Demographics and Outcomes of Unicondylar Knee Arthroplasty in Türkiye: A Nationwide Retrospective Database Study of 8590 Cases

Demographics and Outcomes of Unicondylar Knee Arthroplasty in Türkiye: A Nationwide Retrospective Database Study of 8590 Cases | 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 Demographics and Outcomes of Unicondylar Knee Arthroplasty in Türkiye: A Nationwide Retrospective Database Study of 8590 Cases Anıl Pulatkan, Fatih Yıldız, Ömer Serdar Hakyemez, Murat Birinci, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8640066/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Background Favorable long-term clinical and radiological outcomes with low revision and reoperation rates have been reported for unicondylar knee arthroplasty (UKA) in the treatment of end-stage unicompartmental knee osteoarthritis. However, no information on these data is available for the Turkish population. Our aim was to analyze the demographics, indications, outcomes, and revision rates of UKA in Türkiye using a nationwide database. Methods The electronic medical records of 8,590 patients undergoing UKA for unicompartmental osteoarthritis between 2016 and 2022 were retrospectively analyzed. Demographic data of the study population including sex, age, body mass index (BMI), and institution were assessed. The primary outcome measures were complication and revision rates. Results Of the 8,590 analyzed patients, 85.2% were women with an average age of 59 ± 8 years. The primary indication was osteoarthritis in 7,205 (94.1%) cases. Most patients received cemented implants (78% vs. 22%) and the use of fixed insert designs increased from 18% to 74% between 2018 and 2022. The overall complication rate for the study population was 5.5% (475/8,590). The rate of complications did not differ according to fixation type. However, it was statistically significantly higher in patients who received mobile UKA than the fixed design (3.8% vs. 1.8% for mechanical complications and 1.7% vs. 0.6% for other complications, respectively; P < 0.001). The overall revision rate was 4.4% (234/5,377), with rates being similar for cemented and cementless designs ( P = 0.832). However, the revision rate of mobile UKA was significantly higher than that of fixed designs ( P < 0.001). Conclusion The majority of UKAs in Türkiye were cemented implants with an increased usage of fixed bearings over time. Mobile-bearing designs had significantly greater complication and revision rates compared to fixed-bearing implants. Unicondylar knee arthroplasty fixation complication type of insert survivorship Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Total knee arthroplasty (TKA) has long been considered the gold-standard surgical intervention for the treatment of advanced knee osteoarthritis [ 1 ]. Unicondylar knee arthroplasty (UKA) is an alternative option for patients who have isolated unicompartmental or bicompartmental involvement. Selective resurfacing of the diseased compartment in UKA offers potential advantages such as reduced surgical invasiveness, preservation of intact cartilage and the ligaments of the knee, reduced blood loss, shorter hospital stay, faster recovery, and a greater “feel” of a normal knee [ 2 – 4 ]. Documentation is crucial in assessing UKA’s efficacy, outcomes, and complications and thereby optimizing patient selection and providing evidence-based recommendations for clinical practice. Registries play an important role in collecting and analyzing big data. Various arthroplasty registries have been established worldwide, the Swedish Knee Arthroplasty Register in 1976 being the first one [ 5 ]. National joint registries and electronic medical records provide generalizable and standardized data from numerous healthcare institutions on joint arthroplasty procedures [ 6 ]. These data offer a comprehensive overview of surgical procedures, implant usage, and postoperative complications on a national scale, enabling the identification of trends, variations in outcomes, and the identification of potential risk factors. Furthermore, these data provide a platform for long-term surveillance, facilitating the assessment of implant survival rates and detection of early signs of failure [ 5 , 6 ]. Such information is crucial in guiding clinical decision-making and identifying areas for quality improvement in UKA procedures. The primary aim of the current study was to identify the current trends and outcomes of UKA surgeries in the Republic of Türkiye by analyzing data from electronic medical records obtained from the Ministry of Health and national joint registries. The secondary aims were analyses of the complication and revision rates of different implant and fixation types in a large population. Material and Methods Study Settings A retrospective study was conducted using the e-Nabız database to analyze patients who underwent UKA between 2016 and 2022. The e-Nabız system is a mandatory national database system that encompasses all hospitals in Türkiye [ 7 ]. Demographic information about the patients such as sex, age, weight, height, body mass index (BMI), surgical institution, and geographical region are recorded in this database together with complication and revision rates. The study was conducted according to the Declaration of Helsinki and received approval from the Turkish Ministry of Health with a waiver of informed consent for retrospective data analysis and the health information privacy law (ID: 95741342-020/27112019) Data Collection and Study Population In addition to demographic data, this study also investigated etiology, surgical side, bilaterality, year of surgery, implant type, postoperative prosthetic complications encountered, and mortality. The comprehensive nature of the e-Nabız database allowed for a thorough analysis of these factors related to the patients’ knee arthroplasty procedures. The study population was established to include patients who underwent UKA between the years 2016 and 2022 with operation-specific procedure codes (via https://skrs.saglik.gov.tr/ ). Outcome Measures Descriptive Variables The etiology of arthritis was defined using codes from the 10th revision of the International Classification of Diseases (ICD-10). The conditions were then categorized into specific groups including gonarthrosis (knee osteoarthritis) (M17.0-9), other joint disorders (M25, M25.5, M25.8, M25.9), osteonecrosis (M87.0-9), and fractures (S72, S72.3, S72.8, S72.9, S82, S82.1). This categorization approach utilizing ICD-10 codes enabled a comprehensive understanding of the underlying causes and facilitated insights into the distribution and prevalence of different etiological factors among patients who underwent UKA. The institutions where the surgeries took place were classified into different categories including state hospitals, private hospitals, and state and private university hospitals. Additionally, the surgical regions were categorized based on Türkiye’s seven geographical regions, namely the Eastern Anatolia Region, Central Anatolia Region, Black Sea Region, Mediterranean Region, Aegean Region, Marmara Region, and Southeastern Anatolia Region. The study identified whether the femoral and tibial implants used in the surgeries were cemented or uncemented based on the Surgical and Interventional Procedure codes (SUT codes). Additionally, the study determined whether the used inserts were mobile or fixed (cemented femoral component: AP2810, AP2820; cemented tibial component: AP2900, AP2910; uncemented femoral component: AP2830, AP2840, AP2850; uncemented tibial component: AP2920, AP2930, AP2940; mobile insert: AP2860, AP2870; fixed insert: AP2880, AP2890). Analysis of postoperative complications was conducted using the relevant ICD-10 codes, which encompassed a range of conditions. These included pneumonia (J12-18), deep venous thromboembolism (DVT; I82), pulmonary embolism (I26), acute/chronic renal failure (N17), urinary tract infection (UTI; N39.0), electrolyte and acid-base imbalances (E87), sciatic (G57.0) or femoral nerve injury (G57.2), and gastrointestinal bleeding (hematemesis, melena, etc.; K92), as well as prosthetic revision surgeries via operation codes. Implant-related complications were identified utilizing the SUT and ICD codes entered into the system. Mortality-related Variables Postoperative mortality rates following primary surgery were assessed for the entire study population from the day of the index operation to the day of death. Data Analyses Data analysis was conducted using IBM SPSS Statistics 25.0 (IBM Corp., Armonk, NY, USA). To assess the normality of the data distribution, we employed skewness and kurtosis values. Skewness provided insights into the degree of asymmetry of the distribution, while kurtosis indicated the extent of the data’s peakedness. Both measures were instrumental in determining whether our dataset conformed to a Gaussian distribution. For categorical variables, comparisons were made using the Pearson chi -square test to understand the relationships and associations between categories. For parametric variables, we utilized an independent sample t -test to compare means and discern significant differences. Quantitative variables were presented as mean values accompanied by standard deviations (mean ± SD). On the other hand, qualitative variables were given as counts (n), frequencies, or in ratio form. Throughout our analysis, a threshold of P < 0.05 was adopted to denote statistical significance, ensuring that our findings were robust and not merely the result of random chance. Results Descriptive Variables A total of 8,590 patients (85.2% women) who underwent