The Effect of Enhanced Recovery after Surgery Protocol in Orthopedic Hip Surgery: A Systematic Review and Meta-Analysis

Abstract

Background

The Enhanced Recovery After Surgery (ERAS) protocol has garnered global attention for optimizing perioperative care. It holds significant potential for orthopedic hip surgery, especially in elderly patients requiring rehabilitation. However, large-scale studies or meta-analyses specific to this field remain limited.

Methods

A systematic search was performed using Medline (PubMed), Embase, and Cochrane Library databases for studies assessing the effects of the ERAS protocol in hip surgery up to August 13, 2024. A double-arm meta-analysis was designed to compare perioperative outcomes, including postoperative pain scores, transfusion rates, medical and surgical complications, and length of hospital stay, between ERAS and control groups.

Results

Twenty-one studies were systematically reviewed, and 13 were included in the pooled analysis, comprising 1,004 patients in the ERAS group and 1,159 in the control group. Meta-analysis results demonstrated that the ERAS protocol significantly improved postoperative pain management, reduced blood transfusion requirements, decreased medical complications, and shortened hospital stays compared to standard protocols.

Conclusions

This meta-analysis supports the hypothesis that the ERAS protocol enhances perioperative outcomes in orthopedic hip surgery.

The concept of the Enhanced Recovery After Surgery (ERAS) protocol was first introduced in Denmark in 1997,¹⁾ with the aim of controlling postoperative pathophysiology and rehabilitation through a multimodal approach. It is also referred to by other terms such as “fast track” or “early recovery” protocols.²⁾ It has expanded globally and is now recognized across all surgical fields. ERAS is not simply a single technique but rather a pathway that integrates multiple modalities to support smooth pain management and rapid recovery for patients throughout the entire treatment journey, from preoperative to postoperative care. Key components typically include epidural analgesia, early mobility, and early oral nutrition.²⁾ In orthopedic surgery, it also includes measures such as the use of tranexamic acid to reduce perioperative blood loss, maintenance of body temperature during surgery, and decisions regarding the use of drainage at the operation site.³⁾

While the overall framework of the ERAS protocol remains the same, the specifics can vary between different centers. In the orthopedic field, there has been active research, particularly in joint and spine surgeries,⁴⁾ though consensus is still lacking. Hip surgery involves a larger proportion of patients with comorbidities, which could make the application of the ERAS protocol more impactful. However, there is still a lack of large-scale studies or meta-analyses examining the effectiveness of ERAS protocols in orthopedic hip surgery. Studies in the orthopedic field have only become more prevalent after 2020, and there is still a scarcity of up-to-date meta-analyses.

This study aimed to focus on orthopedic hip surgery and analyze the results of the ERAS protocol. The hypothesis was that the group undergoing the ERAS protocol would show superior outcomes compared to the control group in all aspects, including postoperative pain scores, blood transfusion rates, medical and surgical complications, and length of hospital stay (LOS).

METHODS

We conducted this study in accordance with the Revised Assessment of Multiple Systematic Reviews and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.⁵,⁶⁾ Although this research involved human participants, ethical approval and informed consent were not necessary, as all data were derived from previously published studies and were analyzed anonymously, posing no risk to participants.

Literature Search

A computerized search of Medline (PubMed), Embase, and Cochrane Library was performed for studies that investigated the effect of the ERAS protocol in orthopedic hip surgery. Using an a priori search strategy, we identified articles published up to August 13, 2024. Search terms included synonyms and terms related to the ERAS protocol and hip surgeries. The full search strategies and results for all databases are presented in Supplementary Material 1. We imposed no language restrictions in our literature search and placed no restrictions on the publication year. After the initial electronic search, we manually searched for relevant articles and their bibliographies.

Study Selection

With extensive experience in meta-analysis, 1 university hospital orthopedic professor (CHK) and 1 orthopedic specialist (DHL) independently selected the articles for full-text review from the titles and abstracts of the studies. If the abstract provided insufficient data to decide, the entire article was reviewed.

This meta-analysis was designed as a pairwise meta-analysis. Studies were included based on the “Patient, Intervention, Comparator, Outcomes, and Study design (PICOS) criteria:⁷⁾ (1) “Patient” was set as the patients who underwent orthopedic hip surgery, (2) “Intervention” was set as the ERAS protocol, (3) the control group that did not receive the ERAS protocol was set as the “Comparator,” and (4) “Outcomes” were investigated for all postoperative variables. The process of identifying and selecting studies is outlined in Fig. 1.

