The MAASH Technique in Total Hip Arthroplasty: A 15-Year Retrospective Study of 671 Cases without Dislocation and controlled leg length discrepancy

The MAASH Technique in Total Hip Arthroplasty: A 15-Year Retrospective Study of 671 Cases without Dislocation and controlled leg length discrepancy | 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 The MAASH Technique in Total Hip Arthroplasty: A 15-Year Retrospective Study of 671 Cases without Dislocation and controlled leg length discrepancy Albert Broch, Ester Navarro-Cano, Francisco Reina, Felipe G. Delgado, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7100131/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Background Dislocation and leg length discrepancy (LLD) are persistent challenges in Total Hip Replacement (THR), contributing to patient dissatisfaction and increased revision rates. The MAASH technique, a modification of the Hardinge direct lateral approach, preserves anterior capsular ligaments through a selective capsulotomy known as the MAASH Window. This study evaluates the long-term outcomes of the MAASH technique over a 15-year period. Methods A retrospective observational study included 671 consecutive primary THRs performed using the MAASH technique between 2010 and 2025. Radiographic analysis comprised acetabular component positioning and leg length measurements. Net leg length discrepancy (netLLD) was defined as the postoperative minus preoperative LLD, adjusted for radiographic magnification. Statistical analysis was performed using ANOVA, t-tests, and regression, with significance set at p < 0.05. Results No dislocations were reported during the 15-year span of this study. The mean netLLD was 4.8 mm (SD 4.1), with discrepancies ≤10 mm in 89.9% of cases and ≤6 mm in 78.3%. Acetabular component positioning fell within conventional safe zone parameters. A total of 25 complications (3.7%) were recorded, including periprosthetic fractures (1.5%), infections (1.3%), and aseptic loosening (0.6%). Longer surgical time (>100 minutes) was significantly associated with higher complication rates (p<0.0001). Conclusions The MAASH technique provides reliable stability and leg length control in primary THR, with zero dislocations and reduced leg length discrepancy in comparison with previous studies. Capsular preservation may play a key role in enhancing biomechanical outcomes without the need for constrained or dual mobility implants. Hip stability prostheses MAASH leg length discrepancy Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 BACKGROUND Leg length discrepancy (LLD) and dislocation following total hip replacement (THR) remain two of the most challenging and widely discussed complications in orthopedic surgery worldwide, with significant impact on patient satisfaction and healthcare burden. Hip capsular ligaments provide essential passive stabilization, particularly at the limits of hip motion, preventing edge loading and contributing to joint security across the full range of motion[ 1 ]. Numerous surgical approaches have been developed for primary THR, but most of them involve partial or complete release of the hip joint capsule, thereby weakening its stabilizing function. Even with careful capsular repair, the literature confirms an increased risk of postoperative instability, dislocation and stiffness[ 2 ]. The MAASH technique (MT)[ 3 ], introduced as a modification of the Hardinge direct lateral approach, was developed to preserve key anterior capsular ligaments—specifically the lateral iliofemoral (LIFL) and pubofemoral ligaments (PFL)—while maintaining a clear operative field through a selective capsulotomy and capsulectomy called the MAASH window (MW) corresponding to the internervous safe zone[ 4 ] (Fig. 1 ). This technique avoids extended capsulotomies, offers anatomic restoration of balance, and eliminates the need for MW closure to prevent stiffness. This study focused specifically on the evaluation of postoperative hip dislocation rate and mean net leg length discrepancy (netLLD) after THR surgery performing MT approach. METHODS This study is a retrospective observational case series (Level IV evidence) that evaluates the outcomes of total hip replacements (THRs) performed using MT over a 15-year period, from January 2010 to January 2025. All procedures were conducted in a National Health Service hospital. Patients were selected for primary THR based on clinical indication after conservative treatments had been exhausted. Written informed consent was obtained from each patient, and the study was approved by the institutional ethics committee. All patient data were anonymized for analysis. Surgeons trained in the MAASH technique carried out all procedures. Exclusion criteria included femoral neck fractures, high-grade hip dysplasia and prior hip surgery. To ensure comprehensive outcome tracking, the Clinical Health Shared Record[5] (HC3) of XXXXXXX, was consulted for each case. This secure electronic platform facilitates access to patient data across regional public health centers, enabling the identification of any complications or reoperations, even if managed outside the index hospital. Brief description of the MAASH technique The MAASH technique is a modification of the anterolateral approach described by Hardinge[6] in decubitus lateralis for THR. Vastus lateralis , and gluteus medius fibers are kept intact while gluteus minimus is elevated, tagged with a suture, and repaired when closing the wound, reattached to its native footprint (fig. 2). Placing two bent Hohmann elevators, one superior capsule and one inferior to the capsule, MT surgeons only excise the middle third of the anterior hip capsule (fig. 1) and sacrificing a little portion of the medial iliofemoral ligament in the so called “internervous safe zone”[4], the MAASH Window is created. When MW is excised, it provides an excellent view for the surgeon, preserving completely two main ligament structures of the anterior hip capsule, the lateral iliofemoral and the pubofemoral ligaments. No extended capsulotomy is needed, obtaining excellent acetabular and femoral visualization (fig. 3). The acetabular and femoral implants are placed in the same fashion as in a standard anterolateral approach. As the preservation of the hip ligaments provides a high stability of the prosthesis’s components, we do not recommend to reduce the trial head into the acetabulum in order to measure the neck size, as dislocation of the components might prove difficult. Instead, the “equator rule test (ERT)” was described in Delgado et al’s first description of MT[3]: after the implantation of acetabular and femoral components, a medium-sized trial head is inserted and the limb is positioned in lateral decubitus position. If the equator of the trial head lies within the rim of the acetabular component, a medium-sized neck should be chosen. However, if the equator of the trial head lies proximally to the rim, a shorter size would be preferred, and if, on the other hand, it lies distally, a longer neck would be necessary (fig. 4). Finally, no closure of MW is performed in any way due to