Optimizing Initial Biomechanical Strength ("Time Zero") of Posterior Repair in Total Hip Arthroplasty: A Biomechanical Comparison of Suture Materials and Knot Configurations

Optimizing Initial Biomechanical Strength ("Time Zero") of Posterior Repair in Total Hip Arthroplasty: A Biomechanical Comparison of Suture Materials and Knot Configurations | 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 Optimizing Initial Biomechanical Strength ("Time Zero") of Posterior Repair in Total Hip Arthroplasty: A Biomechanical Comparison of Suture Materials and Knot Configurations Ming Chen, Xiang Liu, Dayi Chen, Xiaojing Li, Haoyuan Du, Yulong Sun, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9001769/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract Introduction: Posterior soft tissue repair (PCR) is recognized as a critical procedural step for mitigating early dislocation following total hip arthroplasty (THA) performed via the posterolateral approach. However, biological healing of the capsulotendinous structures typically requires 6 to 12 weeks, creating a prolonged window of mechanical vulnerability. Concurrently, the increasing implementation of Enhanced Recovery After Surgery (ERAS) protocols demands immediate postoperative mobilization. Consequently, the initial biomechanical strength—often referred to as "Time Zero" strength—of the repair construct serves as the primary defense against construct failure. This study aims to identify the optimal suture material and knot configuration to maximize initial repair stability and safely facilitate aggressive early rehabilitation. Materials and methods This in vitro biomechanical study was conducted in two sequential phases. Phase 1 evaluated the baseline tensile properties of three prevalent suture materials: #2 Ethibond, #0 Vicryl, and 3 − 0 PGLA. Phase 2 utilized a standardized porcine dermal surrogate to accurately model the human posterior capsule, effectively controlling for the biological heterogeneity of human cadaveric tissue. Eight distinct suture configurations, encompassing both single- and double-strand methods, were rigorously compared. Key biomechanical metrics extracted from uniaxial quasi-static load-to-failure testing included maximum failure load, load at 2mm gap formation, and construct stiffness. Results Phase 1 demonstrated that the non-absorbable #2 Ethibond possessed significantly superior ultimate tensile strength (92.44 ± 8.72 N) and structural stiffness compared to the absorbable alternatives (P < 0.001). In Phase 2, double-strand configurations significantly outperformed all single-strand techniques. Specifically, the double-strand Nice knot achieved a maximum failure load of 104.04 ± 8.68 N, nearly double that of the conventional simple interrupted suture (54.19 ± 8.24 N). Furthermore, the Nice knot exhibited the highest construct stiffness (12.59 ± 1.21 N/mm), providing superior resistance to deleterious tissue gap formation, while requiring significantly less operative time (183 ± 9.89 s) compared to complex arthroscopic sliding knots (P < 0.05). Conclusions Current absorbable sutures and traditional static knots provide insufficient fixation strength to withstand the physiological loads generated by early mobilization. A reconstructive strategy combining #2 Ethibond with a double-strand Nice knot offers optimal "Time Zero" biomechanical strength and high stiffness. This construct effectively restricts tissue gap formation to under the 2mm safety threshold, creating a secure mechanical microenvironment for biological healing and robustly supporting the implementation of immediate postoperative ERAS protocols. Total Hip Arthroplasty Biomechanics Posterior Soft Tissue Repair Suture Techniques Nice Knot Enhanced Recovery After Surgery Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 1. Introduction In the contemporary landscape of orthopedic surgery, total hip arthroplasty (THA) stands as a highly successful intervention for reliably alleviating pain and restoring joint kinematics in patients afflicted with severe hip pathologies [ 1 , 3 ].With continuous advancements in bearing tribology and prosthesis design, THA currently achieves exceptional long-term survivorship [ 4 ].However, driven by a globally aging demographic and a corresponding surge in surgical volume, early postoperative dislocation remains a formidable and devastating complication [ 5 ].Dislocation profoundly impairs the patient's quality of life and imposes a severe socioeconomic burden, as recurrent instability often necessitates complex surgical revisions and prolonged hospital readmissions [ 6 , 7 ].Therefore, establishing robust, evidence-based strategies to mitigate the risk of early dislocation remains an urgent priority in arthroplasty research. The surgical approach is inextricably linked to the intrinsic risk of postoperative instability. The posterolateral approach is globally favored by arthroplasty surgeons due to its excellent anatomical exposure, preservation of the critical hip abductor mechanism, and facilitation of precise component positioning [ 8 ].However, this trajectory inherently demands the transection of the short external rotator muscles and the posterior articular capsule [ 2 , 5 ].The native hip capsule is a highly sophisticated biomechanical restraint system. The posterior soft tissue complex (PSTC) provides the primary tensile restraint when the hip is subjected to the high-risk position of flexion, adduction, and internal rotation [ 37 ].Its iatrogenic absence drastically compromises posterior stability, rendering the femoral head highly susceptible to posterior subluxation [ 9 , 10 ]. Historical literature indicates that if the posterior soft tissues are left unrepaired, the early dislocation rate can soar to an unacceptable 4% to 9% [ 11 – 13 ]. Substantial evidence-based literature confirms that meticulous anatomical reconstruction of the posterior structures through enhanced posterior capsule repair (PCR) significantly bolsters the dislocation resistance torque, restores proprioception, and effectively reduces dislocation rates [ 4 , 10 , 14 ].Nevertheless, clinical follow-ups reveal that a subset of patients still experience early dislocation despite receiving meticulously executed PCR [ 9 ].Advanced imaging and biomechanical investigations indicate that these "failed repairs" rarely result from the native host tissue tearing. Instead, failure typically originates at the "weak link" within the exogenous repair construct—the suture-knot interface [ 15 ].Biomechanical investigations underscore that merely placing sutures does not guarantee clinical success [ 16 ]. The structural repair of the capsule and short external rotators fundamentally relies on a complex biological healing cascade that requires 6 to 12 weeks to mature. During the initial inflammatory phase, the local tissue environment is catabolic, and inherent mechanical holding power drops to its absolute nadir [ 17 ].In the subsequent proliferative phase, fibroblasts secrete weak, uncross-linked Type III collagen [ 18 ].Conversely, modern Enhanced Recovery After Surgery (ERAS) protocols mandate immediate postoperative mobilization, often within hours of surgery [ 34 ].Consequently, the entire physiological load of early rehabilitation is borne exclusively by the synthetic suture material and the spatial geometry of the knot construct. Thus, the initial biomechanical strength—or "Time Zero" strength—achieved on the operating table serves as the final mechanical safeguard against early dislocation. To address the persistent risk of early dislocation and navigate the rigorous biomechanical demands of the soft tissue healing phase under ERAS pathways, the present study utilizes a highly standardized in vitro surrogate model to conduct rigorous biomechanical tensile testing. The specific objectives are to: (1) evaluate and quantify the intrinsic tensile properties of clinically prevalent suture materials; (2) systematically evaluate the ultimate strength, construct stiffness, and failure modes of eight distinct knot configurations; and (3) synthesize these empirical findings to formulate an optimal, evidence-based posterior soft tissue repair algorithm that maximizes "Time Zero" stability. 2. Materials and methods 2.1 Overview of Experimental Design The in vitro biomechanical testing protocol was meticulously designed in two progressive phases to isolate specific mechanical variables. Phase 1 evaluated the baseline tensile properties of different suture materials independently, establishing material-specific mechanical baselines without tissue confounding factors. Phase 2 utilized a highly standardized soft tissue surrogate to evaluate the comprehensive biomechanical efficacy of eight distinct suture-knot configurations in a simulated surgical environment. All tests were conducted in a climate-controlled biomechanics laboratory at 25°C using a microcomputer-controlled universal testing machine (PDDW-2; Jinan Pinde Testing Machine Co., Ltd.). 2.2 Phase 1: Baseline Mechanical Properties of Suture Materials Three clinically prevalent sutures were tested to assess their intrinsic tensile performance and inherent knot security: 1.Ethibond Group (n=7): Size #2 braided polyester non-absorbable suture. 2.Vicryl Group (n=9): Size #0 braided polyglactin 910 absorbable suture. 3.PGLA Group (n=10): Size 3-0 braided polyglycolic acid absorbable suture. All specimens were manually tied into closed loops using a standardized surgical knot configuration featuring three locking throws. This technique was employed to eliminate operator-induced knot slippage as a confounding variable, effectively isolating the intrinsic tensile strength and surface friction coefficient of the materials themselves. 