Comparative outcomes of total knee arthroplasty in patients with posttraumatic versus primary knee osteoarthritis

Comparative outcomes of total knee arthroplasty in patients with posttraumatic versus primary knee osteoarthritis | 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 Comparative outcomes of total knee arthroplasty in patients with posttraumatic versus primary knee osteoarthritis Stefanie Waldburger, Vilijam Zdravkovic, Andreas Ladurner, David Hamilton, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8668688/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 Posttraumatic osteoarthritis (ptOA) of the knee accounts for 12.5% of all total knee arthroplasties (TKA) and is associated with significantly higher complication and revision rates than in TKA for primary osteoarthritis (pOA). However, the impact of ptOA on patient-reported outcomes is less clear. The purpose of this study is to analyse longitudinal clinical and patient-reported outcomes in these patient groups. Methods A retrospective analysis of prospectively collected data from an institutional database was performed (time frame 2006–2023). Patients with a history of intraarticular femoral or tibial fractures (ptOA) were identified, and propensity score matched (1:3 ratio) for age, sex and body mass index (BMI) to a comparable cohort receiving TKA for pOA. Outcomes at one year were assessed using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Forgotten Joint Score-12 (FJS-12), EuroQo-5D (EQ-5D), range of motion (ROM) and overall patient satisfaction. Results 72 patients with ptOA were compared to 216 matched pOA patients. There were no statistically significant differences in WOMAC (19.95 vs 15.61; p = 0.15) or EQ-5D (0.75 vs 0.80; p = 0.14) between the two groups at 1-year follow-up. FJS-12 showed significantly inferior result 1-year postoperatively in the ptOA group (56.4 vs 71.3; p = 0.02). Overall patient satisfaction (72.4 vs 89.6%; p = 0.001) and pre- and post-operative ROM (p < 0.001) were also significantly worse in the ptOA group. Conclusions There was no difference in traditional joint-specific or general heatlh scores (WOMAC or EQ5D scores) between patients with primary or posttraumatic OA. However, patients undergoing TKA for ptOA reported poorer higher-level outcomes (FJS-12 scores), poorer satisfaction rates and poorer knee flexion at 1-year. Trial Registration: Ethics committee of Eastern Switzerland EKOS; Project-ID 2023 − 00813, Registration date 03.05.2023 posttraumatic knee osteoarthritis TKA patient-reported outcome Forgotten Joint Score-12 PROM Figures Figure 1 Figure 2 Background Total knee arthroplasty (TKA) is the gold-standard treatment for symptomatic, end-stage knee osteoarthritis, offering high patient satisfaction and low complication and revision rates [ 1 ], [ 2 ]. While primary osteoarthritis (pOA) is the most common indication for TKA, posttraumatic osteoarthritis (ptOA) accounts for up to 12.5% of cases [ 3 ]. Compared to pOA, TKA for ptOA is associated with higher complication and revision rates. Superficial and deep infections occur more frequently (0.34% vs. 0.15%, and 0.47% vs. 0.27%, respectively) [ 4 ], and patients with ptOA tend to have worse range of motion and a higher incidence of fixed flexion contractures pre- and postoperatively [ 5 ]; [ 6 ]. Five-year revision rates are also elevated in ptOA (6–21%) compared to pOA (2.5–7.9%) [ 7 ]; [ 8 ];[ 1 ]; [ 2 ]). These poorer outcomes are likely due to the increased surgical complexity in ptOA, including challenges such as scar tissue, contractures, malalignment, bone defects, retained hardware, or low-grade infections [ 9 ]. While complication and revision rates are important aspects of outcome, patient-reported outcomes such as pain, function, daily symptom burden and satisfaction are equally critical. Among the well established patient-reported outcome measures (PROMs), the Forgotten Joint Score-12 (FJS-12) effectively measures joint awareness with minimal ceiling effects [ 10 ]; [ 11 ]. The Western Ontario and McMaster University Osteoarthritis Index (WOMAC) is widely used to assess postoperative function [ 12 ]; [ 13 ], and the EQ-5D, though less sensitive, provides a general health assessment post-TKA [ 12 ]. Despite consistent reports of higher complication and revision rates in ptOA, findings on PROMs are mixed. Some studies report worse outcomes in ptOA [ 5 ], while others find no significant difference compared to pOA [ 14 ]; [ 6 ]. Comparative data on patient satisfaction remain scarce [ 15 ]. Moreover, the well reported ceiling effects of some PROMs may obscure subtle differences in high-functioning patients [ 16 ]; [ 17 ]; [ 18 ]. This study aims to compare clinical and patient-reported outcomes, as well as longitudinal improvements, in patients undergoing TKA for ptOA versus pOA. We hypothesize that there is no significant difference in postoperative outcomes between these groups. Methods Study Design: A retrospective analysis was performed on prospectively collected data from a single large teaching hospital in Switzerland. The institutional database prospectively collects patient- and surgery-related information of all patients undergoing TKA. Each dataset contains patient demographics, medical history including prior surgery around the affected knee, surgery related data (indication, approach, type of implant, degree of constraint), range of motion (ROM) and a standardized set of PROMs. FJS-12, WOMAC, EQ-5D, and patient satisfaction metrics were available for analysis. Data acquisition was performed and documented by a trained study physiotherapist. Clinical parameters and PROMs were recorded pre-operatively and at 1-year postoperative follow-up. Informed consent was obtained from all patients prior to data collection for their anonymous data to be collected and included in ethically approved research studies. The study was approved by the local institutional ethics committee (ethics committee of Eastern Switzerland EKOS; Project-ID 2023 − 00813) in accordance with the Declaration of Helsinki. Eligibility criteria All patients registered in our hospital database for receiving primary TKA between March 2006 and May 2023 were screened. TKAs for ptOA and pOA were identified, and accuracy of this group allocation was verified through medical chart review. All ptOA cases underwent further review of their x-rays and surgery reports. Patients with previous intraarticular distal femur or proximal tibial fractures were included, and further grouped according to fracture type into unicondylar or bicondylar fractures (distal femur) or lateral, medial und bicondylar fractures (proximal tibia). Patients with (isolated) patellar fractures, traumatic meniscal tears or ligament injuries, or those with incomplete medical charts or a follow-up of < 1 year were excluded Propensity score matching for pre-operative baseline data (sex, age, BMI) was performed in order to obtain a matched cohort of patients undergoing TKA for pOA. Matching was performed at a 1:3 ratio (ptOA : pOA) from 2126 patients with pOA (see Fig. 1 ). Outcome measures Primary outcomes were FJS-12, WOMAC, EQ-5D and overall patient satisfaction (measured on a 5-point Likert scale, graded: very dissatisfied - dissatisfied – neutral - satisfied – very satisfied) at 1-year follow-up. Secondary outcomes were improvement of PROM over time (pre-op vs. 1-year follow-up) and postoperative knee flexion (measured with a standard goniometer) at 1 year. The FJS-12 was first described in 2012 as a joint specific PROM. The score assesses joint awareness in hips and knees in daily living. It consists of 12 equally weighted questions and uses a 5-point Likert response format. The raw score is transformed to range from 0 to 100 points. High scores indicate good outcome, i.e. a high degree of forgetting the joint in everyday life. The FJS-12 has been found to have a low ceiling effect one and two years after TKA [ 10 ], [ 11 ], [ 16 ]. The WOMAC score is a widely used, self-report outcome measure consisting of 24 questions covering three separate dimensions: pain (5 questions), stiffness (2 questions) and function (17 questions). The score is linearly converted to a range from 0 to 100 points, and lower scores translate into better outcome. This score has been extensively tested for validity, reliability, feasibility and responsiveness[ 19 ], [ 20 ]. However, it reportedly has limited discriminatory power, i.e. a ceiling effect in well performing patients following TKA [ 21 ], [ 22 ]. EQ-5D was employed to measure self-reported general health status, using a standardised 5-item questionnaire [ 23 ]. It covers self-care, mobility, depression/anxiety, pain and usual activities. It