Implementation of outpatient hip and knee arthroplasty in a multicenter public healthcare setting.

BACKGROUND AND PURPOSE: Length of hospital stay after hip and knee arthroplasty is about 1 day in Denmark with few patients discharged on the day of surgery. Hence, a protocol for multicenter implementation of discharge on day of surgery has been instituted. We aimed to describe the implementation of outpatient hip and knee arthroplasty in a multicenter public healthcare setting. METHODS: We performed a prospective multicenter study from 7 public hospitals across Denmark. Patients were screened using well-defined in- and exclusion criteria and were discharged on day of surgery when fulfilling functional discharge criteria. The study period was from September 2022 to February 2023 with variable start of implementation. Data from the same centers in a 6-month period before the COVID pandemic from July 2019 to December 2019 was used for baseline control. RESULTS: Of 2,756 primary hip and knee arthroplasties, 37% (95% confidence interval [CI] 35-39) were eligible (range 21-50% in centers) and 52% (range 24-62%) of these were discharged on day of surgery. 21% (CI 20-23) of all patients (eligible and non-eligible) were discharged on day of surgery with a range of 10-31% within centers. This was an additional 15% (CI 13-17, P < 0.001) compared with patients discharged in the control period (6% in 2019). CONCLUSION: We found it possible to perform outpatient hip and knee replacement in 21% of patients in a public healthcare setting, probably to be increased with further center experience.

Mini-Navigation Utilization in THA Results in Shorter Length of Stay, Increased Home Discharge, and Higher Physical Therapy Mobilization Scores Compared to THA Without Navigation.

BACKGROUND: As volume of total hip arthroplasty (THA) continues to increase, the utilization and availability of in-traoperative advanced technologies to arthroplasty surgeons continues to rise as well. Our primary goal was to determine whether the use of a mini navigation technology extended operative times and secondarily if it affected postoperative outcomes following elective THA. METHODS: A single-institution total joint arthroplasty da-tabase was utilized to identify adult patients who underwent elective THA from 2017 to 2019. Baseline demographic data along with surgical operative time, length of stay (LOS) and discharge disposition were collected. The Activity Measure for Post-Acute Care (AM-PAC) was used to determine physi-cal therapy progress. RESULTS: A total of 1,162 THAs were performed of which 69.1% (803) used navigation while 30.9% (359) did not. Baseline demographics including age, sex, body mass index (BMI), insurance, and smoking status were not statistically different between groups. The operative time was shorter in the navigation group compared to THA without navigation (115.1 vs. 118.9 min, p < 0.0001). Mean LOS was signifi-cantly shorter in the navigation THA group as compared to THA without navigation (2.1 vs. 2.6 days, p < 0.0001). Postoperative AM-PAC scores were higher in the navigation group on postoperative day 1 as compared to patients with-out navigation (18.87 vs. 17.52, p < 0.0001). Additionally, a greater percentage of patients were discharged directly home after THA with navigation as compared to THA without navigation (89.54% vs. 83.57%, p < 0.0001). CONCLUSION: Our study demonstrates that hip navigation technology in the setting of THA is associated with reduced operative times and higher AM-PAC mobilization scores. Hip mini navigation technology shortens operative times while improving early patient outcome scores in association with shorter LOS and greater home-based discharge.

Outcomes in Arthroplasty Procedures Performed for Femoral Neck Fractures Does Approach Affect Outcome?

BACKGROUND: The surgical approach used for arthroplasty in the setting of hip fracture has traditionally been decided based on surgeon preference. This study analyzed the ef-fect of the surgical approach on hospital quality measures, complications, and mortality in patients treated with hip arthroplasty for fracture fixation. METHODS: A cohort of consecutive acute hip fracture pa-tients who were 60 years of age or older and who underwent hemiarthroplasty (HA) or total hip arthroplasty (THA) at one academic medical center between January 2014 and January 2018 was included. Patient demographics, length of stay (LOS), surgery details, complications, ambulation at dis-charge, discharge location, readmission, and mortality were recorded. Two cohorts were included based on the surgical approach: the anterior-based cohort included the direct an-terior and anterolateral approaches and the posterior-based cohort included direct lateral and posterior approaches. RESULTS: Two hundred five patients were included: 146 underwent HA (81 anterior-based and 65 posterior-based) and 79 underwent THA (37 anterior-based and 42 posterior-based). The mean age of the HA and THA cohorts was 84.1 ± 7.5 and 73.7 ± 8.0 years, respectively. There was no dif-ference in LOS, time to surgery, or surgical time between the two cohorts for HA and THA. There were no differences in perioperative complications, including dislocation, ob-served based on surgical approach. No difference was found between readmission rates and mortality. CONCLUSION: In this cohort of hip fracture arthroplasty patients, there was no difference observed in hospital quality measures, readmission, or mortality in patients based on sur-gical approach. These results are in contrast with literature in elective arthroplasty patients supporting the use of an anterior approach for potential improved short-term outcomes.

