Expanding the Role of Tibial Tuberosity Osteotomy with Distalization and Medialization: Long- Term Success in Patellofemoral Instability Without Redislocations with a mean follow-up of 8.6 years – A Retrospective Case Series Study

Expanding the Role of Tibial Tuberosity Osteotomy with Distalization and Medialization: Long- Term Success in Patellofemoral Instability Without Redislocations with a mean follow-up of 8.6 years – A Retrospective Case Series Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Expanding the Role of Tibial Tuberosity Osteotomy with Distalization and Medialization: Long- Term Success in Patellofemoral Instability Without Redislocations with a mean follow-up of 8.6 years – A Retrospective Case Series Study Mikołaj Podsiadło, Wojciech Solecki, Paweł Pruś, Andrzej Solecki, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7862008/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 Patellofemoral instability is a multifactorial condition influenced by anatomical abnormalities and soft tissue dysfunction. Distalization of the tibial tuberosity is classically reserved for patients with patella alta, typically defined by a Caton–Deschamps (CD) index > 1.2. However, clinical experience suggests that certain patients with lower CD indices but distally deepening trochlear morphology may also benefit. This study is aimed to evaluate the long-term outcomes of tibial tuberosity osteotomy with distalization and medialization (TTO-DM) in patients with recurrent lateral patellar instability, regardless of patellar height. Materials and Methods This retrospective single-center study included 26 patients (17 females, 9 males) with recurrent patellar instability and Dejour type A, B, or C trochlear dysplasia. All demonstrated a distally deepened trochlear groove on MRI and underwent TTO-DM. Patients were followed for a minimum of 4 years (mean, 8.6 years). Outcome measures included the Kujala and Lysholm scores, radiographic assessment of the CD index and Kellgren–Lawrence grade, complications, range of motion, and pain during squatting. Results Kujala scores improved from 60.1 ± 18.7 to 93.8 ± 7.1 (p < 0.0001), and Lysholm scores increased from 59.5 ± 20.7 to 93.8 ± 7.9 (p < 0.0001). The mean CD index decreased from 1.2 to 0.88 postoperatively. No patellar redislocations or progression of patellofemoral osteoarthritis were observed. One superficial infection resolved with oral antibiotics, and one tibial tubercle fracture was successfully managed with plate fixation. Four patients had delayed recovery but returned to full function without long-term sequelae. Conclusion TTO-DM led to excellent functional outcomes and complete redislocation prevention, even in patients with CD indices ≤ 1.2. These findings suggest that surgical indications for distalization may be expanded based on trochlear morphology rather than CD index alone. Although limited by its retrospective design and small sample size, this study provides one of the longest follow-ups supporting this approach in patellofemoral instability management. patellofemoral instability tibial tuberosity osteotomy distalization trochlear dysplasia Caton–Deschamps index long-term outcomes Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Lateral patellar instability is a multifactorial clinical problem that requires a detailed understanding of anatomical and physiological contributors to provide individualized treatment.¹ The etiology often involves a combination of structural abnormalities and soft tissue dysfunction. Key anatomical risk factors include an increased tibial tuberosity–trochlear groove (TT–TG) distance,² trochlear dysplasia,³ hypermobility spectrum disorders (HSD),⁴ medial patellofemoral ligament (MPFL) insufficiency,⁵ and patella alta, commonly measured by an elevated Caton–Deschamps (CD) index.⁶ These abnormalities can alter patellofemoral joint (PFJ) mechanics and predispose patients to instability.⁷ Among the surgical options available, tibial tuberosity osteotomy with distalization and medialization (TTO-DM) offers a biomechanically sound technique to restore patellar tracking and congruency within the trochlear groove.⁸ Traditionally, distalization is indicated when the CD index exceeds 1.2,⁹ and medialization is recommended for TT–TG distances greater than 13 mm, as measured on MRI.¹⁰ However, our clinical experience suggests that in some patients with recurrent patellar instability—particularly those with trochlear dysplasia and a distally deepening trochlear groove—symptoms may persist despite a CD index within the normal range. In such cases, the traditional reliance on patellar height measurements may be insufficient. We hypothesize that the morphology of the trochlear groove, especially when the deepest point lies distally, may play a more relevant role in selecting candidates for distalizing TTO than the CD index alone. Therefore, the purpose of this retrospective case series was to evaluate the long-term safety, efficacy, and reproducibility of TTO-DM in patients with Dejour type A, B, or C trochlear dysplasia, including those with CD indices ≤ 1.2. We further aimed to assess whether trochlear morphology could serve as an extended indication for distalization, even in the absence of classic patella alta criteria. Material & Methods This retrospective study included 26 patients who met the predefined inclusion criteria. The cohort comprised 9 males (34.6%) and 17 females (65.4%), with a median age at surgery of 25 years and a mean age of 27 years (Table 1). Table 1. Demographic characteristics and scores before/after treatment. Table 1. Demographic characteristics and clinical outcomes before and after tibial tuberosity osteotomy with distalization and medialization (TTO-DM). Values are presented as mean ± standard deviation unless otherwise noted. Mean age (years, ±SD) 26,9 (± 6,8) Male/female (n) 9 / 17 Male/female (percentage of total) 34,6 / 65,4 Kujala Score preoperatively 60,1 (± 18,7) Kujala Score postoperatively 93,8 (± 7,1) Lysholm Score preoperatively 59,5 (± 20,7) Lysholm Score postoperatively 93,8 (± 7,9) Inclusion Criteria Patients were eligible for inclusion if they fulfilled all of the following: a) recurrent lateral patellar instability with a history of at least two documented dislocations; b) Dejour type A, B, or C trochlear dysplasia; c) presence of a trochlear groove deepening distally, confirmed on axial MRI slices (Figure 1); d) minimum follow-up of 4 years after tibial tuberosity osteotomy with distalization and medialization (TTO-DM). Exclusion Criteria Patients were excluded if they met any of the following: a) prior surgical intervention on the index knee; b) Dejour type D trochlear dysplasia;⁹ ¹² c) chondral lesions graded ≥2 on any articular surface per the International