This document summarizes information about hip resurfacing arthroplasty. It discusses how resurfacing is best for young, active patients with good bone quality who want to conserve bone and soft tissues. However, it notes that resurfacing is not suitable for all hips. Certain factors can make a hip unsuitable for resurfacing, like severe deformity, cystic changes, or an excessively anteverted neck. The main contraindication is osteonecrosis with collapse of the femoral head. It concludes that patients must have realistic expectations, and surgeons need to have an alternative plan in case resurfacing is not possible.

1. Η ΧΕΙΡΟΥΡΓΙΚΗ ΤΟΥ ΙΣΧΙΟΥ
ΣΗΜΕΡΑ

2. Weak Link
Complications - 1970 ’s
Loosening - 1980’ s
Wear - 1990’ s

3. Limiting Factors In T.H.A
• Wear
• Biological reaction to wear debris
Teflon → Polyethylene

4. Cement disease
Jones & Hungerford 1987

5. • particle disease
- HDP the main culprit
• particle access disease
Manley 2002

6. The Goal
• Improve wear characteristics
• Decrease particle load
• Minimize osteolysis

7. Choices
1. Crosslinked Polyethylene
2. Metal on Metal
3. Ceramic on Ceramic
Wear is the ultimate issue

8. Highly Crosslinked Polyethylene
• ↓ wear
• ↓ fracture toughness
• more vulnerable to
abrasive environment

9. Highly Crosslinked Polyethylene
↓ fracture toughness associated with an
increased number of particles
and
an increased number in the biologically
active range
“Watch this space”

10. Ceramic on ceramic
• alumina must be of high quality
(roughness/sphericity)
• tight tolerances must be maintained in the
manufacture of the bearing surfaces
• clearance must be <10 µm

11. Ceramic on Ceramic
Advantages
1. Wear reduction
2. Extreme hardness → scratch resistant
3. Low co- efficient of friction
4. Hydrophilic → improved lubrication
5. Use of large femoral heads
6. No potential for metal ion release

12. Technical Issues
Ceramic Rim Protection
1. Critical design issue
2. Avoids ceramic impingement

ceramic chipping
femoral neck notching

13. Socket Preparation
• 40 – 45 % abduction
• 25° anteversion
• 15° femoral stem anteversion

14. Femoral Component Selection
• Reduced femoral neck diameter
• Variable offset to maximize stability

15. Femoral Head Placement
• Use only with design specific femoral stem
• Clean trunion
• Fully seated before impaction
• Think pre- op about femoral neck length

16. Ceramic Concerns
1. Wear, lysis, surface damage
2. Modular complications
1. ceramic chipping
2. Non – concentric locking
3. Taper limitations
4. Fewer options of neck lengths

17. Ceramic Concerns
Rim wear
Impingement
Metal debris
Neck notching
Limited ROM
Stripe wear
Pull-out and re-polishing
Self limited ?
Progressive?

18. Ceramic Concerns
Fractures
Zirconia problem
Ceramic recalls
Head fracture leads to complicated revision
Retained debris can damage trunion
Retained debris can damage surfaces
Avoid the use of polyethylene

19. Clinical Results
328 hips
2/3 Ceramic bearings
1/3 Metal – Polyethylene
7 years follow –up
Ceramic on Ceramic
Revision rate 2.7%
Osteolysis 1.4%
Metal on polyethylene
Revision rate 7.5%
Osteolysis 14% Capello, 2005

20. 1978 - 2000
• > 3000 Al/Al couples
– 1 # head
– 1 # socket
Witvoet 1999
• 1763 femoral heads
– 1 # (0.06%)
Fritz and Gleitz 1996

22. Metal on Metal couple
1938

23. Metal on Metal Bearings
In 1938 one of the earliest total
hip replacements used an implant
with a metal-on-metal articulation

24. These early replacements were
doomed to failure in the face of
biological, tribological and
biomechanical incompatibility

25. Large bore metal-on-metal articulations
• McKee Farrar
• Ring
• Muller

26. Poor early results
• failure of implant fixation
• poor tolerances
• equatorial bearing

27. • later implants had better
tolerances and polar bearing
• good long term results with
excellent wear characteristics

30. The 20 year survivorship for McKee
Farrar prostheses with good
sphericity and polar contact was
better than the Charnley LFA
(77% compared with 73%) with
similar Harris hip scores
Jacobson et al 1996

31. Volumetric wear McKee Farrar 5-6mm3/year
vs Charnley LFA 50mm3/year
Walker et al 1974

32. • resurgence of interest in metal-
on-metal couples
• > 300,000 hip replacements with
metal-on-metal articulation
implanted in the last decade

33. METAL-ON-METAL
• decreased volumetric wear
• increased number of particles
15
mm3/million cycles
10
5
0
HXL UHMWPE Ceramic on Metal on metal
ceramic
280,000 PE particles generated per step
450,000 metal particles generated per step Fisher et al 2005