UKA from January 2016 through December 2022 were included in this study. The mean age of the patients was 59 ± 8 years (range, 18–90), mean BMI was 32 ± 5 (range, 18–53), and mean length of stay was 4 ± 2 days (range, 0–8). Indications for UKA were primary osteoarthritis in 7,205 (94.1%) cases, undefined knee joint pain in 431 (5.6%), and osteonecrosis in 18 (0.2%). Single-stage bilateral surgery was reported for only 21 (0.2%) patients. The numbers of patients undergoing UKA over the study period are shown in Fig. 1 . Figure 2 outlines the distribution of the overall study population according to the geographic regions of Türkiye. We found that more than half of the patients were operated on in the Marmara and Aegean regions. Figure 3 demonstrates the distribution of the patients according to hospital type; more than half of the patients underwent their surgeries in state hospitals. Implant Selection The type of implant was recorded for 5,377 knees. Within this population, mobile-bearing (MB) designs were slightly more frequent than fixed-bearing (FB) designs (52% vs. 48%). The comparison of demographic characteristics and complication rates of the groups in terms of the type of implant is summarized in Table 1 . There were significantly more women in the MB group than in the FB group ( P < 0.01) and uncemented prostheses were implanted significantly more often in this group ( P < 0.01). The distribution of implant selection in Türkiye over the years is shown in Fig. 4 . Table 1 Comparisons of the demographics and outcomes by bearing design Demographic n Patients with Mobile Bearing Patients with Fixed Bearing p value Age (Years) 5377 60 ± 8 59 ± 8 0.615 a Sex (Female/Male) 5377 2417(86%) / 381(14%) 2149(83%) / 430(17%) < 0.01 b Weight (kg) 5103 81.8 ± 13.2 82.3 ± 13.1 0.410 a BMI 5103 31.7 ± 5.3 31.7 ± 5.1 0.944 a Postoperative Mortality (n) 6 4 2 Complication (+/-) 5377 181(6%) / 2617(94%) 81(3%) / 2498(97%) < 0.001 b Mechanical (+/-) 5263 102(4%) / 2617(96%) 46(2%) / 2498(98%) < 0.001 b Infection (+/-) 5167 33(< 1%) / 2617(99%) 19(< 1%) /2498(99%) 0.094 b Other (+/-) 5177 46(2%) / 2617(98%) 16(< 1%) /2498(99%) < 0.001 b Revision (+/-) 5377 175(6%) / 2623(94%) 59(2%) /2520(98%) < 0.001 b Type of fixation (Uncemented/ Cemented/ Hybrid) 5377 1185(43%) / 1549(55%) / 64(2%) 0 / 2579(100%) / 0 < 0.001 c BMI: Body mass index, n: Number of patients a : Independent sample t test, b : Fisher exact test, c : Pearson Chi-square test Cemented fixation was used for 77% of the femoral components and 78% of the tibial baseplates, being significantly more frequent than uncemented fixation. Patients who underwent hybrid fixation were excluded from the analysis due to the small sample size. Comparisons of the demographic data and outcomes of the fixation types are summarized in Table 2 . There were significantly more men ( P < 0.01) among the patients who underwent cemented UKA, and FB implants were also more common in this group ( P < 0.01). Figure 5 outlines the distribution of the overall study population according to fixation type. Table 2 Comparison of the demographics and outcomes by fixation type Uncemented UKA (n = 1185) Cemented UKA (n = 4128) p value Age (Years) 59 ± 8 59 ± 8 0.307 a Sex (Women/Men) 1031/154 3489/639 0.037 b Weight (kg) 81 ± 12 82 ± 13 0.278 a BMI 31 ± 5 32 ± 5 0.171 a LOS (Days) 4.3 ± 1.8 4.1 ± 1.8 0.065 a Postoperative Mortality (n) 3 3 Complication (n) 65 (5%) 190 (5%) 0.217 b Mechanical (n) 41 (3%) 105 (3%) Infection (n) 13 (1%) 35 (1%) Other (n) 11 (1%) 50 (1%) Revision (n) 54 (5%) 178 (4%) 0.832 b Type of Insert (Mobil/Fixed) 1185 (100%) / 0 1549 (38%) / 2579 (62%) < 0.01 b BMI: Body mass index, LOS: Length of stay, n: Number of patients, PKA: Unicondylar knee arthroplasty a : Independent sample t test, b : Fisher exact test Complications The overall complication rate of the study population was 5.5% (475/8,590). The complications were classified as mechanical complications (n = 254; 3%), infection (n = 94; 1.1%), and others (n = 127; 1.5%). The mean time to occurrence of a postoperative complication was 678 ± 653 days (range, 4 − 2,560). UKA complication rates in Türkiye by years are shown in Fig. 6 . Complication rates by hospital types are given in Table 3 . The rate of complications was found to be statistically significantly lower in state university hospitals than private hospitals ( P < 0.01). Other comparisons were not statistically significant. The overall patient population was divided into two groups according to the occurrence of any complication (Table 4 ). There was a significant difference among the types of fixation in terms of the occurrence of complications ( P = 0.035). Subgroup analysis demonstrated a significant difference between cemented and hybrid fixation ( P = 0.029), but complication rates were similar for cemented and cementless fixation. The rate of complications was significantly greater among patients who underwent MB UKA compared to the FB group with rates of 3.8% versus 1.8% ( P < 0.001) for mechanical complications and 1.7% versus 0.6% ( P < 0.001) for any other complications, respectively. The overall revision rate for the study population was 4.4% (234/5,377). The revision rates of cemented and uncemented systems were similar ( P = 0.832). However, the revision rate of MB UKA was significantly higher than that of FB designs ( P < 0.001). Table 3 Comparison of complication rates in Türkiye according to hospital types. Hospital type Complication rates (%) p values State University Hospitals 37/1039 (3.6%) < 0.01 a Private University Hospitals 22/386 (5.7%) Private Hospitals 191/2526 (7.6%) State Hospital & Training Hospitals 225/4636 (4.9%) a: Pearson Chi-square test. In subgroup analysis, a significant difference was found between state university hospitals and private hospitals (p < 0.01). Table 4 Comparison of patients’ demographics according to occurrence of complications n Patients without Complications Patients with Complications p value Age (Years) 8590 59 ± 8 59 ± 9 0.869 a Sex (Women/Men) 8590 6907(85%) /1208(15%) 408(86%) / 67(14%) 0.690 b Weight (kg) 3378 82 ± 13 83 ± 15 0.161 a BMI 3378 32 ± 5 32 ± 5 0.605 a Insert type (Mobile/Fixed) 5377 2617(51%) / 2498(49%) 181(69%)/81(31%) < 0.001 b Type of fixation (Uncemented/ Cemented/ Hybrid) 5377 1120/3938/57 65/190/7 0.035 c BMI: Body mass index, n: Number of patients a : Independent sample t test, b : Fisher exact test, c : Pearson Chi-square test Postoperative Mortality Rates The overall mortality rate was < 0.1% (1/8,590) in the first 10 days after the primary surgery and < 0.1% (3/8,590) in the first postoperative month, and < 0.1% (6/8,590) of the patients had died at the final follow-up. The mean time from index operation to death was 37 ± 24 days (range, 3–62). Discussion The most important finding of this study was that complication rates were significantly higher among patients treated with MB implants compared to FB implants. This might be one of the reasons for the increased utilization of FB over time, from 18% at the beginning of the study period to 74% after 2018. However, we found no significant difference in complication rates between cemented and cementless UKAs. In addition, there were significantly fewer complications in state university hospitals, where UKA was performed more frequently, compared to private hospitals. This is the first nationwide study analyzing prospectively collected data of the Turkish Ministry of Health about UKA. In Türkiye, the majority of patients are reimbursed by the public insurance system and registration in the database of the Turkish Ministry of Health is mandatory. Therefore, this cohort is representative of more than 90% of the UKA surgeries performed in the country. Although there are some limitations to the types of data available, we were able to analyze revision rates and subtypes of complications as mechanical or septic. Trends in design and fixation preferences over the years were observed and geographical data could be correlated with outcomes. Similar to our results, many comparative studies in the literature have demonstrated that cementless UKA is a safe option and has comparable, if not better, interim results compared to cemented fixation [ 8 – 10 ]. Mancino et al reported that the revision rate for cemented UKA was significantly higher (10.2% at 5.7-year follow-up) than that of cementless fixation (5.8% at 4.1-year follow-up in 4,776 patients) [ 9 ]. A systematic review by Mohammad et al showed that the annual revision rate of cementless UKA was almost two-thirds that of cemented UKA [ 10 ]. Data from the New Zealand Joint Registry (NZJR) including 1,473 revisions of 16,890 registered UKAs reported that the revision rate of cementless UKA (304/6,781) was significantly lower than that of cemented implants (1,106/9,382) [ 11 ]. Similar to the NZJR, data from the British National Joint Registry (NJR) on the cumulative revision rates of 103,385 cemented and 33,508 cementless UKAs revealed that the revision rate for cementless implants was lower than that for cemented UKAs (5.4% vs. 3.7% at 5 years and 10% vs. 7.4% at 10 years) [ 12 ]. The reasons for revisions for cemented UKAs were the progression of osteoarthritis, aseptic loosening, and pain. For the uncemented group, the most common reason was instability rather than pain. The incidences of revisions for pain and aseptic loosening were lower for cementless UKAs compared to cemented fixation. A Dutch database from 2022, which included 32,276 UKAs, showed that the usage of cemented UKA decreased from 80% to less than 40% from 2012 to 2021. The cumulative revision rate of cemented UKA was