potential stiffness. Type of Implants Stems with extended offset, modular or customized devices were not used. Computer navigation or double mobility cups were not used either. During the fifteen year-period, fourteen different combinations of regular THR implant were used (table 2). Type of implants fixation, (table 3) and head size, neck length size and pair of friction were recorded. (tables 4a, 4b, 4c) Radiographic measurements Radiographic measurements were carried out using IMPAX® software (Agfa Healthcare, Mortsel, Belgium) for cup abduction angle and cup angle anteversion in pelvic plain x-ray (standing position), according to Widmer and Liaw specifications[7, 8]. Measurements were performed by two senior consultants (fig. 5). Radiographic measurements, including neck length and cup position, were reviewed using standardized imaging protocols. NetLLD was calculated from the difference between preoperative and postoperative LLD, both adjusted for an 8% X-ray magnification factor. Statistical analysis Data regarding net LLD, THR stability, THR implant positioning (cup abduction angle and anteversion) and complications were obtained. Statistical and clinical differences, between sex, age, etiology, previous coxa type (coxa vara, coxa valga or coxa norma) and surgical timing were found via statistical analysis using SPSS software (SPSS IBM® v15, Chicago, USA). This statistical analysis was carried out using ANOVA (one-way test), T-test and linear regression analysis when necessary, taking p < .05 as a reference value to establish statistical significance. As well, F-ratio value was also looked upon, as it is related to a clinical significance when it is above 5. No intra-observer bias was calculated neither statistical power was reported. Ethics, funding and potential conflicts of interest This study was approved by our local ethics committee (CEIC Local Ethics committee) under approval ID number CEI20212008. No funding sources are reported. None of the authors have conflict of interest. RESULTS A total of 1006 MT procedures were performed in our hospital during this period. The following cases were excluded: 280 femoral neck fractures (226 hemiarthroplasties and 54 THRs), due to the potential disruption of the capsular ligaments caused by the trauma. 10 Crowe III or IV hip dysplasia 6 cases, as excessive deformity could interfere with capsular balance. 12 cases with prior hip surgery. 16 cases lacking complete records or follow-up (move to another region or country) 17 patients who passed away during follow-up from causes unrelated to the hip surgery After exclusions, the final study population included 671 consecutive primary THRs performed using the MAASH technique. The etiologies included all stages of primary osteoarthritis in 524 cases, 101 cases of femoral head osteonecrosis, 5 cases of childhood disease of the hip (Perthes disease or epiphysiolysis), 13 cases of acetabular dysplasia, 6 rheumatic diseases and 22 coxa protrusio as other secondary causes of degenerative joint disease. There were 402 male patients (59.9%) with a mean age of 62.4 years (range, 22–89) and 269 female patients (40.1%) with a mean age of 66.1 years (range, 25–91), with a significant difference in age distribution between sexes (p = 0.01; F = 12.2). Coxa type was classified according to the cervico-diaphyseal angle: Coxa vara (angle 135°): 10.8% of cases Surgical Time The mean operative time was 85.9 minutes (SD, 20.0 minutes). Operations lasting longer than 100 minutes were associated with a significantly higher rate of complications (p < 0.0001; F = 2.309), particularly major complications (p = 0.001; F = 5.376) and increased perioperative hemoglobin loss (p < 0.0001; F = 22.69). Operative time was not influenced by patient sex (p = 0.797), age (p = 0.108), or coxa type. Postoperative Stability Throughout the follow-up period (mean 83.2 months; range, 14–180 months), no postoperative dislocations were observed. Leg Length Discrepancy The mean netLLD, was 4.8 mm (standard deviation [SD], 4.1 mm). A discrepancy of ≤10 mm was achieved in 89.9% of cases, and ≤6 mm in 78.3%. NetLLD was statistically associated with etiology (p = 0.035; F = 1.296) and age (p = 0.044; F = 1.297), but these differences were not considered clinically meaningful, regarding the low F value. No significant associations were observed between netLLD and sex (p = 0.597), preoperative coxa type (p = 0.286), or age analyzed as a continuous variable (p = 0.293). Acetabular component orientation was also evaluated: The mean acetabular abduction angle was 44.4° ± 20°, and the mean cup anteversion was 9.6° ± 8°. Anteversion was significantly greater in female patients (p < 0.0001; F = 19.18), whereas no sex-related differences were observed in abduction angles (p = 0.959). Age had a statistically significant effect on abduction angle (p = 0.003; F = 1.689). Etiology and preoperative coxa type did not significantly influence cup position. Complications A total of 25 complications were recorded, yielding a complication rate of 3.7%. 10 periprosthetic fractures (1.5%) occurred intraoperatively, three of which required stem revision. Nine periprosthetic joint infections (1.3%) —three acute and six chronic (more than one year after the procedure)— necessitated component revision in all cases. Four cases of aseptic loosening and two cases of suspected iliopsoas impingement were noted, with cup positioning at 38° and 49° of abduction and 8° of anteversion, all of them were revised. In summary, 18 cases were revised, 9 aseptic loosening and 9 for septic condition. (table 1) There was no statistically significant association between overall complication rate and etiology (p = 0.548), sex (p = 0.746), or age (p = 0.798). However, male patients experienced significantly greater perioperative hemoglobin loss (p = 0.002; F = 9.592). DISCUSSION This 15-year observational study evaluating 671 consecutive primary THRs using the MAASH technique confirms the long-term safety and biomechanical validity of this capsular-preserving approach. The complete absence of dislocations across the cohort and a net leg length discrepancy (netLLD) averaging just 4.8 mm (SD 4.1) reflect the reliability of preserving anterior capsular integrity in achieving both joint stability and accurate biomechanical restoration[ 3 ]. The MAASH technique, a refinement of the Hardinge[ 6 ] approach, preserves the lateral iliofemoral and pubofemoral ligaments while creating a limited anterior capsulotomy through a defined internervous “MAASH Window”. These preserved capsular structures serve as critical stabilizers, especially in terminal hip motion, contributing substantial passive resistance to dislocation[ 9 , 10 ]. Their preservation may explain the technique’s superior stability, even in high-risk patients. Numerous biomechanical studies support the role of these ligaments in resisting edge loading and rotational forces post-THA[ 11 – 13 ]. Indeed, experimental modeling suggests that their contribution to joint stability is comparable to or even exceeds that of optimized component positioning[ 1 ]. Our findings