This study was written according to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines (Checklist 1) for protocols of randomized clinical trials. The proposal is a single-center, single-surgeon, single-approach, pragmatic, double-blinded, prospective randomized trial to analyze the differences between uncemented hip replacement and the hybrid (femoral cemented) hip replacement.

Two different types of hip implants will be used for comparison: the Maxima Cemented Vincula Stem (Víncula, Rio Claro, SP, Brazil) and the Taper Uncemented Primary Stem (Víncula, Rio Claro, SP, Brazil). Patients and evaluators will be blinded to group allocation: the hybrid group (HG) and the uncemented group (UG). A total of 120 patients will be enrolled in this study and randomly allocated to each group in a 1:1 ratio.

All the patients ascribed to a waiting list for hip arthroplasty in a hip reconstruction ambulatory of a tertiary teaching hospital in Juiz de Fora-MG, in southeast Brazil (Hospital e Maternidade Therezinha de Jesus) will form the recruitment base for this study. This study was approved by an institutional review board, registered in the Brazilian Registry of Clinical Trials (RBR-263nf22), and assigned the Universal Trial Number U1111-1313-6912. All eligible patients will be informed verbally about the study and its objectives and will be invited to participate (Figure 1). All exclusions will be recorded and reported. Patients who consent to participate will be invited for a consultation when they sign a written informed consent form and will be assigned a sequential study number.

Standard digital anteroposterior pelvis radiographs with calibration spheres will be obtained. A clinical interview and thorough preoperative evaluation will be undertaken by a medical doctor (orthopedic surgery resident). Functional, pain, and QoL questionnaires will be administered at this point, and surgical appointments will be scheduled (Multimedia Appendix 1).

Patient assignment and preoperative evaluations will be conducted in monthly blocks of 12 patients for practical and logistic purposes. Random allocation of patients to each group, the HG and the UG, will be performed at this time using double blinding.

At this stage, the surgeon will be blinded to group allocation and clinical assessment and will perform surgical planning for both uncemented and hybrid procedures using Peekmed software (Peekmed Inc, Braga, Portugal). Peekmed is a highly sensitive tool currently in use that focuses on digital surgical planning to evaluate the accuracy of corrections and to reproduce patient-specific anatomy. Data from both surgical plans will be extracted by the same surgeon using a specially designed digital form (Multimedia Appendices 2 and 3). Reports of the surgical plans will be printed and kept until surgery; however, only the correct plan, as decided by the random group allocation, will be provided to the surgeon by the assistant researcher before surgery.

The inclusion and exclusion criteria are shown in Textbox 1.

Participants who wish to withdraw after the operation, as instructed in the preparticipation recommendations, may continue with usual treatment at the hospital. In the case of withdrawal at any point after surgery, the data will be considered missing, and data imputation techniques will be evaluated. Data from participants who discontinue the study will remain available in the electronic dataset during revision and will be presented in the results. The study will follow the Consolidated Standards of Reporting Trials (CONSORT) flow chart and tables.

Participants will be randomized and allocated to 2 different groups. On the day the participant signs the written consent form, each participant will receive a unique identification number that will be randomized later. Randomization will be performed in 10 random blocks of 12 participants each using Randomized.org. A computer-generated list will assign participants to either (i) the HG or (ii) the UG. An assistant researcher who is not involved in other study roles will carry out this allocation process. Data related to the randomization list will be kept confidential by the researcher in charge of the randomization. Consequently, both the researcher responsible for outcome evaluations and the participants will be blinded to group allocation.

Before surgery, the surgeon will be blinded to group allocation and will generate radiographic measurements and surgical planning for both uncemented and hybrid surgeries for each patient. All participants will be blinded to the technique utilized. However, a record for medical use will be available, upon request, in the hospital medical file. The surgeon cannot be blinded during the surgical procedure because this is a clinical trial of surgical treatment techniques. To minimize observer bias, all postoperative clinical and functional evaluations will be performed by independent researchers blinded to participant group allocation and postoperative radiographs. Postoperative radiographs will be analyzed by a separate researcher with experience in hip surgery, who will be blinded to preoperative measurements, surgical planning, and postoperative clinical and functional evaluations.

Therefore, blinding was applied in all 3 stages and across all 3 levels, which is known as triple-blinding. The surgeon is blinded to the preoperative evaluation and performs surgical planning without knowledge of which implant will be used. Blinding is broken at the time of surgery. Participants remain blinded throughout the study. Two types of evaluators are involved: an imaging evaluator and a clinical evaluator. The postoperative evaluator, using the X-ray, is blinded to the preoperative evaluators and the postoperative clinical evaluation. The postoperative clinical evaluator is blinded to both group evaluation and radiographic examination. A description of each researcher involved in the study is provided below in Table 1.

