1 3 Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-015-3514-y KNEE Knee kinetics and kinematics: What are the effects of TKA malconfigurations? Silvia Pianigiani · Luc Labey · Walter Pascale · Bernardo Innocenti Received: 29 July 2014 / Accepted: 12 January 2015 © European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2015 Results The results from this study show that contact forces (with changes up to 67 %) are more heavily affected by malconfigurations than kinematics, for which maxi- mum deviations are of the order of 5 mm or 5°, similar to the simulated surgical errors. The results present a similar trend for the different designs. Conclusions The results confirm the hypothesis that kinematics is not the only and also not the most relevant parameter to predict or explain knee function after TKA. In the future, techniques to analyse knee kinetics should be integrated in the clinical follow-up. Keywords Knee kinematics · Knee contact forces · TKA performance · Malconfigurations · Clinical follow-up Introduction Although total knee arthroplasty (TKA) is a very success- ful surgical procedure [25], implant failures and patient dis- satisfaction still persist. Typically, follow-up examination is based on manual testing by the surgeon, medical imaging, the subjective assessment of activities performed by the patient, and the use of questionnaires and clinical scores [21, 36]. Rarely, more thorough patient investigations, including joint kin- ematics analyses using fluoroscopy [1, 32] or 3D motion capture [2, 4, 7], are used. For research purposes, the use of instrumented knee prostheses to obtain both kinematics and kinetics informa- tion has been documented in literature [27, 45], but this is limited to a small group of patients with specific TKA designs and aimed at analysing internal tibio-femoral contact forces. Contact forces in the knee joint can also be predicted by integrating 3D motion capture with force Abstract Purpose Total knee arthroplasty (TKA) is a very suc- cessful surgical procedure. However, implant failures and patient dissatisfaction still persist. Sometimes surgeons are not able to understand and explain these negative perfor- mances because the patient’s medical images “look good”, but the patient “feels bad”. Apart from radiograph imaging and clinical outcome scores, conventionally used follow-up methods are mainly based on the analysis of knee kinemat- ics. However, even if kinematics remains close to the “nor- mal” range of motion, the patient may still complain about pain and functional limitations. To provide more insight into this paradox, a better quantitative understanding of TKA mechanics must be developed. For this purpose, improved techniques for clinical follow-up, combining kinetics and kinematics analysis, should be introduced to help surgeons to assess and understand TKA performance. Methods An analysis on four TKA designs was per- formed, and the changes in kinematics and in kinetics induced by several implant configurations (simulating implant malalignment and different knee anatomy) were compared. More specifically, analysed tibio-femoral and patello-femoral contact forces and tibio-femoral kinematics were analysed during a squat task up to 120°. S. Pianigiani (*) · W. Pascale IRCCS Istituto Ortopedico Galeazzi, Via R. Galeazzi 4, 20161 Milan, Italy e-mail: silvia.pianigiani84@gmail.com L. Labey Biomechanics Section, KU Leuven, Celestijnenlaan 300C, 3001 Louvain, Belgium B. Innocenti BEAMS Department, Université Libre de Bruxelles, Avenue Roosevelt 50, 1050 Brussels, Belgium