Parametric analysis of the effect of impaction load on the stability of head-neck junction in total hip arthroplasty

Background: Tribocorrosion at head-neck interface is one of the main causes leading to the failure of hip implants in total hip arthroplasty. Impaction load has been acknowledged as one of the key factors influencing the stability of the taper junction. It is understood that the magnitude of impaction force differs from the surgeon to surgeon in primary total hip arthroplasty or revision. Clinically, it is sufficient enough to keep the male and female tapers inseparable utilizing a low impaction, which seems to contradict previous researches. The objective of this study was to investigate the effect of impaction loads on the stability of taper junction during assembly and gaits. Methods: A finite element model with 12/14 taper and the taper mismatch of 4′ was developed for investigation. The impaction force profiles were collected from surgeon as the inputs, and then the contact mechanics over one or multiple gaits was further analyzed and validated utilizing hip simulator test. Findings: Impaction force ranging from 200 to 2000 N could provide the same taper connection effect after the first gait due to the secondary seating. As for impaction loads of 3000 N and above, an increased impaction force would lead to the tighter taper connection. Interpretation: The effect of impaction load on the stability of head-neck junction is a piecewise function, indicating that the stability of taper junction is not affected by different impaction loads and tends to be consistent while its magnitude is below the threshold. Instead, the stability of taper junction is positively correlated with impaction force.