Cartilage Repair Society (ICRS) classification; d) advanced osteoarthritis graded 3 or 4 based on the Kellgren–Lawrence scale;¹³ e) severe torsional deformities of the femur or tibia noted during clinical examination. Out of 43 patients who met the inclusion criteria, 12 were excluded due to lack of consent, 3 had unrelated traumatic injuries to the index knee, and 2 withdrew their consent during follow-up, yielding a final study cohort of 26 patients. Preoperative Evaluation Patient history was reviewed for documented episodes of patellar dislocation. All patients underwent standardized anteroposterior and true lateral radiographs, along with axial MRI. Clinical examination included testing for lateral patellar apprehension and patellar subluxation. The Caton–Deschamps (CD) index⁶ was measured on lateral radiographs. Trochlear dysplasia was classified according to the Dejour system⁹ using radiographic imaging, while trochlear morphology (specifically, distal groove deepening) was assessed on sequential axial MRI slices. Radiographs were also analyzed for signs of patellofemoral osteoarthritis using the Kellgren–Lawrence grading system. Outcomes and Follow-Up Patients were assessed for early and late postoperative complications. Physical examination focused on the presence of a J-sign, lateral apprehension, pain during squatting, and knee range of motion. Functional outcomes were evaluated retrospectively using the Kujala and Lysholm scores. Follow-up radiographs were obtained to assess postoperative changes in CD index and progression of joint degeneration (Figure 2). Operative Technique All procedures were performed under general anesthesia and tourniquet control. A diagnostic arthroscopy was conducted initially to identify and treat any intra-articular abnormalities not previously detected on imaging. Tibial Tuberosity Osteotomy The tibial tuberosity was exposed, and a complete osteotomy was performed, creating a rectangular bone block measuring approximately 40 mm in length and 15 mm in width Soft tissue releases were performed proximally at the patellar apex to mobilize the patella both medially and laterally. An L-shaped osteotomy was then fashioned based on preoperative measurements for the desired amount of distalization and medialization (Figure 4). The tuberosity was relocated to the planned position and fixed with two cortical screws using compression technique. The excised L-shaped bone segment was rotated 180° and inserted into the remaining osteotomy gap to provide structural support and enhance healing (Figure The bone block was compressed and stabilized. On average, the tibial tuberosity was distalized by 8 mm (range, 6–14 mm) and medialized by 7.5 mm (range, 5–14 mm). MPFL Reconstruction In all patients, medial patellofemoral ligament (MPFL) reconstruction was performed using an autologous gracilis tendon graft. The graft was fixed to the femur with an interference screw and to the patella using soft tissue absorbable sutures.⁸ Postoperative Rehabilitation Postoperatively, the knee was immobilized in a long, hinged brace locked in 0–10° range of motion (ROM) for the first two weeks. Isometric quadriceps and hamstring exercises were initiated on postoperative day one. Weight-bearing was permitted as tolerated. From weeks 3–4, ROM was increased to 60°, progressing to 90° by week 6. Active ROM exercises were then introduced. Full ROM was gradually achieved over subsequent weeks according to patient tolerance and physiotherapy progression. Statistical analysis Statistical analyses were performed using GraphPad Prism software (version 7.04; GraphPad Software Inc., San Diego, CA, USA). The distribution of continuous variables was assessed using the Shapiro–Wilk test. Due to non-normal distribution in some parameters, the Mann–Whitney U test was employed to evaluate differences between preoperative and postoperative scores. A p-value of <0.05 was considered statistically significant. Continuous variables are presented as mean ± standard deviation (SD). Results At a minimum of 4 years postoperatively (mean follow-up: 8.6 years; range, 4–13 years), significant improvements were observed in both clinical outcome scores. The mean Kujala score increased from 60.1 ± 18.7 preoperatively to 93.8 ± 7.1 at final follow-up (p < 0.0001; Fig. 6 ). The mean Lysholm score similarly improved from 59.5 ± 20.7 to 93.8 ± 7.9 (p < 0.0001; Fig. 7 ). The Caton–Deschamps (CD) index decreased from a preoperative mean of 1.2 (range, 1.0–1.56) to 0.88 (range, 0.6–1.0) postoperatively, reflecting successful distalization. Notably, all patients had a positive patellar apprehension test preoperatively, which was negative in all cases at final follow-up. All patients regained full range of motion (ROM) and were able to perform pain-free squats. The postoperative clinical evaluation showed complete resolution of the J-sign in all cases. No cases of patellar redislocation or tibial tuberosity nonunion were observed. One patient developed a superficial surgical site infection, which resolved with oral antibiotic therapy. Intraoperatively, eight patients were found to have patellar or trochlear chondral lesions graded ≤ 2° per the International Cartilage Repair Society (ICRS) scale. These lesions were treated with debridement during arthroscopy. One intraoperative tibial tuberosity fracture occurred and required plate fixation with screws. The fracture healed without further complication. Four patients experienced prolonged recovery of full ROM, requiring more than 4 months of physiotherapy, although all ultimately regained full mobility. No progression of patellofemoral osteoarthritis was observed radiographically based on Kellgren–Lawrence classification during final follow-up. Discussion Patellofemoral instability remains a complex condition requiring comprehensive assessment, including advanced imaging and individualized surgical planning. In patients with recurrent lateral patellar dislocation associated with patella alta or Dejour type A–C trochlear dysplasia, tibial tuberosity osteotomy with distalization and medialization (TTO-DM) has emerged as a reliable surgical approach. Our findings suggest that the key factor guiding the decision to perform distalization may not be the Caton–Deschamps (CD) index alone, but rather the morphology of the trochlear groove—specifically, the presence of a distally deepening trochlear sulcus. In such cases, lowering the patella enables engagement with the bony groove earlier in flexion, enhancing patellar stability. Medialization addresses excessive lateralizing forces during motion, particularly in patients with increased tibial tuberosity–trochlear groove (TT–TG) distance. Numerous studies confirm the predictive value of CD index, TT–TG distance, and trochlear dysplasia for recurrent instability.