Santoso and Wu Journal of Orthopaedic Surgery and Research (2017) 12:50 DOI 10.1186/s13018-017-0552-9 RESEARCHARTICLE Open Access Unicompartmental knee arthroplasty, is it superior to high tibial osteotomy in treating unicompartmental osteoarthritis? A meta-analysis and systemic review Marcel Budhi Santoso and Lidong Wu* Abstract Background: Debate remains whether high tibial osteotomy (HTO) or unicompartmental knee arthroplasty (UKA) is more beneficial for the treatment of unicompartmental knee osteoarthritis. The purpose of this study was to compare the functional results, knee scores, activity levels, and complications between the two procedures. Methods: We performed a systematic review of published literature from August 1982 through January 2017. Fifteen papers reporting three prospective randomized trials were subjected to a meta-analysis. Results: No significant difference between the two groups was noted with respect to free walking (velocity), knee score, deterioration of the contralateral or patellofemoral knee, or revision rate and total knee arthroplasty. However, UKA produced better outcomes compared to HTO in terms of the functional results, pain assessment, and complications, although patients who underwent HTO tended to have slightly better range of motion. Conclusions: Valgus HTO provides better physical activity for younger patients whereas UKA is more suitable for older patients due to shorter rehabilitation time and faster functional recovery. Although UKA patients tended to have improved overall long-term outcomes, which may be due to accurate indications and patient selection, both treatment options yielded pleasing results. Therefore, we are unable to conclude that either method is superior. Keywords: High tibial osteotomy (HTO), Unicompartmental knee arthroplasty (UKA), Osteoarthritis, Meta-analysis Background Unicompartmental knee arthroplasty (UKA) was first The management of degenerative osteoarthritis (OA) introduced in the 1970s [4] as an alternative to total aims to provide symptomatic relief and to promote knee knee arthroplasty (TKA) or HTO for single- function, which may be done conservatively or by means compartment OA. UKA is a joint resurfacing procedure of high tibial osteotomy (HTO) or knee replacement in which the affected degenerative compartment is arthroplasty. treated with an implant prosthesis, while the non- HTO is a globally recognized treatment option for medial affected compartment is preserved. UKA allows knee compartment OA of the knee, particularly for patients who bone stock preservation and offers patients a less are young and active. This procedure was first conducted in invasive procedure with a faster recovery time [5]. 1958 [1] to correct a varus deformity by lateral mechanical Studies that compare the outcomes of HTO and UKA axis relocation [2, 3]. Patients receiving HTO can benefit and their effects are lacking; thus, the relative merits of from natural joint preservation, with physical loading being the two procedures are still under debate. The aim of almost completely unaffected. this study was to evaluate both procedures for the treatment of unicompartmental knee OA using recent reports concerning the indications, functional outcomes, * Correspondence: [email protected] Department of Orthopedic Surgery, The Second Affiliated Hospital, School of complications, and subsequent revisions to TKA after Medicine, Zhejiang University, 88th Jiefang Road, Hangzhou 310009, failed HTO or UKA. Zhejiang Province, People’s Republic of China © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Santoso and Wu Journal of Orthopaedic Surgery and Research (2017) 12:50 Page 2 of 10 Methods cases where these conditions were not satisfied, a Search strategy random-effects model was adopted [6]. The present study was conducted using the Preferred The odds ratio (OR) and associated 95% confidence inter- Reporting Items for Systematic Reviews and Meta- val (CI) were used to determine the value of dichotomous Analyses (PRISMA) statement. A computerized search of data. Continuous data were evaluated by means of the stan- electronic databases (MEDLINE, Embase, and Cochrane) dardized mean difference (STD) and the corresponding for English-language studies, as well as all related published 95% CI values using the Mantel–Haenszel method [7]. full studies prior to January 2017, was performed using the In all cases, P values <0.05 were considered statistically following keywords to maximize the search sensitivity