Related Experiment Video
Updated: Aug 19, 2025
In Vivo Quantification of Hip Arthrokinematics during Dynamic Weight-bearing Activities using Dual Fluoroscopy
Published on: July 2, 2021
Combined kinematic cup alignment reduces the rate of impingement and edge loading compared to mechanical and
Thomas Aubert1, Pierre-Alban Bouche2
1Orthopaedic Department, Croix Saint Simon Hospital, 125 Rue d'Avron, 75020 Paris, France.
Introduction:
In recent years, different alignments have been described for acetabular components in total hip arthroplasty (THA), to reduce the risk of impingement and edge loading. Currently there are 3 main options: mechanical (40° inclination/15° anteversion relative to the anterior pelvic plane), anatomic (40° inclination/anteversion parallel to the transverse ligament) and combined kinematic (according to spinal-pelvic parameters). There are no studies comparing all three in terms of impingement and edge loading. We therefore performed a retrospective case-control in-vitro study comparing risk of impingement and edge loading between the three alignments.
Hypothesis:
The study hypothesis was that combined kinematic alignment incurs significantly less risk of impingement and edge loading than do the other two types of alignment.
Methods:
Using a THA planning system, we simulated the 3 alignments for 90 patients undergoing THA with a ceramic-on-ceramic bearing between November 2019 and January 2022; for each simulation, we recorded any prosthetic impingement or edge loading. The study endpoint was the rate of prosthetic impingement or edge loading between the 3 alignments.
Results:
With the mechanical alignment, 31% of patients (28/90) showed risk of impingement and 22% (20/90) risk of edge loading. With the anatomic alignment, 31% of patients (28/90) showed risk of impingement and 23.3% (21/90) risk of edge loading. With the combined kinematic alignment, 12.2% of patients (11/90) showed risk of impingement and 8.9% (8/90) risk of edge loading. Pairwise comparison showed that the combined kinematic alignment was associated with significantly less impingement and edge loading than the mechanical alignment (respectively, p=0.03 and p=0.022) or the anatomic alignment (respectively, p=0.03 and p=0.014), while the mechanical and anatomic alignments did not differ.
Conclusion:
A combined kinematic cup alignment in THA significantly reduced the risk of impingement and edge loading compared to mechanical and anatomic alignments.
Level Of Evidence:
III, retrospective case-control study.