In both groups, early active motion of the operated limb will be permitted as soon as motor function recovers from anesthesia. All participants will be instructed to begin immediate knee flexion and extension exercises, ankle and foot movements, and active calf pump exercises. No orthotic devices or physical positional measures will be utilized to restrict hip motion. However, all patients will be advised to avoid flexion, adduction, and internal rotation of the operated hip, or sitting in low chairs for at least 3 months. Walking with 2 crutches with weight-bearing as tolerated will be stimulated on the first postoperative day until the follow-up visit at 21 days, and patients will be discharged for ambulatory care as soon as ambulation is possible with comfort. Sports and activities on extreme hip motions will be discouraged for at least 3 months.

The primary outcomes of this study will be patient-reported function and complications.

Clinical evaluation will comprise the measurement of hip ROM to assess joint mobility, and the HHS questionnaire will be applied to assess function. Hip ROM will be measured using the goniometer, with the patient lying supine, to determine joint mobility. Hip function will be assessed using the HHS, which is a THA-specific questionnaire composed of patient-reported function and physician-assessed joint ROM, including pain, function, deformity, and mobility assessment [19,20]. The HHS is scored up to 100 points, where each section has a different score, and after applying the questionnaire, all scores are summed up. Scores below 70 are considered low, scores between 70 and 80 are considered fair, scores between 80 and 90 are considered good, and scores between 90 and 100 are considered excellent [19].

The incidence of complications (during and after surgery) will be extracted from an intraoperative questionnaire completed by the surgeon, an immediate postoperative questionnaire reported by the patient, and a special severe adverse effect questionnaire, which will be filled whenever the patient requires readmission or additional surgery.

Secondary outcomes will include comparisons of QoL, joint mobility, function, satisfaction, and pain before and after the surgery, as well as radiographic parameters extracted from the immediate postoperative radiograph. The annual frequency of revision surgeries will be recorded.

QoL will be evaluated using 12-Item Short Form Health Survey version 2 questionnaire [21]. QoL is defined as an individual’s perception of their position in life in the context of the culture and value systems in which they live and about their goals, expectations, standards, and concerns [21]. The 12-Item Short Form Health Survey is an instrument for measuring QoL composed of 12 items that assess eight different dimensions of influence on QoL, considering the individual’s perception of aspects of their health in the last 4 weeks [21]. Each dimension’s score is summed up, and the final score can be between 0 and 100; the higher the score, the better the QoL [22].

Participant satisfaction assessment will be measured using a 10-point numerical rating scale ranging from 1 (very dissatisfied) to 10 (completely satisfied) [23].

Other aspects of health, such as pain, will be evaluated through the Visual Analog Scale. The Visual Analog Scale provides a simple and efficient measure of pain intensity and is used when a fast pain index that can be assigned to a numerical value is needed [24].

Radiographic parameters will include the ability to restore anatomical normality parameters on postoperative radiographs according to the surgical plan (namely the limb length discrepancy, the horizontal off-set of the hip, difference between the back of the prosthesis and the tip of the trochanter, inclination of the acetabular component, and the difference between offset obtained to the normal side) all of this using the Peekmed surgical planning software.

The annual frequency of revision surgery will be observed starting from 1 year after surgery and annually until 5 years, and up to 10 years.

All questionnaires will be administered by examiners blinded to the surgical procedure. Questionnaires will be completed using digital devices (computer or tablet).

Participant data will be collected using study forms (Multimedia Appendices 1-4) and stored on a designated Google Drive, which will be used as the study repository. A copy of all the files will be stored on an external hard drive for backup. The research supervisor will audit completion of the electronic spreadsheet and will be responsible for data safety and accuracy. Incorrect or missing data will be assessed by this researcher, who will not be involved in other tasks in the study, and corrected when necessary. Data from participants who discontinue the study will remain available in Google Drive for the reviewers and will be presented in the results, CONSORT flowchart, and tables. Study data will be stored for at least 5 years after completion of the study.

The level of pragmatism is shown in Figure 2 and detailed in Table 2.

