Avascular necrosis, also known as osteonecrosis or bone infarction, is the death of bone tissue due to a lack of blood supply. It most commonly affects the femoral head. There are many potential causes including trauma, alcohol use, steroid use, and idiopathic cases. Diagnosis is made through imaging like x-rays, CT scans, MRIs, and bone scans. Treatment depends on the stage of necrosis and other factors, and may include observation, core decompression, vascularized bone grafts, partial or total hip replacement, or hip resurfacing. Staging is important for determining treatment and can range from pre-symptomatic changes visible only on MRI to complete femoral head destruction indistinguishable from osteo

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