Comparison of Anterior and Posterior Approaches for Hip Resurfacing Arthroplasty: A Gait Analysis Study

Comparison of Anterior and Posterior Approaches for Hip Resurfacing Arthroplasty: A Gait Analysis Study | 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 Comparison of Anterior and Posterior Approaches for Hip Resurfacing Arthroplasty: A Gait Analysis Study Milos Brkljac, Amy Maslivec, Natasha Allott, Kartik Logishetty, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7251168/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 02 Dec, 2025 Read the published version in Journal of Orthopaedic Surgery and Research → Version 1 posted 9 You are reading this latest preprint version Abstract Background: Hip resurfacing arthroplasty (HRA) is commonly performed using the posterior approach (POS), which is familiar to most surgeons and allows excellent exposure. The short external rotators and often the gluteus maximus are incised with the POS, which may adversely affect gait. The direct anterior approach (DAA), which is muscle sparing has been shown to preserve more physiological gait patterns in total hip arthroplasty. This study aims to compare outcomes between POS and DAA approaches using gait analysis, the Oxford Hip Score (OHS), Metabolic Equivalent of Task (MET), and EQ-5D. Methods: Seventeen unilateral DAA and 17 POS HRA males were matched for age and BMI. Patients underwent instrumented treadmill gait analysis and completed patient reported outcome scores (PROMs) at a mean of 1.5 (0.9–1.8) years post-operatively. Kinematics and kinetics were recorded using motion capture and force plate data. Group differences were assessed using statistical parametric mapping. These data were compared to a group of 19 healthy male controls matched for age and BMI. Results: Gait analysis postoperatively revealed no significant differences in hip kinematics in either the coronal or sagittal planes between the posterior and direct anterior approaches. Statistical parametric mapping showed no differences in vertical ground reaction forces across the stance phase. Spatiotemporal gait parameters, including top walking speed, cadence, step length, and step width, were comparable between groups and closely aligned with healthy controls. Both cohorts achieved similar postoperative OHS (mean:48, p = 0.651), EQ-5D (median:1.0, p = 0.786), and MET scores (POS:13.1 vs DAA:12.6, p=0.856). Conclusions : This is the first study to analyse gait following HRA via the DAA. Both DAA and POS restored normal gait patterns, with no significant differences in kinematics, kinetics, or spatiotemporal parameters, and results comparable to matched healthy controls. PROMSs were similarly excellent across groups indicating high functional recovery and engagement in moderate-to-vigorous physical activity. Anterior Approach Posterior Approach Hip Resurfacing Hip Arthroplasty Gait Analysis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction The functional demands on hip arthroplasty patients continue to rise. This trend reflects the procedure’s success and implant longevity, making it a viable option for individuals in their 40s and 50s [ 1 ]. Consequently, younger high-demand patients often opt for hip resurfacing due to its reported superiority in functional outcomes. [ 2 – 4 ]. Currently available Metal-on-Metal (MoM) designs retain some controversy due to adverse reactions to metal wear debris. However, excellent results exist when performed well and using proven designs, such as the Birmingham Hip Resurfacing (BHR) [ 5 ]. More recently, promising early results [ 6 ] with ceramic-on-ceramic (CoC) bearings suggest a likely resurgence of interest in hip resurfacing. As hip resurfacing gains popularity, the surgical approach for this technically demanding procedure will face increasing scrutiny. Crucially, its impact on recovery and functional outcomes must be carefully evaluated. Treadmill gait analysis provides an objective measure of functional performance, enabling quantitative assessment of walking at both normal and high speeds. This more sophisticated measure of function demonstrates symmetrical gait in healthy individuals, while osteoarthritic patients exhibit notable asymmetries. Total hip arthroplasty (THA) improves gait symmetry, however only HRA has been shown to restore physiological gait at higher walking speeds [ 7 ]. Both CoC HRA and the MoM BHR have been shown to restore gait parameters nearly indistinguishable from healthy controls [ 8 , 9 ]. Despite an often more extensive exposure it is unclear why HRA patients walk more normally than those undergoing THA. Normal walking is considered a prerequisite for more demanding activities, such as running, jumping, and sport [ 10 , 11 ]. Historically, the success of hip arthroplasty has been assessed predominantly using patient-reported outcome measures (PROMs), which are limited by ceiling effects in high-functioning patients. More recently, the metabolic equivalent of task (MET) score has been proposed as an alternative, offering a patient-centred, normally distributed measure of postoperative physical activity intensity that better captures higher-level functional recovery. The MET reflects engagement in moderate-to-vigorous physical activity, aligning with the expectations and health goals of younger, active patients. The anterior approach is often preferred by patients seeking high functional recovery, and when combined with hip resurfacing arthroplasty, may offer additive benefits for this cohort. There are limited published studies describing HRA performed through an anterior approach [ 12 – 17 ]. The posterior approach (POS) remains popular due to its familiarity among surgeons and the excellent exposure it provides of both the acetabulum and femur. Modifications to this technique have enhanced femoral head access while preserving the ascending branch of the medial femoral circumflex artery [ 18 ]. By retaining the anastomoses around the greater trochanter and the retinacular vessels around the femoral neck the risk of avascular necrosis (AVN) can be reduced. AVN has been shown to be a cause for early femoral neck fractures, alongside notching, incomplete seating and varus alignment of the femoral component [ 19 ]. Despite these modifications the posterior approach sacrifices the short external rotators and may carry a higher dislocation rate than others [ 20 ]. In contrast, the direct anterior approach (DAA) is muscle-sparing and has been associated with more physiological gait patterns, potentially offering functional advantages. [ 21 ]. To date, DAA has been associated with improved gait outcomes after THA during the early postoperative period (6–12 weeks) and at one year following surgery, compared to the posterior approach [ 22 , 23 ]. However, a meta-analysis comparing DAA to the lateral (LAT) approach found no clinically meaningful differences in gait beyond three months [ 24 ]. The considerable heterogeneity in gait analysis methods across studies complicates meaningful comparison and data synthesis. Notably, no studies have specifically investigated gait outcomes following HRA using the anterior approach. Objectives The primary aim was to evaluate the impact of surgical approach on gait biomechanics in high-functioning patients one year after hip resurfacing arthroplasty, compared with a healthy control group. The secondary aim was to examine differences in metabolic equivalent of task (MET) scores across the two groups. Methods Study population Thirty-four male patients who had received a unilateral MoM hip resurfacing (Birmingham Hip Resurfacing, Smith & Nephew) were selected for this study from a longitudinal study of gait (ethics reference number 14/NS/1045). Patients had either a direct anterior (DAA, n = 17) or a posterior (POS, n = 17) approach to surgery by the same surgeon. Exclusion criteria included a BMI greater than 40, over 70 years old or having severe comorbidities. All patients required unilateral HRA, they had no osteoarthritis (OA) or other surgery of their contralateral limb and were able to complete a gait analysis assessment 12 months post-operatively. Eighteen healthy control volunteers (CON) were matched for age, sex, and BMI, if they had no evidence of hip or knee osteoarthritis, no history of hip or knee surgery or injury, or any other lower limb dysfunction (Table 1 ). Table 1 Patient Demographics by Surgical Approach and Control Group POS (n = 17) DAA (n = 17) CON (n = 17) Age (Years) 51 (47–61) 55 (47–60) 42 (40–62) BMI (kg/m²) 25 (2) 26 (2) 26 (4) Time Postop (Years) 1.1 (1.0-1.2) 1.2 (1.1–1.3) - Data are presented as median (interquartile range, IQR) for age and time from surgery to assessment, and mean (standard deviation, SD) for body mass index (BMI). POS = posterior approach; DAA = direct anterior approach; CON = control group. Patient Reported Outcome Measures (PROMs) The Oxford Hip Score (OHS), EQ5D, and Metabolic Equivalent of Task Score (MET) were completed post-operatively. The MET score was calculated using the same methodology to Edwards et al. [ 25 ]. Gait Protocol All patients underwent treadmill gait analysis post-operatively (0.9–1.3 years) using an instrumented treadmill [ 9 ] (HP/COSMOS, Hab International). The vertical components of ground reaction forces (GRF) were collected on tandem force plates (1000Hz). After 5 minutes of familiarisation walking at 3km/hr, the speed of the treadmill was increased to 4 km/hr then further