Modified trochanteric flip osteotomy in varus intertrochanteric osteotomy for treatment of Legg-Calvé-Perthes disease

Modified trochanteric flip osteotomy in varus intertrochanteric osteotomy for treatment of Legg-Calvé-Perthes disease | 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 Modified trochanteric flip osteotomy in varus intertrochanteric osteotomy for treatment of Legg-Calvé-Perthes disease Andrea Laufer, Carina Antfang, Georg Gosheger, Adrien Frommer, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4635415/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Legg-Calvé-Perthes disease (LCPD) presents challenges in treatment due to its varied course and unclear etiology. This study aimed to evaluate the efficacy of combining proximal femoral varus osteotomy (PFVO) with a modified trochanteric flip osteotomy to address biomechanical consequences and improve hip abductor muscle strength. Methods We present a modified approach combining PFVO with a trochanteric flip osteotomy. In this technique the greater trochanter in compound with its muscular insertions is separated from the femur and attached distally using a varization blade plate. Eight patients (nine hips) with LCPD were treated using this technique. Clinical examination findings and radiographic evaluations were retrospectively analyzed. The median follow-up was 28 months. Results At the last follow-up, two patients exhibited Trendelenburg gait, but hip abduction was improved in all patients. Radiographically, consolidation at the osteotomy site was observed in all cases, with no delayed union or non-union. The mean CE angle improved by 7.6°, while the mean CCD decreased by 19.5°. The mean MPFA decreased by 17.5° resulting in a mean of 81°. Conclusion Combining PFVO with a modified trochanteric flip osteotomy addresses biomechanical issues associated with PFVO, potentially improving hip containment and abductor muscle strength. This approach may offer advantages over traditional osteotomy techniques in treating LCPD. Despite satisfactory radiological outcomes in most cases, further research is needed to assess long-term effectiveness and address challenges such as femoral head enlargement and persistent gait abnormalities. Legg-Calvé-Perthes disease trochanteric flip osteotomy varus intertrochanteric osteotomy release cut blade plate Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Background Legg-Calvé-Perthes disease (LCPD) is an idiopathic osteonecrosis of the developing hip caused by interruption of blood supply to the femoral head [ 1 ]. The avascular osteo- or chondronecrosis of the capital femoral epiphysis can cause severe deformity of the proximal femur and may ultimately lead to secondary osteoarthritis [ 2 ]. The aetiology of the disease still remains mostly unclear [ 1 , 3 ]. It appears that mechanical as well as biological and environmental factors contribute to the development and may also be responsible for the heterogeneous epidemiologic and clinical features of this condition [ 1 , 2 , 4 ]. The varying and often unpredictable course of the disorder causes controversies upon the most adequate treatment regimen. Severe courses frequently lead to progressive deformation of the proximal femur resulting in early-onset osteoarthritis, irrespective of the chosen treatment regimen [ 2 , 5 ]. On the other hand, intermediate courses of LCPD, presenting head-at-risk signs, do appear to benefit from surgery [ 6 ]. The main aim of treatment is preserving hip containment to retain the femoral head within the acetabulum during the period of regeneration of the capital femoral epiphysis, as well as preservation of the blood supply of the femoral head to maintain the spherical shape and prevent progressive deformation [ 6 , 7 ]. Restoration of containment may either be achieved through pelvic or proximal femoral varus osteotomy (PFVO). Triple pelvic osteotomy is widely performed and has been reported to produce satisfactory results in regard of hip containment [ 8 ]. However, it should be noted that pelvic osteotomies bear a greater perioperative risk compared to PFVO [ 9 ]. Furthermore, LCPD is primarily a condition affecting the proximal femur, and should preferably be addressed at the origin of the deformity. However, traditional PFVO has been associated with significant biomechanical impairments, and it has been criticized that containment treatment by PFVO disregards potential long-term sequelae [ 10 ]. Apart from producing leg length discrepancies through femoral shortening, the greater trochanter is inevitably proximalized, resulting in an overriding greater trochanter and, consecutively, insufficiency of the hip abductor muscles which frequently leads to Trendelenburg gait [ 11 , 12 ]. Moreover, an overriding greater trochanter may contribute to increased pressure to the femoral head, which may result in further chondral damage [ 13 ]. However, the aforementioned biomechanical consequences of an overriding greater trochanter may be alleviated by greater trochanteric transfer to restore abductor muscle strength, resulting in improved gait [ 14 – 16 ]. We thus combined PFVO with a distalization of the greater trochanter through a modified trochanteric flip osteotomy [ 17 ]. The greater trochanter in conjunction with the hip abductor muscles and the vastus lateralis is reattached in a distalized, adequate anatomical position in relation to the femoral head. We hypothesize that this technique may decrease the risk of developing Trendelenburg gait by maintaining hip abductor muscle strength. Methods Patients Since 2018, eight patients (nine hips) (seven males, two females) were treated with a modified trochanteric flip osteotomy combined with varus intertrochanteric osteotomy. A chart review was performed to retrospectively evaluate clinical examination findings and clinical course. Median follow-up was 28 months (6–63), with one patient lost to follow-up after the first postoperative control. Surgical treatment was considered in all children with LCPD who either presented a deterioration of the condition clinically (increasing pain, restricted range of motion, limping), or if a radiological tendency towards a more severe course of deformity with head-at-risk signs and Herring group B, B/C or C were observed. All children had a dynamic arthrography before the surgical intervention to detect a potential hinge abduction phenomenon (Fig. 1 ). If hinge abduction was detected, surgical treatment was not conducted. Surgical technique and Follow-Up Protocol All procedures were performed by two senior surgeons (RR, BV), who are also authors of this study. A standard lateral approach to the proximal femur was performed and the fascia lata was split to visualize the posterior aspect of the greater trochanter (Fig. 2 a). The latter was than separated from the proximal femur in compound with the attachment of the gluteus medius and vastus lateralis muscles through a vertical osteotomy with an oscillating saw (Fig. 2 b, c) before it was distalized under abduction of the hip. Excessive medial penetration of the proximal femur with the saw and osteotome, respectively, were avoided to prevent the risk of injury to the medial femoral circumflex artery. Furthermore, to protect the soft tissues including the medial circumflex artery subperiosteal retractors were placed circumferentially around the osteotomy site. Subsequently, a recess cut was carried out for medialization of the distal fragment, as the offset of the blade plate was completely filled by