34. • the biological implications of
elevated metal levels in the blood
and urine remain the most significant
concern about MoM couples
• there is no established toxicity
threshold for the degradation
products of cobalt alloy implants
Jacobs et al 2004

35. • Hypersensitivity
Hallab et al 1994
• Toxicity
Jacobs et al 1999
• Genetic damage
Singh et al 1998
Luo et al 1996
• Carcinogenicity
Visuri et al 1996
Gillespie et al 1996
McGregor et al 2000

36. HYPERSENSITIVITY
Periprosthetic tissue harvested from
• 29 MoM
• 9 CoCr on polyethylene
• 10 titanium on polyethylene THRs
and analysed histologically and with
quantitative stereological analysis

37. Tissues obtained from the
MoM hips exhibited
• perivascular infiltration of
lymphocytes
• accumulation of plasma cells
associated with macrophages
containing metal particles
• increased surface ulceration
Davies et al JBJS 2005

39. TOXICITY
• Huk et al (2004) demonstrated in vitro
that Co2+ and Cr3+ ions induced cell
death by either apoptosis or necrosis
dependent on the ion concentrations
and the incubation time

40. GENETIC DAMAGE
• assessed change in metal levels
and chromosome aberrations
within two years of receiving MoM
hip arthroplasties
(6, 12 and 24 months)

41. • high resolution ICPMS for Co, Cr & Mo
• detection limits 0.2ng/ml for all three
metals
• FISH – with painting of chromosomes
1, 2 and 3

42. • significant increase of cobalt and
chromium concentrations
• significant increase in chromosome
translocations and aneuploidy in
peripheral blood lymphocytes at 6, 12
and 24 months after surgery
Ladon et al J Arthroplasty 2004

44. • evidence of cumulative mutagenic
damage in patients undergoing
revision THA compared with primary
hip arthroplasty as controls
• FISH with chromosome painting

45. Doherty et al JBJS 2001

46. Translocation

47. Aneuploidy

48. CARCINOGENICITY
• no epidemiological evidence to
suggest that there is any increased
risk of carcinogenesis

49. CONCLUSION
• wear debris damages chromosomes in
a dose dependent manner
Daley et al JBJS 2003

50. CONCLUSION
• hypersensitivity may introduce a novel
mode of failure
Willert et al JBJS 2005

51. There may be significant differences
between wear particles in vitro and in
vivo

52. • in serum metal particles are coated
with protein derivatives and are
identified as “self“
• not phagocytosed by macrophages

53. Case et al (JBJS 1994) wide dissemination of
metallic debris from implants
• local and distant lymph nodes, bone
marrow, liver and spleen
• levels higher with worn implants
• Co x 2,000, Cr x 362 in lymph nodes
Co x 45,000, Cr x 4,580 in bone marrow

54. • biological implications not fully
characterised
• clinical effects not defined
- particle mediated disease
(eg asbestosis) has a long latency

55. Metallic wear debris can damage
chromosomes
• dose dependent
• damage specific to the type of metal

56. Ongoing programme of research
to identify
• corrosion products
• transport mechanism
• toxicity threshold
• excretion
• surface characteristics
etc, etc

58. Revisiting Surface Arthroplasty
The evolution of
hip resurfacing
arthroplasty
Smith Petersen Peter Grigoris et al.2005

59. Conservative
philosophy
minimally invasive surgery
- conserving bone
- conserving soft tissues

60. Who?
•Young, active patients
•Good bones
•All ask in the UK !

61. Surgical Technique
•Pre-op assessment – planning
•Appropriate surgical technique

73. Practical limitations of hip
resurfacing arthroplasty

74. Bristol Study
•61 consecutive hips in 57
patients
•mean age 35 years (range 17-
49)
•28 female - 29 male

75. Diagnosis
DDH 17
AVN 15
OA 13
SUFE 5
Perthes 2
Other 2

76. 58 total hip replacements
and 3 thrust plates

77. Templates and guidelines used to
assess suitability for resurfacing on the
pre-operative x-rays

78. Three groups identified
A suitable for resurfacing 28
B unsuitable for resurfacing 26
C hips that would present real
technical difficulties at
resurfacing 7

79. Factors for a hip being unsuitable
• severe deformity of the head itself (±
collapse)
• severe cystic changes in the head and
neck
• no functional femoral head
• an excessively anteverted femoral neck

80. Contra – indications
Pathology
Morphology
Biomechanics

81. The main contra - indication
Osteonecrosis with collapse and
extensive involvement of the head

84. Conclusions
•resurfacing arthroplasty is not suitable
for all hips
•patients need to have realistic
expectations
•the surgeon needs to have plan B
available at the time of operation

86. Warning ! ! !
Don’t stretch the indications
Avoid commercial innovations
MIS is speculative terminology
RTTS is for surgeons
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