The Effect of Knee Flexion Contracture on Patient Reported Outcome Measures after Distal Femur Fractures (OTA/AO Type 33):A Multi-Center Prospective Evaluation

The Effect of Knee Flexion Contracture on Patient Reported Outcome Measures after Distal Femur Fractures (OTA/AO Type 33):A Multi-Center Prospective Evaluation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The Effect of Knee Flexion Contracture on Patient Reported Outcome Measures after Distal Femur Fractures (OTA/AO Type 33):A Multi-Center Prospective Evaluation Robert Dunbar, Margaret Cooke, Paul Tornetta III, Christopher Born, and 19 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7223366/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 OBJECTIVES: · To determine if patients with knee flexion contracture after distal femur fracture have poorer outcomes than patients who regain full knee extension. · To determine if factors such as patient age, gender, open fracture or implant used favors knee flexion contracture. METHODS: Design: Prospective, multicenter trial Setting: Twenty academic level I trauma centers Patient Selection Criteria: Patients with a distal femur fracture. Patients were evaluated for knee flexion contracture at 3, 6 and 12 months post-operatively. Outcome Measures and Comparisons: SMFA, Bother Index and EQ Health Index scores were recorded. Walking and stair climbing ability were assessed. RESULTS: · 126 patients had radiographic follow up for 12 months. There was clinical follow-up for 99 patients at 3 months, 90 patients at 6 months and 74 pts at 12 months. · Patients with full knee extension had better SMFA scores at 12 months than patients with knee flexion contracture (p = 0.308). · Bother Index (p = 0.29) and EQ Health State (p = 0.12) scores did not demonstrate a difference between patients with or without knee flexion contracture at any time point. · Patients with full knee extension had improved walking ability compared to patients with flexion contracture (p = 0.008). Patients with full knee extension had better stair climbing ability than patients with flexion contracture (p = 0.02). · Only older patient age showed a difference in likelihood of flexion contracture (p = 0.01) The rates of flexion contracture in women versus men (p = 0.51), RIMN versus LLP (p = 0.74) and open versus closed fracture (p = 0.24) were not statistically different. CONCLUSIONS: · Patients with knee flexion contractures after distal femur fracture do worse than patients who regain full extension. · Older patients with distal femur fractures are at greater risk for knee flexion contracture. LEVEL OF EVIDENCE: Level I Distal Femur fracture Knee flexion contracture patient reported outcome score Figures Figure 1 Figure 2 Figure 3 Background Loss of knee range of motion is common after distal femur fractures. 1-3 While knee extension contracture, or the loss of knee flexion, has received significant attention, less attention has been given to knee flexion contracture after fracture. 4-6 Knee flexion contracture after distal femur fractures is likely multifactorial and may be related to such factors as the severity of the original injury, the use of an external fixator, scarring and/or contracture the musculature around the knee and the knee capsule, intra-articular synovitis and arthrofibrosis formation or sagittal plane malreduction. 2 Any immobilization after fracture fixation, maintenance of the knee in flexion in the post operative period (e.g. the placement of a pillow behind the knee) or a delay in weight bearing or access to physical therapy may also contribute to the development of a knee flexion contracture. Knee flexion contracture has been recognized as an issue after surgeries like total knee arthroplasty, anterior cruciate ligament reconstruction and transtibial (below knee) amputation. 7-12 Literature from these fields, as well as studies from rehabilitation medicine have shown that knee flexion contracture alters gait biomechanics and even spine kinematics, and may lead to symptomatic dysfunction. 13-15 Patients with knee flexion contractures demonstrate a decrease in gait velocity and stride length. 7, 16-18 These patients may also require a greater and longer quadriceps force to stabilize the knee and the quadriceps may need to continue firing to prevent buckling of the limb. 17 This can lead to joint overload in the ipsilateral, and even the contralateral, knee. 14 This overload leads to greater energy expenditure (22-30% more with a 15 degree flexion contracture) as well as increased anterior knee pain. 8,15,18 After TKA, some patients develop knee contractures and do show some improvement over time, however, if contracture is present at 3 months, post operatively, particularly in older patients, it may become permanent. 8,17,19,20 Although many fracture surgeons employ strategies to avoid flexion contractures, flexion contracture remains a common issue after distal femur fracture fixation. 2 However, to the best of our knowledge there is no data regarding the effect of knee flexion contracture on functional or clinical outcomes after the operative treatment of distal femur fractures. The hypothesis of this study is that patients with flexion contractures will have poorer functional and clinical outcome scores than patients with full knee extension. The primary aim of this study was to compare validated patient reported outcome measures in patients with and without an acquired flexion contracture after operative treatment for distal femur fractures. Secondary aim were to determine if factors such as patient gender, whether the fracture was open or closed or whether a intramedullary nail or a plate and screw construct was used favored the development of knee flexion contracture. Methods This study reports on data collected from a previously published randomized multicenter trial for which Institutional Review Board (IRB) approval was obtained prior to patient recruitment. 