align with Lu et al. (2019)[ 14 ], who showed that preserving the capsule in anterolateral approaches significantly reduces dislocation rates, and with Sheth et al. (2015)[ 15 ], who demonstrated that anterior-based approaches yield lower dislocation risk without increasing revision rates. While the Lewinnek’s safe zone has long served as a radiographic benchmark for cup positioning, multiple studies now challenge its predictive value for dislocation[ 16 , 17 ]. In our series, cup abduction (mean 44.4°) and anteversion (mean 9.6°) fell within the safe parameters; however, the zero-dislocation rate achieved suggests that capsular preservation may exert a more dominant stabilizing influence than component orientation alone. Our netLLD of 4.8 mm compares favorably to reported averages of 6–10 mm in conventional THA[ 18 , 19 ], where discrepancies beyond 6 mm have been associated with altered gait, dissatisfaction, and increased medico-legal claims[ 20 , 21 ]. The MT relies on intraoperative tensioning rather than preoperative templating or computer navigation may offer a reproducible strategy to limit length discrepancy, especially when combined with the ERT for trial reduction sizing (Fig. 4 ). Our complication rate of 3.7%, including early and chronic infections, minor fractures, and mechanical loosening (Table 1 ), is notably lower than that reported in national registries and anterior approaches with longer learning curves[ 22 , 23 ]. Importantly, no cases of prosthetic instability or dislocation occurred, despite the absence of dual mobility or constrained implants. In Sweden, a study analyzing data from the Swedish Hip Arthroplasty Register found that the true dislocation incidence following elective THR was higher than previously reported[ 24 ]. Despite being one of the largest single-center evaluations of a capsular-sparing THA technique, the study’s observational design and the lack of a randomized control group constrain its external validity. In conclusion, the MAASH technique offers a reliable and biomechanically grounded approach to total hip arthroplasty that simultaneously addresses two major sources of patient dissatisfaction: prosthetic instability and leg length discrepancy. Across 671 consecutive cases and 15 years of follow-up, this technique yielded a zero-dislocation rate and mean netLLD of just 4.8 mm—outcomes that compare favorably with both registry data and published literature. By preserving the key anterior ligamentous structures of the hip capsule and utilizing intraoperative tension assessment rather than templating or navigation, the MAASH technique demonstrates that stability and length control can be achieved through respect for native anatomy rather than dependence on mechanical augmentations or complex instrumentation. These findings support broader clinical adoption of the MAASH approach, particularly in patients at increased risk of dislocation or with complex anatomy. CONCLUSIONS Over a 15-year period and 671 consecutive primary total hip replacements, the MAASH technique achieved a zero-dislocation rate and consistently controlled leg length discrepancy, with 89.9% of patients within 10 mm and 78.3% within 6 mm of equality. By preserving key anterior capsular ligaments, this approach provides durable stability and accurate biomechanical restoration without the need for constrained or dual mobility implants. The MAASH technique offers a safe, reproducible option for surgeons seeking to minimize instability and leg length discrepancy in total hip arthroplasty. Declarations Ethics approval and consent to participate This study was approved by the local institutional ethics committee (CEIC Local Ethics Committee) under approval ID number CEI20212008. Written informed consent was obtained from all participants prior to inclusion. All procedures were conducted in accordance with the Declaration of Helsinki and relevant local regulations. Consent for publication Written informed consent for publication of anonymized clinical data and images was obtained from all participants. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Patient-level data are not publicly available to protect confidentiality. Competing interests The authors declare that they have no competing interests. Funding The authors received no specific funding for this work. Authors’ contributions FR and FD participated in the description of the surgical technique. AB and EN measured radiological outcomes. DT and AS performed the literature revision. AB, EN and AS participated in the redaction of the manuscript. All the authors reviewed the text. References van Arkel RJ, Jeffers JRT. In vitro hip testing in the International Society of Biomechanics coordinate system. J Biomech 2016; 49: 4154–4158. Stahelin T, Drittenbass L, Hersche O, et al. Failure of capsular enhanced short external rotator repair after total hip replacement. Clin Orthop Relat Res 2004; 199–204. Delgado FG, Broch A, Reina F, et al. MAASH Technique for Total Hip Arthroplasty: A Capsular Work. HSS J 2013; 9: 171–179. Kampa RJ, Prasthofer a, Lawrence-Watt DJ, et al. The internervous safe zone for incision of the capsule of the hip. A cadaver study. J Bone Joint Surg Br 2007; 89: 971–976. TicSalutSocial. Electronic Health Shared Record (HC3), https://ticsalutsocial.cat/en/projectes/interoperability/hc3/ (2013). Kevin Hardinge. Surgical Approach to the Hip: Direct Lateral. J bone Jt Surg Br 1982; 64: 17–19. Widmer KH. A simplified method to determine acetabular cup anteversion from plain radiographs. J Arthroplasty 2004; 19: 387–390. Liaw C, Hou S-M, Yang R-S, et al. New Tool for Measuring Cup Orientation i total hip arthroplasties from plain radiographs. Curr Orthop Relat Res 2006; 134–139. van Arkel RJ, Amis AA, Jeffers JRT. The envelope of passive motion allowed by the capsular ligaments of the hip. J Biomech 2015; 48: 3803–3809. Stewart KJ, Edmonds-Wilson RH, Brand RA, et al. Spatial distribution of hip capsule structural and material properties. J Biomech 2002; 35: 1491–1498. Nam D, Sculco PK, Abdel MP, et al. Leg-length inequalities following THA based on surgical technique. Orthopedics 2013; 36: e395-400. Tsutsumi M, Nimura A, Akita K. New insight into the iliofemoral ligament based on the anatomical study of the hip joint capsule. J Anat . Epub ahead of print 2019. DOI: 10.1111/joa.13140. Elkins JM, Stroud NJ, Rudert MJ, et al. The capsule’s contribution to total hip construct stability-A finite element analysis. J Orthop Res 2011; 29: 1642–1648. Lu Y, Wu Z, Tang X, et al. Effect of articular capsule repair on postoperative dislocation after primary total hip replacement by the anterolateral approach. J Int Med Res 2019; 47: 4787–4797. Sheth D, Cafri G, Inacio MCS, et al. Anterior and Anterolateral Approaches for THA Are Associated With Lower Dislocation Risk Without Higher Revision Risk. Clin Orthop Relat Res 2015; 473: 3401–3408. Abdel MP, von Roth P, Jennings MT, et al. What Safe Zone? The Vast Majority of Dislocated THAs Are Within the Lewinnek Safe Zone for Acetabular Component Position. Clin Orthop Relat Res 2016; 474: 386–391. Tezuka T, Heckmann ND, Bodner RJ, et al. Functional Safe Zone Is Superior to the Lewinnek Safe Zone for Total Hip Arthroplasty: Why the Lewinnek Safe Zone Is Not Always Predictive of Stability. J Arthroplasty ; 34. Epub ahead of print 2019. DOI: 10.1016/j.arth.2018.10.034. Pathak PK, Gupta RK, Meena HS, et al. Limb length discrepancy after total hip arthroplasty : a systematic review. 