increased by 0.5 km/hr every 60 seconds until the patient reached their self-determined top walking speed (TWS). Patients wore their own comfortable footwear and were secured in a safety harness throughout the analysis and were able to stop at any point. A 3D motion-capture system (200Hz, VICON Nexus, Oxford Metrics Ltd, Oxford, UK) with 34 anatomically placed body markers on the lower extremities and pelvis was used to record kinematic data[ 26 ]. Data analyses Data was collected during a 30 second period at each walking speed, and the average of 10 steps for each limb was used for further analysis. GRF was normalised to body weight and were time normalised to 100% of the stance phase of the gait cycle. For kinematic data, the 3D marker trajectories were collected at 100 Hz with a 10-camera 3D motion capture system and was time normalised to 100% of the gait cycle and processed in VICON nexus. All data was analysed using custom Matlab scripts (Version 2022a, The Mathworks Inc., United States). Spatiotemporal gait variables Top walking speed (TWS), cadence, step length of the operated limb, and step width were recorded. TWS was determined as the fastest walking speed achieved before breaking out into a run or being limited by discomfort. Ground Reaction Force Profile Vertical GRFs profiles were collected during the stance phase of the gait cycle and reported at 6 km/hr as this was the highest common walking speed. Kinematic data Hip angle in the sagittal and coronal plane was collected over the gait cycle. The angle values were ‘zeroed’ to 30 for sagittal, and 0 for coronal, to allow for a better comparison in range of motion, and do not therefore depict absolute hip angle [ 11 ]. Statistical Analysis All data were assessed for normality using the Shapiro–Wilk test. Parametric tests were applied to normally distributed datasets, while non-parametric tests were used for non-normally distributed data. Between-group comparisons for the Oxford Hip Score (OHS) and EQ-5D were conducted using the Mann–Whitney U test, while the MET score was compared using an independent samples t-test. For spatiotemporal gait parameters, ground reaction forces (GRF), and joint kinematics, either one-way analysis of variance (ANOVA) or the Kruskal–Wallis test was used, depending on the distribution of each dataset. For time-continuous data such as GRF and hip joint angles over the stance phase, statistical parametric mapping (SPM) was employed. SPM conducts t-tests across the entire normalised time series (0–100% of stance), identifying regions where the test statistic exceeds the critical threshold corresponding to p < 0.05. These regions were considered statistically significant. Results Patient Demographics Patient demographics are presented in Table 1. The median age (IQR) was 51 (47–61) years in the POS group, 55 (47–60) years in the DAA group, and 42 (40–62) years in the Control group. A Kruskal–Wallis test showed no statistically significant difference in age between the groups (p = 0.517). Body mass index (BMI) was also comparable across groups, with mean values of 25 (POS), 26 (DAA), and 26 (controls), showing no significant difference using one-way ANOVA (p = 0.517). Similarly, the time from surgery to assessment did not differ significantly between the surgical groups, with a median of 1.1 years for POS and 1.2 years for DAA (Mann–Whitney U test, p = 0.061). No patients had undergone revision surgery or reoperation at the time of writing. Patient Reported Outcome Measures The postoperative scores are demonstrated in figures 1,2 and 3. No significant differences were observed between the postoperative scores for POS and DAA groups respectively for the Oxford Hip Score (OHS: 48 vs. 48, p = 0.651), EQ-5D (1 vs. 1, p = 0.786), or MET score (13.1 vs. 12.6, p = 0.856). Spatiotemporal Gait Parameters Patient walking characteristics are presented in table 2. A one-way ANOVA revealed no significant differences between the groups for normalized top walking speed (F(2,48) = 1.83, p = 0.833), step length (F(2,48) = 4.23, p = 0.523), cadence (F(2,48) = 1.83, p = 0.411), or step width (F(2,48) = 2.98, p = 0.375). A Kruskal–Wallis test showed no significant differences in top walking speed (TWS; χ²(2) = 10.084, p = 0.08). Table 2 . Walking Characteristics by Surgical Approach and Control Group POS DAA CON TWS (km/hr) 7.5 (6-8) 7 (6.5-8) 7.5 (6-7.5) TWSnorm 0.66 (0.04) 0.65 (0.05) 0.64 (0.1) Step Length (cm) 94 (3) 94 (2) 95 (2) Cadence 104 (3) 103 (2) 104 (2) Step Width 8 (2) 9 (2) 10 (1) Data are presented as median (interquartile range, IQR) for top walking speed (TWS), and mean (standard deviation, SD) for all other spatiotemporal variables. TWSnorm = normalised top walking speed; POS = posterior approach; DAA = direct anterior approach; CON = control group. Ground Reaction Force Profile SPM analysis detected no significant differences (p=<0.05) in ground reaction force (GRF) across the stance phase between the POS and DAA groups when compared at 6 km/hr against healthy controls, figure 4. Hip Range of Motion Analysis of hip joint kinematics revealed no statistically significant differences in range of motion between POS and DAA approaches across the gait cycle in either the coronal or sagittal planes. In the coronal plane (figure 5), both groups exhibited similar patterns of adduction and abduction, with a peak difference of approximately 2 degrees and the SPM{t} statistic remaining below the critical threshold (t* = 3.613, α = 0.05) throughout the gait cycle. In the sagittal plane (figure 6), while slight variations were observed—particularly with the DAA group showing marginally greater peak extension—the SPM{t} curve again remained below the critical threshold (t* = 3.202, α = 0.05), indicating no statistically significant difference. Both resurfacing groups demonstrated similar motion profiles overall. Discussion The primary finding is that at 1 year postop, patients undergoing HRA demonstrate gait which is comparable to age-matched healthy controls, regardless of surgical approach. Secondary finding is that HRA delivers excellent PROMs — maximal OHS, and a MET score averaging 13, which equates to the ability to perform high-intensity activities such as running, vigorous cycling, or competitive sports, reflecting exceptional functional capacity postoperatively. Our findings align with previous studies analysing spatiotemporal variables, demonstrating that HRA can restore near-physiological gait [ 8 , 9 ]. Furthermore, this study is the first to assess multiplanar hip angle kinematics using SPM throughout the gait cycle, showing restoration to near-normal levels following resurfacing with either approach. A comparable study [ 23 ] investigated the three most commonly utilised surgical approaches to the hip— DAA, POS, and LAT—in the context of total hip arthroplasty. Ryan et al. found that the DAA and lateral approaches resulted in more favourable sagittal and frontal plane gait kinematics compared to the posterior approach. Only the DAA group demonstrated spatiotemporal parameters within the normal range. Notably, their DAA cohort exhibited evidence of hip abductor unloading during the loading response phase—a pattern not observed in our study. These findings suggest that the choice of arthroplasty type (HRA vs THA) may have a greater influence on postoperative gait biomechanics than surgical approach alone. The mechanisms underlying the ability of hip resurfacing to restore more normal gait remain unclear. To date, one Randomised Controlled Trail (RCT) [ 7 ] has described its superiority over THA, particularly at higher walking speeds. However, this was not replicated in other trials [ 27 ], with Lavigne et al. [ 28 ] concluding that large-head THA provides the same benefit to restoring gait as HRA. Their trial may have been inadequately powered [ 29 ], however, it points to head size as a potential determinant. In a biomechanical study [ 30 ] conducted in our lab restoring native head size when combined with capsular repair restored tension to the ligaments which were able to wrap around the head. Conversely, THA with a 32mm head left the capsule slack thus defunctioning the capsule. Interestingly, an article comparing gait parameters across different head sizes found that a larger head size (36 mm) improved gait patterns [ 31 ] at a mean of 3.5 years postoperatively. Longer-term functional benefits of larger head sizes (36-44mm) have also been described using the UCLA score at five years [ 32 ]. At higher activity levels such as fast walking or running, peak hip stresses can reach seven times body weight [ 33 ]. The resulting load transfer to the proximal femur is greatly impacted by head size, but equally the choice of materials and the presence of metalwork extending into the medullary canal. HRA has been shown to preserve native proximal femoral elasticity [ 34 , 35 ] however, these findings are based on studies of now-withdrawn implants. The influence of fixation method, femoral stem size, and materials on proximal femoral elasticity, particularly with emerging CoC HRA, remains understudied. A limitation of our study is that it offers only a snapshot of data at one year postoperatively. DAA has been shown to offer a faster postoperative functional recovery, and a resulting shorter hospital stay compared to POS [ 36 ]. It is therefore possible that a faster recovery trajectory in the DAA cohort was not captured. Similarly, the lack