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

BMC Musculoskeletal Disorders

Research Article

Martin Haimerl¹  Sabine Gneiting¹  Lars Dohmen¹  Patrick Sussmann²  Joachim Grifka²  Markus Weber²  Tobias Renkawitz²  Philipp Lechler²  Michael Woerner²  Hans-Robert Springorum²  Ernst Sendtner² 

[1] Brainlab AG, R&D Surgery, Feldkirchen, Germany;Department of Orthopaedic Surgery, Regensburg University Medical Center, Regensburg, Germany;

关键词: Mechanical Axis;    Shaft Axis;    Posterior Condyle Axis;    Combine Anteversion;    Postoperative Compute Tomography Scan;   

DOI  :  10.1186/1471-2474-13-65

 received in 2011-09-02, accepted in 2012-05-04,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundThere 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.MethodsThe 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.ResultsThe mean postoperative FT on CT scans was 5.7° ± 1.8°. 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° change in FT, the impingement-free cup position differed by 4° for inclination when the same antetorsion was used.ConclusionsA 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.

【 授权许可】

CC BY   
© Renkawitz et al.; licensee BioMed Central Ltd. 2012