2.3 Phase 2: Biomechanical Comparison of Suture Configurations Obtaining fresh, homogeneous human cadaveric hip capsules is logistically challenging and scientifically problematic; such specimens invariably exhibit severe age-related collagen degeneration, macroscopic structural defects, and vast inter-specimen variability, which severely confounds baseline variables [19].Therefore, porcine dermal skin was utilized as a scientifically validated and highly standardized surrogate model. Porcine dermis is histologically analogous to dense human capsular connective tissue, featuring an interwoven network of Type I and III collagen fibers that accurately replicate the "cheese-wiring" (suture cut-through) resistance of the human hip capsule [35, 36] . Strict standardization protocols were enforced during specimen preparation. Dermis was harvested uniformly from the dorsum of age-matched domestic pigs and precisely sectioned into 100 mm × 30 mm strips. A high-precision digital caliper was utilized to ensure a strict thickness tolerance of 4.0 ± 0.2 mm across all specimens. A central, full-thickness transverse incision was created with a #11 scalpel blade to mechanically simulate a surgical capsulotomy. The simulated capsular edges were approximated for suturing, and physiological tissue hydration was continuously maintained utilizing a 0.9% saline spray to accurately replicate in vivo viscoelasticity and fluid mechanics [28] . Eight distinct knot configurations were evaluated, categorized as follows: 1.Single-Strand Static Controls (Fig. 1): Group A (Simple Interrupted), Group B (Figure-of-8). 2. Double-Strand Sliding Knots (Fig. 2): Group C (Modified Racking Hitch – MRH [26] ), Group D (Nice knot [25] ). 3. Single-Strand Sliding Knots (Fig. 3): Group E (Weston knot), Group F (Static Surgeon's knot), Group G (Duncan loop), Group H (SMC knot [23] ). 2.4 Biomechanical Testing Protocol Phase 2 constructs underwent immediate "Time Zero" tensile testing ( Fig. 4 ) following preparation. Specimens were mounted vertically within the testing machine clamps. A 1.0 N preload was applied for 10 seconds to systematically eliminate viscoelastic slack and uniformize the tissue fibers, defining the strict zero-displacement baseline. Quasistatic uniaxial tension was then applied at a constant displacement rate of 20 mm/min until catastrophic structural failure occurred. Core biomechanical parameters extracted from the continuous load-displacement curves included: ( 1 ) Maximum Failure Load (F max , N): The absolute peak load recorded prior to catastrophic construct failure. ( 2 ) Load at 2mm Displacement (F ( Load at 2mm ) , N): The force required to induce a 2mm gap at the repaired interface. Clinical literature establishes that tissue gaps exceeding 2mm severely hinder microvascular bridging and fibroblast migration, frequently resulting in fibrotic non-union [29] . ( 3 ) Construct Stiffness (N/mm): Calculated from the slope of the linear elastic region of the curve, reflecting the construct's resistance to dynamic deformation. ( 4 ) Failure Mode: Categorized macroscopically into suture breakage, knot slippage, tissue cut-through (cheese-wiring), or a mixed mode. 2.5 Statistical Analysis All quantitative data were analyzed using GraphPad Prism 10. Normality of data distribution and variance homogeneity were formally assessed via Shapiro-Wilk [30]and Levene tests, respectively. Parametric data were analyzed using a One-way ANOVA with Tukey's HSD post-hoc testing for multiple comparisons. Non-parametric data utilized the Kruskal-Wallis H test [31]with Dunn's multiple comparisons. The threshold for statistical significance was defined a priori at P < 0.05. 3. Results 3.1 Phase 1: Biomechanical Properties of Suture Materials The baseline independent testing of the 26 suture specimens revealed highly significant discrepancies in ultimate tensile strength ( Fig. 5 ) , structural stiffness, and failure mechanics across the three materials ( Fig. 6 ) . Kruskal-Wallis non-parametric analysis confirmed a profound overall statistical difference in maximum failure load (P < 0.001). Post-hoc testing demonstrated that the non-absorbable #2 Ethibond (92.44 ± 8.72 N) was significantly stronger than both the absorbable #0 Vicryl (71.76 ± 4.38 N, P = 0.0005) and the 3-0 PGLA (31.80 ± 2.90 N, P = 0.0003). Furthermore, Ethibond exhibited the highest inherent material stiffness (Table 1 ). Regarding failure mechanics, the PGLA group failed entirely via isolated suture breakage, largely attributable to its narrow caliber. Conversely, Vicryl and Ethibond exhibited mixed failure modes. Notably, Vicryl specimens frequently unraveled under tension, demonstrating up to 19 mm of knot slippage prior to ultimate failure. This phenomenon highlights the lower intrinsic knot security of polyglactin materials due to their specific surface friction coefficients. 3.2 Phase 2: Biomechanical Comparison of Suture Configurations Phase 2 testing on the highly standardized porcine surrogate capsular model highlighted a dramatic and statistically significant biomechanical divide between traditional single-strand methods and modern double-strand techniques ( Table 2 ). Within the single-strand baseline cohorts, the Figure-of-8 technique (Group B) moderately outperformed simple interrupted sutures (Group A) in ultimate failure load (60.87 N vs. 54.19 N), achieving a 12% strength augmentation. Furthermore, the Figure-of-8 was slightly faster to tie as a continuous motion [32] . However, double-strand configurations (Groups C and D) exhibited an undeniable mechanical superiority, generating failure loads that nearly doubled those of the single-strand groups. Both the Modified Racking Hitch (100.67 ± 11.48 N) and the Nice knot (104.04 ± 8.68 N) comfortably breached the critical 100 N structural threshold. Crucially, the Nice knot demonstrated the highest structural stiffness across all evaluated cohorts (12.59 ± 1.21 N/mm), vastly outperforming the MRH knot (P < 0.05) (Fig. 7) . This superior stiffness translates directly to minimized elastic elongation and preserved tissue apposition under dynamic loads. Furthermore, the Nice knot achieved these robust biomechanical metrics while maintaining high temporal efficiency during application (183.00 s), saving over a full minute per stitch compared to the highly complex MRH knot (250.12 s) (Fig. 8) . In contrast, while highly effective in enclosed arthroscopic spaces, complex single-strand sliding knots (Duncan loop, SMC knot) failed to provide a mechanical advantage in the open THA surrogate model. Their ultimate failure loads hovered dangerously around 50-55 N, performing no better than basic simple interrupted suturing, yet their application times were exceedingly prolonged, surpassing 220 seconds. The Weston knot (Group E) displayed severe mechanical instability, with failure predominantly characterized by catastrophic knot slippage under tension due to the absence of a secure internal locking mechanism. 4. Discussion The meticulous anatomical reconstruction of the posterior soft tissue complex is universally recognized as a vital surgical safeguard against early dislocation following posterolateral THA [ 14 ].Because the repaired capsular interface undergoes a precarious, months-long physiological healing process, the immediate postoperative phase is fraught with severe mechanical vulnerability. The findings of this rigorous two-stage biomechanical study conclusively demonstrate that the combination of #2 Ethibond and a double-strand Nice knot provides the optimal "Time Zero" mechanical environment required to withstand the high physiological loads induced by early rehabilitation protocols. Phase 1 data emphatically supports the routine use of #2 non-absorbable braided polyester (Ethibond) for capsulotendinous repair in THA [ 21 ].While absorbable sutures (such as Vicryl and PGLA) are frequently lauded for their excellent biocompatibility, their hydrolytic degradation profiles are fundamentally incompatible with the prolonged biological healing timeline of the human hip capsule. During the critical proliferative phase (typically weeks 2–3), nascent Type III collagen networks secreted by fibroblasts lack inherent tensile strength [ 17 , 18 ]. At this exact physiological juncture, polyglactin materials undergo exponential hydrolytic strength decay, creating a dangerous mechanical void [ 21 ].Furthermore, the in vitro testing revealed troubling knot slippage (up to 19 mm) in Vicryl constructs. A tissue gap exceeding 2 mm is physiologically detrimental, as it interrupts microvascular angiogenesis and disrupts fibroblast migration across the repair site, frequently resulting in fibrotic non-union [ 29 ].Ethibond, conversely, bypasses hydrolytic breakdown entirely, effectively shielding the healing tissue from premature mechanical disruption across the entire biological window. The absolute dominance of the Nice knot in Phase 2—breaching 100 N in failure load while delivering unparalleled stiffness (12.59 N/mm)—is grounded in precise physical and geometric mechanics. Fundamentally, the Nice knot is a double-strand, sliding, self-locking configuration [ 16 , 25 ].When subjected to external tension, its unique threading geometry forces the internal core loop to exert immense radial compression. This compression causes the sliding friction between the parallel suture limbs to rise exponentially, triggering an instantaneous, structural "one-way lock” [ 16 ].This robust self-locking trait bypasses the stress relaxation