2018; 4: 690–697. Clark CR, Huddleston HD, Schoch EP, et al. Leg-length discrepancy after total hip arthroplasty. J Am Acad Orthop Surg 2006; 14: 38–45. Beard DJ, Palan J, Andrew JG, et al. Incidence and effect of leg length discrepancy following total hip arthroplasty. Physiotherapy 2008; 94: 91–96. Konyves a, Bannister GC. The importance of leg length discrepancy after total hip arthroplasty. J Bone Joint Surg Br 2005; 87: 155–157. Spaans AJ, Van Den Hout JAAM, Bolder SBT. High complication rate in the early experience of minimally invasive total hip arthroplasty by the direct anterior approach. Acta Orthop 2012; 83: 342–346. Tay K, Tang A, Fary C, et al. The effect of surgical approach on early complications of total hip arthoplasty. Arthroplasty 2019; 1: 1–7. Cnudde PHJ, Nåtman J, Rolfson O. The True Dislocation Incidence following Elective Total Hip Replacement in Sweden : How Does It Relate to the Revision Rate ? J Clin Med 2024, 13(2), 598; Epub ahead of print 2024. DOI: https://doi.org/10.3390/jcm13020598. Tables Tables 1 to 4 are available in the Supplementary Files section Additional Declarations No competing interests reported. Supplementary Files Tables.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 18 Sep, 2025 Reviewers invited by journal 17 Sep, 2025 Editor invited by journal 29 Aug, 2025 Editor assigned by journal 27 Aug, 2025 Submission checks completed at journal 27 Aug, 2025 First submitted to journal 11 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. 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. 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11:45:21","extension":"html","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":84202,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7100131/v1/5ef5139409e8e6955ae9e7d1.html"},{"id":92257171,"identity":"08fa67b8-4a38-4e54-9e0f-d9917fa2b583","added_by":"auto","created_at":"2025-09-26 11:45:21","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":429566,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7100131/v1/83c8393b302933a766b4d25b.png"},{"id":92257531,"identity":"8cf69d34-3b19-430c-b111-8a7913ab42fb","added_by":"auto","created_at":"2025-09-26 11:53:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":288159,"visible":true,"origin":"","legend":"\u003cp\u003eDecubitus lateralis. C-shape tenotomy of the gluteus minimus (***) while leaving intact the vastus lateralis (**) and the gluteus medius (*)\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7100131/v1/c05746f2a1380047b604f422.png"},{"id":92257180,"identity":"ef18d205-e30b-4f8f-979a-afafc0b62979","added_by":"auto","created_at":"2025-09-26 11:45:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":375466,"visible":true,"origin":"","legend":"\u003cp\u003eLeft, acetabular cup from distal to proximal in lateral decubitus. Right, a detail of the femoral canal reamed and ready to insert the stem.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7100131/v1/3162bac285c5146329853114.png"},{"id":92257175,"identity":"31335eb7-38c9-4eb9-b80e-8cb63cd7c16d","added_by":"auto","created_at":"2025-09-26 11:45:21","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":235137,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentation of the “equator rule test (ERT)”, described by Delgado et al. on the first report of MT: after the implantation of acetabular and femoral components, a medium-sized trial head is inserted and the limb is positioned in lateral decubitus position. If the equator of the trial head lies within the rim of the acetabular component, a medium-sized neck should be chosen. However, if the equator of the trial head lies proximally to the rim, a shorter size would be preferred, and if, on the other hand, it lies distally, a longer neck would be necessary\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7100131/v1/d4325e69d7ab16b4dcdb8048.png"},{"id":92257173,"identity":"903bf9ec-f334-46ca-8cf0-36249ca86c05","added_by":"auto","created_at":"2025-09-26 11:45:21","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":205951,"visible":true,"origin":"","legend":"\u003cp\u003eLeft. An angle of cup anteversion is obtained, using the short axis of a projected ellipse and the total length of the projected cup cross-section. In this case is 8 degree of cup anteversion\u003c/p\u003e\n\u003cp\u003eRight. Regarding netLLD, the net value was calculated, being the difference between the pre-operative and post-operative values of LLD, measured with the intertrochanteric line measuring the distance of the tear drop method, in a standing plain x-ray.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7100131/v1/59d0db6adea0f0d6b666e1ab.png"},{"id":92257804,"identity":"34e4f441-d58c-456d-83f5-492fe193abfc","added_by":"auto","created_at":"2025-09-26 11:53:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2373390,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7100131/v1/5f74f40e-2bbf-4809-8f8a-4d4b64791293.pdf"},{"id":92257169,"identity":"ec410673-52f4-4e77-8a8d-8ac3a46747ff","added_by":"auto","created_at":"2025-09-26 11:45:21","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":18564,"visible":true,"origin":"","legend":"","description":"","filename":"Tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-7100131/v1/365cea4b4102c6a164814326.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"The MAASH Technique in Total Hip Arthroplasty: A 15-Year Retrospective Study of 671 Cases without Dislocation and controlled leg length discrepancy","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eLeg length discrepancy (LLD) and dislocation following total hip replacement (THR) remain two of the most challenging and widely discussed complications in orthopedic surgery worldwide, with significant impact on patient satisfaction and healthcare burden. Hip capsular ligaments provide essential passive stabilization, particularly at the limits of hip motion, preventing edge loading and contributing to joint security across the full range of motion[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eNumerous surgical approaches have been developed for primary THR, but most of them involve partial or complete release of the hip joint capsule, thereby weakening its stabilizing function. Even with careful capsular repair, the literature confirms an increased risk of postoperative instability, dislocation and stiffness[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe MAASH technique (MT)[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], introduced as a modification of the Hardinge direct lateral approach, was developed to preserve key anterior capsular ligaments\u0026mdash;specifically the lateral iliofemoral (LIFL) and pubofemoral ligaments (PFL)\u0026mdash;while maintaining a clear operative field through a selective capsulotomy and capsulectomy called the MAASH window (MW) corresponding to the internervous safe zone[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). This technique avoids extended capsulotomies, offers anatomic restoration of balance, and eliminates the need for MW closure to prevent stiffness.