AVN of the Femoral Head

1
AVN of the Femoral Head

• Jeff Easom, D.O.
• Garden City Hospital

2
Introduction

• Debilitating disease that usually leads to hip
  joint destruction
• 30 to 50 year old age group (avg. 33)
• Ten to twenty thousand new patients annually
• 5 to 12 of THA annually secondary to AVN
• BL in 50 to 80 of pts

3
Etiology

• Healthy cancellous bone replaced by dead
  trabecular bone.
• Bone and marrow death can result from vascular
  interruption by various means and may extend to
  subchondral plate
• Anterolateral femur predominantly affected

4

• Presumed mechanism of mechanical failure due to
  accumulated stress fractures of unrepaired
  necrotic trabeculae
• Crescent sign - Earliest sign of mechanical
  failure
• No collateral vasculature in areas of subchondral
  bone

5
Clinical Conditions Assoc. with AVN

• Corticosteroids(SLE, RA, renal transplant,
  asthma)
• ETOH, Sickle Cell, Gaucher, coagulation
  deficiencies, myeloproliferative disorders,
  trauma, Caisson disease, radiation

6

• ETOH and corticosteroids account for approx 90
  of AVN (non-traumatic)-Mont et al, JBJS, Vol 77A,
  No. 3, March 1995
• Increased risk in individuals who drink as little
  as 400ml/week (JBJS, Vol 77A, No. 3, March 1995

7
Pathogenesis

• Multiple theories
• Thromboemboli, nitrogen bubbles, abnormally
  shaped RBCs, bone marrow pressure, radiation
  damage, altered lipid metabolism, vasoactive
  factor release as Gaucher disease
• AVN is multifactorial in origin with a final
  common pathway

8
Pathology

• Subchondral infarcted bonegtinneffective healing
  responsegtresorption of dead bonegtreplacement with
  fibrous and granulation tissuegtthick trabeculae
  formationgtcartilage collapse

9
Clinical Features

• Severe pain over anterior hip and groin (deep or
  throbbing pain)
• Pain worsened with WB and motion (esp. forced
  internal rotation)
• Acute or insiduous onset
• Night pain
• Positive Trendelenburg sign

10
Diagnosis

• AP/frog-leg lateral radiographs
• Bone scan/bone bx- not standard diagnostic test
• MRI - aids in determining extent. Earliest
  finding is a single density line on T1-weighted
  images, double-line sign on T2-weighted images

11

• Diagnosis does not depend on a single finding,
  but based on the entire clinical picture, hx, and
  PE.
• HIGH index of suspicion

12
Staging

• Ficat and Arlet - Based on standard radiographs
• Steinberg - Expanded Ficat and Arlet to include
  extent of femoral head involvement
• Marcus
• Japanese Investigation Committee - Modified Ficat
  and Arlet to include location of lesion

13
Ficat and Arlet
14
Steinberg

• Mild - lt15 of femoral head involved
• Moderate 15 to 30
• Severe - gt30

15
Marcus
16

• ARCO(Association Research Circulation Osseous) -
  proposed new classification to include prior 3
  classification systems. Not universally accepted
  or finalized yet.(JBJS,Vol 77-A, No. 3, March
  1995)
• Expanded Ficat and Arlet to incorporate concept
  of location of lesion on radiograph.
• Type-A-medial, Type-B-central, and Type C-lateral

17
Stage II
18
Stage III
19
(No Transcript)
20

• Crescent sign Early collapse of femoral head

21
Stage IV
22
MRI
23
Natural History

• Remains uncertain
• Studies have shown that gt 85 rate of collapse
  within 2 years when stages I and II symptomatic
  hips were left untreated
• Overall, when the diagnosis is made, the
  condition will progress

24
Non-Operative Treatment

• Observation
• Protected Weight-Bearing
• 21 studies/819 hips - 182(22) with satisfactory
  clinical result with avg. f/u of 34 months. (Mont
  et al JBJS, Vol 77-A, No. 3, March 1995
• Pharmacological Tx - Limited use and studies
  uncontrolled

25

• Preliminary investigation of vasoactive and
  lipid-lowering agents are ongoing at several
  centers
• Electrical stimulation - Remains experimental.
  Mixed outcomes with published articles

26
Operative Treatment

• Core Decompression (with/without electrical
  stimulation). Stages I and II
• Osteotomy(Varus, Flexion, Rotational). Stages III
  and IV
• Non-Vascularized Bone-Grafting
• Vascularized Grafts
• Bipolar hemiarthroplasty, TARA, THA

27
Core Decompression

• Stage I and II - no subchondral fracture or
  collapse

28
Mont et al, CORR, No. 324, March 1996

• 42 studies/2025 hips tx with core
  decompression(1206 hips) and non-operative
  management(819). Satisfactory results (63.5/24
  studies) of core decompression. 63 showed no
  evidence of radiograph disease prog.
• 22.7 success/21 studies of non-operative group