found to be higher than that of cementless UKA (8% vs. 5% at 5 years and 12% vs. 8% at 10 years) [ 13 ]. The 2021 Annual Report of the Swedish Arthroplasty Register noted that before 2010 almost all UKAs were cemented but after 2013 this changed. In 2020, 58.5% of UKAs were cementless and 1.1% used hybrid fixation; this increase was due to the popularity of Oxford implants, 94% of which were uncemented [ 14 ]. In our study, 4,128 of 5,313 patients underwent cemented UKA between 2016 and 2022. Cemented fixation continues to be used more frequently since 2012. We found that the rate and type of complications were similar between cemented and cementless fixation. Interestingly, the complication rate was significantly higher in the fully cemented fixation group compared to hybrid fixation (11% vs. 5%, P < 0.01). The MB and FB UKA designs have specific advantages and shortcomings. The MB design has a large contact area and has become popular for minimizing polyethylene contact stress and wear [ 15 , 16 ]. This theoretically reduces the risk of long-term aseptic loosening, polyethylene wear, and implant revision by providing less contact stress and more compatible bearing surfaces with large contact areas. On the other hand, a lack of precise alignment and ligament balancing can cause bearings to dislodge or warp, resulting in increased wear [ 17 ]. Furthermore, MB UKA is considered to be technically demanding due to difficulties in balancing the knee [ 18 ]. In contrast, FB designs are less technically demanding and insert dislocation is not an issue. However, the flat and less conforming design may lead to earlier polyethylene wear compared to mobile designs due to decreased contact area and increased contact pressure [ 19 ]. Conflicting outcomes have been reported in the literature regarding insert type, and debate continues as to which prosthetic design has superior long-term outcomes [ 20 , 21 ]. Zhang et al published a meta-analysis of 17 studies including 2,612 knees comparing MB and FB designs and found no difference in radiological and clinical outcomes, revision rates, or survivorship [ 20 ]. In another meta-analysis, Migliorini et al collected data from 25 studies of 4,696 patients and reported no difference in functional outcomes, complications, or implant survivorship between bearing types [ 22 ]. The 2022 German Arthroplasty Registry Report compared the revision rates of 26,033 MB and 16,866 FB procedures [ 23 ]. The revision rates were found to be similar at both 5 years (7.1% vs. 7.5%) and 7 years (7.8% vs. 8.6%). However, MBs were utilized less frequently in 2022; the percentage was only 53.8% compared to 71.6% in 2014. The Australian Orthopaedic Association’s National Joint Replacement Registry reported the outcomes of 22,229 MB and 23,193 FB procedures in 2021 and MB implants from two different manufacturers in this registry had an increased risk of revision for both medial and lateral UKAs [ 24 ]. The cumulative percent revision rates of UKAs were 5.2% versus 7.6% at 5 years and 9.3% versus 13.8% at 10 years for FB and MB designs, respectively. The NJR, including data from all participating hospitals in England, Wales, Northern Ireland, the Isle of Man, and Guernsey, compared 82,117 MB and 57,767 FB designs [ 12 ]. The 5-year Kaplan-Meier estimates of the cumulative revision rates for cemented and cementless FB designs were 3.8% and 5.3%, and for MB designs they were 6.4% and 3.6%, respectively. In the current study, the rate of complications was found to be significantly higher for MB compared to FB designs as overall (6% vs. 3%), mechanical (4% vs. 2%), and other complications (2% vs. <1%) were all higher among patients who had received MB implants. The revision rate for MB implants was also significantly higher (6% vs. 2%). It is widely accepted that UKA has higher complication and revision rates compared to TKA [ 12 , 25 ]. The 2022 German Arthroplasty Registry Annual Report revealed that the revision probability of UKA was almost twice that of TKA and its cumulative revision rate at 5 years was as high as 7%. Centers performing fewer than 30 UKAs annually had a cumulative revision rate of more than twice that of centers performing more than 100 UKAs [ 23 ]. This negative correlation between surgical volume and complications and revision rates in UKA is important. Higher patient volume has been shown to reduce the risk of revision [ 26 ]. In a study using NJR data, revision rates reached acceptable levels when the surgeons performed UKAs in at least 20% of their overall knee arthroplasty caseloads [ 27 ]. That study found optimum outcomes when the surgeon’s UKA usage was between 40% and 60%; more importantly, surgeons with UKA caseloads of < 5% had the highest revision rates [ 27 ]. In another study, Murray et al showed that a minimum yearly caseload of 12 UKAs significantly decreased the revision rate [ 28 ]. Klasan et al analyzed 131,575 UKAs from the UK, Australian, and New Zealand registries and classified surgeons according to their surgical volumes. Surprisingly, more than 50% of the knee surgeons in each registry had a proportion of less than 5% UKA compared to TKA in clinical practice [ 29 ]. Although surgical volumes of the surgeons and hospitals were not analyzed in our study, the complication and revision rates of UKA were found to be significantly lower in state university hospitals in Türkiye, where UKA is applied more frequently compared to private institutions. This study had several limitations. The data were collected from a national database and potential errors in data input from hospitals on the etiology of arthritis, patient demographics, and comorbidities might have produced a bias. No data were available on the type of UKA; therefore, distinctions between medial, lateral, and bicompartmental arthroplasties could not be made. Patient-reported outcome measures were not recorded in the database. Complications were classified as “mechanical,” “infection,” and “others” and no data were available on the number of patients who had aseptic loosening, insert dislocation, periprosthetic fracture, collapse, or disease progression. Data on the implant manufacturer were available in only a limited number of cases; therefore, Kaplan-Meier survivorship analysis could not be performed for specific implants. The strength of this study is that it provided an accurate overview of the current situation in Türkiye, covering more than 90% of the procedures performed in the country due to the mandatory nature of the registry. Future work will focus on improving the database while keeping the above-mentioned shortcomings in mind. Conclusions This study has presented the registry data of the Ministry of Health of Türkiye, constituting the largest patient volume of UKA in the country. The majority of the UKAs in Türkiye were performed as cemented implants with an increased usage of fixed bearings over time. Mobile-bearing designs had significantly greater complication and revision rates compared to fixed-bearing implants. These results may help orthopaedic surgeons in decision-making processes for the treatment of knee osteoarthritis. We hope that our results will raise the awareness of health care authorities regarding the importance of implant registries and lead to improvements in data collection and analysis. Declarations Funding None Declaration of Generative AI and AI-assisted technologies in the writing process During the preparation of this work the authors used ChatGPT in order to edit the language quality and grammer of the text. Author Contribution A.P. and F.Y. wrote the manuscriptÖ.S.H. made the statistical analysisM.B. prepared the tables and figuresB.A., İ.B., İ.A., R.T., İ.T., made suggestions and corrections for the manuscriptN.A., M.M.Ü., Ş.B., M.O.A., provided and sorted the data, made the data clearer for the analysis References Carr AJ, Robertsson O, Graves S, Price AJ, Arden NK, Judge A et al (2012) Knee replacement. 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Sci Rep 10:19075. 10.1038/s41598-020-76124-z Catani F, Benedetti MG, Bianchi L, Marchionni V, Giannini S, Leardini A (2012) Muscle activity around the knee and gait performance in unicompartmental knee arthroplasty patients: a comparative study on fixed- and mobile-bearing designs. Knee Surg Sports Traumatol Arthrosc 20:1042–1048. 10.1007/s00167-011-1620-z Migliorini F, Maffulli N, Cuozzo F, Elsner K, Hildebrand F, Eschweiler J et al (2022) Mobile bearing versus fixed bearing for unicompartmental arthroplasty in monocompartmental osteoarthritis of the knee: a meta-analysis. J Clin Med 11:2837. 10.3390/jcm11102837 German Arthroplasty Registry (EPRD). EPRD Annual Report 2022. Berlin, Germany: EPRD Deutsche Endoprothesenregister gGmbH (2022) Available at https://www.eprd.de/en/about-the-eprd/news/article/eprd-annual-report-2022 Australian Orthopaedic Association National Joint Replacement Registry. Hip, Knee & Shoulder Arthroplasty 2022 ANNUAL REPORT. Adelaide, Australia: AOA (2022) Available at https://aoanjrr.sahmri.com/annual-reports-2022 Wilson HA, Middleton R, Abram SGF, Smith S, Alvand A, Jackson WF et al (2019) Patient relevant outcomes of unicompartmental versus total knee replacement: systematic review and meta-analysis. BMJ 364:l352. 10.1136/bmj.l352 Murray DW, Liddle AD, Dodd CA, Pandit H (2015) Unicompartmental knee arthroplasty: is the glass half full or half empty? Bone Joint J 97-B(10 Suppl. A):3–8. 10.1302/0301-620X.97B10.36542 Liddle AD, Pandit H, Judge A, Murray DW (2015) Optimal usage of unicompartmental knee arthroplasty: a study of 41,986 cases from the National Joint Registry for England and Wales. Bone Joint J 97:1506–1511. 