Conversion Total Hip Arthroplasty in Patients With Osteopetrosis: Insights From Two Unique Cases.

CASE: Two patients with osteopetrosis underwent conversion total hip arthroplasty (THA) after failure of internal fixation due to hip fractures. We experienced challenges, including difficulty of hardware removal, remaining of previous broken screws in the canal, difficulty in finding the femoral canal, and an intraoperative acetabulum fracture. Despite complications, both patients achieved satisfactory functional outcome after surgery at the latest follow-up. CONCLUSION: Our cases showed that previous hip fracture and failed internal fixation make conversion THA more complex and unpredictable in patients with osteopetrosis. This in turn underscores the critical need for advanced preoperative planning, intraoperative flexibility, and meticulous postoperative care.

A complementary analytical tool for hip prosthesis dislocation: Thermal imaging in rehabilitation.

The use of routine ionizing imaging in identify and classify patients with dislocation or infection after surgery has some medical contraindication, in addition to risks associated with the ionizing load and elevated costs. A novel, less expensive and non-ionizing imaging technique, called infrared thermal imaging, can be proposed as a complementary method to routinely evaluate hip prosthesis patients and track their inflammation response following serious complications. Here we report a case of a total hip prosthesis which was dislocated during inpatient rehabilitation, and ultimately reduced without surgical procedure. During the process, routine clinical and radiographic diagnosis was complemented with an infrared examination. The infrared images were easy to take bedside, without direct contact with the area of surgery, and well tolerated. After the dislocation reduction, the thermal imaging procedure provided important feedbacks on the local inflammation, helping to exclude other complications such as the infections.

Accuracy of cup placement compared with preoperative surgeon targets in primary total hip arthroplasty using standard instrumentation and techniques: a global, multicenter study.

BACKGROUND: Acetabular cup positioning in total hip arthroplasty (THA) is closely related to outcomes. The literature has suggested cup parameters defined by the Lewinnek safe zone; however, the validity of such measures is in question. Several studies have raised concerns about the benefits of using the Lewinnek safe zone as a predictor of success. In this study we elected to use prospective surgeon targets as the basis for comparison to see how successful surgeons are positioning their cup using standard instruments and techniques. METHODS: A prospective, global, multicenter study was conducted. Cup positioning success was defined as a composite endpoint. Both cup inclination and version needed to be within 10° of the surgeon target to be considered a success. Radiographic analysis was conducted by a third-party reviewer. RESULTS: In 170 subjects, inclination, target versus actual, was 44.8° [standard deviation (SD 0.9°)] and 43.1° (SD 7.6°), respectively (p = 0.0029). Inclination was considered successful in 84.1% of cases. Mean version, target versus actual, was 19.4° (SD 3.9°) and 27.2° (SD 5.6°), respectively (p < 0.0001). Version was considered successful in 63.4% of cases, and combined position (inclination and version) was considered successful in 53.1%. CONCLUSION: This study shows that with traditional methods of placing the cup intraoperatively, surgeons are only accurate 53.1% of the time compared with a predicted preoperative plan. This study suggests that the inconsistency in cup positioning based on the surgeon's planned target is potentially another important variable to consider while using a mechanical guide or in freehand techniques for cup placement in THA. TRIAL REGISTRATION: This study is registered on ClinicalTrials.gov, NCT03189303.

Autologous concentrated bone marrow injection for precollapse osteonecrosis of the femoral head concurrent with contralateral total hip arthroplasty: protocol for a clinical trial.

