==== Front J Orthop Surg Res J Orthop Surg Res Journal of Orthopaedic Surgery and Research 1749-799X BioMed Central London 2122 10.1186/s13018-020-02122-6 Systematic Review The comparison between total hip arthroplasty and hemiarthroplasty in patients with femoral neck fractures: a systematic review and meta-analysis based on 25 randomized controlled trials Tang Xiumei tangxiumei1997@outlook.com 1 Wang Duan 476825891@qq.com 2 Liu Ying liusaisaio@163.com 1 Chen Jiali cjl85614115@163.com 1 Zhou Zongke zhouzongke@scu.edu.cn 2 Li Peifang 18382076258@163.com 1 Ning Ning ningning6405@163.com 1 1 grid.13291.380000 0001 0807 1581West China School of Nursing, Sichuan University/Department of Orthopedics, West China Hospital, Sichuan University, Chengdu, 610041 People’s Republic of China 2 grid.412901.f0000 0004 1770 1022Department of Orthopedics, Orthopedic Research Institute, West China Hospital, Sichuan University, Chengdu, 610041 People’s Republic of China 10 12 2020 10 12 2020 2020 15 59617 8 2020 24 11 2020 © The Author(s) 2020Open AccessThis 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 http://creativecommons.org/licenses/by/4.0/. 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 in a credit line to the data.Background We performed an updated systematic review and meta-analysis which enrolled 25 prospective randomized controlled trials (RCTs) to compare the outcomes between total hip arthroplasty (THA) and hemiarthroplasty (HA) in patients with femoral neck fractures (FNFs). Methods We searched English databases which included PubMed, Embase (vis OvidSP), The Cochrane Library, and Web of Science, and Chinese databases Chinese National Knowledge Infrastructure (CNKI), VIP, Wang Fang, and China Biology Medicine Disc (CBM) in July 2020. The quality of each study was assessed according to the Cochrane Collaboration’s Risk of Bias. Risk ratios (RRs) and weighted mean differences (WMDs) with 95% confidence intervals (95% CIs) were pooled with random-effects models. Data regarding baseline characteristics, hospital and surgery outcomes, clinical outcomes, patients’ quality of life, common complications, prothesis-related complications, mortality, and costs were reported. Results A total of 25 RCTs involving 3223 patients (1568 THA and 1655 HA) were included. THA had longer hospital length (WMD = 0.721, P < 0.0001) and surgery time (WMD = 20.044, P < 0.0001), and more blood loss compared with HA (WMD = 69.109, P < 0.0001). THA showed better ratings in the Harris Hip Score during follow-up periods between 1 and 5 years while no differences within 6 months and after 9 years. THA was associated with higher quality-of-life EuroQol-5 Dimension (EQ-5D) scores after 2 years of surgery but no difference within 1 year. There was no difference in common complications. THA had significant higher rate of dislocation (WMD = 1.897, P = 0.002) and lower acetabular erosion (WMD = 0.030, P = 0.001). For mortality, there was no difference during all the follow-up periods except for slightly higher 2-year mortality after surgery. Conclusion This meta-analysis demonstrates that THA has better medium-term functional results and quality of life and lower acetabular erosion rate, while HA shows better in reducing hospital stay, surgery time, and blood loss and also has lower dislocation rate. Keywords Total hip arthroplastyHemiarthroplastyFemoral neck fracturesRandomized controlled trialsSupported by Sichuan Science and Technology ProgramNo.2019YJ0031Wang Duan issue-copyright-statement© The Author(s) 2020 ==== Body Background Femoral neck fractures (FNFs) will bring baneful influences to patients due to its high morbidity, disability rate, economic burden, and mortality, and the rate is rapidly growing because of the increasing number of the elderly [23]. Arthroplasty is commonly recommended for displaced femoral neck fractures (67% of all types FNFs) in the elderly (age > 65 years) and can be categorized as total hip arthroplasty (THA) and hemiarthroplasty (HA) [34]. Whether THA or HA is more applicable in FNF remains controversial [21]. Both pros and cons of the treatments were widely reported in previous studies and synthesized reviews but did not reach a common conclusion [6, 11, 13, 15, 17, 24, 26, 33, 49–52]. The ongoing discussion requires highly reliable answers. However, previous meta-analysis and reviews have several limitations. First, they did not fully mention the details of surgical approach, prosthetic choice, surgeon experience, and the type of both femoral and acetabular fixation, all of which we consider may cause chaos in conclusion. Second, serious inclusion criteria in some studies may lead to limited data to analyze. Third, subgroup analysis was limited, and long-term results were not considered. The latest meta-analysis included trials reported between 2006 and 2017 and may be outdated [33]. Randomized controlled trials (RCTs) with high quality have been published recently and not been included, and we carefully selected Chinese articles reported with enough follow-up duration and reported outcomes in our analysis [3, 8, 18, 25, 27, 31, 38, 44]. We conducted an updated meta-analysis only including RCTs to provide the most reliable evidence. Methods The review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (www.prisma-statement.org). Searches and selection criteria We searched English databases which included PubMed, Medline, Embase, The Cochrane Library, and Web of Science and Chinese databases CNKI, VIP, WAN FANG, and CBM (all inception to July 2020) without language or date restriction as well as retrieving articles identified in other reviews by manual search. And the search strategy is provided in Supplementary files. Inclusion criteria were RCTs comparing THA with HA for FNFs and at least reporting one of the predetermined outcomes. To make our conclusion generalizable, we set no restrictions for follow-up time, patients’ age, study size, or pre-surgery status. Outcome measures We included the following outcomes: Hospital and surgery outcomes: hospital stays, surgery duration, blood loss; Clinical outcomes: Harris Hip Scores (HHS) within 6 months and up to 13 years; Patients’ quality of life: EQ-5D scores within 6 months and at 1 to 2 years; Common complications: pulmonary embolism, deep vein thrombosis, pneumonia, urinary tract infection, pressure ulcer, wound disease, surgical-site infection, and cardiovascular disease. Prothesis-related complications: revision, fracture, dislocation, loosening or subsidence, heterotopic ossification, and acetabular erosion; Mortality: mortality in hospital, within 6 months, at 1 to 2 years and up to 13 years; Cost; Data extraction and study quality assessment Two reviewers (T-XM, WD) independently screened the titles and abstracts for eligibility. We develop a data extraction form and collected data from including articles after full-text reading and cross-checking procedures. Any discrepancies were evaluated by a third reviewer(C-JL). For study quality assessment, the Cochrane Collaboration’s Risk of Bias was used. For missing data like standard deviation, we calculated them with formulas according to the Cochrane handbook for systematic reviews of interventions or articles’ figure data. Statistical methods For statistical analysis, the review used forest plots to present the synthesized results. For continuous and binary variables, the weighted mean differences (WMD) and risk ratios (RR) were reported respectively with 95% confident interval (CI). Survivorship was analyzed through the Kaplan–Meier survivor curve. Heterogeneity was assessed by both Q2 and I2 tests, and P value < 0.1 or I2 > 50% indicates statistical heterogeneity. Galbraith tests and sensitivity analysis were used to identify the possible heterogeneity origins. If