² Balcarek et al. introduced the Patellar Instability Severity Score (PISS), which incorporates these anatomical risk factors and demonstrated a fivefold increased risk of redislocation in high-risk patients.¹⁴ In contrast, torsional deformities of the femur or tibia were not associated with redislocation risk and were therefore not considered in our patient selection. The rationale for including patients with CD index ≤ 1.2 stems from Caton’s original description, which defined the normal range of patellar height as 0.6–1.2.⁶ Within this “safe zone,” distalization can be performed without inducing patella baja or related complications. While traditional indications for distalization restrict the procedure to CD > 1.2, as advocated by the Lyon School of Knee Surgery and others,⁸ ¹⁰ ¹⁵ our results challenge this paradigm. Schneider et al. reported good outcomes with isolated MPFL reconstruction, but only in patients without high-risk anatomical factors.¹⁶ In contrast, systematic reviews by Jackson et al.⁵ and Saltzman et al.¹⁹ demonstrate significantly higher failure and complication rates when MPFL reconstruction is performed in the presence of anatomical risk factors, particularly without addressing patellar height or trochlear morphology. Our results further support this position: TTO-DM was effective even in patients with CD < 1.2, without leading to complications such as anterior knee pain, stiffness, or osteoarthritis progression. Peng Su et al.¹⁰ reported favorable outcomes using TTO in over 100 knees, but restricted the indication to CD ≥ 1.3. Their conclusion—that trochlear dysplasia may be more predictive of poor outcomes than patellar height or TT–TG—aligns with our experience and supports expanding surgical indications based on trochlear morphology. Longo et al.⁸ in their 2016 systematic review confirmed the safety of TTO, reporting functional failure rates below 9% and no major complications. However, no absolute threshold for surgical indication was defined, leaving space for evidence such as ours to refine these criteria. Other authors have described technically similar procedures. Bayoumi et al.¹⁷ performed a comparable osteotomy but excluded patients with prior patellar dislocation—our population of interest. Rood et al.¹⁸ evaluated a V-shaped osteotomy in patients with CD > 1.2 but excluded TT–TG correction and had only 4 months of follow-up, limiting comparability. Despite these differences, their reported 0.05% complication rate supports the low risk of fully detached tuberosity osteotomy, as further confirmed by our own single case (3.8%). Finally, Saltzman et al.¹⁹ reported 14 tibial tubercle fractures (1.3%) and 2 intraoperative complications (0.2%) across a large series. In our study, only 1 fracture occurred among 26 patients (3.8%)—comparable or lower than reported rates. Limitations This study has several limitations. Its retrospective design and reliance on patient-reported outcome measures introduce the potential for recall bias. Due to the long follow-up period, minor complications or transient symptoms may have gone unreported. Additionally, the relatively small sample size and absence of a control group limit the generalizability of the results and prevents from drawing robust conclusions. Larger, prospective comparative studies are needed to confirm these findings and define refined surgical indications. Conclusion Tibial tuberosity osteotomy with distalization and medialization (TTO-DM) might be a safe, effective, and durable surgical treatment for recurrent patellofemoral instability in selected patients with trochlear dysplasia (Dejour type A–C) and varying patellar height. Over a mean follow-up of 8.6 years, significant improvements were observed in functional scores, with no cases of redislocation or progression of osteoarthritis. Notably, distalization was well tolerated even in patients with CD indices below 1.2, suggesting that trochlear morphology—rather than patellar height alone—should guide surgical decision-making. These findings support the broader application of TTO-DM in appropriately selected patients with structural risk factors for instability. Declarations Ethical Approval and adherence to the declaration of Helsinki This study was conducted in accordance with the ethical standards of the institutional and national research committee and with the 1964 Declaration of Helsinki and its later amendments. Ethical approval was obtained from the Bioethics Committee of the Medical Chamber in Bielsko-Biała, Poland. All participants provided written informed consent prior to inclusion in the study Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests. Funding This research received no specific grant from any funding agency in the public , commercial, or not-for-profit sectors. Authors contributions MP designed the study, collected data and wrote the manuscript, AB, WS and AS performed surgical procedures, PP helped collecting data and prepped the manuscript for final publication. LB performed statistical analysis. All authors contributed to manuscript writing and approved the final version. References Jenny JY, Jenny G, Jaeger JH. Les patella douloureuses non instables: opération de Maquet. Orthop Traumatol. 1994;4(4):201–203. Dejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: An anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994;2(1):19–26. Dejour H, Walch G, Nove-Josserand L, Guier C. Dysplasia of the femoral trochlea. Rev Chir Orthop Reparatrice Appar Mot. 1990;76(1):45–54. PMID: 2140459. Malfait F, Francomano C, Byers P, et al. The 2017 international classification of the Ehlers–Danlos syndromes. Am J Med Genet C Semin Med Genet. 2017;175(1):8–26. PMID: 28306229. Jackson GR, Tuthill T, Gopinatth V, et al. Complication rates after medial patellofemoral ligament reconstruction range from 0% to 32% with 0% to 11% recurrent instability: a systematic review. Arthroscopy. 2023;39(5):1345–1356. Caton J, Dejour H, LeCoultre B, et al. Patella infera: Apropos of 128 cases. Rev Chir Orthop Reparatrice Appar Mot. 1982;68(5):317–325. PMID: 6216535. McLaughlin M, Flanigan D, Beck P, Siston P. Guidelines for treatment of lateral patella dislocations in skeletally mature patients. Am J Orthop (Belle Mead NJ). 2017;46(2):82–89. PMID: 28437505. Longo UG, Berton A, Salvatore G, et al. Medial patellofemoral ligament reconstruction combined with bony procedures for patellar instability: current indications, outcomes, and complications. Arthroscopy. 2016;32(7):1421–1427. Dejour D, Le Coultre B. Osteotomies in patellofemoral instabilities. Sports Med Arthrosc Rev. 2018;26(1):8–15. Su P, Liu X, Jian N, Li J, Fu W. Clinical outcomes and predictive factors for failure with MPFL reconstruction combined with tibial tubercle osteotomy and lateral retinacular release for recurrent patellar instability. BMC Musculoskelet Disord. 