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Primary Hip Arthroplasty Cemented & Uncemented
Frank R. Ebert, MD Union Memorial Hospital Baltimore, Maryland
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Johns Hopkins Union Memorial
Orthopædic Review Course
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Anatomic Approach Anterior Approach Anterior-Lateral Approach
Posterior Approach Medial Approach
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Anatomic Approach Open Reduction – CDH Pelvic Osteotomies
Intra-Articular Fusion Rarely Total Hip
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Internervous Plane Superficial
– Sartorius / TFL ( Femoral/Superior gluteal ) Deep – Rectus / gluteus medius ( Superior gluteal )
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Anterolateral Approach
Most common for THA ORIF of femoral neck Synovial biopsy of the hip
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Anterolateral Approach
Internervous plane – none TFL / gluteus medius Superior gluteal / Superior gluteal
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Lateral Approach Dangers – Superior gluteal nerve – Femoral nerve
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Medial Approach CDH open reduction Psoas Release Obturator Neurectomy
Biopsy or Treatment of tumors of femoral neck
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Medial Approach Internervous plane ( only deep ) Superficial :
Adductor Longus / gracilis Deep : Adductor Brevis / magnus
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Posterior Approach Internervous plane – none
splits gluteus maximus ( inferior gluteal )
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Primary Hip Arthroplasty
Posterior Approach Total hip replacement ORIF of posterior column fractures Dependent drainage of hip sepsis
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Primary Hip Arthroplasty
Posterior Approach Sciatic Nerve Inferior gluteal artery
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Primary Hip Arthroplasty
Design Features Size Shape Device configuration Material / physical properties
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Primary Hip Arthroplasty
Resist Composite Failure Prosthetic Device Bone Cement Cancellous Bone Cortical Bone
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Primary Hip Arthroplasty
Design Features Femoral Head Neck Stem Collar Acetabulum
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Primary Hip Arthroplasty
Prosthetic Hip Loading Changes from externally loaded system to an internally loaded system
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Primary Hip Arthroplasty
Femoral Head Design Articulating finish Head diameter
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DESIGN FEATURES Femoral Head
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Primary Hip Arthroplasty
32 mm Head Size Greater acetabular loosening Greatest volumetric wear Ritter COOR ‘76 Morrey JBJS ‘89
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Design Features 22mm Head Size
u Greatest linear wear u Greatest acetabular penetration Morrey JBJS 1989
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Design Features Charnley 22mm head diameter Compromise friction / wear
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Design Features 28 mm Head Size
Stable as 32mm head size Less torque than the 32mm head More favorable direct stress transmission patterns
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Primary Hip Arthroplasty
28 mm Head Size • Compromise
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Primary Hip Arthroplasty
Design Features Femoral Neck Geometry Neck stem angle – 135º Neck stem offset – large offset Bending moment – small offset Decreases moment arm
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Primary Hip Arthroplasty
Design Features Femoral Stem – Length – Shape – Material properties – Surface finish
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Primary Hip Arthroplasty
Femoral Stem Design Cross sectional geometry Defines strength / stiffness Avoid sharp corners
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Primary Hip Arthroplasty
Femoral Stem Design Large lateral volume Less tensile stress in the mantle laterally Large medial volume less tensile stress
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Primary Hip Arthroplasty
Collar Primary role for optimal load transfer to proximal femur Crowninshield JBJS ‘80 Andriacchi JBJS ‘76
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Primary Hip Arthroplasty
Collar Reduces adaptive bone resorption Reduce bending stress in the component Reduce stress in the distal cement
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Primary Hip Arthroplasty
Fixation Features PMMA Weak link Poor fracture toughness Low tensile and fatigue strength Elastic modulus 1/3 lower than cortical bone
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Primary Hip Arthroplasty
Fixation Features PMMA Improvements Carbon Fibers Decreased cement intrusion / increased viscosity Low Viscosity Lower fatigue strength Centrifugation Improved tensile and fatigue strength
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PMMA Improvements Centrifugation 30 sec / 4000 rpm Vacuum
Burke JBJS ‘84 Chin/Stauffer JBJS ‘90
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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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Primary Hip Arthroplasty
