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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 2001- Rhodes).

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JL. Lerat, C. Falaise LYON - France EFORT Congress (June 2001- Rhodes)

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  1. The results of cementless cups (HAP or Ti) with additional divergent pegs and acetabular reconstruction with graft in failed THAThe concept of “migration en bloc”(1993) JL. Lerat, C. Falaise LYON - France EFORT Congress (June 2001- 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 : 85 • Bone from reaming : 33 • Opposite femoral head : 1 Simple prolongation of the posterior incision

  9. Acetabular reconstruction } 93 % • Iliac crest autograft : 85 • Bone from reaming : 33 • Opposite femoral head : 1 • + Allograft : 1 femoral head : 43 2 femoral heads : 4 3 femoral heads : 2 • + bone substitute : 6 }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 pegs2 - 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 : 1 • Infections : 3 (recurrence for 3 of 11 previous infections)

  24. Operation Cup + stem 75 cases • Blood loss : 1075 ml ± 883 (100-4500) • Drainage : 650 ml ± 365(20-1900) • Op time : 192 min ± 60 (90-345) Cup alone 53 cases • Blood loss : 645 ml ± 534 (200-3400) • Drainage : 555 ml ± 293(20-1170) • Op time : 160 min ± 38 (90-300)

  25. Diameter of the cups Cases Removed cups : 49.6 mm + cement New cups : 55.9 mm Diameter of the cups

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

  27. Evaluation Radiographic measurements • 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 Postel-Merle d’Aubigné score (18 pts) 16.4 ± 2 / 18 • Excellent : 69 • Good : 29 • Fair: 10 • Poor : 1 • 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 : 3.3 • Zone I,II : 0.8 • Zone II,III : 1.6 • Zone I,II,III : 1.6

  33. Radiological resultsmanual 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 : 5 • Medial migration 2 to 4 mm : 2 > 4 mm : 7 • 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 measurementsScale adapted to the size of the implants

  36. Computerised measurements1) Ascension (1st measurement)

  37. Computerised measurementsAscension (2d measurement)

  38. Computerised measurements2) Lateralisation 1

  39. Computerised measurementsLateralisation 2

  40. Computerised measurements3) Inclination

  41. Computerised measurements4) 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) LongitudinalL1 - 2

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

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

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

  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 Hip centre correct : 43 % Position of the cup / U

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

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