2021;22(1):632. Schneider DK, Grawe B, Magnussen RA, et al. Outcomes after isolated medial patellofemoral ligament reconstruction for recurrent lateral patellar dislocations: a systematic review and meta-analysis. Am J Sports Med. 2016;44(11):2993–3005. Dejour D, Reynaud P, LeCoultre B. Douleurs et instabilité rotulienne: Essai de classification. Med Hyg. 1998;56(2217):1466–1471. Kellgren JH, Lawrence JS. Radiological assessment of osteo-arthrosis. Ann Rheum Dis. 1957;16(4):494–502. Balcarek P, Oberthür S, Hopfensitz S, et al. Which patellae are likely to redislocate? Knee Surg Sports Traumatol Arthrosc. 2014;22(10):2308–2314. Caton JH, Dejour D. Tibial tubercle osteotomy in patellofemoral instability and patellar height abnormality. Int Orthop. 2010;34(2):305–309. Stokes DJ, Elrick BP, Carpenter ML, et al. Tibial tubercle osteotomy: indications, outcomes, and complications. Curr Rev Musculoskelet Med. 2024;17(11):484–495. Bayoumi T, Van Duijvenbode DC, Benner JL, et al. Clinical improvement is achieved following tibial tubercle distomedialization for patellar maltracking and patella alta without instability. Arthrosc Sports Med Rehabil. 2021;3(3):e845–e853. Rood A, Van Sambeeck J, Koëter S, et al. A detaching, V-shaped tibial tubercle osteotomy is a safe procedure with a low complication rate. Arch Orthop Trauma Surg. 2020;140(12):1867–1872. Saltzman BM, Rao A, Erickson BJ, et al. A systematic review of 21 tibial tubercle osteotomy studies and more than 1000 knees: indications, clinical outcomes, complications, and reoperations. Am J Orthop (Belle Mead NJ). 2017;46(6):E400–E410. PMID: 29309452. 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05:36:36","extension":"html","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":70113,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7862008/v1/d7441a0daa5d5b3910a9e658.html"},{"id":95502483,"identity":"a7ca5928-c253-409a-bdf6-17e868328985","added_by":"auto","created_at":"2025-11-10 05:36:36","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":514013,"visible":true,"origin":"","legend":"\u003cp\u003eMRI in transverse planes showing distal deepening of the trochlear groove. This anatomical feature allows for improved patellofemoral joint congruence following patellar distalization.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7862008/v1/b577b4639b430da5fef941ba.png"},{"id":95529357,"identity":"3ab26ca6-5743-4800-b129-6993d4304433","added_by":"auto","created_at":"2025-11-10 10:17:01","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":385366,"visible":true,"origin":"","legend":"\u003cp\u003ePostoperative AP and lateral radiographs. The relocated tibial tubercle is fixed with two cortical screws. The rotated L-shaped bone block is visible proximal to the tuberosity. TT = tibial tubercle, PT = patellar tendon, * = transposed insertion site.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7862008/v1/8e37523e570b2676a3482f56.png"},{"id":95529231,"identity":"2ce8c473-84cb-4551-8936-6e0962f527ad","added_by":"auto","created_at":"2025-11-10 10:16:54","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":560023,"visible":true,"origin":"","legend":"\u003cp\u003eIntraoperative image showing completed tibial tuberosity osteotomy.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7862008/v1/a2f50d0d0198cc86f47fda52.png"},{"id":95528547,"identity":"63d5b290-e262-4113-9198-3891e02efa35","added_by":"auto","created_at":"2025-11-10 10:16:15","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":551417,"visible":true,"origin":"","legend":"\u003cp\u003eIntraoperative image before and after osteotomy. The L-shaped bone block is rotated and inserted into the gap created by tuberosity realignment.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7862008/v1/5c6fba7d19bcb5751f0f20ca.png"},{"id":95502495,"identity":"4696d836-12d8-44b9-8047-5c6096657da6","added_by":"auto","created_at":"2025-11-10 05:36:36","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":736704,"visible":true,"origin":"","legend":"\u003cp\u003eIntraoperative image showing L-shaped bone block harvested from the tibial tubercle. The rotated L-shaped bone block is visible proximal to the tuberosity. TT = tibial tubercle, PT = patellar tendon, * = transposed insertion site.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7862008/v1/f8248c3c61ffbacb12c93d9b.png"},{"id":95527810,"identity":"617c1099-54e2-4216-8de5-1364f707f3e9","added_by":"auto","created_at":"2025-11-10 10:14:54","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":19838,"visible":true,"origin":"","legend":"\u003cp\u003eKujala score before and after TTO-DM. Significant improvement observed (p \u0026lt; 0.0001, Mann–Whitney test). Mean values shown with blue lines, standard deviations with red error bars.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7862008/v1/5465378bb0836b667f8d0b82.png"},{"id":95502490,"identity":"4362c5f9-9061-4b2b-a3d6-ff5ece5749f4","added_by":"auto","created_at":"2025-11-10 05:36:36","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":20570,"visible":true,"origin":"","legend":"\u003cp\u003eLysholm score before and after TTO-DM. Significant improvement observed (p \u0026lt; 0.0001, Mann–Whitney test). Mean values shown with blue lines, standard deviations with red error bars.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7862008/v1/ee6df2887df65543bb600698.png"},{"id":96253380,"identity":"abb120f0-83a3-4e09-955e-97f84c34771a","added_by":"auto","created_at":"2025-11-19 07:42:23","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4360281,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7862008/v1/6debc698-f689-47ea-b26d-baa80bf95ff4.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Expanding the Role of Tibial Tuberosity Osteotomy with Distalization and Medialization: Long- Term Success in Patellofemoral Instability Without Redislocations with a mean follow-up of 8.6 years – A Retrospective Case Series Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLateral patellar instability is a multifactorial clinical problem that requires a detailed understanding of anatomical and physiological contributors to provide individualized treatment.\u0026sup1; The etiology often involves a combination of structural abnormalities and soft tissue dysfunction. Key anatomical risk factors include an increased tibial tuberosity\u0026ndash;trochlear groove (TT\u0026ndash;TG) distance,\u0026sup2; trochlear dysplasia,\u0026sup3; hypermobility spectrum disorders (HSD),⁴ medial patellofemoral ligament (MPFL) insufficiency,⁵ and patella alta, commonly measured by an elevated Caton\u0026ndash;Deschamps (CD) index.⁶ These abnormalities can alter patellofemoral joint (PFJ) mechanics and predispose patients to instability.