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Background: Experimental knee implant wear testing according to ISO 14243 is a standard procedure, but it inherently possesses limitations for preclinical evaluations due to extended testing periods and costly infrastructure. In an effort to overcome these limitations, we hereby develop and experimentally validate a finite-element (FE)-based algorithm, including a novel cross-shear and contact pressure dependent wear and creep model, and apply it towards understanding the sensitivity of wear outcomes to the applied boundary conditions., Methods: Specifically, we investigated the application of in vivo data for level walking from the publicly available "Stan" data set, which contains single representative tibiofemoral loads and kinematics derived from in vivo measurements of six subjects, and compared wear outcomes against those obtained using the ISO standard boundary conditions. To provide validation of the numerical models, this comparison was reproduced experimentally on a six-station knee wear simulator over 5 million cycles, testing the same implant Stan's data was obtained from., Results: Experimental implementation of Stan's boundary conditions in displacement control resulted in approximately three times higher wear rates (4.4 vs. 1.6 mm 3 per million cycles) and a more anterior wear pattern compared to the ISO standard in force control. While a force-controlled ISO FE model was unable to reproduce the bench test kinematics, and thus wear rate, due to a necessarily simplified representation of the simulator machine, similar but displacement-controlled FE models accurately predicted the laboratory wear tests for both ISO and Stan boundary conditions. The credibility of the in silico wear and creep model was further established per the ASME V&V-40 standard., Conclusions: The FE wear model is suitable for supporting future patient-specific models and development of novel implant designs. Incorporating the Stan data set alongside ISO boundary conditions emphasized the value of using measured kinematics in displacement control for reliably replicating in vivo joint mechanics in wear simulation. Future work should focus on expanding the range of daily activities simulated and addressing model sensitivity to contact mechanics to further enhance predictive accuracy., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: MJD, SHHN, BW, and WRT declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. PF and FA are employed at Zimmer Biomet, the company producing the Innex implant investigated here., (© 2024. The Author(s).)

This research assessed the influence of various heel elevation conditions on spinal kinematic and kinetic data during loaded (25% and 50% of body weight) high-bar back squats. Ten novice (mass 67.6 ± 12.4 kg, height 1.73 ± 0.10 m) and ten regular weight trainers (mass 66.0 ± 10.7 kg, height 1.71 ± 0.09 m) completed eight repetitions at each load wearing conventional training shoes standing on the flat level floor ( LF ) and on an inclined board ( EH ). The regular weight training group performed an additional eight repetitions wearing weightlifting shoes ( WS ). Statistical parametric mapping (SPM1D) and repeated measures analysis of variance were used to assess differences in spinal curvature and kinetics across the shoe/floor conditions and loads. SPM1D analyses indicated that during the LF condition the novice weight trainers had greater moments around L4/L5 than the regular weight trainers during the last 20% of the lift ( P <  0.05), with this difference becoming non-significant during the EH condition. This study indicates that from a perspective of spinal safety, it appears advantageous for novice weight trainers to perform back squats with their heels slightly elevated, while regular weight trainers appear to realize only limited benefits performing back squats with either EH or WS .