Fig. 1. Flow diagram illustrating the identification and selection process for studies included in the meta-analysis.

We excluded the studies if they (1) were non-original articles (n = 70), (2) were irrelevant to the research question (n = 115), (3) were duplicates from the same investigation group (n = 48), (4) were conference abstracts (n = 147), or (5) lacked a comparative group (n = 30). When study populations overlapped, we selected the publication with the largest population for the meta-analysis.

At each stage of article selection, the κ-value was calculated to determine inter-reviewer agreement regarding study selection. Agreement between reviewers was correlated a priori with κ-values as follows: κ = 1 corresponded to “perfect” agreement, 1.0 > κ ≥ 0.8 to “almost perfect” agreement, 0.8 > κ ≥ 0.6 to “substantial” agreement, 0.6 > κ ≥ 0.4 to “moderate” agreement, 0.4 > κ ≥ 0.2 to “fair” agreement, and κ < 0.2 to “slight” agreement. Disagreements at each stage were resolved by discussion between the 2 investigators to reach a consensus or by a discussion with a third investigator (JWK), who was a board-certified orthopedic faculty member, when a consensus could not be reached.

Data Extraction

For qualitative data synthesis, the following information and variables were extracted using a standardized form: (1) study design, (2) the country in which the investigation took place, (3) the type of surgeries, (4) number of patients in each ERAS group and control group, (5) follow-up length for study groups, (6) Methodological Index for Non-Randomized Studies (MINORS) score, (7) mean patient age, (8) female sex, and (9) the detailed content of each ERAS protocol.

For the pairwise meta-analysis, we only conducted a meta-analysis of variables for which data from 3 or more studies could be extracted. Finally, we compared (1) postoperative visual analog scale (VAS) scores, (2) red blood cell transfusion rates, (3) medical complications, (4) surgical complications, and (5) LOS between the ERAS protocol group and the control group. For the subgroup analysis, we aimed to analyze each variable according to the type of surgery. In each subgroup analysis, we proceeded only if data could be extracted from at least 3 studies.

Risk-of-Bias Assessment

For the 3 included randomized controlled trials (RCTs), we conducted a risk-of-bias assessment using the Revised Cochrane risk-of-bias tool for randomized trials (RoB 2).⁸⁾ Each RCT was evaluated across 5 domains: the randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result. Judgments were coded as “low risk,” “some concerns,” or “high risk.” A numeric summary of these domain-level assessments was also generated by assigning 1 point for “low risk,” 2 points for “some concerns,” and 3 points for “high risk.” We also assessed the methodological quality of the included studies using the Methodological Index for Non-randomized Studies (MINORS),⁹⁾ a validated tool for assessing the quality of nonrandomized studies. MINORS checklists comprised methodological items for nonrandomized studies (16 points) and additional criteria in the case of comparative studies (8 points). The maximum MINORS checklist score for comparative studies was 24 points. Two independent reviewers (JWK and CHK) performed quality assessments. Disagreements were resolved through discussion.

Statistical Analysis

For all comparisons, the continuous data were analyzed using standard mean differences with 95% CIs, and for dichotomous data, we calculated odds ratios (ORs) and 95% CIs. We assessed heterogeneity using the I² statistic, considering 25%, 50%, and 75% as low, moderate, and high heterogeneity, respectively. We used forest plots to present the outcomes, pooled estimates of effects, and the overall summary effect of each study.

We set the statistical significance value at p < 0.05. We pooled all data using a random-effects model, as recommended in the medical field, to avoid overestimating the study results.¹⁰⁾ The fixed-effects model begins with the assumption that the true effect size is similar in all included studies; thus, we believed that the random-effects model was generally a more plausible match for the current study.

We performed a test for publication bias for the main outcomes but did not perform it for the subgroup analyses because evaluations for publication bias are recommended only when at least 10 studies are included in a meta-analysis.¹¹⁾ The statistical analyses were performed using Review Manager (RevMan) software (version 5.3; Copenhagen, The Nordic Cochrane Center, The Cochrane Collaboration, 2014) and the “Metafor” package in R (version 3.4.3; R Foundation for Statistical Computing).

