A novel analytical approach for determining the frictional moments and torques acting on modular femoral components in total hip replacements

Farhoudi, Hamidreza; Oskouei, Reza Hashemi; Jones, Claire F.; Taylor, Mark

doi:10.1016/j.jbiomech.2015.02.010

Cited by 17 publications

(19 citation statements)

References 27 publications

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“…The friction coefficient is a function of lubrication regime, material combination, and bearing geometry, and varies throughout the activity cycle. An analysis previously conducted on different bearing couples (metal-on-metal, metal-on-polyethylene, metal-on-ceramic, and ceramic-on-ceramic) showed that, for metal-on-metal bearing couples, assuming a constant friction coefficient (corresponding to the maximum contact force) was in good agreement with in vitro experimental results for a simplified activity cycle [23]. The accuracy of using a constant friction coefficient for determining frictional moments in hard-on-hard bearing couples has been justified and presented previously [23].…”

Section: Methodsmentioning

confidence: 91%

“…This simplification cannot be expanded to a quantitative 6 DOF study as the system is indeterminant. Assuming a constant friction coefficient for hard-on-hard couples (combinations of metals and/or ceramics) in a 6 DOF problem is justified for the purpose of finding maximum values, changes of direction, and an overall trend of variation in frictional moment [23]. This assumption was successfully validated in the previous work [23], where good agreement was found between the experimental and analytical frictional moment results for hard-on-hard bearing couples, mainly as a result of the direct relationship between the contact force and friction coefficient in these couples.…”

Section: Methodsmentioning

confidence: 99%

“…The calculated frictional moment was then projected onto the instantaneous axis of the neck to obtain the torque acting on the neck within the junction ( M n ). A detailed description of the analytical approach for formulating frictional moment ( M f ) has been described previously [23].

M_{f} = 140%true \int D \cdot μ_{k} \cdot p \cdot d A

…”

Section: Methodsmentioning

confidence: 99%

“…However, frictional moments measured for a specific head-cup bearing couple configuration cannot be generalized to other bearing with different geometries and material combinations. Frictional moments are dependent on the friction coefficient of the bearing couple, the lubrication regime, the bearing clearance, the size of the implant, and the geometry and material combination of the bearing couple [10,11,23]. Thus, the state space including all material combinations, geometries (head-cup sizes, neck offset, and version/anti-version), and daily activities is too large to be studied by in vivo experimental methods.…”

Section: Introductionmentioning

confidence: 99%

“…The authors, in their previous work [23], introduced and detailed a new methodology to analytically determine frictional moments at the head-cup bearing couple of a total hip replacement. The theoretical frictional moment results were successfully verified against experimental results for a simplified gait cycle reported by Bishop et al [11].…”

Section: Introductionmentioning

confidence: 99%

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An Analytical Calculation of Frictional and Bending Moments at the Head-Neck Interface of Hip Joint Implants during Different Physiological Activities

et al. 2016

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This study predicts the frictional moments at the head-cup interface and frictional torques and bending moments acting on the head-neck interface of a modular total hip replacement across a range of activities of daily living. The predicted moment and torque profiles are based on the kinematics of four patients and the implant characteristics of a metal-on-metal implant. Depending on the body weight and type of activity, the moments and torques had significant variations in both magnitude and direction over the activity cycles. For the nine investigated activities, the maximum magnitude of the frictional moment ranged from 2.6 to 7.1 Nm. The maximum magnitude of the torque acting on the head-neck interface ranged from 2.3 to 5.7 Nm. The bending moment acting on the head-neck interface varied from 7 to 21.6 Nm. One-leg-standing had the widest range of frictional torque on the head-neck interface (11 Nm) while normal walking had the smallest range (6.1 Nm). The widest range, together with the maximum magnitude of torque, bending moment, and frictional moment, occurred during one-leg-standing of the lightest patient. Most of the simulated activities resulted in frictional torques that were near the previously reported oxide layer depassivation threshold torque. The predicted bending moments were also found at a level believed to contribute to the oxide layer depassivation. The calculated magnitudes and directions of the moments, applied directly to the head-neck taper junction, provide realistic mechanical loading data for in vitro and computational studies on the mechanical behaviour and multi-axial fretting at the head-neck interface.

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Section: Methodsmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%