of pre-operative data limits baseline comparisons and precludes assessment of preoperative impairment severity on postoperative outcomes. We are however reassured by the fact our patients reached the levels of healthy controls despite suffering with debilitating osteoarthritis preoperatively. Furthermore, only male patients were included, as female sex is considered a contraindication for MoM HRA. While the lack of randomisation introduces a risk of selection bias, robust demographic matching across the three groups was employed. Strengths of our study include prospective data collection, complete postoperative hip scores, along with a personalised assessment of physical activity (PA) based on the MET score [ 25 ]. Objective functional measures, such as gait analysis, are crucial in evaluating arthroplasty outcomes, as limited walking speed often indicates reduced capacity for high-demand physical activities [ 10 ]. Additionally, a more normal gait reduces fall risk in older patients [ 37 ]. As physical function improves, patients may be better able to engage in moderate-to-vigorous physical activity (MVPA), which is strongly associated with reduced cardiometabolic disease risk and lower all-cause mortality [ 38 , 39 ]. In line with this, current WHO guidelines recommend that adults maintain 150–300 minutes of moderate-intensity aerobic or at least 75–150 minutes of vigorous-intensity [ 40 ]. This equates to between 450–900 Metabolic Equivalent of Task (MET) minutes. In our study, postoperative MET scores for POS (13.1) and DAA (12.6) showed no significant difference between approaches but indicated engagement in MVPA, reflecting high functional recovery. Crucially, the MET score mitigated the ceiling effect of the OHS by capturing higher levels of physical activity that were previously undetectable, as demonstrated in Figs. 1 and 2 . The direct anterior approach appeals to both surgeons and patients by minimising muscular damage and facilitating rapid recovery, making it particularly attractive for high-demand patients, often the same cohort as resurfacing candidates. However, while early discharge may offer economic benefits, these may be offset by the higher cost of DAA compared to the posterior approach [ 41 ]. Despite excellent outcomes in specialist centres [ 12 ], an additional learning curve exists even for experienced DAA surgeons when adapting the approach for resurfacing. Balancing adequate exposure, femoral mobility, and capsular blood supply preservation is achievable but influenced by patient factors [ 42 ]. When performed safely, DAA complements hip resurfacing in high-demand patients, supporting the restoration of function to levels enabling high-intensity health enhancing PA. Future studies should incorporate randomisation, preoperative gait analysis, and postoperative activity tracking via accelerometers at multiple time points to determine whether one approach offers superior outcomes. Conclusions This study is the first to demonstrate equivalent gait outcomes between the anterior and posterior approaches for HRA, with both restoring normal patterns. While no differences were observed between DAA and POS, both approaches yielded successful outcomes in this high-functioning cohort. Abbreviations AHI Acromiohumeral interval ASES American Shoulder and Elbow Surgeons AUC Area under the curve CHL Coracohumeral ligament ISP Infraspinatus LHB Long head of the biceps MCID Minimal clinically important difference MRI Magnetic resonance imaging RCTs Rotator cuff tears RI Rotator interval ROC Receiver operating characteristic ROM Range of motion SGHL Superior glenohumeral ligament SSC Subscapularis SSP Supraspinatus VAS Visual analog scale HRA Hip resurfacing arthroplasty POS Posterior approach DAA Direct anterior approach OHS Oxford Hip Score MET Metabolic Equivalent of Task EQ-5D EuroQol-5 Dimensions PROMs Patient-reported outcome measures MoM Metal-on-metal BHR Birmingham Hip Resurfacing CoC Ceramic-on-ceramic THA Total hip arthroplasty LAT Lateral approach OA Osteoarthritis BMI Body mass index CON Control group GRF Ground reaction force TWS Top walking speed TWSnorm Normalised top walking speed SPM Statistical parametric mapping KDE Kernel density estimate RCT Randomised controlled trial PA Physical activity MVPA Moderate-to-vigorous physical activity WHO World Health Organization UK United Kingdom SD Standard deviation IQR Interquartile range ANOVA Analysis of variance MATLAB Matrix Laboratory (software used for data analysis) Declarations Consent for publication : All authors have read and agreed to the published version of the manuscript. Availability of data and materials : The datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests : The authors declare no competing interests. Funding : No funding was received to support the conduct of this study or the preparation of this manuscript. Acknowledgements: We acknowledge the contribution of Rima Nasser in helping identify the patients who had undergone surgery to be included in the study. Ethics statement : This study was approved by our local ethics committee (ethics reference number 14/NS/1045). References Ekhtiari S, Sefton AK, Wood TJ, Petruccelli DT, Winemaker MJ, de Beer JD. The Changing Characteristics of Arthroplasty Patients: A Retrospective Cohort Study. J Arthroplasty. 2021;36(7):2418-23. Morse KW, Premkumar A, Zhu A, Morgenstern R, Su EP. Return to Sport After Hip Resurfacing Arthroplasty. Orthop J Sports Med. 2021;9(5):23259671211003521. 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Direct anterior approach has short-term functional benefit and higher resource requirements compared with the posterior approach in primary total hip arthroplasty : a meta-analysis of functional outcomes and cost. Bone Joint J. 2021;103-B(6):1078-87. Karunaseelan KJ, Nasser R, Jeffers JRT, Cobb JP. Optimal hip capsular release for joint exposure in hip resurfacing via the direct anterior approach. Bone Joint J. 2024;106-B(3 Supple A):59-66. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 02 Dec, 2025 Read the published version in Journal of Orthopaedic Surgery and Research → Version 1 posted Editorial decision: Revision requested 27 Sep, 2025 Reviews received at journal 14 Sep, 2025 Reviewers agreed at journal 20 Aug, 2025 Reviews received at journal 19 Aug, 2025 Reviewers agreed at journal 18 Aug, 2025 Reviewers invited by journal 18 Aug, 2025 Editor assigned by journal 31 Jul, 2025 Submission checks completed at journal 31 Jul, 2025 First submitted to journal 30 Jul, 2025 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. 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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-7251168","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":502949096,"identity":"c5ad9d96-4fcd-4690-a5b4-5336c17509f5","order_by":0,"name":"Milos Brkljac","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxklEQVRIiWNgGAWjYDACCQZmhgc8DAz8zHABYrQkALVINpOmBUgbHCBWi+7s3scGCTJ28sbHmR8w/KhhSJzZQECL2Z3jxgkJPMmG2w6zGTD2HGNInE3IFrMbacwHEniYE8wOAz3E28CQOI9ILfUJxs08DIx/idUCdNjhBANmHgZmkC2EHXbnGLNBAs9xwxlAvxyWOSZhTNj7t9uYJT72VMvz9x9++PBNjY3sjAOErAEBxh4IfYCYiISCH8QqHAWjYBSMghEJAD+MOVpsabNhAAAAAElFTkSuQmCC","orcid":"","institution":"Imperial College London","correspondingAuthor":true,"prefix":"","firstName":"Milos","middleName":"","lastName":"Brkljac","suffix":""},{"id":502949098,"identity":"1e6cb49f-973f-496e-aca3-a7215047d8d4","order_by":1,"name":"Amy Maslivec","email":"","orcid":"","institution":"Imperial College London","correspondingAuthor":false,"prefix":"","firstName":"Amy","middleName":"","lastName":"Maslivec","suffix":""},{"id":502949099,"identity":"41287d6b-dae0-4aac-89f5-2227b5cab52f","order_by":2,"name":"Natasha Allott","email":"","orcid":"","institution":"Imperial College London","correspondingAuthor":false,"prefix":"","firstName":"Natasha","middleName":"","lastName":"Allott","suffix":""},{"id":502949102,"identity":"7f229497-fec1-4d7e-884a-dda1aabc1d54","order_by":3,"name":"Kartik Logishetty","email":"","orcid":"","institution":"University College London","correspondingAuthor":false,"prefix":"","firstName":"Kartik","middleName":"","lastName":"Logishetty","suffix":""},{"id":502949103,"identity":"ea52c7ad-94ac-459d-bae3-95f8aac0f62b","order_by":4,"name":"Justin Cobb","email":"","orcid":"","institution":"Imperial College London","correspondingAuthor":false,"prefix":"","firstName":"Justin","middleName":"","lastName":"Cobb","suffix":""}],"badges":[],"createdAt":"2025-07-30 09:38:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7251168/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7251168/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s13018-025-06457-w","type":"published","date":"2025-12-02T15:58:14+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":89982923,"identity":"d03c4c9c-15c1-4666-8158-661616427b7f","added_by":"auto","created_at":"2025-08-27 06:30:37","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":35067,"visible":true,"origin":"","legend":"\u003cp\u003eHistogram comparing 1-year postoperative Oxford Hip Scores between patients treated via anterior and posterior hip resurfacing approaches.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eScores are plotted side-by-side. Both groups demonstrated excellent outcomes with a strong ceiling effect. Kernel density estimates (KDE) are overlaid to illustrate the distribution and skew of the data.