is internationally one of the most frequently used measurement of quality of life in health economics. The utility measure ranges from 0 to 1, the latter indicating perfect health. Statistical analysis All statistics were conducted using R (R: A language and environment for statistical computing: R Foundation for Statistical Computing, Vienna, Austria). Descriptive statistics includes means, standard deviations, 95% confidence intervals, ranges and proportions. Propensity score matching was applied in R to compensate for potential baseline differences in sex, age and BMI. T-test and Chi-square test were employed to investigate the changes in FJS-12, WOMAC, EQ-5D, ROM and patient satisfaction. Wilcoxon and Fisher exact test were applied where alternatively appropriate. The confidence level for rejecting the null hypothesis was set at 95% (p-value < 0.05). Results A total of 288 cases were analysed. A standard parapatellar antero-medial approach was used for most procedures, while an anterolateral approach combined with tibial tuberosity osteotomy was performed in 18.1% of cases. Overall twelve orthopaedic surgeons performed the 288 surgeries, four surgeons performed the majority of cases (71.9%). All TKAs were implanted using cemented fixation, with a tourniquet applied prior to cement application. Throughout the study period, computer navigation was employed for all unconstrained and semi-constrained TKAs, whereas constrained implants were operated without computer navigation using conventional instrumentation. The postoperative protocol included standardized inpatient and outpatient physiotherapy regimens over a three-month period, which were identical for both groups. Patient and surgery related characteristics are outlined in Table 1 . Propensity matching led to perfectly balanced baseline characteristics for both cohorts. Interestingly, this also resulted in equal WOMAC at baseline in the ptOA and pOA group (50.99 vs 51.1; p = 0.97). Patients were 61 years old on average, and 52% were female. The vast majority of patients received unconstrained implants, while semi-constrained and constrained implants were more commonly used in the ptOA cohort. Differences in primary and secondary outcome parameters are outlined in Table 2 and Fig. 2 . The ptOA cohort showed significantly lower FJS-12 scores (i.e. higher joint awareness) at 1-year follow-up when compared to the pOA group (56.4 vs 71.3; p = 0.016) despite the smaller number of completed FJS-12 questionnaires. Note that the cross-sectional mean values at baseline and 1-year post-op do not match with the improvement as a difference, as improvement was calculated for each patient with linked data and then presented as means of improvement. No significant difference in postoperative WOMAC or EQ-5D was detected between the groups. The postoperative improvement of all PROMs was not significantly different between the ptOA and pOA cohort. Overall patient satisfaction at 1-year follow-up was lower in the ptOA group. Here, 72.4% of patients were “satisfied” with the result, while this applied to 89.6% of patients in the pOA cohort (p = 0.001). Knee flexion was significantly lower in the ptOA group, both pre- and postoperatively (p < 0.001). Subgroup analyses for different types of implant constraint or various fracture types were not possible due to insufficient number of patients for small subgroups. Table 1 Patient characteristics ptOA cohort pOA cohort p-value N 72 216 Sex Female (N; %) Male (N;%) 38 (52.8%) 34 (47.2%) 113 (52.3%) 103 (47.7%) 0.95 Mean Age (years) 60.8 61.2 0.82 Mean BMI (kg/m 2 ) 27.2 27.4 0.83 Type of implant Unconstrained * Semi-constrained ** Constrained *** 60 (83.3%) 5 (6.9%) 7 (9.7%) 202 (93.5%) 3 (1.4%) 11 (5.1%) Fracture pattern (N; %) Proximal tibia fractures Unicondylar lateral Unicondylar medial Bicondylar Not specified / unknown Distal femur fractures Unicondylar Bicondylar Not specified / unknown Proximal tibia and distal femur Unknown fracture type 54 (75%) 20 (37%) 6 (11.1%) 22 (40.7%) 6 (11.1%) 13 (18.1%) 5 (38.5%) 5 (38.5%) 3 (23.1%) 3 (4.2%) 2 (2.8%) NA NA Tibial tubercle osteotomy (N;%) 22 (30.6%) 30 (13.9%) Concomitant interventions (N; %) Hardware removal 31 (43.1%) NA NA *DePuy LCS complete (2006–2015) and DePuy Attune (2015–2023) **DePuy LCS Revision (2006–2015) and DePuy Attune Revision (2015–2023) *** Smith& Nephew RT solution & modular (2006–2023) Table 2 Results of primary and secondary outcome parameters ptOA cohort (N = 72) pOA cohort (N = 216) p-value FJS-12 (mean ± SD, range) - Pre-operative - 1-year follow-up - Improvement 16.62 (18.85) 56.41 (37.93) 46.67 (33.42) 12.78 (12.39) 71.28 (34.71) 60.34 (32.68) 0.30 0.02 0.10 WOMAC (mean ± SD, range) - Pre-operative - 1-year follow-up - Improvement 50.99 (18.86) 19.95 (20.71) 29.61 (20.26) 51.10 (19.13) 15.61 (17.12) 34.56 (20.00) 0.97 0.15 0.12 EQ-5D (mean ± SD, range) - Pre-operative - 1-year follow-up - Improvement 0.50 (0.30) 0.75 (0.26) 0.26 0.47 (0.31) 0.80 (0.26) 0.32 0.52 0.14 0.17 Patient satisfaction “satisfied” (%) - 1-year follow-up 72.4% 89.6% < 0.01 ROM (flexion ( degree); mean ±SD, range ) - Pre-operative - 1-year follow-up - Improvement 104.8 (23.1) 105.6 (19.4) 0.5 (18.8) 115.9 (17.4) 116.6 (12.6) -0.3 (17.8) < 0.01 < 0.01 0.78 Discussion This study found no significant differences in traditional PROMs with limited responsiveness (EQ-5D and WOMAC) between patients undergoing TKA for ptOA versus pOA. However, the FJS-12 revealed significantly worse outcomes in the ptOA group, indicating higher joint awareness after a previous fracture. The 14.9-point difference exceeds the minimal clinically important difference (MCID) reported in the literature ([ 24 ], [ 25 ], [ 26 ] suggesting clinical relevance. Additionally, ptOA patients showed reduced knee flexion (pre- and post-op) and lower satisfaction rates at 1-year follow-up. Previous studies have reported mixed findings regarding PROMs in ptOA. Lizauer, Lunebourg and Lützner found no differences in KSS or WOMAC scores at 1- to 5-year follow-ups. Similarly, Khoshbin reported comparable KOOS, LEAS (Lower Extremity Activity Score), and SF-12 scores at 2 years post-TKA. However, these instruments, particularly WOMAC and KSS, are known to have limited responsiveness and pronounced ceiling effects, which may obscure outcome differences [ 16 ], [ 28 ], [ 29 ]. Thompson noted that the FJS-12 had a wider score distribution and greater sensitivity to group differences than WOMAC or KOOS, a finding supported by several other studies [ 18 ]. These characteristics likely explain why our study, using FJS-12, identified outcome disparities missed by prior research using older tools. Our satisfaction rates further support these findings: 89.6% in the pOA group versus 72.4% in the ptOA group. These align with existing literature, where satisfaction following TKA generally ranges from 85% to 90% [ 30 ]. Scott et al. also reported lower satisfaction in ptOA (78%) compared to pOA (86%), though their results did not reach statistical significance. The reduced satisfaction observed in our ptOA cohort may be attributed to impaired knee flexion – at baseline and at 1-year follow-up and greater joint awareness, both indicative of poorer physical outcomes. Lunebourg et al. and Lützner et al. similarly reported reduced ROM in ptOA patients. It is also possible that an expectation–outcome mismatch contributed to lower satisfaction in the ptOA group, as shown to impact patient-reported satisfaction in arthroplasty [ 31 ]. While we were unable to measure patient expectations directly, this remains a potential explanatory factor warranting further research. This study has several limitations. First, its retrospective design and the relatively small number of patients with posttraumatic osteoarthritis (ptOA) may limit generalizability. We did not have complete longitudinal PROM data as reported in Fig. 2 . This predominantly affects FJS-12 data, as implementation of pre-op FJS-12 data collection in our institutional TKA register started in 2009 whereas post-op FJS-12 data collection only started in 2016 – in all TKA patients – primary and posttraumatic. However, data collection was conducted prospectively, and thorough review of medical records and radiographs ensured data accuracy, thereby reducing the potential for bias commonly associated with retrospective analyses. To improve comparability between groups, propensity score matching (1:3 ratio) was used to create homogeneous cohorts. This resulted in well-balanced groups with matched age, sex, and BMI, as well as perfectly comparable baseline WOMAC scores. Well validated PROMs, including the FJS-12, were employed. Notably, this is the first study to use the FJS-12 in this