Fonseca Ulloa CA 1, Seeger A 2,Ishaque BA 1,2, Ahmed GA 1,2 , Jahnke 1, Rickert M 1,2.
Med Eng Phys. 2020 Dec;86:122-127. doi: 10.1016/j.medengphy.2020.11.001 . Epub 2020 Nov 11. PMID: 33261725
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392, Giessen, Germany.
- Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstraße 33, 35392, Giessen, Germany.
The continuous improvement of minimally invasive hip endoprostheses surgery comes with a change in geometries of surgery instruments like the broach handles. Consequently, depending on the handles‘ curvature this results in a deviation between handle and femoral axis. Therefore, this study aimed to prove the influence of different handles‘ curvatures on the preparation of implant site and acting forces and moments in this process. Five femoral models attached to different handles (double-curved, single-curved, straight) were locked in a drop-weight device with standardize implantation forces and moments and five strokes were measured for each possible combination. Distribution of force and moment components was dependent on the handle’s curvature, where the lowest variation from the standard force values was by the straight one (av:15.2% ± 0.5%) and the strongest discrepancies were exhibit by the double-curved one (av:54.3% ± 0.1%.). Moment values have also shown this trend with the lowest variation (12.4%-23.3%) by the straight one and the highest discrepancies (56,6%-90.9%) by the double-curved one. Results show that unguided axial impact introduces unwanted transverse forces and moments into the femur. Therefore, broach handles should be modified accordingly so that minimally invasive surgery remains feasible but unwanted forces or moments can still be compensated.
Keywords: Biomechanics; Broach handles; Endoprosthesis; Minimally-invasive-surgery; THA.