RESULTS

Article Identification

Details of the study identification and selection processes are summarized in Fig. 1. The initial electronic literature search yielded 725 articles. After removing 286 duplicates, 439 articles remained. Of these, 410 articles were excluded after screening their titles/abstracts, and 5 studies could not be retrieved. Additionally, 3 articles were excluded after full-text review. Therefore, 21 studies¹²,¹³,¹⁴,¹⁵,¹⁶,¹⁷,¹⁸,¹⁹,²⁰,²¹,²²,²³,²⁴,²⁵,²⁶,²⁷,²⁸,²⁹,³⁰,³¹,³²⁾ were included in the review process. Of these, 13 reports¹²,¹³,¹⁵,¹⁷,¹⁸,¹⁹,²²,²³,²⁸,²⁹,³⁰,³¹,³²⁾ were included in the meta-analysis. The κ-values between the 2 reviewers were substantial at the title review stage (κ = 0.684), almost perfect at the abstract review stage (κ = 0.911), and perfect agreement at the full-text review stage (κ = 1.000).

Study Characteristics and Qualitative Synthesis

The studies included 3 prospective cohort studies,¹¹,²⁷,³⁰⁾ 3 RCTs,¹²,¹⁴,¹⁸⁾ and 7 retrospective cohort studies.¹⁶,¹⁷,²¹,²²,²⁸,²⁹,³¹⁾ Most of the studies were conducted in Asia (7 studies),¹⁷,¹⁸,²¹,²⁸,²⁹,³⁰,³¹⁾ with others originating from Europe (4 studies),¹²,¹⁴,¹⁶,²²⁾ South America (1 study),¹¹⁾ and Australia (1 study).²⁷⁾ A total of 1,059 participants were included, with individual study sample sizes ranging from 45 to 180. The mean patient age was primarily in the late 50s to early 70s. Most study populations were female-dominant. The primary surgeries analyzed were total hip arthroplasty (THA),¹¹,¹²,¹⁴,¹⁶,¹⁷,¹⁸,²¹,²²,²⁸,²⁹,³⁰⁾ while 2 studies focused on proximal femoral nail antirotation (PFNA) intramedullary fixation.¹⁸,³¹⁾ Follow-up durations ranged from 1 to 12 months.

ERAS protocols incorporated a range of strategies designed to minimize surgical stress, enhance pain control, and facilitate early recovery. Spinal anesthesia was widely utilized as a key component in several studies,¹¹,¹⁴,²⁷⁾ employing specific combinations such as bupivacaine with clonidine¹¹⁾ or prilocaine with sufentanil¹⁴⁾ to ensure effective pain relief while reducing systemic side effects. In some protocols, opioid-free anesthesia was implemented to minimize risks associated with opioids, using alternatives such as celecoxib preoperatively and tramadol postoperatively.¹⁸⁾ Pain management was further supported by multimodal strategies, including tranexamic acid to reduce bleeding and inflammation,¹¹,¹⁴,²⁷⁾ peri-articular injections of ropivacaine and methylprednisolone,¹¹⁾ and non-steroidal anti-inflammatory drug (NSAIDs) or intravenous (IV) dexamethasone for anti-inflammatory effects.¹⁴,¹⁷⁾ Additional details are provided in Supplementary Material 2.

Surgical techniques emphasized minimally invasive approaches to reduce tissue trauma and promote faster recovery. For example, a minimally invasive posterior incision was used in some cases,¹²⁾ while others incorporated thrombosis prophylaxis using dalteparin and rivaroxaban to mitigate postoperative complications.¹⁶⁾ Early mobilization was a cornerstone of ERAS protocols, with patients encouraged to begin rehabilitation within hours after surgery. Studies reported that mobilization typically commenced within 3–5 hours postoperatively,¹¹,¹²,¹⁴,¹⁶,¹⁸⁾ with physiotherapy sessions initiated on the same day or the following morning to accelerate functional recovery.²⁷,³⁰⁾

Preoperative preparation and postoperative care also played significant roles in these protocols. Preoperative carbohydrate loading was employed in some cases to improve metabolic readiness,²²⁾ while psychological counseling helped reduce anxiety and prepare patients for surgery.³⁰⁾ Postoperatively, multidisciplinary care plans tailored to individual needs, along with regular monitoring of key clinical markers such as hemoglobin and D-dimer levels, contributed to improved patient outcomes.¹⁷,²⁹⁾ Details on study designs, ERAS protocols, and demographic distributions are provided in Tables 1 and 2.