context, and it actually proved sensitive in distinguishing outcomes between the ptOA and primary OA (pOA) groups from the patient’s perspective. Another limitation is the absence of data on complications and revision procedures, which are well known to occur more frequently in ptOA from literature – but these aspects of outcome were not the focus of this study. Conclusion Patients undergoing TKA for posttraumatic OA report the same outcomes as matched patients undergoing TKA for primary OA when assessed using traditional PROM tools. However, joint awareness, knee flexion and patient satisfaction are all significantly lower at 1-year in patients with posttraumatic OA, which is of relevance when counselling patients with ptOA preoperatively in order to optimize expectation management. Declarations Clinical trial number Not applicable Ethical Approval This study has been registered and approved by the ethics committee of Eastern Switzerland (EKOS; Project-ID: EKOS 2023-00813) in accordance with the Declaration of Helsinki. Consent to participate All patients provided informed consent to take part in the study. Consent for publication Not applicable Availability of data and materials The datasets generated and analysed during the current study are not publicly available as access to the relevant institutional database is restricted to the public, but data are available from the corresponding author on reasonable request. Competing interests Giesinger K is a copyright holder of the FJS-12. All other authors declare that they have no competing interests. Funding No direct or indirect support for this project was received. Authors’ Contributions SW and KG conceived the study. SW, AL, DFH and KG drafted the manuscript. SW, KG and VZ were involved in analysis and interpretation of data. SW, KG, VZ and AL provided the figures and tables. All authors edited, read and approved the final manuscript. References Brittain R et al. NJR statistical analysis, support and associated services National Joint Registry | 19th Annual Report. [Online]. Available: www.njrcentre.org.uk. Charette RS, Sloan M, DeAngelis RD, Lee GC. Higher Rate of Early Revision Following Primary Total Knee Arthroplasty in Patients Under Age 55: A Cautionary Tale, Journal of Arthroplasty, vol. 34, no. 12, pp. 2918–2924, Dec. 2019, 10.1016/j.arth.2019.06.060 Matziolis G, Windisch C. Die posttraumatische Arthrose - eine Herausforderung? Z Orthop Unfall. 2014;152(5):510–5. 10.1055/s-0034-1383092 . Saleh H, Yu S, Vigdorchik J, Schwarzkopf R. Total knee arthroplasty for treatment of post-traumatic arthritis: Systematic review. World J Orthop. Sep. 2016;7(9):584–91. 10.5312/wjo.v7.i9.584 . Lunebourg A, Parratte S, Gay A, Ollivier M, Garcia-Parra K, Argenson JN. Lower function, quality of life, and survival rate after total knee arthroplasty for posttraumatic arthritis than for primary arthritis, Acta Orthop., vol. 86, no. 2, pp. 189–194, Apr. 2015, 10.3109/17453674.2014.979723 Lützner C, Postler A, Beyer F, Lange T, Riedel R, Lützner J. Total knee arthroplasty in post-traumatic osteoarthritis is more challenging, but results in similar patient satisfaction – An analysis of 1646 cases, Knee, vol. 39, pp. 116–123, Dec. 2022, 10.1016/j.knee.2021.12.005 Houdek MT, Watts CD, Shannon SF, Wagner ER, Sems SA, Sierra RJ. Posttraumatic Total Knee Arthroplasty Continues to Have Worse Outcome Than Total Knee Arthroplasty for Osteoarthritis. J Arthroplasty. Jan. 2016;31(1):118–23. 10.1016/j.arth.2015.07.022 . Weiss NG, Parvizi J, Trousdale RT, Bryce RD, Lewallen DG. Total Knee Arthroplasty in Patients with a Prior Fracture of the Tibial Plateau, 2003. Dexel J, Beyer F, Lützner C, Kleber C, Lützner J. TKA for posttraumatic osteoarthritis is more complex and needs more surgical resources. Orthopedics. May 2016;39(3):S36–40. 10.3928/01477447-20160509-11 . Behrend H, Giesinger K, Giesinger JM, Kuster MS. The ‘Forgotten Joint’ as the Ultimate Goal in Joint Arthroplasty. Validation of a New Patient-Reported Outcome Measure. J Arthroplasty. 2012;27(3). 10.1016/j.arth.2011.06.035 . Lee QJ, Chang WYE, Wong YC. Forgotten Joint Score for early outcome assessment after total knee arthroplasty: Is it really useful? Knee Surg Relat Res. Dec. 2020;32(1). 10.1186/s43019-020-00049-0 . Brazier JE, Harper R, Munro J, Walters SJ. and M. L. Snaith1, Generic and condition-specific outcome measures for people with osteoarthritis of the knee, 1999. Kreibich DN et al. What Is the Best Way of Assessing Outcome After Total Knee Replacement? Lippincott-Raven Publishers, 1996. [Online]. Available: http://journals.lww.com/clinorthop Lizaur-Utrilla A, Collados-Maestre I, Miralles-Muñoz FA, Lopez-Prats FA. Total Knee Arthroplasty for Osteoarthritis Secondary to Fracture of the Tibial Plateau. A Prospective Matched Cohort Study, Journal of Arthroplasty, vol. 30, no. 8, pp. 1328–1332, Aug. 2015, 10.1016/j.arth.2015.02.032 Scott CEH, Davidson E, Macdonald DJ, White TO, Keating JF. Total knee arthroplasty following tibial plateau fracture A MATCHED COHORT STUDY, 10.1302/0301-620X.97B4 Giesinger K, Hamilton DF, Jost B, Holzner B, Giesinger JM. Comparative responsiveness of outcome measures for total knee arthroplasty, Osteoarthritis Cartilage, vol. 22, no. 2, pp. 184–189, Feb. 2014, 10.1016/j.joca.2013.11.001 Kuhns BD, Harris WT, Domb BG. Low Ceiling Effects of the Forgotten Joint Score Compared With Legacy Measures After Joint-Preserving Procedures: A Systematic Review, Arthroscopy: The Journal of Arthroscopic & Related Surgery, vol. 39, no. 9, pp. 2086–2095, Sep. 2023, 10.1016/j.arthro.2023.01.107 Ladurner A, Giesinger K, Zdravkovic V, Behrend H. The Forgotten Joint Score-12 as a valuable patient-reported outcome measure for patients after first-time patellar dislocation, Knee, vol. 27, no. 2, pp. 406–413, Mar. 2020, 10.1016/j.knee.2019.12.004 Angst F, Andr´ A, Aeschlimann A, Stucki G. Smallest Detectable and Minimal Clinically Important Differences of Rehabilitation Intervention With Their Implications for Required Sample Sizes Using WOMAC and SF-36 Quality of Life Measurement Instruments in Patients With Osteoarthritis of the Lower Extremities, 2001. Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW. Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee., J. Rheumatol., vol. 15, no. 12, pp. 1833–40, Dec. 1988. Eckhard L, et al. The ceiling effects of patient reported outcome measures for total knee arthroplasty. Orthop Traumatology: Surg Res. May 2021;107(3). 10.1016/j.otsr.2020.102758 . Sansone V, et al. Translation, cross-cultural adaptation, and validation of the Italian language Forgotten Joint Score-12 (FJS-12) as an outcome measure for total knee arthroplasty in an Italian population. BMC Musculoskelet Disord. Jan. 2020;21(1). 10.1186/s12891-019-2985-2 . EuroQol Group. EuroQol–a new facility for the measurement of health-related quality of life. Health Policy. Dec. 1990;16(3):199–208. 10.1016/0168-8510(90)90421-9 . Clement ND, Scott CEH, Hamilton DF, MacDonald D, Howie CR. Meaningful values in the Forgotten Joint Score after total knee arthroplasty. Bone Joint J. May 2021;103–B:846–54. 10.1302/0301-620X.103B5.BJJ-2020-0396.R1 . Holtz N, Hamilton DF, Giesinger JM, Jost B, Giesinger K. Minimal important differences for the WOMAC osteoarthritis index and the Forgotten Joint Score-12 in total knee arthroplasty patients. BMC Musculoskelet Disord. Jun. 2020;21(1). 10.1186/s12891-020-03415-x . Ingelsrud LH, Roos EM, Terluin B, Gromov K, Husted H, Troelsen A. Minimal important change values for the Oxford Knee Score and the Forgotten Joint Score at 1 year after total knee replacement, Acta Orthop., vol. 89, no. 5, pp. 541–547, Sep. 2018, 10.1080/17453674.2018.1480739 Khoshbin A, et al. Patient-Reported Outcome Measures of Total Knee Arthroplasties for Post-Traumatic Arthritis versus Osteoarthritis: A Short-Term (5- to 10-year) Retrospective Matched Cohort Study. J Arthroplasty. May 2019;34(5):872–6. 10.1016/j.arth.2019.01.022 . Thompson SM, Salmon LJ, Webb JM, Pinczewski LA, Roe JP. Construct Validity and Test Re-Test Reliability of the Forgotten Joint Score, Journal of Arthroplasty, vol. 30, no. 11, pp. 1902–1905, Nov. 2015, 10.1016/j.arth.2015.05.001 Ko Y et al. Nov., Comparison of the responsiveness of the SF-36, the Oxford Knee Score, and the Knee Society Clinical Rating System in patients undergoing total knee replacement, Quality of Life Research, vol. 22, no. 9, pp. 2455–2459, 2013, 10.1007/s11136-013-0376-y Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KDJ. Patient satisfaction after total knee arthroplasty: Who is satisfied and who is not? in Clinical Orthopaedics and Related Research, Springer New York, 2010, pp. 57–63. 