Comparing Dual-mobility Cups Versus Unipolar Cups for Unselected Primary Total Hip Arthroplasty by Direct Anterior Approach (DUALSIM-THA)

Monocentric Randomised Controlled Trial Comparing Dual-mobility Cups Versus Unipolar Cups for Unselected Primary Total Hip Arthroplasty by Direct Anterior Approach

THA comprises the replacement of the damaged bone and cartilage with prosthetic components. The proximal end of the femur is replaced with a stem and ball/head, while the acetabulum is most commonly replaced with a unipolar cup (UP) that consists of a liner inside of a metal shell. UP cups are associated with risks of dislocations, especially in elderly and female patients, as well as in patients with lumbar stiffness or operated for femoral neck fractures. In fact, one of the most common reasons for early revision of UP cups are dislocations.

Dual-mobility (DM) cups were introduced in the 1970s by the French surgeon Gilles Bousquet, as an alternative to UP cups. They are made up of two articulations, a femoral head moving inside a mobile polyethylene liner, which in turn moves inside a metal shell. This design allows for a greater jump distance and range of motion (ROM) compared to UP cups, thus resulting in reduced rates of dislocation.

A recent systematic review that evaluated 5 case-control studies (549 DM cups vs 649 UP cups) and 3 registry studies (5935 DM cups vs 217362 UP) found that in case-control studies, the dislocation rates were 0.2% for DM cups versus 7.1% for UP cups (p=0.009). Furthermore, in registry studies the revision rates due to dislocation were 0.2% for DM cups versus 0.5% for UP cups (p=0.050).

Nonetheless, there have been some concerns associated with the use of DM cups, including intra-prosthetic dislocations (IPD), polyethylene wear, and iliopsoas impingement. Since the early 2000s, new improvements in the design of DM cups have nearly eliminated the risk of IPD, and the use of ultra-high molecular weight polyethylene (UHMWPE) has greatly reduced wear rates, even in young and active patients. Lastly, although some studies have reported iliopsoas impingement with DM cups, the impingement is usually against the optional fixations, and not against the mobile polyethylene insert.

The hypothesis of the present interventional randomised controlled trial (RCT) is that THA using DM cups will not provide inferior outcomes compared to THA using UP cups, in terms of hip awareness measured using the forgotten joint score (FJS).

Study Overview

• Status: Not yet recruiting
• Conditions: Primary Total Hip Arthroplasty; Primary Total Hip Replacement
• Intervention / Treatment: Procedure: Primary total hip arthroplasty using dual-mobility cup; Procedure: Primary total hip arthroplasty using unipolar cup

• Study Type: Interventional
• Enrollment (Estimated): 300
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Nicolas Verdier; Phone Number: +33(0)535549569; Email: dr.nicolas.verdier@gmail.com
• Study Contact Backup: Name: Charlène Py; Phone Number: +33(0)556003048; Email: charlene.py@elsan.care

Study Locations

• France
  • Bruges, France, 33520
    • Polyclinique Jean Villar
    • Contact: Nicolas Verdier; Phone Number: +33(0)535549569; Email: dr.nicolas.verdier@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• men and women aged ≥18 years old
• set to undergo elective primary THA via direct anterior approach (DAA)
• affiliated with a social security scheme
• able to answer questionnaires and to communicate freely in French
• who have been informed and have provided free, informed, and written consent (no later than the day of inclusion and before any examination required by the study)

Exclusion Criteria:

• with prior ipsilateral hip surgery
• with prior contralateral hip surgery
• that require acetabular cup diameters ≤50mm (because DM cups are not available from the same manufacturer for diameters ≤50mm, and UP cups require head diameters of 36mm and thus minimum cup diameters of 52mm)
• undergoing emergency or trauma surgery (e.g. femoral neck fractures)
• with any concomitant disease or disorder which, in the opinion of the surgeon, may put the patient at risk, notably of hip instability or dislocation (hip dysplasia, neuromuscular deficit, fracture sequelae…) or may influence the result of the study
• that are pregnant or breastfeeding
• under legal protection (guardianship or curatorship or deprived of liberty).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: THA with dual-mobility cup; The THA will be performed via the DAA. The liner will be made of highly-crosslinked vitamin-E infused polyethylene. The femoral head will be made of either metal or ceramic. The dual-mobility cup will always be cementless, while the stem will be cemented in female patients aged ≥75 years, as well as in any patient diagnosed with osteoporosis. A blunt dissection will be carried out through the tensor fasciae latae muscle (TFLM), between the sartorius and rectus femoris muscles. A femoral neck osteotomy will then be performed using an oscillating saw, and the femoral head will be removed with a corkscrew. The acetabular components and the selected liner according to the randomisation, will then be implanted.The femoral head will then be impacted onto the femoral stem, and the prosthesis will be reduced. Closure of the surgical site will be performed in layers.	Procedure: Primary total hip arthroplasty using dual-mobility cup; Replacement of hip articulating surface.; Other Names: THA; THR; Primary total hip replacement
Active Comparator: THA with unipolar cup; The THA will be performed via the DAA. The liner will be made of highly-crosslinked vitamin-E infused polyethylene. The femoral head will be made of either metal or ceramic. The unipolar cup will always be cementless, while the stem will be cemented in female patients aged ≥75 years, as well as in any patient diagnosed with osteoporosis. A blunt dissection will be carried out through the tensor fasciae latae muscle (TFLM), between the sartorius and rectus femoris muscles. A femoral neck osteotomy will then be performed using an oscillating saw, and the femoral head will be removed with a corkscrew. The acetabular components and the selected liner according to the randomisation, will then be implanted.The femoral head will then be impacted onto the femoral stem, and the prosthesis will be reduced. Closure of the surgical site will be performed in layers.	Procedure: Primary total hip arthroplasty using unipolar cup; Replacement of hip articulating surface.; Other Names: THA; THR; Primary total hip replacement