INTRODUCTION: The femoral head contralateral to the collapsed femoral head requiring total hip arthroplasty (THA) often manifests in the precollapse stage of osteonecrosis of the femoral head (ONFH). It is not yet demonstrated how autologous concentrated bone marrow injection may prevent collapse of the femoral head concurrent with contralateral THA. The primary objective is to evaluate the efficacy of autologous concentrated bone marrow injection for the contralateral, non-collapsed, femoral head in patients with bilateral ONFH, with the ipsilateral collapsed femoral head undergoing THA. METHODS AND ANALYSIS: This is a multicentre, prospective, non-randomised, historical-data controlled study. We will recruit patients with ONFH who are scheduled for THA and possess a non-collapsed contralateral femoral head. Autologous bone marrow will be collected using a point-of-care device. After concentration, the bone marrow will be injected into the non-collapsed femoral head following the completion of THA in the contralateral hip. The primary outcome is the percentage of femoral head collapse evaluated by an independent data monitoring committee using plain X-rays in two directions 2 years after autologous concentrated bone marrow injection. Postinjection safety, adverse events, pain and hip function will also be assessed. The patients will be evaluated preoperatively, and at 6 months, 1 year and 2 years postoperatively. ETHICS AND DISSEMINATION: This protocol has been approved by the Certified Committee for Regenerative Medicine of Tokyo Medical and Dental University and Japan's Ministry of Healthy, Labour and Welfare and will be performed as a class III regenerative medicine protocol, in accordance with Japan's Act on the Safety of Regenerative Medicine. The results of this study will be submitted to a peer-review journal for publication. The results of this study are expected to provide evidence to support the inclusion of autologous concentrated bone marrow injections in the non-collapsed femoral head in Japan's national insurance coverage. TRIAL REGISTRATION NUMBER: jRCTc032200229.

Basicervical femoral neck fractures: an observational study derived from the Swedish Fracture Register.

BACKGROUND AND PURPOSE: Limited research has been conducted on basicervical femoral neck fractures (bFNFs). The importance of displacement in clinical outcomes remains unclear. We aimed to characterize patient demographics, degree of displacement, treatment, treatment failures, and reoperations in a cohort of fractures from the Swedish Fracture Register (SFR). METHODS: 1,260 fractures in 1,185 individuals ≥ 60 years who had a bFNF registered in the SFR at 6 orthopedic departments from 2011 to 2020 were screened through radiographic review. The final sample included 291 patients with a confirmed bFNF. The medical records of these 291 patients were reviewed. We assessed baseline characteristics, initial fracture dislocation, treatment methods, tip-apex distance, failures, reoperations, and mortality. RESULTS: The mean age was 82 years (range 60-101, 55% women). 98 (34%) were undisplaced and 193 (66%) displaced. All patients underwent operative treatment. In the undisplaced group 95 (97%) patients received internal fixation (IF) and 3 (3%) had primary hip arthroplasty. In the displaced group 149 (77%) received IF and 41 (21%) had primary hip arthroplasty. 33 (11%) suffered treatment failure. When treating an undisplaced bFNF with IF, only 3 (3%) experienced treatment failure, in contrast to the 24 (16%) failure rate for a displaced bFNF. CONCLUSION: Undisplaced bFNFs have a low failure rate when treated with IF. For displaced bFNF treated with IF the failure rate is considerably higher. There is a need for further investigation of classification, treatment, and outcome of bFNF.

[Application of modified acetabular anteversion and inclination angles test system in patients undergoing total hip arthroplasty after lumbar fusion].

Objective: To investigate the accuracy and effectiveness of acetabular cup placement in total hip arthroplasty (THA) after lumbar fusion applying of modified acetabular anteversion and inclination angles test system. Methods: A clinical data of 45 patients undergoing THA for osteoarthritis between January 2018 and June 2023 was retrospectively analyzed. All patients had previously received lumbar fusion. The modified acetabular anteversion and inclination angle test system was used in 26 cases (observation group) and not used in 19 cases (control group) during THA. There was no significant difference in baseline data such as gender, age, body mass index, operative side, number of lumbar fusion segments, and preoperative Harris score between the two groups ( P>0.05). The position of acetabular prosthesis, hip function (Harris score), and incidence of complications were compared between the two groups. Results: In the observation group, all acetabular cups were in the safe zone (anteversion angle, 25°-30°) during operation, and 1 acetabular cup (3.85%) was not in the safe zone after operation. In the control group, 9 acetabular cups (47.37%) were not in the safe zone. The postoperative difference between the two groups was significant ( P<0.05). There was no significant difference between intra- and post-operative acetabular inclination angles in the observation group ( P>0.05), and the postoperative acetabular inclination angle was significantly smaller in the observation group than in the control group ( P<0.05). All incisions healed by first intention and no infection occurred. All patients were followed up 6 months. There was no significant difference in Harris score between the two groups at different time point ( P>0.05), and there were significant differences between different time points in the two groups ( P<0.05). No joint dislocation occurred in the observation group during follow-up, while dislocation occurred in 2 cases and femoral impingement syndrome occurred in 1 case of the control group. There was no significant difference in the incidence of complications between the two groups ( P>0.05). Conclusion: For THA patients with lumbar fusion, the ideal placement angle of the acetabular cup can be obtained by using the modified acetabular anteversion and inclination angles test system during operation.

