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

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.

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.

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.

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.

Patient-reported return to sports (yes/no) and time to return to sports (months) will be assessed at 1 year postoperatively.

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.

Patient-reported return to sexual activity (yes/no) and time to return to sexual activity (months) will be assessed at 1 year postoperatively.

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).

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.

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.

Association between age and the FJS at 2 years.

Association between sex and the FJS at 2 years.

Association between body mass index and the FJS at 2 years.

Association between preoperative hip pain and the FJS at 2 years.

Association between preoperative Oxford Hip Score and the FJS at 2 years.

Association between preoperative range of motion and the FJS at 2 years.

Association between preoperative University of California Los Angeles activity score and the FJS at 2 years.

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?