Skip to main content

A comparative study of 21,194 UKAs and 49,270 HTOs for the risk of unanticipated events in mid-age patients from the national claims data in South Korea



Both high tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) are well-established treatments for medial knee osteoarthritis (OA). However, over the past 20 years, results of comparisons of long-term survival rates and outcomes have remained controversial. Furthermore, in patients at the boundary age, from 50 to 70 years, considering age as a treatment indication, selecting a surgical method is difficult. Therefore, we aimed to investigate conversion rates to total knee arthroplasty (TKA) and perioperative adverse outcomes between the two surgical methods in mid-age patients.


We extracted data from the Korean National Health Insurance claims database. A total of 70,464 patients aged between 50 and 70 years, considered as mid-age patients were included in the final study population. We used a multivariable Cox proportional hazard regression model, adjusting for potential confounders such as age, sex, insurance type, region of residence, hospital type, comorbidities, and the Charlson comorbidity Index (CCI).


Of the 70,464 patients, 21,194 were treated with UKA and 49,270 were treated with HTO. HTO showed a higher risk of revision than UKA at five, and 10 years and during the whole observation period. The incidence of deep vein thromboembolism, and surgical site infection was significantly higher in UKA than in HTO.


It is important to choose an appropriate surgical method considering that UKA has better results in terms of long-term survival rates but may have a higher incidence of various complications.

Peer Review reports


Most patients with knee osteoarthritis(OA) have lesions limited to the medial compartment, and high tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) are well-established treatments for this condition [1,2,3]. HTO and UKA, which are often performed as primary surgeries in medial knee OA, report good results as the ultimate treatment for OA with an added advantage of delaying conversion to total knee arthroplasty (TKA) [4, 5]. However, to date, considering which of the two surgical methods to choose remains controversial, comparing long-term survival rates and surgical outcomes [6,7,8] In particular, when selecting a surgical method for patients in their 50 s and 60 s, there are many considerations. [3, 9,10,11]. Both HTO and UKA have the advantage of saving native joint spaces, but there are some differences in surgical techniques and indications. HTO is considered primarily in young and active patients, and has the advantage of preserving the native knee compartment by correcting malalignment of the lower extremity and shifting the axis of the weight load to the lateral compartment [6, 12]. Good results have been reported for UKA in relatively elderly patients with less physical requirements, by replacing only the medial compartment in which the arthritic change was progressing [13]. Due to factors such as improvement of surgical methods and implants, surgical indications between the two operations have overlapped [6, 14]. In addition to age and physical demand, the relative merits of the two surgical methods are unclear and are still controversial which lead a lack of clear criteria for selecting a surgical method [6]. Numerous studies have compared the advantages and clinical results between the surgical methods, and the superiority of one over the other has not been proven [1,2,3,4,5,6,7,8, 12,13,14]. Therefore, the objectives of this study are as follows: (1) to evaluate revision rates of the two surgical methods and (2) analyze the outcomes in terms of perioperative complications. It was hypothesized that there is no difference between HTO and UKA with regard to survival and complication rates because both treatments are well established treatment methods.


Data sources

This study was conducted using data from the Korea National Health Insurance Review and Assessment Service. Korea's health insurance system is considered well-established worldwide, with almost 99% of the population enrolled [15]. The Korean health insurance claim data uses the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes and Electronic Data Interchange (EDI) codes, which are internationally accepted classifications for diagnosis and procedures. Information such as patient's age, gender, diagnosis, hospitalization record, surgery record, drug prescription, and hospital area information is provided in an anonymous form, and the individual data linked to each code are recorded in the NHI database in Korea. Data were obtained from January 2008 to May 31 2019. All medical records have been provided for patients diagnosed with osteoarthritis of the knee joint and having undergone surgical treatments.

Study approval

This study was approved by the Institutional Review Board of Chonnam National University Hwasun Hospital. The review board waived the requirement for patient consent considering the characteristics of this study.