10.1302/0301-620X.97B11.35551 Murray D, Parkinson R (2018) Usage of unicompartmental knee arthroplasty. Bone Joint J 100:432–435. 10.1302/0301-620X.100B4.BJJ-2017-0716.R1 Klasan A, Parker DA, Lewis PL, Young SW (2022) Low percentage of surgeons meet the minimum recommended unicompartmental knee arthroplasty usage thresholds: analysis of 3037 surgeons from three national joint registries. Knee Surg Sports Traumatol Arthrosc 30:958–964. 10.1007/s00167-021-06437-7 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 30 Jan, 2026 Reviews received at journal 30 Jan, 2026 Reviewers agreed at journal 30 Jan, 2026 Reviewers invited by journal 29 Jan, 2026 Editor assigned by journal 28 Jan, 2026 Submission checks completed at journal 28 Jan, 2026 First submitted to journal 19 Jan, 2026 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. 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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-8640066","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":583259124,"identity":"5c1888f9-a9fe-460d-b4fb-c39b48e97f2f","order_by":0,"name":"Anıl 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13:59:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8640066/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8640066/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101654217,"identity":"5b540f6e-1777-4ab5-b8a8-78d3160c2133","added_by":"auto","created_at":"2026-02-02 09:43:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":40054,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of the patients undergoing unicondylar knee arthroplasty between 2016 and 2022.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8640066/v1/ef00613ed21e6489a808ac64.png"},{"id":101654215,"identity":"520f90fe-ca27-41ec-974b-cef7f0fe04ee","added_by":"auto","created_at":"2026-02-02 09:43:13","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":56277,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of the patients undergoing unicondylar knee arthroplasty by hospital type.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8640066/v1/400d722280a9ef9d52ff4c99.png"},{"id":101654218,"identity":"e4c95177-20a6-44f1-8495-1cb98351af8a","added_by":"auto","created_at":"2026-02-02 09:43:16","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":69572,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of the patients undergoing unicondylar knee arthroplasty by geographic region.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8640066/v1/5b3c8e12d637cd0e483b8e5e.png"},{"id":101654241,"identity":"cefb90d7-eb08-4693-9667-91458e073060","added_by":"auto","created_at":"2026-02-02 09:43:19","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":70481,"visible":true,"origin":"","legend":"\u003cp\u003eImplant selection in Türkiye between 2016 and 2022.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8640066/v1/fdd2986c16b6d5ac95abe8fa.png"},{"id":101654242,"identity":"d66b9b23-52b5-4860-9eb4-aa8958c2f014","added_by":"auto","created_at":"2026-02-02 09:43:19","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":33691,"visible":true,"origin":"","legend":"\u003cp\u003eType of fixation of unicondylar knee arthroplasty in Türkiye between 2016 and 2022.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8640066/v1/cb174843f0b08aa79c19d546.png"},{"id":101654214,"identity":"c95e3553-47fd-4625-9ec6-044dd60460f2","added_by":"auto","created_at":"2026-02-02 09:43:12","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":31645,"visible":true,"origin":"","legend":"\u003cp\u003eType of complications of unicondylar knee arthroplasty by years in Türkiye.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8640066/v1/e36f65327adf9e623f5dff0c.png"},{"id":101654298,"identity":"50bf46eb-9d4e-4bc2-81a4-3743a6717a8c","added_by":"auto","created_at":"2026-02-02 09:43:28","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1407570,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8640066/v1/bbd61e3a-a001-49ff-8517-63eca1a06f98.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Demographics and Outcomes of Unicondylar Knee Arthroplasty in Türkiye: A Nationwide Retrospective Database Study of 8590 Cases","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTotal knee arthroplasty (TKA) has long been considered the gold-standard surgical intervention for the treatment of advanced knee osteoarthritis [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Unicondylar knee arthroplasty (UKA) is an alternative option for patients who have isolated unicompartmental or bicompartmental involvement. Selective resurfacing of the diseased compartment in UKA offers potential advantages such as reduced surgical invasiveness, preservation of intact cartilage and the ligaments of the knee, reduced blood loss, shorter hospital stay, faster recovery, and a greater \u0026ldquo;feel\u0026rdquo; of a normal knee [\u003cspan additionalcitationids=\"CR3\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDocumentation is crucial in assessing UKA\u0026rsquo;s efficacy, outcomes, and complications and thereby optimizing patient selection and providing evidence-based recommendations for clinical practice. Registries play an important role in collecting and analyzing big data. Various arthroplasty registries have been established worldwide, the Swedish Knee Arthroplasty Register in 1976 being the first one [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. National joint registries and electronic medical records provide generalizable and standardized data from numerous healthcare institutions on joint arthroplasty procedures [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. These data offer a comprehensive overview of surgical procedures, implant usage, and postoperative complications on a national scale, enabling the identification of trends, variations in outcomes, and the identification of potential risk factors. Furthermore, these data provide a platform for long-term surveillance, facilitating the assessment of implant survival rates and detection of early signs of failure [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Such information is crucial in guiding clinical decision-making and identifying areas for quality improvement in UKA procedures.\u003c/p\u003e \u003cp\u003eThe primary aim of the current study was to identify the current trends and outcomes of UKA surgeries in the Republic of T\u0026uuml;rkiye by analyzing data from electronic medical records obtained from the Ministry of Health and national joint registries. The secondary aims were analyses of the complication and revision rates of different implant and fixation types in a large population.\u003c/p\u003e"},{"header":"Material and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Settings\u003c/h2\u003e \u003cp\u003eA retrospective study was conducted using the e-Nabız database to analyze patients who underwent UKA between 2016 and 2022. The e-Nabız system is a mandatory national database system that encompasses all hospitals in Türkiye [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Demographic information about the patients such as sex, age, weight, height, body mass index (BMI), surgical institution, and geographical region are recorded in this database together with complication and revision rates. The study was conducted according to the Declaration of Helsinki and received approval from the Turkish Ministry of Health with a waiver of informed consent for retrospective data analysis and the health information privacy law (ID: 95741342-020/27112019)\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eData Collection and Study Population\u003c/h3\u003e\n\u003cp\u003eIn addition to demographic data, this study also investigated etiology, surgical side, bilaterality, year of surgery, implant type, postoperative prosthetic complications encountered, and mortality. The comprehensive nature of the e-Nabız database allowed for a thorough analysis of these factors related to the patients’ knee arthroplasty procedures.\u003c/p\u003e \u003cp\u003eThe study population was established to include patients who underwent UKA between the years 2016 and 2022 with operation-specific procedure codes (via \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://skrs.saglik.gov.tr/\u003c/span\u003e\u003cspan address=\"https://skrs.saglik.gov.tr/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eOutcome Measures\u003c/h3\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eDescriptive Variables\u003c/h2\u003e \u003cp\u003eThe etiology of arthritis was defined using codes from the 10th revision of the International Classification of Diseases (ICD-10). The conditions were then categorized into specific groups including gonarthrosis (knee osteoarthritis) (M17.0-9), other joint disorders (M25, M25.5, M25.8, M25.9), osteonecrosis (M87.0-9), and fractures (S72, S72.3, S72.8, S72.9, S82, S82.1). This categorization approach utilizing ICD-10 codes enabled a comprehensive understanding of the underlying causes and facilitated insights into the distribution and prevalence of different etiological factors among patients who underwent UKA.\u003c/p\u003e \u003cp\u003eThe institutions where the surgeries took place were classified into different categories including state hospitals, private hospitals, and state and private university hospitals. Additionally, the surgical regions were categorized based on Türkiye’s seven geographical regions, namely the Eastern Anatolia Region, Central Anatolia Region, Black Sea Region, Mediterranean Region, Aegean Region, Marmara Region, and Southeastern Anatolia Region.