How Much Benefit Can Robot-Assisted Total Hip Arthroplasty Provide for Patients with Severe Hip Dislocation? -a Propensity Score-Matched Analysis

How Much Benefit Can Robot-Assisted Total Hip Arthroplasty Provide for Patients with Severe Hip Dislocation? -a Propensity Score-Matched Analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article How Much Benefit Can Robot-Assisted Total Hip Arthroplasty Provide for Patients with Severe Hip Dislocation? -a Propensity Score-Matched Analysis Yu Zhang, Wentian Gao, Qiangqiang Li, Aikeremu Aierken, Yao Yao, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8512197/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Severe hip dislocation caused by various reasons poses significant challenges to total hip replacement(THA)surgery. The application value of robot-assisted THA in such diseases is still unclear. This propensity score-matched study aimed to compare the early outcomes of robot-assisted THA (RaTHA) versus manual THA (MTHA) in patients with severe hip dislocations (Crowe type III/IV). Patients and Methods Patients undergoing THA for severe dislocations were prospectively enrolled, and thier data were collected. Using propensity score matching (based on age, sex, BMI, Crowe classification, and comorbidities), patients were allocated into matched RaTHA and MTHA cohorts. The groups were compared at 12 months postoperatively regarding perioperative indicators, radiographic assessments, functional outcomes (Harris Hip Score, HHS), and complication rates. Results After matching, 29 MTHA and 33 RaTHA patients were finally analyzed. RaTHA was associated with a significantly longer operative time ( P = 0.042), longer preoperative length of stay (LOS)( P = 0.032), and higher hospitalization costs ( P = 0.008) compared to MTHA. Postoperative LOS was similar between the groups. Preoperative HHS were comparable, whereas the RaTHA group showed no significantly higher HHS at 12 months postoperatively ( P = 0.081). The variability in cup positioning (standard deviation) was lower in the RaTHA group for both inclination (4.7° vs. 8.1°) and anteversion (4.6° vs. 8.6°). However, no statistically significant differences were observed in mean cup inclination or anteversion angles, limb length discrepancy (LLD), or femoral and acetabular offset gaps ( P > 0.05). Regarding complications, two patients in the RaTHA group experienced dislocations at 3 or 4 months postoperatively, while six patients in the MTHA group had iatrogenic acetabular defects. Both groups reported two cases of postoperative symptoms of femoral nerve palsy. Conclusion For complex and anatomically variable bone structures, robotic technology offered an advantage in procedural consistency, effectively reducing the risk of excessive bone loss. Nevertheless, its impact on shortly functional outcomes, dislocation rates, and economic burden did not currently support a definitive recommendation for its widespread use. Level of evidence Level Ⅱ. Hip dislocation Total hip arthroplasty Robot-assisted Manual technique Figures Figure 1 Introduction Various reasons (such as congenital hip dysplasia and postoperative hip joint infection in childhood) leading to severe hip dislocation pose significant challenges for surgical treatment [ 1 , 2 ]. These include abnormal acetabular bony structures, such as shallow and small acetabula and shortened acetabular roofs, which compromise the acetabulum's ability to adequately cover the femoral head [ 3 – 5 ]. Additionally, the formation of pseudoacetabula resulting from chronic dislocation further complicates the surgical procedure by obscuring normal anatomical landmarks[ 6 ]. A narrow proximal medullary canal adds to the difficulty [ 7 – 9 ]. Moreover, patients often present with significant leg length discrepancy and associated muscle atrophy or deficiency [ 10 , 11 ], further increasing surgical complexity. This is particularly critical in cases with severe femoral head dislocation and muscle atrophy/loss subsequent to childhood hip osteotomy or suppurative hip arthritis.These anomalies collectively elevate surgical difficulty and contribute to a higher incidence of postoperative complications, including intraoperative acetabular or proximal femoral fractures, leg length discrepancy, hip dislocations, prolonged operative times with increased blood loss, and elevated infection risks [ 12 – 15 ]. Recent advancements in robot-assisted surgery have introduced new possibilities in the field of THA[ 16 , 17 ]. Robotic systems enable surgeons to perform individualized preoperative planning for complex hip arthroplasty, including prosthesis positioning and alignment, selection of prosthesis type, and control of leg length discrepancy and offset. Intraoperatively, robotic arms assist in precisely locating the true acetabulum and accurately positioning the acetabular cup, theoretically reducing the risk of prosthesis malalignment, wear and postoperative dislocation [ 18 , 19 ]. While robot-assisted THA has been widely applied in common hip pathologies, its potential benefits in severe hip dislocations remain relatively unexplored. The primary aim of this study was to compare the early functional recovery, assessed by the Harris Hip Score (HHS) at 12 months postoperatively, between RaTHA and MTHA in patients with severe hip dislocations (Crowe type III/IV). Secondary aims were to compare perioperative indicators (operative time, blood loss, length of stay, costs), radiographic outcomes (cup positioning, limb length discrepancy, offset), and complication rates. Through a propensity score-matched study, we seek to guide clinical practice by clarifying how robot-assisted surgery can benefit patients with severe hip dislocations, thereby enhancing the understanding and application of this emerging technology. Methods and Materials Study Design and Patients Recruitment This propensity score-matched study was approved by the institutional review board (2022-448-01). Patients aged 18-75 years diagnosed with severe hip joint dislocation (Crowe type Ⅲ or Ⅳ) were enrolled. All patients provided written informed consent. Exclusion criteria included neuromuscular dysfunction, hip infection, revision hip arthroplasty, and severe medical or surgical comorbidities. Patient allocation to the robot-assisted THA (RaTHA) group or manual (MTHA) group was as follows: 1. RaTHA Group (n=33): - Consecutive patients who voluntarily chose robotic-assisted surgery. - All procedures were performed by fellowship-trained arthroplasty surgeons using the MAKO robotic platform (MAKO 3.0, Stryker, USA). 2. MTHA Group (n=29): - Patients undergoing manual THA during the same period. - comprised exclusively of patients who declined robotic assistance due to personal preference or financial constraints, despite its availability. To minimize selection bias, propensity score matching was performed using nearest-neighbor matching (1:1) with a caliper width of 0.2 standard deviations, based on: - Demographic factors (age ±5 years, sex, BMI ±3 kg/m²) - Disease severity (Crowe classification III/IV, radiographic dislocation height) - Surgical year (within a 2-year window) Matching achieved excellent balance (all standardized mean differences <0.1). Both groups received identical implant systems and postoperative protocols. The CONSORT flow diagram. (Figure 1) Sample Size Consideration Given the rarity of severe hip dislocations (Crowe III/IV) requiring THA and the prospective nature of this study, a formal sample size calculation was not performed a priori. Instead, a feasibility approach was adopted, aiming to include all eligible patients presenting during the study period. Post-hoc power analysis indicated that the achieved sample size (n=62) provided 80% power to detect a moderate effect size (Cohen's d = 0.65) in the primary outcome (HHS at 12 months) with a two-sided α of 0.05. Surgical Procedures All THA procedures were performed under intravenous anesthesia combined with lumbar plexus nerve block, with patients in the supine position via an anterior approach. A 10 cm longitudinal incision was made 1.5 cm lateral to the line connecting the anterior superior iliac spine and the fibular head. After incising the deep fascia, the sartorius, rectus femoris, and tensor fascia latae muscles were retracted medially and laterally to expose the intermuscular interval. The superior branch of the lateral circumflex femoral vessels were ligated, and the anterior capsule was excised to expose the femoral head and neck. To improve surgical exposure and facilitate reduction, the tensor fasciae latae insertion at the iliac tuberosity was released. An initial femoral neck was performed, followed by removal of soft tissues such as the labrum, ligamentum teres remnant, and acetabulum fat pad. The joint capsule posterior to the greater trochanter was also released. Manual THA (MTHA) Group: Acetabular preparation was performed based on surgical experience of fellowship-trained arthroplasty surgeons. Sequential acetabular reamers of increasing sizes were used to ream the acetabulum concentrically, considering the femoral head size. Reaming was performed at 40° abduction and 10°-15° anteversion until the medial acetabular cortex was reached. The corresponding acetabular cup was then implanted at 40° abduction and 10°-15° anteversion, with supplemental screw fixation posterolaterally. The liner was subsequently placed. The lower limb was then extended, externally rotated, and adducted, and the proximal femur was elevated to expose the femoral osteotomy surface. Sequential femoral reamers were used to prepare the medullary canal until stability was achieved. The corresponding femoral stem was implanted, followed by selection and placement of an appropriate sized femoral head, and reduction was performed. Robot-assisted THA (RaTHA) Group : Preoperatively, three-dimensional hip models were from pelvic and proximal femoral CT data using robotic software. Based on acetabular anatomy of the affected and healthy sides, prosthesis size and positioning were planned at the true acetabulum, ensuring acetabular wall integrity and optimal prosthesis size. Femoral stem type was selected according to proximal femoral morphology and medullary canal dimensions. Three pins were inserted into the anterior superior iliac spine on the operative side to secure the pelvic reference array, and a registration screw was placed in a well-exposed bone anterior and superior to the acetabulum. After instrument calibration, acetabulum registration was performed by selecting well-exposed bony landmarks to minimize error. With robotic arm assistance, the acetabular bone bed was prepared according to the planned size and prosthesis model, and the corresponding acetabular prosthesis was implanted. Femoral preparation was identical to the MTHA group. Postoperative Treatments and Rehabilitation Protocols During the first month after surgery, the patient should primarily rest at home and avoid excessive activity to facilitate the healing of the extensively released soft tissues. Local anti-inflammatory, anti-edema, and analgesic treatments were applied to the incision. Concurrently, ankle pump exercise and range of motion training for non-hip joints were encouraged to reduce the risk of thrombosis and joint contracture. After one month, the patient should appropriately increase outdoor activities to exercise muscle strength in the