Data collection

The diagnostic code for knee OA (M17) and procedure codes for UKA (N2712, N2717) or HTO (N0304) were used to extract patients who had undergone UKA or HTO for the treatment of knee OA. Patients under 50 years of age and over 70 years of age were excluded for analysis of middle-aged participants. An effort was made to extract newly diagnosed and operated patients within a defined study period by applying a 1-year wash-out period for knee arthritis and surgical treatment history (Fig. 1). We compared UKA and HTO in terms of conversion to primary TKA, incidence of unanticipated major medical problems, Intensive Care Unit (ICU) admission, postoperative transfusion, and readmission rates. Patient demographic data were extracted using the aforementioned diagnostic code and each surgical code and included age, sex, type of insurance, hospital, region of residence, and medical comorbidities (Table 1). By using the Korean claim data, it was not possible to distinguish between medial open wedge osteotomy and lateral closed wedge osteotomy of HTO and the type of implant. The type of hospital was classified as a teaching hospital(> 500 beds), a general hospital(30–500 beds), an independent hospital(< 30beds), and a private clinic(outpatient clinic). The region of residence was classified, based on population, as cities with a population of 10 million or more(e.g., Seoul), cities with a population of 1 million or more(eg, Busan, Incheon, Daegu, Gwangju, Daejeon and Ulsan), and cities with a population of less than 1 million(Gyeonggi, Gangwon, Gyeongsangbuk, Gyeongsangnam, Chungcheongbuk, Chungcheongnam, Jeollabuk, Jeollanam and Jeju). Medical comorbidities (hypertension, diabetes mellitus, hyperlipidemia, osteoporosis, peripheral vascular disease, depression and dementia) were confirmed based on the ICD-10 diagnostic codes with at least two claims within 1 year from the date of surgery. The Charlson comorbidity index (CCI) score was calculated from the ICD-10 codes by introducing previous literature methods. Statistical analysis was performed to consider as many adjusted variables as possible to address the imbalance of basic patient characteristics between the two groups.

Fig. 1
figure 1

Flowchart for target population

Table 1 Patient baseline characteristics in 50–69 aged patients

Statistical analysis

The baseline characteristics of patients treated with HTO or UKA were summarized using descriptive statistics, including proportion, mean, and standard deviation. Differences between UKA and HTO in continuous variables were evaluated with analysis of variance and categorical variables were compared using the Chi-square test. Wilcoxon statistic assigned a greater weight to differences occurring near the beginning of the study. The imbalance in baseline characteristics between the two groups was evaluated with standardized mean difference (SMD). An SMD of less than 0.1 was considered a negligible difference between the groups. Covariants with an SMD greater than 0.1 were corrected by setting them as adjusting variables. The person-years (PY) for each group of patients were calculated from the date of primary surgery to the event of subsequent revision and various adverse outcomes. We conducted a stratified log-rank test and obtained Kaplan–Meier curves considering potential confounders. In addition, conditional logistic and stratified Cox regression analyses were conducted to calculate complication rates. The adjusted hazard ratio (HR) and 95% confidence interval (CI) were calculated using a multivariable Cox proportional hazard regression model adjusting for potential confounders such as age, sex, insurance type, region of residence, hospital type, comorbidities, and the CCI. All statistical analyses were performed using R software (version 3.4.1; R Foundation for Statistical Computing) and SAS Enterprise software (version 6.1; SAS Institute).


According to the data extracted through Korea's Health Insurance Review and Assessment Service from January 2007 to May 31, 2019, a total of 78,448 patients aged 50 to 70 who underwent UKA or HTO were recorded. Considering the one-year wash-out period, 6,910 patients with surgical records before 2008 and after 2018 were excluded, and 1,074 patients with inappropriate claims data were eliminated, therefore, 70,464 patients were included as the final study subjects, of which 21,194 were in the UKA group and 49,270 in the HTO group (Fig. 1). The mean age of the patients was 60.4 years in the UKA group and 57.8 years in the HTO group, meanwhile, the proportion of women in both groups was remarkably high. Both treatments showed an increase in the number of surgeries over the years, and in terms of underlying disease characteristics, hypertension, diabetes, and osteoporosis were more common in the UKA group, which had a higher average age (Table 1).

There were no significant differences in an unadjusted analysis when comparing the risk of requiring revision between the two groups (Table 2). The Kaplan–Meier survivorship curve showed no significant difference between UKA and HTO (p = 0.92) (Fig. 2A), and in the survival rate in the HTO group according to sex (p = 0.16) (Fig. 2B), but in the UKA group, the survival rate was higher in male patients than in female patients (p < 0.001) (Fig. 2C).