10.1007/s11999-009-1119-9 Neuprez A, et al. Patients’ Expectations Impact Their Satisfaction following Total Hip or Knee Arthroplasty. PLoS ONE. Dec. 2016;11(12):e0167911. 10.1371/journal.pone.0167911 . Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8668688","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":595211666,"identity":"cc5fc82a-3180-43ec-9b00-d9f823d2832a","order_by":0,"name":"Stefanie Waldburger","email":"","orcid":"","institution":"Kantonsspital St. Gallen","correspondingAuthor":false,"prefix":"","firstName":"Stefanie","middleName":"","lastName":"Waldburger","suffix":""},{"id":595211667,"identity":"8c49541c-7d6b-4fdb-ad14-8dd958a64f1a","order_by":1,"name":"Vilijam Zdravkovic","email":"","orcid":"","institution":"Kantonsspital St. Gallen","correspondingAuthor":false,"prefix":"","firstName":"Vilijam","middleName":"","lastName":"Zdravkovic","suffix":""},{"id":595211668,"identity":"a80da3d3-0487-4c65-b19e-ed0d6691a759","order_by":2,"name":"Andreas Ladurner","email":"","orcid":"","institution":"Triemli Hospital","correspondingAuthor":false,"prefix":"","firstName":"Andreas","middleName":"","lastName":"Ladurner","suffix":""},{"id":595211669,"identity":"559374af-d486-4a33-b994-129960a18e6f","order_by":3,"name":"David Hamilton","email":"","orcid":"","institution":"Glasgow Caledonian University","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"","lastName":"Hamilton","suffix":""},{"id":595211670,"identity":"1da53133-c9d4-4eb3-9d9d-d33e0f5237a2","order_by":4,"name":"Karlmeinrad Giesinger","email":"data:image/png;base64,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","orcid":"","institution":"Kantonsspital St. Gallen","correspondingAuthor":true,"prefix":"","firstName":"Karlmeinrad","middleName":"","lastName":"Giesinger","suffix":""}],"badges":[],"createdAt":"2026-01-22 10:53:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8668688/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8668688/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103216654,"identity":"1fe09a1e-49f3-4983-9877-535f476adce7","added_by":"auto","created_at":"2026-02-23 09:37:24","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":59656,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8668688/v1/549f99737dae3ea2b7c6a1a5.png"},{"id":103216655,"identity":"af5a413a-0d99-4b50-95bb-f5ad7cc37472","added_by":"auto","created_at":"2026-02-23 09:37:24","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":316104,"visible":true,"origin":"","legend":"\u003cp\u003ePROMs pre-and post-op, comparing ptOA and pOA group\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8668688/v1/8985eaf6ff6adfbb0c233e14.jpeg"},{"id":106403187,"identity":"63125ffb-f2b0-43f6-9c96-d14aee1a3836","added_by":"auto","created_at":"2026-04-08 09:13:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":951103,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8668688/v1/019a20f5-380c-4476-99e4-950cd673b505.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparative outcomes of total knee arthroplasty in patients with posttraumatic versus primary knee osteoarthritis","fulltext":[{"header":"Background","content":"\u003cp\u003eTotal knee arthroplasty (TKA) is the gold-standard treatment for symptomatic, end-stage knee osteoarthritis, offering high patient satisfaction and low complication and revision rates [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. While primary osteoarthritis (pOA) is the most common indication for TKA, posttraumatic osteoarthritis (ptOA) accounts for up to 12.5% of cases [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCompared to pOA, TKA for ptOA is associated with higher complication and revision rates. Superficial and deep infections occur more frequently (0.34% vs. 0.15%, and 0.47% vs. 0.27%, respectively) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], and patients with ptOA tend to have worse range of motion and a higher incidence of fixed flexion contractures pre- and postoperatively [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]; [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Five-year revision rates are also elevated in ptOA (6\u0026ndash;21%) compared to pOA (2.5\u0026ndash;7.9%) [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]; [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e];[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]; [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]). These poorer outcomes are likely due to the increased surgical complexity in ptOA, including challenges such as scar tissue, contractures, malalignment, bone defects, retained hardware, or low-grade infections [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWhile complication and revision rates are important aspects of outcome, patient-reported outcomes such as pain, function, daily symptom burden and satisfaction are equally critical. Among the well established patient-reported outcome measures (PROMs), the Forgotten Joint Score-12 (FJS-12) effectively measures joint awareness with minimal ceiling effects [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]; [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The Western Ontario and McMaster University Osteoarthritis Index (WOMAC) is widely used to assess postoperative function [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]; [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], and the EQ-5D, though less sensitive, provides a general health assessment post-TKA [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite consistent reports of higher complication and revision rates in ptOA, findings on PROMs are mixed. Some studies report worse outcomes in ptOA [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], while others find no significant difference compared to pOA [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]; [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Comparative data on patient satisfaction remain scarce [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Moreover, the well reported ceiling effects of some PROMs may obscure subtle differences in high-functioning patients [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]; [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]; [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study aims to compare clinical and patient-reported outcomes, as well as longitudinal improvements, in patients undergoing TKA for ptOA versus pOA. We hypothesize that there is no significant difference in postoperative outcomes between these groups.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design:\u003c/h2\u003e \u003cp\u003eA retrospective analysis was performed on prospectively collected data from a single large teaching hospital in Switzerland. The institutional database prospectively collects patient- and surgery-related information of all patients undergoing TKA. Each dataset contains patient demographics, medical history including prior surgery around the affected knee, surgery related data (indication, approach, type of implant, degree of constraint), range of motion (ROM) and a standardized set of PROMs. FJS-12, WOMAC, EQ-5D, and patient satisfaction metrics were available for analysis. Data acquisition was performed and documented by a trained study physiotherapist. Clinical parameters and PROMs were recorded pre-operatively and at 1-year postoperative follow-up. Informed consent was obtained from all patients prior to data collection for their anonymous data to be collected and included in ethically approved research studies. The study was approved by the local institutional ethics committee (ethics committee of Eastern Switzerland EKOS; Project-ID 2023\u0026thinsp;\u0026minus;\u0026thinsp;00813) in accordance with the Declaration of Helsinki.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eEligibility criteria\u003c/h3\u003e\n\u003cp\u003eAll patients registered in our hospital database for receiving primary TKA between March 2006 and May 2023 were screened. TKAs for ptOA and pOA were identified, and accuracy of this group allocation was verified through medical chart review. All ptOA cases underwent further review of their x-rays and surgery reports. Patients with previous intraarticular distal femur or proximal tibial fractures were included, and further grouped according to fracture type into unicondylar or bicondylar fractures (distal femur) or lateral, medial und bicondylar fractures (proximal tibia). Patients with (isolated) patellar fractures, traumatic meniscal tears or ligament injuries, or those with incomplete medical charts or a follow-up of \u0026lt;\u0026thinsp;1 year were excluded\u003c/p\u003e \u003cp\u003ePropensity score matching for pre-operative baseline data (sex, age, BMI) was performed in order to obtain a matched cohort of patients undergoing TKA for pOA. Matching was performed at a 1:3 ratio (ptOA : pOA) from 2126 patients with pOA (see Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eOutcome measures\u003c/h3\u003e\n\u003cp\u003ePrimary outcomes were FJS-12, WOMAC, EQ-5D and overall patient satisfaction (measured on a 5-point Likert scale, graded: very dissatisfied - dissatisfied \u0026ndash; neutral - satisfied \u0026ndash; very satisfied) at 1-year follow-up. Secondary outcomes were improvement of PROM over time (pre-op vs. 1-year follow-up) and postoperative knee flexion (measured with a standard goniometer) at 1 year.