Table 1. Study Design and MINORS Scores of Included Studies.

Study	Design	Country	Type of surgery studied	FU length (mo)	MINORS score
de Carvalho Almeida et al. (2021)12)	PCS	Brazil	THA (primary)	12	19
Elmoghazy et al. (2022)13)	RCT	Germany	THA (primary)	3	19
Gotz et al. (2024)15)	RCT	Germany	THA (primary)	3	23
Heinrich et al. (2024)17)	RCS	Swiss	THA (primary)	3	15
Huang et al. (2023)18)	RCS	China	THA (primary)	6	16
Kang et al. (2019)19)	RCT	China	PFNA IM fixation (primary)	6	19
Long et al. (2024)22)	RCS	China	THA (primary)	12	16
Macfie et al. (2012)23)	RCS	UK	Hemiarthroplasty (primary)	3	17
Tan et al. (2018)28)	PCS	Australia	THA (primary)	3	22
Tian et al. (2020)29)	RCS	China	THA (primary)	1	19
Wang et al. (2023)30)	RCS	China	THA (primary)	3	19
Zhong et al. (2021)31)	PCS	China	THA (primary)	12	19
Zhu et al. (2021)32)	RCS	China	PFNA IM fixation (primary)	12	16

MINORS: Methodological Index for Non-Randomized Studies, FU: follow-up, PCS: prospective cohort study, THA: total hip arthroplasty, RCT: randomized controlled trials, RCS: retrospective cohort study, PFNA IM: proximal femoral nail antirotation intramedullary.

Table 2. Demographics and ERAS Details of Each Study.

Study	Sample size (n, ERAS/control)	Mean patient age (yr, ERAS/control)	Female sex (ERAS/control)	Key ERAS protocol
de Carvalho Almeida et al. (2021)12)	47/51	56.4 ± 7.42/58.2 ± 8.17	22 (47)/26 (51)	Spinal anesthesia, tranexamic acid, early rehabilitation
Elmoghazy et al. (2022)13)	30/30	65.2 ± 6.38/72.1 ± 8.25	10 (33.3)/20 (66.6)	GA, minimal incision, mobilization in 3–5 hr
Gotz et al. (2024)15)	98/96	64.31 ± 9.87/65.55 ± 8.45	NR/NR	Spinal anesthesia, early physio, pain management
Heinrich et al. (2024)17)	100/150	70.3 ± 6.21/68.2 ± 5.37	58 (58.0)/82 (54.7)	Direct anterior approach, rapid mobilization
Huang et al. (2023)18)	65/194	69.0 ± 10.3/71.2 ± 8.8	41 (62.5)/111 (42.6)	Early exercises, multidisciplinary care
Kang et al. (2019)19)	50/50	77.81 ± 8.14/78.32 ± 8.24	35 (70)/34 (68)	Preoperative education, opioid-free anesthesia
Long et al. (2024)22)	48/38	68.3 ± 7.5/69.2 ± 7.3	30 (62.5)/22 (57.9)	Multimodal pain relief, early mobility
Macfie et al. (2012)23)	117/115	81 ± 9.1/80 ± 9.3	65 (55.6)/63 (54.8)	Fascia iliacus block, preoperative carb loading
Tan et al. (2018)28)	115/115	65 ± 7.8/64 ± 8.1	59 (51.3)/58 (50.4)	Early antiemetics, tranexamic acid
Tian et al. (2020)29)	47/45	75 ± 6.0/74 ± 6.2	32 (68.1)/31 (68.9)	Hip function assessment, reduced LOS
Wang et al. (2023)30)	45/45	67 ± 6.5/66 ± 6.8	31 (68.9)/34 (75.6)	-
Zhong et al. (2021)31)	180/168	65 ± 11.2/64 ± 12.1	101 (56.1)/92 (54.8)	-
Zhu et al. (2021)32)	62/62	76 ± 8.2/75 ± 8.5	39 (62.9)/40 (64.5)	Functional recovery focus, reduced LOS

Values are presented as mean ± standard deviation or number (%).

ERAS: Enhanced Recovery After Surgery, GA: general anesthesia, NR: not reported, LOS: length of stay.