the distalized greater trochanter (Fig. 3 ). A guide wire was then introduced into the femoral neck approaching from the distalized greater trochanter under consideration of the preoperatively determined correction angle. After radiographical verification of the correct wire position, the seating chisel and chisel guide were inserted over the guide wire, and the seating chisel was impacted to the appropriate depth (Fig. 4 a). After removal of the chisel guide, the osteotomy was performed at the proximal femur to achieve the predetermined angular correction, after which the blade plate (90° or 100°; OrthoPediatrics, IN, USA; Fig. 4 b, c) was inserted over the guide wire. Thus, the blade threaded through the distalized greater trochanter and fixated it to the femoral neck while fixating the plate to the bone in a varus position by locking screws (Fig. 4 d). Postoperatively, weight-bearing was completely restricted for six weeks. Physiotherapy was initiated during the hospital stay and was recommended at least once per week in the outpatient setting. Follow-up appointments were scheduled six weeks postoperatively, and in three-month intervals from then. Preoperative and Postoperative Clinical and Radiographic Evaluation Anteroposterior and axial radiographs of the hip were analysed preoperatively and at the last follow-up. The radiological evaluation was performed with regards to stage of disease according to Waldenstroem, joint orientation and axis alignment, with reference to established parameters [ 18 ]. The lateral pillar was assessed according to the Herring classification. For the children who reached the final stage of LCPD the evaluation of the sphericity of femoral head was performed taking the Stulberg classification into consideration. Concerning joint orientation, the medial proximal femoral angle (MPFA), the centre-edge (CE) angle and the caput-collum-diaphyseal (CCD) angle were evaluated. The position of the tip of the greater trochanter in regard to the centre of the femoral head was determined measuring the articulo-trochanteric distance (Fig. 5 a) as well as the centre head-trochanteric distance (Fig. 5 b). Results Clinical and Radiographic Results The mean age at surgery was 7.8 years (range, 5–11). At the time of surgery, radiographs showed initial stage in one hip, condensation stage in four hips, and fragmentation stages in four hips. Herring group B was determined in one case, group B/C in four cases, and group C in four cases. Catteral class II was observed in one case, class III in one case, and class IV in seven cases. Limping was present in four patients. Hip abduction was limited to 10 degrees or less in two patients. At the time of the last follow-up, two of seven patients presented Trendelenburg gait. Hip abduction was 20 degrees or more in all patients. Limb length discrepancy of more than 10 mm was observed in three patients. Radiographically, all patients presented sufficient consolidation at the osteotomy site. There were no cases of delayed union or non-union, nor implant failure. Two hips presented Stulberg group II and one hip Stulberg group V. Three hips were still in the fragmentation phase, and two in the reparative phase according to Waldenstroem. The median MPFA was 100.5° preoperatively and 81° postoperatively, with a median decrease of 17.5° (range, 3° to 29°). The median CE angle was 16.5° preoperatively and 23° postoperatively, with a median improvement of 7.6° (range, 0° to 20°). The CE angle improved in 6/8 hips, while it did not change in two hips. The median CCD was 142° preoperatively, and 117° postoperatively, with a median decrease of the CCD of 19.5° (range, 11° to 41°). The articulo-trochanteric distance increased in four patients and decreased in four patients, respectively. The median articulo-trochanteric distance was 18.0 mm preoperatively (range, 14.5 mm to 24 mm) and 17.2 mm postoperatively (range, 5.8 mm to 29 mm). The median centre head-trochanteric distance was 6.0 mm preoperatively and 8.5 mm postoperatively, with a median increase of 2.0 mm (range, -4 mm to 6 mm). At the time of the last follow up, implants had been removed in five of eight hips. The mean time between initial surgery and implant retrieval was 19.8 months (range, 10–45). Discussion Since its introduction in 1965 [ 19 ], PFVO has become an established surgical treatment approach for LCPD [ 20 ]. By producing increased varus angulation of the proximal femur, the femoral head is centred within the acetabulum [ 21 ]. To further improve containment the proximal femur may additionally be altered in the sagittal and transverse plane through modifications of the osteotomy [ 22 ]. The aim is to shift the fragile capital femoral epiphysis out of the main load zone [ 22 ]. The load-relieving effect may ultimately improve remodelling of the biologically plastic femoral head during the healing or revascularization phase [ 21 , 22 ]. Moreover, relocation of the femoral head through PFVO does not influence the acetabular centre of rotation, as is the case in pelvic osteotomies. Thus, an increase of the intraarticular pressure and further impairment of the blood supply to the femoral head can be avoided [ 23 ]. PFVO has shown to achieve radiographic results – in particular regarding the Stulberg classification – superior to those of patients undergoing non-operative treatment [ 20 ]. Nonetheless, correct indication and timing of PFVO are crucial to achieve a satisfactory outcome. Containment should be re-established before onset of re-ossification of the femoral head [ 24 ]. If conducted in a timely manner, PFVO may help to shorten the fragmentation phase, and femoral head deformation may be less severe due to the reduced lateral subluxation of the femoral head [ 5 , 24 ]. Ideally, the spherical shape of the femoral head can be preserved. In particular patients older than six years of age should be considered for surgical treatment, as the ability of the femoral head to spontaneously remodel seems to remarkably decrease beyond this age [ 25 ]. This patient group also appears to benefit more from PFVO than non-operative treatment [ 5 , 21 ]. Even though PFVO has been reported to be beneficial to the healing process if indication, timing and technique are executed appropriately, it is also associated with certain pitfalls and disadvantages. For instance, preservation of the medial femoral circumflex artery is of utmost significance to maintain sufficient blood supply to the proximal femur and prevent further damage [ 10 ]. Furthermore, overcorrection of varus angulation may shift part of the femoral neck into the main load zone, resulting in incorrect load distribution which may impair healing of the capital femoral epiphysis in a spherical shape [ 22 ]. It is generally recommended to not produce a varus angulation of less than 100° [ 26 , 27 ]. However, even moderate varization of the proximal femur will inevitably produce an elevation of the tip of the greater trochanter relative to the centre of rotation of the femoral head. An overriding greater trochanter, in turn, results in shortening of the origin to insertion length and a reduced lever arm of the hip abductor muscles [ 28 ]. The decreased resting length and abductor lever arm ratio may lead to a functional insufficiency of the hip abductors [ 29 ]. Owed to this, Trendelenburg gait as well as fatigue pain on walking are frequently observed after PFVO and may persist permanently [ 30 ]. Moreover, an overriding greater trochanter may also cause painful