for the diagnosis of AVN (6).
Risk Factors
  • Femoral neck fractures
  • Steroid use
  • Alcohol abuse
  • Hemoglobinopathies (e.g., sickle cell anemia)
  • Clotting abnormalities
  • Dysbarism (“bends”)
  • Ionizing radiation
  • Pancreatitis
  • Gout
Genetics
A genetic pattern may be related to a clotting disorder with protein S deficiency.
Etiology
  • Osteonecrosis is most commonly alcohol-related or induced by incremental and cumulative doses of corticosteroids (90%) (4).
    • Alcohol: The threshold of alcohol
      ingestion reported to be associated with osteonecrosis is the
      equivalent of 400 mL or more per week of 100% ethyl alcohol (~3 beers
      per day) (4).
    • Corticosteroids:
      • A total dose of 2,800 mg of oral prednisone over 4 months significantly increases the risk of bone infarction (7).
      • Some researchers believe that patients
        who have idiosyncratic reactions to steroids, with systemic changes
        such as acute weight gain or moon faces, have an increased risk of
        developing osteonecrosis.
  • Other causes include:
    • Traumatic injuries such as hip fractures
    • Subclinical clotting disorders
    • Exposure to atmospheric pressure variations
Associated Conditions
  • Hip fracture
  • Hemoglobinopathy
  • Alcohol abuse
  • Perthes disease
Diagnosis
Signs and Symptoms
  • Onset of pain in the hip without antecedent trauma
  • Pain is usually in the groin.
History
  • The patient often initially complains of vague pain in the groin for 4–6 months before evaluation.
  • Pain increases with internal rotation of the hip.
  • A high index of suspicion should exist in a young patient with hip pain and other risk factors.
Physical Exam
  • Look for groin pain with ROM of the hip (internal rotation), which is not typically tender with direct palpation.
  • The patient has a limp but a normal neurologic examination.
  • The combination of history and physical examination should lead to a suspicion of osteonecrosis of the hip.
Tests
Lab
  • Complete blood count
  • ESR
  • Coagulation profile (research tool at present)
Imaging
  • Plain radiographs, including AP and lateral projections of the hip
  • MRI of the hip is the single best test for diagnosing osteonecrosis of the hip (specificity, 98%) (8).
Pathological Findings
  • Although osteonecrosis has many possible
    causes, a common final pathway leads to the typical pathologic
    findings, including death of the osteoblast and osteocytes with empty
    lacunae in the trabecula of the necrotic area.
  • An area of sclerotic margin also commonly is present in the area of necrosis.
Differential Diagnosis
  • Fracture
  • Infection
  • Transient osteoporosis of the hip
  • Neurogenic pain
  • Sports hernia
  • Acetabular labral tear
  • Psoas bursitis
  • Synovitis or adhesions of the capsule
Treatment
General Measures
  • The diagnosis of osteonecrosis of the hip should be made as early as possible.
  • Other joints, including the contralateral hip, knees, shoulders, and ankles, should be evaluated.
  • Patients with this diagnosis should be
    evaluated by an orthopaedic surgeon who is experienced in treating
    osteonecrosis of the hip.
  • Nonoperative treatment typically is not successful for symptomatic lesions.
    • The failure rate is ~80%, depending on the size and classification of the lesion (4).
  • Small lesions have a higher rate of spontaneous resolution than do large lesions (9).

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Special Therapy
Physical Therapy
Physical therapy can be useful for maintaining ROM but usually is of little benefit.
Medication
First Line
  • Anticoagulants, antihypertensives, and
    lipid-lowering agents are all being investigated for the treatment of
    early-stage disease.
  • Currently, use of these pharmacologic agents should be considered experimental.
  • Evidence exists that diphosphonate may be helpful in preventing collapse (10).
Surgery
  • Surgery for the treatment of
    osteonecrosis of the hip can be divided into procedures that preserve
    the femoral head and arthroplasty options.
  • Head-preserving techniques:
    • Core decompression:
      • Indicated for small- to medium-sized precollapse lesions
      • Weightbearing should be protected for 5 weeks after surgery to avoid fracture.
      • Variable satisfactory outcomes have been reported (range, 40–90%) (5).
    • Osteotomy: Rotates the affected area of the head away from the weightbearing portion (11).
    • Vascularized fibular grafts: 1 study indicated an 83% success at 17-year follow-up in specialized centers (12).
    • Nonvascularized bone-graft:
      • Dead bone is removed and replaced with bone graft through a trapdoor in the femoral neck.
      • Reported success rate of 80–83% at 2.5–5 years follow-up (13)
  • Arthroplasty options:
    • Resurfacing arthroplasty:
      • Indicated for patients with severe femoral head collapse and minimal acetabular changes
      • Variable results have been reported (14).
    • Total hip arthroplasty:
      • Indicated for patients with femoral head collapse and acetabular involvement
      • A lower success rate is reported for patients with osteonecrosis than patients with osteoarthritis (4).