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7251168/v1/d7f4c124853182cc99cf4b21.png"},{"id":89982925,"identity":"f42b4074-3d02-4c39-85fa-c33aa826d563","added_by":"auto","created_at":"2025-08-27 06:30:37","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":40401,"visible":true,"origin":"","legend":"\u003cp\u003eHistogram comparing postoperative MET scores between anterior and posterior hip resurfacing approaches\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eBoth anterior and posterior groups demonstrated comparable distributions with a near-normal pattern, suggesting similar levels of postoperative physical activity across groups. Kernel density estimates (KDE) are overlaid to illustrate the symmetry and spread of the data.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7251168/v1/b421a3c112df200bc0c0cd2e.png"},{"id":89984732,"identity":"c2f20d2b-5484-4e26-a25b-3ef6388e9b46","added_by":"auto","created_at":"2025-08-27 06:38:38","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":55180,"visible":true,"origin":"","legend":"\u003cp\u003eDot plot showing EQ-5D scores for patients undergoing hip resurfacing via anterior (n = 14) and posterior (n = 17) approaches at 1 year postoperatively.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAll patients in the anterior group (orange) reported the maximum score (1.000), while two patients in the posterior group (blue) reported lower scores, demonstrating a ceiling effect in the dataset.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7251168/v1/d5f5ed2769b707b023c46b31.png"},{"id":89982939,"identity":"e9894278-fa4b-4be7-87b3-0103f187c946","added_by":"auto","created_at":"2025-08-27 06:30:39","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":128470,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of vertical ground reaction force during gait following hip resurfacing via anterior and posterior approaches\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eVertical ground reaction force (vGRF) normalised to body weight across the stance phase of gait in DAA, posterior (POS), and control (CON) groups. All groups exhibit the characteristic biphasic pattern of walking, with no statistically significant differences observed between surgical approaches, as indicated by the Statistical Parametric Mapping (SPM{t) analysis (bottom panel). Shaded areas represent ±1 standard deviation.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7251168/v1/6ab03d889eeddec6af9d7cf3.png"},{"id":89982930,"identity":"016e081b-c174-4f7c-bfab-ee491e54a43c","added_by":"auto","created_at":"2025-08-27 06:30:38","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":71476,"visible":true,"origin":"","legend":"\u003cp\u003eHip joint range of motion in the coronal plane for the affected leg during gait at 6 km/h, comparing the posterior and direct anterior approaches to healthy controls.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eShaded areas represent ±1 standard deviation. The lower panel displays the SPM{t} statistic comparing POS and DAA across the gait cycle.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7251168/v1/6b4e60628e7650411f0dd5e1.jpeg"},{"id":89982934,"identity":"635ff474-debc-4c15-8b32-9e8349a70f8e","added_by":"auto","created_at":"2025-08-27 06:30:38","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":167261,"visible":true,"origin":"","legend":"\u003cp\u003eHip flexion–extension angle across the gait cycle following hip resurfacing via anterior and posterior approaches\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eShaded areas represent ±1 standard deviation. Statistical Parametric Mapping (SPM{t) analysis is shown in the lower panel.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7251168/v1/53dc29f97ac396d98253867b.png"},{"id":97723950,"identity":"4e6bee09-3573-405f-9efe-5527f07ad317","added_by":"auto","created_at":"2025-12-08 16:10:07","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":931920,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7251168/v1/b853a1bb-b833-4658-b0e3-de41c0d87ef3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparison of Anterior and Posterior Approaches for Hip Resurfacing Arthroplasty: A Gait Analysis Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe functional demands on hip arthroplasty patients continue to rise. This trend reflects the procedure’s success and implant longevity, making it a viable option for individuals in their 40s and 50s [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Consequently, younger high-demand patients often opt for hip resurfacing due to its reported superiority in functional outcomes. [\u003cspan additionalcitationids=\"CR3\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e–\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Currently available Metal-on-Metal (MoM) designs retain some controversy due to adverse reactions to metal wear debris. However, excellent results exist when performed well and using proven designs, such as the Birmingham Hip Resurfacing (BHR) [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. More recently, promising early results [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] with ceramic-on-ceramic (CoC) bearings suggest a likely resurgence of interest in hip resurfacing. As hip resurfacing gains popularity, the surgical approach for this technically demanding procedure will face increasing scrutiny. Crucially, its impact on recovery and functional outcomes must be carefully evaluated.\u003c/p\u003e\u003cp\u003eTreadmill gait analysis provides an objective measure of functional performance, enabling quantitative assessment of walking at both normal and high speeds. This more sophisticated measure of function demonstrates symmetrical gait in healthy individuals, while osteoarthritic patients exhibit notable asymmetries. Total hip arthroplasty (THA) improves gait symmetry, however only HRA has been shown to restore physiological gait at higher walking speeds [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Both CoC HRA and the MoM BHR have been shown to restore gait parameters nearly indistinguishable from healthy controls [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Despite an often more extensive exposure it is unclear why HRA patients walk more normally than those undergoing THA.\u003c/p\u003e\u003cp\u003eNormal walking is considered a prerequisite for more demanding activities, such as running, jumping, and sport [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Historically, the success of hip arthroplasty has been assessed predominantly using patient-reported outcome measures (PROMs), which are limited by ceiling effects in high-functioning patients. More recently, the metabolic equivalent of task (MET) score has been proposed as an alternative, offering a patient-centred, normally distributed measure of postoperative physical activity intensity that better captures higher-level functional recovery. The MET reflects engagement in moderate-to-vigorous physical activity, aligning with the expectations and health goals of younger, active patients. The anterior approach is often preferred by patients seeking high functional recovery, and when combined with hip resurfacing arthroplasty, may offer additive benefits for this cohort.\u003c/p\u003e\u003cp\u003eThere are limited published studies describing HRA performed through an anterior approach [\u003cspan additionalcitationids=\"CR13 CR14 CR15 CR16\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e–\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The posterior approach (POS) remains popular due to its familiarity among surgeons and the excellent exposure it provides of both the acetabulum and femur. Modifications to this technique have enhanced femoral head access while preserving the ascending branch of the medial femoral circumflex artery [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. By retaining the anastomoses around the greater trochanter and the retinacular vessels around the femoral neck the risk of avascular necrosis (AVN) can be reduced. AVN has been shown to be a cause for early femoral neck fractures, alongside notching, incomplete seating and varus alignment of the femoral component [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Despite these modifications the posterior approach sacrifices the short external rotators and may carry a higher dislocation rate than others [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In contrast, the direct anterior approach (DAA) is muscle-sparing and has been associated with more physiological gait patterns, potentially offering functional advantages. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTo date, DAA has been associated with improved gait outcomes after THA during the early postoperative period (6–12 weeks) and at one year following surgery, compared to the posterior approach [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. However, a meta-analysis comparing DAA to the lateral (LAT) approach found no clinically meaningful differences in gait beyond three months [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The considerable heterogeneity in gait analysis methods across studies complicates meaningful comparison and data synthesis. Notably, no studies have specifically investigated gait outcomes following HRA using the anterior approach.