necessary, subgroups will be used to dismiss heterogeneity. The random effects model was conducted in any condition. We used sensitivity analysis by sequential omission of individual studies to validate the credibility of pooled data. For publication bias, the symmetry of funnel plots was visually evaluated, and Egger’s tests were also applied. For statistical analyses, the Review Manager (Version 5.0.2) and STATA (Version 13.0) software programs. All P values were two-sided. Results Search results Our review yielded 2325 reports and excluded 1356 after duplicates. Of these literatures, 48 were included after selecting the title and abstracts. After full text screening, 23 were excluded, and the details were described in the flow chart (Fig. 1). For clinical outcomes, we included 25 reports based on 19 trials and extracted non-repeating data at different follow-up stages ([1–4, 7, 8, 10, 12, 16, 18, 22, 25]; H. H [27].; W [29].; William [30, 31, 36–38, 40, 42–44, 46, 47]). Fig. 1 PRISMA flowchart of the selection process Methodological quality assessment In this study, selection, attrition, and reporting bias can be considered low risk. Detection bias was moderate risk as well as performance bias. Therefore, the methodological assessment of this work can be judged as very good quality. Two reviewers independently assessed the risk of bias of included studies according to the Cochrane Collaboration’s Risk of Bias, and the results are shown in Fig. 2. Fig. 2 Risk of bias of included studies according to the Cochrane Collaboration’s Risk of Bias Risk of publication bias Funnel plots of the outcome enrolled the most studies (dislocation) to detect publication bias. The symmetrical distribution and Egger’s test (P = 0.708) show low publication bias (Fig. 3). Fig. 3 Funnel plot based on dislocation rate Study characteristics We finally included 25 RCTs involving 3223 patients (THA 1568, HA 1655). Five of them ([1, 16]; W [29, 40].) were follow-up reports of previous trials. Table 1 summarizes the trials’ details. Table 1 Characteristics of the included studies Study Country Period Surgical approach Surgeon Patients number Age Woman ASA Median time to surgery, h Mobility Mental status THA HA Follow-up THA HA THA mean (SD) HA mean (SD) THA n (%) HA n (%) THA HA THA HA Baker et al. [2] and Avery et al. [1] England N/A Transgluteal lateral Similar training levels 40 41 74.2 (5.8) 75.8 (5) 32 (80%) 32 (78%) 2 (0.5) 2 (0.5) 42 46.8 Walk > 0.8 km; live independently MMSE9.83/9.98 Zimmer; femoral: cemented; head 28 mm cobalt chrome; acetabular: Polyethylene cemented Zimmer; cemented; unipolar 3 years for Baker et al. [2]; 9 years for Avery et al. [1] Bhandari et al. [3] Multiple centers 2009–2017 Not standardize 523 surgeons with expertise in THA/HA 718 723 79.1 (8.3) 78.6 (8.6) 510 (71%) 499 (69.1%) 22/280/305/50 20/275/326/51 54.9(79) 52.5(80.3) 1072 (walk dependently)/369 (with assistance) No dementia Mixed Mixed 2 years Blomfeldt et al. [4] and Hedbeck et al. [16] Sweden N/A Anterolateral 9 surgeons experienced in THA/HA 60 60 80.5 (4.9) 80.7 (4.8) 47 (78%) 54 (90%) N/A N/A N/A N/A 111 no aids or one aid (92.5%) SPMSQ > 9 Johnson; femoral: cemented; head 28 mm exter modular stem; acetabular: OGEE, DePuy Stryker cemented; bipolar 12 months for Blomfeldt et al. [4]; 48 months for Hedbeck et al. [16] Cadossi et al. [6] Italy 2008–2010 Straight lateral 2 experienced surgeons (SG, CF) 42 41 82.3 (6.3) 84.2 (6.3) 34 (81%) 28 (68%) 2/15/16/9 1/10/22/8 2.9 (1.75) 3.6 (1.5) Independently walk No senile dementia Unknown Femoral: uncemented; head: large metal; acetabular: 2.7-mm thick hydrophilic polycarbonate urethane (PCU) Mixed; bipolar 30.1 months Chammout et al. [8] Sweden 2009–2016 Direct lateral Consultant surgeon or registrar with assistance of consultant 56 62 85 (4) 86 (4) 45 (75%) 45 (75%) ASA1/2:30; ASA3,4:30 ASA1/2:20; ASA3,4:40 < 36 h < 36 h No aids or