The sample size was calculated using the Statulator Sample Size Calculation tool [25]. To disprove the null hypothesis of equality, assuming a pooled SD of 10.5 units for the HHS [6], the study would require a sample size of 60 participants per each group (ie, a total sample size of 120 for equal group sizes) to achieve a power of 80% and a significance level of .05 (2-sided) for detecting a true difference in means of 5.39 units between the test and the reference groups (ie, 56.9 vs 62.3).

Results will be presented descriptively, with continuous data expressed as means (SD) and medians, and categorical data will be presented as means or percentages. For inferential analysis, the normality of the variables will be assessed using the Kolmogorov-Smirnov test. Dichotomous variables will be analyzed using the Fisher exact test and chi-square test, and continuous variables will be analyzed using the t test. Demographic data will be analyzed using ANOVA test, and the chi-square test will be used for the categorical data. In cases of non-normal distribution, appropriate nonparametric tests will be used according to the nature of the variable.

Primary outcomes, complications, and reoperations will be analyzed at 48 weeks. Paired and subgroup analyses are foreseen between periods of 3, 6, 24, and 48 weeks for the described outcomes. Results will be reported with 95% CI.

All statistical tests will be 2-sided, with a significance level of P=.05. Data will be analyzed using the Online Statistics Calculator, DATAtab/Numiqo (2025) [26]. Data from participants who receive additional treatments (eg, revision surgery for fractures) during study participation will be retained for intention-to-treat analysis.

This study was approved by the Institutional Review Board of the Faculty of Medical and Health Sciences of Juiz de Fora–Suprema (CAAE: 82413124.4.0000.5103). Any important protocol modifications will be communicated to the ethics committee. Study results will be communicated through the paper publication and will be explained to participants who wish to know their individual results. No compensation will be provided to any participant. All digital records will be stored on a private, password-protected Google Drive. Access to each specific folder will be granted only to the researchers to the extent of their participation. Only the study supervisor will be granted full access to the whole database during the study. Participants must sign a written informed consent form before they are invited for a consultation.

In Brazil, up to 75% of the population relies exclusively on the public health system (Sistema Único de Saúde [SUS]). From 2008 to 2015, 166,365 total hip replacements were performed only in SUS [27]. After 2012, the number of uncemented and hybrid constructs surpassed the cemented replacements in Brazil [19].

Designed as a universal, integral, and equitable system, SUS should consider the cost-effectiveness of the treatments provided [27]. While total hip replacement has been proven cost-effective in many countries around the world [28], such studies were carried out using data from implants that are either unavailable in Brazil or are much more expensive due to importation fees and taxes. Therefore, although modern national implants have become available and good clinical outcomes have been reported in some studies [15-17]here are no level 1 studies currently available, to date, comparing such implants. Additionally, this study introduces an innovation by being the first to use Peekmed, an artificial intelligence–based preoperative planning software for orthopedic surgery.

Besides clinical information as to whether the Brazilian population should have better outcomes using hybrid or uncemented total hip replacement, the conclusion of this study may also be instrumental for future economic studies applicable to SUS and the private health sector in Brazil.

This study is expected to have several limitations: the fact that it was conducted in one hospital and by one surgeon may raise questions about external validity and reproducibility in other scenarios. On the other hand, this feature provides better homogeneity, increases internal validity, and consistency of results. To minimize this external validity limitation, we used a pragmatic approach to mitigate the potential bias of a very controlled setting. Another potential conflict is that the company that makes the implants provided them at a discount rate and gave equipment to the study team. Even though it is called an “unrestricted agreement,” this still creates a risk of potential conflict of interest because the results could benefit that company. The researchers received no personal benefits, salaries, or incentives, which is relevant for this subject. Additionally, each extract of information was collected independently by the researchers, and the complete database was only accessible to one independent data curator (the research supervisor), who was only responsible for that task and had no role in data collection. An additional measure to reduce bias was the use of implants from the same manufacturer, thereby minimizing the risk of conflict of interest in the comparison between implants. Nevertheless, a potential influence on the overall results cannot be entirely excluded, as a purchase discount was applied. The blinding of the surgeon, the evaluators, and the patients in different stages of the study also reinforces the commitment to diminish biases and increase the independence of the results.

This study is a prospective, randomized, pragmatic clinical trial that uses blinding to evaluate national implants for both hybrid arthroplasty and uncemented arthroplasty. It is the first study with adequate power to prospectively evaluate the outcomes of each surgical procedure in Brazil. Successful completion of this study may provide clinical evidence on the performance of national implants, as well as showing the preferred implant construct (hybrid or uncemented), if any, for hip replacement in Brazil.