1. JL. Lerat, C. Falaise LYON - France EFORT Congress (June 2001- Rhodes)
The results of cementless cups (HAP or Ti) with additional divergent pegs and acetabular reconstruction with graft in failed THA The concept of “migration en bloc” (1993)
JL. Lerat, C. Falaise
LYON - France
EFORT Congress (June Rhodes)

2. Special Cup with pegs for revision 1st model : «Spring» ( Landanger-Depuy 1993 - 2000 )
Metallic cup ( Ti ). Hydroxyapatite coating
6 holes for 6 pegs fixed with the cup by threading
Alumine on polyethylene

3. 1rst model (alumine on polyethylene) : 128 cases
6 divergent pegs bring usually a good primary stability
: 10 and 15 mm (in the majority of the cases)
or 20, 25, 30 mm

4. The most frequent cause of revision is cemented cups with bone defects corresponding to the amount of cement: 91 cases

5. Revision of non-cemented cups : 29 cases

6. Revision of cemented acetabular rings previously used for revision : 4 cases

7. Material 128 acetabular revisions (11 infected) 75 complete revisions
Previous operations : 1 to 8
Previous surgery : 9.8 ± 5 years
Females : 88
Mean age : 64.4 ± 11 Ys
Mean follow-up : 4.6 y ± 1.7 (1 to 7 y)
One surgeon, one technique

8. Acetabular reconstruction
} 93 %
Iliac crest autograft :
Bone from reaming :
Opposite femoral head : 1
Simple prolongation of the posterior incision

9. Acetabular reconstruction
} 93 %
Iliac crest autograft :
Bone from reaming :
Opposite femoral head : 1
+ Allograft :
1 femoral head : 43
2 femoral heads :
3 femoral heads :
+ bone substitute :
} 38 %
Iliac crest is grafted : 38 cases

10. Prolongation of the posterior approach toward the posterior iliac crest

11. Prolongation of the posterior approach toward the posterior iliac crest
Preservation of the vascularisation and inervation of the muscle

12. Prolongation of the posterior approach toward the posterior iliac crest
Preservation of the vascularisation and inervation of the muscle

13. Prolongation of the posterior approach toward the posterior iliac crest
Preservation of the vascularisation and inervation of the muscle

14. Paprosky : Type I (n = 31)
Easy cases : graft into the holes, sufficient contact of the cup with the host bone

15. Paprosky : Type II (n = 63) A (n = 20) B (n = 22) C (n = 21)
The cup may be stabilised between the 2 columns
Press-fitting the acetabular component is often possible
1 iliac crest is sufficient

16. Paprosky : Type II (n = 63)
- Autograft into the holes and for the roof reconstruction - Bone is impacted with the « trial cup »
- Stabilisation by press-fitting the cup between the 2 columns + 6 pegs

17. Paprosky : Type III (n = 32)
III A (n = 22) III B (n = 10)
Massive bone graft is necessary for the reconstruction of :
- the centre
- the columns
- the roof

18. The reconstruction of a column is made after the cup has been fixed to the host bone and to the graft
1 - Fixation of the component with pegs 2 - Spongious autograft is placed on the HAP coating
3 - The bone block is then fitted on the cup by 1 or 2 pegs
(or 1 adjusting srew) inside outside

19. The use of screws is not recommended usualy
Adjusting screws may be used to fit the graft against the cup
Or for the primary stabilisation of the cup
It is recommended to replace the screws by pegs for definitive fixation

20. Stability of the implants
Press-fit alone : 45
Stability attained by the use of pegs : 83
The divergent pegs bring a complementary stability to cup

21. Stability of the implants
6 years
The stabilisation of the cup is obtained with graft incorporation
and remodelling under load-bearing conditions

22. Weight load-bearing
Immediate (partial) : 25 4 to 6 weeks : 48 2 to 3 months : 55

23. Complications Dislocations (2 first months) : 9
Trochanteric non-unions : 6
(4 had previous non-unions)
Ossifications :
Infections :
(recurrence for 3 of 11 previous infections)