pelvitrochanteric impingement, further limiting hip joint mobility [ 31 ]. Combining PFVO with a modified trochanteric flip osteotomy to distalize the greater trochanter addresses these issues by reestablishing the original resting length and lever arm, thus maintaining hip abductor strength. The necessity of subsequent surgeries may hence be avoided by preserving or improving hip function, pain, and gait. The principle and rationale of the PFVO with trochanter distalization for treatment of LCPD was first presented by Birke et al. at the EPOS meeting 2016 [ 32 ]. Birke combined a trochanter flip approach and development of the retinacular soft tissue flap with a novel release cut technique to achieve varization with the necessary medialisation of the femoral shaft. He utilized a 130 degree cannulated blade plate allowing sufficient bone stock for refixation of the distalised greater trochanter, which was fixated at the lateral aspect of the plate. We modified this technique by employing a 90 or 100 degree rather than a 130 degree blade plate, which allows threading the greater trochanter with the blade and fixating it to the femoral neck. However, since the threaded greater trochanter impedes sufficient medialization through the blade offset, a recess cut is still required to avoid lateral translation of the distal fragment. Even though radiologically, adequate distalization of the greater trochanter was observed after PFVO with a modified trochanter flip osteotomy, we nevertheless observed persistent Trendelenburg gait in two patients. This may be ought to the fact that we performed only moderate lateralization of the greater trochanter. However, apart from height of the greater trochanter, an adequate distance between the centre of the femoral head and the tip of the greater trochanter also plays an important role regarding the effectiveness of abductor muscle strength, since the pelvitrochanteric muscles require less force to maintain the pelvis level during the single stance phase [ 33 ]. In LCPD, enlargement of the femoral head is frequently observed, thus reducing the centre head-trochanteric distance. This may lead to weakening of hip abductor muscle strength, even if the greater trochanter has been sufficiently distalized [ 29 ]. In patients preoperatively presenting an enlarged femoral head and Trendelenburg gait, more aggressive lateralization of the greater trochanter should thus be considered to improve hip abductor strength. Alternatively, a femoral neck lengthening osteotomy has been declared effective to achieve this goal, while concomitantly decreasing leg length discrepancy [ 29 ]. However, it should be noted that femoral neck lengthening osteotomy inevitably increases the intraarticular pressure and may thus aggravate deformation of the femoral head in LCPD. Apophyseodesis of the greater trochanter has been proposed as another alternative approach to PFVO to prevent an overriding greater trochanter and, consecutively, Trendelenburg gait [ 10 ]. This procedure may also avoid iatrogenic varus deformity [ 34 ]. However, it has been constituted that this measure only renders effective if performed before eight years of age and if Trendelenburg gait has not yet established [ 35 , 36 ]. Apart of age at surgery, it appears that the size of the femoral head at healing significantly influences the effectiveness of apophyseodesis of the greater trochanter [ 37 ], thus further limiting its applicability. We thus believe that in patients in whom this technique is not applicable, PFVO combined with a modified trochanter flip osteotomy is an efficient procedure to restore the physiological position of the greater trochanter and hence improve hip containment, while showing an improved biomechanical outcome compared to traditional osteotomy techniques. Even though we observed an unsatisfactory radiological outcome with Stulberg Class V hip in one patient patients of the studied cohort at the time of last follow-up, it should be noted that this patient showed Herring class C preoperatively, which reportedly is associated with a poorer treatment outcome, irrespective of age at and choice of treatment [ 21 ]. Moreover, the pathogenesis of LCPD is immensely complex and it may thus not always be sufficient to solely modify biomechanical factors [ 5 ]. Conclusion Despite satisfactory radiological outcomes in most cases, further research is needed to assess long-term effectiveness and address challenges such as femoral head enlargement and persistent gait abnormalities. This modified technique offers a promise in preserving hip function and preventing complications associated with traditional PFVO. Abbreviations LCPD Legg-Calvé-Perthes disease PFVO proximal femoral varus osteotomy CE angle centre-edge angle CCD angle caput-collum diaphyseal angle = femoral neck-shaft angle MPFA medial proximal femoral angle Declarations Ethics approval and Consent to participate This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of the University of Muenster, Germany (registration number: 2023-432-f-S). Written informed consent was obtained from the parents or legal guardians, and all children included in the study gave their verbal assent. This study was retrospectively registered. Consent for publication A written informed consent was obtained from both patients and their families for publication of this report and any accompanying images. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Competing interests All authors state to not have any potential conflicts of interest. Funding Open Access funding enabled and organized by Project DEAL. This study was fully financed by the research funds of the University Hospital of Muenster, Germany Authors' contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Andrea Laufer, Carina Antfang and Bjoern Vogt. The first draft of the manuscript was written by Andrea Laufer and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgements We would like to thank Oliver Birke for his input and support in the development of the technique and the paper writing process. References Kim HK (2011) Legg-Calve-Perthes disease: etiology, pathogenesis, and biology. J Pediatr Orthop 31:S141-146. 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J Pediatr Orthop 29:889-895. DOI 10.1097/BPO.0b013e3181c1e943 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4635415","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":327775383,"identity":"0ab547d5-e84b-44d8-93a3-8be5ed710ec3","order_by":0,"name":"Andrea Laufer","email":"data:image/png;base64,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","orcid":"","institution":"University Hospital of Muenster","correspondingAuthor":true,"prefix":"","firstName":"Andrea","middleName":"","lastName":"Laufer","suffix":""},{"id":327775386,"identity":"19acd1ab-3463-499a-b017-200da16228b7","order_by":1,"name":"Carina Antfang","email":"","orcid":"","institution":"University Hospital of Muenster","correspondingAuthor":false,"prefix":"","firstName":"Carina","middleName":"","lastName":"Antfang","suffix":""},{"id":327775388,"identity":"e1cbb71b-f9f9-4ca6-bee9-29104e503c07","order_by":2,"name":"Georg Gosheger","email":"","orcid":"","institution":"University Hospital of Muenster","correspondingAuthor":false,"prefix":"","firstName":"Georg","middleName":"","lastName":"Gosheger","suffix":""},{"id":327775389,"identity":"58d00bee-461a-40f3-9547-ec09a4edd414","order_by":3,"name":"Adrien Frommer","email":"","orcid":"","institution":"University Hospital of