[Advances in study of surgical approaches and MRI evaluation of total hip arthroplasty].

Objective: To review the research on different surgical approaches and MRI evaluation of total hip arthroplasty (THA), to clarify the possible muscle damage caused by different approaches, and to help clinicians avoid intraoperative muscle damage and identify the causes of certain muscle-related complications after operation. Methods: The research literature on different surgical approaches and MRI evaluation of THA at home and abroad was extensively reviewed to summarize the MRI performance of the posterior approach, modified direct lateral approach, direct anterior approach, and minimally invasive anterolateral approach (also called Orthopadische Chirurgie Munchen approach). Results: The traditional posterior approach mainly damages the short external rotator muscle group and increases the incidence of postoperative dislocation; the piriformis-keeping posterior approach significantly improves the quality of the pyriformis tendon in the postoperative period, but it may lead to damage to the intrapelvic portion of the piriformis muscle. The modified direct lateral approach mainly damages the gluteus medius muscle, which increases the risk of postoperative claudication. The direct anterior approach mainly damages the vastus tensoris muscle and may result in damage to the short external rotator muscle group and the muscles around the incision. The minimally invasive anterolateral approach primarily damages the superior gluteal nerve, which subsequently leads to denervation of the broad fascial tensor fasciae latae, and this approach may also result in injury to the gluteus medius and gluteus minimus muscles. The muscle damage status significantly affects prognosis, and the minimally invasive approach is more suitable for elderly patients. Conclusion: MRI can clarify the different types of muscle damage caused by different surgical approaches. Minimally invasive approaches can reduce muscle damage and improve postoperative function compared with traditional approaches, and can benefit elderly patients more, but due to the small field, forcing to expand the surgical field will lead to unintended muscle damage and reduce postoperative function.

Language-adaptive artificial intelligence: assessing CHATGPT'S answer to frequently asked questions on total hip arthroplasty questions.

ChatGPT is reported to be an acceptable tool to answer a majority of frequently asked patient questions. ChatGPT also converses in other languages including Urdu, which offers immense potential for the education of Pakistani patients. Therefore, this study evaluated ChatGPT's Urdu answers to the ten most frequently asked questions on Total Hip Arthroplasty, which were then rated by an expert. Out of 10 answers in English, 9 (90%) were satisfactory requiring minimal clarification and 1 (10%) was satisfactory requiring moderate clarification. In both Roman and Nastaliq script Urdu, 1 (10%) answer was satisfactory requiring moderate clarification, while 9 (90%) were unsatisfactory requiring substantial clarification. In conclusion, as opposed to ChatGPT English responses, Urdu responses were much less rigorous, generic, and lacked scientific rigor. We have a long way to go before Pakistani patients with limited English language skills could benefit from AI chatbots like ChatGPT.

Comparison of fascia iliaca block with quadratus lumborum block for hip arthroplasty: A meta-analysis of randomized controlled trials.

BACKGROUND: The efficacy of fascia iliaca block (FIB) versus quadratus lumborum block (QLB) remains controversial for pain management of hip arthroplasty. We conduct a systematic review and meta-analysis to explore the influence of FIB versus QLB on the postoperative pain intensity of hip arthroplasty. METHODS: We have searched PubMed, EMbase, Web of Science, EBSCO, and Cochrane Library databases through July 2023 for randomized controlled trials assessing the effect of FIB versus QLB on pain control of hip arthroplasty. This meta-analysis is performed using the random-effect model or fixed-effect model based on the heterogeneity. RESULTS: Four randomized controlled trials and 234 patients were included in the meta-analysis. Overall, compared with QLB for hip arthroscopy, FIB was associated with substantially lower pain scores at 2 hours (mean difference [MD] = -0.49; 95% CI = -0.63 to -0.35; P < .00001) and pain scores at 12 hours (MD = -0.81; 95% CI = -1.36 to -0.26; P = .004), but showed no impact on pain scores at 24 hours (MD = -0.21; 95% CI = -0.57 to 0.15; P = .25), time to first rescue analgesia (standard mean difference = 0.70; 95% CI = -0.59 to 1.99; P = .29), analgesic consumption (MD = -4.80; 95% CI = -16.57 to 6.97; P = .42), or nausea and vomiting (odd ratio = 0.66; 95% CI = 0.32-1.35; P = .25). CONCLUSIONS: FIB may be better than QLB for pain control after hip arthroplasty, as evidenced by the lower pain scores at 2 and 24 hours.