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forgotten Joint Score between DM cup group and UP cup group	The primary outcome is defined as patient-reported hip awareness at 2 years postoperatively, measured using the Forgotten Joint Score (FJS). The FJS is a validated self-administered questionnaire that measures the patients' ability to forget about a joint as a result of successful treatment. The questionnaire comprises 12 items. Each item is scored using a 5-point Likert scale, ranging from "never" (0 points) to "mostly" (4 points). The final FJS score is calculated as the addition of all items, divided by the number of items answered. The mean score is then multiplied by 25, and that value is subtracted from 100. The FJS ranges from 0 to 100, with 100 corresponding to the best score: the patient has forgotten about their joint.	2 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forgotten Joint Score between DM cup group and UP cup group	Patient-reported hip awareness at 3 months and 1 year postoperatively, measured using the FJS. The FJS is a validated self-administered questionnaire that measures the patients' ability to forget about a joint as a result of successful treatment. The questionnaire comprises 12 items. Each item is scored using a 5-point Likert scale, ranging from "never" (0 points) to "mostly" (4 points). The final FJS score is calculated as the addition of all items, divided by the number of items answered. The mean score is then multiplied by 25, and that value is subtracted from 100. The FJS ranges from 0 to 100, with 100 corresponding to the best score: the patient has forgotten about their joint.	3 months and 1 year
To compare the patient's hip/groin pain between DM cups versus UP cups, as well as to compare the net change from baseline	Patient-reported hip/groin pain preoperatively and at 3 months, 1 year and 2 years postoperatively, measured using a numeric rating scale (NRS). The net change will be calculated at 3 months, 1 year and 2 years taking the preoperative value as baseline. The NRS ranges from 0 to 10, with 0 representing no pain, and 10 representing the maximum pain imaginable.	preoperatively, at 3 months, 1 year and 2 years
To compare the patient's hip function between DM cups versus UP cups	Patient-reported hip function preoperatively and at 3 months, 1 year and 2 years postoperatively, measured using the Oxford hip score (OHS). The OHS is a validated self-administered questionnaire that assesses disability, in terms of function and pain, in patients undergoing THA. The questionnaire comprises 12 items. Each item is scored using a 5-point Likert scale, from 0 to 4 points, with 0 representing the worst outcome and 4 the best. The final OHS score is calculated as the addition of all items. The OHS ranges from 0 to 48, with 48 corresponding to the best score. Clinician-reported hip ROM preoperatively and at 3 months and 1 year postoperatively. ROM will be measured in degrees, in flexion, extension, internal rotation, external rotation, abduction, adduction.	preoperatively, at 3 months, 1 year and 2 years
To compare the patient's sports activity between DM cups versus UP cups	Patient-reported return to sports (yes/no) and time to return to sports (months) will be assessed at 1 year postoperatively.	1 year
To compare the patient's sports activity between DM cups versus UP cups	The University of California Los Angeles (UCLA) activity score will be evaluated preoperatively, at 1 year and 2 years postoperatively. The UCLA activity score assesses physical activity in patients undergoing hip surgery. The questionnaire is a single-item 10-level-scale, ranging from 1-10, with 10 representing a highly physically active patient, and 1 representing a patient who is dependent on others and unable to leave home.	preoperatively, at 1 year and 2 years
To compare the patient's sexual activity between DM cups versus UP cups	Patient-reported return to sexual activity (yes/no) and time to return to sexual activity (months) will be assessed at 1 year postoperatively.	1 year
To compare the patient's sexual activity between DM cups versus UP cups	If the patient has returned to sexual activities, they will be asked to complete the questionnaire developed by Rougereau et al.. The questionnaire has 3 items, each of which is presented separately: (i) frequency of sexual intercourse after THA compared to before THA (unable to perform intercourse, unchanged, decreased, increased); (iia) difficulties with resuming sexual activity (yes, no), if yes, (iib) for what reason? (apprehension, pain, discomfort, decreased libido, other); and (iiia) change in sexual positions compared to before THA (unable to perform intercourse, temporary, definitive, none), if temporary, (iiib) for how long? (less than 3 weeks, more than 3 weeks).	1 year
To compare the patient's satisfaction with surgery between DM cups versus UP cups	Patient-reported satisfaction with surgery at 1 year postoperatively, measured using a NRS. The NRS ranges from 0 to 10, with 0 representing extremely dissatisfied, and 10 representing extremely satisfied.	1 year
To compare adverse events (that may impact the objectives of the study) between DM cups versus UP cups	Adverse events that may impact the objectives of the study, as well as complications (e.g. fracture, infection, hematoma, limb length discrepancy, aseptic loosening, articular noise), reoperations, and implant revisions, will be collected throughout the study period, specifying the incidence, severity, and relationship to the surgery performed. Adverse events of interest will be dislocations and iliopsoas impingement.	intraoperatively, at 3 months, 1 year and 2 years