Muenster","correspondingAuthor":false,"prefix":"","firstName":"Adrien","middleName":"","lastName":"Frommer","suffix":""},{"id":327775391,"identity":"7971241e-8fab-4ad5-a5ff-9d5d95bef396","order_by":4,"name":"Gregor Toporowski","email":"","orcid":"","institution":"University Hospital of Muenster","correspondingAuthor":false,"prefix":"","firstName":"Gregor","middleName":"","lastName":"Toporowski","suffix":""},{"id":327775392,"identity":"a8954b3b-7ca6-40f1-a2e2-2c750e9606d0","order_by":5,"name":"Henning Tretow","email":"","orcid":"","institution":"University Hospital of Muenster","correspondingAuthor":false,"prefix":"","firstName":"Henning","middleName":"","lastName":"Tretow","suffix":""},{"id":327775395,"identity":"107d1538-e6ad-4b67-a721-c62b7bdc0d13","order_by":6,"name":"Robert Roedl","email":"","orcid":"","institution":"University Hospital of Muenster","correspondingAuthor":false,"prefix":"","firstName":"Robert","middleName":"","lastName":"Roedl","suffix":""},{"id":327775396,"identity":"d908608a-0577-4845-830d-eb8acf5ae88e","order_by":7,"name":"Bjoern Vogt","email":"","orcid":"","institution":"University Hospital of Muenster","correspondingAuthor":false,"prefix":"","firstName":"Bjoern","middleName":"","lastName":"Vogt","suffix":""}],"badges":[],"createdAt":"2024-06-25 09:50:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4635415/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4635415/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":60633449,"identity":"3ca212f7-1fba-4bfe-959d-9e4fdbc2b36e","added_by":"auto","created_at":"2024-07-19 01:39:43","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":54675,"visible":true,"origin":"","legend":"\u003cp\u003eDynamic arthrography of the hip was performed in all patients preoperatively to rule out a hinge abduction phenomenon\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4635415/v1/4658f22b3d4a702702ecaabb.jpg"},{"id":60631887,"identity":"63b569d0-d0da-4db8-9675-26375fe88b39","added_by":"auto","created_at":"2024-07-19 01:23:43","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":106976,"visible":true,"origin":"","legend":"\u003cp\u003eLateral approach to the proximal femur with a fascia lata split (a) and vertical osteotomy at the base of the greater trochanter (b, c)\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4635415/v1/17f0b135c75c014c1276f86d.jpg"},{"id":60632413,"identity":"8956af12-9931-42a8-a3cd-2e7263210401","added_by":"auto","created_at":"2024-07-19 01:31:43","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":97264,"visible":true,"origin":"","legend":"\u003cp\u003eRecess cut at the proximal femur to achieve sufficient medialization of the distal fragment\u003c/p\u003e","description":"","filename":"Fig3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4635415/v1/b5504c7e267f3b2c4afa982f.jpg"},{"id":60631883,"identity":"59e41528-86ee-42f5-85ed-ab27cf8ab1ee","added_by":"auto","created_at":"2024-07-19 01:23:43","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":57488,"visible":true,"origin":"","legend":"\u003cp\u003eAfter preparation of the implant site with a cannulated chisel (a), a cannulated 90°- or 100° blade plate is inserted over a guide wire (b, c), threading the distalized greater trochanter and fixating it to the femoral neck (d)\u003c/p\u003e","description":"","filename":"Fig4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4635415/v1/a17e3c3cfe24508f0c080993.jpg"},{"id":60631885,"identity":"8a92233a-25be-4a03-adb7-5956c924bee7","added_by":"auto","created_at":"2024-07-19 01:23:43","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":155949,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of the articulo-trochanteric distance (a; red arrow) and the centre head-trochanteric distance (b; red arrow)\u003c/p\u003e","description":"","filename":"Fig5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4635415/v1/f2c86fea82af2a1ddf9cb20e.jpg"},{"id":61330129,"identity":"8d17fb0a-1512-4fae-bcd1-a88266f2c393","added_by":"auto","created_at":"2024-07-29 14:44:37","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":767945,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4635415/v1/819cb695-db95-4960-8328-9897c07d0504.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Modified trochanteric flip osteotomy in varus intertrochanteric osteotomy for treatment of Legg-Calvé-Perthes disease","fulltext":[{"header":"Background","content":"\u003cp\u003eLegg-Calvé-Perthes disease (LCPD) is an idiopathic osteonecrosis of the developing hip caused by interruption of blood supply to the femoral head [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The avascular osteo- or chondronecrosis of the capital femoral epiphysis can cause severe deformity of the proximal femur and may ultimately lead to secondary osteoarthritis [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The aetiology of the disease still remains mostly unclear [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. It appears that mechanical as well as biological and environmental factors contribute to the development and may also be responsible for the heterogeneous epidemiologic and clinical features of this condition [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The varying and often unpredictable course of the disorder causes controversies upon the most adequate treatment regimen. Severe courses frequently lead to progressive deformation of the proximal femur resulting in early-onset osteoarthritis, irrespective of the chosen treatment regimen [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. On the other hand, intermediate courses of LCPD, presenting head-at-risk signs, do appear to benefit from surgery [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The main aim of treatment is preserving hip containment to retain the femoral head within the acetabulum during the period of regeneration of the capital femoral epiphysis, as well as preservation of the blood supply of the femoral head to maintain the spherical shape and prevent progressive deformation [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Restoration of containment may either be achieved through pelvic or proximal femoral varus osteotomy (PFVO). Triple pelvic osteotomy is widely performed and has been reported to produce satisfactory results in regard of hip containment [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. However, it should be noted that pelvic osteotomies bear a greater perioperative risk compared to PFVO [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Furthermore, LCPD is primarily a condition affecting the proximal femur, and should preferably be addressed at the origin of the deformity. However, traditional PFVO has been associated with significant biomechanical impairments, and it has been criticized that containment treatment by PFVO disregards potential long-term sequelae [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Apart from producing leg length discrepancies through femoral shortening, the greater trochanter is inevitably proximalized, resulting in an overriding greater trochanter and, consecutively, insufficiency of the hip abductor muscles which frequently leads to Trendelenburg gait [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Moreover, an overriding greater trochanter may contribute to increased pressure to the femoral head, which may result in further chondral damage [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. However, the aforementioned biomechanical consequences of an overriding greater trochanter may be alleviated by greater trochanteric transfer to restore abductor muscle strength, resulting in improved gait [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e–\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. We thus combined PFVO with a distalization of the greater trochanter through a modified trochanteric flip osteotomy [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The greater trochanter in conjunction with the hip abductor muscles and the vastus lateralis is reattached in a distalized, adequate anatomical position in relation to the femoral head. We hypothesize that this technique may decrease the risk of developing Trendelenburg gait by maintaining hip abductor muscle strength.