\u003c/p\u003e\u003cp\u003e\u003cem\u003eObjectives\u003c/em\u003e\u003c/p\u003e\u003cp\u003eThe primary aim was to evaluate the impact of surgical approach on gait biomechanics in high-functioning patients one year after hip resurfacing arthroplasty, compared with a healthy control group. The secondary aim was to examine differences in metabolic equivalent of task (MET) scores across the two groups.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cem\u003eStudy population\u003c/em\u003e\u003c/p\u003e\u003cp\u003eThirty-four male patients who had received a unilateral MoM hip resurfacing (Birmingham Hip Resurfacing, Smith \u0026amp; Nephew) were selected for this study from a longitudinal study of gait (ethics reference number 14/NS/1045). Patients had either a direct anterior (DAA, n = 17) or a posterior (POS, n = 17) approach to surgery by the same surgeon. Exclusion criteria included a BMI greater than 40, over 70 years old or having severe comorbidities. All patients required unilateral HRA, they had no osteoarthritis (OA) or other surgery of their contralateral limb and were able to complete a gait analysis assessment 12 months post-operatively. Eighteen healthy control volunteers (CON) were matched for age, sex, and BMI, if they had no evidence of hip or knee osteoarthritis, no history of hip or knee surgery or injury, or any other lower limb dysfunction (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv class=\"gridtable\"\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\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\u003ePatient Demographics by Surgical Approach and Control Group\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePOS (n = 17)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDAA (n = 17)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCON (n = 17)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (Years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e51 (47–61)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e55 (47–60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e42 (40–62)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBMI (kg/m²)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e25 (2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e26 (2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e26 (4)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTime Postop (Years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.1 (1.0-1.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.2 (1.1–1.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eData are presented as median (interquartile range, IQR) for age and time from surgery to assessment, and mean (standard deviation, SD) for body mass index (BMI). POS = posterior approach; DAA = direct anterior approach; CON = control group.\u003c/em\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003ePatient Reported Outcome Measures (PROMs)\u003c/em\u003e\u003c/p\u003e\u003cp\u003eThe Oxford Hip Score (OHS), EQ5D, and Metabolic Equivalent of Task Score (MET) were completed post-operatively. The MET score was calculated using the same methodology to Edwards et al. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cem\u003eGait Protocol\u003c/em\u003e\u003c/p\u003e\u003cp\u003eAll patients underwent treadmill gait analysis post-operatively (0.9–1.3 years) using an instrumented treadmill [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] (HP/COSMOS, Hab International). The vertical components of ground reaction forces (GRF) were collected on tandem force plates (1000Hz). After 5 minutes of familiarisation walking at 3km/hr, the speed of the treadmill was increased to 4 km/hr then further increased by 0.5 km/hr every 60 seconds until the patient reached their self-determined top walking speed (TWS). Patients wore their own comfortable footwear and were secured in a safety harness throughout the analysis and were able to stop at any point. A 3D motion-capture system (200Hz, VICON Nexus, Oxford Metrics Ltd, Oxford, UK) with 34 anatomically placed body markers on the lower extremities and pelvis was used to record kinematic data[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cem\u003eData analyses\u003c/em\u003e\u003c/p\u003e\u003cp\u003eData was collected during a 30 second period at each walking speed, and the average of 10 steps for each limb was used for further analysis. GRF was normalised to body weight and were time normalised to 100% of the stance phase of the gait cycle. For kinematic data, the 3D marker trajectories were collected at 100 Hz with a 10-camera 3D motion capture system and was time normalised to 100% of the gait cycle and processed in VICON nexus. All data was analysed using custom Matlab scripts (Version 2022a, The Mathworks Inc., United States).\u003c/p\u003e\u003cp\u003e\u003cem\u003eSpatiotemporal gait variables\u003c/em\u003e\u003c/p\u003e\u003cp\u003eTop walking speed (TWS), cadence, step length of the operated limb, and step width were recorded. TWS was determined as the fastest walking speed achieved before breaking out into a run or being limited by discomfort.\u003c/p\u003e\u003cp\u003e\u003cem\u003eGround Reaction Force Profile\u003c/em\u003e\u003c/p\u003e\u003cp\u003eVertical GRFs profiles were collected during the stance phase of the gait cycle and reported at 6 km/hr as this was the highest common walking speed.\u003c/p\u003e\u003cp\u003e\u003cem\u003eKinematic data\u003c/em\u003e\u003c/p\u003e\u003cp\u003eHip angle in the sagittal and coronal plane was collected over the gait cycle. The angle values were ‘zeroed’ to 30 for sagittal, and 0 for coronal, to allow for a better comparison in range of motion, and do not therefore depict absolute hip angle [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eAll data were assessed for normality using the Shapiro–Wilk test. Parametric tests were applied to normally distributed datasets, while non-parametric tests were used for non-normally distributed data. Between-group comparisons for the Oxford Hip Score (OHS) and EQ-5D were conducted using the Mann–Whitney U test, while the MET score was compared using an independent samples t-test.\u003c/p\u003e\u003cp\u003eFor spatiotemporal gait parameters, ground reaction forces (GRF), and joint kinematics, either one-way analysis of variance (ANOVA) or the Kruskal–Wallis test was used, depending on the distribution of each dataset. For time-continuous data such as GRF and hip joint angles over the stance phase, statistical parametric mapping (SPM) was employed. SPM conducts t-tests across the entire normalised time series (0–100% of stance), identifying regions where the test statistic exceeds the critical threshold corresponding to p \u0026lt; 0.05. These regions were considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cem\u003ePatient Demographics\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003ePatient demographics are presented in Table\u0026nbsp;1. The median age (IQR) was 51 (47\u0026ndash;61) years in the POS group, 55 (47\u0026ndash;60) years in the DAA group, and 42 (40\u0026ndash;62) years in the Control group. A Kruskal\u0026ndash;Wallis test showed no statistically significant difference in age between the groups (p = 0.517). Body mass index (BMI) was also comparable across groups, with mean values of 25 (POS), 26 (DAA), and 26 (controls), showing no significant difference using one-way ANOVA (p = 0.517). Similarly, the time from surgery to assessment did not differ significantly between the surgical groups, with a median of 1.1 years for POS and 1.2 years for DAA (Mann\u0026ndash;Whitney U test, p = 0.061). No patients had undergone revision surgery or reoperation at the time of writing.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003ePatient Reported Outcome Measures\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe postoperative scores are demonstrated in figures 1,2 and 3. No significant differences were observed between the postoperative scores for POS and DAA groups respectively for the Oxford Hip Score (OHS: 48 vs. 48, p = 0.651), EQ-5D (1 vs. 1, p = 0.786), or MET score (13.1 vs. 12.6, p = 0.856).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eSpatiotemporal Gait Parameters\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003ePatient walking characteristics are presented in table 2. A one-way ANOVA revealed no significant differences between the groups for normalized top walking speed (F(2,48) = 1.83, p = 0.833), step length (F(2,48) = 4.23, p = 0.523), cadence (F(2,48) = 1.83, p = 0.411), or step width (F(2,48) = 2.98, p = 0.375). A Kruskal\u0026ndash;Wallis test showed no significant differences in top walking speed (TWS; \u0026chi;\u0026sup2;(2) = 10.084, p = 0.08).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e. Walking Characteristics by Surgical Approach and Control Group\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003ePOS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003eDAA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCON\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 154px;\"\u003e\n \u003cp\u003eTWS (km/hr)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e7.5 (6-8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e7 (6.5-8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e7.5 (6-7.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 154px;\"\u003e\n \u003cp\u003eTWSnorm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.66 (0.04)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e0.65 (0.05)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e0.64 (0.