Table 2 COX proportional hazard survival analysis for risk of revision for 50–69 aged patients
Fig. 2
figure 2

Kaplan–Meier survivorship curve: 11.5-year survival probability of total patients (A), gender differences in HTO (B), gender differences in UKA (C)

An adjusted analysis considering baseline characteristics such as age, sex, comorbidities, insurance type, hospital size, residence, and the CCI, showed that the risk of requiring revision in HTO was higher than that in UKA (HR: 1.19, 95% CI: 1.11–1.27) (Table 2). The HRs were 1.17 (1.07–1.27) at 5 years and 1.18 (1.10–1.26) at 10 years. A Cox proportional hazard analysis revealed that the incidence of deep vein thromboembolism (DVT) (HR: 0.33, 95% CI: 0.28–0.39), and surgical site infection (HR: 0.40, 95% CI: 0.35–0.46) was significantly higher in UKA than in HTO (Table 3). Other adverse outcomes, including pulmonary thromboembolism, cerebrovascular disease, myocardial infarction, postoperative delirium, and acute renal failure (ARF), showed no significant differences. In terms of perioperative complications, the incidence of postoperative ICU admission was significantly higher in UKA (OR: 0.21, 95% CI: 0.15–0.29), while that of re-hospitalization within 30 days (OR: 1.28, 95% CI: 1.18–1.38) and 90 days (OR: 1.28, 95% CI: 1.22–1.34) was higher in HTO (Table 4).

Table 3 COX proportional hazard analysis for adverse outcomes
Table 4 Logistic regression analysis for perioperative complications


We identified 78,448 patients who underwent UKA or HTO, to evaluate the results regarding the revision rate and postoperative complications relevant to each treatment. Throughout the total observation period of 11.5 years, the survival rate after UKA was significantly higher than that after HTO. In addition, when comparing the risk of complications after surgery, some significant differences were found between the two surgeries. Notably, the incidences of postoperative DVT and surgical site infection were higher in UKA than in HTO.

In previous studies on the survival rates of HTO and UKA, different results have been reported over the past 20 years. Some reported that UKA had better long-term survival rates compared to HTO [8, 16]. On the contrary, other studies showed better results for HTO [17], meanwhile, other studies concluded that there were no significant differences [5, 6, 13]. However, most of the previous comparison studies consisted of different patient characteristics, and short retrospective or small randomized controlled studies. In the present study, the long-term survival rate was analyzed, with adequate power and using adjusted covariates, and the risk of revision was compared at different time points, that is at 5 and 10 years.

In terms of postoperative complications, various results are reported in the literature. Some researchers reported that UKA is superior to HTO in terms of postoperative function and has fewer complications [6, 13, 18, 19], while others reported little differences between the two treatments [4, 14, 20]. However, to the best of our knowledge, the incidence of the major postoperative medical complications such as pulmonary, cerebrovascular and cardiac problems has not been compared between HTO and UKA, unlike a study exists in TKA and UKA [21]. We found no significant difference between the two surgeries in most complication rates, meanwhile, significant differences were found in the incidence of DVT and surgical site infection. The HTO group showed significantly low infection rate, which may be related to a relatively short operation time [22,23,24] and showed low risk of DVT possibly due to routine usage of mechanical compression after surgery [25], and pharmacologic prophylaxis [26]. There have been previous studies on factors related to ARF after orthopedic surgery, but studies related to different surgical methods, especially artificial joint surgery, have been insufficient and may require further evaluation [27, 28]. On the other hand, cemented knee arthroplasty, as one of the independent risk factors for postoperative ICU admission in some studies could relate that the result of higher ICU admission in UKA as shown in Table 4 [29, 30]. HTO often requires a more dependent functional status postoperatively compared to UKA, which may be a reason for higher re-hospitalization in HTO [2, 7, 31, 32].

In this study, the survival rate and complications of UKA and HTO were analyzed for mid-aged patients, but as the indications of UKA and HTO widened and overlapped [33,34,35], there are many reports of good results obtained by performing UKA and HTO in a younger patient group [10, 11]. However, there are still studies showing that the risk of early conversion to TKA increases as the patient's age increases [9, 34, 36]. In contrast, Other studies concluded that the relationship between age and implant survival and clinical outcome is not significant [35, 37,38,39]. they suggest that UKA and HTO should be performed regardless of age. Elderly or young age should not be a contraindication for selecting surgical methods [35, 37,38,39].