\u003c/p\u003e \u003cp\u003eThe FJS-12 was first described in 2012 as a joint specific PROM. The score assesses joint awareness in hips and knees in daily living. It consists of 12 equally weighted questions and uses a 5-point Likert response format. The raw score is transformed to range from 0 to 100 points. High scores indicate good outcome, i.e. a high degree of forgetting the joint in everyday life. The FJS-12 has been found to have a low ceiling effect one and two years after TKA [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe WOMAC score is a widely used, self-report outcome measure consisting of 24 questions covering three separate dimensions: pain (5 questions), stiffness (2 questions) and function (17 questions). The score is linearly converted to a range from 0 to 100 points, and lower scores translate into better outcome. This score has been extensively tested for validity, reliability, feasibility and responsiveness[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. However, it reportedly has limited discriminatory power, i.e. a ceiling effect in well performing patients following TKA [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEQ-5D was employed to measure self-reported general health status, using a standardised 5-item questionnaire [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. It covers self-care, mobility, depression/anxiety, pain and usual activities. It is internationally one of the most frequently used measurement of quality of life in health economics. The utility measure ranges from 0 to 1, the latter indicating perfect health.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eAll statistics were conducted using R (R: A language and environment for statistical computing: R Foundation for Statistical Computing, Vienna, Austria). Descriptive statistics includes means, standard deviations, 95% confidence intervals, ranges and proportions. Propensity score matching was applied in R to compensate for potential baseline differences in sex, age and BMI. T-test and Chi-square test were employed to investigate the changes in FJS-12, WOMAC, EQ-5D, ROM and patient satisfaction. Wilcoxon and Fisher exact test were applied where alternatively appropriate. The confidence level for rejecting the null hypothesis was set at 95% (p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 288 cases were analysed. A standard parapatellar antero-medial approach was used for most procedures, while an anterolateral approach combined with tibial tuberosity osteotomy was performed in 18.1% of cases. Overall twelve orthopaedic surgeons performed the 288 surgeries, four surgeons performed the majority of cases (71.9%). All TKAs were implanted using cemented fixation, with a tourniquet applied prior to cement application. Throughout the study period, computer navigation was employed for all unconstrained and semi-constrained TKAs, whereas constrained implants were operated without computer navigation using conventional instrumentation. The postoperative protocol included standardized inpatient and outpatient physiotherapy regimens over a three-month period, which were identical for both groups. Patient and surgery related characteristics are outlined in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003ePropensity matching led to perfectly balanced baseline characteristics for both cohorts. Interestingly, this also resulted in equal WOMAC at baseline in the ptOA and pOA group (50.99 vs 51.1; p\u0026thinsp;=\u0026thinsp;0.97). Patients were 61 years old on average, and 52% were female. The vast majority of patients received unconstrained implants, while semi-constrained and constrained implants were more commonly used in the ptOA cohort.\u003c/p\u003e\n\u003cp\u003eDifferences in primary and secondary outcome parameters are outlined in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e and Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. The ptOA cohort showed significantly lower FJS-12 scores (i.e. higher joint awareness) at 1-year follow-up when compared to the pOA group (56.4 vs 71.3; p\u0026thinsp;=\u0026thinsp;0.016) despite the smaller number of completed FJS-12 questionnaires. Note that the cross-sectional mean values at baseline and 1-year post-op do not match with the improvement as a difference, as improvement was calculated for each patient with linked data and then presented as means of improvement. No significant difference in postoperative WOMAC or EQ-5D was detected between the groups. The postoperative improvement of all PROMs was not significantly different between the ptOA and pOA cohort. Overall patient satisfaction at 1-year follow-up was lower in the ptOA group. Here, 72.4% of patients were \u0026ldquo;satisfied\u0026rdquo; with the result, while this applied to 89.6% of patients in the pOA cohort (p\u0026thinsp;=\u0026thinsp;0.001). Knee flexion was significantly lower in the ptOA group, both pre- and postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Subgroup analyses for different types of implant constraint or various fracture types were not possible due to insufficient number of patients for small subgroups.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePatient characteristics\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eptOA cohort\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003epOA cohort\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e216\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eFemale (N; %)\u003c/p\u003e\n \u003cp\u003eMale (N;%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e38 (52.8%)\u003c/p\u003e\n \u003cp\u003e34 (47.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e113 (52.3%)\u003c/p\u003e\n \u003cp\u003e103 (47.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean Age (years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e61.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.82\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean BMI (kg/m\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.83\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eType of implant\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eUnconstrained *\u003c/p\u003e\n \u003cp\u003eSemi-constrained **\u003c/p\u003e\n \u003cp\u003eConstrained ***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60 (83.3%)\u003c/p\u003e\n \u003cp\u003e5 (6.9%)\u003c/p\u003e\n \u003cp\u003e7 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e202 (93.5%)\u003c/p\u003e\n \u003cp\u003e3 (1.4%)\u003c/p\u003e\n \u003cp\u003e11 (5.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eFracture pattern\u003c/strong\u003e (N; %)\u003c/p\u003e\n \u003cp\u003eProximal tibia fractures\u003c/p\u003e\n \u003cp\u003eUnicondylar lateral\u003c/p\u003e\n \u003cp\u003eUnicondylar medial\u003c/p\u003e\n \u003cp\u003eBicondylar\u003c/p\u003e\n \u003cp\u003eNot specified / unknown\u003c/p\u003e\n \u003cp\u003eDistal femur fractures\u003c/p\u003e\n \u003cp\u003eUnicondylar\u003c/p\u003e\n \u003cp\u003eBicondylar\u003c/p\u003e\n \u003cp\u003eNot specified / unknown\u003c/p\u003e\n \u003cp\u003eProximal tibia and distal femur\u003c/p\u003e\n \u003cp\u003eUnknown fracture type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e54 (75%)\u003c/p\u003e\n \u003cp\u003e20 (37%)\u003c/p\u003e\n \u003cp\u003e6 (11.1%)\u003c/p\u003e\n \u003cp\u003e22 (40.7%)\u003c/p\u003e\n \u003cp\u003e6 (11.1%)\u003c/p\u003e\n \u003cp\u003e13 (18.1%)\u003c/p\u003e\n \u003cp\u003e5 (38.5%)\u003c/p\u003e\n \u003cp\u003e5 (38.5%)\u003c/p\u003e\n \u003cp\u003e3 (23.1%)\u003c/p\u003e\n \u003cp\u003e3 (4.2%)\u003c/p\u003e\n \u003cp\u003e2 (2.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNA\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eTibial tubercle osteotomy\u003c/strong\u003e (N;%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22 (30.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30 (13.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eConcomitant interventions\u003c/strong\u003e (N; %)\u003c/p\u003e\n \u003cp\u003eHardware removal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31 (43.