affected limb and train coordination of walking gait and proprioception. In the event that the patient develops symptoms of femoral nerve palsy in the lower limbs postoperatively, neurotrophic therapy will be initiated, and a hip brace will be applied to maintain the hip in a flexed position, thereby alleviating symptoms associated with nerve traction. In cases where the patient undergoes proximal femoral osteotomy or intra-operative acetabular wall perforation occurs, a period of 3-month strict bed rest is mandated postoperatively. This protocol is implemented to facilitate bone union and ensure the stability of the prosthetic implant. Clinical and Radiographic Evaluation Baseline data including age, sex, hip dislocation severity (Crowe type Ⅲ or Ⅳ), BMI, limb length discrepancy (LLD), and preoperative HHS were collected and compared. Operative duration, intraoperative blood loss, transfusion rate, length of stay (LOS), and surgery-related complications were recorded and compared. Blood loss was calculated based on the difference in hemoglobin and hematocrit levels between preoperative and postoperative day 1. Radiographic evaluation (X-ray and CT) assessed acetabular cup abduction, anteversion angles, offset, LLD, and wall perforation[20]. Follow-up was conducted until 12 months after the surgery, during which the short-term joint function and the occurrence of surgery-related complications were observed and evaluated, including HHS, intraoperative acetabular wall perforation, postoperative prosthesis dislocation, wound infection, prosthesis loosening, and deep vein thrombosis. Statistical Analysis Data were analyzed using SPSS 28.0 (IBM, USA). continuous variables (age, BMI, HHS, blood loss, LOS, HC, cup angles) were tested for normality. Normally distributed data were expressed as mean ± standard deviation and compared using independent two-sample t-test. Skewed data (LLD, femoral and acetabular offset gaps) were expressed as medians (minimum, maximum) and analyzed using the Mann-Whitney U test. Complication rates were expressed as proportions and compared using the Chi-square test. A P -value < 0.05 was considered statistically significant. Results Baseline Clinical Characteristics Between January 2022 and June 2025, a total of 70 patients (74 hips) were enrolled in the clinical study. Of these, 34 patients (36 hips) underwent robotic-assisted surgery, while the remaining 36 patients (38 hips) received manual surgery. Following propensity score matching, four patients from the manual surgery group were excluded. Ultimately, after a postoperative follow-up period of 12 months, follow-up data were available for 33 patients (35 hips) in the robotic group and 29 patients (31 hips) in the manual group (Fig. 1 ). Baseline characteristics were well-balanced between the MTHA and RaTHA groups (Table 1 ). Mean age was similar (MTHA: 48.9 ± 10.2 years; RaTHA: 49.1 ± 14.1 years; P = 0.967). Sex distribution did not differ significantly, with males comprising 20.7% (6/29) in MTHA and 27.3% (9/33) in RaTHA ( P = 0.546). Operative side was balanced ( P = 0.988). Crowe type distribution was comparable (type III: 35.5% vs. 42.9%; type IV: 64.5% vs. 57.1%; P = 0.541). BMI values were similar (23.2 ± 3.0 vs. 23.6 ± 3.0; P = 0.652). Comorbidities, including prior surgical history (18.2% vs. 13.8%; P = 0.360) and hypertension (10.3% vs. 18.2%; P = 0.382), showed no significant differences, although hyperthyroidism was only reported in the MTHA group (6.9% vs. 0%). Overall, the groups were well-matched, minimizing confounding bias. Table 1 Baseline clinical characteristics. MTHA RaTHA P value age 48.9 ± 10.2 49.1 ± 14.1 0.967/(t=−0.041) Sex male(n/%) 6/20.7 9/27.3 0.546/(χ 2 =0.365) female(n/%) 23/79.3 24/72.7 Operative side left(n,%) 16/51.6 18/51.4 0.988/(χ 2 =0.000) right(n,%) 15/48.7 17/48.6 Crowe type Ⅲ 11/35.5 15/42.9 0.541/(χ 2 =0.374) Ⅳ 20/64.5 20/57.1 BMI 23.2 ± 3.0 23.6 ± 3.0 0.652/(t= 0.453) comorbitities history of surgical intervention 6/18.2 4/13.8 0.360/(χ 2 =0.838) hypertension(n/%) 3/10.3 6/18.2 0.382/(χ 2 =0.764) Hyperthyroidism (n/%) 2/6.9 0/0 - RaTHA, robot-assisted total hip arthroplasty; MTHA, manual total hip arthroplasty; BMI, body measurement index. Clinical Outcomes of RaTHA and MTHA Operative time was significantly longer in the RaTHA group (157.7 ± 6.2 min) than in the MTHA group (125 min, range: 65–290; p = 0.042) (Table 2 ). No significant differences were observed in red blood cell loss (0.60 ± 0.37 vs. 0.67 ± 0.48 × 10 9 , p = 0.524), hemoglobin loss (12.2 ± 2.1 vs. 19.5 ± 13.7 g/L, p = 0.705), or hematocrit reduction (5.7 ± 3.7 vs. 6.5 ± 4.1 L/L, p = 0.437). Transfusion rates were similar (15.2% vs. 20.7%, p = 0.569). A longer preoperative hospital stay is associated with the RaTHA group (5.3 ± 2.5 vs. 4.1 ± 1.5 days, p = 0.032), primarily for preoperative planning, but postoperative LOS did not differ (4.5 ± 1.2 vs. 4.6 ± 2.0 days, p = 0.727). Hospitalization costs (HC) were significantly higher in the RaTHA group (¥58,065.64 ± 10,814.04 vs. ¥47,255.26 ± 18,963.36, p = 0.008). Preoperative HHS showed no significant difference (MTHA: 53.9 ± 12.4; RaTHA: 57.7 ± 9.5; p = 0.179), and RaTHA demonstrated better HHS at 12 months postoperatively (85.2 ± 9.8 vs. 88.9 ± 6.5; p = 0.081). In summary, RaTHA was associated with longer operative times, higher costs, and prolonged preoperative LOS, and showed no better functional recovery than MTHA at 12 months. Table 2 Clinical outcomes of RaTHA and HcTHA. MTHA RaTHA P value Duration of operation (min) 125 (65,290) 157.7 ± 6.2 0.042/(Z=−2.038) Red blood cell loss(×10 9 ) 0.67 ± 0.48 0.60 ± 0.37 0.524/(t = 0.641) Hemoglobin loss (g/L) 19.5 ± 13.7 12.2 ± 2.1 0.705/(t = 0.381) Hematokrit (L/L) 6.5 ± 4.1 5.7 ± 3.7 0.437/(t = 0.782) Transfusion (n/ %) 6/20.7 5/15.2 0.569/(χ 2 =0.324) LOS (d) pre-op 4.1 ± 1.5 5.3 ± 2.5 0.032/(t=−2.195) pos-op 4.6 ± 2.0 4.5 ± 1.2 0.727/(t = 0.315) HC (¥) 47255.26 ± 18963.36 58065.64 ± 10814.04 0.008/(t=−2.746) HHS pre-op 53.9 ± 12.4 57.7 ± 9.5 0.179/(t=−1.361) 12m-pos-op 85.2 ± 9.8 88.9 ± 6.5 0.081/(t=−1,777) LOS, length of stay; HC, hospitalization costs, HHS, hip Harris score; pre-op, preoperatioin; pos-op, postoperation. Parameters of Hip Prosthesis No significant differences were observed in cup positioning: anteversion 16.2 ± 8.6°in MTHA vs. 14.5 ± 4.6°in RaTHA ( p = 0.311); inclination was 40.3 ± 8.1°vs. 42.7 ± 4.7° ( p = 0.152). Preoperatively ( p = 0.746) and postoperatively ( p = 0.392) LLD, femoral offset gap ( p = 0.536), and acetabular offset gap ( p = 0.429) did not differ significantly. These results indicate that although mean cup angles did not differ statistically, the RaTHA group exhibited less variability in cup positioning (Table 3 ). Table 3 Parameters of hip prosthesis. MTHA RaTHA P value Cup angles Anterversion (°) 16.2 ± 8.6 14.5 ± 4.6 0.311/(t = 1.022) Inclination (°) 40.3 ± 8.1 42.7 ± 4.7 0.153/(t=-1.447) LLD (mm) Pre-op 31(3,73) 23(10,55) 0.746/(Z = 0.323) Pos-op 4(0,20) 6(0,34) 0.392/(Z=-0.856) Femoral offset gap 7.1(0.5, 28.7) 8.6(1.2,28.1) 0.536/(Z=-0.618) Acetabular offset gap 6.4(0.1,23.1) 9.7(0.1,25.4) 0.429/(Z = 0.790) LLD, limb length discrepancy; HHS, hip Harris score. Postoperative Complications No infections, aseptic loosening, or deep vein thrombosis (DVT) occurred in either group. The RaTHA group had a 6.1% dislocation rate (2 cases), whereas no dislocations occurred in the MTHA group. Notably, both dislocated RaTHA patients had childhood histories of hip debridement or head-neck resection for septic arthritis, resulting in severe periarticular muscle atrophy or damage. Conversely, the MTHA group had a 20.7% incidence of iatrogenic acetabular defect (IAD) (6 cases), which did not occur in the RaTHA group. All six IADs were wall perforations, identified intraoperatively and confirmed by postoperative CT scan. Femoral nerve palsy rates were similar (MTHA: 6.9%, 2 cases; RaTHA: 6.1%, 2 cases) (Table 4 ). The numbness localized to the anterior aspect of the lower limbs was observed to ameliorate with hip flexion. Furthermore, this symptom had resolved completely by the six-month postoperative follow-up evaluation. In summary, the main differences were a higher acetabular defect rate in MTHA and dislocations exclusively in RaTHA, while other complications were comparable. Table 4 Postoperative complications. MTHA RaTHA Infection (n, %) 0, 0 0, 0 Dislocation (n, %) 0, 0 2, 6.1 AL (n, %) 0, 0 0, 0 LAD (n, %) 6, 20.7 0, 0 LLN (n, %) 2, 6.9 2, 6.1 DVT (n, %) 0, 0 0, 0 AL, aspetic loosening; LAD, latrogenic acetabular defect; LLN, lower limbs numbness; DVT, deep vein thrombosis. Discussions The utilization of RaTHA has been extensively studied in conventional hip osteoarthritis, with outcomes ranging from improved precision to equivocal clinical benefits [ 21 – 24 ]. However, its role in severe hip dislocation—a condition characterized by profound anatomical distortion and soft tissue compromise—remains poorly defined. This study is among the first prospective comparative evaluations specifically targeting this challenging cohort. Our early primary finding was that RaTHA demonstrated less variability in cup angles, a lower incidence of iatrogenic acetabular defects, but required longer operative times, higher costs and dislocation. Although there was no significant difference in the angles of cup, robotic assistance significantly reduced the variability in cup angles, as evidenced by smaller standard deviations for both inclination and anteversion angles. These results align with previous studies [ 25 – 27 ], and this improved consistency is attributable to the robotic system's ability to execute preoperative plans with high precision, preventing excessive reaming and minimizing the risk of acetabular wall perforation. This likely explains the absence of iatrogenic acetabular defects in the RaTHA group, contrasting with a 20.7% incidence (medial wall perforations) in the MTHA group. A complete bony coverage of the acetabulum helped encourage patients to start rehabilitation exercises earlier after surgery, which might contribute to the recovery of function. Although Zora et al. Reported comparable joint function between techniques for Crowe type Ⅲ-Ⅳ DDH, their results may be confounded by a substantially shorter follow-up [ 28 ]. Consistent with Chai et al.