The strength of our study is the use of Korea's health insurance system which covers up to 99% of the entire population [15]. Using strict statistical analysis to reduce potential confounders, we carried out a long-term, large-scale population-based comparison study. However, this study had several limitations. First, the national registry data have inherent problems, including inaccurate diagnostic codes and lack of detailed medical records (e.g., type of inserted implants, different surgical techniques, and causes for revision surgery). Second, we could not identify the consecutive values such as body mass index, degree of leg deformity, and osteoarthritis stage. Furthermore, other clinical outcomes, including functional and radiological indicators were not provided. Third, the claim code of the health insurance claim data could not distinguish between the left and right side of the knee joint on which the procedure was done. Thus, patients who underwent the first knee replacement were defined when selecting subjects to analyze the comparative effects. The analysis included only those patients for whom there was only one claim for 'HTO or UKA' in the claim data, and the analysis excluded patients with two or more claims at different times because the exposure time could not be defined. Fourth, the maximum follow-up period in this study was 11.5 years which could be extended in future studies. In addition, there may be differences due to race and national differences compared to other countries. Despite these limitations, the authors believe that the current study is worthy because it is the first large-scale, long-term cohort study with patients of a specific age category, which is the boundary between the indications for the two surgeries.


It is important to choose an appropriate surgical method for unicompartmental knee OA considering that UKA has better results in terms of long-term survival rates, but may have a higher incidence of various complications even considering the high prevalence of underlying diseases in the UKA group in the preoperative patient characteristics.

Availability of data and materials

The public access to the database is closed. Access to the database is granted only to researchers approved by the Korea Health Insurance Review and Assessment Service. All data is anonymized and encrypted to protect personal information, but external disclosure is prohibited in principle. Dataset: de-identified datasets generated and analysed during the present study will be made available by request from the Health Insurance & Assessment Service of Korea at After user approaval by the Health Insurance Review and Assessment Service, a remote analysis system ( can be used by receiving a virtualized ID.



Total knee arthroplasty


Unicompartmental knee arthroplasty


High tibial osteotomy




Charlson comorbidity index


International statistical classification of diseases and related Health Problems


Electronic data interchange


Intensive care unit


Standardized mean difference


Propensity score matching




Hazard ratio


Confidence interval


Deep vein thromboembolism


  1. Jacquet C, Gulagaci F, Schmidt A, Pendse A, Parratte S, Argenson JN, Ollivier M. Opening wedge high tibial osteotomy allows better outcomes than unicompartmental knee arthroplasty in patients expecting to return to impact sports. Knee Surg Sports Traumatol Arthrosc. 2020;28(12):3849–57.

    Article  PubMed  Google Scholar 

  2. Petersen W, Metzlaff S. Open wedge high tibial osteotomy (HTO) versus mobile bearing unicondylar medial joint replacement: five years results. Arch Orthop Trauma Surg. 2016;136(7):983–9.

    Article  PubMed  Google Scholar 

  3. Ziqi Z, Yufeng M, Lei Z, Chunsheng W, Pei Y, Kunzheng W. Therapeutic effects comparison and revision case analysis of unicompartmental knee arthroplasty and open wedge high tibial osteotomy in treating medial knee osteoarthritis in patients under 60 years: A 2–6-year follow-up study. Orthop Surg. 2020;12(6):1635–43.

    Article  PubMed  PubMed Central  Google Scholar 

  4. Takeuchi R, Umemoto Y, Aratake M, Bito H, Saito I, Kumagai K, Sasaki Y, Akamatsu Y, Ishikawa H, Koshino T, Saito T. A mid term comparison of open wedge high tibial osteotomy vs unicompartmental knee arthroplasty for medial compartment osteoarthritis of the knee. J Orthop Surg Res. 2010;5(1):65.

    Article  PubMed  PubMed Central  Google Scholar 

  5. Song SJ, Bae DK, Kim KI, Park CH. Long-term survival is similar between closed-wedge high tibial osteotomy and unicompartmental knee arthroplasty in patients with similar demographics. Knee Surg Sports Traumatol Arthrosc. 2019;27(4):1310–9.