Acetabulum Design Metal backed All polyethylene
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Primary Hip Arthroplasty Cement Fixation :
The Femoral Side Results directly related to Surgical Techniques
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Primary Hip Arthroplasty
Metal Backed Increased linear and volumetric wear Increased radiolucency, loosening, revision No series of documented superior results
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Improved Longevity – Femoral Side
Plug canal Retrograde fill Avoid varus / valgus > 5º Mulroy JBJS ‘95
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Primary Hip Arthroplasty
Grade Radiographic Appearance A White-Out B Complete Distribution C1 Extensive Radiolucent Line C2 Thin mantle < 1 mm D Gross deficiencies
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Primary Total Hip 1st Generation Cement Technique
– Finger Packing – No pressurization – No Canal Prep – Cast stem – No Plug – Narrow med border – No Gun – Sharp edges WH Harris
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Primary Hip Arthroplasty Cement Techniques
Probable Improved Longevity Femoral Side Pressurize Centralize Continuous Cement Mantle Harris COOR ‘97
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Cemented Long Term
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Primary Total Hip 2nd Generation Cement
William Harris Began 1975 Gun 71 – Super alloy Jet lavage – Broad & round medial border Canal Prep Cement Restriction
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Primary Total Hip Cemented Long Term
Results 25 year Survivorship Acetabulum Survive Age < % % % Femur < % % % Barry et al 1998
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Primary Total Hip 25 Year Follow-Up
Total Aseptic Loosening Acetabulum % Revision Radiologic 19.4 Total: Femoral % Revision Radiologic 8.1 Callaghan, Johnston, JBJS ‘97. Harris Course ‘98
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Cemented Primary Total Hip Clinical Results with 2° Generation Techniques
Follow Up Revision Rate Hips Neumann (94) yrs 8.3% Schulte yrs 3% Wroblewski yrs 6% Kavanagh yrs 16%
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Cemented Primary Total Hip Clinical Results with 2º Generation Techniques
Follow Up Revision Rate Hips Barrack yrs 0% Madey yrs 1% Mulroy yrs 2% Smith yrs 5%
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Primary Total Hip Clinical Results
Cemented Total Hip: 2nd Generation 14-17 year follow-up – 102 hips Femoral loosening 2% revised Acetabular loosening 10% revised 42% radiologic Mulroy, Harris, JBJS ‘95; COOR ‘97
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Cemented Primary Total Hip Clinical Results — Acetabular Side
Rev. Rate Loosen-ing Prosthesis Hips Sullivan 94 Charnley 89 13% 37% Smith 98 CAD 65 23% 26% Callaghan 98 Charnley 93 19% 15%
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Primary Total Hip 3rd Generation Cement Technique
Bill Harris – Began 1982 Porosity reduction Rough surface Centralization Pressurization Pre-coat
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Primary Total Hip Conclusions — Cemented Plug and retrograde fill
Avoid excessive varus/valgus Strive for 3-5 mm prox/med > 2mm distal Do not ream / remove good cancellous bone
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Primary Total Hip Clinical Results
Hybrid Construct Galante f/u 5 years Femoral 2% rad loose Acetabulum 2% rad loose Woolson - 96 f/u 6 years Femoral 5% revision Acetabulum 0% revision
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Design Features POROUS IMPLANT
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Uncemented THA Definition Press Fit Macrointerlock Microinterlock
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Design Features Pore Size — Animal Studies
50 to 400 µm Optimal bone ingrowth Bobyn: Clinical Orthopedics; 1980 Engh: JBJS; 1987 Collier: Clinical Orthopedics; 1988
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Micromotion 40 Micron Motion Bone Ingrowth (JBJS 79-A)
150 Micron Motion Fibrous Ingrowth (CORR, 208)
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Design Criteria – Long Term Implant Stability
Initial Implant Stability Implant micromotion < 50 mm of displacement Level of implant coating Type of coating Kienapfel H. J. Arthroplasty 1999
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Design Criteria Uncemented Total Hip Arthroplasty
Key — Resistance to Rotation Around the Long Axis
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Design Criteria Uncemented Total Hip Arthroplasty
Resist translation in 3 planes Axial Medial - lateral Anterior - posterior
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Design Criteria – Uncemented Implants
Level of Implant Coating Apply circumferential Avoid patch porous coats Smooth surface – high failure rate
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Design Criteria – Uncemented Implants
Type of Coating 1. Macro-texturing — doesn’t work 2. Roughened titanium 3. Porous coating made of CoCr or Ti 4. Ti wire mesh 5. Plasma-sprayed Ti 6. Bioactives — Hydroxyapatite / tricalcium phosphate
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Design Features Sintered Micro/Macro Beads Cr-Co-Mo/Ti
Pore dimensions 100 to 400 mm AML ; PCA
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Sintered with controlled coating 30 200
Fatigue strength Process psi MPa Forged Cast Sintered Sintered with controlled coating *Data from Pilliar, R.M. Clin. Orthop. 176:42-51, 1983.