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 154px;\"\u003e\n \u003cp\u003eStep Length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e94 (3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e94 (2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e95 (2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 154px;\"\u003e\n \u003cp\u003eCadence\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e104 (3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e103 (2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e104 (2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 154px;\"\u003e\n \u003cp\u003eStep Width\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e8 (2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003e9 (2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e10 (1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cem\u003eData are presented as median (interquartile range, IQR) for top walking speed (TWS), and mean (standard deviation, SD) for all other spatiotemporal variables. TWSnorm = normalised top walking speed; POS = posterior approach; DAA = direct anterior approach; CON = control group.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eGround Reaction Force Profile\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eSPM analysis detected no significant differences (p=\u0026lt;0.05) in ground reaction force (GRF) across the stance phase between the POS and DAA groups when compared at 6 km/hr against healthy controls, figure 4.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eHip Range of Motion\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAnalysis of hip joint kinematics revealed no statistically significant differences in range of motion between POS and DAA approaches across the gait cycle in either the coronal or sagittal planes. In the coronal plane (figure 5), both groups exhibited similar patterns of adduction and abduction, with a peak difference of approximately 2 degrees and the SPM{t} statistic remaining below the critical threshold (t* = 3.613, \u0026alpha; = 0.05) throughout the gait cycle. In the sagittal plane (figure 6), while slight variations were observed\u0026mdash;particularly with the DAA group showing marginally greater peak extension\u0026mdash;the SPM{t} curve again remained below the critical threshold (t* = 3.202, \u0026alpha; = 0.05), indicating no statistically significant difference. Both resurfacing groups demonstrated similar motion profiles overall.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe primary finding is that at 1 year postop, patients undergoing HRA demonstrate gait which is comparable to age-matched healthy controls, regardless of surgical approach. Secondary finding is that HRA delivers excellent PROMs \u0026mdash; maximal OHS, and a MET score averaging 13, which equates to the ability to perform high-intensity activities such as running, vigorous cycling, or competitive sports, reflecting exceptional functional capacity postoperatively.\u003c/p\u003e\u003cp\u003eOur findings align with previous studies analysing spatiotemporal variables, demonstrating that HRA can restore near-physiological gait [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Furthermore, this study is the first to assess multiplanar hip angle kinematics using SPM throughout the gait cycle, showing restoration to near-normal levels following resurfacing with either approach. A comparable study [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] investigated the three most commonly utilised surgical approaches to the hip\u0026mdash; DAA, POS, and LAT\u0026mdash;in the context of total hip arthroplasty. Ryan et al. found that the DAA and lateral approaches resulted in more favourable sagittal and frontal plane gait kinematics compared to the posterior approach. Only the DAA group demonstrated spatiotemporal parameters within the normal range. Notably, their DAA cohort exhibited evidence of hip abductor unloading during the loading response phase\u0026mdash;a pattern not observed in our study. These findings suggest that the choice of arthroplasty type (HRA vs THA) may have a greater influence on postoperative gait biomechanics than surgical approach alone.\u003c/p\u003e\u003cp\u003eThe mechanisms underlying the ability of hip resurfacing to restore more normal gait remain unclear. To date, one Randomised Controlled Trail (RCT) [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] has described its superiority over THA, particularly at higher walking speeds. However, this was not replicated in other trials [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], with Lavigne et al. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] concluding that large-head THA provides the same benefit to restoring gait as HRA. Their trial may have been inadequately powered [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], however, it points to head size as a potential determinant. In a biomechanical study [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] conducted in our lab restoring native head size when combined with capsular repair restored tension to the ligaments which were able to wrap around the head. Conversely, THA with a 32mm head left the capsule slack thus defunctioning the capsule. Interestingly, an article comparing gait parameters across different head sizes found that a larger head size (36 mm) improved gait patterns [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] at a mean of 3.5 years postoperatively. Longer-term functional benefits of larger head sizes (36-44mm) have also been described using the UCLA score at five years [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. At higher activity levels such as fast walking or running, peak hip stresses can reach seven times body weight [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The resulting load transfer to the proximal femur is greatly impacted by head size, but equally the choice of materials and the presence of metalwork extending into the medullary canal. HRA has been shown to preserve native proximal femoral elasticity [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] however, these findings are based on studies of now-withdrawn implants. The influence of fixation method, femoral stem size, and materials on proximal femoral elasticity, particularly with emerging CoC HRA, remains understudied.\u003c/p\u003e\u003cp\u003eA limitation of our study is that it offers only a snapshot of data at one year postoperatively. DAA has been shown to offer a faster postoperative functional recovery, and a resulting shorter hospital stay compared to POS [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. It is therefore possible that a faster recovery trajectory in the DAA cohort was not captured. Similarly, the lack of pre-operative data limits baseline comparisons and precludes assessment of preoperative impairment severity on postoperative outcomes. We are however reassured by the fact our patients reached the levels of healthy controls despite suffering with debilitating osteoarthritis preoperatively. Furthermore, only male patients were included, as female sex is considered a contraindication for MoM HRA. While the lack of randomisation introduces a risk of selection bias, robust demographic matching across the three groups was employed. Strengths of our study include prospective data collection, complete postoperative hip scores, along with a personalised assessment of physical activity (PA) based on the MET score [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eObjective functional measures, such as gait analysis, are crucial in evaluating arthroplasty outcomes, as limited walking speed often indicates reduced capacity for high-demand physical activities [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Additionally, a more normal gait reduces fall risk in older patients [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. As physical function improves, patients may be better able to engage in moderate-to-vigorous physical activity (MVPA), which is strongly associated with reduced cardiometabolic disease risk and lower all-cause mortality [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. In line with this, current WHO guidelines recommend that adults maintain 150\u0026ndash;300 minutes of moderate-intensity aerobic or at least 75\u0026ndash;150 minutes of vigorous-intensity [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. This equates to between 450\u0026ndash;900 Metabolic Equivalent of Task (MET) minutes. In our study, postoperative MET scores for POS (13.1) and DAA (12.6) showed no significant difference between approaches but indicated engagement in MVPA, reflecting high functional recovery. Crucially, the MET score mitigated the ceiling effect of the OHS by capturing higher levels of physical activity that were previously undetectable, as demonstrated in Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eThe direct anterior approach appeals to both surgeons and patients by minimising muscular damage and facilitating rapid recovery, making it particularly attractive for high-demand patients, often the same cohort as resurfacing candidates. However, while early discharge may offer economic benefits, these may be offset by the higher cost of DAA compared to the posterior approach [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Despite excellent outcomes in specialist centres [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], an additional learning curve exists even for experienced DAA surgeons when adapting the approach for resurfacing. Balancing adequate exposure, femoral mobility, and capsular blood supply preservation is achievable but influenced by patient factors [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. When performed safely, DAA complements hip resurfacing in high-demand patients, supporting the restoration of function to levels enabling high-intensity health enhancing PA. Future studies should incorporate randomisation, preoperative gait analysis, and postoperative activity tracking via accelerometers at multiple time points to determine whether one approach offers superior outcomes.