⁷\u003c/p\u003e\u003cp\u003eAmong the surgical options available, tibial tuberosity osteotomy with distalization and medialization (TTO-DM) offers a biomechanically sound technique to restore patellar tracking and congruency within the trochlear groove.⁸ Traditionally, distalization is indicated when the CD index exceeds 1.2,⁹ and medialization is recommended for TT\u0026ndash;TG distances greater than 13 mm, as measured on MRI.\u0026sup1;⁰\u003c/p\u003e\u003cp\u003eHowever, our clinical experience suggests that in some patients with recurrent patellar instability\u0026mdash;particularly those with trochlear dysplasia and a distally deepening trochlear groove\u0026mdash;symptoms may persist despite a CD index within the normal range. In such cases, the traditional reliance on patellar height measurements may be insufficient. We hypothesize that the morphology of the trochlear groove, especially when the deepest point lies distally, may play a more relevant role in selecting candidates for distalizing TTO than the CD index alone.\u003c/p\u003e\u003cp\u003eTherefore, the purpose of this retrospective case series was to evaluate the long-term safety, efficacy, and reproducibility of TTO-DM in patients with Dejour type A, B, or C trochlear dysplasia, including those with CD indices\u0026thinsp;\u0026le;\u0026thinsp;1.2. We further aimed to assess whether trochlear morphology could serve as an extended indication for distalization, even in the absence of classic patella alta criteria.\u003c/p\u003e"},{"header":"Material \u0026 Methods","content":"\u003cp\u003eThis retrospective study included 26 patients who met the predefined inclusion criteria. The cohort comprised 9 males (34.6%) and 17 females (65.4%), with a median age at surgery of 25 years and a mean age of 27 years (Table 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1. Demographic characteristics and scores before/after treatment.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e Demographic characteristics and clinical outcomes before and after tibial tuberosity osteotomy with distalization and medialization (TTO-DM). Values are presented as mean \u0026plusmn; standard deviation unless otherwise noted.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 387px;\"\u003e\n \u003cp\u003eMean age (years, \u0026plusmn;SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 239px;\"\u003e\n \u003cp\u003e26,9 (\u0026plusmn; 6,8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 387px;\"\u003e\n \u003cp\u003eMale/female (n)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 239px;\"\u003e\n \u003cp\u003e9 / 17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 387px;\"\u003e\n \u003cp\u003eMale/female (percentage of total)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 239px;\"\u003e\n \u003cp\u003e34,6 / 65,4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 387px;\"\u003e\n \u003cp\u003eKujala Score preoperatively\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 239px;\"\u003e\n \u003cp\u003e60,1 (\u0026plusmn; 18,7)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 387px;\"\u003e\n \u003cp\u003eKujala Score postoperatively\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 239px;\"\u003e\n \u003cp\u003e93,8 (\u0026plusmn; 7,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 387px;\"\u003e\n \u003cp\u003eLysholm Score preoperatively\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 239px;\"\u003e\n \u003cp\u003e59,5 (\u0026plusmn; 20,7)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 387px;\"\u003e\n \u003cp\u003eLysholm Score postoperatively\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 239px;\"\u003e\n \u003cp\u003e93,8 (\u0026plusmn; 7,9)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eInclusion Criteria\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatients were eligible for inclusion if they fulfilled all of the following:\u003cbr\u003e\u0026nbsp;a) recurrent lateral patellar instability with a history of at least two documented dislocations;\u003cbr\u003e\u0026nbsp;b) Dejour type A, B, or C trochlear dysplasia;\u003cbr\u003e\u0026nbsp;c) presence of a trochlear groove deepening distally, confirmed on axial MRI slices (Figure 1);\u003c/p\u003e\n\u003cp\u003ed) minimum follow-up of 4 years after tibial tuberosity osteotomy with distalization and medialization (TTO-DM).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExclusion Criteria\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatients were excluded if they met any of the following:\u003cbr\u003e\u0026nbsp;a) prior surgical intervention on the index knee;\u003cbr\u003e\u0026nbsp;b) Dejour type D trochlear dysplasia;⁹ \u0026sup1;\u0026sup2;\u003cbr\u003e\u0026nbsp;c) chondral lesions graded \u0026ge;2 on any articular surface per the International Cartilage Repair Society (ICRS) classification;\u003cbr\u003e\u0026nbsp;d) advanced osteoarthritis graded 3 or 4 based on the Kellgren\u0026ndash;Lawrence scale;\u0026sup1;\u0026sup3;\u003cbr\u003e\u0026nbsp;e) severe torsional deformities of the femur or tibia noted during clinical examination.\u003c/p\u003e\n\u003cp\u003eOut of 43 patients who met the inclusion criteria, 12 were excluded due to lack of consent, 3 had unrelated traumatic injuries to the index knee, and 2 withdrew their consent during follow-up, yielding a final study cohort of 26 patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreoperative Evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatient history was reviewed for documented episodes of patellar dislocation. All patients underwent standardized anteroposterior and true lateral radiographs, along with axial MRI. Clinical examination included testing for lateral patellar apprehension and patellar subluxation. The Caton\u0026ndash;Deschamps (CD) index⁶ was measured on lateral radiographs. Trochlear dysplasia was classified according to the Dejour system⁹ using radiographic imaging, while trochlear morphology (specifically, distal groove deepening) was assessed on sequential axial MRI slices.\u003c/p\u003e\n\u003cp\u003eRadiographs were also analyzed for signs of patellofemoral osteoarthritis using the Kellgren\u0026ndash;Lawrence grading system.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOutcomes and Follow-Up\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatients were assessed for early and late postoperative complications. Physical examination focused on the presence of a J-sign, lateral apprehension, pain during squatting, and knee range of motion. Functional outcomes were evaluated retrospectively using the Kujala and Lysholm scores. Follow-up radiographs were obtained to assess postoperative changes in CD\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eindex and progression of joint degeneration (Figure 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOperative Technique\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll procedures were performed under general anesthesia and tourniquet control. A diagnostic arthroscopy was conducted initially to identify and treat any intra-articular abnormalities not previously detected on imaging.