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Avascular Necrosis: Causesand Treatment
Coleman D. Fowble, M.D.
Midlands Orthopaedics, P.A.
Columbia, SC
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Introduction
Definition
Loss of blood flow to the bone leading to death of
the cellular components of bone.
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Avascular Necrosis
AVN
Osteonecrosis
Aseptic necrosis Ischemic necrosis
Bone infarction
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Bones Affected
Femoral head most common by far
Shoulder humeral head
Odontoid (Neck) Scaphoid (Wrist)
Lunate (Wrist)
Talus (Ankle)
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Examples
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Treatment
Frustrating
Staging very subjective in lower stages
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Etiologies
Trauma
Alcohol
Steroids Diving (Caissons Disease)
Sickle Cell
Idiopathic (up to 30% of cases)
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Symptoms
Pain
Decreased range of motion
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Risk Factors
Alcoholism
Pancreatitis
Diabetes Gout
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Staging
Initially radiographic staging
Revised with advancement of MRI
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Classification
Ficat
Original x-ray classification of hip
Other classifications exist for talus, scaphoid,
etc.
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Stage 0
No clinical symptoms
No radiographic abnormalities
Microscopic diagnosis
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Stage I
May or may not have symptoms
Radiographs and CT are normal
MRI is abnormal as is bone scan Microscopic exam confirms diagnosis
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Stage II
Patient is symptomatic
X-rays show osteopenia, sclerosis, cysts
No subchondral lucency or collapse MRI confirms diagnosis
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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%
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Stage IV
Flattening or collapse of head on x-ray
Loss of joint space
Subclassified by extent of collapse like Stage IIIIVa
IVb
IVc
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MRI Stage IV
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Stage V
Arthritic changes evident on x-rays with loss of
joint space and spurring
May affect acetabular side of the joint
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Stage V
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Stage VI
Extensive destruction of femoral head and
joint
May be indistinguishable from osteoarthritis
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Treatment Options
Stage dependent
Clinical signs and symptoms
Physiologic condition Age
Medical comorbidities
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Observation
Normal x-ray
Possible abnormal MRI
No clinical signs or symptoms
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Core Decompression
Stage I or II
With or without hardware
Age
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Core Decompression
Added fixation
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Free Vascularized Fibular Graft
Pioneered in 1979 by Dr. Urbaniak at Duke
Over 2500 performed
Multidisciplinary approach Only center with real consistent results
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Core Decompression
Vascularized fibular graft
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Partial Resurfacing
No Longer in favor
Disastrous results
Loosening
Fracture
Migration of implant
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Hip Replacement
Too much destruction of head
Age
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Hip Resurfacing
Age
Bone preserving
More functional hip replacement
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Total Hip Versus Resurfacing
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Workman's Compensation
Trauma
Secondary injury
DifficultMay take several years to show up
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Femoral Neck Fracture
Basilar neck
Transcervical
Subcapital
Intertrochanteric
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Femoral Neck Fracture
Location of fracture determines risk of AVN
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Treatment Examples
Fracture pattern determines treatment
Other factors
Age
Comorbidities
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Transcervical Fracture
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Fixation
3 Screws
Screw and sideplate
Intramedullary device
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AVN After Treatment
AVN can occur long after treatment
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Replacement
Hemiarthroplasty
Total hip
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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
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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