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Design Criteria – Uncemented Implants
Implant Geometry – Implant Stability 1) Wedge-shaped metaphyseal filling 2) Single wedge-shaped implants 3) Tapered stems 4) Diaphyseal fixation — cylindrical or fluted stems
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Design Criteria Uncemented Implants Requires cortical fixation
Metaphysis Metaphysis – Diaphysis Diaphyseal
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Design Criteria – Uncemented Implants
Bioactives — Osteoconductive Tricalcium dissolves more rapidly than hydroxyapatite Thickness 50 mm More crystalline hydroxyapatite slows resorption
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Uncemented Primary Total Hip Clinical Results • Femoral Side
— Titanium = Cobalt Chrome — Cobalt Chrome increased stress- shielding — Straight Stems with varying degrees of medullary fill often used — Anatomic Stems have not been a great advantage
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Design Features u Straight Stem uAn Anatomic Stem
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Design Features Proximal Coating
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Design Features u Proximal coating – Anatomic design
u Maximum fit in certain priority areas u Maximal load transfer u Resist axial loading and torsional loads Poss: Clinic
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Design Features Compared with proximal motion
u Both greater distal motion at interface — Compared with proximal motion Callaghan, JBJS ‘92
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The HGP stem (courtesy of Zimmer)
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Design Features Porous Implant Fully coated u Proximal coating u
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Design Features — Porous Surface
u 2/3 or fully coated 2 to 4 x increase in bone resorption Engh: Clinical Orthopedics; 1988
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Engh: Clinical Orthopedics; 1988
Design Features Fully Coated Porous Surface u Transfers stress distally under axial load – Proximal bone resorption Engh: Clinical Orthopedics; 1988
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Retrieval Studies Engh Femur 57% ingrowth Acetabulum 32% ingrowth
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Radiographic Criteria for Bone Ingrowth
Engh et al, (CORR 257) Absence of Reactive Lines Spot Welds Endosteal Bone Implant Instability 2 mm Pedestal Calcar Atrophy / Stress Shielding
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Uncemented Primary Total Hip Clinical Results • Femoral Side
Straight Stem Design % loosening AML 507 hips yrs 1.2% Harris/ Galante 121 hips yrs 3.3% Omniflex 88 hips yrs 3.4% Taperloc 145 hips yrs 0.7% Trilock 71 hips > 10 yrs 0%
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Uncemented Primary Total Hip Clinical Results • Femoral Side
% Anatomic Stem Design loosening APR hips yrs 11% APR hips 2-5 yrs 0% PCA 539 hips 6-8 yrs 7.6% 100 hips > 7 yrs 2.0%
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Screw Fixation Less Micromotion, Better Ingrowth
Conduit for Particulate Debris Neurovascular Injury
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Acetabular Design Hemisphere Screw Fixation Locking Mechanism
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Uncemented Primary Total Hip — Main Recurrent Concern
Poly Wear – Osteolysis
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Uncemented Primary Total Hip Clinical Results • Acetabular Side
Femoral head size – Acetabular thickness PCA 26 mm head no osteolysis PCA 32 mm head % osteolysis
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Uncemented Primary Total Hip Clinical Results • Acetabular Side
% loosening ARC 72 hips 12 yrs 1.4% Harris/Galante 136 hips 5-10 yrs 0% PSL smooth HA 316 hips 6-10 yrs 12% beaded HA % PCA 241 hips 2-9 yrs 11% hips 7 yrs 13.2% > 7 yrs 4% rev.