Risk of Bias Assessment

Among the 3 RCTs,¹³,¹⁵,¹⁹⁾ no domain was judged at “high risk” of bias. The average numeric rating (on a 1-to-3 scale) across all domains was 1.27, indicating that most judgments were either “low risk” or “some concerns.” Overall, 1 RCT was rated as “low risk” (with a minor concern in 1 domain), while the other 2 were rated as “some concerns.” There were no indications that any specific methodological limitations critically threatened the validity of the results from the RCTs.

The mean MINORS score for methodological quality assessment was 18.4 of 24 (range, 16–23). Regarding the 8 main evaluation parameters, all included studies clearly addressed the aim of this analysis (item 1: a clearly stated aim), and 7 studies¹²,¹⁷,¹⁹,²⁰,²³,²⁷,²⁸⁾ included consecutive patients appropriately (item 2: inclusion of consecutive patients). Nine studies¹⁴,¹⁷,¹⁸,²¹,²²,²³,²⁶,²⁷,³²⁾ received a point deduction for their retrospective design (item 3: prospective collection of data), and all included studies appropriately set their aim of study (item 4: endpoints appropriate to the aim of the study). Five studies¹²,¹⁵,¹⁶,²⁴,²⁵⁾ performed the blind evaluation of objective endpoints (item 5: unbiased assessment of the study endpoint), and 2 studies²²,²⁷⁾ were deducted points due to follow-up period (item 6: follow-up period appropriate to the aim of study). Three studies¹⁵,¹⁶,²⁸⁾ had less than 5% loss to follow-up of initially included patients, and 4 studies¹⁵,¹⁶,²⁷,²⁸⁾ performed prospective calculation of the sample size (item 8: prospective calculation of the study size). Additional details and criteria for the domains are provided in Table 1.

Meta-Analysis

Patient-reported outcome: VAS

Five studies¹⁸,¹⁹,²⁹,³¹,³²⁾ reported VAS scores. In the pooled analysis, both VAS scores on postoperative day 3 and postoperative day 5 were significantly higher in the control group compared to the ERAS protocol group. On postoperative day 3, the mean difference was 1.46 points higher in the control group (95% CI, –1.61 to –1.31; p < 0.01; I² = 97%), and on postoperative day 5, it was 0.93 points higher (95% CI, –1.18 to –0.68; p < 0.01; I² = 62%). This indicates that the group following the ERAS protocol experienced less pain on both postoperative day 3 and day 5. Additional details, including the forest plot, are shown in Fig. 2.

Fig. 2. Forest plot comparing postoperative visual analog scale scores between the Enhanced Recovery After Surgery (ERAS) protocol group and the control group on postoperative day 3 (A) and postoperative day 5 (B). SD: standard deviation, IV: inverse variance method.

For the subgroup analysis, a separate pooled analysis was conducted for patients undergoing THA, and the results are presented in Supplementary Material 1. A total of 3 studies were pooled, showing that on postoperative day 3, the VAS score in the control group was 1.54 points higher than in the ERAS protocol group (95% CI, –1.71 to –1.38; p < 0.01; I² = 98%). However, due to insufficient data, pooling for postoperative day 5 could not be performed.

Blood transfusion rate

Three studies¹²,¹³,¹⁷⁾ reported the blood transfusion rate. The pooled analysis revealed that the group following the ERAS protocol had an average transfusion rate of 2.3% (4/177 patients), while the control group had a transfusion rate of 21.2% (49/231 patients). The OR difference between the 2 groups was 0.07 (95% CI, 0.03 to 0.20; p < 0.01; I² = 74%), indicating a significantly higher transfusion rate in the control group. Additional details, including the forest plot, are shown in Fig. 3.

Fig. 3. Forest plot comparing allogenic transfusion rates between the Enhanced Recovery After Surgery (ERAS) protocol group and the control group. M-H: Mantel-Haenszel method.

Medical complications

Six studies¹³,¹⁵,¹⁹,²²,²³,³²⁾ reported medical complications. In the pooled analysis, 11.6% (47 out of 405 patients) in the ERAS protocol group experienced medical complications, compared to 17.6% (69 out of 391 patients) in the control group. The overall OR was 0.57, indicating significantly fewer medical complications in the ERAS protocol group (95% CI, 0.37 to 0.88; p = 0.01; I² = 67%) (Fig. 4).