[ 29 ], robotic assistance did not confer significant benefits in controlling offset or leg length equality in severe dislocations, and it incurred longer operative times and higher costs—a trade-off requiring careful consideration. The additional time for preoperation planning and intraoperative registration inherent to current robotic technology and varies with anatomical complexity and surgeons’ experience [ 29 , 30 ]. Zhou et al. reported no significant increase in operative time or blood loss with RaTHA, potentially due to surgeon expertise, streamlined workflow, and a cohort comprising mainly mild-to-moderate DDH cases [ 31 ]. Although prolonged surgery has been associated with increased blood loss in some studies [ 32 ], our protocol—incorporating pre-osteotomy reference array placement, tranexamic acid administration, and controlled hypotension—effectively mitigated this risk, resulting in no intergroup difference in hemorrhage [ 33 , 34 ]. This suggests that technical and pharmacological strategies can offset one commonly cited drawback of robotic assistance. A key finding was the absence of significant differences in mean cup alignment between groups, despite improved consistency in the robotic cohort. Ando et al. similarly reported lower dislocation rates with RaTHA and no difference in anteversion among Crowe type I/II cases [ 35 ]. Chai et al. found no difference in inclination accuracy but a higher probability of safe zone placement in Crowe III/IV patients undergoing RaTHA [ 29 ]. Zhou et al. also observed no significant difference in cup angles but more cases within safe zones with RaTHA across Crowe types I-IV [ 31 ]. This reflects the ability of experienced surgeons to achieve excellent manual placement on average, underscoring that technology cannot fully replace surgical expertise. Nevertheless, the reduced variability in the robotic group reinforces its role in enhancing reproducibility—particularly valuable in complex anatomy. Notably, despite reduced variability in cup positioning in the robotic group, two early dislocations occurred, both attributable to severe soft tissue deficiency from childhood septic arthritis sequelae. This highlights a fundamental limitation of current robotic systems (MAKO 3.0): planning is based solely on static bony anatomy, with no capacity to address dynamic soft tissue stability, which is crucial for postoperative hip function and prosthesis stability [ 36 ]. This insight shifts the focus from purely technical precision to a more holistic approach, emphasizing that osseous accuracy alone may be insufficient in patients with significant soft tissue compromise. Complication rates were low and comparable between groups, likely due to standardized perioperative protocols including antibiotic prophylaxis, multimodal thromboprophylaxis, and structured rehabilitation. Nerve traction symptoms occurred at similar rates, reflecting the inherent challenge of lengthening severely contracted limbs regardless of surgical technique [ 2 , 37 ]. Several limitations should be acknowledgment. The sample size, though substantial for this rare condition, remains modest. The non-blinded design and additional cost of robotics may have introduced selection and performance bias. Future research requires randomized controlled trials (RCTs) to eliminate such selection bias. Short-term follow-up precludes assessment of long-term implant survivorship, functional sustainability, or cost-effectiveness. Conclusion This study suggested that RaTHA could be beneficial only for patients with severe hip dislocation accompanied by bony structural deformities. It could reduce variability in acetabular cup positioning and lower the risk of iatrogenic acetabular wall perforation, which might facilitate the early recovery of function. However, RaTHA did not demonstrate superior advantages over manual THA in terms of mean cup positioning, LLD control, or offset restoration, and was associated with increased operative time and costs. A critical finding was the occurrence of dislocations in the robotic group despite improved cup consistency, underscoring the technology's current inability to address soft tissue instability and the irreplaceable role of surgical judgment in managing soft tissues. The clinical value of robotic assistance may be further enhanced by future developments that integrate dynamic soft tissue assessment into preoperative planning, allowing for the definition of individualized safe angles for prosthesis implantation. Declarations Data availability statement: All the data in the study are available from the corresponding author on reasonable request. Funding statement: This work was supported by fundings for Clinical Trials from the Affiliated Drum Tower Hospital, Medical School of Nanjing University （2022-LCYJ-MS-21，2024-LCYJ-PY-82）and Nanjing Municipal Health Science and Technology Development Project （YKK24103）and Key Project Supported by Medical Science and Technology Development Foundation, Nanjing Department of Health （YKK24103）. Ethics approval and consent to participate: This study adheres to the Declaration of Helsinki and was approved by the Ethics Committee of Nanjing Drum Tower Hospital (Approval No.:2022-448-01). Written informed consent was obtained from all patients after detailed explanation of the surgical procedure and research objectives. Conflict of interest disclosure: The authors declare no conflicts of interest. Authorship Contribution Statement Yu Zhang: Conceptualization, Methodology, Writing - Original Draft. Wentian Gao: Formal analysis, Investigation, Data Curation. Qiangqiang Li: Software, Validation, Visualization. Aikeremu Aierken: Resources, Investigation. Yao Yao: Investigation, Data Curation. Peng Sun: Data Curation, Software. Yuejian Ding: Data Curation, Software. Qing Jiang: Supervision, Review, Project administration. Dongyang Chen: Supervision, Funding acquisition, Project administration. Consent for publication: Not applicable. References Esmaeili S, Ghaseminejad-Raeini A, Ghane G, et al (2024) Total Hip Arthroplasty in Patients Who Have Crowe Type IV Developmental Dysplasia of the Hip: A Systematic Review. The Journal of Arthroplasty 39:2645-2660.e19. https://doi.org/10.1016/j.arth.2024.05.031 Poursalehian M, Hassanzadeh A, Shafiei SH, Mortazavi SMJ (2025) Mid- to Long-Term Outcomes and Complications of Total Hip Arthroplasty in Patients Who Have Crowe IV Developmental Dysplasia of the Hip: A Systematic Review and Meta-Analysis. 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JBJS Reviews 13:. https://doi.org/10.2106/JBJS.RVW.25.00091 Zhang Y, Wang Z, Yuan J, et al (2025) Impact of Robotic-Assisted Technology on Joint Awareness Following Total Joint Arthroplasty: A Systematic Review and Meta-Analysis. The Journal of Arthroplasty S0883540325010290. https://doi.org/10.1016/j.arth.2025.08.024 Zhang Y, Li S, Liu X, et al (2025) Robot-Assisted Total Hip Arthroplasty Versus Conventional Surgery in Terms of Surgical Accuracy, Function, Trauma, and Complications: A Prospective, Multicenter, Parallel-Group, Open-Label Randomized Controlled Trial. The Journal of Arthroplasty S0883540325008927. https://doi.org/10.1016/j.arth.2025.07.029 Hahn AK, Bauer JA, Megalla M, Grosso MJ (2025) Dislocation Rates Between Manual and Robotic-Assisted Total Hip Arthroplasty Using the Posterolateral Approach. J Am Acad Orthop Surg. https://doi.org/10.5435/JAAOS-D-24-01502 Howell C, Witvoet S, Scholl L, et al (2025) Postoperative Complications and Readmission Rates in Robotic-Assisted and Manual Total Hip Arthroplasty: A Large, Multi-Hospital Study. Medical Care 63:465–471. https://doi.org/10.1097/MLR.0000000000002082 Zhang X, Shen X, Zhang R, et al (2024) Radiographic evaluation of robot-assisted versus manual total hip arthroplasty: a multicenter randomized controlled trial. J Orthop Traumatol 25:33. https://doi.org/10.1186/s10195-024-00773-3 Lim PL, Gonzalez MR, Wang KY, et al (2025) Does Robotic Assistance Increase the Likelihood of Achieving the Minimal Clinically Important Improvement Following Total Hip Arthroplasty? Findings From a Propensity Score Matched Analysis of 1,364 Procedures. The Journal of Arthroplasty S0883540325005108. https://doi.org/10.1016/j.arth.2025.05.015 Zepeda KE, Burgio C, Karasavvidis T, et al (2025) Impact of Robotic Assistance on Total Hip Arthroplasty: Granular Insights Into Surgical Time. The Journal of Arthroplasty 40:S172–S178. https://doi.org/10.1016/j.arth.2025.03.068 Sacher SE, A. O’Donnell J, Wright TM, et al (2025) Robotic-Assisted Surgery Does Not Decrease Prosthetic Impingement in Total Hip Arthroplasty: A Retrieval Analysis. The Journal of Arthroplasty 40:S333–S337. https://doi.org/10.1016/j.arth.2025.02.077 Shi H, Yu R, Pu L, et al (2025) Application and exploration of total hip arthroplasty for developmental dysplasia of the hip assisted by full-process robotics. BMC Musculoskelet Disord 26:225. https://doi.org/10.1186/s12891-025-08460-y Guo D, Li X, Ma S, et al (2022) Total Hip Arthroplasty with Robotic Arm Assistance for Precise Cup Positioning: A Case‐Control Study. Orthopaedic Surgery 14:1498–1505. https://doi.org/10.1111/os.13334 Xu S, Bernardo L, Yew K, Pang H (2020) Robotic-Arm Assisted Direct Anterior Total Hip Arthroplasty; Improving Implant Accuracy. Surg Technol Int PMID: 33368137. https://doi.org/10.52198/21.STI.38.OS1368 Bensa A, Pagliazzi G, Miele A, et al (2025) Robotic-Assisted Total Hip Arthroplasty Provides Greater Implant Placement Accuracy and Lower Complication Rates, but Not Superior Clinical Results Compared to the Conventional Manual Approach: A Systematic Review and Meta-Analysis. The Journal of Arthroplasty 40:1921–1931. https://doi.org/10.1016/j.arth.2024.12.014 Zora H, Bayrak G, Bilgen ÖF (2025) Robotically Assisted vs. Manual Total Hip Arthroplasty in Developmental Hip Dysplasia: A Comparative Analysis of Radiological and Functional Outcomes. JCM 14:509. https://doi.org/10.3390/jcm14020509 Chai W, Xu C, Guo R-W, et al (2022) Does robotic-assisted computer navigation improve acetabular cup positioning in total hip arthroplasty for Crowe III/IV hip dysplasia? A propensity score case-match analysis. International Orthopaedics (SICOT) 46:769–777. https://doi.org/10.1007/s00264-021-05232-w Sato K, Sato A, Okuda N, et al (2022) A propensity score-matched comparison between Mako robotic arm-assisted system and conventional technique in total hip arthroplasty for patients with osteoarthritis secondary to developmental dysplasia of the hip. Arch Orthop Trauma Surg 143:2755–2761. https://doi.org/10.1007/s00402-022-04524-z Zhou Y, Shao H, Huang Y, et al (2021) Does robotic assisted technology improve the accuracy of acetabular component positioning in patients with DDH? J Orthop Surg (Hong Kong) 29:23094990211025325. https://doi.org/10.1177/23094990211025325 Ross D, Erkocak O, Rasouli MR, Parvizi J (2019) Operative Time Directly Correlates with Blood Loss and Need for Blood Transfusion in Total Joint Arthroplasty. Arch Bone Jt Surg 7:229–234 Boucher M, Tremblay J, Pelet T, et al (2025) Topical Versus Systemic Tranexamic Acid to Reduce Blood Loss After Total Knee and Total Hip Arthroplasty: A Systematic Review and Meta-Analysis. Journal of Bone and Joint Surgery. https://doi.org/10.2106/JBJS.24.01511 Zhang Q, Yin S, Huang K, et al (2021) [Effectiveness and safety of tranexamic acid combined with intraoperative controlled hypotension on reducing perioperative blood loss in primary total hip arthroplasty]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 35:1133–1140. https://doi.org/10.7507/1002-1892.202103230 Ando W, Takao M, Hamada H, et al (2021) Comparison of the accuracy of the cup position and orientation in total hip arthroplasty for osteoarthritis secondary to developmental dysplasia of the hip between the Mako robotic arm-assisted system and computed tomography-based navigation. International Orthopaedics (SICOT) 45:1719–1725. https://doi.org/10.1007/s00264-021-05015-3 Byeon N, Shin J, Kim S, et al (2025) Comparative Study of the Rehabilitation Exercise 5R System and Aerobic Exercise on Postpartum Recovery: Impacts on Muscle Function and Metabolic Health. Med Sci Monit 31:. https://doi.org/10.12659/MSM.947877 Taheriazam A, Baghbani S, Malakooti M, et al (2024) Neuromonitoring in pre-post and intraoperative total hip replacement surgery in type 4 high-riding developmental dysplasia of the hip. European Review for Medical and Pharmacological Sciences 28:98–106. https://doi.org/10.26355/eurrev_202401_34895 