\u003c/p\u003e \u003cp\u003eThe study identified whether the femoral and tibial implants used in the surgeries were cemented or uncemented based on the Surgical and Interventional Procedure codes (SUT codes). Additionally, the study determined whether the used inserts were mobile or fixed (cemented femoral component: AP2810, AP2820; cemented tibial component: AP2900, AP2910; uncemented femoral component: AP2830, AP2840, AP2850; uncemented tibial component: AP2920, AP2930, AP2940; mobile insert: AP2860, AP2870; fixed insert: AP2880, AP2890).\u003c/p\u003e \u003cp\u003eAnalysis of postoperative complications was conducted using the relevant ICD-10 codes, which encompassed a range of conditions. These included pneumonia (J12-18), deep venous thromboembolism (DVT; I82), pulmonary embolism (I26), acute/chronic renal failure (N17), urinary tract infection (UTI; N39.0), electrolyte and acid-base imbalances (E87), sciatic (G57.0) or femoral nerve injury (G57.2), and gastrointestinal bleeding (hematemesis, melena, etc.; K92), as well as prosthetic revision surgeries via operation codes. Implant-related complications were identified utilizing the SUT and ICD codes entered into the system.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMortality-related Variables\u003c/h3\u003e\n\u003cp\u003ePostoperative mortality rates following primary surgery were assessed for the entire study population from the day of the index operation to the day of death.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eData Analyses\u003c/h2\u003e \u003cp\u003eData analysis was conducted using IBM SPSS Statistics 25.0 (IBM Corp., Armonk, NY, USA). To assess the normality of the data distribution, we employed skewness and kurtosis values. Skewness provided insights into the degree of asymmetry of the distribution, while kurtosis indicated the extent of the data’s peakedness. Both measures were instrumental in determining whether our dataset conformed to a Gaussian distribution. For categorical variables, comparisons were made using the Pearson \u003cem\u003echi\u003c/em\u003e-square test to understand the relationships and associations between categories. For parametric variables, we utilized an independent sample \u003cem\u003et\u003c/em\u003e-test to compare means and discern significant differences. Quantitative variables were presented as mean values accompanied by standard deviations (mean ± SD). On the other hand, qualitative variables were given as counts (n), frequencies, or in ratio form. Throughout our analysis, a threshold of \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.05 was adopted to denote statistical significance, ensuring that our findings were robust and not merely the result of random chance.\u003c/p\u003e \u003c/div\u003e\n\n \n\n "},{"header":"Results","content":"\u003ch3\u003eDescriptive Variables\u003c/h3\u003e\u003cp\u003eA total of 8,590 patients (85.2% women) who underwent UKA from January 2016 through December 2022 were included in this study. The mean age of the patients was 59 ± 8 years (range, 18–90), mean BMI was 32 ± 5 (range, 18–53), and mean length of stay was 4 ± 2 days (range, 0–8). Indications for UKA were primary osteoarthritis in 7,205 (94.1%) cases, undefined knee joint pain in 431 (5.6%), and osteonecrosis in 18 (0.2%). Single-stage bilateral surgery was reported for only 21 (0.2%) patients. The numbers of patients undergoing UKA over the study period are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e outlines the distribution of the overall study population according to the geographic regions of Türkiye. We found that more than half of the patients were operated on in the Marmara and Aegean regions. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e demonstrates the distribution of the patients according to hospital type; more than half of the patients underwent their surgeries in state hospitals.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003ch3\u003eImplant Selection\u003c/h3\u003e\u003cp\u003eThe type of implant was recorded for 5,377 knees. Within this population, mobile-bearing (MB) designs were slightly more frequent than fixed-bearing (FB) designs (52% vs. 48%). The comparison of demographic characteristics and complication rates of the groups in terms of the type of implant is summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There were significantly more women in the MB group than in the FB group (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.01) and uncemented prostheses were implanted significantly more often in this group (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.01). The distribution of implant selection in Türkiye over the years is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparisons of the demographics and outcomes by bearing design\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDemographic\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePatients with\u003c/p\u003e \u003cp\u003e Mobile Bearing\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePatients with \u003c/p\u003e \u003cp\u003eFixed Bearing\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep value\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (Years)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5377\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e60 ± 8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e59 ± 8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.615\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex (Female/Male)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5377\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2417(86%) / 381(14%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2149(83%) / 430(17%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt; 0.01\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWeight (kg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5103\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e81.8 ± 13.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e82.3 ± 13.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.410\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5103\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31.7 ± 5.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e31.7 ± 5.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.944\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePostoperative Mortality (n)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eComplication (+/-)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5377\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e181(6%) / 2617(94%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e81(3%) / 2498(97%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt; 0.001\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMechanical\u003c/b\u003e \u003cb\u003e(+/-)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5263\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e102(4%) / 2617(96%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e46(2%) / 2498(98%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt; 0.001\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInfection\u003c/b\u003e \u003cb\u003e(+/-)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5167\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33(\u0026lt; 1%) / 2617(99%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19(\u0026lt; 1%) /2498(99%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.094\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOther\u003c/b\u003e \u003cb\u003e(+/-)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5177\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46(2%) / 2617(98%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16(\u0026lt; 1%) /2498(99%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt; 0.001\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRevision\u003c/b\u003e \u003cb\u003e(+/-)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5377\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e175(6%) / 2623(94%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e59(2%) /2520(98%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt; 0.001\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eType of fixation \u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(Uncemented/ Cemented/ Hybrid)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5377\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1185(43%) / 1549(55%) / 64(2%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 / 2579(100%) / 0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt; 0.001\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eBMI: Body mass index, n: Number of patients\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003csup\u003ea\u003c/sup\u003e: Independent sample t test, \u003csup\u003eb\u003c/sup\u003e: Fisher exact test, \u003csup\u003ec\u003c/sup\u003e: Pearson Chi-square test\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cp\u003eCemented fixation was used for 77% of the femoral components and 78% of the tibial baseplates, being significantly more frequent than uncemented fixation. Patients who underwent hybrid fixation were excluded from the analysis due to the small sample size. Comparisons of the demographic data and outcomes of the fixation types are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. There were significantly more men (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.01) among the patients who underwent cemented UKA, and FB implants were also more common in this group (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.01). Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e outlines the distribution of the overall study population according to fixation type.