    Article  PubMed  Google Scholar 

  6. Santoso MB, Wu L. Unicompartmental knee arthroplasty, is it superior to high tibial osteotomy in treating unicompartmental osteoarthritis? A meta-analysis and systemic review. J Orthop Surg Res. 2017;12(1):50.

    Article  PubMed  PubMed Central  Google Scholar 

  7. Kim MS, Koh IJ, Sohn S, Jeong JH, In Y. Unicompartmental knee arthroplasty is superior to high tibial osteotomy in post-operative recovery and participation in recreational and sports activities. Int Orthop. 2019;43(11):2493–501.

    Article  PubMed  Google Scholar 

  8. Cao Z, Mai X, Wang J, Feng E, Huang Y. Unicompartmental Knee Arthroplasty vs High Tibial Osteotomy for Knee Osteoarthritis: A Systematic Review and Meta-Analysis. J Arthroplasty. 2018;33(3):952–9.

    Article  PubMed  Google Scholar 

  9. Wd A, Robertsson O, Lidgren L, Miller L, Davidson D, Graves S. Unicompartmental knee arthroplasty in patients aged less than 65. Acta Orthop. 2010;81(1):90–4.

    Article  Google Scholar 

  10. Greco NJ, Lombardi AV Jr, Price AJ, Berend ME, Berend KR. Medial Mobile-Bearing Unicompartmental Knee Arthroplasty in Young Patients Aged Less Than or Equal to 50 Years. J Arthroplasty. 2018;33(8):2435–9.

    Article  PubMed  Google Scholar 

  11. Wang F, Xue H, Ma T, Wen T, Yang T, Xue L, Tu Y. Short-term effectiveness of medial unicompartmental knee arthroplasty in young patients aged less than or equal to 60 years. J Orthop Surg (Hong Kong). 2020;28(3):2309499020945118.

    Article  Google Scholar 

  12. Smith WB 2nd, Steinberg J, Scholtes S, McNamara IR. Medial compartment knee osteoarthritis: age-stratified cost-effectiveness of total knee arthroplasty, unicompartmental knee arthroplasty, and high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc. 2017;25(3):924–33.

    Article  PubMed  Google Scholar 

  13. Han SB, Kyung HS, Seo IW, Shin YS. Better clinical outcomes after unicompartmental knee arthroplasty when comparing with high tibial osteotomy. Medicine (Baltimore). 2017;96(50): e9268.

    Article  Google Scholar 

  14. Jeon YS, Ahn CH, Kim MK. Comparison of HTO with articular cartilage surgery and UKA in unicompartmental OA. J Orthop Surg (Hong Kong). 2017;25(1):2309499016684092.

    Article  Google Scholar 

  15. Kim JA, Yoon S, Kim LY, Kim DS. Towards Actualizing the Value Potential of Korea Health Insurance Review and Assessment (HIRA) Data as a Resource for Health Research: Strengths, Limitations, Applications, and Strategies for Optimal Use of HIRA Data. J Korean Med Sci. 2017;32(5):718–28.

    Article  PubMed  PubMed Central  Google Scholar 

  16. Rodriguez-Merchan EC. Unicompartmental Knee Osteoarthritis (UKOA): Unicompartmental Knee Arthroplasty (UKA) or High Tibial Osteotomy (HTO)? Arch Bone Jt Surg. 2016;4(4):307–13.

    PubMed  PubMed Central  Google Scholar 

  17. Krych AJ, Reardon P, Sousa P, Pareek A, Stuart M, Pagnano M. Unicompartmental Knee Arthroplasty Provides Higher Activity and Durability Than Valgus-Producing Proximal Tibial Osteotomy at 5 to 7 Years. J Bone Joint Surg Am. 2017;99(2):113–22.

    Article  PubMed  Google Scholar 

  18. Cho WJ, Kim JM, Kim WK, Kim DE, Kim NK, Bin SI. Mobile-bearing unicompartmental knee arthroplasty in old-aged patients demonstrates superior short-term clinical outcomes to open-wedge high tibial osteotomy in middle-aged patients with advanced isolated medial osteoarthritis. Int Orthop. 2018;42(10):2357–63.