inherent in manually pushed static knots [ 15 ], ensuring that the capsular tissue edges remain intimately apposed. Moreover, construct stiffness is governed by Hooke's Law, representing the structural resistance to elastic deformation. The double-strand parallel architecture of the Nice knot functions mechanically akin to springs arranged in parallel. This configuration strictly curtails the elastic elongation of the suture under physiological loads. By restricting tissue micro-motion to well below the 2 mm safety threshold during early hip flexion, the Nice knot curates an ideal static microenvironment for robust cellular repair [ 16 ]. "Cheese-wiring" (tissue cut-through) represents the predominant failure mode in soft tissue repair under high tension [ 27 ]. The physical mechanism can be accurately modeled by the pressure equation (P = F/A), where P is pressure, F is tensile force, and A is the contact area. In traditional single-strand sutures, the tensile force is highly focused onto a microscopic linear cross-section. When the localized peak pressure exceeds the yield strength of the dense collagen matrix, the suture invariably slices through the tissue [ 24 , 27 ].Both the Figure-of-8 and the Nice knot geometrically double the contact surface area between the high-tensile synthetic material and the biological tissue. This geometric expansion effectively dissipates localized pressure concentration, significantly elevating the construct's resistance to tissue yield [ 32 ]. This study also critically dismantles the prevailing clinical misconception that highly complex knotting techniques inherently yield superior mechanical strength regardless of the surgical environment. Arthroscopic sliding knots (such as the SMC and Duncan loops) are elegantly engineered to deliver tension strictly through narrow cannulas [ 39 ].However, in the deep, unconstrained wound bed of an open THA, surgeons inherently struggle to apply sustained, uniform axial tension to the sliding post. Consequently, asymmetrical tensioning leads to premature locking. These knots offered no mechanical advantage over simple suturing but dramatically increased operative time. For the practicing arthroplasty surgeon, time and strength are inextricably linked to clinical outcomes. Implementing the #2 Ethibond / Nice knot strategy for a standard 3-to-4 stitch posterior repair yields a cumulative pull-out resistance exceeding 300 N—well above the peak physiological loads experienced during early mobilization ( Fig. 9 ) [ 22 ].Concurrently, by saving approximately 1.1 minutes per stitch compared to complex sliding knots, the Nice knot significantly reduces deep wound exposure time. This is highly clinically relevant, as prolonged operative time linearly correlates with exponentially increased risks of periprosthetic joint infection (PJI) [ 33 ]. While the present study rigorously adhered to established biomechanical testing standards, certain methodological limitations exist. Phase 2 utilized healthy porcine dermis to eliminate inter-specimen variability and baseline heterogeneity [ 35 , 36 ].However, human capsular tissue encountered during primary THA is typically sourced from elderly osteoarthritic patients, often characterized by severe fibrotic contractures and advanced collagen degradation [ 38 ].The porcine surrogate is mechanically more robust; thus, the absolute failure loads recorded in this in vitro setting will likely be lower in degenerative human tissue. Nonetheless, by using a highly standardized matrix, the relative mechanical superiority of the double-strand Nice knot remains scientifically unassailable. Furthermore, construct strength was evaluated using quasi-static uniaxial loading, which cannot perfectly replicate the complex, multi-directional shear forces seen in vivo [ 20 ].However, uniaxial tension remains the foundational gold standard for quantifying intrinsic material strength against pure tensile pull-out [ 39 ]. 5. Conclusions Current absorbable sutures and traditional static knots may provide insufficient fixation strength to withstand the high physiological loads generated by early postoperative mobilization. The reconstructive strategy combining #2 Ethibond with the double-strand Nice knot offers optimal initial biomechanical strength ("Time Zero") and unparalleled construct stiffness. This biomechanically optimized approach effectively restricts deleterious tissue gap formation to under 2mm, creating a secure mechanical microenvironment essential for biological healing, and robustly supports the safe implementation of immediate postoperative ERAS protocols in total hip arthroplasty. Declarations Compliance with Ethical Standards Conflict of Interest: The authors declare that they have no conflicts of interest related to the material presented in this manuscript. Ethical Approval: This in vitro biomechanical study utilized commercially sourced porcine dermal tissue obtained from a standard commercial abattoir. The experimental protocol was reviewed and approved by the Institutional Animal Care and Use Committee ( Institution name and approval number are blinded for peer review ). No live animals were utilized or sacrificed specifically for the purposes of this research. Informed Consent: Not applicable. 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Arthroscopy 16:202–207. https://doi.org/10.1016/s0749-8063(00)90034-7 Tables Table 1: Biomechanical properties of the three suture materials evaluated in Phase 1. Material Group Sample Size (n) Maximum Failure Load (Fmax ) [N] Stiffness [N/mm] Total Slippage [mm] Primary Failure Mode Ethibond (Size 2) 7 92.44 ± 8.72 9.0 ± 1.0 6.00 ± 3.51 Mixed (Breakage/Slippage) Vicryl (Size 0) 9 71.76 ± 4.38 8.3 ± 1.5 5.11 ± 5.42 Mixed (High Slippage) PGLA (Size 3-0) 10 31.80 ± 2.90 5.50 ±0.14 3.00 ± 2.21 Suture Breakage Table 2: Biomechanical testing results of the eight suture configurations in Phase 2. Group Method Configuration Suturing Time (s) Load at 2mm Gap (N) Max Failure Load (Fmax ) [N] Stiffness (N/mm) A Simple Single 135.50 ± 34.65 39.77 ± 8.91 54.19 ± 8.24 5.50 ± 1.23 B Figure-of-8 Single 117.75 ± 4.59 45.72 ± 10.92 60.87 ± 6.81 6.32 ± 1.51 C MRH Double 250.12 ± 23.04 87.99 ± 8.15 100.67 ± 11.48 9.91 ± 0.92 D Nice Double 183.00 ± 9.89 91.00 ± 8.78 104.04 ± 8.68 12.59 ± 1.21 E Weston Single 186.57 ± 42.97 38.28 ± 13.74 43.73 ± 9.66 5.29 ± 1.90 F Static Single 171.38 ± 16.33 44.34 ± 5.84 47.00 ± 5.33 6.13 ± 0.81 G Duncan Single 223.38 ± 18.04 35.63 ± 4.79 50.77 ± 12.50 4.93 ± 0.66 H SMC Single 229.12 ± 20.84 44.72 ± 6.91 54.78 ± 5.28 6.18 ± 0.96 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 09 Mar, 2026 Reviewers agreed at journal 06 Mar, 2026 Reviews received at journal 03 Mar, 2026 Reviewers agreed at journal 03 Mar, 2026 Reviewers invited by journal 03 Mar, 2026 Editor assigned by journal 03 Mar, 2026 Submission checks completed at journal 03 Mar, 2026 First submitted to journal 01 Mar, 2026 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-9001769","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":600258689,"identity":"7e44b7cd-ed75-4b39-aed0-10eb14d109bc","order_by":0,"name":"Ming Chen","email":"","orcid":"","institution":"ShenZhen People’s Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ming","middleName":"","lastName":"Chen","suffix":""},{"id":600258690,"identity":"5096e6bc-017d-470b-a182-209fe35e411a","order_by":1,"name":"Xiang Liu","email":"","orcid":"","institution":"ShenZhen People’s Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiang","middleName":"","lastName":"Liu","suffix":""},{"id":600258691,"identity":"71e25748-134d-4218-97b1-e41a8d1ae24e","order_by":2,"name":"Dayi Chen","email":"","orcid":"","institution":"ShenZhen People’s Hospital","correspondingAuthor":false,"prefix":"","firstName":"Dayi","middleName":"","lastName":"Chen","suffix":""},{"id":600258694,"identity":"4d2dcb37-0538-43be-96f2-346f825884a6","order_by":3,"name":"Xiaojing Li","email":"","orcid":"","institution":"ShenZhen People’s Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiaojing","middleName":"","lastName":"Li","suffix":""},{"id":600258697,"identity":"22ee07e3-dc37-4d5e-9b24-77904f93c78c","order_by":4,"name":"Haoyuan Du","email":"","orcid":"","institution":"Beijing Jishuitan Hospital","correspondingAuthor":false,"prefix":"","firstName":"Haoyuan","middleName":"","lastName":"Du","suffix":""},{"id":600258701,"identity":"32fc2d30-afba-408e-ad92-6004023917d9","order_by":5,"name":"Yulong Sun","email":"","orcid":"","institution":"ShenZhen People’s Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yulong","middleName":"","lastName":"Sun","suffix":""},{"id":600258702,"identity":"9f1ea5fa-30a0-484a-9c77-4f6f47f34e07","order_by":6,"name":"Hua Wang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/UlEQVRIiWNgGAWjYJACZhDBxsADomyADBK1pJGghQGi5TBh5QbHzx5+Xdhml9jHf/bg44Jf5+35pJsfMPyo2IZby5m8NOuZbcmJbRJ5ycYz+24ntskcM2DsOXMbpxazAzlmxrxtzEAtPGbSvD23E9gkEgyYGdvwaDn/BqSlPrGN/4z5b96ec/ZsEukf8Gu5kWP8mLftcGIbQ44ZM8+PA4xtEjn4bbG/8Qao8txxY6BKY2neBpCncgoO4vOLZH+O8WeesmrZ+f1nDD/z/LGzl5+RvvHBjwrcWoCATQJIODaAmIxtEKED+NQDAfMHkAMh7D8E1I6CUTAKRsGIBAD6xVRwGDUc0QAAAABJRU5ErkJggg==","orcid":"","institution":"ShenZhen People’s Hospital","correspondingAuthor":true,"prefix":"","firstName":"Hua","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2026-03-01 13:38:02","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9001769/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9001769/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104404962,"identity":"61468275-4e53-41b7-8b27-f2b1f7e8fc3f","added_by":"auto","created_at":"2026-03-11 12:21:27","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":6465694,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagrams of single-strand static controls evaluated in Phase 2: (A) Simple interrupted suture, (B) Figure-of-8 suture.The arrows indicate the direction of tension application for sliding knots.