21 All patients presented to one of twenty institutions over a 75-month period. Inclusion criteria were: skeletally mature patients 18 years of age or older who were enrolled in a prospective database with an extra-articular or simple articular split distal femur fracture (OTA/AO 33-A1, 33-A2, 33-A3, 33C1 or 33C-2), with or without metaphyseal comminution. 22 Patients were excluded from the study if they had sustained a pathologic fracture, a fracture with intra-articular comminution (beyond a simple split), bilateral distal femur fractures or ipsilateral lower extremity injury that would compromise the function of the knee, vascular injury requiring repair, or any factor precluding nail or plate fixation. Similarly, patients with a surgical delay greater than 3 week for closed fractures or greater than 24 hours for open fractures were excluded. Patients with pre-existing symptomatic knee arthritis, known pre-injury knee flexion contracture, known metabolic bone disease, and immunocompromise were also excluded. Finally, patients that were deemed unlikely to follow up (e.g. due to current or impending incarceration) and those unable to comply with post-operative rehabilitation protocols (due to head injury or mental impairment) were excluded. Patients who filled out outcome forms but were not examined in person were also excluded. All patients were treated by retrograde intramedullary nail or by locking plate. There were no combination constructs (e.g. nail-plate or dual plating) or distal femoral replacement arthroplasties performed as these were not included in the protocol of the original study that recruited these patients. 21 No specific brand of nail or plate was required and all sites used what they were using prior to the initiation of the study. All patients were placed on the same post-operative protocol for mobilization including early knee range of motion. All patients were allowed to be toe touch weight bearing immediately after the procedure; once callus was present on radiographs, partial weight-bearing was allowed and full weight-bearing was initiated when bridging callus was present on orthogonal radiographs. Flexion contracture was defined as ≥10° of loss of passive extension from neutral on physical examination to account for measurement variation and to be certain that a noticeable contracture was present. All measurements were done by local primary investigator attending orthopaedic surgeons using a goniometer. Demographic data, ambulatory ability and ability to climb stairs and walk distances were recorded. Clinical assessment of passive knee range of motion and validated outcomes including SMFA, Bother Index, and EQ Health Index were obtained at 3, 6, and 12 months postoperatively. 23,24 Clinical outcomes were measured. Stair climbing was scored on a 5 point scale modified from the Knee Society Score (Figure 1): 25 Walking ability was scored on a 6 point scale also modified from the Knee Society Score (figure 2): 25 Functional outcomes for patients with and without contractures were compared. Fisher’s Exact Test was used for categorical variables and Student’s t-tests were used for continuous variables. 26,27 Statistical significance was set at p < 0.05. Results 372 patients were screened, and 212 did not meet inclusion criteria. 160 patients were recruited and 156 patients were enrolled in the study. 21 126 patients (55 women and 71 men) aged 16-90 years (average 51 years) were enrolled and had >12 months of radiographic follow up. There was clinical data for 99 patients (44 women, 55 men) at 3 months, 90 patients (41 women, 49 men,) at 6 months and 74 patients (35 women, 39 men) at one year. 84 of 126 fractures (66.7%) were type 33-A extraarticular fractures. 42 of 123 (33.3%) were type 33-C1 or 33-C2 with simple articular splits. 33 of 126 fractures (26.2%) were open fractures, all Gustilo type II and type IIIA. The average Injury Severity Score overall was 12.6 (9-43). The overall rate of documented knee flexion contracture was 16% at 3 months and 14% at one year (so most who developed flexion contracture still it had at one year). Patients did not tend to show improvement between 3 months and one year (p = 0.67). At one year patients without knee flexion contractures had significantly better functional outcome scores than those patients with knee flexion contractures as measured by the SMFA (p = 0.038). SMFA scores at one year for patients without a flexion contracture were 22.8 versus 41.8 for patients with a knee flexion contracture (p = 0.038). These results are seen in Table 1. Notably, as the normative values for patients aged 50 years is 13.6 for both the SMFA and the Bother Index, many patients, irrespective of their knee extension, remained substantially affected by their injury at one year. 28 Furthermore, patients without a flexion contracture showed steady improvement in their SMFA score at each follow up visit while patients with flexion contracture did not show improvement in their SMFA score over time. At 3, 6, and 12 months the SMFA scores for patients without contracture were 40.3, 28.6 and 22.8, and the SMFA scores for those patients with a flexion contracture were 44.1, 55.4, 41.8 (Figure 3). Conversely, the Bother Index (p = 0.29) and EQ Health State (p = 0.12) scores did not demonstrate a difference between patients with or without a flexion contracture at any time point (Table 1 and Figure 3). Table 1: Functional Outcome at One Year Looking at functional ability, at one year patients without knee flexion contracture also did better than patients with knee flexion contracture. Specifically, patients with full knee extension demonstrated improved walking ability compared to those who had a flexion contracture (2.63 versus 4.1, p = 0.008). The typical patient at one year with full knee extension could walk more than ten blocks and the typical patient with a flexion contracture could walk fewer than five blocks (Table 1). Similarly, patients with full knee extension had better stair climbing ability than those who had a flexion contracture (2.41 versus 3.40, p = 0.02). On