REVIEW OF CEMENTLESS TOTAL HIP ARTHROPLASTY: 5yr results utilizing a horizontal platform stabilized design

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REVIEW OF CEMENTLESS TOTAL HIP ARTHROPLASTY 5yr
results utilizing a horizontal platform
stabilized design
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THA Historical

• Cemented THA provided marked improvement in fcn
  for millions of patients
• 1970s failure due to loosening of cemented
  components was first noted
• This was felt to be one of the most important
  long term complications of the procedure

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THA Historical

• Due to problems with loosening of devices
  inserted with cement
• An alternative method of fixation in which a
  device could be directly anchored to bone
• ? led surgeons in the U.S. and Europe to
  further investigate porous coated implants in THA

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THA Historical

• 1910 GREENFIELD dev. Concept of biologic
  fixation by obtaining a patent for a metallic
  cage-like framework for the root of an artificial
  tooth.
• 50yrs dedicated to filling soft tissue def.
• 1963 SMITH first to use porous materials for
  ingrowth (ceramic-plastic composite,pore size
  1-25 micrometers)

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THA Historical

• 1969 HIRSCHHORN REYNOLDS porous coated
  chromium alloy with powder metallurgy technique
• 1969 LUECK titanium-fiber composite fabricated
  and implanted
• 1970s to present stem development has advanced
  signif. considers types of coating, pore
  size,available metals, inhibitors of bone
  ingrowth designs of implants.

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REVIEW THA cementless

• BROAD CATEGORY OF DESIGN TYPES
• VARIETY OF BONE TYPES DORR CLASS
• RESTRICT USE BASED ON
• 1. Pt. age
• 2. Configuration of medullary canal
• 3. Specific Bone disease

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DORR CLASSIFICATION
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REVIEW THA cementless

• IN GENERAL
• CEMENLESS STEMS gt
• 1. YOUNGER 75YRS
• 2. FUNNEL SHAPED PROXIMAL
• FEMURS
• 3. ETIOLOGIES AVN, OA, POST-
• TRAUMATIC

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REVIEW THA cementless

• IN GENERAL gt
• CEMENTED STEMS
• 1. OLDER 75YRS
• 2. CYLINDRICAL MORPHOLOGY OF
• PROXIMAL FEMURS
• 3. ETIOLOGIES INFLAMMATORY,
• METABOLIC BONE DISEASE

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Lewallen et al.. 1999 CORRSudden Death During
Primary Hip Arthroplasty

• 38,488 hips in 29,431 patients
• 1969-1997 23 intra-operative deaths
• 11 cemented THA, 12 cemented Hemi.
• Mean age 80.9
• All deaths irrev. Cardiorespiratory disturbances
• Concluded elderly pts with pre-existing
  cardiovasc. Conditions undergoing cemented
  arthroplasty are at increased risk for
  intraoperative death.

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LaPorte, Mont, Hungerford Review proximally
porous coated Ingrowth Prostheses limits of Use.
Orthopedics 1999
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REVIEW THA cementless

• THIGH PAIN
• gt RORABECK REPORTED 6 INCIDENCE
  USING
• THE SYNERGY HIP
• gt RANGE IN THE LITERATURE FROM
  6-30
• gt RELATED DIRECTLY TO STEM
• CHARACTERISTICS AND BONE
  MORPHOLOGY
• gt THE DEGREE OF POROUS COATING
  AND STEM
• STIFFNESS DIRECTLY
  CORRELATE WITH BONE
• DENSITY AND ARCHITECHTURE

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REVIEW THA cementless

• THIGH PAIN
• -PRESS FIT STEMS HAVE BEEN
• USED IN DORR TYPE C CYLINDRICAL
  FEMURS
• gt IMPLANTS HAVE TO BE LARGE IN
  DIAMETER
• gt CONTRIBUTES TO MODULAR MISMATCH
• gt THIGH PAIN AND STRESS SHIELDING
  

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THA CEMENTLESS

• TYPES OF COATINGS
• 1. SINTERING
• 2. DIFFUSION-BONDING
• 3. PLASMA-SPRAYING

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TYPE OF COATINGS SINTERING

• SINTERING HIGH TEMP. PROCESS WHICH ALLOWS
  PARTICLE PARTICLE PARTICLE-SUBSTRATE BONDING
  AT CONTACT POINTS
• LOWERS FATIGUE STRENGTH
• UTILIZED IN COBALT CHROME AND TITANIUM STEMS

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TYPES OF COATINGS DIFFUSION BONDING

• RELATIVELY LOW TEMP.
• USED IN COMBINATION WITH PREASURE IN MANUFACTURE
  OF TITANIUM FIBER MESH
• WEAKENS STEM DUE TO NOTCH-SENSITIVITY EFFECT

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TYPES OF COATING PLASMA-SPRAYING

