The association between Femoral Tilt and impingement-free range-of-motion in total hip arthroplasty

Renkawitz, Tobias and Haimerl, Martin and Dohmen, Lars and Gneiting, Sabine and Lechler, Philipp and Woerner, Michael and Springorum, Hans-Robert and Weber, Markus and Sussmann, Patrick and Sendtner, Ernst and Grifka, Joachim (2012) The association between Femoral Tilt and impingement-free range-of-motion in total hip arthroplasty. BMC MUSCULOSKELETAL DISORDERS, 13: 65. ISSN 1471-2474,

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Abstract

Background: There is a complex interaction among acetabular component position and antetorsion of the femoral stem in determining the maximum, impingement-free prosthetic range-of-motion (ROM) in total hip arthroplasty (THA). By insertion into the femoral canal, stems of any geometry follow the natural anterior bow of the proximal femur, creating a sagittal Femoral Tilt (FT). We sought to study the incidence of FT as measured on postoperative computed tomography scans and its influence on impingement-free ROM in THA. Methods: The incidence of the postoperative FT was evaluated on 40 computed tomography scans after cementless THA. With the help of a three-dimensional computer model of the hip, we then systematically analyzed the effects of FT on femoral antetorsion and its influence on calculations for a ROM maximized and impingement-free compliant stem/cup orientation. Results: The mean postoperative FT on CT scans was 5.7 degrees +/- 1.8 degrees. In all tests, FT significantly influenced the antetorsion values. Re-calculating the compliant component positions according to the concept of combined anteversion with and without the influence of FT revealed that the zone of compliance could differ by more than 200%. For a 7 degrees change in FT, the impingement-free cup position differed by 4 degrees for inclination when the same antetorsion was used. Conclusions: A range-of-motion optimized cup position in THA cannot be calculated based on antetorsion values alone. The FT has a significant impact on recommended cup positions within the concept of "femur first" or "combined anteversion". Ignoring FT may pose an increased risk of impingement as well as dislocation.

Item Type: Article
Uncontrolled Keywords: CUP; REPLACEMENT; ORIENTATION; DISLOCATION; COMPONENTS;
Subjects: 600 Technology > 610 Medical sciences Medicine
Divisions: Medicine > Lehrstuhl für Chirurgie
Depositing User: Dr. Gernot Deinzer
Date Deposited: 14 May 2020 05:34
Last Modified: 14 May 2020 05:34
URI: https://pred.uni-regensburg.de/id/eprint/18749

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