one aid: THA30 (50%)/HA29 (48%) SPMSQ:8-10 Schering-Plough Femoral: cemented; (vacuum-mixed low-viscosity cement with gentamicin);head 32-mm cobalt-chromium; acetabular: cemented highly cross-linked polyethylene Cemented; unipolar 2 years Dorr et al. [10] America 1980–1982 Posterior N/A 39 50 69 (9) 69 (12) 23 (60%) 35 (70%) N/A N/A N/A N/A Ambulate Mental status1/2: 70/19 Unknown Femoral: cemented; head: 28-mm; acetabular: unknown Mixed; bipolar 2 years Giannini et al. [12] Italy N/A N/A N/A 30 30 80.7 (6) 82.2 (6) N/A N/A N/A N/A N/A N/A N/A N/A Unknown Femoral: uncemented; head: large metal; acetabular: pliable, 3-mm-thick polycarbonate-urethane (PCU) Mixed; bipolar 1 year Iorio et al. [18] Italy 2015–2017 Direct lateral N/A 30 30 82 (4) 83 (3) 18 (60%) 17 (56.7%) 0/3/23/4 0/4/21/5 59 (13) 51 (15) Walk unaided MMSE < 18 Groupe Lépine Femoral: Uncemented; head: dual mobility cup Quattro; acetabular: N/A Uncemented; bipolar 2 years Keating et al. [22] England 1996–2000 Decided by surgeon Senior surgeon 69 111 75.2 (6) 75.4 (7) 52 (75%) 92 (83%) N/A N/A < 48 h < 48 h Independent MMSE > 6 Unknown Femoral: cemented; head: N/A; acetabular: N/A Cemented; bipolar 2 years Li et al. [25] China 2010–2012 Anterolateral N/A 40 40 76.5 (6.5) 75.8 (6.2) 17 (42.5%) 19 (47.5%) N/A N/A N/A N/A N/A Eliminate cognitive impairment Unknown Femoral: mixed; head: N/A; acetabular: N/A Mixed; N/A 2 years Liu et al. [27] China 2010–2012 Posterior N/A 54 54 74.19(6.4) 75.31 (6.2) 24 (44.44%) 26 (48.1%) N/A N/A N/A N/A N/A Excluded dementia patients N/A N/A 1 year Macaulay et al. [30] and Macaulay et al. [29] America N/A Posterolateral and direct lateral (Modified Hardinge) 14 surgeons, 5 reconstruction specialists 17 23 82 (7) 77 (9) 7 (41%) 14 (61%) N/A N/A N/A N/A Independently walk Excluded MMSE < 23 Mixed Mixed 1 year for Macaulay et al. [30]; 2 years for Macaulay et al. [29] Man et al. [31] China 2010–2012 Moore approach N/A 37 37 N/A N/A 28 (37.84%) 28 (37.84%) N/A N/A N/A N/A N/A No cognitive impairment Cemented; N/A Mixed; bipolar 3 years Mouzopoulos et al. [36] Greece 1999–2002 N/A N/A 37 34 73.07(4.9) 74.24 (3.77) 28 (75.68%) 24 (70.59%) 2.03 (1.97) 2.21 (1.9) 45.2 (7.3) 45.8 (2.4) Independently walk 37/34 SPMSQ 7.9 (2.6)/7.5 (3.1) N/A N/A 4 years Parker et al. [28] England 2012–2018 Anterolateral See in a. 52 53 77.1 (5.5) 77.1 (7.25) 40 (76.9%) 45 (84.9%) 2.2 2.0 N/A N/A Mean mobility grade 1.6/1.4 (9 grades) MMSE 8.7/8.9 Skinner et al. [37] and Ravikumar et al. [40, 41] England 1984–1986 Posterolateral See in b. 89 91 81.03 82.06 N/A N/A N/A N/A Within 24 h Within 24 h N/A Included patients with dementia Unknown Femoral: cemented (Howse II prosthesis); head 32 mm head; acetabular: semi-captive cup Bipolar; uncemented (Austin Moore) 2 years for Skinner et al. [37]; 13 years for Ravikumar et al. [40, 41] Sharma et al. [42] India 2010–2014 Modified Gibson Two senior arthroplasty surgeons 40 40 78 (3.5) 73 (1.25) 26 (65%) 29 (72.5%) N/A N/A 72 h 72 h N/A N/A N/A N/A 1 year Sonaje et al. [43] India 2011–2012 N/A N/A 21 21 66.4 (3.5) 65.3 (3) 13 (65%) 14 (70%) N/A N/A N/A N/A N/A No psychiatric and neurological disorder N/A N/A; bipolar 2 years Song et al. [44] China 2003–2012 N/A N/A 31 31 64.5 (5.8) 65.1 (5.9) 12 (38.71%) 10 (32.26%) N/A N/A N/A N/A N/A N/A N/A N/A; bipolar 1 year Van den et al. [47] and Tol et al. [46] Netherlands 1995–2002 Anterolateral; straight lateral; posterolateral Experienced surgeon or residents with assistant 115 137 82.1 (6.3) 80.3 (6.2) 90 (78%) 115 (84%) 11/48/44/10 19/77/33/5 1(2.25) 1(2.5) Walk without aids:149 N/A Sulzer AG/Protek AG Femoral: cemented (A Weber Rotations prosthesis, Müller Geradschaft prothesis); head 32 mm diameter modular head; acetabular: semi-captive cup Cemented; Bipolar; 5 years for Van den2010 and 12 years for Tol2017 aAll but eight operations were directly undertaken or supervised by the lead trialist. Two