PowerPointPrsentation

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METAL-TO-METAL FRICTION
R. Kotz, A. Kolb, W. Brodner, P. Bitzan, G.
Reinisch, F. Gottsauner-Wolf, V. Meisinger, A.
Kaider, R. Eyb, A. Grübl Department of
Orthopaedics, Medical University
Vienna Department of Occupational Medicine,
Medical University Vienna Institute for Medical
Computer Sciences, Medical university Vienna
Orthopaedic Department, Danube Hospital
Vienna
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Why Metal-on-Metal Articulations?

• Reduction of wear
• Longer prosthesis life
• Metasul metal-on-metal articulation, low wear,
  low friction (Weber, 1992, Z Orthop)
• Annual Metasul volumetric wear 60 times smaller
  than with PE cups (Sieber, 1999, JBJS-B)

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In a joint simulator test the Metasul
metal-on metal prosthesis produced a 100-fold
less wear debris than metal-on-polyethylene
prostheses
H.L. Anissian et al., Acta Orthop. Scand., 70,
1999, p. 578
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Why in-vivo Measurement of Serum Metals?

• X-rays inconclusive in wear detection (linear
  annual wear around 3 µm 5 µm / component)
• Investigation of biologic interactions with
  orthopaedic implants

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Orthopaedic Implants and Metal Release

• Metal release into serum and urine (Coleman,
  1973, Br Med J)
• Metal release into adjacent tissue (Willert,
  1977, J Biomed Mater Res)
• Metal dissemination to distant organs (Michel,
  1991, Arch Orthop Trauma Surg)

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Aim of the Study

• Systemic metal release from Metasul
  articulation?
• If yes, description of a reference serum cobalt
  concentration
• Uneventful hip arthroplasty
• Baseline for further observations

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Patients and Methods

• Prospective study (1 year and 5 years)
• 100 patients
• Indication for surgery
• Osteoarthritis
• AVN of femoral head

• No selection of
• Additional orthopaedic implants
• Dental prostheses with metal bars
• Osteoarthritis of other joints
• Rheumatoid arthritis

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Patients and Methods

• Alloclassic total hip arthroplasty
• Stem forged Ti-6Al-7Nb
• Cup commercially pure Titanium
• Cementless fixation
• 50 patients ceramic-on-PE
• 50 patients (Metasul)
• Articulation only prosthesis variable

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• Nov.92 to May94

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Metasul Articulation

• Wrought Co-28Cr-6Mo-0,2C
• 0,2 C (block carbides embedded in metal
  surface, better lubrification)
• Morsed taper
• Cup inlay with PE liner
• Only source of cobalt in patients

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Patients and Methods

• Metal-on-Metal group
• Mean age 58,3 years (16 81)
• 31 female / 19 male
• Ceramic-on-PE group
• Mean age 62,0 years (26 87)
• 39 female / 11 male

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Atomic Absorption Spectrometry

• Perkin Elmer 5100-ZL
• AS-70 autosampler
• Graphite furnace
• Wavelength 242,5 nm
• Temperature 2300C

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Atomic Absorption Spectrometry

• Calibration by standard solutions
• Samples analysis single-blinded
• Triplicate analysis
• Detection limit of cobalt in serum 0,3 µg/l in
  our laboratory

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One year Results

• Brodner et al. JBJS-B (1997)
• 55 patients after one year
• Metasul articulation generates a systemic cobalt
  release
• Median serum concentration of 1,1 µg/l after
  one year
• Highly significant difference to ceramic-on-PE
  group (lt 0,3 µg/l)

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Results

• Median serum cobalt of metal-on-metal group
  between 0,5 µg/l and 1,0 µg/l (1 chinese in
  china) during 5 years period
• Median serum cobalt of ceramic-on-PE below
  detection limit

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Case 1 High Cobalt level with exercise and
urine excretion
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Case 2 renal failure and cobalt level

• Peak serum cobalt of 119,2 µg/l
• Patient with SLE
• Chronic renal failure after kidney
  transplantation
• Gradual increase of serum cobalt with increase of
  serum creatinine

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Case 3 Cobalt level and haemodialysis

• Patient with hereditary renal disease
• Peak serum cobalt of 105,1 µg/l under
  haemodialysis
• Decline of serum cobalt after NTX and sufficient
  renal function
• Increase of serum cobalt after renal transplant
  failure (HvG)

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Conclusion

• Systemic cobalt release from Metasul
  articulation
• Reference median serum cobalt concentration in
  uneventful THA 0,5 µg/l 1,0 µg/l
• Environmental and occupational cobalt load
  neglectable in our patients
• Chronic renal failure restricts cobalt
  elimination in urine

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5 yrs Results
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Cup Inclination and Serum Metal Levels

• Material and Methods
• 309 Patients (172 f, 137m) operated from IX/95
  to XI/98 were studied after exclusion of all
  patients who could bias the results like
  bilaterally treated patients ore those carrying
  other orthopaedic implants.

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Cup Inclination and Serum Metal Levels

• Material and Methods
• Cup inclination was measured on ap postop.
  radiographs drawing a line adjacent to the
  ischial tuberosity and another adjacent to the
  acetabular component

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Cup Inclination and Serum Metal Levels

• Material and Methods
• Three groups of 20 patients each were
  established representing inclination angles of
  55-63 (mean 58), 44-46 (mean 45) and 23-37
  (mean 33)
• All patients were seen at a follow-up visit
  between may 2001 and march 2002.