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the demographics and outcomes by fixation type\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUncemented UKA\u003c/p\u003e \u003cp\u003e(n = 1185)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCemented UKA\u003c/p\u003e \u003cp\u003e(n = 4128)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep value\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (Years)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59 ± 8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59 ± 8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.307\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex (Women/Men)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1031/154\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3489/639\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e0.037\u003c/b\u003e\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWeight (kg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e81 ± 12\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e82 ± 13\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.278\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31 ± 5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32 ± 5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.171\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLOS (Days)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.3 ± 1.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.1 ± 1.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e0.065\u003c/b\u003e\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePostoperative Mortality (n)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eComplication (n)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65 (5%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e190 (5%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.217\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMechanical (n)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41 (3%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e105 (3%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInfection (n)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (1%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35 (1%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOther (n)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (1%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50 (1%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRevision (n)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e54 (5%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e178 (4%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.832\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eType of Insert (Mobil/Fixed)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1185 (100%) / 0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1549 (38%) / 2579 (62%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt; 0.01\u003c/b\u003e\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eBMI: Body mass index, LOS: Length of stay, n: Number of patients, PKA: Unicondylar knee arthroplasty\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003csup\u003ea\u003c/sup\u003e: Independent sample t test, \u003csup\u003eb\u003c/sup\u003e: Fisher exact test\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003ch2\u003eComplications\u003c/h2\u003e\u003cp\u003eThe overall complication rate of the study population was 5.5% (475/8,590). The complications were classified as mechanical complications (n = 254; 3%), infection (n = 94; 1.1%), and others (n = 127; 1.5%). The mean time to occurrence of a postoperative complication was 678 ± 653 days (range, 4 − 2,560). UKA complication rates in Türkiye by years are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. Complication rates by hospital types are given in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The rate of complications was found to be statistically significantly lower in state university hospitals than private hospitals (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.01). Other comparisons were not statistically significant. The overall patient population was divided into two groups according to the occurrence of any complication (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). There was a significant difference among the types of fixation in terms of the occurrence of complications (\u003cem\u003eP\u003c/em\u003e = 0.035). Subgroup analysis demonstrated a significant difference between cemented and hybrid fixation (\u003cem\u003eP\u003c/em\u003e = 0.029), but complication rates were similar for cemented and cementless fixation. The rate of complications was significantly greater among patients who underwent MB UKA compared to the FB group with rates of 3.8% versus 1.8% (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001) for mechanical complications and 1.7% versus 0.6% (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001) for any other complications, respectively. The overall revision rate for the study population was 4.4% (234/5,377). The revision rates of cemented and uncemented systems were similar (\u003cem\u003eP\u003c/em\u003e = 0.832). However, the revision rate of MB UKA was significantly higher than that of FB designs (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001).\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of complication rates in Türkiye according to hospital types.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHospital type\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eComplication rates (%)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ep values\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eState University Hospitals\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37/1039 (3.6%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt; 0.01\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePrivate University Hospitals\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22/386 (5.7%)\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePrivate Hospitals\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e191/2526 (7.6%)\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eState Hospital \u0026amp; Training Hospitals\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e225/4636 (4.9%)\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003e\u003cem\u003ea: Pearson Chi-square test.\u003c/em\u003e\u003c/p\u003e \u003cp\u003e\u003cem\u003eIn subgroup analysis, a significant difference was found between state university hospitals and private hospitals (p \u0026lt; 0.01).\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of patients’ demographics according to occurrence of complications\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePatients without Complications\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePatients with \u003c/p\u003e \u003cp\u003eComplications\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep value\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (Years)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8590\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59 ± 8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e59 ± 9\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.869\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex (Women/Men)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8590\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6907(85%) /1208(15%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e408(86%) / 67(14%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.690\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWeight (kg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3378\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e82 ± 13\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e83 ± 15\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.161\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3378\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32 ± 5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32 ± 5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.605\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInsert type (Mobile/Fixed)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5377\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2617(51%) / 2498(49%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e181(69%)/81(31%)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt; 0.001\u003c/b\u003e\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eType of fixation \u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(Uncemented/ Cemented/ Hybrid)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5377\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1120/3938/57\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e65/190/7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.035\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eBMI: Body mass index, n: Number of patients\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003csup\u003ea\u003c/sup\u003e: Independent sample t test, \u003csup\u003eb\u003c/sup\u003e: Fisher exact test, \u003csup\u003ec\u003c/sup\u003e: Pearson Chi-square test\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003ch2\u003ePostoperative Mortality Rates\u003c/h2\u003e\u003cp\u003eThe overall mortality rate was \u0026lt; 0.1% (1/8,590) in the first 10 days after the primary surgery and \u0026lt; 0.1% (3/8,590) in the first postoperative month, and \u0026lt; 0.1% (6/8,590) of the patients had died at the final follow-up. The mean time from index operation to death was 37 ± 24 days (range, 3–62).