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003ePatients\u003c/p\u003e\u003cp\u003eSince 2018, eight patients (nine hips) (seven males, two females) were treated with a modified trochanteric flip osteotomy combined with varus intertrochanteric osteotomy. A chart review was performed to retrospectively evaluate clinical examination findings and clinical course. Median follow-up was 28 months (6–63), with one patient lost to follow-up after the first postoperative control.\u003c/p\u003e\u003cp\u003eSurgical treatment was considered in all children with LCPD who either presented a deterioration of the condition clinically (increasing pain, restricted range of motion, limping), or if a radiological tendency towards a more severe course of deformity with head-at-risk signs and Herring group B, B/C or C were observed. All children had a dynamic arthrography before the surgical intervention to detect a potential hinge abduction phenomenon (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). If hinge abduction was detected, surgical treatment was not conducted.\u003c/p\u003e\u003cp\u003eSurgical technique and Follow-Up Protocol\u003c/p\u003e\u003cp\u003eAll procedures were performed by two senior surgeons (RR, BV), who are also authors of this study.\u003c/p\u003e\u003cp\u003eA standard lateral approach to the proximal femur was performed and the fascia lata was split to visualize the posterior aspect of the greater trochanter (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). The latter was than separated from the proximal femur in compound with the attachment of the gluteus medius and vastus lateralis muscles through a vertical osteotomy with an oscillating saw (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb, c) before it was distalized under abduction of the hip. Excessive medial penetration of the proximal femur with the saw and osteotome, respectively, were avoided to prevent the risk of injury to the medial femoral circumflex artery.\u003c/p\u003e\u003cp\u003eFurthermore, to protect the soft tissues including the medial circumflex artery subperiosteal retractors were placed circumferentially around the osteotomy site. Subsequently, a recess cut was carried out for medialization of the distal fragment, as the offset of the blade plate was completely filled by the distalized greater trochanter (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eA guide wire was then introduced into the femoral neck approaching from the distalized greater trochanter under consideration of the preoperatively determined correction angle. After radiographical verification of the correct wire position, the seating chisel and chisel guide were inserted over the guide wire, and the seating chisel was impacted to the appropriate depth (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea). After removal of the chisel guide, the osteotomy was performed at the proximal femur to achieve the predetermined angular correction, after which the blade plate (90° or 100°; OrthoPediatrics, IN, USA; Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, c) was inserted over the guide wire. Thus, the blade threaded through the distalized greater trochanter and fixated it to the femoral neck while fixating the plate to the bone in a varus position by locking screws (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed).\u003c/p\u003e\u003cp\u003ePostoperatively, weight-bearing was completely restricted for six weeks. Physiotherapy was initiated during the hospital stay and was recommended at least once per week in the outpatient setting. Follow-up appointments were scheduled six weeks postoperatively, and in three-month intervals from then.\u003c/p\u003e\u003cp\u003ePreoperative and Postoperative Clinical and Radiographic Evaluation\u003c/p\u003e\u003cp\u003eAnteroposterior and axial radiographs of the hip were analysed preoperatively and at the last follow-up. The radiological evaluation was performed with regards to stage of disease according to Waldenstroem, joint orientation and axis alignment, with reference to established parameters [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. The lateral pillar was assessed according to the Herring classification. For the children who reached the final stage of LCPD the evaluation of the sphericity of femoral head was performed taking the Stulberg classification into consideration. Concerning joint orientation, the medial proximal femoral angle (MPFA), the centre-edge (CE) angle and the caput-collum-diaphyseal (CCD) angle were evaluated. The position of the tip of the greater trochanter in regard to the centre of the femoral head was determined measuring the articulo-trochanteric distance (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea) as well as the centre head-trochanteric distance (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eClinical and Radiographic Results\u003c/p\u003e \u003cp\u003eThe mean age at surgery was 7.8 years (range, 5\u0026ndash;11). At the time of surgery, radiographs showed initial stage in one hip, condensation stage in four hips, and fragmentation stages in four hips. Herring group B was determined in one case, group B/C in four cases, and group C in four cases. Catteral class II was observed in one case, class III in one case, and class IV in seven cases. Limping was present in four patients. Hip abduction was limited to 10 degrees or less in two patients.\u003c/p\u003e \u003cp\u003eAt the time of the last follow-up, two of seven patients presented Trendelenburg gait. Hip abduction was 20 degrees or more in all patients. Limb length discrepancy of more than 10 mm was observed in three patients. Radiographically, all patients presented sufficient consolidation at the osteotomy site. There were no cases of delayed union or non-union, nor implant failure. Two hips presented Stulberg group II and one hip Stulberg group V. Three hips were still in the fragmentation phase, and two in the reparative phase according to Waldenstroem.\u003c/p\u003e \u003cp\u003eThe median MPFA was 100.5\u0026deg; preoperatively and 81\u0026deg; postoperatively, with a median decrease of 17.5\u0026deg; (range, 3\u0026deg; to 29\u0026deg;). The median CE angle was 16.5\u0026deg; preoperatively and 23\u0026deg; postoperatively, with a median improvement of 7.6\u0026deg; (range, 0\u0026deg; to 20\u0026deg;). The CE angle improved in 6/8 hips, while it did not change in two hips. The median CCD was 142\u0026deg; preoperatively, and 117\u0026deg; postoperatively, with a median decrease of the CCD of 19.5\u0026deg; (range, 11\u0026deg; to 41\u0026deg;). The articulo-trochanteric distance increased in four patients and decreased in four patients, respectively. The median articulo-trochanteric distance was 18.0 mm preoperatively (range, 14.5 mm to 24 mm) and 17.2 mm postoperatively (range, 5.8 mm to 29 mm). The median centre head-trochanteric distance was 6.0 mm preoperatively and 8.5 mm postoperatively, with a median increase of 2.0 mm (range, -4 mm to 6 mm).