\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/42b5fbec2ae56aad3fdc524d.png"},{"id":104405012,"identity":"d5a0afe7-ca13-4a05-ae0c-7dd0d6815a6a","added_by":"auto","created_at":"2026-03-11 12:21:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":6543588,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagrams of double-strand sliding knots evaluated in Phase 2: (C) Modified Racking Hitch (MRH) knot, (D) Nice knot.\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/fa3861f278d2663c937ba141.png"},{"id":104404990,"identity":"e3a9759a-e3f1-4028-902d-5201b27bf689","added_by":"auto","created_at":"2026-03-11 12:21:32","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":6983770,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagrams of single-strand sliding knots evaluated in Phase 2: (E) Weston knot, (F) Static Surgeon's knot, (G) Duncan loop, (H) SMC knot.\u003c/p\u003e","description":"","filename":"Fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/5acbc86673b1a6aa9da40828.png"},{"id":104258316,"identity":"d99366ae-37dd-417f-a629-fb5d2792ba53","added_by":"auto","created_at":"2026-03-09 17:36:32","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":962570,"visible":true,"origin":"","legend":"\u003cp\u003eExperimental setup and loading process for the in vitro biomechanical testing in Phase 2. (A) Standardized preparation of the porcine dermal surrogate model, with tissue thickness strictly controlled (4.0 ± 0.2 mm) using a digital caliper to ensure baseline consistency. (B) Overview of the microcomputer-controlled universal testing machine and biomechanical testing system used in this study. (C) The sutured specimen is vertically secured in the clamps with a 1.0 N preload applied to eliminate tissue slack. (D) Observation of a typical failure mode during uniaxial quasi-static load-to-failure testing.\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/4a5385802d0000a445be257c.png"},{"id":104258317,"identity":"4b8503da-a455-4717-9b73-231f2454192e","added_by":"auto","created_at":"2026-03-09 17:36:33","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":101982,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of maximum failure load\u0026nbsp; (F\u003csub\u003emax\u003c/sub\u003e, N) among different suture materials in Phase 1. Bar charts represent the mean and standard deviation of each group, while scatter points indicate independent test samples. Kruskal-Wallis nonparametric test with Bonferroni post hoc analysis revealed that the tensile strength of #2 Ethibond was significantly superior to both #0 Vicryl and 3-0 PGLA (P \u0026lt; 0.001 for all pairwise comparisons). This indicates that the non-absorbable polyester suture (Ethibond) provides a statistically significant advantage in initial fixation strength over absorbable sutures (Vicryl and PGLA), offering more reliable initial biomechanical stability for posterior soft tissue repair.\u003c/p\u003e","description":"","filename":"Fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/2213f8a4360e14120802e778.png"},{"id":104258323,"identity":"0a479473-ea52-43ef-aebf-e4bf67ebf04d","added_by":"auto","created_at":"2026-03-09 17:36:33","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":438045,"visible":true,"origin":"","legend":"\u003cp\u003eMacroscopic morphological comparison of sutures after uniaxial load-to-failure testing in Phase 1. Local close-ups illustrate the typical failure modes of the three suture materials: (A) The 3-0 PGLA suture exhibited simple breakage with a tight knot structure and no obvious slippage. (B) The #0 Vicryl suture showed significant knot slippage and structural deformation (the arrow indicates the elongated tail pulled out under high tension), visually confirming its lower knot security. (C) The #2 Ethibond suture demonstrated a mixed failure mode of breakage combined with partial slippage (arrow). This figure intuitively confirms the significant impact of material mechanical properties and surface friction coefficients on the initial stability of the repair.\u003c/p\u003e","description":"","filename":"Fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/09d873afdc3b9843ab137b05.png"},{"id":104405199,"identity":"df64b689-3619-4e5f-ae56-9582743c4623","added_by":"auto","created_at":"2026-03-11 12:22:05","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":129578,"visible":true,"origin":"","legend":"\u003cp\u003eBox plot of construct stiffness distribution across all groups in Phase 2. The boxes display the median and interquartile range, while the superimposed jittered scatter points show the original distribution of independent samples. Comparisons reveal that the double-strand techniques—MRH knot (Group C) and Nice knot (Group D)—occupy the highest tier of stiffness, outperforming single-strand techniques overall. In the context of posterior soft tissue repair following total hip arthroplasty (THA), the clinical significance of this high stiffness is minimal elastic deformation under tension. During early postoperative rehabilitation (e.g., sitting or hip flexion), high stiffness effectively resists micro-motion and prevents gap formation greater than 2mm (diastasis), creating a stable microenvironment ideal for fibroblast migration and collagen cross-linking, thus substantially reducing the risk of non-union caused by repetitive micro-motion.\u003c/p\u003e","description":"","filename":"Fig7.png","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/87a720166f2883a79b99d94d.png"},{"id":104258321,"identity":"f914dfa2-729e-4939-bce1-5f80c71549f2","added_by":"auto","created_at":"2026-03-09 17:36:33","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":173426,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plot of the surgical efficiency matrix for each suturing technique. The horizontal axis represents suturing time (s), and the vertical axis represents maximum failure load (N). The dashed lines indicate the medians for suturing time and load across the entire sample, dividing the matrix into four quadrants. The upper-left quadrant represents the ideal clinical scenario: \"high strength, short time.\" The double-strand Nice knot (Group D, square scatter points) predominantly falls within this ideal region. This demonstrates that the Nice knot significantly enhances surgical efficiency while providing excellent pull-out strength comparable to the Modified Racking Hitch (MRH knot, Group C). Its unique self-locking mechanism allows the surgeon to quickly tighten the knot without an assistant to maintain tension. Assuming a standard 3 to 4 stitches for posterior repair in THA, the Nice knot can save approximately 3.5 to 4.5 minutes compared to complex sliding knots. At the end of the surgery, this reduction in deep wound exposure time directly mitigates the risk of periprosthetic joint infection (PJI), optimizing overall surgical safety while ensuring biomechanical robustness.\u003c/p\u003e","description":"","filename":"Fig8.png","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/dcd642975d81e56724ccd1ee.png"},{"id":104258325,"identity":"cede88dc-5ca5-4d33-bcd4-3a1e5581eb62","added_by":"auto","created_at":"2026-03-09 17:36:33","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":21166745,"visible":true,"origin":"","legend":"\u003cp\u003eIntraoperative image of layer-by-layer posterior soft tissue reconstruction using the recommended protocol in total hip arthroplasty. The image clearly shows the surgeon utilizing #2 Ethibond non-absorbable sutures to achieve a secure closure of the incised posterior capsule with three double-strand Nice knots. This repair strategy provides exceptional initial biomechanical strength (\"Time Zero\") and establishes a solid anatomical and mechanical foundation for the patient to safely achieve immediate postoperative mobilization under Enhanced Recovery After Surgery (ERAS) protocols.\u003c/p\u003e","description":"","filename":"Fig9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/3f363ba9d96ff6ba3ca25341.jpg"},{"id":104409391,"identity":"a0e137fb-7a80-4edb-a476-50f59ea86000","added_by":"auto","created_at":"2026-03-11 12:44:57","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":39750478,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9001769/v1/0d594284-416c-451a-8ce0-6b53f9d37de9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Optimizing Initial Biomechanical Strength (\"Time Zero\") of Posterior Repair in Total Hip Arthroplasty: A Biomechanical Comparison of Suture Materials and Knot Configurations","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eIn the contemporary landscape of orthopedic surgery, total hip arthroplasty (THA) stands as a highly successful intervention for reliably alleviating pain and restoring joint kinematics in patients afflicted with severe hip pathologies [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].With continuous advancements in bearing tribology and prosthesis design, THA currently achieves exceptional long-term survivorship [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].However, driven by a globally aging demographic and a corresponding surge in surgical volume, early postoperative dislocation remains a formidable and devastating complication [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].Dislocation profoundly impairs the patient's quality of life and imposes a severe socioeconomic burden, as recurrent instability often necessitates complex surgical revisions and prolonged hospital readmissions [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].Therefore, establishing robust, evidence-based strategies to mitigate the risk of early dislocation remains an urgent priority in arthroplasty research.