M H Fessy1, S Putman2, A Viste1, R Isida3, N Ramdane4, A Ferreira5, A Leglise6, B Rubens-Duval7, N Bonin8, F Bonnomet9, A Combes10, S Boisgard11, D Mainard9, S Leclercq10, H Migaud2. 1. Clinique du Parc-Lyon, 155 ter, boulevard de Stalingrad, 69006 Lyon, France. 2. Service de chirurgie orthopédique et traumatologique, CHU La Milétrie, 2, rue de La Milétrie, 86000 Poitiers, France. 3. Service de chirurgie orthopédique et traumatologique, CHU La Milétrie, 2, rue de La Milétrie, 86000 Poitiers, France. Electronic address: isida.ronald@gmail.com. 4. Clinique universitaire de chirurgie orthopédique et de traumatologie du sport, hôpital Sud, CHU de Grenoble, 38130 Échirolles, France. 5. Lyon-Ortho-Clinic, 29B, avenue des Sources, 69009 Lyon, France. 6. Service de chirurgie orthopédique et de traumatologie, CHU Hautepierre, hôpital de Hautepierre, hôpitaux universitaires de Strasbourg, 1, avenue Molière, 67098 Strasbourg cedex, France. 7. Centre orthopédique Flemming, 30C, avenue Fleming, 38300 Bourgoin Jallieu, France. 8. Service de chirurgie orthopédique et traumatologique, hôpital Gabriel-Montpied, CHU de Clermont-Ferrand, 63000 Clermont-Ferrand, France. 9. Service de chirurgie orthopédique et traumatologique, hôpitaux universitaires de Nancy, 29, avenue Maréchal-de-Lattre-de-Tassigny, 54000 Nancy, France. 10. CHP Saint-Martin, 18, rue des Roquemonts, 14050 Caen, France. 11. Société française de chirurgie de la hanche et du genou (SFHG), 56, rue Boissonade, 75014 Paris, France.
Abstract
INTRODUCTION: Dislocation after total hip arthroplasty (THA) is a leading reason for surgical revision. The risk factors for dislocation are controversial, particularly those related to the patient and to the surgical procedure itself. The differences in opinion on the impact of these factors stem from the fact they are often evaluated using retrospective studies or in limited patient populations. This led us to carry out a prospective case-control study on a large population to determine: 1) the risk factors for dislocation after THA, 2) the features of these dislocations, and 3) the contribution of patient-related factors and surgery-related factors. HYPOTHESIS: Risk factors for dislocation related to the patient and procedure can be identified using a large case-control study. PATIENTS AND METHODS: A multicenter, prospective case-control study was performed between January 1 and December 31, 2013. Four patients with stable THAs were matched to each patient with a dislocated THA. This led to 566 primary THA cases being included: 128 unstable, 438 stable. The primary matching factors were sex, age, initial diagnosis, surgical approach, implantation date and type of implants (bearing size, standard or dual-mobility cup). RESULTS: The patients with unstable THAs were 67±12 [37-73]years old on average; there were 61 women (48%) and 67 men (52%). Hip osteoarthritis (OA) was the main reason for the THA procedure in 71% (91/128) of the unstable group. The dislocation was posterior in 84 cases and anterior in 44 cases. The dislocation occurred within 3 months of the primary surgery in 48 cases (38%), 3 to 12 months after in 23 cases (18%), 1 to 5years after in 20 cases (16%), 5 to 10years after in 17 cases (13%) and more than 10years later in 20 cases. The dislocation recurred within 6 months of the initial dislocation in 23 of the 128 cases (18%). The risk factors for instability were a high ASA score with an odds ratio (OR) of 1.93 (95% CI: 1.4-2.6), neurological disability (cognitive, motor or psychiatric disorders) with an OR of 3.9 (95% CI: 2.15-7.1), history of spinal disease (lumbar stenosis, spinal fusion, discectomy, scoliosis and injury sequelae) with an OR of 1.89 (95% CI: 1.0-3.6), unrepaired joint capsule (all approaches) with an OR of 4.1 (95% CI: 2.3-7.37), unrepaired joint capsule (posterior approach) with an OR of 6.0 (95% CI: 2.2-15.9), and cup inclination outside Lewinnek's safe zone (30°-50°) with OR of 2.4 (95% CI: 1.4-4.0). DISCUSSION: This large comparative study isolated important patient-related factors for dislocation that surgeons must be aware of. We also found evidence that implanting the cup in 30° to 50° inclination has a major impact on preventing dislocation. LEVEL OF EVIDENCE: Level III; case-control study.
INTRODUCTION: Dislocation after total hip arthroplasty (THA) is a leading reason for surgical revision. The risk factors for dislocation are controversial, particularly those related to the patient and to the surgical procedure itself. The differences in opinion on the impact of these factors stem from the fact they are often evaluated using retrospective studies or in limited patient populations. This led us to carry out a prospective case-control study on a large population to determine: 1) the risk factors for dislocation after THA, 2) the features of these dislocations, and 3) the contribution of patient-related factors and surgery-related factors. HYPOTHESIS: Risk factors for dislocation related to the patient and procedure can be identified using a large case-control study. PATIENTS AND METHODS: A multicenter, prospective case-control study was performed between January 1 and December 31, 2013. Four patients with stable THAs were matched to each patient with a dislocated THA. This led to 566 primary THA cases being included: 128 unstable, 438 stable. The primary matching factors were sex, age, initial diagnosis, surgical approach, implantation date and type of implants (bearing size, standard or dual-mobility cup). RESULTS: The patients with unstable THAs were 67±12 [37-73]years old on average; there were 61 women (48%) and 67 men (52%). Hip osteoarthritis (OA) was the main reason for the THA procedure in 71% (91/128) of the unstable group. The dislocation was posterior in 84 cases and anterior in 44 cases. The dislocation occurred within 3 months of the primary surgery in 48 cases (38%), 3 to 12 months after in 23 cases (18%), 1 to 5years after in 20 cases (16%), 5 to 10years after in 17 cases (13%) and more than 10years later in 20 cases. The dislocation recurred within 6 months of the initial dislocation in 23 of the 128 cases (18%). The risk factors for instability were a high ASA score with an odds ratio (OR) of 1.93 (95% CI: 1.4-2.6), neurological disability (cognitive, motor or psychiatric disorders) with an OR of 3.9 (95% CI: 2.15-7.1), history of spinal disease (lumbar stenosis, spinal fusion, discectomy, scoliosis and injury sequelae) with an OR of 1.89 (95% CI: 1.0-3.6), unrepaired joint capsule (all approaches) with an OR of 4.1 (95% CI: 2.3-7.37), unrepaired joint capsule (posterior approach) with an OR of 6.0 (95% CI: 2.2-15.9), and cup inclination outside Lewinnek's safe zone (30°-50°) with OR of 2.4 (95% CI: 1.4-4.0). DISCUSSION: This large comparative study isolated important patient-related factors for dislocation that surgeons must be aware of. We also found evidence that implanting the cup in 30° to 50° inclination has a major impact on preventing dislocation. LEVEL OF EVIDENCE: Level III; case-control study.
Authors: Timothy S Brown; Richard J McLaughlin; Daniel J Berry; David G Lewallen; Robert T Trousdale; Rafael J Sierra Journal: Clin Orthop Relat Res Date: 2019-02 Impact factor: 4.176
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