Alejandro Hernández1,2, Kushal Lakhani1,2, Jorge H Núñez1,2, Iñaki Mimendia1,2, Aleix Pons1,2, Víctor Barro1,2. 1. Hip Unit, Department of Orthopedic Surgery, University Hospital of Vall d'Hebron, Universitat Autónoma de Barcelona, Passeig de la Vall d'Hebron, 119-129, 08035, Barcelona, Spain. 2. Universitat Autónoma de Barcelona, Passeig de la Vall d'Hebron, 119-129, 08035, Barcelona, Spain.
Abstract
INTRODUCTION: Dislocation is one of the most common complications after primary total hip arthroplasty (THA). Combined anteversion (CA) is currently considered one of the most important measures of stability for THA. Thus, the aim of this study is to determine the association between a correct CA after THA and hip prosthesis dislocation, and to analyze the reliability of the Lewinnek safe zone parameters. MATERIAL AND METHODS: This is a non-interventional retrospective study, carried out at a tertiary hospital in Spain. 2489 primary THA in 2147 patients between January 2008 and December 2014 were identified. Clinical, biological and radiographic data, including cup inclination and cup and femoral anteversion, were analyzed of all patients who developed a hip prosthesis dislocation. RESULTS: Thirty-four patients met the eligibility criteria to be analyzed. In 73.5% (25/34) of cases, acetabular anteversion (AV) was correct, with a mean AV of 15.1° ± 9.4°. Femoral anteversion (FA) was considered correct only in 38.2% (13/34) of the dislocated THA, with a mean FA of 8.4° ± 17.2°. Sixteen of these 34 patients (47.0%) presented a correct CA, with a mean CA of 24.2° ± 21.0°. Nineteen hips (55.8%) were within the Lewinnek safe zone. Moreover, eleven patients (32.3%) developed a dislocation even though components were within the Lewinnek safe zone and presented a correct CA. CONCLUSION: Our findings suggest that even when the THA components are positioned within a correct CA and in the Lewinnek safe zone, hip prosthesis dislocations can occur in a not inconsiderable percentage of the cases. Thus, further radiological and clinical analysis should be done to identify potential reasons for hip prosthesis dislocation.
INTRODUCTION: Dislocation is one of the most common complications after primary total hip arthroplasty (THA). Combined anteversion (CA) is currently considered one of the most important measures of stability for THA. Thus, the aim of this study is to determine the association between a correct CA after THA and hip prosthesis dislocation, and to analyze the reliability of the Lewinnek safe zone parameters. MATERIAL AND METHODS: This is a non-interventional retrospective study, carried out at a tertiary hospital in Spain. 2489 primary THA in 2147 patients between January 2008 and December 2014 were identified. Clinical, biological and radiographic data, including cup inclination and cup and femoral anteversion, were analyzed of all patients who developed a hip prosthesis dislocation. RESULTS: Thirty-four patients met the eligibility criteria to be analyzed. In 73.5% (25/34) of cases, acetabular anteversion (AV) was correct, with a mean AV of 15.1° ± 9.4°. Femoral anteversion (FA) was considered correct only in 38.2% (13/34) of the dislocated THA, with a mean FA of 8.4° ± 17.2°. Sixteen of these 34 patients (47.0%) presented a correct CA, with a mean CA of 24.2° ± 21.0°. Nineteen hips (55.8%) were within the Lewinnek safe zone. Moreover, eleven patients (32.3%) developed a dislocation even though components were within the Lewinnek safe zone and presented a correct CA. CONCLUSION: Our findings suggest that even when the THA components are positioned within a correct CA and in the Lewinnek safe zone, hip prosthesis dislocations can occur in a not inconsiderable percentage of the cases. Thus, further radiological and clinical analysis should be done to identify potential reasons for hip prosthesis dislocation.
Authors: Markus Weber; Michael Woerner; Benjamin Craiovan; Florian Voellner; Michael Worlicek; Hans-Robert Springorum; Joachim Grifka; Tobias Renkawitz Journal: Int Orthop Date: 2016-04-22 Impact factor: 3.075