\u003c/p\u003e \u003cp\u003eThe surgical approach is inextricably linked to the intrinsic risk of postoperative instability. The posterolateral approach is globally favored by arthroplasty surgeons due to its excellent anatomical exposure, preservation of the critical hip abductor mechanism, and facilitation of precise component positioning [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].However, this trajectory inherently demands the transection of the short external rotator muscles and the posterior articular capsule [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].The native hip capsule is a highly sophisticated biomechanical restraint system. The posterior soft tissue complex (PSTC) provides the primary tensile restraint when the hip is subjected to the high-risk position of flexion, adduction, and internal rotation [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].Its iatrogenic absence drastically compromises posterior stability, rendering the femoral head highly susceptible to posterior subluxation [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Historical literature indicates that if the posterior soft tissues are left unrepaired, the early dislocation rate can soar to an unacceptable 4% to 9% [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSubstantial evidence-based literature confirms that meticulous anatomical reconstruction of the posterior structures through enhanced posterior capsule repair (PCR) significantly bolsters the dislocation resistance torque, restores proprioception, and effectively reduces dislocation rates [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].Nevertheless, clinical follow-ups reveal that a subset of patients still experience early dislocation despite receiving meticulously executed PCR [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].Advanced imaging and biomechanical investigations indicate that these \"failed repairs\" rarely result from the native host tissue tearing. Instead, failure typically originates at the \"weak link\" within the exogenous repair construct\u0026mdash;the suture-knot interface [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].Biomechanical investigations underscore that merely placing sutures does not guarantee clinical success [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe structural repair of the capsule and short external rotators fundamentally relies on a complex biological healing cascade that requires 6 to 12 weeks to mature. During the initial inflammatory phase, the local tissue environment is catabolic, and inherent mechanical holding power drops to its absolute nadir [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].In the subsequent proliferative phase, fibroblasts secrete weak, uncross-linked Type III collagen [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].Conversely, modern Enhanced Recovery After Surgery (ERAS) protocols mandate immediate postoperative mobilization, often within hours of surgery [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].Consequently, the entire physiological load of early rehabilitation is borne exclusively by the synthetic suture material and the spatial geometry of the knot construct. Thus, the initial biomechanical strength\u0026mdash;or \"Time Zero\" strength\u0026mdash;achieved on the operating table serves as the final mechanical safeguard against early dislocation.\u003c/p\u003e \u003cp\u003eTo address the persistent risk of early dislocation and navigate the rigorous biomechanical demands of the soft tissue healing phase under ERAS pathways, the present study utilizes a highly standardized in vitro surrogate model to conduct rigorous biomechanical tensile testing. The specific objectives are to: (1) evaluate and quantify the intrinsic tensile properties of clinically prevalent suture materials; (2) systematically evaluate the ultimate strength, construct stiffness, and failure modes of eight distinct knot configurations; and (3) synthesize these empirical findings to formulate an optimal, evidence-based posterior soft tissue repair algorithm that maximizes \"Time Zero\" stability.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cp\u003e\u003cstrong\u003e2.1 Overview of Experimental Design\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe in vitro biomechanical testing protocol was meticulously designed in two progressive phases to isolate specific mechanical variables. Phase 1 evaluated the baseline tensile properties of different suture materials independently, establishing material-specific mechanical baselines without tissue confounding factors. Phase 2 utilized a highly standardized soft tissue surrogate to evaluate the comprehensive biomechanical efficacy of eight distinct suture-knot configurations in a simulated surgical environment. All tests were conducted in a climate-controlled biomechanics laboratory at 25\u0026deg;C using a microcomputer-controlled universal testing machine (PDDW-2; Jinan Pinde Testing Machine Co., Ltd.).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Phase 1: Baseline Mechanical Properties of Suture Materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThree clinically prevalent sutures were tested to assess their intrinsic tensile performance and inherent knot security:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.Ethibond Group (n=7):\u0026nbsp;\u003c/strong\u003eSize #2 braided polyester non-absorbable suture.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.Vicryl Group (n=9):\u003c/strong\u003e Size #0 braided polyglactin 910 absorbable suture.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.PGLA Group (n=10):\u0026nbsp;\u003c/strong\u003eSize 3-0 braided polyglycolic acid absorbable suture.\u003c/p\u003e\n\u003cp\u003eAll specimens were manually tied into closed loops using a standardized surgical knot configuration featuring three locking throws. This technique was employed to eliminate operator-induced knot slippage as a confounding variable, effectively isolating the intrinsic tensile strength and surface friction coefficient of the materials themselves.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Phase 2: Biomechanical Comparison of Suture Configurations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eObtaining fresh, homogeneous human cadaveric hip capsules is logistically challenging and scientifically problematic; such specimens invariably exhibit severe age-related collagen degeneration, macroscopic structural defects, and vast inter-specimen variability, which severely confounds baseline variables [19].Therefore, porcine dermal skin was utilized as a scientifically validated and highly standardized surrogate model. Porcine dermis is histologically analogous to dense human capsular connective tissue, featuring an interwoven network of Type I and III collagen fibers that accurately replicate the \u0026quot;cheese-wiring\u0026quot; (suture cut-through) resistance of the human hip capsule [35, 36] .\u003c/p\u003e\n\u003cp\u003eStrict standardization protocols were enforced during specimen preparation. Dermis was harvested uniformly from the dorsum of age-matched domestic pigs and precisely sectioned into 100 mm \u0026times; 30 mm strips. A high-precision digital caliper was utilized to ensure a strict thickness tolerance of 4.0\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026plusmn;\u0026nbsp;\u003c/span\u003e0.2 mm across all specimens. A central, full-thickness transverse incision was created with a #11 scalpel blade to mechanically simulate a surgical capsulotomy. The simulated capsular edges were approximated for suturing, and physiological tissue hydration was continuously maintained utilizing a 0.9% saline spray to accurately replicate in vivo viscoelasticity and fluid mechanics [28] .\u003c/p\u003e\n\u003cp\u003eEight distinct knot configurations were evaluated, categorized as follows:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.Single-Strand Static Controls\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(Fig. 1):\u0026nbsp;\u003c/strong\u003eGroup A (Simple Interrupted), Group B (Figure-of-8).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2. Double-Strand Sliding Knots (Fig. 2):\u003c/strong\u003e Group C (Modified Racking Hitch \u0026ndash; MRH [26] ), Group D (Nice knot [25] ).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3. Single-Strand Sliding Knots (Fig. 3):\u0026nbsp;\u003c/strong\u003eGroup E (Weston knot), Group F (Static Surgeon\u0026apos;s knot), Group G (Duncan loop), Group H (SMC knot [23] ).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4 Biomechanical Testing Protocol\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePhase 2 constructs underwent immediate \u0026quot;Time Zero\u0026quot; tensile testing (\u003cstrong\u003eFig. 4\u003c/strong\u003e)\u0026nbsp;following preparation. Specimens were mounted vertically within the testing machine clamps. A 1.0 N preload was applied for 10 seconds to systematically eliminate viscoelastic slack and uniformize the tissue fibers, defining the strict zero-displacement baseline. Quasistatic uniaxial tension was then applied at a constant displacement rate of 20 mm/min until catastrophic structural failure occurred.