Experimental measurements of femoral primary stability in two cementless posterior-stabilized knee replacement implants

The influence of body weight index on initial stability of uncemented femoral knee protheses: A finite element study

“…Micromotion is an essential indicator for evaluating the initial stability of the prosthesis. Some experimental or simulation studies used simplified loading conditions, such as peak axial load during gait representing the worst scenarios [ 21 , 48 ]. However, previous studies showed that the maximum micromotion did not occur at the peak axial load time point [ [49] , [50] , [51] ], consistent with the present study ( Fig.…”

“…Excessive interfacial micromotion can affect this biological fixation [ 12 ]. Experimental studies are the golden standard for obtaining micromotion [ 14 , 21 , 22 ]. Nevertheless, they also have limitations.…”

Pre-clinical characterization of a novel flexible surface stem design for total knee replacements

“…The measured relative movements are comparable to published relative movements or micromotions. 14,18,22,24,32,44 However, this parameter does not represent the micromotions in the bone-implant interface only, since both shear deformation at the interface and elastic deflection of the surrounding bone and/or implant components are superimposed. 32 In case of the flexible surface stem specimens, the elasticity of the lamellas influences the measured relative movements but not necessarily increase the micromotions at the bone-implant interface.…”

“…Within this study, only one loading scenario was used to evaluate the primary stability. However, it was shown that the loading scenario 22 and the flexion angle 18,56 influences the relative movement between TKR and bone. Additionally, only an axial loading was applied, however, in the standard ASTMF31431-17a 42 and in a comparable study 14 a torque of 5 Nm was simultaneously defined to represent acting loads in the knee joint.…”

“…21 In pre-clinical testing, primary implant stability is evaluated by the relative movements between bone and implant during physiological loading. 14,18,19,[22][23][24][25] It is influenced by bone density, surgical technique, implant material and design, the level of press-fit, and the magnitude and direction of the physiological loads. 14,18,19,23,24,[26][27][28][29] Regarding the response of human bone cells, small micromotions at the boneimplant interface are improving cell differentiation and bone formation at the interface.…”