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Cup Inclination and Serum Metal Levels

• Results
• Mean serum cobalt 1.6 µg/l (0.15 - 6.8µg/l)
• Mean serum chrom. 2.3 µg/l (0.15-33.6µg/l)
• At follow-up visit 4.3a (2.73-6.0a) after index
  operation

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Cup Inclination and Serum Cobalt Levels
µg/l
Serum Cobalt Degrees
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Cup Inclination and Serum Chromium Levels
µg/l
Serum Chromium Degrees
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Cup Inclination and Serum Metal Levels

• Results
• Mean HHS 92.5 (52.8-100).
• Mean UCLA Score 6.16 (2-10).
• Mean Body Mass Index 28.5 (21.3-44.5).

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Cup Inclination and Serum Cobalt Levels

• No statistically significant correlation could
  be calculated between the three groups of cup
  inclination and elevated serum cobalt and
  chromium levels (p0.234 and 0.130).
• However 3 young (37, 47 and 55a) and active
  (HHS100, UCLA 6, 7 and 9) female patients had 3
  to 16-fold elevated serum cobalt, 4.5 to 16-fold
  elevated chromium levels with inclination angles
  from 58 to 63.

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Test wear
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Carbides
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Third particles
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Material CoCrMo HC ? LC ?
ASTM F 1537 (since 2000)

• LC low carbon C lt 0,14
• HC high carbon 0,15 lt C lt 0,35

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Material carbon content carbides

• LC low carbon small few carbides
• HC high carbon not always (!) bigger (8 µm)
  more carbides

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Material carbides, HC wrought alloy
A. Wang, Wear 1999
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Material carbides, LC wrought alloy
A. Wang, Wear 1999
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Material carbides, cast alloy
A. Wang, Wear 1999
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Wear characteristics micro pits
C. Rieker, ASTM STP 1346, 1998
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Wear particles metallic debris in tissue
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Amount of wear linear volumetric
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In-vivo wear rates running in wear
0,51 mm³/a
3,9 mm³
G. Reinisch, Biomat. 2003
G. Reinisch, Biomat 2000
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Introduction
Metasul Head carbides BMF-Wien, G. Reinisch
EDX Analysis carbides bulk
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Resistance to third body wear? A self-healing
surface?
Third body wear BMF-Wien, G. Reinisch
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Friction
Protein adhesion BMF-Wien, G. Reinisch
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Hypersensitivity?
By now there is no generally accepted test for
metal hypersensitivity to metal implants. A
correlation of elevated serum Co and Cr
concentrations and lymphocyte reactivity,
suggests a cell-mediated hypersensitivity
reaction Hallab et al., 2004.
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Hypersensitivity?
More lymphocytes in periprosthetic tissues of
metal-on-metal implants compared to
metal-on-polyethylene implants Campbell et al.,
2002 Lymphocytic infiltration, presence of
plasmacells and fibrinexudation in patients with
failed metal-on-metal total hip implants was
reported Willert et al., 2005
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Journal Bone Joint Surg, 88-B 2006
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Journal Orthop.Research, 2007
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Long-term Study 10 yrs Results

• Patients
• 105 first cases with Metasul
• Nov.92 to Mai94
• 54 f (57a), 44 m (54a)

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Long-term Study 10 yrs Results

• 15 patients (14.2)
• 8 patients lost to follow-up (7.6)
• 2 patients interviewed on the phone
• 80 patients at clinical follow-up
• 76 x-rays available
• 22 blood samples of patients with unilateral THR
  in absence of any other metallic implant

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Long-term Study 10 yrs Results

• HHS 92.0 points (43.8 to 100)
• UCLA Score 6 points (1 to 10)
• 2 revisions 1 for (late) infection, 1 for
  recurrent dislocation
• No case of aseptic loosening

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Osteolysis cup (serum cobalt 50.8 µg/l)
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Long-term Study 10 yrs Results

• Serum levels
• Median of serum cobalt at 10 years
• 22 unilateral cases w/o any other metal implant
• Cobalt 0.75 µg/L (0.3 to 50.8 µg/L)

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Long-term Study 10 yrs Results

• Renal function
• No impairment of kidney function at 10 years
• Median creatinine 0.88 mg/dl (preOP 0.87 mg/dl)
• Median BUN 16.4 mg/dl (preOP 14.4mg/dl)

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Long-term Study 10 yrs Results

• Malignancies between surgery and follow-up
• 2 cases of colon cancer
• 1 case of breast cancer
• 1 cancer of unknown primary
• 1 case of CLL
• This complies with the expected incidence rate of
  malignancies for the given period and number of
  patients

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Long-term Study 10 yrs Results
Survival rate
98.6 (95c.i.96-100)
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Long-term Study 10 yrs Results

• Conclusion
• Minimum 10 a results of 105 cases.
• No aseptic loosening
• Survival rate 98.6
• No increase of serum metal when compared to 5 a
  data
• Serum cobalt and chromium levels did not alter
  renal function

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Long-term Study 10 yrs Results (cont.)

• Conclusion
• No higher rate of malignacies in our study group
  although number of patients was relativly small
• Some radiolucent lines and osteolytic lesions in
  zones 1,7,8,14, I,II,III
• We expect even better results as we already
  published with 15 yrs of Alloclassic
  ceramic-polyethylen with 95 survival