\u003c/p\u003e \u003cp\u003eAt the time of the last follow up, implants had been removed in five of eight hips. The mean time between initial surgery and implant retrieval was 19.8 months (range, 10\u0026ndash;45).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eSince its introduction in 1965 [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], PFVO has become an established surgical treatment approach for LCPD [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. By producing increased varus angulation of the proximal femur, the femoral head is centred within the acetabulum [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. To further improve containment the proximal femur may additionally be altered in the sagittal and transverse plane through modifications of the osteotomy [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The aim is to shift the fragile capital femoral epiphysis out of the main load zone [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The load-relieving effect may ultimately improve remodelling of the biologically plastic femoral head during the healing or revascularization phase [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Moreover, relocation of the femoral head through PFVO does not influence the acetabular centre of rotation, as is the case in pelvic osteotomies. Thus, an increase of the intraarticular pressure and further impairment of the blood supply to the femoral head can be avoided [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePFVO has shown to achieve radiographic results \u0026ndash; in particular regarding the Stulberg classification \u0026ndash; superior to those of patients undergoing non-operative treatment [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Nonetheless, correct indication and timing of PFVO are crucial to achieve a satisfactory outcome. Containment should be re-established before onset of re-ossification of the femoral head [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. If conducted in a timely manner, PFVO may help to shorten the fragmentation phase, and femoral head deformation may be less severe due to the reduced lateral subluxation of the femoral head [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Ideally, the spherical shape of the femoral head can be preserved. In particular patients older than six years of age should be considered for surgical treatment, as the ability of the femoral head to spontaneously remodel seems to remarkably decrease beyond this age [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. This patient group also appears to benefit more from PFVO than non-operative treatment [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEven though PFVO has been reported to be beneficial to the healing process if indication, timing and technique are executed appropriately, it is also associated with certain pitfalls and disadvantages. For instance, preservation of the medial femoral circumflex artery is of utmost significance to maintain sufficient blood supply to the proximal femur and prevent further damage [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Furthermore, overcorrection of varus angulation may shift part of the femoral neck into the main load zone, resulting in incorrect load distribution which may impair healing of the capital femoral epiphysis in a spherical shape [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. It is generally recommended to not produce a varus angulation of less than 100\u0026deg; [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. However, even moderate varization of the proximal femur will inevitably produce an elevation of the tip of the greater trochanter relative to the centre of rotation of the femoral head. An overriding greater trochanter, in turn, results in shortening of the origin to insertion length and a reduced lever arm of the hip abductor muscles [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. The decreased resting length and abductor lever arm ratio may lead to a functional insufficiency of the hip abductors [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Owed to this, Trendelenburg gait as well as fatigue pain on walking are frequently observed after PFVO and may persist permanently [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Moreover, an overriding greater trochanter may also cause painful pelvitrochanteric impingement, further limiting hip joint mobility [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCombining PFVO with a modified trochanteric flip osteotomy to distalize the greater trochanter addresses these issues by reestablishing the original resting length and lever arm, thus maintaining hip abductor strength. The necessity of subsequent surgeries may hence be avoided by preserving or improving hip function, pain, and gait. The principle and rationale of the PFVO with trochanter distalization for treatment of LCPD was first presented by Birke et al. at the EPOS meeting 2016 [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Birke combined a trochanter flip approach and development of the retinacular soft tissue flap with a novel release cut technique to achieve varization with the necessary medialisation of the femoral shaft. He utilized a 130 degree cannulated blade plate allowing sufficient bone stock for refixation of the distalised greater trochanter, which was fixated at the lateral aspect of the plate. We modified this technique by employing a 90 or 100 degree rather than a 130 degree blade plate, which allows threading the greater trochanter with the blade and fixating it to the femoral neck. However, since the threaded greater trochanter impedes sufficient medialization through the blade offset, a recess cut is still required to avoid lateral translation of the distal fragment. Even though radiologically, adequate distalization of the greater trochanter was observed after PFVO with a modified trochanter flip osteotomy, we nevertheless observed persistent Trendelenburg gait in two patients. This may be ought to the fact that we performed only moderate lateralization of the greater trochanter. However, apart from height of the greater trochanter, an adequate distance between the centre of the femoral head and the tip of the greater trochanter also plays an important role regarding the effectiveness of abductor muscle strength, since the pelvitrochanteric muscles require less force to maintain the pelvis level during the single stance phase [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. In LCPD, enlargement of the femoral head is frequently observed, thus reducing the centre head-trochanteric distance. This may lead to weakening of hip abductor muscle strength, even if the greater trochanter has been sufficiently distalized [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. In patients preoperatively presenting an enlarged femoral head and Trendelenburg gait, more aggressive lateralization of the greater trochanter should thus be considered to improve hip abductor strength. Alternatively, a femoral neck lengthening osteotomy has been declared effective to achieve this goal, while concomitantly decreasing leg length discrepancy [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. However, it should be noted that femoral neck lengthening osteotomy inevitably increases