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8512197","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":589045156,"identity":"65ac55b6-8d82-43f6-9067-8f5dc5ed5e77","order_by":0,"name":"Yu Zhang","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Zhang","suffix":""},{"id":589045157,"identity":"e286d474-5c12-4359-9259-5ef825d73891","order_by":1,"name":"Wentian Gao","email":"","orcid":"","institution":"Drum Tower Hospital Affiliated of Nanjing University Medical School","correspondingAuthor":false,"prefix":"","firstName":"Wentian","middleName":"","lastName":"Gao","suffix":""},{"id":589045158,"identity":"0ddb8e32-caf7-4075-baf5-5ab7c8d21f5d","order_by":2,"name":"Qiangqiang Li","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Qiangqiang","middleName":"","lastName":"Li","suffix":""},{"id":589045160,"identity":"80d5bc64-938e-4b52-a918-937fba986940","order_by":3,"name":"Aikeremu Aierken","email":"","orcid":"","institution":"Drum Tower Hospital Affiliated of Nanjing University Medical School","correspondingAuthor":false,"prefix":"","firstName":"Aikeremu","middleName":"","lastName":"Aierken","suffix":""},{"id":589045163,"identity":"fb90e90d-a16a-4cb9-933d-64916c346125","order_by":4,"name":"Yao Yao","email":"","orcid":"","institution":"Drum Tower Hospital Affiliated of Nanjing University Medical School","correspondingAuthor":false,"prefix":"","firstName":"Yao","middleName":"","lastName":"Yao","suffix":""},{"id":589045164,"identity":"2f64b80c-a555-417c-96f4-31f0c7ffa315","order_by":5,"name":"Peng Sun","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Peng","middleName":"","lastName":"Sun","suffix":""},{"id":589045165,"identity":"cfc69032-32c4-45e3-994f-7c781f3955f6","order_by":6,"name":"Yuejian Ding","email":"","orcid":"","institution":"Drum Tower Hospital Affiliated of Nanjing University Medical School","correspondingAuthor":false,"prefix":"","firstName":"Yuejian","middleName":"","lastName":"Ding","suffix":""},{"id":589045167,"identity":"df5a2deb-ef97-4262-b481-baadc9fd1b6a","order_by":7,"name":"Qing Jiang","email":"","orcid":"","institution":"Drum Tower Hospital Affiliated of Nanjing University Medical School","correspondingAuthor":false,"prefix":"","firstName":"Qing","middleName":"","lastName":"Jiang","suffix":""},{"id":589045168,"identity":"789e5bc6-62cb-41e3-a142-fada5d41a4e7","order_by":8,"name":"Dongyang Chen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwklEQVRIiWNgGAWjYBACfvbmA4f/VNjw8BOtRbLnWOIBnjNpMpINxGoxuJGjfIC35bCNwQGirTlzhuGAZAMzj/Hx5A0MPyq2EdbB2N574IDhDjYeszPPChh7ztwmrIWZ51zCgcQzPDxmN3IMmBnbiNDCJpFjcOBgmwSP8QxitfAAtRxsbDPgMZAgVosEz7GEwwxnEngkgH45SJRf7I83H/7MUPHfnr89eeODHxVEaEECCSREDVwLqTpGwSgYBaNghAAAYwBBufxRTC0AAAAASUVORK5CYII=","orcid":"","institution":"Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University","correspondingAuthor":true,"prefix":"","firstName":"Dongyang","middleName":"","lastName":"Chen","suffix":""}],"badges":[],"createdAt":"2026-01-04 10:08:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8512197/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8512197/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102380101,"identity":"f90eafa3-fb41-42fa-a9cc-6533323d5ca2","added_by":"auto","created_at":"2026-02-11 06:36:24","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":378626,"visible":true,"origin":"","legend":"\u003cp\u003eCONSORT flow diagram illustrating patient screening, grouping, propensity score matching, and follow-up for the comparative study of robot-assisted versus manual THA in severe hip dislocations.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8512197/v1/0336f4c87b19d47ccf52bc84.jpeg"},{"id":106586777,"identity":"d4be2e48-3dc9-45bf-b030-e79376e60c2f","added_by":"auto","created_at":"2026-04-10 07:43:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1165290,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8512197/v1/ba1cc599-7bea-4603-a758-f1fcf20ddd87.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"How Much Benefit Can Robot-Assisted Total Hip Arthroplasty Provide for Patients with Severe Hip Dislocation? -a Propensity Score-Matched Analysis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eVarious reasons (such as congenital hip dysplasia and postoperative hip joint infection in childhood) leading to severe hip dislocation pose significant challenges for surgical treatment [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. These include abnormal acetabular bony structures, such as shallow and small acetabula and shortened acetabular roofs, which compromise the acetabulum's ability to adequately cover the femoral head [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Additionally, the formation of pseudoacetabula resulting from chronic dislocation further complicates the surgical procedure by obscuring normal anatomical landmarks[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. A narrow proximal medullary canal adds to the difficulty [\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Moreover, patients often present with significant leg length discrepancy and associated muscle atrophy or deficiency [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], further increasing surgical complexity. This is particularly critical in cases with severe femoral head dislocation and muscle atrophy/loss subsequent to childhood hip osteotomy or suppurative hip arthritis.These anomalies collectively elevate surgical difficulty and contribute to a higher incidence of postoperative complications, including intraoperative acetabular or proximal femoral fractures, leg length discrepancy, hip dislocations, prolonged operative times with increased blood loss, and elevated infection risks [\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRecent advancements in robot-assisted surgery have introduced new possibilities in the field of THA[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Robotic systems enable surgeons to perform individualized preoperative planning for complex hip arthroplasty, including prosthesis positioning and alignment, selection of prosthesis type, and control of leg length discrepancy and offset. Intraoperatively, robotic arms assist in precisely locating the true acetabulum and accurately positioning the acetabular cup, theoretically reducing the risk of prosthesis malalignment, wear and postoperative dislocation [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. While robot-assisted THA has been widely applied in common hip pathologies, its potential benefits in severe hip dislocations remain relatively unexplored. The primary aim of this study was to compare the early functional recovery, assessed by the Harris Hip Score (HHS) at 12 months postoperatively, between RaTHA and MTHA in patients with severe hip dislocations (Crowe type III/IV). Secondary aims were to compare perioperative indicators (operative time, blood loss, length of stay, costs), radiographic outcomes (cup positioning, limb length discrepancy, offset), and complication rates. Through a propensity score-matched study, we seek to guide clinical practice by clarifying how robot-assisted surgery can benefit patients with severe hip dislocations, thereby enhancing the understanding and application of this emerging technology.\u003c/p\u003e"},{"header":"Methods and Materials","content":"\u003cp\u003e\u003cstrong\u003eStudy Design and Patients Recruitment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis propensity score-matched study was approved by the institutional review board (2022-448-01). Patients aged 18-75 years diagnosed with severe hip joint dislocation (Crowe type\u0026nbsp;Ⅲ\u0026nbsp;or\u0026nbsp;Ⅳ) were enrolled. All patients provided written informed consent. Exclusion criteria included neuromuscular dysfunction, hip infection, revision hip arthroplasty, and severe medical or surgical comorbidities. Patient allocation to the robot-assisted THA (RaTHA) group or manual (MTHA) group was as follows:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1. RaTHA Group (n=33):\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; - Consecutive patients who voluntarily chose robotic-assisted surgery.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; - All procedures were performed by fellowship-trained arthroplasty surgeons using the MAKO robotic platform (MAKO 3.0, Stryker, USA).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2. MTHA Group (n=29):\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; - Patients undergoing manual THA during the same period.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; - comprised exclusively of patients who declined robotic assistance due to personal preference or financial constraints, despite its availability.\u003c/p\u003e\n\u003cp\u003eTo minimize selection bias, propensity score matching was performed using nearest-neighbor matching (1:1) with a caliper width of 0.2 standard deviations, based on:\u003c/p\u003e\n\u003cp\u003e- Demographic factors (age \u0026plusmn;5 years, sex, BMI \u0026plusmn;3 kg/m\u0026sup2;)\u003c/p\u003e\n\u003cp\u003e- Disease severity (Crowe classification III/IV, radiographic dislocation height)\u003c/p\u003e\n\u003cp\u003e- Surgical year (within a 2-year window)\u003c/p\u003e\n\u003cp\u003eMatching achieved excellent balance (all standardized mean differences \u0026lt;0.1). Both groups received identical implant systems and postoperative protocols. The CONSORT flow diagram. (Figure 1)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSample Size Consideration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGiven the rarity of severe hip dislocations (Crowe III/IV) requiring THA and the prospective nature of this study, a formal sample size calculation was not performed a priori. Instead, a feasibility approach was adopted, aiming to include all eligible patients presenting during the study period. Post-hoc power analysis indicated that the achieved sample size (n=62) provided 80% power to detect a moderate effect size (Cohen\u0026apos;s d = 0.65) in the primary outcome (HHS at 12 months) with a two-sided \u0026alpha; of 0.05.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSurgical Procedures\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll THA procedures were performed under intravenous anesthesia combined with lumbar plexus nerve block, with patients in the supine position via an anterior approach.\u003c/p\u003e\n\u003cp\u003eA 10 cm longitudinal incision was made 1.5 cm lateral to the line connecting the anterior superior iliac spine and the fibular head. After incising the deep fascia, the sartorius, rectus femoris, and tensor fascia latae muscles were retracted medially and laterally to expose the intermuscular interval. The superior branch of the lateral circumflex femoral vessels were ligated, and the anterior capsule was excised to expose the femoral head and neck. To improve surgical exposure and facilitate reduction, the tensor fasciae latae insertion at the iliac tuberosity was released. An initial femoral neck was performed, followed by removal of soft tissues such as the labrum, ligamentum teres remnant, and acetabulum fat pad. The joint capsule posterior to the greater trochanter was also released.