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Primary Hip Arthroplasty Cemented & Uncemented

Primary Hip Arthroplasty Cemented & Uncemented. Frank R. Ebert, MD. Union Memorial Hospital Baltimore, Maryland. Johns Hopkins Union Memorial. Orthopædic Review Course. Anatomic Approach. Anterior Approach Anterior-Lateral Approach Posterior Approach Medial Approach. Anatomic Approach.

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Primary Hip Arthroplasty Cemented & Uncemented

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  1. Primary Hip ArthroplastyCemented&Uncemented Frank R. Ebert, MD Union Memorial HospitalBaltimore, Maryland

  2. Johns HopkinsUnion Memorial Orthopædic Review Course

  3. Anatomic Approach • Anterior Approach • Anterior-Lateral Approach • Posterior Approach • Medial Approach

  4. Anatomic Approach • Open Reduction – CDH • Pelvic Osteotomies • Intra-Articular Fusion • Rarely Total Hip

  5. Internervous Plane • Superficial • – Sartorius / TFL ( Femoral/Superior gluteal ) • Deep • – Rectus / gluteus medius ( Superior gluteal )

  6. Anterolateral Approach • Most common for THA • ORIF of femoral neck • Synovial biopsy of the hip

  7. Anterolateral Approach • Internervous plane – none • TFL / gluteus medius • Superior gluteal / Superior gluteal

  8. Lateral Approach • Dangers • – Superior gluteal nerve • – Femoral nerve

  9. Medial Approach • CDH open reduction • Psoas Release • Obturator Neurectomy • Biopsy or Treatment of tumors of femoral neck

  10. Medial Approach • Internervous plane ( only deep ) • Superficial : • Adductor Longus / gracilis • Deep : • Adductor Brevis / magnus

  11. Posterior Approach • Internervous plane – none • splits gluteus maximus ( inferior gluteal )

  12. Primary Hip Arthroplasty • Posterior Approach • Total hip replacement • ORIF of posterior column fractures • Dependent drainage of hip sepsis

  13. Primary Hip Arthroplasty • Posterior Approach • Sciatic Nerve • Inferior gluteal artery

  14. Primary Hip Arthroplasty • Design Features • Size • Shape • Device configuration • Material / physical properties

  15. Primary Hip Arthroplasty • Resist Composite Failure • Prosthetic Device • Bone Cement • Cancellous Bone • Cortical Bone

  16. Primary Hip Arthroplasty • Design Features • Femoral Head • Neck • Stem • Collar • Acetabulum

  17. Primary Hip Arthroplasty • Prosthetic Hip Loading • Changes from externally loaded system to an internally loaded system

  18. Primary Hip Arthroplasty • Femoral Head Design • Articulating finish • Head diameter

  19. DESIGNFEATURES Femoral Head

  20. Primary Hip Arthroplasty • 32 mm Head Size • Greater acetabular loosening • Greatest volumetric wear Ritter COOR ‘76Morrey JBJS ‘89

  21. Design Features22mm Head Size • u Greatest linear wear • uGreatest acetabular penetration MorreyJBJS 1989

  22. Design Features • Charnley 22mm head diameter • Compromise friction / wear

  23. Design Features28 mm Head Size • Stable as 32mm head size • Less torque than the 32mm head • More favorable direct stress transmission patterns

  24. Primary Hip Arthroplasty • 28 mm Head Size • • Compromise

  25. Primary Hip Arthroplasty • Design Features Femoral Neck Geometry • Neck stem angle – 135º • Neck stem offset • – large offset . . . Bending moment • – small offset . . . Decreases moment arm

  26. Primary Hip Arthroplasty • Design Features • Femoral Stem • – Length • – Shape • – Material properties • – Surface finish

  27. Primary Hip Arthroplasty • Femoral Stem Design • Cross sectional geometry • Defines strength / stiffness • Avoid sharp corners

  28. Primary Hip Arthroplasty • Femoral Stem Design • Large lateral volume • Less tensile stress in the mantle laterally • Large medial volume less tensile stress

  29. Primary Hip Arthroplasty • Collar • Primary role for optimal load transfer to proximal femur Crowninshield JBJS ‘80Andriacchi JBJS ‘76

  30. Primary Hip Arthroplasty • Collar • Reduces adaptive bone resorption • Reduce bending stress in the component • Reduce stress in the distal cement

  31. Primary Hip Arthroplasty • Fixation Features • PMMA • Weak link • Poor fracture toughness • Low tensile and fatigue strength • Elastic modulus 1/3 lower than cortical bone

  32. Primary Hip Arthroplasty • Fixation FeaturesPMMA Improvements • Carbon Fibers Decreased cement intrusion / increased viscosity • Low Viscosity Lower fatigue strength • Centrifugation Improved tensile and fatigue strength

  33. PMMA Improvements • Centrifugation 30 sec / 4000 rpm • Vacuum Burke JBJS ‘84Chin/Stauffer JBJS ‘90

  34. Primary Hip Arthroplasty • Material Properties • Stainless Steel — high elastic modulus / low fatigue strength • Cobalt Chrome — highest elastic modulus / better yield / fatigue strength • Titanium — lower elastic modulus / less stiffness

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