Avascular Necrosis Causes and Treatment Coleman D Fowble

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 77. 1995