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

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

Avascular Necrosis AVN Osteonecrosis Aseptic necrosis Ischemic necrosis Bone infarction

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

Examples

Treatment Frustrating Staging very subjective in lower stages

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

Symptoms Pain Decreased range of motion

Risk Factors Alcoholism Pancreatitis Diabetes Gout

Staging Initially radiographic staging Revised with advancement of MRI

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

Stage 0 No clinical symptoms No radiographic abnormalities Microscopic diagnosis

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

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

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%

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

MRI Stage IV

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

Stage V

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

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

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

Core Decompression Stage I or II With or without hardware Age

Core Decompression Added fixation

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

Core Decompression Vascularized fibular graft

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

Hip Replacement Too much destruction of head Age

Hip Resurfacing Age Bone preserving More functional hip replacement

Total Hip Versus Resurfacing

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

Femoral Neck Fracture Basilar neck Transcervical Subcapital Intertrochanteric

Femoral Neck Fracture Location of fracture determines risk of AVN

Treatment Examples Fracture pattern determines treatment Other factors Age Comorbidities

Transcervical Fracture

Fixation 3 Screws Screw and sideplate Intramedullary device

AVN After Treatment AVN can occur long after treatment

Replacement Hemiarthroplasty Total hip

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

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