\u003c/p\u003e\n\u003cp\u003eCore biomechanical parameters extracted from the continuous load-displacement curves included:\u003c/p\u003e\n\u003cp\u003e(\u003cstrong\u003e1\u003c/strong\u003e)\u003cstrong\u003eMaximum Failure Load (F\u003c/strong\u003e\u003cstrong\u003e\u003csub\u003emax\u003c/sub\u003e\u003c/strong\u003e\u003cstrong\u003e, N):\u0026nbsp;\u003c/strong\u003eThe absolute peak load recorded prior to catastrophic construct failure.\u003c/p\u003e\n\u003cp\u003e(\u003cstrong\u003e2\u003c/strong\u003e)\u003cstrong\u003eLoad at 2mm Displacement\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(F\u003c/strong\u003e(\u003cstrong\u003eLoad at 2mm\u003c/strong\u003e)\u003cstrong\u003e, N):\u003c/strong\u003e The force required to induce a 2mm gap at the repaired interface. Clinical literature establishes that tissue gaps exceeding 2mm severely hinder microvascular bridging and fibroblast migration, frequently resulting in fibrotic non-union [29] .\u003c/p\u003e\n\u003cp\u003e(\u003cstrong\u003e3\u003c/strong\u003e)\u003cstrong\u003eConstruct Stiffness (N/mm):\u0026nbsp;\u003c/strong\u003eCalculated from the slope of the linear elastic region of the curve, reflecting the construct\u0026apos;s resistance to dynamic deformation.\u003c/p\u003e\n\u003cp\u003e(\u003cstrong\u003e4\u003c/strong\u003e)\u003cstrong\u003eFailure Mode:\u0026nbsp;\u003c/strong\u003eCategorized macroscopically into suture breakage, knot slippage, tissue cut-through (cheese-wiring), or a mixed mode.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5 Statistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll quantitative data were analyzed using GraphPad Prism 10. Normality of data distribution and variance homogeneity were formally assessed via Shapiro-Wilk [30]and Levene tests, respectively. Parametric data were analyzed using a One-way ANOVA with Tukey\u0026apos;s HSD post-hoc testing for multiple comparisons. Non-parametric data utilized the Kruskal-Wallis H test [31]with Dunn\u0026apos;s multiple comparisons. The threshold for statistical significance was defined a priori at P \u0026lt; 0.05.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003e\u003cstrong\u003e3.1 Phase 1: Biomechanical Properties of Suture Materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe baseline independent testing of the 26 suture specimens revealed highly significant discrepancies in ultimate tensile strength (\u003cstrong\u003eFig. 5\u003c/strong\u003e)\u0026nbsp;, structural stiffness, and failure mechanics \u0026nbsp;across the three materials (\u003cstrong\u003eFig. 6\u003c/strong\u003e) . Kruskal-Wallis non-parametric analysis confirmed a profound overall statistical difference in maximum failure load (P \u0026lt; 0.001). Post-hoc testing demonstrated that the non-absorbable #2 Ethibond (92.44\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026plusmn;\u0026nbsp;\u003c/span\u003e8.72 N) was significantly stronger than both the absorbable #0 Vicryl (71.76\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026plusmn;\u0026nbsp;\u003c/span\u003e4.38 N, P = 0.0005) and the 3-0 PGLA (31.80\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026plusmn;\u0026nbsp;\u003c/span\u003e2.90 N, P = 0.0003). Furthermore, Ethibond exhibited the highest inherent material stiffness\u0026nbsp;\u003cstrong\u003e(Table 1\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003eRegarding failure mechanics, the PGLA group failed entirely via isolated suture breakage, largely attributable to its narrow caliber. Conversely, Vicryl and Ethibond exhibited mixed failure modes. Notably, Vicryl specimens frequently unraveled under tension, demonstrating up to 19 mm of knot slippage prior to ultimate failure. This phenomenon highlights the lower intrinsic knot security of polyglactin materials due to their specific surface friction coefficients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 Phase 2: Biomechanical Comparison of Suture Configurations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePhase 2 testing on the highly standardized porcine surrogate capsular model highlighted a dramatic and statistically significant biomechanical divide between traditional single-strand methods and modern double-strand techniques (\u003cstrong\u003eTable 2\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003eWithin the single-strand baseline cohorts, the Figure-of-8 technique (Group B) moderately outperformed simple interrupted sutures (Group A) in ultimate failure load (60.87 N vs. 54.19 N), achieving a 12% strength augmentation. Furthermore, the Figure-of-8 was slightly faster to tie as a continuous motion [32] .\u003c/p\u003e\n\u003cp\u003eHowever, double-strand configurations (Groups C and D) exhibited an undeniable mechanical superiority, generating failure loads that nearly doubled those of the single-strand groups. Both the Modified Racking Hitch (100.67\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026plusmn;\u0026nbsp;\u003c/span\u003e11.48 N) and the Nice knot (104.04\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026plusmn;\u0026nbsp;\u003c/span\u003e8.68 N) comfortably breached the critical 100 N structural threshold. Crucially, the Nice knot demonstrated the highest structural stiffness across all evaluated cohorts (12.59\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026plusmn;\u0026nbsp;\u003c/span\u003e1.21 N/mm), vastly outperforming the MRH knot (P \u0026lt; 0.05)\u0026nbsp;\u003cstrong\u003e(Fig. 7)\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e. This superior stiffness translates directly to minimized elastic elongation and preserved tissue apposition under dynamic loads.\u003c/p\u003e\n\u003cp\u003eFurthermore, the Nice knot achieved these robust biomechanical metrics while maintaining high temporal efficiency during application (183.00 s), saving over a full minute per stitch compared to the highly complex MRH knot (250.12 s)\u0026nbsp;\u003cstrong\u003e(Fig. 8)\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003eIn contrast, while highly effective in enclosed arthroscopic spaces, complex single-strand sliding knots (Duncan loop, SMC knot) failed to provide a mechanical advantage in the open THA surrogate model. Their ultimate failure loads hovered dangerously around 50-55 N, performing no better than basic simple interrupted suturing, yet their application times were exceedingly prolonged, surpassing 220 seconds. The Weston knot (Group E) displayed severe mechanical instability, with failure predominantly characterized by catastrophic knot slippage under tension due to the absence of a secure internal locking mechanism.\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThe meticulous anatomical reconstruction of the posterior soft tissue complex is universally recognized as a vital surgical safeguard against early dislocation following posterolateral THA [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].Because the repaired capsular interface undergoes a precarious, months-long physiological healing process, the immediate postoperative phase is fraught with severe mechanical vulnerability. The findings of this rigorous two-stage biomechanical study conclusively demonstrate that the combination of #2 Ethibond and a double-strand Nice knot provides the optimal \"Time Zero\" mechanical environment required to withstand the high physiological loads induced by early rehabilitation protocols.\u003c/p\u003e \u003cp\u003ePhase 1 data emphatically supports the routine use of #2 non-absorbable braided polyester (Ethibond) for capsulotendinous repair in THA [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].While absorbable sutures (such as Vicryl and PGLA) are frequently lauded for their excellent biocompatibility, their hydrolytic degradation profiles are fundamentally incompatible with the prolonged biological healing timeline of the human hip capsule. During the critical proliferative phase (typically weeks 2\u0026ndash;3), nascent Type III collagen networks secreted by fibroblasts lack inherent tensile strength [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. At this exact physiological juncture, polyglactin materials undergo exponential hydrolytic strength decay, creating a dangerous mechanical void [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].Furthermore, the in vitro testing revealed troubling knot slippage (up to 19 mm) in Vicryl constructs. A tissue gap exceeding 2 mm is physiologically detrimental, as it interrupts microvascular angiogenesis and disrupts fibroblast migration across the repair site, frequently resulting in fibrotic non-union [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].Ethibond, conversely, bypasses hydrolytic breakdown entirely, effectively shielding the healing tissue from premature mechanical disruption across the entire biological window.\u003c/p\u003e \u003cp\u003eThe absolute dominance of the Nice knot in Phase 2\u0026mdash;breaching 100 N in failure load while delivering unparalleled stiffness (12.59 N/mm)\u0026mdash;is grounded in precise physical and geometric mechanics. Fundamentally, the Nice knot is a double-strand, sliding, self-locking configuration [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].When subjected to external tension, its unique threading geometry forces the internal core loop to exert immense radial compression. This compression causes the sliding friction between the parallel suture limbs to rise exponentially, triggering an instantaneous, structural \"one-way lock\u0026rdquo; [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].This robust self-locking trait bypasses the stress relaxation inherent in manually pushed static knots [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], ensuring that the capsular tissue edges remain intimately apposed.