hemiarthroplasties and two THR’s were undertaken by orthopedic consultants and three hemiarthroplasties and one THR by trainee or staff grade surgeons bMostly by registers, occasionally by consultants or senior house officers cSPMSQ Short Portable Mental Status Questionnaire Outcome of interests The overall results are presented in Table 2. Table 2 The results of meta-analysis Variables N (study) N (THA) N (HA) Pooled data Heterogeneity WMD/RR(95%CI) P I2(%) Ph Hospital and Surgery  Hospital length 9 418 443 2.360 (0.215, 4.506) 0.031 96.0% < 0.0001  Hospital length (deleted Li et al. [25], Liu et al. [27]) 7 324 349 0.721 (0.362, 1.080) < 0.0001 0% 0.428  Surgery time 15 1292 1341 20.044 (14.257, 25.830) < 0.0001 95.7% < 0.0001  Blood loss 9 1063 1038 69.106 (39.083, 99.129) < 0.0001 96.4% < 0.0001  Blood loss (deleted developing countries’ studies) 4 881 856 76.027 (51.951, 100.104) < 0.0001 17.6% 0.303 Clinical outcomes  By follow-up   HHS(< 6 months) 5 208 208 1.641 (− 0.449, 3.731) 0.124 0% 0.784   HHS (at 1 year) 6 317 333 3.593 (1.278, 5.907) 0.002 12.5% 0.335   HHS (at 2 years) 5 174 168 3.691 (0.571, 6.812) 0.020 38.8% 0.162   HHS (3 to 5 years) 5 233 251 6.027 (0.434, 11.621) 0.035 90.1% < 0.0001   HHS (at 9 years) 2 57 71 5.848 (− 4.603, 16.299) 0.273 74.1% 0.050   Pain (HHS subscore) 3 148 148 0.065 (− 0.385, 0.515) 0.777 85.5% < 0.0001   Pain (HHS subscore, < 6 months) 2 97 97 − 0.042 (− 0.686, 0.602) 0.897 79.5% 0.027   Pain (HHS subscore, at 1 year) 3 128 128 0.405(− 0.575, 1.385) 0.418 92.7% 0.000   Pain (HHS subscore, at 2 years) 2 57 57 − 0.020 (− 0.902, 0.862) 0.964 78.6% 0.031   EQ-5D(<6 months) 3 183 214 0.031 (− 0.031, 0.093) 0.324 2.1% 0.360   EQ-5D(at 1 year) 3 181 177 0.033 (− 0.036, 0.102) 0.351 0.0% 0.951   EQ-5D(at 2 years) 3 173 165 0.107 (0.049, 0.164) < 0.0001 0.0% 0.525   Pain (binary) 3 827 783 0.244 (0.050, 1.183) 0.080 91.0% < 0.0001 Common complications  Pulmonary embolism 4 187 235 0.597 (0.158, 2.257) 0.447 0% 0.517  Deep vein thrombosis 8 397 439 1.004 (0.386, 2.614) 0.994 13.3% 0.326  Pneumonia 7 308 315 0.932 (0.431, 2.014) 0.858 0% 0.733  Pressure injury 4 183 185 1.233 (0.301, 5.056) 0.771 0% 0.516  Wound disease 10 1170 1227 0.857 (0.488, 1.505) 0.591 0% 0.933  Surgical site infection 5 967 974 0.963 (0.422, 2.200) 0.929 17.3% 0.305  Cardiovascular disease 6 286 335 1.474 (0.672, 3.233) 0.333 0% 0.669 Implant-related complications  Revision 13 1397 1480 0.736 (0.419, 1.292) 0.286 47.2% 0.030  Revision (Deleted Ravikumar et al. [40, 41]) 12 1308 1389 0.882 (0.513, 1.517) 0.651 30.3% 0.150  Fracture 7 1065 1094 1.064 (0.707, 1.600) 0.767 0% 0.853  Dislocation 16 1473 1562 1.897 (1.273, 2.827) 0.002 4% 0.407  Heterotopic Ossification 3 853 880 1.272 (0.844, 1.918) 0.251 0% 0.647  Loosening or Subsidence 2 833 860 0.640 (0.170, 2.409) 0.509 25.5% 0.247  Acetabular Erosion 2 215 238 0.030 (0.004, 0.219) 0.001 0% 0.769 Mortality  By follow-up   Mortality (in hospital) 8 414 456 1.484 (0.616, 3.579) 0.379 0% 0.434   Mortality (< 6 months) 2 69 76 0.679 (0.094, 4.892) 0.767 37.5% 0.206   Mortality (at 1 year) 7 372 394 1.011 (0.684, 1.493) 0.958 0% 0.705 Mortality (at 2 years) 8 1197 1294 1.224(1.055,1.421) 0.008 12.3% 0.334 Mortality(3 to 5 years) 2 249 270 1.138(0.869,1.490) 0.346 12.8% 0.284 Mortality(9 to 13 years) 3 435 473 1.021(0.881,1.183) 0.786 0% 0.489 Hospital and surgery outcomes Compared to HA, THA has longer surgery time (WMD = 20.044, P < 0.0001), more blood loss (WMD = 69.106, P < 0.0001), and longer hospital length (WMD = 2.360, P = 0.031). Fifteen studies reported surgery time (THA 1292, HA 1341) while nine studies reported hospital length (THA 418, HA 443) with high heterogeneity (I2 = 96%). We further did the Galbraith test and found the main source of the heterogeneity ([25]; H. H [27].). We excluded them, and the results are stable with no heterogeneity (I2 = 0%). For blood loss, nine