\u003c/p\u003e\n\u003ch3\u003eTibial Tuberosity Osteotomy\u003c/h3\u003e\n\u003cp\u003eThe tibial tuberosity was exposed, and a complete osteotomy was performed, creating a rectangular bone block measuring approximately 40 mm in length and 15 mm in width\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSoft tissue releases were performed proximally at the patellar apex to mobilize the patella both medially and laterally.\u003c/p\u003e\n\u003cp\u003eAn L-shaped osteotomy was then fashioned based on preoperative measurements for the desired amount of distalization and medialization (Figure 4).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The tuberosity was relocated to the planned position and fixed with two cortical screws using compression technique. The excised L-shaped bone segment was rotated 180\u0026deg; and inserted into the remaining osteotomy gap to provide structural support and enhance healing (Figure\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe bone block was compressed and stabilized. On average, the tibial tuberosity was distalized by 8 mm (range, 6\u0026ndash;14 mm) and medialized by 7.5 mm (range, 5\u0026ndash;14 mm).\u003c/p\u003e\n\u003ch3\u003eMPFL Reconstruction\u003c/h3\u003e\n\u003cp\u003eIn all patients, medial patellofemoral ligament (MPFL) reconstruction was performed using an autologous gracilis tendon graft. The graft was fixed to the femur with an interference screw and to the patella using soft tissue absorbable sutures.⁸\u003c/p\u003e\n\u003ch3\u003ePostoperative Rehabilitation\u003c/h3\u003e\n\u003cp\u003ePostoperatively, the knee was immobilized in a long, hinged brace locked in 0\u0026ndash;10\u0026deg; range of motion (ROM) for the first two weeks. Isometric quadriceps and hamstring exercises were initiated on postoperative day one. Weight-bearing was permitted as tolerated.\u003c/p\u003e\n\u003cp\u003eFrom weeks 3\u0026ndash;4, ROM was increased to 60\u0026deg;, progressing to 90\u0026deg; by week 6. Active ROM exercises were then introduced. Full ROM was gradually achieved over subsequent weeks according to patient tolerance and physiotherapy progression.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analyses were performed using GraphPad Prism software (version 7.04; GraphPad Software Inc., San Diego, CA, USA). The distribution of continuous variables was assessed using the Shapiro\u0026ndash;Wilk test. Due to non-normal distribution in some parameters, the Mann\u0026ndash;Whitney U test was employed to evaluate differences between preoperative and postoperative scores. A p-value of \u0026lt;0.05 was considered statistically significant. Continuous variables are presented as mean \u0026plusmn; standard deviation (SD).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eAt a minimum of 4 years postoperatively (mean follow-up: 8.6 years; range, 4\u0026ndash;13 years), significant improvements were observed in both clinical outcome scores. The mean Kujala score increased from 60.1\u0026thinsp;\u0026plusmn;\u0026thinsp;18.7 preoperatively to 93.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1 at final follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001; Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe mean Lysholm score similarly improved from 59.5\u0026thinsp;\u0026plusmn;\u0026thinsp;20.7 to 93.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001; Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe Caton\u0026ndash;Deschamps (CD) index decreased from a preoperative mean of 1.2 (range, 1.0\u0026ndash;1.56) to 0.88 (range, 0.6\u0026ndash;1.0) postoperatively, reflecting successful distalization. Notably, all patients had a positive patellar apprehension test preoperatively, which was negative in all cases at final follow-up. All patients regained full range of motion (ROM) and were able to perform pain-free squats. The postoperative clinical evaluation showed complete resolution of the J-sign in all cases.\u003c/p\u003e\u003cp\u003eNo cases of patellar redislocation or tibial tuberosity nonunion were observed. One patient developed a superficial surgical site infection, which resolved with oral antibiotic therapy. Intraoperatively, eight patients were found to have patellar or trochlear chondral lesions graded\u0026thinsp;\u0026le;\u0026thinsp;2\u0026deg; per the International Cartilage Repair Society (ICRS) scale. These lesions were treated with debridement during arthroscopy.\u003c/p\u003e\u003cp\u003eOne intraoperative tibial tuberosity fracture occurred and required plate fixation with screws. The fracture healed without further complication. Four patients experienced prolonged recovery of full ROM, requiring more than 4 months of physiotherapy, although all ultimately regained full mobility. No progression of patellofemoral osteoarthritis was observed radiographically based on Kellgren\u0026ndash;Lawrence classification during final follow-up.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003ePatellofemoral instability remains a complex condition requiring comprehensive assessment, including advanced imaging and individualized surgical planning. In patients with recurrent lateral patellar dislocation associated with patella alta or Dejour type A\u0026ndash;C trochlear dysplasia, tibial tuberosity osteotomy with distalization and medialization (TTO-DM) has emerged as a reliable surgical approach.\u003c/p\u003e\u003cp\u003eOur findings suggest that the key factor guiding the decision to perform distalization may not be the Caton\u0026ndash;Deschamps (CD) index alone, but rather the morphology of the trochlear groove\u0026mdash;specifically, the presence of a distally deepening trochlear sulcus. In such cases, lowering the patella enables engagement with the bony groove earlier in flexion, enhancing patellar stability. Medialization addresses excessive lateralizing forces during motion, particularly in patients with increased tibial tuberosity\u0026ndash;trochlear groove (TT\u0026ndash;TG) distance.\u003c/p\u003e\u003cp\u003eNumerous studies confirm the predictive value of CD index, TT\u0026ndash;TG distance, and trochlear dysplasia for recurrent instability.\u0026sup2; Balcarek et al. introduced the Patellar Instability Severity Score (PISS), which incorporates these anatomical risk factors and demonstrated a fivefold increased risk of redislocation in high-risk patients.