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe most important finding of this study was that complication rates were significantly higher among patients treated with MB implants compared to FB implants. This might be one of the reasons for the increased utilization of FB over time, from 18% at the beginning of the study period to 74% after 2018. However, we found no significant difference in complication rates between cemented and cementless UKAs. In addition, there were significantly fewer complications in state university hospitals, where UKA was performed more frequently, compared to private hospitals.\u003c/p\u003e \u003cp\u003eThis is the first nationwide study analyzing prospectively collected data of the Turkish Ministry of Health about UKA. In T\u0026uuml;rkiye, the majority of patients are reimbursed by the public insurance system and registration in the database of the Turkish Ministry of Health is mandatory. Therefore, this cohort is representative of more than 90% of the UKA surgeries performed in the country. Although there are some limitations to the types of data available, we were able to analyze revision rates and subtypes of complications as mechanical or septic. Trends in design and fixation preferences over the years were observed and geographical data could be correlated with outcomes.\u003c/p\u003e \u003cp\u003eSimilar to our results, many comparative studies in the literature have demonstrated that cementless UKA is a safe option and has comparable, if not better, interim results compared to cemented fixation [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Mancino et al reported that the revision rate for cemented UKA was significantly higher (10.2% at 5.7-year follow-up) than that of cementless fixation (5.8% at 4.1-year follow-up in 4,776 patients) [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. A systematic review by Mohammad et al showed that the annual revision rate of cementless UKA was almost two-thirds that of cemented UKA [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Data from the New Zealand Joint Registry (NZJR) including 1,473 revisions of 16,890 registered UKAs reported that the revision rate of cementless UKA (304/6,781) was significantly lower than that of cemented implants (1,106/9,382) [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Similar to the NZJR, data from the British National Joint Registry (NJR) on the cumulative revision rates of 103,385 cemented and 33,508 cementless UKAs revealed that the revision rate for cementless implants was lower than that for cemented UKAs (5.4% vs. 3.7% at 5 years and 10% vs. 7.4% at 10 years) [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The reasons for revisions for cemented UKAs were the progression of osteoarthritis, aseptic loosening, and pain. For the uncemented group, the most common reason was instability rather than pain. The incidences of revisions for pain and aseptic loosening were lower for cementless UKAs compared to cemented fixation. A Dutch database from 2022, which included 32,276 UKAs, showed that the usage of cemented UKA decreased from 80% to less than 40% from 2012 to 2021. The cumulative revision rate of cemented UKA was found to be higher than that of cementless UKA (8% vs. 5% at 5 years and 12% vs. 8% at 10 years) [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The 2021 Annual Report of the Swedish Arthroplasty Register noted that before 2010 almost all UKAs were cemented but after 2013 this changed. In 2020, 58.5% of UKAs were cementless and 1.1% used hybrid fixation; this increase was due to the popularity of Oxford implants, 94% of which were uncemented [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. In our study, 4,128 of 5,313 patients underwent cemented UKA between 2016 and 2022. Cemented fixation continues to be used more frequently since 2012. We found that the rate and type of complications were similar between cemented and cementless fixation. Interestingly, the complication rate was significantly higher in the fully cemented fixation group compared to hybrid fixation (11% vs. 5%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01).\u003c/p\u003e \u003cp\u003eThe MB and FB UKA designs have specific advantages and shortcomings. The MB design has a large contact area and has become popular for minimizing polyethylene contact stress and wear [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. This theoretically reduces the risk of long-term aseptic loosening, polyethylene wear, and implant revision by providing less contact stress and more compatible bearing surfaces with large contact areas. On the other hand, a lack of precise alignment and ligament balancing can cause bearings to dislodge or warp, resulting in increased wear [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Furthermore, MB UKA is considered to be technically demanding due to difficulties in balancing the knee [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In contrast, FB designs are less technically demanding and insert dislocation is not an issue. However, the flat and less conforming design may lead to earlier polyethylene wear compared to mobile designs due to decreased contact area and increased contact pressure [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Conflicting outcomes have been reported in the literature regarding insert type, and debate continues as to which prosthetic design has superior long-term outcomes [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Zhang et al published a meta-analysis of 17 studies including 2,612 knees comparing MB and FB designs and found no difference in radiological and clinical outcomes, revision rates, or survivorship [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In another meta-analysis, Migliorini et al collected data from 25 studies of 4,696 patients and reported no difference in functional outcomes, complications, or implant survivorship between bearing types [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The 2022 German Arthroplasty Registry Report compared the revision rates of 26,033 MB and 16,866 FB procedures [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The revision rates were found to be similar at both 5 years (7.1% vs. 7.5%) and 7 years (7.8% vs. 8.6%). However, MBs were utilized less frequently in 2022; the percentage was only 53.8% compared to 71.6% in 2014. The Australian Orthopaedic Association\u0026rsquo;s National Joint Replacement Registry reported the outcomes of 22,229 MB and 23,193 FB procedures in 2021 and MB implants from two different manufacturers in this registry had an increased risk of revision for both medial and lateral UKAs [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The cumulative percent revision rates of UKAs were 5.2% versus 7.6% at 5 years and 9.3% versus 13.8% at 10 years for FB and MB designs, respectively. The NJR, including data from all participating hospitals in England, Wales, Northern Ireland, the Isle of Man, and Guernsey, compared 82,117 MB and 57,767 FB designs [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The 5-year Kaplan-Meier estimates of the cumulative revision rates for cemented and cementless FB designs were 3.8% and 5.3%, and for MB designs they were 6.4% and 3.6%, respectively. In the current study, the rate of complications was found to be significantly higher for MB compared to FB designs as overall (6% vs. 3%), mechanical (4% vs. 2%), and other complications (2% vs. \u0026lt;1%) were all higher among patients who had received MB implants. The revision rate for MB implants was also significantly higher (6% vs. 2%).\u003c/p\u003e \u003cp\u003eIt is widely accepted that UKA has higher complication and revision rates compared to TKA [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The 2022 German Arthroplasty Registry Annual Report revealed that the revision probability of UKA was almost twice that of TKA and its cumulative revision rate at 5 years was as high as 7%. Centers performing fewer than 30 UKAs annually had a cumulative revision rate of more than twice that of centers performing more than 100 UKAs [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. This negative correlation between surgical volume and complications and revision rates in UKA is important. Higher patient volume has been shown to reduce the risk of revision [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. In a study using NJR data, revision rates reached acceptable levels when the surgeons performed UKAs in at least 20% of their overall knee arthroplasty caseloads [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. That study found optimum outcomes when the surgeon\u0026rsquo;s UKA usage was between 40% and 60%; more importantly, surgeons with UKA caseloads of \u0026lt;\u0026thinsp;5% had the highest revision rates [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. In another study, Murray et al showed that a minimum yearly caseload of 12 UKAs significantly decreased the revision rate [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Klasan et al analyzed 131,575 UKAs from the UK, Australian, and New Zealand registries and classified surgeons according to their surgical volumes. Surprisingly, more than 50% of the knee surgeons in each registry had a proportion of less than 5% UKA compared to TKA in clinical practice [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Although surgical volumes of the surgeons and hospitals were not analyzed in our study, the complication and revision rates of UKA were found to be significantly lower in state university hospitals in T\u0026uuml;rkiye, where UKA is applied more frequently compared to private institutions.