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThis study focused specifically on the evaluation of postoperative hip dislocation rate and mean net leg length discrepancy (netLLD) after THR surgery performing MT approach.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cp\u003eThis study is a retrospective observational case series (Level IV evidence) that evaluates the outcomes of total hip replacements (THRs) performed using MT over a 15-year period, from January 2010 to January 2025. All procedures were conducted in a National Health Service hospital. Patients were selected for primary THR based on clinical indication after conservative treatments had been exhausted. Written informed consent was obtained from each patient, and the study was approved by the institutional ethics committee. All patient data were anonymized for analysis. Surgeons trained in the MAASH technique carried out all procedures.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eExclusion criteria included femoral neck fractures, high-grade hip dysplasia and prior hip surgery.\u003c/p\u003e\n\u003cp\u003eTo ensure comprehensive outcome tracking, the Clinical Health Shared Record[5] (HC3) of XXXXXXX, was consulted for each case. This secure electronic platform facilitates access to patient data across regional public health centers, enabling the identification of any complications or reoperations, even if managed outside the index hospital.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eBrief description of the MAASH technique\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe MAASH technique is a modification of the anterolateral approach described by Hardinge[6] in \u003cem\u003edecubitus lateralis\u003c/em\u003e for THR. \u003cem\u003eVastus lateralis\u003c/em\u003e, and \u003cem\u003egluteus medius\u003c/em\u003e fibers are kept intact while \u003cem\u003egluteus minimus\u003c/em\u003e is elevated, tagged with a suture, and repaired when closing the wound, reattached to its native footprint (fig. 2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePlacing two bent Hohmann elevators, one superior capsule and one inferior to the capsule, MT surgeons only excise the middle third of the anterior hip capsule (fig. 1) and sacrificing a little portion of the medial iliofemoral ligament in the so called “internervous safe zone”[4], the MAASH Window is created. When MW is excised, it provides an excellent view for the surgeon, preserving completely two main ligament structures of the anterior hip capsule, the lateral iliofemoral and the pubofemoral ligaments. No extended capsulotomy is needed, obtaining excellent acetabular and femoral visualization (fig. 3).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe acetabular and femoral implants are placed in the same fashion as in a standard anterolateral approach. As the preservation of the hip ligaments provides a high stability of the prosthesis’s components, we do not recommend to reduce the trial head into the acetabulum in order to measure the neck size, as dislocation of the components might prove difficult. Instead, the “equator rule test (ERT)” was described in Delgado et al’s first description of MT[3]: after the implantation of acetabular and femoral components, a medium-sized trial head is inserted and the limb is positioned in lateral decubitus position. If the equator of the trial head lies within the rim of the acetabular component, a medium-sized neck should be chosen. However, if the equator of the trial head lies proximally to the rim, a shorter size would be preferred, and if, on the other hand, it lies distally, a longer neck would be necessary (fig. 4).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFinally, no closure of MW is performed in any way due to potential stiffness.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eType of Implants \u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eStems with extended offset, modular or customized devices were not used. Computer navigation or double mobility cups were not used either. During the fifteen year-period, fourteen different combinations of regular THR implant were used (table 2). Type of implants fixation, (table 3) and head size, neck length size and pair of friction were recorded. (tables 4a, 4b, 4c) \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eRadiographic measurements \u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eRadiographic measurements were carried out using IMPAX® software (Agfa Healthcare, Mortsel, Belgium) for cup abduction angle and cup angle anteversion in pelvic plain x-ray (standing position), according to Widmer and Liaw specifications[7, 8]. \u0026nbsp;Measurements were performed by two senior consultants (fig. \u0026nbsp;5).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRadiographic measurements, including neck length and cup position, were reviewed using standardized imaging protocols. NetLLD was calculated from the difference between preoperative and postoperative LLD, both adjusted for an 8% X-ray magnification factor.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eStatistical analysis \u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eData regarding net LLD, THR stability, THR implant positioning (cup abduction angle and anteversion) and complications were obtained. Statistical and clinical differences, between sex, age, etiology, previous coxa type (coxa vara, coxa valga or coxa norma) and surgical timing were found via statistical analysis using SPSS software (SPSS IBM® v15, Chicago, USA).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis statistical analysis was carried out using ANOVA (one-way test), T-test and linear regression analysis when necessary, taking p \u0026lt; .05 as a reference value to establish statistical significance. As well, F-ratio value was also looked upon, as it is related to a clinical significance when it is above 5.\u0026nbsp;No intra-observer bias was calculated neither statistical power was reported.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEthics, funding and potential conflicts of interest \u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by our local ethics committee (CEIC Local Ethics committee) under approval ID number CEI20212008. No funding sources are reported. None of the authors have conflict of interest. \u0026nbsp;\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eA total of 1006 MT procedures were performed in our hospital during this period. The following cases were excluded:\u0026nbsp;\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e280 femoral neck fractures (226 hemiarthroplasties and 54 THRs), due to the potential disruption of the capsular ligaments caused by the trauma.