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eManual THA (MTHA) Group:\u003c/strong\u003e Acetabular preparation was performed based on surgical experience\u0026nbsp;of fellowship-trained arthroplasty surgeons. Sequential acetabular reamers of increasing sizes were used to ream the acetabulum concentrically, considering the femoral head size. Reaming was performed at 40\u0026deg; abduction and 10\u0026deg;-15\u0026deg; anteversion until the medial acetabular cortex was reached. The corresponding acetabular cup was then implanted at 40\u0026deg; abduction and 10\u0026deg;-15\u0026deg; anteversion, with supplemental screw fixation posterolaterally. The liner was subsequently placed. The lower limb was then extended, externally rotated, and adducted, and the proximal femur was elevated to expose the femoral osteotomy surface. Sequential femoral reamers were used to prepare the medullary canal until stability was achieved. The corresponding femoral stem was implanted, followed by selection and placement of an appropriate sized femoral head, and reduction was performed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRobot-assisted THA (RaTHA) Group :\u0026nbsp;\u003c/strong\u003ePreoperatively, three-dimensional hip models were from pelvic and proximal femoral CT data using robotic software. Based on acetabular anatomy of the affected and healthy sides, prosthesis size and positioning were planned at the true acetabulum, ensuring acetabular wall integrity and optimal prosthesis size. Femoral stem type was selected according to proximal femoral morphology and medullary canal dimensions. Three pins were inserted into the anterior superior iliac spine on the operative side to secure the pelvic reference array, and a registration screw was placed in a well-exposed bone anterior and superior to the acetabulum. After instrument calibration, acetabulum registration was performed by selecting well-exposed bony landmarks to minimize error. With robotic arm assistance, the acetabular bone bed was prepared according to the planned size and prosthesis model, and the corresponding acetabular prosthesis was implanted. Femoral preparation was identical to the MTHA group.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePostoperative Treatments and Rehabilitation Protocols\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDuring the first month after surgery, the patient should primarily rest at home and avoid excessive activity to facilitate the healing of the extensively released soft tissues. Local anti-inflammatory, anti-edema, and analgesic treatments were applied to the incision. Concurrently, ankle pump exercise and range of motion training for non-hip joints were encouraged to reduce the risk of thrombosis and joint contracture. After one month, the patient should appropriately increase outdoor activities to exercise muscle strength in the affected limb and train coordination of walking gait and proprioception. In the event that the patient develops symptoms of femoral nerve palsy in the lower limbs postoperatively, neurotrophic therapy will be initiated, and a hip brace will be applied to maintain the hip in a flexed position, thereby alleviating symptoms associated with nerve traction. In cases where the patient undergoes proximal femoral osteotomy or intra-operative acetabular wall perforation occurs, a period of 3-month strict bed rest is mandated postoperatively. This protocol is implemented to facilitate bone union and ensure the stability of the prosthetic implant.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical and Radiographic Evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBaseline data including age, sex, hip dislocation severity (Crowe type\u0026nbsp;Ⅲ\u0026nbsp;or\u0026nbsp;Ⅳ), BMI, limb length discrepancy (LLD), and preoperative HHS were collected and compared. Operative duration, intraoperative blood loss, transfusion rate, length of stay (LOS), and surgery-related complications were recorded and compared. Blood loss was calculated based on the difference in hemoglobin and hematocrit levels between preoperative and postoperative day 1. Radiographic evaluation (X-ray and CT) assessed acetabular cup abduction, anteversion angles, offset, LLD, and wall perforation[20]. Follow-up was conducted until 12 months after the surgery, during which the short-term joint function and the occurrence of surgery-related complications were observed and evaluated, including HHS, intraoperative acetabular wall perforation, postoperative prosthesis dislocation, wound infection, prosthesis loosening, and deep vein thrombosis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData were analyzed using SPSS 28.0 (IBM, USA). continuous variables (age, BMI, HHS, blood loss, LOS,\u0026nbsp;HC,\u0026nbsp;cup angles) were tested for normality. Normally distributed data were expressed as mean\u0026nbsp;\u0026plusmn;\u0026nbsp;standard deviation and compared using independent two-sample t-test. Skewed data (LLD, femoral and acetabular offset gaps) were expressed as medians (minimum, maximum) and analyzed using the Mann-Whitney U test. Complication rates were expressed as proportions and compared using the Chi-square test. A \u003cem\u003eP\u003c/em\u003e-value \u0026lt; 0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eBaseline Clinical Characteristics\u003c/h2\u003e \u003cp\u003eBetween January 2022 and June 2025, a total of 70 patients (74 hips) were enrolled in the clinical study. Of these, 34 patients (36 hips) underwent robotic-assisted surgery, while the remaining 36 patients (38 hips) received manual surgery. Following propensity score matching, four patients from the manual surgery group were excluded. Ultimately, after a postoperative follow-up period of 12 months, follow-up data were available for 33 patients (35 hips) in the robotic group and 29 patients (31 hips) in the manual group (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eBaseline characteristics were well-balanced between the MTHA and RaTHA groups (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Mean age was similar (MTHA: 48.9\u0026thinsp;\u0026plusmn;\u0026thinsp;10.2 years; RaTHA: 49.1\u0026thinsp;\u0026plusmn;\u0026thinsp;14.1 years; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.967). Sex distribution did not differ significantly, with males comprising 20.7% (6/29) in MTHA and 27.3% (9/33) in RaTHA (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.546). Operative side was balanced (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.988). Crowe type distribution was comparable (type III: 35.5% vs. 42.9%; type IV: 64.5% vs. 57.1%; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.541). BMI values were similar (23.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0 vs. 23.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.652). Comorbidities, including prior surgical history (18.2% vs. 13.8%; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.360) and hypertension (10.3% vs. 18.2%; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.382), showed no significant differences, although hyperthyroidism was only reported in the MTHA group (6.9% vs. 0%). Overall, the groups were well-matched, minimizing confounding bias.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline clinical characteristics.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMTHA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRaTHA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eage\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48.9\u0026thinsp;\u0026plusmn;\u0026thinsp;10.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e49.1\u0026thinsp;\u0026plusmn;\u0026thinsp;14.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.967/(t=\u0026minus;0.041)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emale(n/%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6/20.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9/27.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.546/(χ\u003csup\u003e2\u003c/sup\u003e=0.365)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003efemale(n/%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23/79.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24/72.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eOperative side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eleft(n,%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16/51.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e18/51.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.988/(χ\u003csup\u003e2\u003c/sup\u003e=0.000)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eright(n,%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15/48.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17/48.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCrowe type\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11/35.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15/42.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.541/(χ\u003csup\u003e2\u003c/sup\u003e=0.374)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eⅣ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20/64.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20/57.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eBMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.652/(t=\u0026thinsp;0.453)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003ecomorbitities\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ehistory of surgical intervention\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6/18.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4/13.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.360/(χ\u003csup\u003e2\u003c/sup\u003e=0.838)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ehypertension(n/%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3/10.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6/18.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.382/(χ\u003csup\u003e2\u003c/sup\u003e=0.764)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHyperthyroidism\u003c/p\u003e \u003cp\u003e(n/%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2/6.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0/0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eRaTHA, robot-assisted total hip arthroplasty; MTHA, manual total hip arthroplasty; BMI, body measurement index.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eClinical Outcomes of RaTHA and MTHA\u003c/h2\u003e \u003cp\u003eOperative time was significantly longer in the RaTHA group (157.7\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2 min) than in the MTHA group (125 min, range: 65\u0026ndash;290; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.042) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). No significant differences were observed in red blood cell loss (0.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37 vs. 0.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48 \u0026times; 10\u003csup\u003e9\u003c/sup\u003e, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.524), hemoglobin loss (12.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 vs. 19.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.7 g/L, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.705), or hematocrit reduction (5.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7 vs. 6.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1 L/L, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.437). Transfusion rates were similar (15.2% vs. 20.7%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.569).\u003c/p\u003e \u003cp\u003eA longer preoperative hospital stay is associated with the RaTHA group (5.