studies were included (THA 1063, HA 1038), and the results are stable after removing developing countries’ studies (Fig. 4). Fig. 4 Forest plot of meta-analysis: Hospital and surgery outcomes Clinical outcomes The results evidenced THA has similar HHS score with HA within 6 months (WMD = 1.641, P = 0.124) or after 9 years (WMD = 5.848, P = 0.273) but higher scores at 1 year (WMD = 3.593, P = 0.002), 2 years (WMD = 3.691, P = 0.020), and 3 to 5 years (WMD = 6.027, P = 0.035) (Fig. 5). Three studies reported pain score based on HHS subscore, and other three studies reported pain as binary variables; the results of both show no difference between groups at any follow-up points. For patients’ quality of life, pooled data revealed no significant difference of EQ-5D scores up to 1 year after surgery. But the results favor THA 2 years later (WMD = 0.107, P < 0.0001) (Fig. 6). Fig. 5 Forest plot of meta-analysis: Harris Hip Score Fig. 6 Forest plot of meta-analysis: EQ–5D Patients’ quality of life The results showed that EQ-5D scores within 6 months (WMD = 0.031, P = 0.324) and at the first year after surgery (WMD = 0.033, P = 0.351) are similar between groups while favor THA 2 years later (WMD = 0.107, < 0.0001). Common complications The pooling data elicited no statistical difference across groups in terms of the events of pulmonary embolism, deep vein thrombosis, pneumonia, pressure injury, wound disease, surgical-site infection, and cardiovascular disease. Prothesis-related complications A total of 13 studies suggested that revision rate is similar in both groups with a moderate heterogeneity (I2 = 47.2%), the Galbraith test detected the main source, and the results are stable after deleting the study [40] (I2 = 30.3%). The study reported a result of 13 years follow-up thus generate the heterogeneity. Sixteen studies evidenced that THA has higher dislocations rate than HA with significant difference (WMD = 1.897, P = 0.002). Compared with THA, HA has a higher rate of acetabular erosion (WMD = 0.030, 95% CI 0.004 to 0.219, P = 0.001) (Fig. 7). As for fracture, loosening or subsidence, and heterotopic ossification, the results detected no statistical difference between groups. Fig. 7 Forest plot of meta-analysis: Prosthesis-related complications Mortality The Kaplan–Meier curve was applied, and we detected the similarity of survivorship (HR 1.029; 95% CI 0.905 to 1.169; P = 0.665; Fig. 8). Subgroup analysis of 2 years follow-up revealed reduced mortality in HA group (WMD = 1.224, P = 0.008) Fig. 8 Survival curve Discussion Hospital and surgery outcomes For surgery time, almost all previous synthesized outcomes are in consistence with our results [24, 28, 33, 48, 49]. And we consider the main reasons are that HA requires less operative installation steps including cup preparation and implantation. For hospital length, we found that THA has longer in-hospital duration in our study. The common reasons for delayed discharges are usually post-surgery complications, since we did not find out the difference in common complications, and we consider that the early ambulation ability for patients who undergone HA may cause the difference. We also found reduced blood loss in HA group and less surgical procedures; tissue damage may clarify the results. All three indicators are in favor of HA group, and the results are hardly to change even with more evidence. However, the results may lack clinical values when it comes to decision-making. Clinical outcomes Many studies have proved better outcomes in THA group in terms of HHS but did not provide long-term results or subgroup analysis due to limited trials ([24]; Y [28, 33, 49].). We made subgroups based on follow-up periods and initially found that THA group has higher total HHS in medium term (1–5 years) but no difference in short (< 6 months) or long terms (> 9 years). For pain scores, we detect no difference