average, patients with full knee extension could climb stairs independently and patients with a flexion contracture required the use of a hand rail (Table 1). Of the factors evaluated, only an older age was associated with the development of a knee flexion contracture. At no time point was the type of fixation (LLP v RIMN), the patient’s gender, or whether the fracture was open or closed associated with the development of a flexion contracture. Patients without knee flexion contracture averaged 52 years of age, while patients with knee flexion contracture averaged 65 years of age, which was statistically different (p=0.01). The rate of flexion contracture at one year was 17.1% in women versus 10.5% in men (p=0.51). The rate of flexion contracture at one year was 11.8% in the RIMN group versus 16.2% for the LLP group (p=0.74). The rate of flexion contracture at one year was in patients with open fractures 23.5% versus 11.1% for closed fractures (p=0.24). These results may be seen in Table 2. Discussion While there is a paucity of data on the functional outcomes of patients with flexion contractures after distal femur fracture, there have been a significant number of studies reporting on patients with knee flexion contracture after procedures like total knee arthroplasty and ACL reconstruction (as well basic science/gait analysis reports). 4,8,9 Patients with knee flexion contractures have been shown to walk more slowly and require both more energy and more force to maintain their knees in an extended position. 14 While some patients respond well to physical therapy and other modalities (e.g. manipulation under anesthesia, or operative treatment, some flexion contractures that are present at 3 months post operatively become permanent. 8,20 Older patients seem to be at increased risk both for the development of a flexion contracture and for that contracture to become permanent. 8,17,19,20 In one study, each decade of life increased the likelihood of a flexion contracture of greater than 10 degrees by 35%. 8 In terms of functional scoring, Ritter showed that those patients with >10° of flexion contracture after TKA had significantly lower Knee Society pain and function scores when compared to patients achieving full extension. 8 Similarly, this study found that patients with distal femur fractures who failed to recover full knee extension and developed flexion contractures also did more poorly than patients who regained full extension. Specifically, patients with knee flexion contractures had worse functional outcome scoring, at least in terms of the SMFA, and they showed no improvement from 3 months to 1 year. Additionally, those with a contracture at 3 months tended to have a contracture at 1 year. Similarly, patients with knee flexion contractures did worse clinically, in terms of walking ability and stair climbing ability. Finally, with the number of patients in this study, while gender, implant chosen and whether the fracture was originally open (an indicator of higher energy mechanism) did not correlate with the development of a flexion contracture, increasing age did correlate with the development of a knee flexion contracture, similar to reports in the arthroplasty literature. Limitations of this study include the accuracy of measurement by using a goniometer, which has been noted to have some degree of inaccuracy. 29 To mitigate this effect a 10 degree cutoff for flexion contracture was chosen rather than 5 degrees, to favor investigating contractures that would be more likely to be clinically relevant. Certainly one could investigate patients with more subtle contractures to see whether those also decrease patient function, however, in this study these patients would be included in the “normal” group, further demonstrating the dysfunction of the contracture group. Another limitation is that while the benefits of a multicenter study include the potential to extrapolate a conclusion across a broader population, there is the inherent potential for heterogeneity (e.g. we delegated measurements of contracture to the individual local investigators). That said, these were all attending orthopaedic trauma surgeons who were the local primary investigators for the study. In conclusion, patients with distal femur fractures who develop flexion contractures postoperatively struggle to regain function and do worse both clinically and functionally than patients who regain full extension. Similar to total knee arthroplasty patients, older patients with distal femur fractures also seem to be at greater risk for flexion contracture than younger patients. Given that those with contracture at 3 months tended to maintain this contracture at one year post operatively, a focus on early mobility, with an emphasis placed on regaining full extension, avoiding a knee flexion contracture, rather than hoping to treat and overcome one, is particularly important in this patient group. Declarations Author Contribution PT3, CC, CB, KE, CJ, RO, WR designed studyRD , MC, and PT3 wrote and revised manuscriptAll authors except AZ and MC were primary investigators at their institutions and directed the acquisition of dataAZ was nonetheless reposnsible for data analysis and directed the acquisition at his institutionAll authors reviewed and edited manuscriptAll authors approve submitted work Data Availability Data for this project, including all data for tables & figures is available upon request. References Nasr AM, McLeod I, Sabboubeh A, Maffulli N. Conservative or surgical management of distal femur fractures.A retrospective study with a minimum five year follow up. Acta O Belg. 2000;66(5):477-83. Bishop, J, Agel, J, Dunbar RP. Predictive factors of knee stiffness after peri- articular fracture: A case-control study. JBJS Am. 2012;94(20)1833-7. Hutson JJ Jr, Zych GA. Treatment of comminuted intraarticular distal femur fractures with limited internal and external tensioned wire fixation.J Orthop Trauma 2000;14(6):405-13. Bong MR, Di Cesare PE. Stiffness after knee arthroplasty. JAAOS 2004;12:164- 71. Judet R. Mobilisation of the stiff knee. J Bone Jt Surg Br. 1959;41B:856-7. Holshen M, Lobenhoffer P. Treatment of extension contracture of the knee by quadriceps plasty (Judet procedure). Oper Orthop Traumatol. 