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5 vs. 4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5 days, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032), primarily for preoperative planning, but postoperative LOS did not differ (4.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2 vs. 4.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0 days, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.727). Hospitalization costs (HC) were significantly higher in the RaTHA group (\u0026yen;58,065.64\u0026thinsp;\u0026plusmn;\u0026thinsp;10,814.04 vs. \u0026yen;47,255.26\u0026thinsp;\u0026plusmn;\u0026thinsp;18,963.36, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008).\u003c/p\u003e \u003cp\u003ePreoperative HHS showed no significant difference (MTHA: 53.9\u0026thinsp;\u0026plusmn;\u0026thinsp;12.4; RaTHA: 57.7\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.179), and RaTHA demonstrated better HHS at 12 months postoperatively (85.2\u0026thinsp;\u0026plusmn;\u0026thinsp;9.8 vs. 88.9\u0026thinsp;\u0026plusmn;\u0026thinsp;6.5; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.081).\u003c/p\u003e \u003cp\u003eIn summary, RaTHA was associated with longer operative times, higher costs, and prolonged preoperative LOS, and showed no better functional recovery than MTHA at 12 months.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical outcomes of RaTHA and HcTHA.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMTHA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRaTHA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eDuration of operation (min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e125 (65,290)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e157.7\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.042/(Z=\u0026minus;2.038)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eRed blood cell loss(\u0026times;10\u003csup\u003e9\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.524/(t\u0026thinsp;=\u0026thinsp;0.641)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eHemoglobin loss (g/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.705/(t\u0026thinsp;=\u0026thinsp;0.381)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eHematokrit (L/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.437/(t\u0026thinsp;=\u0026thinsp;0.782)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eTransfusion (n/ %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6/20.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5/15.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.569/(χ\u003csup\u003e2\u003c/sup\u003e=0.324)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eLOS (d)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003epre-op\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.032/(t=\u0026minus;2.195)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003epos-op\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.727/(t\u0026thinsp;=\u0026thinsp;0.315)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eHC (\u0026yen;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e47255.26\u0026thinsp;\u0026plusmn;\u0026thinsp;18963.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e58065.64\u0026thinsp;\u0026plusmn;\u0026thinsp;10814.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.008/(t=\u0026minus;2.746)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eHHS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003epre-op\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.9\u0026thinsp;\u0026plusmn;\u0026thinsp;12.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e57.7\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.179/(t=\u0026minus;1.361)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12m-pos-op\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e85.2\u0026thinsp;\u0026plusmn;\u0026thinsp;9.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e88.9\u0026thinsp;\u0026plusmn;\u0026thinsp;6.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.081/(t=\u0026minus;1,777)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eLOS, length of stay; HC, hospitalization costs, HHS, hip Harris score; pre-op, preoperatioin; pos-op, postoperation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eParameters of Hip Prosthesis\u003c/h2\u003e \u003cp\u003eNo significant differences were observed in cup positioning: anteversion 16.2\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u0026deg;in MTHA vs. 14.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.6\u0026deg;in RaTHA (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.311); inclination was 40.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.1\u0026deg;vs. 42.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.7\u0026deg; (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.152). Preoperatively (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.746) and postoperatively (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.392) LLD, femoral offset gap (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.536), and acetabular offset gap (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.429) did not differ significantly. These results indicate that although mean cup angles did not differ statistically, the RaTHA group exhibited less variability in cup positioning (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eParameters of hip prosthesis.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMTHA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRaTHA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCup angles\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAnterversion (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.2\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.311/(t\u0026thinsp;=\u0026thinsp;1.022)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInclination (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e42.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.153/(t=-1.447)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eLLD (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePre-op\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31(3,73)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23(10,55)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.746/(Z\u0026thinsp;=\u0026thinsp;0.323)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePos-op\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4(0,20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6(0,34)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.392/(Z=-0.856)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eFemoral offset gap\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.1(0.5, 28.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.6(1.2,28.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.536/(Z=-0.618)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eAcetabular offset gap\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.4(0.1,23.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.7(0.1,25.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.429/(Z\u0026thinsp;=\u0026thinsp;0.790)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eLLD, limb length discrepancy; HHS, hip Harris score.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003ePostoperative Complications\u003c/h2\u003e \u003cp\u003eNo infections, aseptic loosening, or deep vein thrombosis (DVT) occurred in either group. The RaTHA group had a 6.1% dislocation rate (2 cases), whereas no dislocations occurred in the MTHA group. Notably, both dislocated RaTHA patients had childhood histories of hip debridement or head-neck resection for septic arthritis, resulting in severe periarticular muscle atrophy or damage. Conversely, the MTHA group had a 20.7% incidence of iatrogenic acetabular defect (IAD) (6 cases), which did not occur in the RaTHA group. All six IADs were wall perforations, identified intraoperatively and confirmed by postoperative CT scan. Femoral nerve palsy rates were similar (MTHA: 6.9%, 2 cases; RaTHA: 6.1%, 2 cases) (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The numbness localized to the anterior aspect of the lower limbs was observed to ameliorate with hip flexion. Furthermore, this symptom had resolved completely by the six-month postoperative follow-up evaluation.\u003c/p\u003e \u003cp\u003eIn summary, the main differences were a higher acetabular defect rate in MTHA and dislocations exclusively in RaTHA, while other complications were comparable.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePostoperative complications.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMTHA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRaTHA\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInfection (n, %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0, 0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0, 0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDislocation (n, %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0, 0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2, 6.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAL (n, %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0, 0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0, 0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLAD (n, %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6, 20.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0, 0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLLN (n, %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2, 6.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2, 6.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDVT (n, %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0, 0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0, 0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAL, aspetic loosening; LAD, latrogenic acetabular defect; LLN, lower limbs numbness; DVT, deep vein thrombosis.\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussions","content":"\u003cp\u003eThe utilization of RaTHA has been extensively studied in conventional hip osteoarthritis, with outcomes ranging from improved precision to equivocal clinical benefits [\u003cspan additionalcitationids=\"CR22 CR23\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. However, its role in severe hip dislocation\u0026mdash;a condition characterized by profound anatomical distortion and soft tissue compromise\u0026mdash;remains poorly defined. This study is among the first prospective comparative evaluations specifically targeting this challenging cohort. Our early primary finding was that RaTHA demonstrated less variability in cup angles, a lower incidence of iatrogenic acetabular defects, but required longer operative times, higher costs and dislocation.\u003c/p\u003e \u003cp\u003eAlthough there was no significant difference in the angles of cup, robotic assistance significantly reduced the variability in cup angles, as evidenced by smaller standard deviations for both inclination and anteversion angles. These results align with previous studies [\u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], and this improved consistency is attributable to the robotic system's ability to execute preoperative plans with high precision, preventing excessive reaming and minimizing the risk of acetabular wall perforation. This likely explains the absence of iatrogenic acetabular defects in the RaTHA group, contrasting with a 20.7% incidence (medial wall perforations) in the MTHA group. A complete bony coverage of the acetabulum helped encourage patients to start rehabilitation exercises earlier after surgery, which might contribute to the recovery of function. Although Zora et al. Reported comparable joint function between techniques for Crowe type Ⅲ-Ⅳ DDH, their results may be confounded by a substantially shorter follow-up [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Consistent with Chai et al.