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNA\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e*DePuy LCS complete (2006\u0026ndash;2015) and DePuy Attune (2015\u0026ndash;2023)\u003c/p\u003e\n\u003cp\u003e**DePuy LCS Revision (2006\u0026ndash;2015) and DePuy Attune Revision (2015\u0026ndash;2023)\u003c/p\u003e\n\u003cp\u003e*** Smith\u0026amp; Nephew RT solution \u0026amp; modular (2006\u0026ndash;2023)\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;\u003ctable id=\"Tab2\" border=\"1\" class=\"fr-table-selection-hover\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eResults of primary and secondary outcome parameters\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" style=\"width: 49.1228%;\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 25.614%;\"\u003e\n \u003cp\u003eptOA cohort (N\u0026thinsp;=\u0026thinsp;72)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003epOA cohort\u003c/p\u003e\n \u003cp\u003e(N\u0026thinsp;=\u0026thinsp;216)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 49.1228%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFJS-12\u003c/strong\u003e (mean \u003cstrong\u003e\u0026plusmn;\u003c/strong\u003eSD, range)\u003c/p\u003e\n \u003cp\u003e- Pre-operative\u003c/p\u003e\n \u003cp\u003e- 1-year follow-up\u003c/p\u003e\n \u003cp\u003e- Improvement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 25.614%;\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e16.62 (18.85)\u003c/p\u003e\n \u003cp\u003e56.41 (37.93)\u003c/p\u003e\n \u003cp\u003e46.67 (33.42)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e12.78 (12.39)\u003c/p\u003e\n \u003cp\u003e71.28 (34.71)\u003c/p\u003e\n \u003cp\u003e60.34 (32.68)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.02\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 49.1228%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWOMAC\u003c/strong\u003e (mean \u003cstrong\u003e\u0026plusmn;\u003c/strong\u003eSD, range)\u003c/p\u003e\n \u003cp\u003e- Pre-operative\u003c/p\u003e\n \u003cp\u003e- 1-year follow-up\u003c/p\u003e\n \u003cp\u003e- Improvement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 25.614%;\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e50.99 (18.86)\u003c/p\u003e\n \u003cp\u003e19.95 (20.71)\u003c/p\u003e\n \u003cp\u003e29.61 (20.26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e51.10 (19.13)\u003c/p\u003e\n \u003cp\u003e15.61 (17.12)\u003c/p\u003e\n \u003cp\u003e34.56 (20.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003cp\u003e0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 49.1228%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEQ-5D\u003c/strong\u003e (mean \u003cstrong\u003e\u0026plusmn;\u003c/strong\u003eSD, range)\u003c/p\u003e\n \u003cp\u003e- Pre-operative\u003c/p\u003e\n \u003cp\u003e- 1-year follow-up\u003c/p\u003e\n \u003cp\u003e- Improvement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 25.614%;\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e0.50 (0.30)\u003c/p\u003e\n \u003cp\u003e0.75 (0.26)\u003c/p\u003e\n \u003cp\u003e0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e0.47 (0.31)\u003c/p\u003e\n \u003cp\u003e0.80 (0.26)\u003c/p\u003e\n \u003cp\u003e0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e0.52\u003c/p\u003e\n \u003cp\u003e0.14\u003c/p\u003e\n \u003cp\u003e0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 49.1228%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePatient satisfaction \u0026ldquo;satisfied\u0026rdquo;\u003c/strong\u003e (%)\u003c/p\u003e\n \u003cp\u003e- 1-year follow-up\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 25.614%;\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e72.4%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e89.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;\u0026thinsp;0.01\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 49.1228%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eROM (flexion (\u003c/strong\u003edegree); mean \u0026plusmn;SD, range\u003cstrong\u003e)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e- Pre-operative\u003c/p\u003e\n \u003cp\u003e- 1-year follow-up\u003c/p\u003e\n \u003cp\u003e- Improvement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 25.614%;\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e104.8 (23.1)\u003c/p\u003e\n \u003cp\u003e105.6 (19.4)\u003c/p\u003e\n \u003cp\u003e0.5 (18.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e115.9 (17.4)\u003c/p\u003e\n \u003cp\u003e116.6 (12.6)\u003c/p\u003e\n \u003cp\u003e-0.3 (17.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;\u0026thinsp;0.01\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;\u0026thinsp;0.01\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e0.78\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study found no significant differences in traditional PROMs with limited responsiveness (EQ-5D and WOMAC) between patients undergoing TKA for ptOA versus pOA. However, the FJS-12 revealed significantly worse outcomes in the ptOA group, indicating higher joint awareness after a previous fracture. The 14.9-point difference exceeds the minimal clinically important difference (MCID) reported in the literature ([\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] suggesting clinical relevance. Additionally, ptOA patients showed reduced knee flexion (pre- and post-op) and lower satisfaction rates at 1-year follow-up.\u003c/p\u003e \u003cp\u003ePrevious studies have reported mixed findings regarding PROMs in ptOA. Lizauer, Lunebourg and L\u0026uuml;tzner found no differences in KSS or WOMAC scores at 1- to 5-year follow-ups. Similarly, Khoshbin reported comparable KOOS, LEAS (Lower Extremity Activity Score), and SF-12 scores at 2 years post-TKA. However, these instruments, particularly WOMAC and KSS, are known to have limited responsiveness and pronounced ceiling effects, which may obscure outcome differences [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Thompson noted that the FJS-12 had a wider score distribution and greater sensitivity to group differences than WOMAC or KOOS, a finding supported by several other studies [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. These characteristics likely explain why our study, using FJS-12, identified outcome disparities missed by prior research using older tools.\u003c/p\u003e \u003cp\u003eOur satisfaction rates further support these findings: 89.6% in the pOA group versus 72.4% in the ptOA group. These align with existing literature, where satisfaction following TKA generally ranges from 85% to 90% [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Scott et al. also reported lower satisfaction in ptOA (78%) compared to pOA (86%), though their results did not reach statistical significance. The reduced satisfaction observed in our ptOA cohort may be attributed to impaired knee flexion \u0026ndash; at baseline and at 1-year follow-up and greater joint awareness, both indicative of poorer physical outcomes. Lunebourg et al. and L\u0026uuml;tzner et al. similarly reported reduced ROM in ptOA patients.\u003c/p\u003e \u003cp\u003eIt is also possible that an expectation\u0026ndash;outcome mismatch contributed to lower satisfaction in the ptOA group, as shown to impact patient-reported satisfaction in arthroplasty [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. While we were unable to measure patient expectations directly, this remains a potential explanatory factor warranting further research.\u003c/p\u003e \u003cp\u003eThis study has several limitations. First, its retrospective design and the relatively small number of patients with posttraumatic osteoarthritis (ptOA) may limit generalizability. We did not have complete longitudinal PROM data as reported in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. This predominantly affects FJS-12 data, as implementation of pre-op FJS-12 data collection in our institutional TKA register started in 2009 whereas post-op FJS-12 data collection only started in 2016 \u0026ndash; in all TKA patients \u0026ndash; primary and posttraumatic. However, data collection was conducted prospectively, and thorough review of medical records and radiographs ensured data accuracy, thereby reducing the potential for bias commonly associated with retrospective analyses.\u003c/p\u003e \u003cp\u003eTo improve comparability between groups, propensity score matching (1:3 ratio) was used to create homogeneous cohorts. This resulted in well-balanced groups with matched age, sex, and BMI, as well as perfectly comparable baseline WOMAC scores. Well validated PROMs, including the FJS-12, were employed. Notably, this is the first study to use the FJS-12 in this context, and it actually proved sensitive in distinguishing outcomes between the ptOA and primary OA (pOA) groups from the patient\u0026rsquo;s perspective.