• PARTIAL MELTING OF METAL POWDERS IN A HOT PLASMA
  FLAME
• DELIVERY OF THE PRODUCT TO THE SUBSTRATE THROUGH
  A CARRIER GAS UNDER AN APPLIED ELECTRICAL FIELD
• LESS INTERCONNECTING POROSITY THAN SINTERED BEAD
  OR FIBER MESH
• ALSO DIMINISHED FATIGUE PERFORMANCE

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EVOLUTION OF PRESS FIT DESIGN

• THREE BROAD CATEGORIES
• 1. CYLINDRICAL
• 2. TAPERED
• 3. ANATOMIC
• TWO GENERATIONS OF
• EVOLUTION IN DESIGN

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FIRST GENERATION CYLINDRICAL

• CYLINDRICAL DESIGN DISTALLY
• RELY ON STABILITY FROM DISTAL PRESS FIT FIXATION
• EXTENSIVELY POROUS COATED
• USE MATERIALS OF HIGH STRENGTH
• USUALLY COLLARED

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SECOND GENERATION CYLINDRICAL

• EXTENSIVE SINTERED BEAD POROUS COATING
• BETTER PROXIMAL FIT
• DISTAL FLUTES
• CORONAL SLOTS
• POLISHED TIP

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FIRST GENERATION TAPERED

• LOAD FEMUR PROXIMALLY ONLY
• PROXIMALLY COATED
• TAPERED AP\MED-LAT
• TAPER SELF LOCKING
• NO COLLAR

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SECOND GENERATION TAPERED

• SINTERED BEAD COATING PROXIMALLY INSTEAD OF
  SINTERED SPRAY
• ROTATIONAL RIDGES
• POLISHED TIP

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FIRST GENERATION ANATOMIC

• INCREASED PROXIMAL FIT\FILL FOR STABILITY
• ANTEVERTED NECKS
• RIGHT AND LEFT CONFIGURATIONS
• BOASTS IMPROVED FEMORAL LOADING

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SECOND GENERATION ANATOMIC

• MOVED AWAY FROM BOWED TIPS gt CORR. THIGH PAIN
• FLATTENING POSTERIOR AND LATERAL SIDES

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HORIZONTAL PLATFORM STABILIZED

• LOADS CORTICAL ARC
• LATERAL FIN FOR ROTATIONAL STABILITY
• T-SHAPED TORQUE RESISTANT CROSS SECTION
• STRAIGHT STEM WITH TAPERED TIP

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MATERIALS AND METHODS

• THIRTY NINE PRIMARY THA WERE RETROSPECTIVELY
  EVALUATED
• ALL PROCEDURE PERFORMED BY ONE SURGEON OR UNDER
  DIRECT SUPERVISION OF THAT SURGEON
• TRANSLATERAL APPROACH WITH MALLORY SPLIT WAS
  UTILIZED WITH ANATOMIC ABDUCTOR REPAIR

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MATERIALS AND METHODS

• POST-OPERATIVELY
• 1. DVT. PROPH WITH LOW DOSE
• COUMADIN REGIMEN
• 2. NSAIDS STRICTLY AVOIDED
• DURING IMMEDIATE POSTOP
• COURSE
• 3. POST OPERTIVE REGIMEN WAS IDENTICAL IN
• ALL CASES WITH FULL WEIGHT BEARING
• BEGUN FIRST DAY AFTER SURGERY

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MATERIALS AND METHODS

• EVALUATED
• 1. HSS SCORES AT PREOP, 6WEEKS
• 6 MONTHS, YEARLY
• 2. THIGH PAIN VISUAL ANALOG
• 3. FINAL CLINICAL EVALUATION
• AT 5YRS

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RESULTS

• THRTY-EIGHT THA
• THIRTEEN PATIENTS DIED
• EIGHT RELOCATED UNABLE TO F/U FOR FINAL
  EVALUATION
• SEVENTEEN PTS WITH COMPLETE DATA
• MEAN AGE 71.5, RANGE 49-96

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RESULTS

• 17 PATIENTS at FIVE YRS
• 3-AVN ,1- RA ,13-OA
• 9 DORR TYPE C, 6 TYPE B, 2 TYPE A
• AVE PREOP HSS SCORE 41.6 WITH RANGE 9.9 73
• AVE POST-OP HSS 98 , RANGE 81-100
• ZERO PATIENTS HAVE UNDERGONE REVISION
• THIGH PAIN RATED ZERO IN 15 PTS AND LESS THAN ONE
  ON THE PATIENT SURVEY VISUAL ANALOG SCORE IN 2
  PTS

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CONCLUSIONS

• The HPS-II design of press fit stems provides
  positive results with regard to thigh pain and
  rates of revision regardless of bone morphology
• Elderly patients with type C bone are at greatest
  risk for intra-operative death related to
  cementing and are the patients in whom press
  fitting is ideally suited
• The study is limited due to population size but
  our results are encouraging.