Follow-up
Prognosis
  • <50% of asymptomatic hips progress to end-stage disease requiring hip arthroplasty (5).
  • Nonoperative treatment of symptomatic lesions result in 79% failure rate (5).
  • Patients with diagnoses or risk factors
    thought to contribute to the development of osteonecrosis have worse
    outcomes with head-preserving procedures (5).
Complications
  • Progressive collapse of the hip can lead to debilitating arthritis and the need for total hip arthroplasties.
  • Risk of fracture exists with weightbearing after core decompression.
    • Risk is increased if the core tract is made through diaphyseal bone.
  • Risk of donor site morbidity exists with vascularized fibular grafting (15).
  • Hip arthroplasty in patients with
    osteonecrosis has a higher failure rate, owing to loosening, than in
    patients with osteoarthritis (20% versus 5%, respectively, at 10 years)
    (16).
    • With modern implants, bearing surfaces may become the limiting factor of replacements in younger patients (16).
Patient Monitoring
  • Serial radiographs are used to note any progression of joint involvement every 3–4 months.
  • Clinical symptoms are equally important,
    especially if nonoperative management is selected with the end point of
    total hip arthroplasty.
References
1. Ficat
RP, Arlet J. Functional investigation of bone under normal conditions.
In: Ischemia and Necrosis of Bone. Baltimore: Williams & Wilkins,
1980:29–52.
2. Steinberg ME, Hayken GD, Steinberg DR. A quantitative system for staging avascular necrosis. J Bone Joint Surg 1995;77B:34–41.
3. Hungerford DS, Lennox DW. Diagnosis and treatment of ischemic necrosis of the femoral head. In: Evarts CM, ed. Surgery in the Musculoskeletal System, 2nd ed. New York: Churchill Livingstone, 1990:2757–2794.
4. Mont MA, Jones LC, Hungerford DS. Nontraumatic osteonecrosis of the femoral head: ten years later. J Bone Joint Surg 2006;88A: 1117–1132.
5. Lieberman JR, Berry DJ, Mont MA, et al. Osteonecrosis of the hip: management in the 21st century. Instr Course Lect 2003;52: 337–355.
6. Pedersen
AB, Johnsen SP, Overgaard S, et al. Total hip arthroplasty in Denmark:
incidence of primary operations and revisions during 1996–2002 and
estimated future demands. Acta Orthop 2005;76:182–189.
7. Shpall EJ, Efremidis AP, Kasambalides E, et al. Case report 352: osteonecrosis of the femoral shaft (probably steroid-induced). Skeletal Radiol 1986;15:170–174.
8. Thickman D, Axel L, Kressel HY, et al. Magnetic resonance imaging of avascular necrosis of the femoral head. Skeletal Radiol 1986;15: 133–140.
9. Cheng EY, Thongtrangan I, Laorr A, et al. Spontaneous resolution of osteonecrosis of the femoral head. J Bone Joint Surg 2004;86A: 2594–2599.
10. Lai
KA, Shen WJ, Yang CY, et al. The use of alendronate to prevent early
collapse of the femoral head in patients with nontraumatic
osteonecrosis. A randomized clinical study. J Bone Joint Surg 2005;87A:2155–2159.
11. Shannon BD, Trousdale RT. Femoral osteotomies for avascular necrosis of the femoral head. Clin Orthop Relat Res 2004;418:34–40.
12. Urbaniak JR, Harvey EJ. Revascularization of the femoral head in osteonecrosis. J Am Acad Orthop Surg 1998;6:44–54.
13. Mont
MA, Einhorn TA, Sponseller PD, et al. The trapdoor procedure using
autogenous cortical and cancellous bone grafts for osteonecrosis of the
femoral head. J Bone Joint Surg 1998;80B: 56–62.
14. Adili A, Trousdale RT. Femoral head resurfacing for the treatment of osteonecrosis in the young patient. Clin Orthop Relat Res 2003;417: 93–101.
15. Vail TP, Urbaniak JR. Donor-site morbidity with use of vascularized autogenous fibular grafts. J Bone Joint Surg 1996;78A:204–211.
16. Hartley WT, McAuley JP, Culpepper WJ, et al. Osteonecrosis of the femoral head treated with cementless total hip arthroplasty. J Bone Joint Surg 2000;82A:1408–1413.
Miscellaneous
Codes
ICD9-CM
733.42 Osteonecrosis (aseptic necrosis), femoral head
Patient Teaching
Patients are counseled on the natural history of the
disease and are asked to call the physician’s attention to bone or
joint pain.
FAQ
Q: Will osteonecrosis of the hip get better?
A:
Spontaneous resolution occurs more often in patients with small
lesions. Larger lesions and those that have collapsed are unlikely to
improve spontaneously.
Q: Which patients should have total hip replacement?
Collapse of the femoral head and arthritic changes in the joint are indications for arthroplasty.

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