\u003c/p\u003e \u003cp\u003eMoreover, construct stiffness is governed by Hooke's Law, representing the structural resistance to elastic deformation. The double-strand parallel architecture of the Nice knot functions mechanically akin to springs arranged in parallel. This configuration strictly curtails the elastic elongation of the suture under physiological loads. By restricting tissue micro-motion to well below the 2 mm safety threshold during early hip flexion, the Nice knot curates an ideal static microenvironment for robust cellular repair [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e\"Cheese-wiring\" (tissue cut-through) represents the predominant failure mode in soft tissue repair under high tension [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. The physical mechanism can be accurately modeled by the pressure equation (P\u0026thinsp;=\u0026thinsp;F/A), where P is pressure, F is tensile force, and A is the contact area. In traditional single-strand sutures, the tensile force is highly focused onto a microscopic linear cross-section. When the localized peak pressure exceeds the yield strength of the dense collagen matrix, the suture invariably slices through the tissue [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].Both the Figure-of-8 and the Nice knot geometrically double the contact surface area between the high-tensile synthetic material and the biological tissue. This geometric expansion effectively dissipates localized pressure concentration, significantly elevating the construct's resistance to tissue yield [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study also critically dismantles the prevailing clinical misconception that highly complex knotting techniques inherently yield superior mechanical strength regardless of the surgical environment. Arthroscopic sliding knots (such as the SMC and Duncan loops) are elegantly engineered to deliver tension strictly through narrow cannulas [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].However, in the deep, unconstrained wound bed of an open THA, surgeons inherently struggle to apply sustained, uniform axial tension to the sliding post. Consequently, asymmetrical tensioning leads to premature locking. These knots offered no mechanical advantage over simple suturing but dramatically increased operative time.\u003c/p\u003e \u003cp\u003eFor the practicing arthroplasty surgeon, time and strength are inextricably linked to clinical outcomes. Implementing the #2 Ethibond / Nice knot strategy for a standard 3-to-4 stitch posterior repair yields a cumulative pull-out resistance exceeding 300 N\u0026mdash;well above the peak physiological loads experienced during early mobilization \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].Concurrently, by saving approximately 1.1 minutes per stitch compared to complex sliding knots, the Nice knot significantly reduces deep wound exposure time. This is highly clinically relevant, as prolonged operative time linearly correlates with exponentially increased risks of periprosthetic joint infection (PJI) [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWhile the present study rigorously adhered to established biomechanical testing standards, certain methodological limitations exist. Phase 2 utilized healthy porcine dermis to eliminate inter-specimen variability and baseline heterogeneity [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].However, human capsular tissue encountered during primary THA is typically sourced from elderly osteoarthritic patients, often characterized by severe fibrotic contractures and advanced collagen degradation [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e].The porcine surrogate is mechanically more robust; thus, the absolute failure loads recorded in this in vitro setting will likely be lower in degenerative human tissue. Nonetheless, by using a highly standardized matrix, the relative mechanical superiority of the double-strand Nice knot remains scientifically unassailable. Furthermore, construct strength was evaluated using quasi-static uniaxial loading, which cannot perfectly replicate the complex, multi-directional shear forces seen in vivo [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].However, uniaxial tension remains the foundational gold standard for quantifying intrinsic material strength against pure tensile pull-out [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eCurrent absorbable sutures and traditional static knots may provide insufficient fixation strength to withstand the high physiological loads generated by early postoperative mobilization. The reconstructive strategy combining #2 Ethibond with the double-strand Nice knot offers optimal initial biomechanical strength (\"Time Zero\") and unparalleled construct stiffness. This biomechanically optimized approach effectively restricts deleterious tissue gap formation to under 2mm, creating a secure mechanical microenvironment essential for biological healing, and robustly supports the safe implementation of immediate postoperative ERAS protocols in total hip arthroplasty.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompliance with Ethical Standards\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest:\u0026nbsp;\u003c/strong\u003eThe authors declare that they have no conflicts of interest related to the material presented in this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval:\u0026nbsp;\u003c/strong\u003eThis in vitro biomechanical study utilized commercially sourced porcine dermal tissue obtained from a standard commercial abattoir. The experimental protocol was reviewed and approved by the Institutional Animal Care and Use Committee (\u003cstrong\u003eInstitution name and approval number are blinded for peer review\u003c/strong\u003e). No live animals were utilized or sacrificed specifically for the purposes of this research.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed Consent:\u0026nbsp;\u003c/strong\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eThe authors declare that no specific funding was received for the design, execution, or preparation of this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability:\u0026nbsp;\u003c/strong\u003eThe datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLearmonth ID, Young C, Rorabeck C (2007) The operation of the century: total hip replacement. 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Arthroscopy 16:202\u0026ndash;207. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/s0749-8063(00)90034-7\u003c/span\u003e\u003cspan address=\"10.1016/s0749-8063(00)90034-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1: Biomechanical properties of the three suture materials evaluated in Phase 1.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"643\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003eMaterial Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003eSample Size (n)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 167px;\"\u003e\n \u003cp\u003eMaximum Failure Load (Fmax ) [N]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003eStiffness [N/mm]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eTotal Slippage [mm]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003ePrimary Failure Mode\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003eEthibond (Size 2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 167px;\"\u003e\n \u003cp\u003e92.44 \u0026plusmn; 8.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e9.0 \u0026plusmn; 1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e6.00 \u0026plusmn; 3.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003eMixed (Breakage/Slippage)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003eVicryl \u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(Size 0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 167px;\"\u003e\n \u003cp\u003e71.76 \u0026plusmn; 4.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e8.3 \u0026plusmn; 1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e5.11 \u0026plusmn; 5.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003eMixed\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;(High Slippage)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003ePGLA \u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(Size 3-0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 167px;\"\u003e\n \u003cp\u003e31.80 \u0026plusmn; 2.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e5.50 \u0026plusmn;0.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e3.00 \u0026plusmn; 2.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003eSuture Breakage\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2: Biomechanical testing results of the eight suture configurations in\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003ePhase 2.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"635\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eGroup\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003eMethod\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eConfiguration\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003eSuturing Time \u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003eLoad at 2mm Gap (N)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 127px;\"\u003e\n \u003cp\u003eMax Failure Load\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;(Fmax ) [N]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003eStiffness\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;(N/mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003eSimple\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eSingle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e135.50 \u0026plusmn; 34.