between two groups, and the PCU-THA used in one trial is the main source of heterogeneity [6]. Liu (Y [28].) and Wang [20] found that patients in THA group experienced significantly less pain, but they only include limited trials in the pooled results. Patients’ quality of life For EQ-5D scores, our conclusion agreed with other studies that THA has better overall patients’ quality of life ([24]; Y [28, 48, 49].). We did the subgroup analysis and found that the difference became obvious 2 years after the surgery. Common complications Our result found no difference in terms of common complications, and we believed further studies can hardly change it. Our results are against Liu et al.’s study (Y [28].). In his study, he limited patients’ age to over 75 years old, and we believe the complications may largely be attributed to the patients’ own condition rather than implants type. Prothesis-related complications The results show that revision rate is similar with moderate heterogeneity (I2 = 47%). After sensitivity analysis, Ravikumar and Marsh’s [41] study was considered as the source because they reported 13-year follow-up results (24% in HA; 6.75% in THA). In meta-analysis that only include RCTs, Metcalfe et al. [32], Liu et al. (Y [28].), and Migliorini et al. [33] are in favor of our results but Migliorini et al. found a higher revision rate in THA within 5 years while in HA after 5 years. Lewis et al. [24] found that THA was superior to HA, but the non-RCTs in his study may influence the evidence grades. However, data from registries are in contrast to the results from randomized trials because RCTs always have certain selections of enrolled patients. According to national registry studies, dislocation, infection, and periprosthetic fracture are the main reasons for revision [35, 45]. Anterolateral approach, cemented stem, bipolar head, and 36-mm cups are useful methods to reduce revisions and should be considered by the surgeons for the best outcomes for patients [14, 32, 35, 45]. Dislocations are always a concern by clinical doctors because they are the main reason for revision. We found that THA has a higher rate of dislocation compared with HA. The types of head (bipolar vs. unipolar), cups (dual-mobility vs. single cup), age of patients, pre-injury ambulation status, and surgical approaches may cause influence on the dislocation rate. Our conclusion is in line with other reviews and registry reports ([19, 24]; Y [28, 33].; ). Acetabular erosion is a theoretical indication to perform a revision in a painful HA. The pooled data shows higher acetabular erosion rate in HA group. And we found no dissent from other authors. Osteoarthritis also represents an important pillar for the decision on therapy. Usually, surgeons are conservative about THA due to the elevated risk of dislocation, with the associated risk of subsequent revisions and the death risk in the end. However, our results found that the revision rate is similar between two groups. The possible reason is that THA has higher dislocations rates while HA has higher acetabular erosion rates and thus equals the revision rate between the two groups. The long-term results favor the THA, and surgeons could choose propriate implants and approaches to reduce dislocation rates. Mortality We found that the mortality rate was similar in groups, and comparable results were found by other meta-analysis [24, 33, 48, 49]. However, we found that THA has a slightly higher mortality rate 2 years after surgery, and it proves the detective ability of our study. We hypothesize that the early revision caused by dislocations will lead to more deaths in THA group while will be offset by acetabular erosion later. But the result should be interpreted carefully with more studies. Cost Three studies mentioned the cost of both techniques. Burgers et al. [5] found that main cost were rehabilitation fares and