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study is the first to demonstrate equivalent gait outcomes between the anterior and posterior approaches for HRA, with both restoring normal patterns. While no differences were observed between DAA and POS, both approaches yielded successful outcomes in this high-functioning cohort.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eAHI \u0026nbsp;Acromiohumeral interval\u003c/p\u003e\n\u003cp\u003eASES \u0026nbsp;American Shoulder and Elbow Surgeons\u003c/p\u003e\n\u003cp\u003eAUC \u0026nbsp;Area under the curve\u003c/p\u003e\n\u003cp\u003eCHL \u0026nbsp;Coracohumeral ligament\u003c/p\u003e\n\u003cp\u003eISP \u0026nbsp;Infraspinatus\u003c/p\u003e\n\u003cp\u003eLHB \u0026nbsp;Long head of the biceps\u003c/p\u003e\n\u003cp\u003eMCID \u0026nbsp;Minimal clinically important difference\u003c/p\u003e\n\u003cp\u003eMRI \u0026nbsp;Magnetic resonance imaging\u003c/p\u003e\n\u003cp\u003eRCTs \u0026nbsp;Rotator cuff tears\u003c/p\u003e\n\u003cp\u003eRI \u0026nbsp;Rotator interval\u003c/p\u003e\n\u003cp\u003eROC \u0026nbsp;Receiver operating characteristic\u003c/p\u003e\n\u003cp\u003eROM \u0026nbsp;Range of motion\u003c/p\u003e\n\u003cp\u003eSGHL \u0026nbsp;Superior glenohumeral ligament\u003c/p\u003e\n\u003cp\u003eSSC \u0026nbsp;Subscapularis\u003c/p\u003e\n\u003cp\u003eSSP \u0026nbsp;Supraspinatus\u003c/p\u003e\n\u003cp\u003eVAS \u0026nbsp;Visual analog scale\u003c/p\u003e\n\u003cp\u003eHRA \u0026nbsp;Hip resurfacing arthroplasty\u003c/p\u003e\n\u003cp\u003ePOS \u0026nbsp;Posterior approach\u003c/p\u003e\n\u003cp\u003eDAA \u0026nbsp;Direct anterior approach\u003c/p\u003e\n\u003cp\u003eOHS \u0026nbsp;Oxford Hip Score\u003c/p\u003e\n\u003cp\u003eMET \u0026nbsp;Metabolic Equivalent of Task\u003c/p\u003e\n\u003cp\u003eEQ-5D \u0026nbsp;EuroQol-5 Dimensions\u003c/p\u003e\n\u003cp\u003ePROMs \u0026nbsp;Patient-reported outcome measures\u003c/p\u003e\n\u003cp\u003eMoM \u0026nbsp;Metal-on-metal\u003c/p\u003e\n\u003cp\u003eBHR \u0026nbsp;Birmingham Hip Resurfacing\u003c/p\u003e\n\u003cp\u003eCoC \u0026nbsp;Ceramic-on-ceramic\u003c/p\u003e\n\u003cp\u003eTHA \u0026nbsp;Total hip arthroplasty\u003c/p\u003e\n\u003cp\u003eLAT \u0026nbsp;Lateral approach\u003c/p\u003e\n\u003cp\u003eOA \u0026nbsp;Osteoarthritis\u003c/p\u003e\n\u003cp\u003eBMI \u0026nbsp;Body mass index\u003c/p\u003e\n\u003cp\u003eCON \u0026nbsp;Control group\u003c/p\u003e\n\u003cp\u003eGRF \u0026nbsp;Ground reaction force\u003c/p\u003e\n\u003cp\u003eTWS \u0026nbsp;Top walking speed\u003c/p\u003e\n\u003cp\u003eTWSnorm \u0026nbsp;Normalised top walking speed\u003c/p\u003e\n\u003cp\u003eSPM \u0026nbsp;Statistical parametric mapping\u003c/p\u003e\n\u003cp\u003eKDE \u0026nbsp;Kernel density estimate\u003c/p\u003e\n\u003cp\u003eRCT \u0026nbsp;Randomised controlled trial\u003c/p\u003e\n\u003cp\u003ePA \u0026nbsp;Physical activity\u003c/p\u003e\n\u003cp\u003eMVPA \u0026nbsp;Moderate-to-vigorous physical activity\u003c/p\u003e\n\u003cp\u003eWHO \u0026nbsp;World Health Organization\u003c/p\u003e\n\u003cp\u003eUK \u0026nbsp;United Kingdom\u003c/p\u003e\n\u003cp\u003eSD \u0026nbsp;Standard deviation\u003c/p\u003e\n\u003cp\u003eIQR \u0026nbsp;Interquartile range\u003c/p\u003e\n\u003cp\u003eANOVA \u0026nbsp;Analysis of variance\u003c/p\u003e\n\u003cp\u003eMATLAB \u0026nbsp;Matrix Laboratory (software used for data analysis)\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e: All authors have read and agreed to the published version of the manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e: The datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e: The authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e: No funding was received to support the conduct of this study or the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u0026nbsp;\u003c/strong\u003eWe acknowledge the contribution of Rima Nasser in helping identify the patients who had undergone surgery to be included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics statement\u003c/strong\u003e: This study was approved by our local ethics committee (ethics reference number 14/NS/1045).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eEkhtiari S, Sefton AK, Wood TJ, Petruccelli DT, Winemaker MJ, de Beer JD. The Changing Characteristics of Arthroplasty Patients: A Retrospective Cohort Study. J Arthroplasty. 2021;36(7):2418-23.\u003c/li\u003e\n\u003cli\u003eMorse KW, Premkumar A, Zhu A, Morgenstern R, Su EP. Return to Sport After Hip Resurfacing Arthroplasty. Orthop J Sports Med. 2021;9(5):23259671211003521.\u003c/li\u003e\n\u003cli\u003eOxblom A, Hedlund H, Nemes S, Brismar H, Fellander-Tsai L, Rolfson O. Patient-reported outcomes in hip resurfacing versus conventional total hip arthroplasty: a register-based matched cohort study of 726 patients. Acta Orthop. 2019;90(4):318-23.\u003c/li\u003e\n\u003cli\u003eGirard J, Lons A, Pommepuy T, Isida R, Benad K, Putman S. High-impact sport after hip resurfacing: The Ironman triathlon. Orthop Traumatol Surg Res. 2017;103(5):675-8.\u003c/li\u003e\n\u003cli\u003eDhawan R, Young DA, Van Eemeren A, Shimmin A. Birmingham Hip Resurfacing at 20 years. Bone Joint J. 2023;105-B(9):946-52.\u003c/li\u003e\n\u003cli\u003eLin D, Xu J, Weinrauch P, Young DA, De Smet K, Manktelow A, et al. Two-Year Results of Ceramic-on-Ceramic Hip Resurfacing in an International Multicenter Cohort. J Arthroplasty. 2024;39(11):2800-6.\u003c/li\u003e\n\u003cli\u003eGerhardt D, Mors TGT, Hannink G, Van Susante JLC. Resurfacing hip arthroplasty better preserves a normal gait pattern at increasing walking speeds compared to total hip arthroplasty. Acta Orthop. 2019;90(3):231-6.\u003c/li\u003e\n\u003cli\u003eWiik AV, Lambkin R, Cobb JP. Gait after Birmingham Hip Resurfacing: an age-matched controlled prospective study. Bone Joint J. 2019;101-B(11):1423-30.\u003c/li\u003e\n\u003cli\u003eMaslivec A, Halewood C, Clarke S, Cobb J. Hip resurfacing arthroplasty in women: A novel ceramic device enables near normal gait function. Gait Posture. 2023;103:166-71.\u003c/li\u003e\n\u003cli\u003eCiprandi D, Bertozzi F, Zago M, Ferreira CLP, Boari G, Sforza C, et al. Study of the association between gait variability and physical activity. Eur Rev Aging Phys Act. 2017;14:19.\u003c/li\u003e\n\u003cli\u003eBaker R. Gait analysis methods in rehabilitation. J Neuroeng Rehabil. 2006;3:4.\u003c/li\u003e\n\u003cli\u003eSuraci AB, Bhullar RS, Dobransky JS, Beaule PE. Hueter Anterior Approach for Metal-on-Metal Hip Resurfacing Arthroplasty: 555 Cases at a Minimum Five-Year Follow-Up. J Arthroplasty. 2021;36(9):3200-8.\u003c/li\u003e\n\u003cli\u003eLall AC, Annin S, Diulus SC, Maldonado DR, Ankem HK, Domb BG. Direct anterior Birmingham hip resurfacing: surgical technique. Techniques in Orthopaedics. 2021;36(4):536-40.\u003c/li\u003e\n\u003cli\u003eKreuzer S, Leffers K, Kumar S. Direct anterior approach for hip resurfacing: surgical technique and complications. Clinical Orthopaedics and Related Research\u0026reg;. 2011;469:1574-81.\u003c/li\u003e\n\u003cli\u003eKeggi JM, Kennon RE, Rubin LE, Keggi KJ. The direct anterior surgical approach for hip resurfacing arthroplasty without a traction table. Techniques in Orthopaedics. 2010;25(1):12-7.\u003c/li\u003e\n\u003cli\u003eGoltzer O, Guild III GN. Hip resurfacing utilizing the direct anterior approach. Techniques in Orthopaedics. 2021;36(1):35-9.\u003c/li\u003e\n\u003cli\u003eBenoit B, Gofton W, Beaul\u0026eacute; PE. Hueter anterior approach for hip resurfacing: assessment of the learning curve. Orthopedic Clinics of North America. 2009;40(3):357-63.\u003c/li\u003e\n\u003cli\u003eSteffen RT, De Smet KA, Murray DW, Gill HS. A modified posterior approach preserves femoral head oxgenation during hip resurfacing. J Arthroplasty. 2011;26(3):404-8.\u003c/li\u003e\n\u003cli\u003eSteffen RT, Athanasou NA, Gill HS, Murray DW. Avascular necrosis associated with fracture of the femoral neck after hip resurfacing: histological assessment of femoral bone from retrieval specimens. J Bone Joint Surg Br. 2010;92(6):787-93.\u003c/li\u003e\n\u003cli\u003eKoster M, Luzier AD, Temmerman OP, Vos SJ, Benner JL. How do dislocation rates differ between different approaches to total hip arthroplasty? A systematic review and meta-analysis. Journal of Orthopaedics, Trauma and Rehabilitation. 2023;30(1):22104917221147688.\u003c/li\u003e\n\u003cli\u003eRyan NS, Kowalski E, Beaule PE, Lamontagne M. The Effect of Surgical Approach and Hip Offset Reconstruction on Gait Biomechanics Following Total Hip Arthroplasty. J Arthroplasty. 2023.\u003c/li\u003e\n\u003cli\u003eMayr E, Nogler M, Benedetti MG, Kessler O, Reinthaler A, Krismer M, et al. A prospective randomized assessment of earlier functional recovery in THA patients treated by minimally invasive direct anterior approach: a gait analysis study. Clin Biomech (Bristol, Avon). 