Gusztáv Fekete1,2, Dong Sun2, Yaodong Gu2, Patric Daniel Neis3, Ney Francisco Ferreira3, Bernardo Innocenti4, Béla M Csizmadia5. 1. Savaria Institute of Technology, Eötvös Loránd University, Szombathely, Hungary. 2. Research Academy of Grand Health, Ningbo University, Ningbo, China. 3. Laboratory of Tribology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. 4. BEAMS Department, Université Libre de Bruxelles, Brussels, Belgium. 5. Institute of Mechanics and Machinery, Szent István University, Gödöllő, Hungary.
Abstract
INTRODUCTION: Due to the more resilient biomaterials, problems related to wear in total knee replacements (TKRs) have decreased but not disappeared. In the design-related factors, wear is still the second most important mechanical factor that limits the lifetime of TKRs and it is also highly influenced by the local kinematics of the knee. During wear experiments, constant load and slide-roll ratio is frequently applied in tribo-tests beside other important parameters. Nevertheless, numerous studies demonstrated that constant slide-roll ratio is not accurate approach if TKR wear is modelled, while instead of a constant load, a flexion-angle dependent tibiofemoral force should be involved into the wear model to obtain realistic results. METHODS: A new analytical wear model, based upon Archard's law, is introduced, which can determine the effect of the tibiofemoral force and the varying slide-roll on wear between the tibiofemoral connection under standard and non-standard squat movement. RESULTS: The calculated total wear with constant slide-roll during standard squat was 5.5 times higher compared to the reference value, while if total wear includes varying slide-roll during standard squat, the calculated wear was approximately 6.25 times higher. With regard to non-standard squat, total wear with constant slide-roll during standard squat was 4.16 times higher than the reference value. If total wear included varying slide-roll, the calculated wear was approximately 4.75 times higher. CONCLUSIONS: It was demonstrated that the augmented force parameter solely caused 65% higher wear volume while the slide-roll ratio itself increased wear volume by 15% higher compared to the reference value. These results state that the force component has the major effect on wear propagation while non-standard squat should be proposed for TKR patients as rehabilitation exercise.
INTRODUCTION: Due to the more resilient biomaterials, problems related to wear in total knee replacements (TKRs) have decreased but not disappeared. In the design-related factors, wear is still the second most important mechanical factor that limits the lifetime of TKRs and it is also highly influenced by the local kinematics of the knee. During wear experiments, constant load and slide-roll ratio is frequently applied in tribo-tests beside other important parameters. Nevertheless, numerous studies demonstrated that constant slide-roll ratio is not accurate approach if TKR wear is modelled, while instead of a constant load, a flexion-angle dependent tibiofemoral force should be involved into the wear model to obtain realistic results. METHODS: A new analytical wear model, based upon Archard's law, is introduced, which can determine the effect of the tibiofemoral force and the varying slide-roll on wear between the tibiofemoral connection under standard and non-standard squat movement. RESULTS: The calculated total wear with constant slide-roll during standard squat was 5.5 times higher compared to the reference value, while if total wear includes varying slide-roll during standard squat, the calculated wear was approximately 6.25 times higher. With regard to non-standard squat, total wear with constant slide-roll during standard squat was 4.16 times higher than the reference value. If total wear included varying slide-roll, the calculated wear was approximately 4.75 times higher. CONCLUSIONS: It was demonstrated that the augmented force parameter solely caused 65% higher wear volume while the slide-roll ratio itself increased wear volume by 15% higher compared to the reference value. These results state that the force component has the major effect on wear propagation while non-standard squat should be proposed for TKR patients as rehabilitation exercise.
Authors: H Nägerl; K H Frosch; M M Wachowski; C Dumont; C Abicht; P Adam; D Kubein-Meesenburg Journal: Acta Bioeng Biomech Date: 2008 Impact factor: 1.073
Authors: Anthony P Sanders; Carly A Lockard; Joel N Weisenburger; Hani Haider; Bart Raeymaekers Journal: J Biomed Mater Res B Appl Biomater Date: 2015-02-10 Impact factor: 3.368