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e39.77 \u0026plusmn; 8.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 127px;\"\u003e\n \u003cp\u003e54.19 \u0026plusmn; 8.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e5.50 \u0026plusmn; 1.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003eFigure-of-8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eSingle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e117.75 \u0026plusmn; 4.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e45.72 \u0026plusmn; 10.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 127px;\"\u003e\n \u003cp\u003e60.87 \u0026plusmn; 6.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e6.32 \u0026plusmn; 1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003eMRH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eDouble\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e250.12 \u0026plusmn; 23.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e87.99 \u0026plusmn; 8.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 127px;\"\u003e\n \u003cp\u003e100.67 \u0026plusmn; 11.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e9.91 \u0026plusmn; 0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003eNice\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eDouble\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e183.00 \u0026plusmn; 9.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e91.00 \u0026plusmn; 8.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 127px;\"\u003e\n \u003cp\u003e104.04 \u0026plusmn; 8.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e12.59 \u0026plusmn; 1.21\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003eWeston\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eSingle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e186.57 \u0026plusmn; 42.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e38.28 \u0026plusmn; 13.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 127px;\"\u003e\n \u003cp\u003e43.73 \u0026plusmn; 9.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e5.29 \u0026plusmn; 1.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003eStatic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eSingle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e171.38 \u0026plusmn; 16.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e44.34 \u0026plusmn; 5.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 127px;\"\u003e\n \u003cp\u003e47.00 \u0026plusmn; 5.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e6.13 \u0026plusmn; 0.81\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eG\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003eDuncan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eSingle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e223.38 \u0026plusmn; 18.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e35.63 \u0026plusmn; 4.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 127px;\"\u003e\n \u003cp\u003e50.77 \u0026plusmn; 12.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e4.93 \u0026plusmn; 0.66\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003eSMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eSingle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e229.12 \u0026plusmn; 20.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e44.72 \u0026plusmn; 6.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 127px;\"\u003e\n \u003cp\u003e54.78 \u0026plusmn; 5.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e6.18 \u0026plusmn; 0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\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":"archives-of-orthopaedic-and-trauma-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aots","sideBox":"Learn more about [Archives of Orthopaedic and Trauma Surgery](http://link.springer.com/journal/402)","snPcode":"402","submissionUrl":"https://submission.springernature.com/new-submission/402/3","title":"Archives of Orthopaedic and Trauma Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Total Hip Arthroplasty, Biomechanics, Posterior Soft Tissue Repair, Suture Techniques, Nice Knot, Enhanced Recovery After Surgery","lastPublishedDoi":"10.21203/rs.3.rs-9001769/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9001769/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eIntroduction:\u003c/h2\u003e \u003cp\u003ePosterior soft tissue repair (PCR) is recognized as a critical procedural step for mitigating early dislocation following total hip arthroplasty (THA) performed via the posterolateral approach. However, biological healing of the capsulotendinous structures typically requires 6 to 12 weeks, creating a prolonged window of mechanical vulnerability. Concurrently, the increasing implementation of Enhanced Recovery After Surgery (ERAS) protocols demands immediate postoperative mobilization. Consequently, the initial biomechanical strength\u0026mdash;often referred to as \"Time Zero\" strength\u0026mdash;of the repair construct serves as the primary defense against construct failure. This study aims to identify the optimal suture material and knot configuration to maximize initial repair stability and safely facilitate aggressive early rehabilitation.\u003c/p\u003e\u003ch2\u003eMaterials and methods\u003c/h2\u003e \u003cp\u003eThis in vitro biomechanical study was conducted in two sequential phases. Phase 1 evaluated the baseline tensile properties of three prevalent suture materials: #2 Ethibond, #0 Vicryl, and 3\u0026thinsp;\u0026minus;\u0026thinsp;0 PGLA. Phase 2 utilized a standardized porcine dermal surrogate to accurately model the human posterior capsule, effectively controlling for the biological heterogeneity of human cadaveric tissue. Eight distinct suture configurations, encompassing both single- and double-strand methods, were rigorously compared. Key biomechanical metrics extracted from uniaxial quasi-static load-to-failure testing included maximum failure load, load at 2mm gap formation, and construct stiffness.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003ePhase 1 demonstrated that the non-absorbable #2 Ethibond possessed significantly superior ultimate tensile strength (92.44\u0026thinsp;\u0026plusmn;\u0026thinsp;8.72 N) and structural stiffness compared to the absorbable alternatives (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001). In Phase 2, double-strand configurations significantly outperformed all single-strand techniques. Specifically, the double-strand Nice knot achieved a maximum failure load of 104.04\u0026thinsp;\u0026plusmn;\u0026thinsp;8.68 N, nearly double that of the conventional simple interrupted suture (54.19\u0026thinsp;\u0026plusmn;\u0026thinsp;8.24 N). Furthermore, the Nice knot exhibited the highest construct stiffness (12.59\u0026thinsp;\u0026plusmn;\u0026thinsp;1.21 N/mm), providing superior resistance to deleterious tissue gap formation, while requiring significantly less operative time (183\u0026thinsp;\u0026plusmn;\u0026thinsp;9.89 s) compared to complex arthroscopic sliding knots (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eCurrent absorbable sutures and traditional static knots provide insufficient fixation strength to withstand the physiological loads generated by early mobilization. A reconstructive strategy combining #2 Ethibond with a double-strand Nice knot offers optimal \"Time Zero\" biomechanical strength and high stiffness. This construct effectively restricts tissue gap formation to under the 2mm safety threshold, creating a secure mechanical microenvironment for biological healing and robustly supporting the implementation of immediate postoperative ERAS protocols.\u003c/p\u003e","manuscriptTitle":"Optimizing Initial Biomechanical Strength (\"Time Zero\") of Posterior Repair in Total Hip Arthroplasty: A Biomechanical Comparison of Suture Materials and Knot Configurations","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-09 17:36:27","doi":"10.21203/rs.3.rs-9001769/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-09T14:39:56+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"90812028871969152144672178814150857735","date":"2026-03-06T22:13:41+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-04T00:10:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"196971220412817544486730535296015003669","date":"2026-03-03T22:06:51+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-03T19:08:29+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-03T17:16:05+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-03T07:25:02+00:00","index":"","fulltext":""},{"type":"submitted","content":"Archives of Orthopaedic and Trauma Surgery","date":"2026-03-01T13:21:04+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"archives-of-orthopaedic-and-trauma-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aots","sideBox":"Learn more about [Archives of Orthopaedic and Trauma Surgery](http://link.springer.com/journal/402)","snPcode":"402","submissionUrl":"https://submission.springernature.com/new-submission/402/3","title":"Archives of Orthopaedic and Trauma Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"c06a2f61-5fd3-4394-8df6-9461ecf06d9c","owner":[],"postedDate":"March 9th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-16T11:23:48+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-09 17:36:27","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9001769","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9001769","identity":"rs-9001769","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}