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
To evaluate whether age is associated with the Forgotten Joint Score	Association between age and the FJS at 2 years.	2 years
To evaluate whether sex is associated with the Forgotten Joint Score	Association between sex and the FJS at 2 years.	2 years
To evaluate whether body mass index is associated with the Forgotten Joint Score	Association between body mass index and the FJS at 2 years.	2 years
To evaluate whether preoperative hip pain is associated with the Forgotten Joint Score	Association between preoperative hip pain and the FJS at 2 years.	2 years
To evaluate whether preoperative Oxford Hip Score is associated with the Forgotten Joint Score	Association between preoperative Oxford Hip Score and the FJS at 2 years.	2 years
To evaluate whether preoperative range of motion is associated with the Forgotten Joint Score	Association between preoperative range of motion and the FJS at 2 years.	2 years
To evaluate whether preoperative University of California Los Angeles activity score is associated with the Forgotten Joint Score	Association between preoperative University of California Los Angeles activity score and the FJS at 2 years.	2 years
To compare the patient's experience regarding their care during hospitalisation between DM cups versus UP cups	Patient-reported experience regarding their care during hospitalisation will be measured at 3 months using the questionnaire developed by Benson et al.. The questionnaire comprises 4 items rated on a 4-point scale (excellent, good, fair, poor): (i) were you treated kindly?, (ii) were you listened and explained?, (iii) were you seen promptly?, (iv) were things well organised?	3 months

Collaborators and Investigators

• Sponsor: Elsan

Publications and helpful links

General Publications

• Jones HB, Hinkle AJ, Liu Y, Sambandam SN. Multivariate Analysis of Risk Factors for In-Hospital Dislocation Following Primary Total Hip Arthroplasty. J Clin Med. 2024 Jun 13;13(12):3456. doi: 10.3390/jcm13123456.
• Fessy MH, Viste A, Philippot R, Belzile EL. Recent progress in dual mobility total hip arthroplasty: an irresistible French icon. Orthop Traumatol Surg Res. 2024 Oct;110(6):103993. doi: 10.1016/j.otsr.2024.103993. Epub 2024 Sep 10. No abstract available.
• Jonker RC, van Beers LWAH, van der Wal BCH, Vogely HC, Parratte S, Castelein RM, Poolman RW. Can dual mobility cups prevent dislocation without increasing revision rates in primary total hip arthroplasty? A systematic review. Orthop Traumatol Surg Res. 2020 May;106(3):509-517. doi: 10.1016/j.otsr.2019.12.019. Epub 2020 Apr 8.
• Varacallo MA, Luo TD, Johanson NA. Total Hip Arthroplasty Techniques. 2023 Aug 4. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from http://www.ncbi.nlm.nih.gov/books/NBK507864/

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): June 1, 2030
• Study Completion (Estimated): June 1, 2030

Study Registration Dates

• First Submitted: March 2, 2026
• First Submitted That Met QC Criteria: March 6, 2026
• First Posted (Actual): March 11, 2026

Study Record Updates

• Last Update Posted (Actual): March 11, 2026
• Last Update Submitted That Met QC Criteria: March 6, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: total hip arthroplasty; RCT; randomised controlled trial; THA; total hip replacement; THR; unipolar cup; dual-mobility cup
• Additional Relevant MeSH Terms: Heterocyclic Compounds; Heterocyclic Compounds, Fused-Ring; Heterocyclic Compounds, 3-Ring; Aminoacridines; Acridines; Tacrine
• Other Study ID Numbers: 2025-A01817-42

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No