    Article  PubMed  Google Scholar 

  19. Fu D, Li G, Chen K, Zhao Y, Hua Y, Cai Z. Comparison of high tibial osteotomy and unicompartmental knee arthroplasty in the treatment of unicompartmental osteoarthritis: a meta-analysis. J Arthroplasty. 2013;28(5):759–65.

    Article  PubMed  Google Scholar 

  20. Yim JH, Song EK, Seo HY, Kim MS, Seon JK. Comparison of high tibial osteotomy and unicompartmental knee arthroplasty at a minimum follow-up of 3 years. J Arthroplasty. 2013;28(2):243–7.

    Article  PubMed  Google Scholar 

  21. Liddle AD, Judge A, Pandit H, Murray DW. Adverse outcomes after total and unicompartmental knee replacement in 101,330 matched patients: a study of data from the National Joint Registry for England and Wales. Lancet. 2014;18;384(9952):1437–45.

    Article  Google Scholar 

  22. Wang Q, Goswami K, Shohat N, Aalirezaie A, Manrique J, Parvizi J. Longer Operative Time Results in a Higher Rate of Subsequent Periprosthetic Joint Infection in Patients Undergoing Primary Joint Arthroplasty. J Arthroplasty. 2019;34(5):947–53.

    Article  PubMed  Google Scholar 

  23. Anis HK, Sodhi N, Klika AK, Mont MA, Barsoum WK, Higuera CA, Molloy RM. Is Operative Time a Predictor for Post-Operative Infection in Primary Total Knee Arthroplasty? J Arthroplasty. 2019;34(7s):S331–6.

    Article  PubMed  Google Scholar 

  24. Schneider AM, Schmitt DR, Brown NM. Unicompartmental knee arthroplasty and revision total knee arthroplasty have a lower risk of venous thromboembolism disease at 30 days than primary total knee arthroplasty. Knee Surg Relat Res. 2020;32(1):59.

    Article  Google Scholar 

  25. Kim YH, Kulkarni SS, Park JW, Kim JS. Prevalence of Deep Vein Thrombosis and Pulmonary Embolism Treated with Mechanical Compression Device After Total Knee Arthroplasty in Asian Patients. J Arthroplasty. 2015;30(9):1633–7.

    Article  PubMed  Google Scholar 

  26. Snyder MA, Sympson AN, Scheuerman CM, Gregg JL, Hussain LR. Efficacy in Deep Vein Thrombosis Prevention With Extended Mechanical Compression Device Therapy and Prophylactic Aspirin Following Total Knee Arthroplasty: A Randomized Control Trial. J Arthroplasty. 2017;32(5):1478–82.

    Article  PubMed  Google Scholar 

  27. Bell S, Dekker FW, Vadiveloo T, Marwick C, Deshmukh H, Donnan PT, Van Diepen M. Risk of postoperative acute kidney injury in patients undergoing orthopaedic surgery development and validation of a risk score and effect of acute kidney injury on survival: observational cohort study. BMJ. 2015;351: h5639.

    Article  PubMed  PubMed Central  Google Scholar 

  28. Mavrogenis A, Mitsiokapa EA, Romantini M, Grandinetti V, Coll-Mesa L, Ruggieri P, Papagelopoulos PJ. Acute renal failure in orthopaedic surgery. J Long Term Eff Med Implants. 2011;21(2):149–58.

    Article  PubMed  Google Scholar 

  29. AbdelSalam H, Restrepo C, Tarity TD, Sangster W, Parvizi J. Predictors of intensive care unit admission after total joint arthroplasty. J Arthroplasty. 2012;27(5):720–5.

    Article  PubMed  Google Scholar 

  30. Sukhonthamarn K, Grosso MJ, Sherman MB, Restrepo C, Parvizi J. Risk Factors for Unplanned Admission to the Intensive Care Unit After Elective Total Joint Arthroplasty. J Arthroplasty. 2020;35(7):1937–40.

    Article  PubMed  Google Scholar 

  31. Zuiderbaan HA, van der List JP, Kleeblad LJ, Appelboom P, Kort NP, Pearle AD, Rademakers MV. Modern Indications, Results, and Global Trends in the Use of Unicompartmental Knee Arthroplasty and High Tibial Osteotomy in the Treatment of Isolated Medial Compartment Osteoarthritis. Am J Orthop (Belle Mead NJ). 2016;45(6):E355–61.

