Combined kinematic cup alignment reduces the rate of impingement and edge loading compared to mechanical and anatomical alignment. An in-vitro case-control study - 25/11/22

Doi : 10.1016/j.otsr.2022.103468

Thomas Aubert ^a, Pierre-Alban Bouche ^a,^b,⁎
^a Orthopaedic Department, Croix Saint Simon Hospital, 125 Rue d’Avron, 75020 Paris, France
^b Orthopaedic Department, Lariboisière Hospital, APHP, 2 Rue Ambroise Paré, 75010 Paris, France

^⁎Corresponding author. Orthopaedic Department, Croix St Simon Hospital, 125 Rue d’Avron, 75020 Paris, France.Orthopaedic Department, Croix St Simon Hospital125 Rue d’AvronParis75020France

Sous presse. Épreuves corrigées par l'auteur. Disponible en ligne depuis le Friday 25 November 2022
Cet article a été publié dans un numéro de la revue, cliquez ici pour y accéder

Abstract

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.