2014;26(4):353-60. Attias M, Chevalley O, Bonnefoy-Mazure A, De Coulon G, Cheze L, Armand S. Effects of contracture on gait kinematics. Clin Biomech. 2016;33:103-10. Ritter MA, Lutgring JD, Davis KE, Berend ME, Pierson JL, Meneghini RM. The role of flexion contracture on outcomes in primary total knee arthroplasty. J Arthroplasty 2007;22:1092-6. Petsche TS, Hutchinson MR. Loss of extension after reconstruction of the anterior cruciate ligament. J Am Acad Ortho Surg. 1999.7:119-27. Scholes C, Ektas N, Harrison-Brown M, Jegatheesan M, Rajesh A, Kirwan G, Bell C. Persistent knee extension deficits are common after anterior cruciate ligament reconstruction: a systematic review and meta-analysis of randomized controlled trials. Knee Surg Sports Traumatol Arthrosc. 2023;31(8):3172-3185. Wasiak K. Analysis of prognostic factor for locomotion in patients after amputation for the tibia performed due to atherosclerotic critical limb ischemia. Orthop Traumatol Rehabil. 2005;30(7):411-7. Reichmann JP, Stevens PM, Rheinstein J, Kreuen CD. Removable rigid dressings for postoperative management of transtibial amputations: A review of published evidence. Phys Med Rehab. 2018;10:516-23. Harato K, Nagura T, Matsumoto H, Otani T, Toyama Y, Suda Y. A gait analysis of simulated knee flexion contracture to elucidate knee-spine syndrome. Gait & Posture 2008; 28: 687-692 Harato K, Nagura T, Matsumoto H, Otani T, Toyama Y, Suda Y. Knee flexion contracture will lead to mechanical overload in both limbs: A simulation study using gait analysis. The Knee 2008;15:467-472. Perry J, Antonelli D, Ford W. Analysis of knee-joint forces during flexed knee stance. J Bone Joint Surg Am. 1975. 57A:961-7 Cerny K, Perry J, Walker JM. Adaptations during the stance phase of gait for simulated flexion contractures at the knee. Orthopedics 1994;17(6):501-12. Su, EP. Fixed flexion deformity and total knee arthroplasty. J Bone Joint Surg (Br) 2012; 94-B, Supple A:112-115. Waters RL, Mulroy S. The energy expenditure of normal and pathologic gait. Gait Posture 1999;9:207–31. Goudie ST, Deakin AH, Ahmad A, Maheshwari R, Picard F. Flexion contracture following primary total knee arthroplasty: risk factors and outcomes. Orthopedics 2011;34:e855. Mitsuyasu H, Matsuda S, Miura H, Okazaki K, Fukagawa S, Iwamoto Y. Flexion contracture persists if the contracture is more than 15º at 3 months after total knee arthroplasty. J Arthroplasty. 2011;34:855-9. Dunbar RP, Egol KA, Jones CB, Ertl JP, Mullis B, Perez E, Collinge CA, Ostrum R, Humphrey C, Gardner MJ, Ricci WM, Phieffer LS, Teague D, Ertl W, Born CT, Zonno A, Siegel J, Sagi HC, Pollak A, Schmidt AH, Templeman D, Sems A, Freiss DM, Pape HC, Krieg JC, Tornetta P III. Locked lateral plating vs. retrograde nailing for distal femur fractures: A multicenter randomized trial. J Orthop Trauma. 2023;37(2):70-6. Meinberg EG, Agel J, Roberts CS, et al. Fracture and Dislocation Classification Compendium - 2018. J Orthop Trauma. 2018;32 Supplement 1 pp: S1-S170. Swiontkowski MF, Engelberg R, Martin DP et al. Short musculoskeletal function assessment questionnaire: validity, reliability, and responsiveness. J Bone Joint Surg Am. 1999;81(9):1245-60. EuroQoL Group. EuroQoL – A new facility for the measurement of health-related quality of life. Health Policy. 1990;16:199-208. Insall JN, Dorr LD, Scott RD, et al. Rationale of the Knee Society clinical rating system. Clin Orthop Rel Res. 1989;248:13-4. Fisher RA. On the interpretation of X2 from contingency tables and the calculation of P. J Roy Stat Soc. 1922;85(1):87-94. Student (Gosset WS). The probable error of a mean. Biometrika. 1908;6(1):1-25. Engelberg R, Martin DP, Agel J, Swiontkowski MF. Musculoskeletal Function Assessment: Reference values for patient and non-patient samples. J Orthop Res 1999;17:101-9. Lenssen AF, van Dam EM, Crijns YH, Verhey M, Geesink RJ, van den Brandt PA, de Bie RA. Reproducibility of goniometric measurement of the knee in the in- hospital phase following total knee arthroplasty. BMC Musculoskelet Disord 2007;8:83:1-7. Tables Table 1 and 2 are available in the Supplementary Files section. Additional Declarations No competing interests reported. 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22:38:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7223366/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7223366/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91192546,"identity":"5c37c8b9-fd55-4e57-8e83-4602a2e9e652","added_by":"auto","created_at":"2025-09-12 14:42:31","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":29829,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStair Climbing Ability\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7223366/v1/5ee6711c11f7ba78cb023355.png"},{"id":91192547,"identity":"a4cf7ae7-1cc5-435f-9764-469a30f24bd5","added_by":"auto","created_at":"2025-09-12 14:42:31","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":25620,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eWalking Ability\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7223366/v1/d29e2f945bbadc4886035c40.png"},{"id":91192551,"identity":"61df2bf2-4a84-4457-a0d8-03210b813439","added_by":"auto","created_at":"2025-09-12 14:42:31","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":79876,"visible":true,"origin":"","legend":"\u003cp\u003eSMFA Score: Note that patients without knee flexion contracture had steady improvement from 3 to 12 months post operative but patients with kneeflexion contracture did not.