\u003c/p\u003e \u003cp\u003eAnother limitation is the absence of data on complications and revision procedures, which are well known to occur more frequently in ptOA from literature \u0026ndash; but these aspects of outcome were not the focus of this study.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003ePatients undergoing TKA for posttraumatic OA report the same outcomes as matched patients undergoing TKA for primary OA when assessed using traditional PROM tools. However, joint awareness, knee flexion and patient satisfaction are all significantly lower at 1-year in patients with posttraumatic OA, which is of relevance when counselling patients with ptOA preoperatively in order to optimize expectation management.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cem\u003eClinical trial number\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEthical Approval\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis study has been registered and approved by the ethics committee of Eastern Switzerland (EKOS; Project-ID: EKOS 2023-00813) in accordance with the Declaration of Helsinki.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConsent to participate\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAll patients provided informed consent to take part in the study.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConsent for publication\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAvailability of data and materials\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analysed during the current study are not publicly available as access to the relevant institutional database is restricted to the public, but data are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCompeting interests\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eGiesinger K is a copyright holder of the FJS-12. All other authors declare that they have no competing interests.\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eNo direct or indirect support for this project was received.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAuthors’ Contributions\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eSW and KG conceived the study. SW, AL, DFH and KG drafted the manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSW, KG and VZ were involved in analysis and interpretation of data.\u003c/p\u003e\n\u003cp\u003eSW, KG, VZ and AL provided the figures and tables. All authors edited, read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBrittain R et al. NJR statistical analysis, support and associated services National Joint Registry | 19th Annual Report. [Online]. Available: www.njrcentre.org.uk.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCharette RS, Sloan M, DeAngelis RD, Lee GC. Higher Rate of Early Revision Following Primary Total Knee Arthroplasty in Patients Under Age 55: A Cautionary Tale, Journal of Arthroplasty, vol. 34, no. 12, pp. 2918\u0026ndash;2924, Dec. 2019, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2019.06.060\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2019.06.060\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMatziolis G, Windisch C. Die posttraumatische Arthrose - eine Herausforderung? Z Orthop Unfall. 2014;152(5):510\u0026ndash;5. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1055/s-0034-1383092\u003c/span\u003e\u003cspan address=\"10.1055/s-0034-1383092\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaleh H, Yu S, Vigdorchik J, Schwarzkopf R. Total knee arthroplasty for treatment of post-traumatic arthritis: Systematic review. World J Orthop. Sep. 2016;7(9):584\u0026ndash;91. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.5312/wjo.v7.i9.584\u003c/span\u003e\u003cspan address=\"10.5312/wjo.v7.i9.584\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLunebourg A, Parratte S, Gay A, Ollivier M, Garcia-Parra K, Argenson JN. Lower function, quality of life, and survival rate after total knee arthroplasty for posttraumatic arthritis than for primary arthritis, Acta Orthop., vol. 86, no. 2, pp. 189\u0026ndash;194, Apr. 2015, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3109/17453674.2014.979723\u003c/span\u003e\u003cspan address=\"10.3109/17453674.2014.979723\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eL\u0026uuml;tzner C, Postler A, Beyer F, Lange T, Riedel R, L\u0026uuml;tzner J. Total knee arthroplasty in post-traumatic osteoarthritis is more challenging, but results in similar patient satisfaction \u0026ndash; An analysis of 1646 cases, Knee, vol. 39, pp. 116\u0026ndash;123, Dec. 2022, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.knee.2021.12.005\u003c/span\u003e\u003cspan address=\"10.1016/j.knee.2021.12.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHoudek MT, Watts CD, Shannon SF, Wagner ER, Sems SA, Sierra RJ. Posttraumatic Total Knee Arthroplasty Continues to Have Worse Outcome Than Total Knee Arthroplasty for Osteoarthritis. J Arthroplasty. Jan. 2016;31(1):118\u0026ndash;23. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2015.07.022\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2015.07.022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWeiss NG, Parvizi J, Trousdale RT, Bryce RD, Lewallen DG. Total Knee Arthroplasty in Patients with a Prior Fracture of the Tibial Plateau, 2003.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDexel J, Beyer F, L\u0026uuml;tzner C, Kleber C, L\u0026uuml;tzner J. TKA for posttraumatic osteoarthritis is more complex and needs more surgical resources. Orthopedics. May 2016;39(3):S36\u0026ndash;40. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3928/01477447-20160509-11\u003c/span\u003e\u003cspan address=\"10.3928/01477447-20160509-11\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBehrend H, Giesinger K, Giesinger JM, Kuster MS. The \u0026lsquo;Forgotten Joint\u0026rsquo; as the Ultimate Goal in Joint Arthroplasty. Validation of a New Patient-Reported Outcome Measure. J Arthroplasty. 2012;27(3). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2011.06.035\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2011.06.035\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee QJ, Chang WYE, Wong YC. Forgotten Joint Score for early outcome assessment after total knee arthroplasty: Is it really useful? Knee Surg Relat Res. Dec. 2020;32(1). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s43019-020-00049-0\u003c/span\u003e\u003cspan address=\"10.1186/s43019-020-00049-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrazier JE, Harper R, Munro J, Walters SJ. and M. L. Snaith1, Generic and condition-specific outcome measures for people with osteoarthritis of the knee, 1999.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKreibich DN et al. What Is the Best Way of Assessing Outcome After Total Knee Replacement? Lippincott-Raven Publishers, 1996. [Online]. Available: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://journals.lww.com/clinorthop\u003c/span\u003e\u003cspan address=\"http://journals.lww.com/clinorthop\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLizaur-Utrilla A, Collados-Maestre I, Miralles-Mu\u0026ntilde;oz FA, Lopez-Prats FA. Total Knee Arthroplasty for Osteoarthritis Secondary to Fracture of the Tibial Plateau. A Prospective Matched Cohort Study, Journal of Arthroplasty, vol. 30, no. 8, pp. 1328\u0026ndash;1332, Aug. 2015, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2015.02.032\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2015.02.032\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eScott CEH, Davidson E, Macdonald DJ, White TO, Keating JF. Total knee arthroplasty following tibial plateau fracture A MATCHED COHORT STUDY, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1302/0301-620X.97B4\u003c/span\u003e\u003cspan address=\"10.1302/0301-620X.97B4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGiesinger K, Hamilton DF, Jost B, Holzner B, Giesinger JM. Comparative responsiveness of outcome measures for total knee arthroplasty, Osteoarthritis Cartilage, vol. 22, no. 2, pp. 184\u0026ndash;189, Feb. 2014, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.joca.2013.11.001\u003c/span\u003e\u003cspan address=\"10.1016/j.joca.2013.11.