and significant. Sensitivity and subgroup analyses were specificity: “high tibial osteotomy (HTO),”“unicompart- conducted to obtain a solid conclusion and to evaluate mental knee arthroplasty (UKA),”“unicompartmental knee the stability of the results. Review Manager (RevMan) osteoarthritis,” and “high tibial osteotomy versus unicom- version 5.3 for Windows and the Cochrane collaboration partmental knee arthroplasty.” were used to interpret the relevant variables and establish the 95% CI. Inclusion and exclusion criteria All retrospective studies and prospective randomized Results studies that satisfied the search strategy were reviewed Study characteristic and were included in the present analysis if they met the A total of 1723 titles and abstracts were identified using following criteria: studies comparing the outcomes of the search strategies described above, of which 1481 HTO and UKA that clearly described at least one of the were full-text publications that were then screened based indices investigated in this analysis, articles published in on the inclusion criteria. Thirty-nine studies compared English, and cases with no previous history of knee in- HTO and UKA; however, 24 studies were excluded jury. The title and abstract were examined independently (Fig. 1). Ultimately, 15 studies [5, 8–21] were selected by two reviewers. All disagreements were resolved and included in our analysis, of which only 3 were through discussion until a consensus was reached. prospective randomized studies (Fig. 2). Data collection Population characteristic All information regarding participants and clinical out- Overall, 1013 patients/1041 knees were treated with HTO comes was recorded. Participant data included the and 5438 patients/5497 knees were treated with UKA. Pa- number of patients, age, gender, and number of knees tients’ age ranges were 42.7–71 years and 49.2–80 years, treated. The principle outcomes of interest included respectively. Only 11 studies [5, 8, 9, 12, 13, 15, 17–21] post-operative functional outcomes, range of motion, provided patients’ gender: 195 males and 277 females velocity, complications, and incidence of revision to underwent HTO, whereas 182 males and 374 females TKA. Data were documented independently by two underwent UKA. The follow-up period ranged from a authors after the qualifying studies were selected. minimum of 0.5 years to a maximum of 17 years. Eight studies [5, 12, 13, 15, 17, 19–21] reported the indications Quality assessment for inclusion in the study; these were strictly used for The reliability of results depends on the extent to which isolated medial knee OA with a varus deformity. The potential sources of bias have been avoided. To adopt the inclusion criteria for the other studies were varied or un- same method to evaluate all selected studies, two re- clear. Six papers [5, 12, 13, 15, 18, 20] reported the cohorts viewers independently applied the “assessing risk of bias” using the Ahlbäck OA score, and three papers [9, 17, 21] table to assess the risk of bias in each included study. The used the Kellgreen–Lawrence (K/L) score. All of the in- following biases were assessed: selection bias, performance cluded studies described the type of procedure, except one bias, attrition bias, detection bias, reporting bias, and [18] in the HTO group and three [8, 16, 18] in the UKA other bias. Disagreements were resolved through group. Details are provided in Tables 1 and 2. discussion between the reviewers. Meta-analysis Statistical analysis Because the measurement time points varied among stu- The heterogeneity of this study was determined by docu- dies, nearly all results reported here reflect the pooled data menting the methodological distinctions among several without period stratification. In addition, not all studies pre- studies by analyzing the data extraction tables. The I2 sented the essential data, introducing a potential bias to this test was used to evaluate statistical heterogeneity; if the study. Upon analyzing statistical heterogeneity, seven out- P value was less than 0.05 and the I2 value was less than comes showed substantial heterogeneity (I2 values >50%) 50%, a fixed-effects model was selected. However, in and were therefore interpreted with caution (Table 3). Santoso and Wu Journal of Orthopaedic Surgery and Research (2017) 12:50 Page 3 of 10 Fig. 1 PRISMA Chart Fig. 2 Risk of bias assessment shown in included studies There was limited evidence of a publication bias, with a broad symmetrical