24. Operation Cup + stem 75 cases Cup alone 53 cases
Blood loss : 1075 ml ± ( )
Drainage : ml ± ( )
Op time : min ± (90-345)
Cup alone cases
Blood loss : 645 ml ± ( )
Drainage : ml ± ( )
Op time : min ± (90-300)

25. Diameter of the cups Cases Removed cups : 49.6 mm + cement New cups :

26. Removed cups : 49.6 mm + cement New cups : 55.9 mm Cement Bone graft
The mean diameter of the new cups increases, but the cement is replaced by bone graft
Cement Bone graft

27. Evaluation Radiographic measurements Functional value
Incorporation /radio lucent line
Stability in the 3 planes
- Numerised X-rays
- Precise measurements
(special software : “MetrOs” C. Falaise)
Functional value
PMA Score (Postel - Merle d'Aubigné)

28. Lost for follow-up : 3 Deceased : 8 Revisions : 11
Loosening : 9
Infection : 2
Patients reviewed : 102

29. Results 16.4 ± 2 / 18 Postel-Merle d’Aubigné score (18 pts)
16.4 ± 2 / 18
Excellent : 69
Good :
Fair:
Poor :
Impossible to estimate : 27
The results are also influenced by the status of the femur

30. Results
The results are good for the 3 types of Paprosky

31. Results Complete healing : 94 Pain at the iliac crest : 3
Poor active abduction : 22

32. Radio lucencies None : 87.7 % Zone I : 3.3 Zone II : 1.6
Zone III :
Zone I,II :
Zone II,III : 1.6
Zone I,II,III : 1.6

33. Radiological results manual measurements (Failed cases included)
86 % of the implants are stable at visual examination no migration, no radio-lucent line
Vertical migration
2 to 6 mm : 3
> 6 mm :
Medial migration
2 to 4 mm : 2
> 4 mm :
Verticalisation : 5.5 %
Important displacement : 7 cases
Revised by the same cup : 5

34. Computerised measurements
Scanner Vidar
Definition : 150 Dot per inch
Selection 1 Pixel : 0.17 mm
Special software «MètrOs» (C. FALAISE)
Navigation into the image with magnification
Adjustment of the luminosity and contrast
Scale adapted to the size of the implants
Geometric constructions and calculation of index automatically
« EBRA » method (Krismer - Innsbruck)
6 index (3 longitudinal, 3 transversal)
11 measurements
Accuracy : 0.7 mm

35. Computerised measurements Scale adapted to the size of the implants

36. Computerised measurements 1) Ascension (1st measurement)

37. Computerised measurements Ascension (2d measurement)

38. Computerised measurements 2) Lateralisation 1

39. Computerised measurements Lateralisation 2

40. Computerised measurements 3) Inclination

41. Computerised measurements 4) Version
sin(a) = Rp/Rc
a = sin-1(Rp/Rc)

42. « EBRA » method Krismer et coll. 1995 (Innsbruck)
Control of mistakes due to incidence variations
Comparability of 2 films by measuring the position of constant anatomical landmarks
Difference in size = Comparability Index
For an index limited to 3 mm, the precision is ± 0.7 mm for the experimental model and ± 1 mm in clinical study

43. Comparability of 2 films by measuring the position of constant anatomical landmarks
6 index (3 longitudinal, 3 transversal)
Longitudinal L1 - 2

44. Comparability of 2 films by measuring the position of constant anatomical landmarks
6 index (3 longitudinal, 3 transversal)
Longitudinal L2 - 3

45. Comparability of 2 films by measuring the position of constant anatomical landmarks
6 index (3 longitudinal, 3 transversal)
Transversal M1 - 2

46. Comparability of 2 films by measuring the position of constant anatomical landmarks
6 index (3 longitudinal, 3 transversal)
Transversal M 2 - 3

47. Computerised measurements
Inclination and anteversion of the cups
Post-op
Inclination : 49° ± 7,5
Anteversion : 17.1° ± 9.9
Follow-up : 4 years
Inclination : 48.7° ± 9.8
Anteversion : 19.5° ± 12.4

