Influence of press-fit parameters on the primary stability of uncemented femoral resurfacing implants

The Effect of Surface Morphology on the Primary Fixation Strength of Uncemented Femoral Knee Prosthesis: A Cadaveric Study

“…That study showed a significantly lower micromotion of a hip stem with a rougher surface under cyclic loading. Gebert et al [22] found a positive effect of friction coefficient on the fixation strength of an uncemented femoral resurfacing implant in a finite element study. Hence, improvement of fixation strength in the femoral knee component as a result of rougher surface morphology corresponds to previous studies, although in the current study a different implant design was analyzed.…”

Primary stability of uncemented femoral resurfacing implants for varying interface parameters and material formulations during walking and stair climbing

“…Since the relationship between independent and dependent variables was nonlinear, all variables were transformed logarithmically to linearize the data. The FE model was validated by comparing the numerically determined torque-angle characteristic for a given nominal interference with experimental data available for the modeled specimen for one of the investigated implant conditions (Gebert et al, 2008). In this study of Gebert et al, …”

“…In most cases, predominantly linear elastic material models based on patientspecific heterogeneous bone density distributions were used (Reggiani et al, 2007;Viceconti et al, 2000). However, these models do not account for post-yield behavior of the bone (Morgan and Keaveny, 2001;Bayraktar et al, 2004), which could lead to stagnating contact pressure with increasing interference and consequently might compromise primary stability (Natali et al, 2009, Gebert et al, 2008. Recently, a homogeneous elasticplastic material formulation was used to show that, for typical press-fit interferences of 0.05-0.2 mm, bone is loaded beyond its yield limit (Gebert et al, 2008).…”

“…However, these models do not account for post-yield behavior of the bone (Morgan and Keaveny, 2001;Bayraktar et al, 2004), which could lead to stagnating contact pressure with increasing interference and consequently might compromise primary stability (Natali et al, 2009, Gebert et al, 2008. Recently, a homogeneous elasticplastic material formulation was used to show that, for typical press-fit interferences of 0.05-0.2 mm, bone is loaded beyond its yield limit (Gebert et al, 2008). The purpose of this study therefore was to investigate the influence of press-fit and bone quality on the primary stability and consequent bone ingrowth of uncemented femoral resurfacing designs under physiological loading conditions.…”

The Effects of Interfacial Conditions and Stem Length on Potential Failure Mechanisms in the Uncemented Resurfaced Femur

“…7,19 While investigating the effect of press-fit parameters on the primary stability of uncemented femoral implants, Gebert et al 7 predicted increasing stability with greater actual interference, better bone quality, and greater friction coefficient. Ong et al 19 is the only study that investigated the effects of different methods of fixation (cemented vs. uncemented) and different interface conditions (bonded vs. debonded) on the load transfer of a resurfaced femur implanted with the BHR, using 3D FE models.…”