Fig. 4. Forest plot comparing overall medical complication rates between the Enhanced Recovery After Surgery (ERAS) protocol group and the control group. M-H: Mantel-Haenszel method.

Subgroup analysis revealed that pneumonia incidence was significantly lower in the ERAS group, with an OR of 0.42 (95% CI, 0.20 to 0.90; p = 0.03; I² = 0%). However, there were no significant differences for cardiovascular events, deep vein thrombosis, or urinary tract infections. Details are provided in Table 3.

Table 3. Odd Ratios of Medical Complications Following Subgroup Analysis Comparing ERAS Protocol Group and Control Group.

Subgroup and outcome		No. of studies	Odds ratio (95% CI)	I2 (%)	p-value
Medical complication
	Pneumonia	4	0.42 (0.20–0.90)	0	0.03
	Cardiovascular event	4	0.65 (0.23–1.86)	0	0.42
	Deep vein thrombosis	4	0.22 (0.02–2.01)	0	0.18
	Urinary tract infection	3	0.39 (0.10–1.56)	0	0.19
Surgical complication
	Surgical site infection	5	0.51 (0.08–3.20)	NA	0.47
	Revision rate	4	1.80 (0.38–8.58)	37	0.46

ERAS: Enhanced Recovery After Surgery, NA: not applicable.

Surgical complications

Six studies¹³,¹⁵,¹⁹,²²,²³,³²⁾ reported surgical complications. The pooled analysis revealed that the frequency of surgical complications was 1.7% (7 out of 405 patients) in the ERAS protocol group and 1.5% (6 out of 391 patients) in the control group, with no statistically significant difference (OR, 1.06; 95% CI, 0.35 to 3.21; p = 0.92; I² = 17%) (Fig. 5). Subgroup analysis of surgical site infections and revision surgeries showed no significant differences between the groups. Details are provided in Table 3.

Fig. 5. Forest plot comparing overall surgical complication rates between the Enhanced Recovery After Surgery (ERAS) protocol group and the control group. M-H: Mantel-Haenszel method.

Length of hospital stay

Eight studies¹²,¹³,¹⁸,¹⁹,²⁸,³⁰,³¹,³²⁾ evaluated the LOS. In the pooled analysis, the ERAS protocol group had an average LOS that was 3.61 days shorter than the control group, which was statistically significant (95% CI, –4.79 to –2.43; p < 0.01; I² = 97%). Additional details, including the forest plot, are shown in Fig. 6. For the subgroup analysis, a pooled analysis was conducted for patients undergoing THA. Similar to the overall group, the ERAS protocol group had a shorter average LOS than the control group, with a reduction of 3.70 days (95% CI, –3.96 to –3.44; p < 0.01; I² = 86%). Details are provided in Supplementary Material 2.

Fig. 6. Forest plot comparing the length of hospital stay between the Enhanced Recovery After Surgery (ERAS) protocol group and the control group. SD: standard deviation, IV: inverse variance method.

DISCUSSION

The principal finding of this meta-analysis is that the application of the ERAS protocol in orthopedic hip surgery has favorable effects on postoperative pain management, reduced blood transfusion requirements, fewer medical complications, and shortened overall hospital stays compared to standard protocols. This finding aligns with previous studies, and the results of the updated individual studies included in this meta-analysis also support this conclusion.

A prior meta-analysis published in 2021³³⁾ analyzed the effectiveness of the ERAS protocol in hip fracture surgery. That study concluded that the ERAS protocol could reduce time to surgery, LOS, and overall complication rates but did not reduce readmission rates or mortality. However, some limitations of this study include (1) it was limited to hip fractures only, (2) the data analysis was restricted to studies published until July 2020, and (3) only 7 articles were ultimately included, resulting in somewhat limited data. In contrast, our study not only analyzed hip fractures but also covered a broader range of orthopedic hip surgeries and used updated data. From 2021 to 2024, there was a significant increase in studies on the ERAS protocol in PubMed compared to before 2020. Consequently, our study analyzed a considerably larger number of articles than the previous research.