[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], robotic assistance did not confer significant benefits in controlling offset or leg length equality in severe dislocations, and it incurred longer operative times and higher costs\u0026mdash;a trade-off requiring careful consideration.\u003c/p\u003e \u003cp\u003eThe additional time for preoperation planning and intraoperative registration inherent to current robotic technology and varies with anatomical complexity and surgeons\u0026rsquo; experience [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Zhou et al. reported no significant increase in operative time or blood loss with RaTHA, potentially due to surgeon expertise, streamlined workflow, and a cohort comprising mainly mild-to-moderate DDH cases [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Although prolonged surgery has been associated with increased blood loss in some studies [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], our protocol\u0026mdash;incorporating pre-osteotomy reference array placement, tranexamic acid administration, and controlled hypotension\u0026mdash;effectively mitigated this risk, resulting in no intergroup difference in hemorrhage [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. This suggests that technical and pharmacological strategies can offset one commonly cited drawback of robotic assistance.\u003c/p\u003e \u003cp\u003eA key finding was the absence of significant differences in mean cup alignment between groups, despite improved consistency in the robotic cohort. Ando et al. similarly reported lower dislocation rates with RaTHA and no difference in anteversion among Crowe type I/II cases [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Chai et al. found no difference in inclination accuracy but a higher probability of safe zone placement in Crowe III/IV patients undergoing RaTHA [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Zhou et al. also observed no significant difference in cup angles but more cases within safe zones with RaTHA across Crowe types I-IV [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. This reflects the ability of experienced surgeons to achieve excellent manual placement on average, underscoring that technology cannot fully replace surgical expertise. Nevertheless, the reduced variability in the robotic group reinforces its role in enhancing reproducibility\u0026mdash;particularly valuable in complex anatomy.\u003c/p\u003e \u003cp\u003eNotably, despite reduced variability in cup positioning in the robotic group, two early dislocations occurred, both attributable to severe soft tissue deficiency from childhood septic arthritis sequelae. This highlights a fundamental limitation of current robotic systems (MAKO 3.0): planning is based solely on static bony anatomy, with no capacity to address dynamic soft tissue stability, which is crucial for postoperative hip function and prosthesis stability [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. This insight shifts the focus from purely technical precision to a more holistic approach, emphasizing that osseous accuracy alone may be insufficient in patients with significant soft tissue compromise.\u003c/p\u003e \u003cp\u003eComplication rates were low and comparable between groups, likely due to standardized perioperative protocols including antibiotic prophylaxis, multimodal thromboprophylaxis, and structured rehabilitation. Nerve traction symptoms occurred at similar rates, reflecting the inherent challenge of lengthening severely contracted limbs regardless of surgical technique [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSeveral limitations should be acknowledgment. The sample size, though substantial for this rare condition, remains modest. The non-blinded design and additional cost of robotics may have introduced selection and performance bias. Future research requires randomized controlled trials (RCTs) to eliminate such selection bias. Short-term follow-up precludes assessment of long-term implant survivorship, functional sustainability, or cost-effectiveness.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study suggested that RaTHA could be beneficial only for patients with severe hip dislocation accompanied by bony structural deformities. It could reduce variability in acetabular cup positioning and lower the risk of iatrogenic acetabular wall perforation, which might facilitate the early recovery of function. However, RaTHA did not demonstrate superior advantages over manual THA in terms of mean cup positioning, LLD control, or offset restoration, and was associated with increased operative time and costs.\u003c/p\u003e \u003cp\u003eA critical finding was the occurrence of dislocations in the robotic group despite improved cup consistency, underscoring the technology's current inability to address soft tissue instability and the irreplaceable role of surgical judgment in managing soft tissues. The clinical value of robotic assistance may be further enhanced by future developments that integrate dynamic soft tissue assessment into preoperative planning, allowing for the definition of individualized safe angles for prosthesis implantation.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability statement:\u0026nbsp;\u003c/strong\u003eAll the data in the study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding statement:\u0026nbsp;\u003c/strong\u003eThis work was supported by fundings for \u003cem\u003eClinical Trials from the Affiliated Drum Tower Hospital, Medical School of Nanjing University\u003c/em\u003e（2022-LCYJ-MS-21，2024-LCYJ-PY-82）and \u003cem\u003eNanjing Municipal Health Science and Technology Development Project\u003c/em\u003e（YKK24103）and \u003cem\u003eKey Project Supported by Medical Science and Technology Development Foundation, Nanjing Department of Health\u003c/em\u003e（YKK24103）.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u0026nbsp;\u003c/strong\u003eThis study adheres to the Declaration of Helsinki and was approved by the Ethics Committee of Nanjing Drum Tower Hospital (Approval No.:2022-448-01). Written informed consent was obtained from all patients after detailed explanation of the surgical procedure and research objectives.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest disclosure:\u0026nbsp;\u003c/strong\u003eThe authors declare no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthorship Contribution Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYu Zhang: Conceptualization, Methodology, Writing - Original Draft. Wentian Gao: Formal analysis, Investigation, Data Curation. Qiangqiang Li: Software, Validation, Visualization. Aikeremu Aierken: Resources, Investigation. Yao Yao: Investigation, Data Curation. Peng Sun: Data Curation, Software.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Yuejian Ding: Data Curation, Software. Qing Jiang: Supervision, Review, Project administration.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Dongyang Chen: Supervision, Funding acquisition, Project administration.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u0026nbsp;\u003c/strong\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eEsmaeili S, Ghaseminejad-Raeini A, Ghane G, et al (2024) Total Hip Arthroplasty in Patients Who Have Crowe Type IV Developmental Dysplasia of the Hip: A Systematic Review. The Journal of Arthroplasty 39:2645-2660.e19. https://doi.org/10.1016/j.arth.2024.05.031\u003c/li\u003e\n \u003cli\u003ePoursalehian M, Hassanzadeh A, Shafiei SH, Mortazavi SMJ (2025) Mid- to Long-Term Outcomes and Complications of Total Hip Arthroplasty in Patients Who Have Crowe IV Developmental Dysplasia of the Hip: A Systematic Review and Meta-Analysis. The Journal of Arthroplasty 40:530\u0026ndash;539. https://doi.org/10.1016/j.arth.2024.08.026\u003c/li\u003e\n \u003cli\u003eBerninger MT, Hungerer S, Friederichs J, et al (2019) Primary Total Hip Arthroplasty in Severe Dysplastic Hip Osteoarthritis With a Far Proximal Cup Position. The Journal of Arthroplasty 34:920\u0026ndash;925. https://doi.org/10.1016/j.arth.2019.01.032\u003c/li\u003e\n \u003cli\u003eHu H, Yang J-Z, Li L, et al (2024) [Application of high hip center technique in total hip arthroplasty in patients with Crowe typeⅡand Ⅲ developmental dysplasia of hip and severe hip osteoarthritis]. Zhongguo Gu Shang 37:166\u0026ndash;172. https://doi.org/10.12200/j.issn.1003-0034.20220382\u003c/li\u003e\n \u003cli\u003eQian H, Wang X, Wang P, et al (2023) Total Hip Arthroplasty in Patients with Crowe III / IV Developmental Dysplasia of the Hip: Acetabular Morphology and Reconstruction Techniques. Orthopaedic Surgery 15:1468\u0026ndash;1476. https://doi.org/10.1111/os.13733\u003c/li\u003e\n \u003cli\u003eStirling P, Viamont-Guerra M-R, Strom L, et al (2021) Does Cup Position at the High Hip Center or Anatomic Hip Center in THA for Developmental Dysplasia of the Hip Result in Better Harris Hip Scores and Revision Incidence? A Systematic Review. Clin Orthop Relat Res 479:1119\u0026ndash;1130. https://doi.org/10.1097/CORR.0000000000001618\u003c/li\u003e\n \u003cli\u003eMasson J-B, Foissey C, Bertani A, et al (2023) Transverse subtrochanteric shortening osteotomy with double tension-band fixation during THA for Crowe III-IV developmental dysplasia: 12-year outcomes. Orthopaedics \u0026amp; Traumatology: Surgery \u0026amp; Research 109:103684. https://doi.org/10.1016/j.otsr.2023.103684\u003c/li\u003e\n \u003cli\u003eKanda A, Obayashi O, Mogami A, et al (2024) Total hip arthroplasty with subtrochanteric femoral shortening osteotomy using a monoblock cylindrical cementless stem for severe developmental hip dysplasia (Crowe type III, IV). SICOT-J 10:34. https://doi.org/10.1051/sicotj/2024032\u003c/li\u003e\n \u003cli\u003eShen X, Zhang R, Mei J, et al (2024) Total Hip Arthroplasty Combined with Proximal Femoral Reconstruction Effectively Treats Severe Hip Deformities: A Novel Osteotomy Technique. Orthopaedic Surgery 16:1939\u0026ndash;1945. https://doi.org/10.1111/os.14136\u003c/li\u003e\n \u003cli\u003eLan Y, Feng E, Lin B, et al (2022) Direct anterior versus posteriorlateral approachs for clinical outcomes after total hip arthroplasty in the treatment of severe DDH. BMC Musculoskelet Disord 23:958. https://doi.org/10.1186/s12891-022-05759-y\u003c/li\u003e\n \u003cli\u003eLiu Z, Bell CD, Ong AC, et al (2021) Clinical evaluation of direct anterior approach total hip arthroplasty for severe developmental dysplasia of the hip. Sci Rep 11:8105. https://doi.org/10.1038/s41598-021-87543-x\u003c/li\u003e\n \u003cli\u003eShen J, Zhou Y, Sun J, et al (2020) [Revision reasons and prosthesis selection of Crowe Ⅳ developmental dysplasia of hip after total hip arthroplasty]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 34:557\u0026ndash;562. https://doi.org/10.7507/1002-1892.201909015\u003c/li\u003e\n \u003cli\u003eRajan T, Garde A, Lavu MS, et al (2025) Total hip