\u0026sup1;⁴ In contrast, torsional deformities of the femur or tibia were not associated with redislocation risk and were therefore not considered in our patient selection.\u003c/p\u003e\u003cp\u003eThe rationale for including patients with CD index\u0026thinsp;\u0026le;\u0026thinsp;1.2 stems from Caton\u0026rsquo;s original description, which defined the normal range of patellar height as 0.6\u0026ndash;1.2.⁶ Within this \u0026ldquo;safe zone,\u0026rdquo; distalization can be performed without inducing patella baja or related complications. While traditional indications for distalization restrict the procedure to CD\u0026thinsp;\u0026gt;\u0026thinsp;1.2, as advocated by the Lyon School of Knee Surgery and others,⁸ \u0026sup1;⁰ \u0026sup1;⁵ our results challenge this paradigm.\u003c/p\u003e\u003cp\u003eSchneider et al. reported good outcomes with isolated MPFL reconstruction, but only in patients without high-risk anatomical factors.\u0026sup1;⁶ In contrast, systematic reviews by Jackson et al.⁵ and Saltzman et al.\u0026sup1;⁹ demonstrate significantly higher failure and complication rates when MPFL reconstruction is performed in the presence of anatomical risk factors, particularly without addressing patellar height or trochlear morphology. Our results further support this position: TTO-DM was effective even in patients with CD\u0026thinsp;\u0026lt;\u0026thinsp;1.2, without leading to complications such as anterior knee pain, stiffness, or osteoarthritis progression.\u003c/p\u003e\u003cp\u003ePeng Su et al.\u0026sup1;⁰ reported favorable outcomes using TTO in over 100 knees, but restricted the indication to CD\u0026thinsp;\u0026ge;\u0026thinsp;1.3. Their conclusion\u0026mdash;that trochlear dysplasia may be more predictive of poor outcomes than patellar height or TT\u0026ndash;TG\u0026mdash;aligns with our experience and supports expanding surgical indications based on trochlear morphology.\u003c/p\u003e\u003cp\u003eLongo et al.⁸ in their 2016 systematic review confirmed the safety of TTO, reporting functional failure rates below 9% and no major complications. However, no absolute threshold for surgical indication was defined, leaving space for evidence such as ours to refine these criteria.\u003c/p\u003e\u003cp\u003eOther authors have described technically similar procedures. Bayoumi et al.\u0026sup1;⁷ performed a comparable osteotomy but excluded patients with prior patellar dislocation\u0026mdash;our population of interest. Rood et al.\u0026sup1;⁸ evaluated a V-shaped osteotomy in patients with CD\u0026thinsp;\u0026gt;\u0026thinsp;1.2 but excluded TT\u0026ndash;TG correction and had only 4 months of follow-up, limiting comparability. Despite these differences, their reported 0.05% complication rate supports the low risk of fully detached tuberosity osteotomy, as further confirmed by our own single case (3.8%).\u003c/p\u003e\u003cp\u003eFinally, Saltzman et al.\u0026sup1;⁹ reported 14 tibial tubercle fractures (1.3%) and 2 intraoperative complications (0.2%) across a large series. In our study, only 1 fracture occurred among 26 patients (3.8%)\u0026mdash;comparable or lower than reported rates.\u003c/p\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eLimitations\u003c/h2\u003e\u003cp\u003eThis study has several limitations. Its retrospective design and reliance on patient-reported outcome measures introduce the potential for recall bias. Due to the long follow-up period, minor complications or transient symptoms may have gone unreported. Additionally, the relatively small sample size and absence of a control group limit the generalizability of the results and prevents from drawing robust conclusions. Larger, prospective comparative studies are needed to confirm these findings and define refined surgical indications.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eTibial tuberosity osteotomy with distalization and medialization (TTO-DM) might be a safe, effective, and durable surgical treatment for recurrent patellofemoral instability in selected patients with trochlear dysplasia (Dejour type A–C) and varying patellar height. Over a mean follow-up of 8.6 years, significant improvements were observed in functional scores, with no cases of redislocation or progression of osteoarthritis. Notably, distalization was well tolerated even in patients with CD indices below 1.2, suggesting that trochlear morphology—rather than patellar height alone—should guide surgical decision-making. These findings support the broader application of TTO-DM in appropriately selected patients with structural risk factors for instability.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical Approval and adherence to the declaration of Helsinki\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted in accordance with the ethical standards of the institutional and national research committee and with the 1964 Declaration of Helsinki and its later amendments. Ethical approval was obtained from the Bioethics Committee of the Medical Chamber in Bielsko-Biała, Poland. All participants provided written informed consent prior to inclusion in the study\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no specific grant from any funding agency in the public , commercial, or not-for-profit sectors.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMP designed the study, collected data and wrote the manuscript, AB, WS and AS performed surgical procedures, PP helped collecting data and prepped the manuscript for final publication. LB performed statistical analysis. All authors contributed to manuscript writing and approved the final version.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eJenny JY, Jenny G, Jaeger JH. Les patella douloureuses non instables: op\u0026eacute;ration de Maquet. Orthop Traumatol. 1994;4(4):201\u0026ndash;203.\u003c/li\u003e\n \u003cli\u003eDejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: An anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994;2(1):19\u0026ndash;26.\u003c/li\u003e\n \u003cli\u003eDejour H, Walch G, Nove-Josserand L, Guier C. Dysplasia of the femoral trochlea. Rev Chir Orthop Reparatrice Appar Mot. 1990;76(1):45\u0026ndash;54. PMID: 2140459.\u003c/li\u003e\n \u003cli\u003eMalfait F, Francomano C, Byers P, et al. The 2017 international classification of the Ehlers\u0026ndash;Danlos syndromes. Am J Med Genet C Semin Med Genet. 2017;175(1):8\u0026ndash;26. PMID: 28306229.\u003c/li\u003e\n \u003cli\u003eJackson GR, Tuthill T, Gopinatth V, et al. Complication rates after medial patellofemoral ligament reconstruction range from 0% to 32% with 0% to 11% recurrent instability: a systematic review. Arthroscopy. 2023;39(5):1345\u0026ndash;1356.\u003c/li\u003e\n \u003cli\u003eCaton J, Dejour H, LeCoultre B, et al. Patella infera: Apropos of 128 cases. Rev Chir Orthop Reparatrice Appar Mot. 1982;68(5):317\u0026ndash;325. PMID: 6216535.