Avascular Necrosis: Causes and Treatment

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