Polyethylene liner motion in dual-mobility hip prostheses: static and dynamic radiostereometry in 16 patients 1 year after operation

Peter Bo  Jørgensen; Bart L Kaptein; Kjeld Søballe; Stig S Jakobsen; Maiken Stilling

doi:10.2340/17453674.2022.2253

Authors

Peter Bo Jørgensen AutoRSA Research Group, Orthopeadic Research Unit Aarhus University Hospital, Aarhus https://orcid.org/0000-0002-5327-8095
Bart L Kaptein Biomechanics and Imaging Group, Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands https://orcid.org/0000-0001-8772-9985
Kjeld Søballe AutoRSA Research Group, Orthopaedic Research Unit, Aarhus University Hospital, Aarhus, Denmark; Biomechanics and Imaging Group, Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands
Stig S Jakobsen Department of Orthopaedic Surgery, Aarhus University Hospital, Aarhus N, Denmark
Maiken Stilling AutoRSA Research Group, Orthopaedic Research Unit, Aarhus University Hospital, Aarhus, Denmark; Department of Orthopaedic Surgery, Aarhus University Hospital, Aarhus N, Denmark https://orcid.org/0000-0002-4530-2075

DOI:

https://doi.org/10.2340/17453674.2022.2253

Keywords:

Dual mobility, Dynamic radiostereometry, Hip osteoarthritis, Kinematics

Abstract

Background and purpose: Dual-mobility hip arthroplasty utilizes a freely rotating polyethylene acetabular liner to protect against dislocation. As liner motion has not been confirmed in vivo, we undertook this using dynamic radiostereometry (RSA).

Patients and methods: 6 patients with Anatomical Dual Mobility acetabular components were included. Markers were implanted in the liners using a drill guide. Static RSA recordings and patient-reported outcome measures were obtained postoperatively and at 1-year follow-up. Dynamic RSA recordings were obtained at 1-year follow-up during passive hip movement: abduction/external rotation, adduction/internal rotation (modified FABER–FADIR), to end-range and at 45° hip flexion. Liner and neck movements were described as anteversion, inclination, and rotation.

Results: Liner movement during modified FABER–FADIR was detected in 12 of 16 patients. Median (range) absolute liner movements were: anteversion 10° (5–20), inclination 6° (2–12), and rotation 11° (5–48) relative to the cup. Median absolute change in the resulting liner/neck angle (small articulation) was 28° (12–46) and in liner/cup angle (larger articulation) was 6° (4–21). Static RSA showed changes in median liner anteversion from 7° (−12 to 23) postoperatively to 10° (−3 to 16) at 1-year follow-up and inclination from 42° (35–66) postoperatively to 59° (46–80) at 1-year follow-up. Liner/neck contact was associated with high initial liner anteversion (p = 0.01).

Interpretation: The polyethylene liner moves over time. 1 year after surgery the liner can move with or without liner/neck contact. The majority of movement is in the smaller articulation between head and liner.