\u003c/li\u003e\n \u003cli\u003eMcLaughlin M, Flanigan D, Beck P, Siston P. Guidelines for treatment of lateral patella dislocations in skeletally mature patients. Am J Orthop (Belle Mead NJ). 2017;46(2):82\u0026ndash;89. PMID: 28437505.\u003c/li\u003e\n \u003cli\u003eLongo UG, Berton A, Salvatore G, et al. Medial patellofemoral ligament reconstruction combined with bony procedures for patellar instability: current indications, outcomes, and complications. Arthroscopy. 2016;32(7):1421\u0026ndash;1427.\u003c/li\u003e\n \u003cli\u003eDejour D, Le Coultre B. Osteotomies in patellofemoral instabilities. Sports Med Arthrosc Rev. 2018;26(1):8\u0026ndash;15.\u003c/li\u003e\n \u003cli\u003eSu P, Liu X, Jian N, Li J, Fu W. Clinical outcomes and predictive factors for failure with MPFL reconstruction combined with tibial tubercle osteotomy and lateral retinacular release for recurrent patellar instability. BMC Musculoskelet Disord. 2021;22(1):632.\u003c/li\u003e\n \u003cli\u003eSchneider DK, Grawe B, Magnussen RA, et al. Outcomes after isolated medial patellofemoral ligament reconstruction for recurrent lateral patellar dislocations: a systematic review and meta-analysis. Am J Sports Med. 2016;44(11):2993\u0026ndash;3005.\u003c/li\u003e\n \u003cli\u003eDejour D, Reynaud P, LeCoultre B. Douleurs et instabilit\u0026eacute; rotulienne: Essai de classification. Med Hyg. 1998;56(2217):1466\u0026ndash;1471.\u003c/li\u003e\n \u003cli\u003eKellgren JH, Lawrence JS. Radiological assessment of osteo-arthrosis. Ann Rheum Dis. 1957;16(4):494\u0026ndash;502.\u003c/li\u003e\n \u003cli\u003eBalcarek P, Oberth\u0026uuml;r S, Hopfensitz S, et al. Which patellae are likely to redislocate? Knee Surg Sports Traumatol Arthrosc. 2014;22(10):2308\u0026ndash;2314.\u003c/li\u003e\n \u003cli\u003eCaton JH, Dejour D. Tibial tubercle osteotomy in patellofemoral instability and patellar height abnormality. Int Orthop. 2010;34(2):305\u0026ndash;309.\u003c/li\u003e\n \u003cli\u003eStokes DJ, Elrick BP, Carpenter ML, et al. Tibial tubercle osteotomy: indications, outcomes, and complications. Curr Rev Musculoskelet Med. 2024;17(11):484\u0026ndash;495.\u003c/li\u003e\n \u003cli\u003eBayoumi T, Van Duijvenbode DC, Benner JL, et al. Clinical improvement is achieved following tibial tubercle distomedialization for patellar maltracking and patella alta without instability. Arthrosc Sports Med Rehabil. 2021;3(3):e845\u0026ndash;e853.\u003c/li\u003e\n \u003cli\u003eRood A, Van Sambeeck J, Ko\u0026euml;ter S, et al. A detaching, V-shaped tibial tubercle osteotomy is a safe procedure with a low complication rate. Arch Orthop Trauma Surg. 2020;140(12):1867\u0026ndash;1872.\u003c/li\u003e\n \u003cli\u003eSaltzman BM, Rao A, Erickson BJ, et al. A systematic review of 21 tibial tubercle osteotomy studies and more than 1000 knees: indications, clinical outcomes, complications, and reoperations. Am J Orthop (Belle Mead NJ). 2017;46(6):E400\u0026ndash;E410. PMID: 29309452.\u003cstrong\u003e\u003c/strong\u003e\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":"patellofemoral instability, tibial tuberosity osteotomy, distalization, trochlear dysplasia, Caton–Deschamps index, long-term outcomes","lastPublishedDoi":"10.21203/rs.3.rs-7862008/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7862008/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e\u003cp\u003ePatellofemoral instability is a multifactorial condition influenced by anatomical abnormalities and soft tissue dysfunction. Distalization of the tibial tuberosity is classically reserved for patients with patella alta, typically defined by a Caton\u0026ndash;Deschamps (CD) index\u0026thinsp;\u0026gt;\u0026thinsp;1.2. However, clinical experience suggests that certain patients with lower CD indices but distally deepening trochlear morphology may also benefit. This study is aimed to evaluate the long-term outcomes of tibial tuberosity osteotomy with distalization and medialization (TTO-DM) in patients with recurrent lateral patellar instability, regardless of patellar height.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMaterials and Methods\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThis retrospective single-center study included 26 patients (17 females, 9 males) with recurrent patellar instability and Dejour type A, B, or C trochlear dysplasia. All demonstrated a distally deepened trochlear groove on MRI and underwent TTO-DM. Patients were followed for a minimum of 4 years (mean, 8.6 years). Outcome measures included the Kujala and Lysholm scores, radiographic assessment of the CD index and Kellgren\u0026ndash;Lawrence grade, complications, range of motion, and pain during squatting.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e\u003cp\u003eKujala scores improved from 60.1\u0026thinsp;\u0026plusmn;\u0026thinsp;18.7 to 93.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), and Lysholm scores increased from 59.5\u0026thinsp;\u0026plusmn;\u0026thinsp;20.7 to 93.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). The mean CD index decreased from 1.2 to 0.88 postoperatively. No patellar redislocations or progression of patellofemoral osteoarthritis were observed. One superficial infection resolved with oral antibiotics, and one tibial tubercle fracture was successfully managed with plate fixation. Four patients had delayed recovery but returned to full function without long-term sequelae.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e\u003cp\u003eTTO-DM led to excellent functional outcomes and complete redislocation prevention, even in patients with CD indices\u0026thinsp;\u0026le;\u0026thinsp;1.2. These findings suggest that surgical indications for distalization may be expanded based on trochlear morphology rather than CD index alone. Although limited by its retrospective design and small sample size, this study provides one of the longest follow-ups supporting this approach in patellofemoral instability management.\u003c/p\u003e","manuscriptTitle":"Expanding the Role of Tibial Tuberosity Osteotomy with Distalization and Medialization: Long- Term Success in Patellofemoral Instability Without Redislocations with a mean follow-up of 8.6 years – A Retrospective Case Series Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-10 05:36:31","doi":"10.21203/rs.3.rs-7862008/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":"fc11ac4c-f2cf-441b-bd0a-cb3de134a704","owner":[],"postedDate":"November 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-19T05:08:42+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-10 05:36:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7862008","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7862008","identity":"rs-7862008","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}