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Charnley-Kerboull Total Hip Replacement Long Term Results In Patients Younger Than 50 Results of a 30 years experien

Charnley-Kerboull Total Hip Replacement Long Term Results In Patients Younger Than 50 Results of a 30 years experience. L Kerboull, M Hamadouche, M Kerboull. Reliability of THR outcome in young people is still being debated

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Charnley-Kerboull Total Hip Replacement Long Term Results In Patients Younger Than 50 Results of a 30 years experien

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  1. Charnley-Kerboull Total Hip Replacement Long Term Results In Patients Younger Than 50 Results of a 30 years experience L Kerboull, M Hamadouche, M Kerboull.

  2. Reliability of THR outcome in young people is still being debated The cemented metal/PE Kerboull system is now old and someone could think that it is no more indicated for young patients in the third millenium ? Results published in CORR Jan 2004 Long term results in patients under 50

  3. 287 THR performed from 1975 to 1990 Randomly sorted from a cohort of 2804 patients Senior and junior surgeons 222 patients, 144 females and 78 males Mean age : 40,1 y ( ± 8 y ; 15,5 - 50 y). Mean weight : 63 kg (± 18,2 kg ; 37 – 116 kg) The series 172 115

  4. The series : preoperative diagnosis Previous surgery : 123 hips

  5. Transtrochanteric approach Charnley-Kerboull standard implants Cup all poly CMW type 1, mixed in air Distal plug Acetabular reconstruction in 92 hips Operative Technique

  6. Operative Technique : femoral implant Polished 166 Matt 121

  7. Merle d’Aubigné and Postel clinical scoring system Cup : Charnley and Delee classification Stem : Gruen and Amstutz classification Linear Wear : Chevrot and Kerboull M Cystic osteolysis Heterotopic ossifications Statistical analysis Methods

  8. Type of Loosening Socket Femoral Stem Methods : Modified Harris classification for radiological loosening Definite loosening Migration ≥ 3 mm and/or 3° Complete radiolucent line ≥ 2 mm Subsidence ≥ 3 mm Cement mantle fracture Complete radiolucent line ≥ 2 mm Radiolucent line in Zone I ≥ 2 mm Probable loosening Complete radiolucent line < 2 mm Complete radiolucent line < 2 mm Potential loosening Radiolucent line in 2 zones Radiolucent line in 2 zones

  9. Mean follow-up : 14,5 years (± 5.1, 6m to 25 y) 52 hips had a follow-up greater than 20 years

  10. 3 non unions of the trochanter 1%, 1 reoperated 2 Deep infections, 1 acute treated by articular debridment and 1 chronic revised. 3 dislocations, 1 revised 1% 1 hematoma reoperated 3 heterotopic ossification grade 4, 1 reoperated 3 palsies of the peroneal nerve Complications

  11. Clinical results : PMA score postop preop Mean : 9,6 Mean : 17,4 83% of the hips rated excellent to very good

  12. Radiological results : Cup loosening Wear > 0,1 mm/y

  13. Radiological results : cup wear Mean femoral head penetration : 1,3 mm ± 1,5 mm (0 – 8 mm) 0,1mm/y 196 hips 8 ans 91 hips 0.02 mm/y versus 0.28 mm/y P < 0.0001

  14. Wear related factors

  15. Normal versus abnormal wear 1979 : 0,095 mm/an 1980 : 0,158 mm/an Intrinsic properties of PE was the main related factor These changes were due to manufacturing process variations

  16. PE Quality is the main factor Bilateral cases 17 y 18 y

  17. Radiological results : Stem loosening osteolysis 10 aseptic, 1 septic, 1 after a periprosthetic fracture

  18. Radiological loosening : stem Matt vs Polished : p = 0,0001

  19. Matt or polished surface ? Square or rounded cross section ?

  20. Mechanical basis Fact: - Bone, cement and stem form a composite - All mentioned materials have different E-Moduli Cortex: 12 - 18 Gpa PMMA: 1.8 Gpa WHN Stainless Steel 250 Gpa - All material deform differently under load this leads to micro motions

  21. Why the polished stem became matt ? • Initiation of stem loosening: • debonding of the cement to prosthesis interface • Improvement of the bond through a matt surface

  22. With a Matt surface No relative movement between stem and cement possible Micromotions result in localy debonded areas at the bone cement interface which create an abrasive medium that induce osteolisys But ……… Stem PMMA Bone

  23. Stem PMMA Bone While a polished surface Allowes micro movements in the stem to cement viscoelastic interface that protect the bone cement interface

  24. Subsidence: Unlike other stems the CMK is not designed to subside and does not subside. « The French paradox »: Langlais, Ling, Kerboull, Sedel. JBJS Br, 2003. Why ?? - We choose the stem which best fills the medullary canal there is no space for the stem to subside. - The collar decreases the distal force applied to ciment plug - The stem does not get loose due to the cohesion forces acting on the two polished (cement/stem) surfaces. Does a polished cimented stem always subside ?

  25. Round or Rectangular cross section ? Stems are prone to relative rotation when torque forces are applied • Rounder cross section • Prevents hook stresses at the angle • But Increased shear stresses at the interface • Rectangular cross section • Might induce hook stresses • Applies compressive stresses on the cement

  26. Round vs Rectangular a M2 F1a M1 M1 F1b b shear stress compressive stress

  27. The cross section is very delicate: Too round results in problems Too edgy might result in problems (increased hoop stresses) Look for a compromise Almost rectangular with smooth angles cross section design ?

  28. Ra 0.9 m (35  inch) MK 2 : 4 % at 15 Y. Ra 1.7 m (67  inch) CMK 3 : 21 % at 10 Y. Matt surface What was the most deleterious changeMatt surface or rounded cross section

  29. Loosening or wear : 22 7 loosened stems 10 loosened cups 5 worn cups Other : 3 1 septic 1 recurrent dislocation 1 femoral fracture Revisions : 25

  30. Survival rate : revision 1 20 years 85,4% 95% sup : 92,4 % 95% inf : 78,4 % ,8 Suvival rate % ,6 ,4 ,2 0 0 5 10 15 20 25 30 Follow-up years

  31. Survival rate : cup loosening age NS

  32. Survival rate : stem loosening age NS

  33. Survival rate : stem loosening, surface finish 1 ,8 matt ,6 polished ,4 ,2 0 0 5 10 15 20 25 30 P= 0,0001 96,4% 88,5% Suvival rate % Follow-up years

  34. Survival rate : wear dependant Wear <= 0,1 94,8 % Suvival rate % Wear > 0,1 70,6 % P = 0,002 Follow-up years

  35. The Kerboull cemented prosthesis could provide satisfactory and durable results for 20 years in 85 % of patients younger than 50 years. So in our mind it remains a good solution, specially for young patient when anatomic and bony conditions are disturbed. PE wear, when higher than 0.1 mm/y, is the only unsolved problem. PE wear is mainly influenced by PE intrinsic qualities Surface of a cemented stem must be definitely polished to protect cement and bone from excessive stresses. What we learnt at the end of this study

  36. When we change implant, we also experiment new problems and our rate of failure increases compared with our routine technique So we must change for a good reason Bearing surfaces : may be Type of fixation : definitely no , except if imposed by the mechanical properties of the bearing surfaces when using a new implant, If our operative technique is reliable don’t change it, if possible Do we need different implants for young people?

  37. Proven designs are not numerous because a long time is necessary to evaluate a hip prosthesis Before changing try to correct the identified problems Fashion, experimental studies and marketing features are not always our best friends ! Conclusions

  38. Thank you

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