48. Computerised measurements
Position of the cup / U ligne
Position of the cup / U
Hip centre correct : 43 %

49. Migrations Migrations = 45 % with computerised measurements
= 14 % visual method (migrations > 3mm)
Literature : maxi 9 %
Callaghan 9 % 4 years (JBJS 1985)
Kavanagh 9 % 4.5 years (JBJS 1985)
EBRA is the best method to detect migrations
(except RSA : roentgen stereophotogrammetry)
Ilchmann T. J. Arthroplasty 1992

50. Post op 6 months Stable after 1 year
1 example of verticalisation and ascencion
Post op months Stable after 1 year

51. Stable Migration Total
type
type 2A
type 2B
type 2C
type 3A
type 3B

52. Postop 1 year The stability of a cup is achieved by bone remodeling.
We consider that a small migration is a normal phenomena
(proved by computerised measurements)
Postop year
Consequences of migation when using screws = wear or screw fracture

53. Mobility between the cup and the screws has consequences :
Impression in the polyethylene
±  metallic wear 
± fractures of the screws

54. The concept of “migration en bloc”
The pegs tend to limit the migration of the cup but should this occur, they migrate together in the same direction

55. Failed revision Successfull revision Only 3 pegs with 6 pegs
5 cups placed with screws failed and they had been revised with a similar cup with pegs
Failed revision Successfull revision Only 3 pegs with 6 pegs
+ 5 years

56. 5 years
5 ans

57. 5 years

58. 6 years

59. 13 infected cases Two-steps revision
3 recurences of infection finally healed

60. The limits of this cup Type 4 Destruction of the roof and 2 columns
+ destruction of inferior bone

61. What can we do for large defects « type 4 » ?
Failure of a 1rst revision using a cemented ring (Kerboul) Protrusio (6 years later)

63. Granuloma + cement

64. The host bone and the cancellous bone graft cannot find any possibility of ingrowht on this surface

65. Wagner’s acetabular ring for revision and massive bone graft
Ti-6Al-7Nb Protasul TM
Cementless and metal on metal

66. A part of a femoral head is placed in the defect

67. Cortico-spongious blocks to reconstruct the columns and the roof

68. Spongious morsellised bone (auto and allo graft) cover the precedent graft

69. The Wagner ’s ring is impacted and fixed with screws

70. heads + 80 cc of morsellised bone graft
Acetabular reconstruction with 3 femoral
heads + 80 cc of morsellised bone graft

71. The new Wagner’s ring (for type 4)
2 advantages : cementless ( Ti coating for bony integration )
and metal on metal
1 drawback : Migration is bound to happen ( problem with the screws)
pegs for future ??

72. Some examples of « Spring » cup
Failure of other kinds of revision rings

73. 4 years
Failure of other kinds of revision rings

74. Op. 5 4 previous operations Op. 2 Op. 3 Op. 4 1 iliac crest +
1 femoral head
Face + 5 ans

75. Op. 5 1 iliac crest + 1 femoral head
7 years
Op iliac crest + 1 femoral head

76. The polyethylene debris are responsible for the loosening of the THA
Foreign bodies Granulomas

77. Acetabular reconstruction is often associated with femoral problems

79. Polyethylene and metal-back must be eradicated

80. Polyethylene must be replaced by better materials
Alumina on alumina
Alumine - alumine
Alumine - polyéthylène
Metal on metal
Zircone - zircone

81. - Ti-6Al-7Nb Protasul Cup with pegs 2d generation
(Cedior-Sulzer)
- Ti-6Al-7Nb Protasul
- 7 pegs
- Metal / metal (metasul)
54 cases (since 6/2000)

82. 11 months
Follow-up < 1 year

84. Conclusions 10 m Incorporation-stability of the cup :
success rate : 96 % in types 1,2,3
(follow-up : 1 to 7 years)
Restoration of bony structures :
autograft ++ or auto + allograft

85. Conclusions Usefulness of non cemented cups (HAP or Ti)
Interest of the pegs fixed to the cup
Pegs are preferable to screws
Pegs do not interfere with small migration during osteo-integration