1. THA after Chiari osteotomy: Intraoperative complications and behaviour of cup fixation in 24 cases Migaud H., Beniluz J., Gougeon F., Pinoit Y., Besson A., Duquennoy A. Department of Orthopaedic Surgery, University Hospital of Lille, France.

2. Introduction : Conservative surgery to prevent or stabilize arthrosis without worsening the result of a subsequent THR :Conservative surgery to prevent or stabilize arthrosis without worsening the result of a subsequent THR : –Problems related to THR after proximal osteotomy of the femur –Few papers related to the THR after pelvic osteotomies PETERS CJ : J Arthroplasty, 2001 13 hips : worse result THR after failed TIO. Fw-up 36 m. HASHEMI-N A : J Arthroplasty, 2002 28 hips : THR after Chiari results = to primary THR, but less pelvic bone grafting Fw-up 60 m. PARVIZI J : CORR, 2004 41hips : THR after PAO caution to acetabular retroversion (23/41) Fw-up 6,9 years

3. Introduction : Purpose of the study Modifications of the acetabulum related to the Chiari osteotomyModifications of the acetabulum related to the Chiari osteotomy –Medial displacement –Enlargement –Vascular and bone support Concerns aboutConcerns about 1) long term fixation of the cup 2) Functional result 3) Intraoperative complications

4. Patients and Methods 204 Chiari osteotomies (1975-2000)  29 hips conversed to THR204 Chiari osteotomies (1975-2000)  29 hips conversed to THR 24 THR with a follow-up > 5 years were assessed retrospectively24 THR with a follow-up > 5 years were assessed retrospectively 23 patients (20 F, 3 M)23 patients (20 F, 3 M) Mean age at the time of conversion = 50 y. (range, 36-63)Mean age at the time of conversion = 50 y. (range, 36-63)

5. Patients and Methods (n = 24) Chiari were “dome shaped” and performed through a Smith PetersenChiari were “dome shaped” and performed through a Smith Petersen Fixed with lag screwsFixed with lag screws Indication for Chiari :Indication for Chiari : –Dysplasia (15/24 CE < 5°) –Arthrosis (20/24 had joint space narrowing)

6. Patients and Methods (n = 24) Conversion after a mean follow- up of 8 y. (range 1-24 y.)Conversion after a mean follow- up of 8 y. (range 1-24 y.) All THR through a Postero- Lateral approachAll THR through a Postero- Lateral approach No patient lost for follow-upNo patient lost for follow-up Mean THR follow-up = 10 +/- 3 y. (range, 6-15)Mean THR follow-up = 10 +/- 3 y. (range, 6-15)

7. Components (n = 24) CementedCementless Stems195 Muller/KerboullCLS/Alloclassic Cups3 Full Poly 21 Harris/Allofit

8. Functional Results (n = 24, Fw-up = 10y.) Favorable functional resultsFavorable functional results All the walking scores at follow-up > 5 pointsAll the walking scores at follow-up > 5 points Merle d’Aubigné Hip rating

9. Functional Results (n = 24) No postoperative dislocation despite medial displacement by Chiari osteotomyNo postoperative dislocation despite medial displacement by Chiari osteotomy Post-operative LimpPost-operative Limp Number of Hips with a Trendelenburg

10. Results: Intraoperative complications No neurovascular injuryNo neurovascular injury Screw removal necessary in 9 casesScrew removal necessary in 9 cases –To avoid contact between screws used for Chiari and cup fixation or to ease bone preparation –Difficult in 2 cases (the distal part of the screw was broken and left in place)

11. Results: Cup fixation and bone coverage Three cases of lack in bone coverage > 20% of the cup (all posterior and superior)Three cases of lack in bone coverage > 20% of the cup (all posterior and superior) –1 treated by deepening –1 treated by few bone chips –1 treated by autograft One additional case of autograft to correctly locate the hip center in a dislocated hipOne additional case of autograft to correctly locate the hip center in a dislocated hip

12. Results: Cup fixation and Impingement Anterior impingement with the Major trochanter in 2 cases (excessive anterior coverage)Anterior impingement with the Major trochanter in 2 cases (excessive anterior coverage) Bone resection required on the pelvic bone in 2 casesBone resection required on the pelvic bone in 2 cases

13. Results: Cup orientation Mean frontal angle = 43° +/-9° [20° to 58°]Mean frontal angle = 43° +/-9° [20° to 58°] 3 cups had inclination < 35° and 2 over 55°3 cups had inclination < 35° and 2 over 55° 4 hips had M-M bearings (in 28 mm) without impingement4 hips had M-M bearings (in 28 mm) without impingement

14. Results: Cup Fixation None of the cemented cups and 18/21 cementless cups = free of osteolysis, no radiolucencies, no migrationNone of the cemented cups and 18/21 cementless cups = free of osteolysis, no radiolucencies, no migration 3 of the cementless cups had radiolucencies (2 of them had progressive lucencies and severe osteolysis  reoperation)3 of the cementless cups had radiolucencies (2 of them had progressive lucencies and severe osteolysis  reoperation) 10 y. #1

15. Results: Reoperation #1 #1 #1 4y. Post Only 2 patients had revision surgery (osteolysis, wear)Only 2 patients had revision surgery (osteolysis, wear) No revision was related to the prior osteotomy :No revision was related to the prior osteotomy : #1 (@ 5y.) osteolysis + cup loosening (osteolysis) =#1 (@ 5y.) osteolysis + cup loosening (osteolysis) = –Intra-articular migration of metallic debris from the coating (Fibermesh) –Bone grafting + cup revision

16. Results: Reoperation #2 (@15y.) Osteolysis + loosening cup + femur =#2 (@15y.) Osteolysis + loosening cup + femur = –Severe polyethylene wear –Poor fixation of the insert in the metallic shell –Overweight (BMI = 31) –Pelvic grafting with cup and femoral revision (cementless locked stem) #2 #2 Post-op #2 1y. Post

17. Conclusions (1) Conversion of a Chiari to THR = simple procedureConversion of a Chiari to THR = simple procedure Low rate of acetabular augmentation (bone grafting) despite severe dysplasia before the Chiari)Low rate of acetabular augmentation (bone grafting) despite severe dysplasia before the Chiari) Attention should be paid to bone-to-bone impingement if excessive bone coverageAttention should be paid to bone-to-bone impingement if excessive bone coverage

18. Conclusions (2) Chiari osteotomy :Chiari osteotomy : 1) does not modifiy rehabilitation program versus with primary THR 2) does not worsen cup fixation = only 2 revisions but none related to the prior osteotomy 3) gives the opportunity to insert larger cups (resistance to wear) Primary THRTHR post Chiari

19. Thank you for your attention