Periprosthetic femoral fracture after total hip replacement Incidence, risk factors and treatment Georgios Chatziagorou Department of Orthopaedics, Institute of Clinical Sciences Sahlgrenska Academy, University of Gothenburg Gothenburg 2020 Periprosthetic femoral fracture after total hip replacement: incidence, risk factors and treatment. © Georgios Chatziagorou 2020 [email protected] The copyright of the contents of this thesis belongs to Georgios Chatziagorou. The published articles are reproduced with permission from the respective journals. Cover illustration by Pontus Andersson Layout by Nikolaos Vryniotis Printed in Borås, Sweden 2020 Printed by Stema Specialtryck AB ISBN 978-91-7833-778-1 (PRINT) ISBN 978-91-7833-997-8 (PDF) http://hdl.handle.net/2077/62689 «Μέτρον ἄριστον» “Lagom är bäst” (Moderation is best) Table of contents ABSTRACT .......................................................................................................... 9 SAMMANFATTNING (SUMMARY IN SWEDISH) .................................. 13 LIST OF PAPERS ............................................................................................... 17 ABBREVIATIONS .............................................................................................. 19 1. INTRODUCTION ............................................................................................ 23 2. BACKGROUND ............................................................................................. 25 2.1 TYPES OF TOTAL HIP REPLACEMENT.......................................................... 25 2.2 DESIGN OF CEMENTED STEMS ................................................................... 28 2.3 DESIGN OF UNCEMENTED STEMS ............................................................... 29 2.4 THE SWEDISH HIP ARTHROPLASTY REGISTER (SHAR) ........................... 30 2.5 THE NATIONAL PATIENT REGISTER (NPR) .............................................. 31 2.6 THE SWEDISH FRACTURE REGISTER (SFR) ............................................. 32 2.7 THE REPORTING OF PPFFS IN REGISTERS ABROAD ............................... 32 2.8 CLASSIFICATION OF PERIPROSTHETIC FEMORAL FRACTURES ................... 33 2.8.1 Previous classification systems ......................................... 33 2.8.2 The Vancouver classification system ............................. 35 2.8.3 Modifications of the Vancouver classification system........................................................................ 37 2.9 THE INTERPROSTHETIC FEMORAL FRACTURE AND ITS CLASSIFICATION .......................................................................................... 39 2.10 INTRAOPERATIVE AND POSTOPERATIVE FRACTURES ............................. 40 2.11 RISK FACTORS FOR PPFF ...................................................................... 40 2.11.1 Technically related risk factors ......................................... 41 2.11.2 Patient-related risk factors ................................................ 42 2.12 INCIDENCE ............................................................................................... 44 2.12.1 Incidence of various fracture types ................................ 45 2.13 TREATMENT ............................................................................................. 46 2.13.1 General considerations ........................................................ 46 2.13.2 Cerclage ................................................................................... 47 2.13.3 Plate fixation .......................................................................... 48 2.13.4 Vancouver type A ................................................................ 50 2.13.5 Vancouver type B1 ............................................................... 51 2.13.6 Vancouver types B2 and B3............................................. 52 2.13.7 Vancouver type C ................................................................. 55 2.13.8 Interprosthetic fractures (IPFF) ...................................... 57 2.14 OUTCOME OF PPFFS AND MEASUREMENT TOOLS ................................ 58 2.15 OUTCOME OF PPFFS AND RISK FACTORS ............................................. 59 2.16 MORTALITY AND RISK FACTORS ............................................................. 60 2.17 FINANCIAL BURDEN ................................................................................. 61 2.18 THE USUAL CASE WITH A PERIPROSTHETIC FRACTURE ........................... 61 3. AIMS .................................................................................................................. 63 STUDY I ............................................................................................................ 63 STUDY II........................................................................................................... 63 STUDY III ......................................................................................................... 63 STUDY IV ......................................................................................................... 63 4. PATIENTS AND METHODS ...................................................................... 65 4.1 STUDY DESIGN ........................................................................................... 65 4.2 DATA SOURCES......................................................................................... 65 4.3 DATA LINKAGE ......................................................................................... 65 4.4 CLASSIFICATION OF PERIPROSTHETIC FRACTURES IN THIS THESIS ........... 67 4.5 DISTINGUISHING INTRA- AND POSTOPERATIVE FRACTURES ..................... 68 4.6 PATIENTS .................................................................................................. 69 4.6.1 Exclusion criteria .................................................................... 69 4.6.2 Study I ........................................................................................ 69 4.6.3 Study II ..................................................................................... 70 4.6.4 Study III .................................................................................... 70 4.6.5 Study IV .................................................................................... 70 4.7 SUB-ANALYSES IN STUDIES II-IV ............................................................ 71 4.7.1 Study II ........................................................................................ 71 4.7.2 Study III ...................................................................................... 71 4.7.3 Study IV ..................................................................................... 71 4.8 OUTCOME MEASUREMENTS ....................................................................... 72 4.9 STATISTICAL METHODS ............................................................................. 72 4.10 PRIMARY OUTCOME MEASUREMENT AND CENSORING IN COX REGRESSION ANALYSES .................................................... 72 4.11 ETHICS ..................................................................................................... 73 5. RESULTS ......................................................................................................... 75 5.1 VALIDATION OF THE CLASSIFICATION PROCESS ........................................ 75 5.2 REGISTRATION OF PERIPROSTHETIC FRACTURES IN THE SHAR .............. 75 5.3 INCIDENCE (STUDY I) .............................................................................. 77 5.4 AGE .......................................................................................................... 78 5.5 GENDER .................................................................................................... 79 5.6 FRACTURE TYPES ...................................................................................... 79 5.7 DIAGNOSIS AT PRIMARY THR .................................................................. 80 5.8 TIME TO PPFF ........................................................................................ 80 5.9 FIXATION AND DESIGN OF THE PRIMARY STEM ......................................... 81 5.10 RISK FACTORS FOR PPFF (STUDY II) ................................................. 81 5.11 TREATMENT OF VANCOUVER TYPE B FRACTURES (STUDY III) ............. 82 5.12 TREATMENT OF VANCOUVER TYPE C FRACTURES (STUDY IV) ............ 82 5.13 OUTCOME IN VANCOUVER TYPE B FRACTURES (STUDY III) ................ 82 5.14 OUTCOME IN VANCOUVER TYPE C FRACTURES (STUDY IV) ............... 86 5.15 RISK FACTORS FOR RE-REOPERATION AFTER A PPFF ........................ 87 5.16 TIME TO TREATMENT, MECHANISM OF INJURY, WEIGHT-BEARING, DISCHARGE AND MORTALITY............................................... 87 6. DISCUSSION .................................................................................................. 91 6.1 THE MATERIAL IN THIS THESIS ................................................................... 91 6.2 VALIDATION OF THE CLASSIFICATION PROCESS AND THE VANCOUVER CLASSIFICATION SYSTEM ...................................................... 91 6.3 VALIDATION OF THE SHAR DATABASE AND THE IMPACT OF DATA LINKING .......................................................................... 93 6.4 THE INCIDENCE OF PERIPROSTHETIC FEMORAL FRACTURES ..................... 94 6.5 PATIENT CHARACTERISTICS ...................................................................... 95 6.6 RISK FACTORS FOR PPFF AROUND A CEMENTED PRIMARY HIP STEM (STUDY II) ..................................................