arthroplasty outcomes for developmental dysplasia of the hip versus primary osteoarthritis: Older age increases medical, not surgical complications. Journal of Clinical Orthopaedics and Trauma 69:103157. https://doi.org/10.1016/j.jcot.2025.103157\u003c/li\u003e\n \u003cli\u003eTaheriazam A, Poursaleh E, Abbaszadeh A, et al (2025) Nerve palsy following total hip arthroplasty using trochanteric osteotomy and proximal femoral shortening in Crowe Type 4 developmental dysplasia of the hip: a prospective cohort study. BMC Musculoskelet Disord 26:776. https://doi.org/10.1186/s12891-025-09012-0\u003c/li\u003e\n \u003cli\u003eShanaa J, Bernstein E, Shanaa N, et al (2025) Balancing Risk and Reward in Hip Resurfacing for Developmental Dysplasia of the Hip: A Systematic Review and Meta-Analysis. JBJS Reviews 13:. https://doi.org/10.2106/JBJS.RVW.25.00091\u003c/li\u003e\n \u003cli\u003eZhang Y, Wang Z, Yuan J, et al (2025) Impact of Robotic-Assisted Technology on Joint Awareness Following Total Joint Arthroplasty: A Systematic Review and Meta-Analysis. The Journal of Arthroplasty S0883540325010290. https://doi.org/10.1016/j.arth.2025.08.024\u003c/li\u003e\n \u003cli\u003eZhang Y, Li S, Liu X, et al (2025) Robot-Assisted Total Hip Arthroplasty Versus Conventional Surgery in Terms of Surgical Accuracy, Function, Trauma, and Complications: A Prospective, Multicenter, Parallel-Group, Open-Label Randomized Controlled Trial. The Journal of Arthroplasty S0883540325008927. https://doi.org/10.1016/j.arth.2025.07.029\u003c/li\u003e\n \u003cli\u003eHahn AK, Bauer JA, Megalla M, Grosso MJ (2025) Dislocation Rates Between Manual and Robotic-Assisted Total Hip Arthroplasty Using the Posterolateral Approach. J Am Acad Orthop Surg. https://doi.org/10.5435/JAAOS-D-24-01502\u003c/li\u003e\n \u003cli\u003eHowell C, Witvoet S, Scholl L, et al (2025) Postoperative Complications and Readmission Rates in Robotic-Assisted and Manual Total Hip Arthroplasty: A Large, Multi-Hospital Study. Medical Care 63:465\u0026ndash;471. https://doi.org/10.1097/MLR.0000000000002082\u003c/li\u003e\n \u003cli\u003eZhang X, Shen X, Zhang R, et al (2024) Radiographic evaluation of robot-assisted versus manual total hip arthroplasty: a multicenter randomized controlled trial. J Orthop Traumatol 25:33. https://doi.org/10.1186/s10195-024-00773-3\u003c/li\u003e\n \u003cli\u003eLim PL, Gonzalez MR, Wang KY, et al (2025) Does Robotic Assistance Increase the Likelihood of Achieving the Minimal Clinically Important Improvement Following Total Hip Arthroplasty? Findings From a Propensity Score Matched Analysis of 1,364 Procedures. The Journal of Arthroplasty S0883540325005108. https://doi.org/10.1016/j.arth.2025.05.015\u003c/li\u003e\n \u003cli\u003eZepeda KE, Burgio C, Karasavvidis T, et al (2025) Impact of Robotic Assistance on Total Hip Arthroplasty: Granular Insights Into Surgical Time. The Journal of Arthroplasty 40:S172\u0026ndash;S178. https://doi.org/10.1016/j.arth.2025.03.068\u003c/li\u003e\n \u003cli\u003eSacher SE, A. O\u0026rsquo;Donnell J, Wright TM, et al (2025) Robotic-Assisted Surgery Does Not Decrease Prosthetic Impingement in Total Hip Arthroplasty: A Retrieval Analysis. The Journal of Arthroplasty 40:S333\u0026ndash;S337. https://doi.org/10.1016/j.arth.2025.02.077\u003c/li\u003e\n \u003cli\u003eShi H, Yu R, Pu L, et al (2025) Application and exploration of total hip arthroplasty for developmental dysplasia of the hip assisted by full-process robotics. BMC Musculoskelet Disord 26:225. https://doi.org/10.1186/s12891-025-08460-y\u003c/li\u003e\n \u003cli\u003eGuo D, Li X, Ma S, et al (2022) Total Hip Arthroplasty with Robotic Arm Assistance for Precise Cup Positioning: A Case‐Control Study. Orthopaedic Surgery 14:1498\u0026ndash;1505. https://doi.org/10.1111/os.13334\u003c/li\u003e\n \u003cli\u003eXu S, Bernardo L, Yew K, Pang H (2020) Robotic-Arm Assisted Direct Anterior Total Hip Arthroplasty; Improving Implant Accuracy. Surg Technol Int PMID: 33368137. https://doi.org/10.52198/21.STI.38.OS1368\u003c/li\u003e\n \u003cli\u003eBensa A, Pagliazzi G, Miele A, et al (2025) Robotic-Assisted Total Hip Arthroplasty Provides Greater Implant Placement Accuracy and Lower Complication Rates, but Not Superior Clinical Results Compared to the Conventional Manual Approach: A Systematic Review and Meta-Analysis. The Journal of Arthroplasty 40:1921\u0026ndash;1931. https://doi.org/10.1016/j.arth.2024.12.014\u003c/li\u003e\n \u003cli\u003eZora H, Bayrak G, Bilgen \u0026Ouml;F (2025) Robotically Assisted vs. Manual Total Hip Arthroplasty in Developmental Hip Dysplasia: A Comparative Analysis of Radiological and Functional Outcomes. JCM 14:509. https://doi.org/10.3390/jcm14020509\u003c/li\u003e\n \u003cli\u003eChai W, Xu C, Guo R-W, et al (2022) Does robotic-assisted computer navigation improve acetabular cup positioning in total hip arthroplasty for Crowe III/IV hip dysplasia? A propensity score case-match analysis. International Orthopaedics (SICOT) 46:769\u0026ndash;777. https://doi.org/10.1007/s00264-021-05232-w\u003c/li\u003e\n \u003cli\u003eSato K, Sato A, Okuda N, et al (2022) A propensity score-matched comparison between Mako robotic arm-assisted system and conventional technique in total hip arthroplasty for patients with osteoarthritis secondary to developmental dysplasia of the hip. Arch Orthop Trauma Surg 143:2755\u0026ndash;2761. https://doi.org/10.1007/s00402-022-04524-z\u003c/li\u003e\n \u003cli\u003eZhou Y, Shao H, Huang Y, et al (2021) Does robotic assisted technology improve the accuracy of acetabular component positioning in patients with DDH? J Orthop Surg (Hong Kong) 29:23094990211025325. https://doi.org/10.1177/23094990211025325\u003c/li\u003e\n \u003cli\u003eRoss D, Erkocak O, Rasouli MR, Parvizi J (2019) Operative Time Directly Correlates with Blood Loss and Need for Blood Transfusion in Total Joint Arthroplasty. Arch Bone Jt Surg 7:229\u0026ndash;234\u003c/li\u003e\n \u003cli\u003eBoucher M, Tremblay J, Pelet T, et al (2025) Topical Versus Systemic Tranexamic Acid to Reduce Blood Loss After Total Knee and Total Hip Arthroplasty: A Systematic Review and Meta-Analysis. Journal of Bone and Joint Surgery. https://doi.org/10.2106/JBJS.24.01511\u003c/li\u003e\n \u003cli\u003eZhang Q, Yin S, Huang K, et al (2021) [Effectiveness and safety of tranexamic acid combined with intraoperative controlled hypotension on reducing perioperative blood loss in primary total hip arthroplasty]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 35:1133\u0026ndash;1140. https://doi.org/10.7507/1002-1892.202103230\u003c/li\u003e\n \u003cli\u003eAndo W, Takao M, Hamada H, et al (2021) Comparison of the accuracy of the cup position and orientation in total hip arthroplasty for osteoarthritis secondary to developmental dysplasia of the hip between the Mako robotic arm-assisted system and computed tomography-based navigation. International Orthopaedics (SICOT) 45:1719\u0026ndash;1725. https://doi.org/10.1007/s00264-021-05015-3\u003c/li\u003e\n \u003cli\u003eByeon N, Shin J, Kim S, et al (2025) Comparative Study of the Rehabilitation Exercise 5R System and Aerobic Exercise on Postpartum Recovery: Impacts on Muscle Function and Metabolic Health. Med Sci Monit 31:. https://doi.org/10.12659/MSM.947877\u003c/li\u003e\n \u003cli\u003eTaheriazam A, Baghbani S, Malakooti M, et al (2024) Neuromonitoring in pre-post and intraoperative total hip replacement surgery in type 4 high-riding developmental dysplasia of the hip. European Review for Medical and Pharmacological Sciences 28:98\u0026ndash;106. https://doi.org/10.26355/eurrev_202401_34895\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Hip dislocation, Total hip arthroplasty, Robot-assisted, Manual technique","lastPublishedDoi":"10.21203/rs.3.rs-8512197/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8512197/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eSevere hip dislocation caused by various reasons poses significant challenges to total hip replacement(THA)surgery. The application value of robot-assisted THA in such diseases is still unclear. This propensity score-matched study aimed to compare the early outcomes of robot-assisted THA (RaTHA) versus manual THA (MTHA) in patients with severe hip dislocations (Crowe type III/IV).\u003c/p\u003e\u003cp\u003e\u003cb\u003ePatients and Methods\u003c/b\u003e\u003c/p\u003e \u003cp\u003ePatients undergoing THA for severe dislocations were prospectively enrolled, and thier data were collected. Using propensity score matching (based on age, sex, BMI, Crowe classification, and comorbidities), patients were allocated into matched RaTHA and MTHA cohorts. The groups were compared at 12 months postoperatively regarding perioperative indicators, radiographic assessments, functional outcomes (Harris Hip Score, HHS), and complication rates.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eAfter matching, 29 MTHA and 33 RaTHA patients were finally analyzed. RaTHA was associated with a significantly longer operative time (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.042), longer preoperative length of stay (LOS)(\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032), and higher hospitalization costs (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008) compared to MTHA. Postoperative LOS was similar between the groups. Preoperative HHS were comparable, whereas the RaTHA group showed no significantly higher HHS at 12 months postoperatively (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.081). The variability in cup positioning (standard deviation) was lower in the RaTHA group for both inclination (4.7\u0026deg; vs. 8.1\u0026deg;) and anteversion (4.6\u0026deg; vs. 8.6\u0026deg;). However, no statistically significant differences were observed in mean cup inclination or anteversion angles, limb length discrepancy (LLD), or femoral and acetabular offset gaps (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Regarding complications, two patients in the RaTHA group experienced dislocations at 3 or 4 months postoperatively, while six patients in the MTHA group had iatrogenic acetabular defects. Both groups reported two cases of postoperative symptoms of femoral nerve palsy.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e \u003cp\u003eFor complex and anatomically variable bone structures, robotic technology offered an advantage in procedural consistency, effectively reducing the risk of excessive bone loss. Nevertheless, its impact on shortly functional outcomes, dislocation rates, and economic burden did not currently support a definitive recommendation for its widespread use.\u003c/p\u003e\u003cp\u003e\u003cb\u003eLevel of evidence\u003c/b\u003e\u003c/p\u003e \u003cp\u003eLevel Ⅱ.\u003c/p\u003e","manuscriptTitle":"How Much Benefit Can Robot-Assisted Total Hip Arthroplasty Provide for Patients with Severe Hip Dislocation? -a Propensity Score-Matched Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-11 06:36:19","doi":"10.21203/rs.3.rs-8512197/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b9fa32d2-c882-4bec-bf78-81ab88643f03","owner":[],"postedDate":"February 11th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-10T07:41:45+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-11 06:36:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8512197","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8512197","identity":"rs-8512197","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}