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7223366/v1/534a52c31ae9ce0913507239.png"},{"id":103506138,"identity":"3d36a598-6677-4692-b4d6-fef924fa014d","added_by":"auto","created_at":"2026-02-26 13:34:13","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":646128,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7223366/v1/a84ac492-6f47-48c3-8326-95782b6e0520.pdf"},{"id":91192555,"identity":"18afc563-fec5-4180-b5da-13df4eff2210","added_by":"auto","created_at":"2025-09-12 14:42:31","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":156463,"visible":true,"origin":"","legend":"","description":"","filename":"Table1and2.docx","url":"https://assets-eu.researchsquare.com/files/rs-7223366/v1/85478a3f1083d603d500e45a.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eThe Effect of Knee Flexion Contracture on Patient Reported Outcome Measures after Distal Femur Fractures (OTA/AO Type 33):A Multi-Center Prospective Evaluation\u003c/p\u003e","fulltext":[{"header":"Background","content":"\u003cp\u003eLoss of knee range of motion is common after distal femur fractures.\u003csup\u003e1-3 \u0026nbsp;\u003c/sup\u003eWhile knee extension contracture, or the loss of knee flexion, has received significant attention, less attention has been given to knee flexion contracture after fracture.\u003csup\u003e4-6\u0026nbsp;\u003c/sup\u003eKnee flexion contracture after distal femur fractures is likely multifactorial and may be related to such factors as the severity of the original injury, the use of an external fixator, scarring and/or contracture the musculature around the knee and the knee capsule, intra-articular synovitis and arthrofibrosis formation or sagittal plane malreduction.\u003csup\u003e2\u003c/sup\u003e Any immobilization after fracture fixation, maintenance of the knee in flexion in the post operative period (e.g. the placement of a pillow behind the knee) or a delay in weight bearing or access to physical therapy may also contribute to the development of a knee flexion contracture.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eKnee flexion contracture has been recognized as an issue\u0026nbsp;after surgeries like total knee arthroplasty, anterior cruciate ligament reconstruction and transtibial (below knee) amputation.\u003csup\u003e7-12 \u0026nbsp;\u003c/sup\u003eLiterature from these fields, as well as studies from rehabilitation medicine have shown that knee flexion contracture\u0026nbsp;alters gait biomechanics and even spine kinematics, and may lead to symptomatic dysfunction.\u003csup\u003e13-15 \u0026nbsp;\u003c/sup\u003ePatients with knee flexion contractures demonstrate a decrease in gait velocity and stride length.\u003csup\u003e7,\u0026nbsp;\u003c/sup\u003e\u003csup\u003e16-18\u003c/sup\u003e These patients may also require a greater and longer quadriceps force to stabilize the knee and the quadriceps may need to continue firing to prevent buckling of the limb.\u003csup\u003e17\u0026nbsp;\u003c/sup\u003e This can lead to joint overload in the ipsilateral, and even the contralateral, knee.\u003csup\u003e14\u003c/sup\u003e This overload leads to greater energy expenditure (22-30% more with a 15 degree flexion contracture) as well as increased anterior knee pain.\u003csup\u003e8,15,18\u003c/sup\u003e\u0026nbsp; After TKA, some patients develop knee contractures and do show some improvement over time, however, if contracture is present at 3 months, post operatively, particularly in older patients, it may become permanent.\u003csup\u003e8,17,19,20\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAlthough many fracture surgeons employ strategies to avoid flexion contractures, flexion contracture remains a common issue after distal femur fracture fixation.\u003csup\u003e2\u003c/sup\u003e However, to the best of our knowledge there is no data regarding the effect of knee flexion contracture on functional or clinical outcomes after the operative treatment of distal femur fractures. The hypothesis of this study is that patients with flexion contractures will have poorer functional and clinical outcome scores than patients with full knee extension. The primary aim of this study was to compare validated patient reported outcome measures in patients with and without an acquired flexion contracture after operative treatment for distal femur fractures. Secondary aim were to determine if factors such as patient gender, whether the fracture was open or closed or whether a intramedullary nail or a plate and screw construct was used favored the development of knee flexion contracture.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis study reports on data collected from a previously published randomized multicenter trial for which Institutional Review Board (IRB) approval was obtained prior to patient recruitment.\u003csup\u003e21\u0026nbsp;\u003c/sup\u003e All patients presented to one of twenty institutions over a 75-month period. Inclusion criteria were: skeletally mature patients 18 years of age or older who were enrolled in a prospective database with an extra-articular or simple articular split distal femur fracture (OTA/AO 33-A1, 33-A2, 33-A3, 33C1 or 33C-2), with or without metaphyseal comminution.\u003csup\u003e22\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePatients were excluded from the study if they had sustained a pathologic fracture, a fracture with intra-articular comminution (beyond a simple split), bilateral distal femur fractures or ipsilateral lower extremity injury that would compromise the function of the knee, vascular injury requiring repair, or any factor precluding nail or plate fixation. Similarly, patients with a surgical delay greater than 3 week for closed fractures or greater than 24 hours for open fractures were excluded. Patients with pre-existing symptomatic knee arthritis, known pre-injury knee flexion contracture, known metabolic bone disease, and immunocompromise were also excluded. Finally, patients that were deemed unlikely to follow up (e.g. due to current or impending incarceration) and those unable to comply with post-operative rehabilitation protocols (due to head injury or mental impairment) were excluded. Patients who filled out outcome forms but were not examined in person were also excluded.