    Google Scholar 

  32. Oh KJ, Kim YC, Lee JS, Chang YS, Shetty GM, Nha KW. Open-wedge high tibial osteotomy versus unicompartmental knee arthroplasty: no difference in progression of patellofemoral joint arthritis. Knee Surg Sports Traumatol Arthrosc. 2017;25(3):767–72.

    Article  PubMed  Google Scholar 

  33. Malhotra R, Gupta S, Gupta V, Manhas V. Navigated Unicompartmental Knee Arthroplasty: A Different Perspective. Clin Orthop Surg. 2021;13(4):491–8.

    Article  PubMed  PubMed Central  Google Scholar 

  34. Kawaguchi K, Inui H, Taketomi S, Yamagami R, Kono K, Sameshima S, Kage T, Tanaka S. Intraoperative rotational kinematics and its influence on postoperative clinical outcomes differ according to age in Unicompartmental knee Arthroplasty. BMC Musculoskelet Disord. 2021;22(1):505.

    Article  PubMed  PubMed Central  Google Scholar 

  35. Mohammad HR, Mellon S, Judge A, Dodd C, Murray D (2021) The effect of age on the outcomes of cementless mobile bearing unicompartmental knee replacements. Knee Surg Sports Traumatol Arthrosc. Feb 12.

  36. Keenan OJF, Clement ND, Nutton R, Keating JF. Older age and female gender are independent predictors of early conversion to total knee arthroplasty after high tibial osteotomy. Knee. 2019;26(1):207–12.

    CAS  Article  PubMed  Google Scholar 

  37. Goshima K, Sawaguchi T, Sakagoshi D, Shigemoto K, Hatsuchi Y, Akahane M. Age does not affect the clinical and radiological outcomes after open-wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc. 2017;25(3):918–23.

    Article  PubMed  Google Scholar 

  38. Kohn L, Sauerschnig M, Iskansar S, Lorenz S, Meidinger G, Imhoff AB, Hinterwimmer S. Age does not influence the clinical outcome after high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc. 2013;21(1):146–51.

    CAS  Article  PubMed  Google Scholar 

  39. Lee M, Chen J, Shi LuC, Lo NN, Yeo SJ. No Differences in Outcomes Scores or Survivorship of Unicompartmental Knee Arthroplasty Between Patients Younger or Older than 55 Years of Age at Minimum 10-Year Followup. Clin Orthop Relat Res. 2019;477(6):1434–46.

    Article  PubMed  PubMed Central  Google Scholar 

Download references


We appreciate the Ministry of Health and Welfare and the Health Insurance Review & Assessment Service of Korea for sharing invaluable national health insurance claims data. The interpretation and conclusions contained in this study are those of the authors alone. Support was received from Chonnam National University Hwasun hospital.


The authors have no funding sources to report.

Author information

Authors and Affiliations



SHL, HYS, and JKS were responsible for study design. SHL and HRK take responsibility for the integrity of the data and the accuracy of the data analysis. SHL, HYS, HRK, and JKS were responsible for data interpretation. SHL and JKS prepared and edited the manuscript. The author(s) read and approved the final manuscript.

Corresponding author

Correspondence to Jong-Keun Seon.

Ethics declarations

Ethics approval and consent to participate

Institutional Review Board (IRB) of Chonnam National University Hwasun Hospital approved this study. And a formal consent is not required for this type of study.

Consent for publication

The authors agreed to publish. The consent for patients was not applicable. All patient identification codes were encrypted and anonymised by Korea National Health Insurance Review and Assessment Service to ensure confidentiality in our study.

Competing interests

The authors declare that they have no conflict of interest.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Lee, SH., Kim, HR., Seo, HY. et al. A comparative study of 21,194 UKAs and 49,270 HTOs for the risk of unanticipated events in mid-age patients from the national claims data in South Korea. BMC Musculoskelet Disord 23, 127 (2022).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI:


  • Knee
  • Osteoarthritis
  • High tibial osteotomy
  • Arthroplasty
  • Revision
  • Nationwide