Nicola Armillotta1, Edoardo Bori2, Bernardo Innocenti1. 1. BEAMS Department (Bio Electro and Mechanical Systems), Université Libre de Bruxelles, École Polytechnique de Bruxelles, Av. F. Roosevelt, 50 CP165/56, 1050, Brussels, Belgium. 2. BEAMS Department (Bio Electro and Mechanical Systems), Université Libre de Bruxelles, École Polytechnique de Bruxelles, Av. F. Roosevelt, 50 CP165/56, 1050, Brussels, Belgium. edoardo.bori@gmail.com.
Abstract
PURPOSE: Bi-unicompartmental knee arthroplasty is a less invasive treatment than a total one, great advantage for the patient but more difficult for the surgeon because of the lower visibility during surgery; this can therefore lead to eventual small errors in cutting angles during the procedure. The aim of this study is to investigate the effects of these slight angle variations in terms of anterior-posterior slope for the lateral tibial tray. METHODS: The geometries of the bones were acquired and uncemented fixed bearing metal-back UKAs virtually implanted in a finite elements environment. The lateral component was implanted in six different antero-posterior slope configurations (from - 5° to + 5° respect to medial component). Material properties for implant, bones and soft tissues were taken from the literature. A vertical compressive force of 2000 N was applied in full-extended configuration on the femur. Von Mises stress distribution in proximal tibia, load/pressure/contact area repartitions between the medial and lateral compartments was extracted as outputs. RESULTS: Outcomes for 0° and - 3° configurations are acceptable, but the - 2° of slope configuration achieved the best ones in terms of stress on proximal tibia, load repartition, contact pressure distribution and shear component. Drastically different results are found for the ± 5° configurations, presenting a level of unbalancing often associated with weak stability and failure over time. CONCLUSIONS: Slight errors can happen during the surgery: performing the cut aiming to slightly posterior slopes during the surgery helps to minimize the chances of obtaining positive slopes that could lead to an unstable implant.
PURPOSE: Bi-unicompartmental knee arthroplasty is a less invasive treatment than a total one, great advantage for the patient but more difficult for the surgeon because of the lower visibility during surgery; this can therefore lead to eventual small errors in cutting angles during the procedure. The aim of this study is to investigate the effects of these slight angle variations in terms of anterior-posterior slope for the lateral tibial tray. METHODS: The geometries of the bones were acquired and uncemented fixed bearing metal-back UKAs virtually implanted in a finite elements environment. The lateral component was implanted in six different antero-posterior slope configurations (from - 5° to + 5° respect to medial component). Material properties for implant, bones and soft tissues were taken from the literature. A vertical compressive force of 2000 N was applied in full-extended configuration on the femur. Von Mises stress distribution in proximal tibia, load/pressure/contact area repartitions between the medial and lateral compartments was extracted as outputs. RESULTS: Outcomes for 0° and - 3° configurations are acceptable, but the - 2° of slope configuration achieved the best ones in terms of stress on proximal tibia, load repartition, contact pressure distribution and shear component. Drastically different results are found for the ± 5° configurations, presenting a level of unbalancing often associated with weak stability and failure over time. CONCLUSIONS: Slight errors can happen during the surgery: performing the cut aiming to slightly posterior slopes during the surgery helps to minimize the chances of obtaining positive slopes that could lead to an unstable implant.
Authors: Nicholas M Brown; Neil P Sheth; Kenneth Davis; Mike E Berend; Adolph V Lombardi; Keith R Berend; Craig J Della Valle Journal: J Arthroplasty Date: 2012-05-04 Impact factor: 4.757
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Authors: Jeremy F Suggs; Guoan Li; Sang Eun Park; Peter G Sultan; Harry E Rubash; Andrew A Freiberg Journal: J Orthop Res Date: 2006-04 Impact factor: 3.494
Authors: Philip Winnock de Grave; Justine Barbier; Thomas Luyckx; Alexander Ryckaert; Paul Gunst; Luc Van den Daelen Journal: J Arthroplasty Date: 2018-04-24 Impact factor: 4.757