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll patients were treated by retrograde intramedullary nail or by locking plate. There were no combination constructs (e.g. nail-plate or dual plating) or distal femoral replacement arthroplasties performed as these were not included in the protocol of the original study that recruited these patients.\u003csup\u003e21\u003c/sup\u003e No specific brand of nail or plate was required and all sites used what they were using prior to the initiation of the study. All patients were placed on the same post-operative protocol for mobilization including early knee range of motion. All patients were allowed to be toe touch weight bearing immediately after the procedure; once callus was present on radiographs, partial weight-bearing was allowed and full weight-bearing was initiated when bridging callus was present on orthogonal radiographs.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFlexion contracture was defined as \u0026nbsp;\u0026ge;10\u0026deg; of loss of passive extension from neutral on physical examination to account for measurement variation and to be certain that a noticeable contracture was present. All measurements were done by local primary investigator attending orthopaedic surgeons using a goniometer.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDemographic data, ambulatory ability and ability to climb stairs and walk distances were recorded. Clinical assessment of passive knee range of motion and validated outcomes including SMFA, Bother Index, and EQ Health Index were obtained at 3, 6, and 12 months postoperatively.\u003csup\u003e23,24\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eClinical outcomes were measured.\u0026nbsp;Stair climbing was scored on a 5 point scale modified from the Knee Society Score (Figure 1):\u003csup\u003e25\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eWalking ability was scored on a 6 point scale also modified from the Knee Society Score (figure 2):\u003csup\u003e25\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFunctional outcomes for patients with and without contractures were compared. Fisher\u0026rsquo;s Exact Test was used for categorical variables and Student\u0026rsquo;s t-tests were used for continuous variables.\u003csup\u003e26,27\u003c/sup\u003e Statistical significance was set at p \u0026lt; 0.05.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e372 patients were screened, and 212 did not meet inclusion criteria. 160 patients were recruited and 156 patients were enrolled in the study.\u003csup\u003e21\u003c/sup\u003e 126 patients (55 women and 71 men) aged 16-90 years (average 51 years) were enrolled and had \u0026gt;12 months of radiographic follow up. There was clinical data for 99 patients (44 women, 55 men) at 3 months, 90 patients (41 women, 49 men,) at 6 months and 74 patients (35 women, 39 men) at one year. \u0026nbsp;84 of 126 fractures (66.7%) were type 33-A extraarticular fractures. 42 of 123 (33.3%) were type 33-C1 or 33-C2 with simple articular splits. 33 of 126 fractures (26.2%) were open fractures, all Gustilo type II and type IIIA. The average Injury Severity Score overall was 12.6 (9-43).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe overall rate of documented knee flexion contracture was 16% at 3 months and 14% at one year (so most who developed flexion contracture still it had at one year). Patients did not tend to show improvement between 3 months and one year (p = 0.67).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAt one year patients without knee flexion contractures had significantly better functional outcome scores than those patients with knee flexion contractures as measured by the SMFA (p = 0.038). SMFA scores at one year for patients without a flexion contracture were 22.8 versus 41.8 for patients with a knee flexion contracture (p = 0.038). These results are seen in Table 1. Notably, as the normative values for patients aged 50 years is 13.6 for both the SMFA and the Bother Index, many patients, irrespective of their knee extension, remained substantially affected by their injury at one year.\u003csup\u003e28\u003c/sup\u003e Furthermore, patients without a flexion contracture showed steady improvement in their SMFA score at each follow up visit while patients with flexion contracture did not show improvement in their SMFA score over time. At 3, 6, and 12 months the SMFA scores for patients without contracture were 40.3, 28.6 and 22.8, and the SMFA scores for those patients with a flexion contracture were 44.1, 55.4, 41.8 (Figure 3). Conversely, the Bother Index (p = 0.29) and EQ Health State (p = 0.12) scores did not demonstrate a difference between patients with or without a flexion contracture at any time point (Table 1 and Figure 3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1: Functional Outcome at One Year\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLooking at functional ability, at one year patients without knee flexion contracture also did better than patients with knee flexion contracture. Specifically, patients with full knee extension demonstrated improved walking ability compared to those who had a flexion contracture (2.63 versus 4.1, p = 0.008). The typical patient at one year with full knee extension could walk more than ten blocks and the typical patient with a flexion contracture could walk fewer than five blocks (Table 1). Similarly, patients with full knee extension had better stair climbing ability than those who had a flexion contracture (2.41 versus 3.40, p = 0.02). On average, patients with full knee extension could climb stairs independently and patients with a flexion contracture required the use of a hand rail (Table 1).