\u003c/p\u003e \u003cp\u003eThis study had several limitations. The data were collected from a national database and potential errors in data input from hospitals on the etiology of arthritis, patient demographics, and comorbidities might have produced a bias. No data were available on the type of UKA; therefore, distinctions between medial, lateral, and bicompartmental arthroplasties could not be made. Patient-reported outcome measures were not recorded in the database. Complications were classified as \u0026ldquo;mechanical,\u0026rdquo; \u0026ldquo;infection,\u0026rdquo; and \u0026ldquo;others\u0026rdquo; and no data were available on the number of patients who had aseptic loosening, insert dislocation, periprosthetic fracture, collapse, or disease progression. Data on the implant manufacturer were available in only a limited number of cases; therefore, Kaplan-Meier survivorship analysis could not be performed for specific implants. The strength of this study is that it provided an accurate overview of the current situation in T\u0026uuml;rkiye, covering more than 90% of the procedures performed in the country due to the mandatory nature of the registry. Future work will focus on improving the database while keeping the above-mentioned shortcomings in mind.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study has presented the registry data of the Ministry of Health of T\u0026uuml;rkiye, constituting the largest patient volume of UKA in the country. The majority of the UKAs in T\u0026uuml;rkiye were performed as cemented implants with an increased usage of fixed bearings over time. Mobile-bearing designs had significantly greater complication and revision rates compared to fixed-bearing implants. These results may help orthopaedic surgeons in decision-making processes for the treatment of knee osteoarthritis. We hope that our results will raise the awareness of health care authorities regarding the importance of implant registries and lead to improvements in data collection and analysis.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Generative AI and AI-assisted technologies in the writing process\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDuring the preparation of this work the authors used ChatGPT in order to edit the language quality and grammer of the text.\u0026nbsp;\u003cbr\u003e\u0026nbsp;\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eA.P. and F.Y. wrote the manuscript\u0026Ouml;.S.H. made the statistical analysisM.B. prepared the tables and figuresB.A., İ.B., İ.A., R.T., İ.T., made suggestions and corrections for the manuscriptN.A., M.M.\u0026Uuml;., Ş.B., M.O.A., provided and sorted the data, made the data clearer for the analysis\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCarr AJ, Robertsson O, Graves S, Price AJ, Arden NK, Judge A et al (2012) Knee replacement. 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Clin Orthop Relat Res 452:137\u0026ndash;142. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/01.blo.0000229358.19867.60\u003c/span\u003e\u003cspan address=\"10.1097/01.blo.0000229358.19867.60\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang W, Wang J, Li H, Wang W, George DM, Huang T (2020) Fixed- versus mobile-bearing unicompartmental knee arthroplasty: a meta-analysis. 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Knee Surg Sports Traumatol Arthrosc 20:1042\u0026ndash;1048. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00167-011-1620-z\u003c/span\u003e\u003cspan address=\"10.1007/s00167-011-1620-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMigliorini F, Maffulli N, Cuozzo F, Elsner K, Hildebrand F, Eschweiler J et al (2022) Mobile bearing versus fixed bearing for unicompartmental arthroplasty in monocompartmental osteoarthritis of the knee: a meta-analysis. J Clin Med 11:2837. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/jcm11102837\u003c/span\u003e\u003cspan address=\"10.3390/jcm11102837\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGerman Arthroplasty Registry (EPRD). EPRD Annual Report 2022. 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Bone Joint J 97:1506\u0026ndash;1511. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1302/0301-620X.97B11.35551\u003c/span\u003e\u003cspan address=\"10.1302/0301-620X.97B11.35551\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMurray D, Parkinson R (2018) Usage of unicompartmental knee arthroplasty. Bone Joint J 100:432\u0026ndash;435. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1302/0301-620X.100B4.BJJ-2017-0716.R1\u003c/span\u003e\u003cspan address=\"10.1302/0301-620X.100B4.BJJ-2017-0716.R1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKlasan A, Parker DA, Lewis PL, Young SW (2022) Low percentage of surgeons meet the minimum recommended unicompartmental knee arthroplasty usage thresholds: analysis of 3037 surgeons from three national joint registries. Knee Surg Sports Traumatol Arthrosc 30:958\u0026ndash;964. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00167-021-06437-7\u003c/span\u003e\u003cspan address=\"10.1007/s00167-021-06437-7\" 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":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"international-orthopaedics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [International Orthopaedics](https://link.springer.com/journal/264)","snPcode":"264","submissionUrl":"https://submission.springernature.com/new-submission/264/3","title":"International Orthopaedics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Unicondylar knee arthroplasty, fixation, complication, type of insert, survivorship","lastPublishedDoi":"10.21203/rs.3.rs-8640066/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8640066/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eFavorable long-term clinical and radiological outcomes with low revision and reoperation rates have been reported for unicondylar knee arthroplasty (UKA) in the treatment of end-stage unicompartmental knee osteoarthritis. However, no information on these data is available for the Turkish population. Our aim was to analyze the demographics, indications, outcomes, and revision rates of UKA in T\u0026uuml;rkiye using a nationwide database.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThe electronic medical records of 8,590 patients undergoing UKA for unicompartmental osteoarthritis between 2016 and 2022 were retrospectively analyzed. Demographic data of the study population including sex, age, body mass index (BMI), and institution were assessed. The primary outcome measures were complication and revision rates.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOf the 8,590 analyzed patients, 85.2% were women with an average age of 59\u0026thinsp;\u0026plusmn;\u0026thinsp;8 years. The primary indication was osteoarthritis in 7,205 (94.1%) cases. Most patients received cemented implants (78% vs. 22%) and the use of fixed insert designs increased from 18% to 74% between 2018 and 2022. The overall complication rate for the study population was 5.5% (475/8,590). The rate of complications did not differ according to fixation type. However, it was statistically significantly higher in patients who received mobile UKA than the fixed design (3.8% vs. 1.8% for mechanical complications and 1.7% vs. 0.6% for other complications, respectively; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The overall revision rate was 4.4% (234/5,377), with rates being similar for cemented and cementless designs (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.832). However, the revision rate of mobile UKA was significantly higher than that of fixed designs (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe majority of UKAs in T\u0026uuml;rkiye were cemented implants with an increased usage of fixed bearings over time. Mobile-bearing designs had significantly greater complication and revision rates compared to fixed-bearing implants.\u003c/p\u003e","manuscriptTitle":"Demographics and Outcomes of Unicondylar Knee Arthroplasty in Türkiye: A Nationwide Retrospective Database Study of 8590 Cases","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-02 09:42:48","doi":"10.21203/rs.3.rs-8640066/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-30T19:40:08+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-30T18:02:45+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"277999401400386937951430190398091378720","date":"2026-01-30T17:39:58+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-29T15:12:54+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-28T18:39:25+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-28T18:39:11+00:00","index":"","fulltext":""},{"type":"submitted","content":"International Orthopaedics","date":"2026-01-19T13:33:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"international-orthopaedics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [International Orthopaedics](https://link.springer.com/journal/264)","snPcode":"264","submissionUrl":"https://submission.springernature.com/new-submission/264/3","title":"International Orthopaedics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"9ded6fbe-030d-4cab-8ac4-c5a2a55be702","owner":[],"postedDate":"February 2nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-27T18:38:39+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-02 09:42:48","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8640066","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8640066","identity":"rs-8640066","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}