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuhns BD, Harris WT, Domb BG. Low Ceiling Effects of the Forgotten Joint Score Compared With Legacy Measures After Joint-Preserving Procedures: A Systematic Review, Arthroscopy: The Journal of Arthroscopic \u0026amp; Related Surgery, vol. 39, no. 9, pp. 2086\u0026ndash;2095, Sep. 2023, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arthro.2023.01.107\u003c/span\u003e\u003cspan address=\"10.1016/j.arthro.2023.01.107\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLadurner A, Giesinger K, Zdravkovic V, Behrend H. The Forgotten Joint Score-12 as a valuable patient-reported outcome measure for patients after first-time patellar dislocation, Knee, vol. 27, no. 2, pp. 406\u0026ndash;413, Mar. 2020, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.knee.2019.12.004\u003c/span\u003e\u003cspan address=\"10.1016/j.knee.2019.12.004\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAngst F, Andr\u0026acute; A, Aeschlimann A, Stucki G. Smallest Detectable and Minimal Clinically Important Differences of Rehabilitation Intervention With Their Implications for Required Sample Sizes Using WOMAC and SF-36 Quality of Life Measurement Instruments in Patients With Osteoarthritis of the Lower Extremities, 2001.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW. Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee., J. Rheumatol., vol. 15, no. 12, pp. 1833\u0026ndash;40, Dec. 1988.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEckhard L, et al. The ceiling effects of patient reported outcome measures for total knee arthroplasty. Orthop Traumatology: Surg Res. May 2021;107(3). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.otsr.2020.102758\u003c/span\u003e\u003cspan address=\"10.1016/j.otsr.2020.102758\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSansone V, et al. Translation, cross-cultural adaptation, and validation of the Italian language Forgotten Joint Score-12 (FJS-12) as an outcome measure for total knee arthroplasty in an Italian population. BMC Musculoskelet Disord. Jan. 2020;21(1). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12891-019-2985-2\u003c/span\u003e\u003cspan address=\"10.1186/s12891-019-2985-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEuroQol Group. EuroQol\u0026ndash;a new facility for the measurement of health-related quality of life. Health Policy. Dec. 1990;16(3):199\u0026ndash;208. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/0168-8510(90)90421-9\u003c/span\u003e\u003cspan address=\"10.1016/0168-8510(90)90421-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClement ND, Scott CEH, Hamilton DF, MacDonald D, Howie CR. Meaningful values in the Forgotten Joint Score after total knee arthroplasty. Bone Joint J. May 2021;103\u0026ndash;B:846\u0026ndash;54. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1302/0301-620X.103B5.BJJ-2020-0396.R1\u003c/span\u003e\u003cspan address=\"10.1302/0301-620X.103B5.BJJ-2020-0396.R1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHoltz N, Hamilton DF, Giesinger JM, Jost B, Giesinger K. Minimal important differences for the WOMAC osteoarthritis index and the Forgotten Joint Score-12 in total knee arthroplasty patients. BMC Musculoskelet Disord. Jun. 2020;21(1). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12891-020-03415-x\u003c/span\u003e\u003cspan address=\"10.1186/s12891-020-03415-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIngelsrud LH, Roos EM, Terluin B, Gromov K, Husted H, Troelsen A. Minimal important change values for the Oxford Knee Score and the Forgotten Joint Score at 1 year after total knee replacement, Acta Orthop., vol. 89, no. 5, pp. 541\u0026ndash;547, Sep. 2018, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1080/17453674.2018.1480739\u003c/span\u003e\u003cspan address=\"10.1080/17453674.2018.1480739\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhoshbin A, et al. Patient-Reported Outcome Measures of Total Knee Arthroplasties for Post-Traumatic Arthritis versus Osteoarthritis: A Short-Term (5- to 10-year) Retrospective Matched Cohort Study. J Arthroplasty. May 2019;34(5):872\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2019.01.022\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2019.01.022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThompson SM, Salmon LJ, Webb JM, Pinczewski LA, Roe JP. Construct Validity and Test Re-Test Reliability of the Forgotten Joint Score, Journal of Arthroplasty, vol. 30, no. 11, pp. 1902\u0026ndash;1905, Nov. 2015, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.arth.2015.05.001\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2015.05.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKo Y et al. Nov., Comparison of the responsiveness of the SF-36, the Oxford Knee Score, and the Knee Society Clinical Rating System in patients undergoing total knee replacement, Quality of Life Research, vol. 22, no. 9, pp. 2455\u0026ndash;2459, 2013, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s11136-013-0376-y\u003c/span\u003e\u003cspan address=\"10.1007/s11136-013-0376-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KDJ. Patient satisfaction after total knee arthroplasty: Who is satisfied and who is not? in Clinical Orthopaedics and Related Research, Springer New York, 2010, pp. 57\u0026ndash;63. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s11999-009-1119-9\u003c/span\u003e\u003cspan address=\"10.1007/s11999-009-1119-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNeuprez A, et al. Patients\u0026rsquo; Expectations Impact Their Satisfaction following Total Hip or Knee Arthroplasty. PLoS ONE. Dec. 2016;11(12):e0167911. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1371/journal.pone.0167911\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0167911\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\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":"posttraumatic knee osteoarthritis, TKA, patient-reported outcome, Forgotten Joint Score-12, PROM","lastPublishedDoi":"10.21203/rs.3.rs-8668688/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8668688/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePosttraumatic osteoarthritis (ptOA) of the knee accounts for 12.5% of all total knee arthroplasties (TKA) and is associated with significantly higher complication and revision rates than in TKA for primary osteoarthritis (pOA). However, the impact of ptOA on patient-reported outcomes is less clear. The purpose of this study is to analyse longitudinal clinical and patient-reported outcomes in these patient groups.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA retrospective analysis of prospectively collected data from an institutional database was performed (time frame 2006\u0026ndash;2023). Patients with a history of intraarticular femoral or tibial fractures (ptOA) were identified, and propensity score matched (1:3 ratio) for age, sex and body mass index (BMI) to a comparable cohort receiving TKA for pOA. Outcomes at one year were assessed using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Forgotten Joint Score-12 (FJS-12), EuroQo-5D (EQ-5D), range of motion (ROM) and overall patient satisfaction.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003e72 patients with ptOA were compared to 216 matched pOA patients. There were no statistically significant differences in WOMAC (19.95 vs 15.61; p\u0026thinsp;=\u0026thinsp;0.15) or EQ-5D (0.75 vs 0.80; p\u0026thinsp;=\u0026thinsp;0.14) between the two groups at 1-year follow-up. FJS-12 showed significantly inferior result 1-year postoperatively in the ptOA group (56.4 vs 71.3; p\u0026thinsp;=\u0026thinsp;0.02). Overall patient satisfaction (72.4 vs 89.6%; p\u0026thinsp;=\u0026thinsp;0.001) and pre- and post-operative ROM (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) were also significantly worse in the ptOA group.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThere was no difference in traditional joint-specific or general heatlh scores (WOMAC or EQ5D scores) between patients with primary or posttraumatic OA. However, patients undergoing TKA for ptOA reported poorer higher-level outcomes (FJS-12 scores), poorer satisfaction rates and poorer knee flexion at 1-year.\u003c/p\u003e\u003ch2\u003eTrial Registration:\u003c/h2\u003e \u003cp\u003e Ethics committee of Eastern Switzerland EKOS; Project-ID 2023\u0026thinsp;\u0026minus;\u0026thinsp;00813, Registration date 03.05.2023\u003c/p\u003e","manuscriptTitle":"Comparative outcomes of total knee arthroplasty in patients with posttraumatic versus primary knee osteoarthritis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-23 09:37:13","doi":"10.21203/rs.3.rs-8668688/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":"a6b04515-9515-4e2f-9ca6-3e1143771673","owner":[],"postedDate":"February 23rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-06T17:54:23+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-23 09:37:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8668688","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8668688","identity":"rs-8668688","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}