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOf the factors evaluated, only an older age was associated with the development of a knee flexion contracture. At no time point was the type of fixation (LLP v RIMN), the patient\u0026rsquo;s gender, or whether the fracture was open or closed associated with the development of a flexion contracture. Patients without knee flexion contracture averaged 52 years of age, while patients with knee flexion contracture averaged 65 years of age, which was statistically different (p=0.01). The rate of flexion contracture at one year was 17.1% in women versus 10.5% in men (p=0.51). The rate of flexion contracture at one year was 11.8% in the RIMN group versus 16.2% for the LLP group (p=0.74). The rate of flexion contracture at one year was in patients with open fractures 23.5% versus 11.1% for closed fractures (p=0.24). These results may be seen in Table 2.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eWhile there is a paucity of data on the functional outcomes of patients with flexion contractures after distal femur fracture, there have been a significant number of studies reporting on patients with knee flexion contracture after procedures like total knee arthroplasty and ACL reconstruction (as well basic science/gait analysis reports).\u003csup\u003e4,8,9\u003c/sup\u003e Patients with knee flexion contractures have been shown to walk more slowly and require both more energy and more force to maintain their knees in an extended position.\u003csup\u003e14\u003c/sup\u003e While some patients respond well to physical therapy and other modalities (e.g. manipulation under anesthesia, or operative treatment, some flexion contractures that are present at 3 months post operatively become permanent.\u003csup\u003e8,20\u003c/sup\u003e Older patients seem to be at increased risk both for the development of a flexion contracture and for that contracture to become permanent.\u003csup\u003e8,17,19,20\u003c/sup\u003e In one study, each decade of life increased the likelihood of a flexion contracture of greater than 10 degrees by 35%.\u003csup\u003e8\u003c/sup\u003e In terms of functional scoring, Ritter showed that those patients with \u0026gt;10\u0026deg; of flexion contracture after TKA had significantly lower Knee Society pain and function scores when compared to patients achieving full extension.\u003csup\u003e8\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSimilarly, this study found that patients with distal femur fractures who failed to recover full knee extension and developed flexion contractures also did more poorly than patients who regained full extension. \u0026nbsp;Specifically, patients with knee flexion contractures had worse functional outcome scoring, at least in terms of the SMFA, and they showed no improvement from 3 months to 1 year. Additionally, those with a contracture at 3 months tended to have a contracture at 1 year. Similarly, patients with knee flexion contractures did worse clinically, in terms of walking ability and stair climbing ability. Finally, with the number of patients in this study, while gender, implant chosen and whether the fracture was originally open (an indicator of higher energy mechanism) did not correlate with the development of a flexion contracture, increasing age did correlate with the development of a knee flexion contracture, similar to reports in the arthroplasty literature.\u003c/p\u003e\n\u003cp\u003eLimitations of this study include the accuracy of measurement by using a goniometer, which has been noted to have some degree of inaccuracy.\u003csup\u003e29\u003c/sup\u003e To mitigate this effect a 10 degree cutoff for flexion contracture was chosen rather than 5 degrees, to favor investigating contractures that would be more likely to be clinically relevant. Certainly one could investigate patients with more subtle contractures to see whether those also decrease patient function, however, in this study these patients would be included in the \u0026ldquo;normal\u0026rdquo; group, further demonstrating the dysfunction of the contracture group. Another limitation is that while the benefits of a multicenter study include the potential to extrapolate a conclusion across a broader population, there is the inherent potential for heterogeneity (e.g. we delegated measurements of contracture to the individual local investigators). That said, these were all attending orthopaedic trauma surgeons who were the local primary investigators for the study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn conclusion, patients with distal femur fractures who develop flexion contractures postoperatively struggle to regain function and do worse both clinically and functionally than patients who regain full extension. Similar to total knee arthroplasty patients, older patients with distal femur fractures also seem to be at greater risk for flexion contracture than younger patients. Given that those with contracture at 3 months tended to maintain this contracture at one year post operatively, a focus on early mobility, with an emphasis placed on regaining full extension, avoiding a knee flexion contracture, rather than hoping to treat and overcome one, is particularly important in this patient group.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003ePT3, CC, CB, KE, CJ, RO, WR designed studyRD , MC, and PT3 wrote and revised manuscriptAll authors except AZ and MC were primary investigators at their institutions and directed the acquisition of dataAZ was nonetheless reposnsible for data analysis and directed the acquisition at his institutionAll authors reviewed and edited manuscriptAll authors approve submitted work\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eData for this project, including all data for tables \u0026amp; figures is available upon request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eNasr AM, McLeod I, Sabboubeh A, Maffulli N. 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J Arthroplasty. 2011;34:855-9.\u003c/li\u003e\n \u003cli\u003eDunbar RP, Egol KA, Jones CB, Ertl JP, Mullis B, Perez E, Collinge CA, Ostrum R, Humphrey C, Gardner MJ, Ricci WM, Phieffer LS, Teague D, Ertl W, Born CT, Zonno A, Siegel J, Sagi HC, Pollak A, Schmidt AH, Templeman D, Sems A, Freiss DM, Pape HC, Krieg JC, Tornetta P III. Locked lateral plating vs. retrograde nailing for distal femur fractures: A multicenter randomized trial. J Orthop Trauma. 