ACTUAL SITUATION OF METALONMETAL ARTICULATIONS

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ACTUAL SITUATION OF METAL-ON-METAL ARTICULATIONS
C.B. Rieker, PhD Zimmer GmbH Switzerland
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ACTUAL SITUATION OF METAL-ON-METAL ARTICULATIONS

• Analysis of retrievals
• Clinical results
• Cemented cups
• Uncemented cups
• Allergy
• Conclusions

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SECOND GENERATION OFMETAL-METAL ARTICULATIONS

• 792 METASUL retrieved components(435 revisions
  - 412 heads - 380 cups)
• Manufactured by Zimmer GmbH
• Wrought Co-28Cr-6Mo-0.20C alloy(ASTM F-1537 /
  ISO 5832-12)
• Head diameters 28 mm (98.3) 32 mm (1.7)
• Implantation time 1 month - 185 months (mean
  follow-up 53 months)

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METASUL RETRIEVALS
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SECOND GENERATION OFMETAL-METAL ARTICULATIONS
MEAN WEAR RATEWHOLE BEARING

• First year (running-in wear) 28.3 µm
• Second year 10.5 µm/year
• After the second year 5.8 µm/year

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ACTUAL SITUATION OF METAL-ON-METAL ARTICULATIONS

• Analysis of retrievals
• Clinical results
• Cemented cups
• Uncemented cups
• Allergy
• Conclusions

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C. NICH ET ALRCO, 92, 2006, P. 118

• METASUL Müller cemented cups
• 28 cases (23 patients) between December 2000 and
  June 2003
• 10 men / 13 women
• Mean age 44.7 years (22 59)
• Mean follow-up 31 months (12 47)

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C. NICH ET ALRCO, 92, 2006, P. 118

• One patient (one hip) lost to follow-up
• One hip revised at 5 months for deep infection
• All hips were rated excellent or very good
• Radiographically, seven 7 hips (27) had a
  progressive acetabular radiolucent line

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C. NICH ET ALRCO, 92, 2006, P. 118

• Theses acetabular radiolucent lines were located
  at the bone-cement interface and were linked with
  small cups.
• It is hypothesized that the diminution of the
  polyethylene thickness has led to an increased
  rigidity of the cup, resulting in higher stresses
  at the bone-cement interface.

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J. GIRARD ET ALRCO, 94, 2008, P. 346

• METASUL Müller / Weber cemented cups implanted
  with a reinforcement ring
• 23 cases (22 patients) between January 1998 and
  December 2004
• 6 men / 16 women
• Mean age 44 years (24 56)
• Mean follow-up 5 years (3 8)

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J. GIRARD ET ALRCO, 94, 2008, P. 346

• No revision in any patient for failure of the
  acetabular fixation
• The mean PMA score improved from 12.9 to 17.5
  points (16 18)
• The radiographic analysis did not reveal any sign
  of lucency between the cup and ring
• There was no evidence of femoral osteolysis but
  one femoral revision was needed (fracture of the
  femur)

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J. GIRARD ET ALRCO, 94, 2008, P. 346

• In our study, the large number of small cups
  (57) would have been expected to produce a high
  rate of acetabular lucent lines, as recently
  published.
• Cemented the metal-on-metal cup into a
  reinforcement ring can avoid the risk of
  loosening observed after direct cemented into
  bone.

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ACTUAL SITUATION OF METAL-ON-METAL ARTICULATIONS

• Introduction
• Analysis of retrievals
• Clinical results
• Cemented cups
• Uncemented cups
• Allergy
• Conclusions

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A. GRÜBL ET ALJ ORTHOP RES, 25, 2007, P. 841

• METASUL with Alloclassic system
• 105 cases (98 patients) between November 1992 and
  May 1994
• Minimum follow-up 10 years

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A. GRÜBL ET ALJ ORTHOP RES, 25, 2007, P. 841

• Four re-interventions
• One for fracture of the greater trochanter after
  3 ½ years
• One for pararticular ossification
• One for post-traumatic recurrent dislocation
• One for late infectionImplants revised
• The probability of a revision-free implant
  survival time of 10-years post-operation was
  98.6 (95 confidence interval 96 100.)

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A. GRÜBL ET ALJ ORTHOP RES, 25, 2007, P. 841

• At greater than 10 years follow-up, the average
  Harris hip score was 92 (range 43.8 100 points)
  and the average UCLA score was 6 (range 1 10
  points).
• Our radiographic data do not give evidence of
  early osteolysis with an all high carbon content
  second generation metal-on-metal articulation.

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ACTUAL SITUATION OF METAL-ON-METAL ARTICULATIONS

• Analysis of retrievals
• Clinical results
• Cemented cups
• Uncemented cups
• Allergy
• Conclusions

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METAL-ON-METAL TOTALHIP ARTHROPLASTYTHE CONCERNS

• A causal link with metal-on-metal implants and
  elevated ions and subsequent development of
  cancer or other medical problems has not been
  shown.
• S.J. MacDonald, CORR 429, 2004, p. 86

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CLINICAL IMPLICATIONS
Malignant diseases?
Immunological responses?
Pregnancy?
Chromosome abnormalities?

• The Medicines and Healthcare products Regulatory
  Agency (MHRA) of Great Britain asked advice to an
  independent expert advisory group (EAG) in
  September 2006.
• The conclusions of the EAG have been published in
  January 2, 2008.

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BRITISH MHRAEXPERT ADVISORY GROUP ON THE
BIOLOGICAL EFFECTS OF METAL DEBRIS
Published on-line January 2, 2008

• There is no evidence for any association between
  hip replacements and an increased incidence of
  any malignant disease.
• There is no evidence that the genotoxic effects
  seen in patients with metal-on-metal hip
  replacements are associated with increased levels
  of cobalt and chromium ions.

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BRITISH MHRAEXPERT ADVISORY GROUP ON THE
BIOLOGICAL EFFECTS OF METAL DEBRIS
Published on-line January 2, 2008

• There is no evidence that increased levels of
  cobalt and chromium ions are associated with any
  clinical effects.
• While there is evidence for an immunological
  component in some, rarely seen, responses to wear
  debris, the precise mechanisms of the effects
  observed are unknown.

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ALVALAseptic Lymphocytic Vasculitis-Associated
Lesions
Second SYNOS Workshop on Immune Reaction to CoCr
ImplantsProf. R. Zinkernagel - September 17,
2001
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LYDIA LYmphocyte-Dominated Immunological Answer
Prof. H.-G. Willert - JBJS 87A, 2005, p. 28
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METAL-ON-METAL BEARINGS AND HYPERSENSITIVITY IN
PATIENTS WITH ARTIFICIAL JOINTS

• Our findings suggest that lymphocytic
  infiltration may also occur in the tissues around
  other cobalt-chrome-molybdenum-containing
  implants. Therefore, the reaction seen with these
  metal-on-metal articulations is not a new
  phenomenon.
• H.-G. Willert et al., JBJS, 87-A, 2005, p. 28

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ACTUAL SITUATION OF METAL-ON-METAL ARTICULATIONS

• Analysis of retrievals
• Clinical results
• Cemented cups
• Uncemented cups
• Ions
• Conclusions

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TAKE HOME MESSAGES

• Proven in-vivo low wear rate (6 µm/year)
• Excellent clinical results with cemented cups
  implanted with a reinforcement ring
• Excellent clinical results with uncemented cups
• Allergic reactions are rare and are not specific
  to metal-on-metal bearings

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THANK YOU