Assessment of Automated Identification of Phases in Videos of Total Hip Arthroplasty Using Deep Learning Techniques.

Background: As the population ages, the rates of hip diseases and fragility fractures are increasing, making total hip arthroplasty (THA) one of the best methods for treating elderly patients. With the increasing number of THA surgeries and diverse surgical methods, there is a need for standard evaluation protocols. This study aimed to use deep learning algorithms to classify THA videos and evaluate the accuracy of the labelling of these videos. Methods: In our study, we manually annotated 7 phases in THA, including skin incision, broaching, exposure of acetabulum, acetabular reaming, acetabular cup positioning, femoral stem insertion, and skin closure. Within each phase, a second trained annotator marked the beginning and end of instrument usages, such as the skin blade, forceps, Bovie, suction device, suture material, retractor, rasp, femoral stem, acetabular reamer, head trial, and real head. Results: In our study, we utilized YOLOv3 to collect 540 operating images of THA procedures and create a scene annotation model. The results of our study showed relatively high accuracy in the clear classification of surgical techniques such as skin incision and closure, broaching, acetabular reaming, and femoral stem insertion, with a mean average precision (mAP) of 0.75 or higher. Most of the equipment showed good accuracy of mAP 0.7 or higher, except for the suction device, suture material, and retractor. Conclusions: Scene annotation for the instrument and phases in THA using deep learning techniques may provide potentially useful tools for subsequent documentation, assessment of skills, and feedback.

Rapid Return to Braking After Anterior and Posterior Approach Total Hip Arthroplasty.

BACKGROUND: Little is known about the effect of surgical approach on return to braking after total hip arthroplasty (THA), and few studies have investigated braking after THA with modern surgical techniques and rehabilitation protocols. METHODS: In a prospective comparative design, we enrolled 65 patients who received right-sided primary THA at our institution from April 2018 through March 2020, 34 with a direct anterior approach (DAA) and 31 with a posterior approach (PA). Braking tests measuring brake reaction time (BRT) and brake pedal depression (BPD) were administered to patients preoperatively and at 1, 2, and 4 weeks postoperatively using a realistic driving simulator. BRT and BPD were compared between groups and preoperatively versus postoperatively using mixed-effects models. RESULTS: Preoperative BRT averaged 638 msec in the DAA group and 604 msec in the PA group (P = 0.31). At 1 week postoperatively, the DAA group had significantly prolonged BRT compared with preoperatively (694 msec, P = 0.02). No significant difference was observed in the PA group (633 msec, P = 0.31). Both groups had returned to baseline by 2 weeks, and both had significantly faster BRT at 4 weeks compared with preoperatively (583 msec for DAA, P = 0.01; 537 msec for PA, P < 0.001). BPD was similar between groups, and there were no significant differences between preoperative and postoperative BPD at any time point. CONCLUSIONS: With modern surgical techniques, BRT after right-sided THA returns to baseline levels approximately 2 weeks after surgery. There seems to be a quicker return to preoperative BRT observed in patients with a PA.

Mid-term results of cemented hip arthroplasties through the direct anterior approach in the lateral decubitus position: a retrospective cohort study.

BACKGROUND: Reports show a high complication rate when starting with the Direct Anterior Approach (DAA) in a supine position for hip arthroplasty. The DAA with the patient in lateral decubitus position may avoid this problem because it supposedly provides better visibility, especially on the femoral side. However, this approach did show a rather high complication rate during the adoption of the approach at 1 year follow up in our previous report. We were interested what the overall 7 year survival estimate would be and whether improvement could be seen with growing experience. METHODS: A cohort of patients undergoing total hip arthroplasty right from the start of applying the DAA in lateral decubitus position was analysed. RESULTS: In total 175 hip prostheses (162 patients) were evaluated. The 7-year survival estimate was 95.1%, 95 CI: 91.8-98.4%. In 6 of 8 revisions there was aseptic loosening of the stem. By dividing the cohort into 3 consecutive groups in time we did not see a significantly improving revision rate. CONCLUSIONS: In our experience, the adoption of the direct anterior approach in lateral decubitus position caused a relatively low 7-year survival estimate without an apparent decrease with growing experience, however given the low number of cases further research is needed to investigate the long-term risk of adopting a new approach.