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Uncemented Primary Total Hip Clinical Results • Acetabular Side
— Hemispherical shape — rim fit — Under ream No > 2 mm — Screws : produced durable results - postop Disadvantage : posterior sciatic N. Ant sup – common iliac Ant inf – obturator art / ner {
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Complications in Total Hip Arthroplasty – Heterotopic Ossification
Treatment Radiation pre-op or post-op 500 to 1000 Rad “Remember to shield implant” Indomethacin Ibuprofen Diphosphonates
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Associated conditions Ankylosing spondylitis Forestier’s disease
Complications In Total Hip Arthroplasty – Heterotopic Ossification 0.6% to 61.7% Associated conditions Ankylosing spondylitis Forestier’s disease Post traumatic arthritis Bilateral male osteophytic OA
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Complications in Total Hip Arthroplasty – Dislocation
Component Impingement Proximal femur Femoral head skirt Acetabular component (elevated liner) Osteophytes / cement masses Head Size No difference 28 mm head > 60 mm acetabulum —increased rate 22 mm head > 54 mm acetabulum —increased rate
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Complications In Total Hip Arthroplasty – Dislocation – 3%
Posterior approach slightly higher 4.6% Neuromuscular problems Previous surgery (rate doubles) Malposition > 25º anteversion > 60º inclination Retroversion > 15º femoral anteversion
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Treatment Bracing Spica cast Surgery
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Complications In Total Hip Arthroplasty – Dislocation
Occult infection Trauma Profound weight loss
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Complications In Total Hip Arthroplasty – Thromboembolism
Most common complication DVT – 70% to 8% PE – 1% to 2%
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Complications In Total Hip Arthroplasty – Thromboembolism
Activation of clotting cascade Local vessel injury Stasis in the femoral vein
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1. Elastic 2. Viscoelatic-plastic 3. Rigid 4. Shear thinning
Ultra-High Molecular Weight Polyethylene is defined as what type of material ? 1. Elastic 2. Viscoelatic-plastic 3. Rigid 4. Shear thinning 5. High friction
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1. Increased ionic bonding 2. Surface ion implantation
The degradation of polyethylene following gamma irradiation is related to what factor ? 1. Increased ionic bonding 2. Surface ion implantation 3. Free radical formation 4. Decreased covalent cross- linking 5. Decreased polymer density
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1. Less particulate metal debris 2. Less stiffness
Why is cobalt-chrome alloy preferred over a titanium alloy for a cemented femoral component in a total hip arthroplasty ? 1. Less particulate metal debris 2. Less stiffness 3. Elastic modulus closer to bone cement 4. Cost-effectiveness 5. Better cement bonding ability
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3. Periprosthetic femur fracture 4. Acetabular component loosening
What is the most common long-term complication of cemented total hip arthroplasty in patients under 50 years of age? 1. Age 2. Dislocation 3. Periprosthetic femur fracture 4. Acetabular component loosening 5. Femoral stem fracture
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The bleeding is most likely from which artery? 1. Superior gluteal.
During a posterior approach to the hip joint, profuse bleeding is encountered during incision of the quadratus femoris. The bleeding is most likely from which artery? 1. Superior gluteal. 2. Inferior gluteal. 3. Lateral femoral circumflex. 4. Medial femoral circumflex. 5. Posterior femoral circumflex.
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Which is the correct order of the elastic modulus of the following materials, from the lowest to highest modulus? 1. Polyethylene, cancellous bone, cortical bone, titanium alloy, cobalt chrome alloy 2. Cancellous bone, cortical bone, polyethylene, titanium alloy, cobalt chrome alloy 3. Cancellous bone, cortical bone, polyethylene, cobalt chrome alloy, titanium alloy 4. Cancellous bone, polyethylene, cortical bone, cobalt chrome alloy, titanium alloy 5. Cancellous bone, polyethylene, cortical bone, titanium alloy, cobalt chrome alloy
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Thank You
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