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e10 Crowe III or IV hip dysplasia\u003csup\u003e6\u003c/sup\u003e cases, as excessive deformity could interfere with capsular balance.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e12 cases with prior hip surgery.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e16 cases lacking complete records or follow-up (move to another region or country)\u003c/li\u003e\n \u003cli\u003e17 patients who passed away during follow-up from causes unrelated to the hip surgery\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eAfter exclusions, the final study population included 671 consecutive primary THRs performed using the MAASH technique.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe etiologies included all stages of primary osteoarthritis in 524 cases, 101 cases of femoral head osteonecrosis, 5 cases of childhood disease of the hip (Perthes disease or epiphysiolysis), 13 cases of acetabular dysplasia, 6 rheumatic diseases and 22 coxa protrusio as other secondary causes of degenerative joint disease. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThere were 402 male patients (59.9%) with a mean age of 62.4 years (range, 22–89) and 269 female patients (40.1%) with a mean age of 66.1 years (range, 25–91), with a significant difference in age distribution between sexes (p = 0.01; F = 12.2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCoxa type\u003c/em\u003e was classified according to the cervico-diaphyseal angle:\u0026nbsp;\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eCoxa vara (angle \u0026lt;125°): 18.8% of cases\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eCoxa norma (125–135°): 70.4% of cases\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eCoxa valga (\u0026gt;135°): 10.8% of cases\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cem\u003eSurgical Time\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe mean operative time was 85.9 minutes (SD, 20.0 minutes). Operations lasting longer than 100 minutes were associated with a significantly higher rate of complications (p \u0026lt; 0.0001; F = 2.309), particularly major complications (p = 0.001; F = 5.376) and increased perioperative hemoglobin loss (p \u0026lt; 0.0001; F = 22.69). Operative time was not influenced by patient sex (p = 0.797), age (p = 0.108), or coxa type.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003ePostoperative Stability\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThroughout the follow-up period (mean 83.2 months; range, 14–180 months), no postoperative dislocations were observed.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eLeg Length\u0026nbsp;Discrepancy\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe mean netLLD, was 4.8 mm (standard deviation [SD], 4.1 mm).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA discrepancy of ≤10 mm was achieved in 89.9% of cases, and ≤6 mm in 78.3%. NetLLD was statistically associated with etiology (p = 0.035; F = 1.296) and age (p = 0.044; F = 1.297), but these differences were not considered clinically meaningful, regarding the low F value. No significant associations were observed between netLLD and sex (p = 0.597), preoperative coxa type (p = 0.286), or age analyzed as a continuous variable (p = 0.293).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAcetabular component orientation\u003c/em\u003e was also evaluated:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe mean acetabular abduction angle was 44.4° ± 20°, and the mean cup anteversion was 9.6° ± 8°.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAnteversion was significantly greater in female patients (p \u0026lt; 0.0001; F = 19.18), whereas no sex-related differences were observed in abduction angles (p = 0.959). Age had a statistically significant effect on abduction angle (p = 0.003; F = 1.689). Etiology and preoperative coxa type did not significantly influence cup position.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eComplications\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eA total of 25 complications were recorded, yielding a complication rate of 3.7%. 10 periprosthetic fractures (1.5%) occurred intraoperatively, three of which required stem revision. Nine periprosthetic joint infections (1.3%) —three acute and six chronic (more than one year after the procedure)— necessitated component revision in all cases. Four cases of aseptic loosening and two cases of suspected iliopsoas impingement were noted, with cup positioning at 38° and 49° of abduction and 8° of anteversion, all of them were revised. In summary, 18 cases were revised, 9 aseptic loosening and 9 for septic condition. (table 1) \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThere was no statistically significant association between overall complication rate and etiology (p = 0.548), sex (p = 0.746), or age (p = 0.798). However, male patients experienced significantly greater perioperative hemoglobin loss (p = 0.002; F = 9.592).\u0026nbsp;\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis 15-year observational study evaluating 671 consecutive primary THRs using the MAASH technique confirms the long-term safety and biomechanical validity of this capsular-preserving approach. The complete absence of dislocations across the cohort and a net leg length discrepancy (netLLD) averaging just 4.8 mm (SD 4.1) reflect the reliability of preserving anterior capsular integrity in achieving both joint stability and accurate biomechanical restoration[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe MAASH technique, a refinement of the Hardinge[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] approach, preserves the lateral iliofemoral and pubofemoral ligaments while creating a limited anterior capsulotomy through a defined internervous \u0026ldquo;MAASH Window\u0026rdquo;. These preserved capsular structures serve as critical stabilizers, especially in terminal hip motion, contributing substantial passive resistance to dislocation[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Their preservation may explain the technique\u0026rsquo;s superior stability, even in high-risk patients.\u003c/p\u003e\u003cp\u003eNumerous biomechanical studies support the role of these ligaments in resisting edge loading and rotational forces post-THA[\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Indeed, experimental modeling suggests that their contribution to joint stability is comparable to or even exceeds that of optimized component positioning[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Our findings align with Lu et al. (2019)[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], who showed that preserving the capsule in anterolateral approaches significantly reduces dislocation rates, and with Sheth et al. (2015)[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], who demonstrated that anterior-based approaches yield lower dislocation risk without increasing revision rates.