2023;37(2):70-6.\u003c/li\u003e\n \u003cli\u003eMeinberg EG, Agel J, Roberts CS, et al. Fracture and Dislocation Classification Compendium - 2018. J Orthop Trauma. 2018;32 Supplement 1 pp: S1-S170.\u003c/li\u003e\n \u003cli\u003eSwiontkowski MF, Engelberg R, Martin DP et al. Short musculoskeletal function assessment questionnaire: validity, reliability, and responsiveness. J Bone Joint Surg Am. 1999;81(9):1245-60.\u003c/li\u003e\n \u003cli\u003eEuroQoL Group. EuroQoL \u0026ndash; A new facility for the measurement of health-related quality of life. Health Policy. 1990;16:199-208.\u003c/li\u003e\n \u003cli\u003eInsall JN, Dorr LD, Scott RD, et al. Rationale of the Knee Society clinical rating system. Clin Orthop Rel Res. 1989;248:13-4.\u003c/li\u003e\n \u003cli\u003eFisher RA. On the interpretation of X2 from contingency tables and the calculation of P. J Roy Stat Soc. 1922;85(1):87-94.\u003c/li\u003e\n \u003cli\u003eStudent (Gosset WS). The probable error of a mean. Biometrika. 1908;6(1):1-25.\u003c/li\u003e\n \u003cli\u003eEngelberg R, Martin DP, Agel J, Swiontkowski MF. Musculoskeletal Function Assessment: Reference values for patient and non-patient samples. J Orthop Res 1999;17:101-9.\u003c/li\u003e\n \u003cli\u003eLenssen AF, van Dam EM, Crijns YH, Verhey M, Geesink RJ, van den Brandt PA, de Bie RA. Reproducibility of goniometric measurement of the knee in the in- hospital phase following total knee arthroplasty. BMC Musculoskelet Disord 2007;8:83:1-7.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable 1 and 2 are available in the Supplementary Files section.\u003c/p\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":"Distal Femur fracture, Knee flexion contracture, patient reported outcome score","lastPublishedDoi":"10.21203/rs.3.rs-7223366/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7223366/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eOBJECTIVES:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e·\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; To determine if patients with knee flexion contracture after distal femur fracture have poorer outcomes than patients who regain full knee extension.\u003c/p\u003e\n\u003cp\u003e·\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; To determine if factors such as patient age, gender, open fracture or implant used favors knee flexion contracture.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMETHODS:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eDesign:\u0026nbsp;\u003c/strong\u003e\u003c/em\u003eProspective, multicenter trial\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eSetting:\u0026nbsp;\u003c/strong\u003e\u003c/em\u003eTwenty academic level I trauma centers\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003ePatient Selection Criteria:\u0026nbsp;\u003c/strong\u003e\u003c/em\u003ePatients with a distal femur fracture. Patients were evaluated for knee flexion contracture at 3, 6 and 12 months post-operatively.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eOutcome Measures and Comparisons:\u0026nbsp;\u003c/strong\u003e\u003c/em\u003eSMFA, Bother Index and EQ Health Index scores were recorded. Walking and stair climbing ability were assessed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRESULTS:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e·\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; 126 patients had radiographic follow up for 12 months. There was clinical follow-up for 99 patients at 3 months, 90 patients at 6 months and 74 pts at 12 months.\u003c/p\u003e\n\u003cp\u003e·\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Patients with full knee extension had better SMFA scores at 12 months than patients with knee flexion contracture (p = 0.308).\u003c/p\u003e\n\u003cp\u003e·\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Bother Index (p = 0.29) and EQ\u003csub\u003eHealth State\u003c/sub\u003e (p = 0.12) scores did not demonstrate a difference between patients with or without knee flexion contracture at any time point.\u003c/p\u003e\n\u003cp\u003e·\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Patients with full knee extension had improved walking ability compared to patients with flexion contracture (p = 0.008). Patients with full knee extension had better stair climbing ability than patients with flexion contracture (p = 0.02).\u003c/p\u003e\n\u003cp\u003e·\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Only older patient age showed a difference in likelihood of flexion contracture (p = 0.01) The rates of flexion contracture in women versus men (p = 0.51), RIMN versus LLP (p = 0.74) and open versus closed fracture (p = 0.24) were not statistically different.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCONCLUSIONS:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e·\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Patients with knee flexion contractures after distal femur fracture do worse than patients who regain full extension.\u003c/p\u003e\n\u003cp\u003e·\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Older patients with distal femur fractures are at greater risk for knee flexion contracture.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLEVEL OF EVIDENCE: \u003c/strong\u003eLevel I\u003c/p\u003e","manuscriptTitle":"The Effect of Knee Flexion Contracture on Patient Reported Outcome Measures after Distal Femur Fractures (OTA/AO Type 33):A Multi-Center Prospective Evaluation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-12 14:42:26","doi":"10.21203/rs.3.rs-7223366/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":"779c39a9-55b6-48f1-8720-ce65b5e85038","owner":[],"postedDate":"September 12th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-02-24T01:39:49+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-12 14:42:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7223366","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7223366","identity":"rs-7223366","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}