Avascular necrosis

1. Avascular Necrosis: Causes
and Treatment
Coleman D. Fowble, M.D.
Midlands Orthopaedics, P.A.
Columbia, SC

2. Introduction
• Definition
Loss of blood flow to the bone leading to death of
the cellular components of bone.

3. Avascular Necrosis
• AVN
• Osteonecrosis
• Aseptic necrosis
• Ischemic necrosis
• Bone infarction

4. Bones Affected
• Femoral head – most common by far
• Shoulder – humeral head
• Odontoid (Neck)
• Scaphoid (Wrist)
• Lunate (Wrist)
• Talus (Ankle)

5. Examples

6. Treatment
• Frustrating
• Staging very subjective in lower stages

7. Etiologies
• Trauma
• Alcohol
• Steroids
• Diving (Caisson’s Disease)
• Sickle Cell
• Idiopathic (up to 30% of cases)

8. Symptoms
• Pain
• Decreased range of motion

9. Risk Factors
• Alcoholism
• Pancreatitis
• Diabetes
• Gout

10. Staging
• Initially radiographic staging
• Revised with advancement of MRI

11. Classification
• Ficat
Original x-ray classification of hip
• Other classifications exist for talus, scaphoid,
etc.

12. Stage 0
• No clinical symptoms
• No radiographic abnormalities
• Microscopic diagnosis

13. Stage I
• May or may not have symptoms
• Radiographs and CT are normal
• MRI is abnormal as is bone scan
• Microscopic exam confirms diagnosis

14. Stage II
• Patient is symptomatic
• X-rays show osteopenia, sclerosis, cysts
• No subchondral lucency or collapse
• MRI confirms diagnosis

15. Stage III
• X-rays show subchondral lucency and collapse
Crescent sign
• Shape of femoral head is preserved
• Subclassified by extent of crescent
IIIa 15% of head
IIIb 15-30% of ahead
IIIc greater than 30%

16. Stage IV
• Flattening or collapse of head on x-ray
• Loss of joint space
• Subclassified by extent of collapse like Stage III
IVa
IVb
IVc

17. MRI Stage IV

18. Stage V
• Arthritic changes evident on x-rays with loss of
joint space and spurring
• May affect acetabular side of the joint

19. Stage V

20. Stage VI
• Extensive destruction of femoral head and
joint
• May be indistinguishable from osteoarthritis

21. Treatment Options
• Stage dependent
• Clinical signs and symptoms
• Physiologic condition
• Age
• Medical comorbidities

22. Observation
• Normal x-ray
• Possible abnormal MRI
• No clinical signs or symptoms

23. Core Decompression
• Stage I or II
• With or without hardware
• Age

24. Core Decompression
• Added fixation

25. Free Vascularized Fibular Graft
• Pioneered in 1979 by Dr. Urbaniak at Duke
• Over 2500 performed
• Multidisciplinary approach
• Only center with real consistent results

26. Core Decompression
• Vascularized fibular graft

27. Partial Resurfacing
• No Longer in favor
• Disastrous results
Loosening
Fracture
Migration of implant

28. Hip Replacement
• Too much destruction of head
• Age

29. Hip Resurfacing
• Age
• Bone preserving
• More functional hip replacement

30. Total Hip Versus Resurfacing

31. Workman's Compensation
• Trauma
• Secondary injury
• Difficult
May take several years to show up

32. Femoral Neck Fracture
• Basilar neck
• Transcervical
• Subcapital
• Intertrochanteric

33. Femoral Neck Fracture
• Location of fracture determines risk of AVN

34. Treatment Examples
• Fracture pattern determines treatment
• Other factors
Age
Comorbidities

35. Transcervical Fracture

36. Fixation
• 3 Screws
• Screw and sideplate
• Intramedullary device

37. AVN After Treatment
• AVN can occur long after treatment

38. Replacement
• Hemiarthroplasty
• Total hip

39. Summary
• AVN is the disruption of the blood supply to
bone
• There are multiple causes
• Diagnosis may be delayed
• Treatment is dependent on stage and other
factors

40. Sources
Staging of Avascular Necrosis. Orthopaedia Main. In:
Orthopaedia-Collaborative Orthopaedic Knowledgebase
JBJS Br. Core Decompression of the Distal Femur. Vol. 71-B.
August, 1989
JBJS. Treatment of Osteonecrosis with Free Vascularized Fibular
Graft. Vol 77. 1995