\u003c/p\u003e\u003cp\u003eWhile the Lewinnek\u0026rsquo;s safe zone has long served as a radiographic benchmark for cup positioning, multiple studies now challenge its predictive value for dislocation[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. In our series, cup abduction (mean 44.4\u0026deg;) and anteversion (mean 9.6\u0026deg;) fell within the safe parameters; however, the zero-dislocation rate achieved suggests that capsular preservation may exert a more dominant stabilizing influence than component orientation alone.\u003c/p\u003e\u003cp\u003eOur netLLD of 4.8 mm compares favorably to reported averages of 6\u0026ndash;10 mm in conventional THA[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], where discrepancies beyond 6 mm have been associated with altered gait, dissatisfaction, and increased medico-legal claims[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. The MT relies on intraoperative tensioning rather than preoperative templating or computer navigation may offer a reproducible strategy to limit length discrepancy, especially when combined with the ERT for trial reduction sizing (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eOur complication rate of 3.7%, including early and chronic infections, minor fractures, and mechanical loosening (Table \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e1\u003c/span\u003e), is notably lower than that reported in national registries and anterior approaches with longer learning curves[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Importantly, no cases of prosthetic instability or dislocation occurred, despite the absence of dual mobility or constrained implants. In Sweden, a study analyzing data from the Swedish Hip Arthroplasty Register found that the true dislocation incidence following elective THR was higher than previously reported[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eDespite being one of the largest single-center evaluations of a capsular-sparing THA technique, the study\u0026rsquo;s observational design and the lack of a randomized control group constrain its external validity.\u003c/p\u003e\u003cp\u003eIn conclusion, the MAASH technique offers a reliable and biomechanically grounded approach to total hip arthroplasty that simultaneously addresses two major sources of patient dissatisfaction: prosthetic instability and leg length discrepancy. Across 671 consecutive cases and 15 years of follow-up, this technique yielded a zero-dislocation rate and mean netLLD of just 4.8 mm\u0026mdash;outcomes that compare favorably with both registry data and published literature.\u003c/p\u003e\u003cp\u003eBy preserving the key anterior ligamentous structures of the hip capsule and utilizing intraoperative tension assessment rather than templating or navigation, the MAASH technique demonstrates that stability and length control can be achieved through respect for native anatomy rather than dependence on mechanical augmentations or complex instrumentation. These findings support broader clinical adoption of the MAASH approach, particularly in patients at increased risk of dislocation or with complex anatomy.\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eOver a 15-year period and 671 consecutive primary total hip replacements, the MAASH technique achieved a zero-dislocation rate and consistently controlled leg length discrepancy, with 89.9% of patients within 10 mm and 78.3% within 6 mm of equality. By preserving key anterior capsular ligaments, this approach provides durable stability and accurate biomechanical restoration without the need for constrained or dual mobility implants. The MAASH technique offers a safe, reproducible option for surgeons seeking to minimize instability and leg length discrepancy in total hip arthroplasty.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cem\u003eEthics approval and consent to participate\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the local institutional ethics committee (CEIC Local Ethics Committee) under approval ID number CEI20212008. Written informed consent was obtained from all participants prior to inclusion. All procedures were conducted in accordance with the Declaration of Helsinki and relevant local regulations.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConsent for publication\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent for publication of anonymized clinical data and images was obtained from all participants.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAvailability of data and materials\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Patient-level data are not publicly available to protect confidentiality.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCompeting interests\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors received no specific funding for this work.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAuthors’ contributions\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eFR and FD participated in the description of the surgical technique.\u003c/p\u003e\n\u003cp\u003eAB and EN measured radiological outcomes.\u003c/p\u003e\n\u003cp\u003eDT and AS performed the literature revision.\u003c/p\u003e\n\u003cp\u003eAB, EN and AS participated in the redaction of the manuscript.\u003c/p\u003e\n\u003cp\u003eAll the authors reviewed the text.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003evan Arkel RJ, Jeffers JRT. In vitro hip testing in the International Society of Biomechanics coordinate system. \u003cem\u003eJ Biomech\u003c/em\u003e 2016; 49: 4154\u0026ndash;4158.\u003c/li\u003e\n \u003cli\u003eStahelin T, Drittenbass L, Hersche O, et al. Failure of capsular enhanced short external rotator repair after total hip replacement. \u003cem\u003eClin Orthop Relat Res\u003c/em\u003e 2004; 199\u0026ndash;204.\u003c/li\u003e\n \u003cli\u003eDelgado FG, Broch A, Reina F, et al. MAASH Technique for Total Hip Arthroplasty: A Capsular Work. \u003cem\u003eHSS J\u003c/em\u003e 2013; 9: 171\u0026ndash;179.\u003c/li\u003e\n \u003cli\u003eKampa RJ, Prasthofer a, Lawrence-Watt DJ, et al. The internervous safe zone for incision of the capsule of the hip. A cadaver study. \u003cem\u003eJ Bone Joint Surg Br\u003c/em\u003e 2007; 89: 971\u0026ndash;976.\u003c/li\u003e\n \u003cli\u003eTicSalutSocial. Electronic Health Shared Record (HC3), https://ticsalutsocial.cat/en/projectes/interoperability/hc3/ (2013).\u003c/li\u003e\n \u003cli\u003eKevin Hardinge. Surgical Approach to the Hip: Direct Lateral. \u003cem\u003eJ bone Jt Surg Br\u003c/em\u003e 1982; 64: 17\u0026ndash;19.\u003c/li\u003e\n \u003cli\u003eWidmer KH. A simplified method to determine acetabular cup anteversion from plain radiographs. \u003cem\u003eJ Arthroplasty\u003c/em\u003e 2004; 19: 387\u0026ndash;390.\u003c/li\u003e\n \u003cli\u003eLiaw C, Hou S-M, Yang R-S, et al. New Tool for Measuring Cup Orientation i total hip arthroplasties from plain radiographs. \u003cem\u003eCurr Orthop Relat Res\u003c/em\u003e 2006; 134\u0026ndash;139.\u003c/li\u003e\n \u003cli\u003evan Arkel RJ, Amis AA, Jeffers JRT. The envelope of passive motion allowed by the capsular ligaments of the hip. \u003cem\u003eJ Biomech\u003c/em\u003e 2015; 48: 3803\u0026ndash;3809.