the intraarticular pressure and may thus aggravate deformation of the femoral head in LCPD. Apophyseodesis of the greater trochanter has been proposed as another alternative approach to PFVO to prevent an overriding greater trochanter and, consecutively, Trendelenburg gait [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. This procedure may also avoid iatrogenic varus deformity [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. However, it has been constituted that this measure only renders effective if performed before eight years of age and if Trendelenburg gait has not yet established [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Apart of age at surgery, it appears that the size of the femoral head at healing significantly influences the effectiveness of apophyseodesis of the greater trochanter [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e], thus further limiting its applicability. We thus believe that in patients in whom this technique is not applicable, PFVO combined with a modified trochanter flip osteotomy is an efficient procedure to restore the physiological position of the greater trochanter and hence improve hip containment, while showing an improved biomechanical outcome compared to traditional osteotomy techniques. Even though we observed an unsatisfactory radiological outcome with Stulberg Class V hip in one patient patients of the studied cohort at the time of last follow-up, it should be noted that this patient showed Herring class C preoperatively, which reportedly is associated with a poorer treatment outcome, irrespective of age at and choice of treatment [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Moreover, the pathogenesis of LCPD is immensely complex and it may thus not always be sufficient to solely modify biomechanical factors [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eDespite satisfactory radiological outcomes in most cases, further research is needed to assess long-term effectiveness and address challenges such as femoral head enlargement and persistent gait abnormalities. This modified technique offers a promise in preserving hip function and preventing complications associated with traditional PFVO.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLCPD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLegg-Calv\u0026eacute;-Perthes disease\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePFVO\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eproximal femoral varus osteotomy\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCE angle\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ecentre-edge angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCCD angle\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ecaput-collum diaphyseal angle\u0026thinsp;=\u0026thinsp;femoral neck-shaft angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMPFA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003emedial proximal femoral angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003eEthics approval and Consent to participate\u003c/p\u003e\n\u003cp\u003eThis study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of the University of Muenster, Germany (registration number: 2023-432-f-S).\u0026nbsp;Written informed consent was obtained from the parents or legal guardians, and all children included in the study gave their verbal assent. This study was retrospectively registered.\u003c/p\u003e\n\u003cp\u003eConsent for publication\u003c/p\u003e\n\u003cp\u003eA written informed consent was obtained from both patients and their families for publication of this report\u0026nbsp;and any accompanying images.\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eCompeting interests\u003c/p\u003e\n\u003cp\u003eAll authors state to not have any potential conflicts of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eOpen Access funding enabled and organized by Project DEAL. This study was fully financed by the research funds of the University Hospital of Muenster, Germany\u003c/p\u003e\n\u003cp\u003eAuthors\u0026apos; contributions\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Andrea Laufer, Carina Antfang and Bjoern Vogt. The first draft of the manuscript was written by Andrea Laufer and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eWe would like to thank Oliver Birke for his input and support in the development of the technique and the paper writing process.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKim HK (2011) Legg-Calve-Perthes disease: etiology, pathogenesis, and biology. J Pediatr Orthop 31:S141-146. DOI 10.1097/BPO.0b013e318223b4bd\u003c/li\u003e\n\u003cli\u003eIbrahim T, Little DG (2016) The Pathogenesis and Treatment of Legg-Calve-Perthes Disease. JBJS Rev 4. DOI 10.2106/JBJS.RVW.15.00063\u003c/li\u003e\n\u003cli\u003eRodriguez-Olivas AO, Hernandez-Zamora E, Reyes-Maldonado E (2022) Legg-Calve-Perthes disease overview. Orphanet J Rare Dis 17:125. DOI 10.1186/s13023-022-02275-z\u003c/li\u003e\n\u003cli\u003ePerry DC, Hall AJ (2011) The epidemiology and etiology of Perthes disease. Orthop Clin North Am 42:279-283, v. DOI 10.1016/j.ocl.2011.03.002\u003c/li\u003e\n\u003cli\u003eHerring JA, Kim HT, Browne R (2004) Legg-Calve-Perthes disease. Part II: Prospective multicenter study of the effect of treatment on outcome. J Bone Joint Surg Am 86:2121-2134\u003c/li\u003e\n\u003cli\u003eStrobl WM (2020) Diagnostik und Therapie des Morbus Perthes. Monatsschrift Kinderheilkunde 168:363-375. DOI 10.1007/s00112-020-00872-5\u003c/li\u003e\n\u003cli\u003ePrice CT, Thompson GH, Wenger DR (2011) Containment methods for treatment of Legg-Calve-Perthes disease. Orthop Clin North Am 42:329-340, vi. DOI 10.1016/j.ocl.2011.04.008\u003c/li\u003e\n\u003cli\u003eWenger DR, Pring ME, Hosalkar HS, Caltoum CB, Lalonde FD, Bastrom TP (2010) Advanced containment methods for Legg-Calve-Perthes disease: results of triple pelvic osteotomy. J Pediatr Orthop 30:749-757. DOI 10.1097/BPO.0b013e3181f5a0de\u003c/li\u003e\n\u003cli\u003eZiebarth K, Kaiser N, Slongo T (2022) [Triple osteotomy for patients with Legg-Calve-Perthes disease]. Oper Orthop Traumatol 34:323-332. DOI 10.1007/s00064-022-00784-5\u003c/li\u003e\n\u003cli\u003eGrothaus O, Desperes M, Vanderhorst A, Wu C, Presson A, Stevens P (2022) Perthes disease: comparison of two surgical options. J Pediatr Orthop B. DOI 10.1097/BPB.0000000000001023\u003c/li\u003e\n\u003cli\u003eAksoy MC, Cankus MC, Alanay A, Yazici M, Caglar O, Alpaslan AM (2005) Radiological outcome of proximal femoral varus osteotomy for the treatment of lateral pillar group-C Legg-Calve-Perthes disease. J Pediatr Orthop B 14:88-91. DOI 10.1097/01202412-200503000-00005\u003c/li\u003e\n\u003cli\u003eWesthoff B, Lederer C, Krauspe R (2019) [Perthes disease-news in diagnostics and treatment]. Orthopade 48:515-522. DOI 10.1007/s00132-019-03737-2\u003c/li\u003e\n\u003cli\u003eMaquet PG (1985) Biomechanics of the Hip. In: Biomechanics of the Hip: As Applied to Osteoarthritis and Related Conditions. Springer. pp. 1-45.