Nils Wirries1,2, Marcus Örgel3, Michael Schwarze4, Stefan Budde5, Henning Windhagen5, Michael Skutek5. 1. Department of Orthopaedic Surgery at Diakovere Annastift, Hannover Medical School, Hannover, Germany. Nils.Wirries@ocm-muenchen.de. 2. Orthopädische Chirurgie München, Steinerstraße 6, 81369, Munich, Germany. Nils.Wirries@ocm-muenchen.de. 3. Trauma Department, Hannover Medical School, Hannover, Germany. 4. Laboratory for Biomechanics and Biomaterials, Hannover Medical School, Hannover, Germany. 5. Department of Orthopaedic Surgery at Diakovere Annastift, Hannover Medical School, Hannover, Germany.
Abstract
INTRODUCTION: Using cementless stems in total hip arthroplasty (THA) has revealed variable results. The risk for early aseptic loosening has been associated to certain surgical approaches and implant designs. This study determines misalignment of collared/collarless stems and the rate of subsidence using the anterolateral approach (ALA) compared to implantations via the direct lateral approach (DLA). MATERIALS AND METHODS: One hundred consecutive patients underwent primary unilateral THA using the minimal invasive ALA in the lateral decubitus position and were compared to another cohort of 100 patients, treated trough the DLA. Clinical results were noted preoperatively and after 1 year using the WOMAC score. The radiographic evaluation included the stem alignment and subsidence. RESULTS: Overall, all patients improved in WOMAC from 48.9 points (± 11.4; 21.0-82.0) to 3.1 (± 3.2; 0.0-22.0) (p < 0.001). For DLA and ALA, the stem was placed on average 2.5° in varus to the femoral axis. The mean alignment was about 0.5° more valgus for collarless stems. The mean subsidence in the DLA group was about 0.3 mm higher compared to the ALA group. With collarless implants, the subsidence was about 1.0 mm higher compared to collared implants (p < 0.05), especially in patients with Dorr type B femurs. CONCLUSIONS: Changing from the DLA to the minimal invasive ALA did not significantly affect the implant position. Misalignment and a potential risk for early aseptic loosening could not be seen. The use of a collared cementless stem seems safe and is likely to prevent a relevant subsidence, even more so in Dorr type B femurs. LEVEL OF EVIDENCE: III.
INTRODUCTION: Using cementless stems in total hip arthroplasty (THA) has revealed variable results. The risk for early aseptic loosening has been associated to certain surgical approaches and implant designs. This study determines misalignment of collared/collarless stems and the rate of subsidence using the anterolateral approach (ALA) compared to implantations via the direct lateral approach (DLA). MATERIALS AND METHODS: One hundred consecutive patients underwent primary unilateral THA using the minimal invasive ALA in the lateral decubitus position and were compared to another cohort of 100 patients, treated trough the DLA. Clinical results were noted preoperatively and after 1 year using the WOMAC score. The radiographic evaluation included the stem alignment and subsidence. RESULTS: Overall, all patients improved in WOMAC from 48.9 points (± 11.4; 21.0-82.0) to 3.1 (± 3.2; 0.0-22.0) (p < 0.001). For DLA and ALA, the stem was placed on average 2.5° in varus to the femoral axis. The mean alignment was about 0.5° more valgus for collarless stems. The mean subsidence in the DLA group was about 0.3 mm higher compared to the ALA group. With collarless implants, the subsidence was about 1.0 mm higher compared to collared implants (p < 0.05), especially in patients with Dorr type B femurs. CONCLUSIONS: Changing from the DLA to the minimal invasive ALA did not significantly affect the implant position. Misalignment and a potential risk for early aseptic loosening could not be seen. The use of a collared cementless stem seems safe and is likely to prevent a relevant subsidence, even more so in Dorr type B femurs. LEVEL OF EVIDENCE: III.
Authors: Loes Janssen; Karolina A P Wijnands; Dennis Janssen; Michiel W H E Janssen; Jan W Morrenhof Journal: Clin Orthop Relat Res Date: 2018-06 Impact factor: 4.176
Authors: Shuichi Eto; Katherine Hwang; James I Huddleston; Derek F Amanatullah; William J Maloney; Stuart B Goodman Journal: J Arthroplasty Date: 2016-10-08 Impact factor: 4.757