Overview
This is a single-centre, randomized, double-blinded controlled non-inferiority trial that will be conducted at the Orthopaedic Department at Uppsala University Hospital, Uppsala. The aim of the study is to evaluate the performance of a dual mobility acetabular component with a Vitamin E-infused highly crosslinked polyethylene (VEPE) liner compared to a conventional polyethylene (PE) liner in adult patients with symptomatic osteoarthritis, osteonecrosis, or dysplasia of the hip requiring a hip replacement. The assessments will focus on early wear, cup migration, adverse events, and clinical outcomes. Measurements will be conducted using Computed Tomography Radiostereometric Analysis (CT-RSA) instead of traditional radiostereometric analysis. The study hypothesis is that the PE liner will be non-inferior to the VEPE liner in terms of early wear over a two-year period.
Description
Dual-mobility cups (DMCs) were introduced to reduce the risk of dislocation after total hip arthroplasty (THA) by improving stability while maintaining a large range of motion. Concerns remain regarding polyethylene liner wear due to the larger articulating surface, as wear rates exceeding 0.1 mm/year have been associated with osteolysis and aseptic loosening. Vitamin E-infused highly crosslinked polyethylene (VEPE) has been developed to improve wear resistance, and CT-based radiostereometric analysis (CT-RSA) provides a validated method for assessing implant wear and migration.
The BiMobile Dual Mobility System (Waldemar LINK GmbH) is designed to enhance stability and wear resistance through biocompatible materials and self-centering liners. Although clinical evidence specifically for the BiMobile cup is limited, studies of dual-mobility implants have reported low wear, limited migration, high implant survival, and low rates of loosening.
This study aims to evaluate the performance of the BiMobile dual-mobility cup with a VEPE liner compared with a conventional polyethylene (PE) liner. In a single-centre, randomized, double-blinded non-inferiority trial, patients undergoing THA will be followed for up to five years. The primary objective is to compare in vivo liner wear at two years using CT-RSA. Secondary objectives include evaluation of wear at five years, cup migration and fixation, patient satisfaction, adverse events, and patient-reported outcomes.
All participants will receive a BiMobile dual-mobility cup and will be randomized to either a VEPE or conventional PE liner. CT-RSA examinations will be performed postoperatively and at 6 months, 2 years, and 5 years to measure polyethylene wear, cup migration, and radiological signs of loosening. The study will provide important post-market evidence regarding the long-term safety, fixation, and wear characteristics of the BiMobile system and may help determine whether dual-mobility cups can be more widely used in younger and more active patients.
Eligibility
Inclusion Criteria:
- Age 18-75 years
- Written informed consent
- Eligible for a Total Hip Arthroplasty according to local guidelines and appropriate candidate for a dual mobility concept
- Diagnosis: Symptomatic osteoarthritis, osteonecrosis, or dysplasia of the hip requiring a hip replacement
Exclusion Criteria:
- Confirmed dementia or cognitive impairment
- Unwillingness to give written informed consent
- Age \<18 or \>75 years
- Hip fracture (traumatic or pathological) in need of a Total Hip Arthroplasty
- Patients who are not deemed suitable for a THA with a Dual Mobility Cup according to local guidelines and routines
- Comorbidities that are contraindicators for hip replacement surgery