\u003c/li\u003e\n\u003cli\u003eEilert RE, Hill K, Bach J (2005) Greater trochanteric transfer for the treatment of coxa brevis. Clin Orthop Relat Res:92-101. DOI 10.1097/01.blo.0000163474.74168.6f\u003c/li\u003e\n\u003cli\u003eGarrido IM, Molto FJ, Lluch DB (2003) Distal transfer of the greater trochanter in acquired coxa vara. Clinical and radiographic results. J Pediatr Orthop B 12:38-43. DOI 10.1097/01.bpb.0000043729.21564.44\u003c/li\u003e\n\u003cli\u003eMacnicol MF, Makris D (1991) Distal transfer of the greater trochanter. J Bone Joint Surg Br 73:838-841. DOI 10.1302/0301-620X.73B5.1894678\u003c/li\u003e\n\u003cli\u003eGanz R, Gill TJ, Gautier E, Ganz K, Krugel N, Berlemann U (2001) Surgical dislocation of the adult hip a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg Br 83:1119-1124. DOI 10.1302/0301-620x.83b8.11964\u003c/li\u003e\n\u003cli\u003ePaley D (2002) Normal Lower Limb Alignment and Joint Orientation. In: Principles of Deformity Correction. Springer Berlin Heidelberg, Berlin, Heidelberg. pp. 1-18.\u003c/li\u003e\n\u003cli\u003eAxer A (1965) Subtrochanteric Osteotomy in the Treatment of Perthes\u0026apos; Disease: A Preliminary Report. J Bone Joint Surg Br 47:489-499\u003c/li\u003e\n\u003cli\u003eKim HK, da Cunha AM, Browne R, Kim HT, Herring JA (2011) How much varus is optimal with proximal femoral osteotomy to preserve the femoral head in Legg-Calve-Perthes disease? J Bone Joint Surg Am 93:341-347. DOI 10.2106/JBJS.J.00830\u003c/li\u003e\n\u003cli\u003eElzohairy MM (2016) Short follow-up evaluation of proximal femoral varus osteotomy for treatment of Legg-Calve-Perthes disease. J Orthop Traumatol 17:345-351. DOI 10.1007/s10195-016-0412-0\u003c/li\u003e\n\u003cli\u003eKr\u0026aacute;tk\u0026yacute; A, Kraus MJ, Krieg AH (2022) Proximale Varisationsosteotomie des Femurs beim Morbus Perthes. Operative Orthop\u0026auml;die und Traumatologie 34:307-322. DOI 10.1007/s00064-022-00778-3\u003c/li\u003e\n\u003cli\u003eSalter RB (1980) Legg-Perthes disease: the scientific basis for the methods of treatment and their indications. Clin Orthop Relat Res:8-11\u003c/li\u003e\n\u003cli\u003eJoseph B, Nair NS, Narasimha Rao K, Mulpuri K, Varghese G (2003) Optimal timing for containment surgery for Perthes disease. J Pediatr Orthop 23:601-606. DOI 10.1097/00004694-200309000-00006\u003c/li\u003e\n\u003cli\u003eWiig O, Terjesen T, Svenningsen S (2008) Prognostic factors and outcome of treatment in Perthes\u0026apos; disease: a prospective study of 368 patients with five-year follow-up. J Bone Joint Surg Br 90:1364-1371. DOI 10.1302/0301-620X.90B10.20649\u003c/li\u003e\n\u003cli\u003eHeikkinen E, Puranen J (1980) Evaluation of femoral osteotomy in the treatment of Legg-Calve-Perthes disease. Clin Orthop Relat Res:60-68\u003c/li\u003e\n\u003cli\u003eWeiner SD, Weiner DS, Riley PM (1991) Pitfalls in treatment of Legg-Calve-Perthes disease using proximal femoral varus osteotomy. J Pediatr Orthop 11:20-24. DOI 10.1097/01241398-199101000-00005\u003c/li\u003e\n\u003cli\u003eCooper RR (1977) Biomechanics of the Normal and Diseased Hip: Theoretical Foundation, Technique and Results of Treatment. JAMA 237:1623-1623. DOI 10.1001/jama.1977.03270420091031\u003c/li\u003e\n\u003cli\u003eJoo SY, Lee KS, Koh IH, Park HW, Kim HW (2008) Trochanteric Advancement in Patients with Legg-Calv\u0026eacute;-Perthes Disease Does Not Improve Pain or Limp. Clinical Orthopaedics and Related Research\u0026reg; 466:927-934. DOI 10.1007/s11999-008-0128-4\u003c/li\u003e\n\u003cli\u003eFollak N, Ganzer D, Merk H (2002) Einfluss der intertrochant\u0026auml;ren varisierenden Osteotomie beim Morbus Perthes auf das Gangbild von Kindern. Klin Padiatr 214:309-313. DOI 10.1055/s-2002-33982\u003c/li\u003e\n\u003cli\u003eBech NH, Haverkamp D (2018) Impingement around the hip: beyond cam and pincer. EFORT Open Rev 3:30-38. DOI 10.1302/2058-5241.3.160068\u003c/li\u003e\n\u003cli\u003eBirke O LD (2016) EPOS 35th Congress Meeting. J Child Orthop 10:91-137. DOI 10.1007/s11832-016-0714-z\u003c/li\u003e\n\u003cli\u003eKelikian AS, Tachdjian MO, Askew MJ, Jasty M (1983) Greater trochanteric advancement of the proximal femur: a clinical and biomechanical study. Hip:77-105\u003c/li\u003e\n\u003cli\u003eStevens PM, Anderson LA, Gililland JM, Novais E (2014) Guided growth of the trochanteric apophysis combined with soft tissue release for Legg-Calve-Perthes disease. Strategies Trauma Limb Reconstr 9:37-43. DOI 10.1007/s11751-014-0186-y\u003c/li\u003e\n\u003cli\u003eStevens PM, Coleman SS (1985) Coxa breva: its pathogenesis and a rationale for its management. J Pediatr Orthop 5:515-521\u003c/li\u003e\n\u003cli\u003eKwon KS, Wang SI, Lee JH, Moon YJ, Kim JR (2017) Effect of greater trochanteric epiphysiodesis after femoral varus osteotomy for lateral pillar classification B and B/C border Legg-Calve-Perthes disease: A retrospective observational study. Medicine (Baltimore) 96:e7723. DOI 10.1097/MD.0000000000007723\u003c/li\u003e\n\u003cli\u003eShah H, Siddesh ND, Joseph B, Nair SN (2009) Effect of prophylactic trochanteric epiphyseodesis in older children with Perthes\u0026apos; disease. J Pediatr Orthop 29:889-895. DOI 10.1097/BPO.0b013e3181c1e943\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Legg-Calvé-Perthes disease, trochanteric flip osteotomy, varus intertrochanteric osteotomy, release cut, blade plate","lastPublishedDoi":"10.21203/rs.3.rs-4635415/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4635415/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eLegg-Calv\u0026eacute;-Perthes disease (LCPD) presents challenges in treatment due to its varied course and unclear etiology. This study aimed to evaluate the efficacy of combining proximal femoral varus osteotomy (PFVO) with a modified trochanteric flip osteotomy to address biomechanical consequences and improve hip abductor muscle strength.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe present a modified approach combining PFVO with a trochanteric flip osteotomy. In this technique the greater trochanter in compound with its muscular insertions is separated from the femur and attached distally using a varization blade plate. Eight patients (nine hips) with LCPD were treated using this technique. Clinical examination findings and radiographic evaluations were retrospectively analyzed. The median follow-up was 28 months.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAt the last follow-up, two patients exhibited Trendelenburg gait, but hip abduction was improved in all patients. Radiographically, consolidation at the osteotomy site was observed in all cases, with no delayed union or non-union. The mean CE angle improved by 7.6\u0026deg;, while the mean CCD decreased by 19.5\u0026deg;. The mean MPFA decreased by 17.5\u0026deg; resulting in a mean of 81\u0026deg;.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eCombining PFVO with a modified trochanteric flip osteotomy addresses biomechanical issues associated with PFVO, potentially improving hip containment and abductor muscle strength. This approach may offer advantages over traditional osteotomy techniques in treating LCPD. Despite satisfactory radiological outcomes in most cases, further research is needed to assess long-term effectiveness and address challenges such as femoral head enlargement and persistent gait abnormalities.\u003c/p\u003e","manuscriptTitle":"Modified trochanteric flip osteotomy in varus intertrochanteric osteotomy for treatment of Legg-Calvé-Perthes disease","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-19 01:23:38","doi":"10.21203/rs.3.rs-4635415/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"675d3721-e7b7-4976-9355-a94dcc67583d","owner":[],"postedDate":"July 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-07-29T14:36:29+00:00","versionOfRecord":[],"versionCreatedAt":"2024-07-19 01:23:38","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4635415","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4635415","identity":"rs-4635415","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}