29

• 84 femoral head survival with Stage I, 65 with
  Stage II, and 47 with Stage III in the core
  decompression group
• 35 hip survival rates for Stage I, 31 for Stage
  II, and 13 for Stage III in non-operative
  treatment group

30
Stulberg et al, CORR, No. 268, July 1991

• Prospective study over 4 year period
• 55 hips/36 patients
• 29 core decompression/26 non-operative
• Avg. age 38
• Avg. f/u 27 months

31
Result

• Success based on HHS. Stage I - 70 (7/10
  operative hips) and 20(1/5) in non-operative
  hips. Stage II - 71 (5/7) and 0/7 of
  non-operative. Stage III - 73 (8/11) operative
  and 1/10 non-operative
• Results of success based on HHS and not on
  radiographic criteria

32
Core and Bone Grafting - Vascularized Fibular
Graft

• Attempts to enhance revascularization and arrest
  progression of necrosis
• 60 to 90 success rate
• Stage II, III, IV, V - Urbaniak

33
Urbaniak et al, JBJS, Vol 77-A, No. 5, May 1995

• Free vascularized fibular grafting in symptomatic
  AVN - prospective
• 103 hips/89 pts followed (median f/u 7 years
• Followed yearly with regard to HHS, radiographic
  progression, and conversion to THA

34
Results

• Probability of conversion to THA within 5 years
  was 11(Stage II), 23(Stage III), 43 (Stage
  IV), 32 (Stage V)
• HHS - Improvement from 56 to 80 (Stage II), 52 to
  85 (Stage III), 41 to 76 (stage IV), and 36 to 75
  (Stage V).
• Radiographic progression occurred in 7/19 stage
  II, 21/22 stage III, 31/40 stage IV, and 16/22
  stage V

35
Osteotomy

• Predicated on concept of realignment with relief
  of lesion from weightbearing zone (delivered from
  weight bearing or contained within acetabulum)
• Varus, flexion, valgus-flexion, and rotational
  osteotomies
• With lesions of a total of 200 degrees, osteotomy
  is not recommended

36

• All usually require an extended period of limited
  weight bearing of up to a year
• Sugioka et al - Transtrochanteric rotational
  osteotomy. Technically demanding and results have
  not been duplicated
• Various osteotomies exist with outcomes being
  widely varied

37

• Difficulty with osteotomy is the increased
  difficulty in obtaining a satisfactory result if
  a THA is necessary
• 93/105 THAs after osteotomy had intraoperative
  difficulties(screw removal and femoral reaming)
• Ideal candidate is stage III with a small lesion
  and no ongoing cause of AVN

38
Additional Treatment Alternatives

• Bipolar hemiarthroplasty - not recommended now
• TARA - Older design prosthesis yielded poor
  results, while newer prosthetic design may yield
  better outcomes
• Arthrodesis- Not widely advocated

39
Hungerford et al, JBJS, Vol 80-A, No. 11,
November 1998

• 33 hips/25 pts
• Ficat Stage III and early Stage IV-( collapse
  without involvement of acetabulum)
• TARA (Depuy)
• Mean f/u 10.5 years
• Mean age 41 y.o.
• Femoral head resurfacing only

40
Results

• 30 hips/91 survived at least 5 years
• Mean f/u 10.5 yrs Overall, 20 hips(61) had
  good or excellent results based on HHS13(39)
  had fair or poor result and required THA
• Mean interval b/w TARA and THA 60 months

41

• HHS Mean improvement from 38 points (range of
  29 to 61 points) preoperatively to 91
  points(range of 80 to 100.

42
Conclusion

• After determination of whether or not collapse
  has occurred, one must consider the extent of the
  lesion, which has been found to be important
  prognostically(lesions involving lt 15 of femoral
  head fare better with all treatment method than
  moderate or severe lesions

43

• Medial (type-A) lesions have been found to have a
  much better prognosis than central (type-B), or
  lateral (type-C).
• Overall, patients with multisystem disease or
  post transplantation state should have THA as a
  definitive procedure rather than preservation
  procedures

44

• Conservative tx 20 survival rate at 3 to 5
  years for Stage I and II AVN
• Core decompression 70 to 80 survival rate in
  Stage I and II AVN at 3 to 5 years
• Vascularized fibular grafting Clinical success
  approx 70 80 in Stage III, IV, and V AVN

45

• Osteotomy 50 to 70 success rate at 5 years in
  Stage III AVN
• THA Higher rate of failure than for OA, but
  clinically better than alternatives for advanced
  disease
• TARA Best study represents 61 clinical success
  at 10.5 years