nursing home care payments in the first year after surgery. Keating et al. [22] found that the cost between groups was not significant, but highlight the high costs of the readmissions in patients who underwent HA. Ravi et al. [39] found that THA reduced health care costs about the index admission 1 year after surgery, relative to HA. Dangelmajer et al. [9] found that patient’s age and medical care payer status were all associated with odds of receiving THA, and patients with private insurance had higher odds of receiving THA. Reducing costs after hip fracture surgery should focus on improving the duration and efficiency of the rehabilitation phase. The economic evidence showed that THA should be more considered because it can cut the cost of readmission and rehabilitation. Limitations There are some limitations also needed to be noticed. First, lack of information (implant types, operative approach, etc.), uncontrollability of confounders (medical resources, surgeon experience, etc.), and other factors might affect the credibility of the pooled data despite that we selected the most reliable types of trials. Secondly, we did not set strict inclusion criteria since they have already been considered in the process of RCTs, and the low heterogeneity of these results also proves it. Thirdly, despite that our results suggested the difference between short-term and long-term results in functional outcomes and patients’ quality of life, the long-term reports are still limited. Therefore, the multicentered and large population-based designs of future research should be considered, and more long-term follow-up surveys should be focused and reported. Conclusion Based on the results, we thought HA could be recommended for patients who have cognitive impairment, comorbidities, reduced performance status, and low function demands. And THA should be recommended for patients who are active, healthy, with long life expectancy and young biological age, and have higher demands for functions and quality of life. Supplementary Information Additional file 1: Supplementary file 1. Search Strategy Abbreviations RCTsRandomized controlled trials THATotal hip arthroplasty HAHemiarthroplasty FNFsFemoral neck fractures CNKIChinese National Knowledge Infrastructure CBMChina Biology Medicine Disc RRsRisk ratios WMDsWeighted mean differences CIsConfidence intervals PRISMAPreferred Reporting Items for Systematic Reviews and Meta-Analyses EQ-5DEuroQol Five Dimensions Questionnaire HHSHarris Hip Scores Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Supplementary Information The online version contains supplementary material available at 10.1186/s13018-020-02122-6. Acknowledgements Not applicable Authors’ contributions TXM conceived the methods of the study; performed the database search, the article selection, and data extraction processes; performed the statistical analysis; and drafted the manuscript. WD conceived the methods of the study; performed the database search, the article selection, and data extraction processes; and drafted the manuscript. CJL conceived the methods of the study, helped with the data extraction process, and drafted the manuscript. LY, LPF, NN, and ZZZ helped to draft the manuscript. All authors read and approved the manuscript. Funding Supported by the Sichuan Science and Technology Program (No.2019YJ0031) Availability of data and materials The datasets used during the current study are available from the corresponding author on reasonable request. Ethics approval and consent to participate This meta-analysis and all the included studies meet all the ethical standards described in the declaration of Helsinki. No ethical committee approval was required for this study. Consent for publication Not applicable Competing interests The authors declared no competing interests. ==== Refs References 1. 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