2009;24(10):812-8.\u003c/li\u003e\n\u003cli\u003eRyan NS, Kowalski E, Beaule PE, Lamontagne M. The Effect of Surgical Approach and Hip Offset Reconstruction on Gait Biomechanics Following Total Hip Arthroplasty. J Arthroplasty. 2024;39(2):402-8 e1.\u003c/li\u003e\n\u003cli\u003eYoo JI, Cha YH, Kim KJ, Kim HY, Choy WS, Hwang SC. Gait analysis after total hip arthroplasty using direct anterior approach versus anterolateral approach: a systematic review and meta-analysis. BMC Musculoskelet Disord. 2019;20(1):63.\u003c/li\u003e\n\u003cli\u003eEdwards TC, Guest B, Garner A, Logishetty K, Liddle AD, Cobb JP. The metabolic equivalent of task score : a useful metric for comparing high-functioning hip arthroplasty patients. Bone Joint Res. 2022;11(5):317-26.\u003c/li\u003e\n\u003cli\u003eSystems VM. Plug-in Gait Product Guide \u0026ndash; Foundation Notes. Oxford, UK: Oxford Metrics Ltd.; 2010.\u003c/li\u003e\n\u003cli\u003ePetersen MK, Andersen NT, Mogensen P, Voight M, S\u0026oslash;balle K. Gait analysis after total hip replacement with hip resurfacing implant or Mallory-head Exeter prosthesis: a randomised controlled trial. International orthopaedics. 2011;35:667-74.\u003c/li\u003e\n\u003cli\u003eLavigne M, Therrien M, Nantel J, Roy A, Prince F, Vendittoli P-A. The John Charnley Award: The functional outcome of hip resurfacing and large-head THA is the same: a randomized, double-blind study. Clinical Orthopaedics and Related Research\u0026reg;. 2010;468:326-36.\u003c/li\u003e\n\u003cli\u003eCobb J. Letter to the editor: The functional outcome of hip resurfacing and large-head THA is the same: a randomized, double-blind study. Clin Orthop Relat Res. 2010;468(11):3134.\u003c/li\u003e\n\u003cli\u003eLogishetty K, van Arkel RJ, Ng KCG, Muirhead-Allwood SK, Cobb JP, Jeffers JRT. Hip capsule biomechanics after arthroplasty: the effect of implant, approach, and surgical repair. Bone Joint J. 2019;101-B(4):426-34.\u003c/li\u003e\n\u003cli\u003eStolarczyk A, Stolarczyk M, Oleksy L, Maciag GJ, Stepinski P, Szymczak J, et al. Analysis of biomechanical gait parameters in patients after total hip replacement operated via anterolateral approach depending on size of the femoral head implant: retrospective matched-cohort study. Arch Orthop Trauma Surg. 2022;142(12):4015-23.\u003c/li\u003e\n\u003cli\u003eTsikandylakis G, Mortensen KRL, Gromov K, Mohaddes M, Malchau H, Troelsen A. The Use of Large Metal Heads in Thin Vitamin E-Doped Cross-Linked Polyethylene Inserts Does Not Increase Polyethylene Wear in Total Hip Arthroplasty: 5-Year Results From a Randomized Controlled Trial. J Arthroplasty. 2024;39(7):1804-10.\u003c/li\u003e\n\u003cli\u003eBergmann G, Graichen F, Rohlmann A. Hip joint loading during walking and running, measured in two patients. J Biomech. 1993;26(8):969-90.\u003c/li\u003e\n\u003cli\u003eDeuel CR, Jamali AA, Stover SM, Hazelwood SJ. Alterations in femoral strain following hip resurfacing and total hip replacement. J Bone Joint Surg Br. 2009;91(1):124-30.\u003c/li\u003e\n\u003cli\u003eWik T, \u0026Oslash;stbyhaug P, Klaksvik J, Aamodt A. Increased strain in the femoral neck following insertion of a resurfacing femoral prosthesis. The Journal of Bone \u0026amp; Joint Surgery British Volume. 2010;92(3):461-7.\u003c/li\u003e\n\u003cli\u003eAng JJM, Onggo JR, Stokes CM, Ambikaipalan A. Comparing direct anterior approach versus posterior approach or lateral approach in total hip arthroplasty: a systematic review and meta-analysis. Eur J Orthop Surg Traumatol. 2023;33(7):2773-92.\u003c/li\u003e\n\u003cli\u003eNascimento MM, Gouveia ER, Gouveia BR, Marques A, Martins F, Przednowek K, et al. Associations of Gait Speed, Cadence, Gait Stability Ratio, and Body Balance with Falls in Older Adults. Int J Environ Res Public Health. 2022;19(21).\u003c/li\u003e\n\u003cli\u003eStrain T, Wijndaele K, Dempsey PC, Sharp SJ, Pearce M, Jeon J, et al. Wearable-device-measured physical activity and future health risk. Nat Med. 2020;26(9):1385-91.\u003c/li\u003e\n\u003cli\u003eLindsay T, Wijndaele K, Westgate K, Dempsey P, Strain T, De Lucia Rolfe E, et al. Joint associations between objectively measured physical activity volume and intensity with body fatness: the Fenland study. Int J Obes (Lond). 2022;46(1):169-77.\u003c/li\u003e\n\u003cli\u003eBull FC, Al-Ansari SS, Biddle S, Borodulin K, Buman MP, Cardon G, et al. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Br J Sports Med. 2020;54(24):1451-62.\u003c/li\u003e\n\u003cli\u003eAwad ME, Farley BJ, Mostafa G, Saleh KJ. Direct anterior approach has short-term functional benefit and higher resource requirements compared with the posterior approach in primary total hip arthroplasty : a meta-analysis of functional outcomes and cost. Bone Joint J. 2021;103-B(6):1078-87.\u003c/li\u003e\n\u003cli\u003eKarunaseelan KJ, Nasser R, Jeffers JRT, Cobb JP. Optimal hip capsular release for joint exposure in hip resurfacing via the direct anterior approach. Bone Joint J. 2024;106-B(3 Supple A):59-66.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Anterior Approach, Posterior Approach, Hip Resurfacing, Hip Arthroplasty, Gait Analysis","lastPublishedDoi":"10.21203/rs.3.rs-7251168/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7251168/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003eHip resurfacing arthroplasty (HRA) is commonly performed using the posterior approach (POS), which is familiar to most surgeons and allows excellent exposure. The short external rotators and often the gluteus maximus are incised with the POS, which may adversely affect gait. The direct anterior approach (DAA), which is muscle sparing has been shown to preserve more physiological gait patterns in total hip arthroplasty.\u003c/p\u003e\n\u003cp\u003eThis study aims to compare outcomes between POS and DAA approaches using gait analysis, the Oxford Hip Score (OHS), Metabolic Equivalent of Task (MET), and EQ-5D.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e Seventeen unilateral DAA and 17 POS HRA males were matched for age and BMI. Patients underwent instrumented treadmill gait analysis and completed patient reported outcome scores (PROMs) at a mean of 1.5 (0.9–1.8) years post-operatively. Kinematics and kinetics were recorded using motion capture and force plate data. Group differences were assessed using statistical parametric mapping. These data were compared to a group of 19 healthy male controls matched for age and BMI.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e Gait analysis postoperatively revealed no significant differences in hip kinematics in either the coronal or sagittal planes between the posterior and direct anterior approaches. Statistical parametric mapping showed no differences in vertical ground reaction forces across the stance phase. Spatiotemporal gait parameters, including top walking speed, cadence, step length, and step width, were comparable between groups and closely aligned with healthy controls. Both cohorts achieved similar postoperative OHS (mean:48, p = 0.651), EQ-5D (median:1.0, p = 0.786), and MET scores (POS:13.1 vs DAA:12.6, p=0.856).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e: This is the first study to analyse gait following HRA via the DAA. Both DAA and POS restored normal gait patterns, with no significant differences in kinematics, kinetics, or spatiotemporal parameters, and results comparable to matched healthy controls. PROMSs were similarly excellent across groups indicating high functional recovery and engagement in moderate-to-vigorous physical activity.\u003c/p\u003e","manuscriptTitle":"Comparison of Anterior and Posterior Approaches for Hip Resurfacing Arthroplasty: A Gait Analysis Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-27 06:30:31","doi":"10.21203/rs.3.rs-7251168/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-09-27T07:35:22+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-14T09:29:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"26383209273269333935974853080986403403","date":"2025-08-20T07:23:45+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-19T08:47:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"154154359637440015344386955666086457646","date":"2025-08-18T08:33:06+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-18T07:16:43+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-31T07:11:07+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-31T05:50:09+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Orthopaedic Surgery and Research","date":"2025-07-30T09:22:55+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"620a31e7-05c9-4d74-8add-2c4d1b297788","owner":[],"postedDate":"August 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-12-08T16:03:38+00:00","versionOfRecord":{"articleIdentity":"rs-7251168","link":"https://doi.org/10.1186/s13018-025-06457-w","journal":{"identity":"journal-of-orthopaedic-surgery-and-research","isVorOnly":false,"title":"Journal of Orthopaedic Surgery and Research"},"publishedOn":"2025-12-02 15:58:14","publishedOnDateReadable":"December 2nd, 2025"},"versionCreatedAt":"2025-08-27 06:30:31","video":"","vorDoi":"10.1186/s13018-025-06457-w","vorDoiUrl":"https://doi.org/10.1186/s13018-025-06457-w","workflowStages":[]},"version":"v1","identity":"rs-7251168","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7251168","identity":"rs-7251168","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}