[Estimation of acetabular cup prosthesis coverage rate in total hip arthroplasty based on X-ray films].

Objective: To explore the method of accurately estimating the acetabular cup prosthesis coverage rate (hereinafter referred to as "cup coverage rate") in total hip arthroplasty (THA) based on X-ray films, and to determine the effective parameters that can be used to estimate the cup coverage rate. Methods: The three-dimensional printed pelvic models were established based on CT data of 16 healthy pelvis, and the acetabular prosthesis were implanted according to conventional THA procedure. The length and width of the uncovered area of the acetabular cup prosthesis were measured by a modified X-ray recording method with a rotating C-arm X-ray machine, and the cup coverage rate was calculated. Then the differences among the traditional anteroposterior X-ray recording method, the modified method, and actual measurement on pelvic model were statistically analyzed. The correlation between the area of the uncovered area of the prosthesis and its width and length was analyzed by using multiple linear regression analysis. Results: The cup coverage rates of traditional method, modified method, and actual measurement were 78.22%±3.36%, 86.74%±3.61%, and 89.62%±2.62%, respectively, with significant differences ( P<0.05). The results of multiple linear regression analysis showed that the width and length were positively linear with the uncovered area of the prosthesis, and the regression equation was as follows: uncovered area of the prosthesis=-21.192+0.248×width+0.140×length, and the coefficient of determination R 2=0.857, P<0.001. Conclusion: Compared with the traditional method, the modified method can more accurately evaluate the cup coverage rate during THA, and the width of the uncovered area of the prosthesis can be used as an effective reference for the cup coverage rate.

Billing rules / global period affect postoperative follow-up practices following total hip arthroplasty.

BACKGROUND: Total hip arthroplasty (THA) is a common procedure following which postoperative visits are important to optimize outcomes. The associated global billing period includes the 90 postoperative days (or approximately 13 weeks), during which professional billing is included with the surgery itself. The current study assessed clinical practice patterns relative to the global billing period. METHODS: Using the PearlDiver M91Ortho dataset, the incidence and timing of Evaluation and Management (E&M) codes in the 26 weeks following THA were assessed. The follow-up visits within and beyond the global billing period, and those conducted by surgeons versus non-surgeon advanced practice providers (APPs) were determined. RESULTS: 77,843 THAs were identified. Follow-up visits peaked at postoperative weeks 3, 7, and 14. The greatest week-to-week variation in the number of follow-ups was from weeks 13 to 14 immediately following the global billing period (representing a greater than 4-fold increase in visits.) During the first 13 postop weeks, 73.8% of patients were seen by orthopedic surgeons (as opposed to APPs). In the following 13 weeks, a significantly greater percentage of visits were with surgeons (86.8%, p<0.0001). CONCLUSIONS: Following the THA global billing period, there was marked increase in the number of follow-ups and transition to a greater percentage being performed by the surgeons. These results provide interesting insight into the potential impact of the billing structure on how practice is pursued.

Sex-based differences in neck selectivity in total hip arthroplasty using a modular femoral neck system.

BACKGROUND: Dislocation is a major complication of total hip arthroplasty (THA). The modular femoral neck system provides practical advantages by allowing adjustment of neck version and length in the presence of intraoperative instability. Anatomical studies have identified morphological differences in the hip joint between men and women. Despite sex-based differences in hip morphology, it remains unclear whether such differences affect neck selectivity in THA using a modular neck system and whether this approach achieves anatomical reconstruction, thereby reducing complications such as dislocation. This study aimed to investigate gender differences in neck selectivity in THA with the modular neck system and assess the clinical impact of the modular neck system. METHODS: A total of 163 THAs using a modular neck system were included in this study. Data on the type of modular neck and intraoperative range of motion (ROM) were retrieved from patient records. Pre- and post-operative leg length differences (LLD) were examined as part of the radiographic assessment. Dislocation was investigated as a postoperative complication. RESULTS: Neck selectivity did not significantly differ between men and women. The comparison of pre- and post-operative LLD revealed a tendency for varus necks to improve LLD more than version-controlled necks. Furthermore, no significant correlation was found between intraoperative ROM and neck selectivity, or postoperative dislocation and neck selectivity. CONCLUSIONS: This study on THA with a modular neck system provided valuable insights into sex-based differences in neck selectivity and highlighted the potential benefits of the modular neck system in addressing LLD and preventing postoperative dislocation.