\u003c/li\u003e\n \u003cli\u003eStewart KJ, Edmonds-Wilson RH, Brand RA, et al. Spatial distribution of hip capsule structural and material properties. \u003cem\u003eJ Biomech\u003c/em\u003e 2002; 35: 1491\u0026ndash;1498.\u003c/li\u003e\n \u003cli\u003eNam D, Sculco PK, Abdel MP, et al. Leg-length inequalities following THA based on surgical technique. \u003cem\u003eOrthopedics\u003c/em\u003e 2013; 36: e395-400.\u003c/li\u003e\n \u003cli\u003eTsutsumi M, Nimura A, Akita K. New insight into the iliofemoral ligament based on the anatomical study of the hip joint capsule. \u003cem\u003eJ Anat\u003c/em\u003e. Epub ahead of print 2019. DOI: 10.1111/joa.13140.\u003c/li\u003e\n \u003cli\u003eElkins JM, Stroud NJ, Rudert MJ, et al. The capsule\u0026rsquo;s contribution to total hip construct stability-A finite element analysis. \u003cem\u003eJ Orthop Res\u003c/em\u003e 2011; 29: 1642\u0026ndash;1648.\u003c/li\u003e\n \u003cli\u003eLu Y, Wu Z, Tang X, et al. Effect of articular capsule repair on postoperative dislocation after primary total hip replacement by the anterolateral approach. \u003cem\u003eJ Int Med Res\u003c/em\u003e 2019; 47: 4787\u0026ndash;4797.\u003c/li\u003e\n \u003cli\u003eSheth D, Cafri G, Inacio MCS, et al. Anterior and Anterolateral Approaches for THA Are Associated With Lower Dislocation Risk Without Higher Revision Risk. \u003cem\u003eClin Orthop Relat Res\u003c/em\u003e 2015; 473: 3401\u0026ndash;3408.\u003c/li\u003e\n \u003cli\u003eAbdel MP, von Roth P, Jennings MT, et al. What Safe Zone? The Vast Majority of Dislocated THAs Are Within the Lewinnek Safe Zone for Acetabular Component Position. \u003cem\u003eClin Orthop Relat Res\u003c/em\u003e 2016; 474: 386\u0026ndash;391.\u003c/li\u003e\n \u003cli\u003eTezuka T, Heckmann ND, Bodner RJ, et al. Functional Safe Zone Is Superior to the Lewinnek Safe Zone for Total Hip Arthroplasty: Why the Lewinnek Safe Zone Is Not Always Predictive of Stability. \u003cem\u003eJ Arthroplasty\u003c/em\u003e; 34. Epub ahead of print 2019. DOI: 10.1016/j.arth.2018.10.034.\u003c/li\u003e\n \u003cli\u003ePathak PK, Gupta RK, Meena HS, et al. Limb length discrepancy after total hip arthroplasty : a systematic review. 2018; 4: 690\u0026ndash;697.\u003c/li\u003e\n \u003cli\u003eClark CR, Huddleston HD, Schoch EP, et al. Leg-length discrepancy after total hip arthroplasty. \u003cem\u003eJ Am Acad Orthop Surg\u003c/em\u003e 2006; 14: 38\u0026ndash;45.\u003c/li\u003e\n \u003cli\u003eBeard DJ, Palan J, Andrew JG, et al. Incidence and effect of leg length discrepancy following total hip arthroplasty. \u003cem\u003ePhysiotherapy\u003c/em\u003e 2008; 94: 91\u0026ndash;96.\u003c/li\u003e\n \u003cli\u003eKonyves a, Bannister GC. The importance of leg length discrepancy after total hip arthroplasty. \u003cem\u003eJ Bone Joint Surg Br\u003c/em\u003e 2005; 87: 155\u0026ndash;157.\u003c/li\u003e\n \u003cli\u003eSpaans AJ, Van Den Hout JAAM, Bolder SBT. High complication rate in the early experience of minimally invasive total hip arthroplasty by the direct anterior approach. \u003cem\u003eActa Orthop\u003c/em\u003e 2012; 83: 342\u0026ndash;346.\u003c/li\u003e\n \u003cli\u003eTay K, Tang A, Fary C, et al. The effect of surgical approach on early complications of total hip arthoplasty. \u003cem\u003eArthroplasty\u003c/em\u003e 2019; 1: 1\u0026ndash;7.\u003c/li\u003e\n \u003cli\u003eCnudde PHJ, N\u0026aring;tman J, Rolfson O. The True Dislocation Incidence following Elective Total Hip Replacement in Sweden : How Does It Relate to the Revision Rate ? \u003cem\u003eJ Clin Med 2024, 13(2), 598;\u003c/em\u003e Epub ahead of print 2024. DOI: https://doi.org/10.3390/jcm13020598.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 4 are available in the Supplementary Files section\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Hip, stability, prostheses, MAASH, leg length discrepancy","lastPublishedDoi":"10.21203/rs.3.rs-7100131/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7100131/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground \u003c/strong\u003e\u003cbr\u003e\nDislocation and leg length discrepancy (LLD) are persistent challenges in Total Hip Replacement (THR), contributing to patient dissatisfaction and increased revision rates. The MAASH technique, a modification of the Hardinge direct lateral approach, preserves anterior capsular ligaments through a selective capsulotomy known as the MAASH Window. This study evaluates the long-term outcomes of the MAASH technique over a 15-year period.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003cbr\u003e\nA retrospective observational study included 671 consecutive primary THRs performed using the MAASH technique between 2010 and 2025. Radiographic analysis comprised acetabular component positioning and leg length measurements. Net leg length discrepancy (netLLD) was defined as the postoperative minus preoperative LLD, adjusted for radiographic magnification. Statistical analysis was performed using ANOVA, t-tests, and regression, with significance set at p \u0026lt; 0.05.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003cbr\u003e\nNo dislocations were reported during the 15-year span of this study. The mean netLLD was 4.8 mm (SD 4.1), with discrepancies ≤10 mm in 89.9% of cases and ≤6 mm in 78.3%. Acetabular component positioning fell within conventional safe zone parameters. A total of 25 complications (3.7%) were recorded, including periprosthetic fractures (1.5%), infections (1.3%), and aseptic loosening (0.6%). Longer surgical time (\u0026gt;100 minutes) was significantly associated with higher complication rates (p\u0026lt;0.0001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003cbr\u003e\nThe MAASH technique provides reliable stability and leg length control in primary THR, with zero dislocations and reduced leg length discrepancy in comparison with previous studies. Capsular preservation may play a key role in enhancing biomechanical outcomes without the need for constrained or dual mobility implants.\u003c/p\u003e","manuscriptTitle":"The MAASH Technique in Total Hip Arthroplasty: A 15-Year Retrospective Study of 671 Cases without Dislocation and controlled leg length discrepancy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-26 11:45:16","doi":"10.21203/rs.3.rs-7100131/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"84510467498129867999813875643990247042","date":"2025-09-18T07:07:36+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-17T13:51:07+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-08-29T15:12:53+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-27T10:13:30+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-27T10:12:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2025-07-11T09:26:26+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"81dfa3da-b5d6-4027-9b7d-f29cf5338b4f","owner":[],"postedDate":"September 26th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-09-26T11:45:16+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-26 11:45:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7100131","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7100131","identity":"rs-7100131","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}