One of the most important elements of the ERAS protocol is perioperative pain management.³⁴⁾ To achieve this, multimodal analgesia is usually prescribed, often combined with nerve blocks or peri-articular infiltration analgesia particularly in the orthopedic field.³⁾ This approach is not only effective in pain control but also reduces the amount of opioids traditionally used after surgery, which in turn helps decrease complications, as supported by numerous studies.³,³⁵⁾ Therefore, the finding in this meta-analysis that VAS scores on postoperative days 3 and 5 were lower in the ERAS protocol group compared to the control group is consistent with previous research results.

As part of the ERAS pathway’s efforts to reduce allogenic blood transfusions after surgery, a commonly considered option is the use of tranexamic acid in orthopedic hip surgery.³⁶⁾ This can be administered intravenously or as an intraoperative injection, and according to the 2020 ERAS Society recommendations,³⁾ the administration of tranexamic acid is strongly recommended with a high level of evidence. Additionally, prior research has shown that routinely using drains in hip arthroplasty does not significantly reduce wound infections or hematomas. This has led to the conclusion that routine drain use is not strongly encouraged within the ERAS protocol.³,³⁷⁾ Therefore, when drains are not inserted, postoperative blood loss is reduced due to the tamponade effect. It is unsurprising that, as part of these efforts, the ERAS protocol group in this meta-analysis showed a lower rate of allogenic blood transfusion compared to the control group.

In terms of medical and surgical complications, our pooled analysis results showed that overall medical complications were significantly lower in the ERAS protocol group compared to the control group. However, there was no statistical difference in the incidence of surgical complications. A detailed subgroup analysis revealed that among medical complications, the incidence of pneumonia was particularly lower in the ERAS protocol group. According to our hypothesis, unlike other types of orthopedic surgeries or surgeries outside the orthopedic field, the recovery speed after hip surgery closely correlates with the patient’s level of ambulation. Implementing the ERAS protocol allows for early mobilization, which may have contributed to the reduction in pneumonia, one of the postoperative medical complications. In fact, it is already known that time to ambulation after hip surgery is closely associated with the development of new-onset pneumonia.³⁸⁾

Lastly, the LOS was significantly shorter in the ERAS group compared to the control group. Since reducing hospital length is a core goal of the ERAS protocol in surgical procedures,³⁹⁾ this result is expected. Although there may be differences in hospital stay policies between individual hospitals and across studies, this meta-analysis utilized a double-arm design. Therefore, within each individual study, hospital stay policies were relatively consistent, and we believe this minimized any potential bias in the overall trend showing that ERAS reduces LOS.

Although there may be differences in hospital stay policies between individual hospitals and across studies, this meta-analysis utilized a double-arm design. Therefore, within each individual study, hospital stay policies were relatively consistent, and we believe this minimized any potential bias in the overall trend showing that ERAS reduces LOS. Despite these consistent within-study policies, the practical application of ERAS protocols can differ substantially across healthcare systems due to variations in clinical expertise, patient profiles, and institutional resources. In resource-limited settings, implementing specialized interventions such as advanced nerve blocks, routine use of tranexamic acid, or intensive patient education programs may be more challenging. Consequently, the comprehensive ERAS protocol described in this meta-analysis might not be fully generalizable to all clinical contexts. Nevertheless, adopting key elements of ERAS (e.g., early mobilization, basic multimodal analgesia, and streamlined perioperative care pathways) within each hospital’s resource constraints can still offer measurable benefits in patient recovery and reduced hospital stays.

This study has some limitations. First, the ERAS protocol is not standardized, and the outcome measurements in each study were highly variable, which led to a smaller number of studies being included in the pooled analysis compared to the total number of articles reviewed. Additionally, the diversity in study designs and differences in patient populations across the included studies could also be considered limitations. Second, in the meta-analysis, there were items with high heterogeneity, which could potentially lead to bias in the interpretation of the results. Third, most of the included patients who underwent hip surgery underwent THA—among the 13 studies, 10 focused on THA. As a result, a thorough subgroup analysis for different types of hip surgeries could not be performed. The single study on bipolar hemiarthroplasty and the 2 studies on PFNA surgeries were insufficient in number to allow for meaningful subgroup analyses. Therefore, additional subgroup analyses were conducted only for THA surgeries. However, from a different perspective, this could be seen as an advantage, as it minimizes heterogeneity caused by different types of surgeries, thereby increasing the reliability of our pooled meta-analysis results for hip surgeries as a whole. Fourth, some variables in our meta-analysis demonstrated high heterogeneity. Previous studies have suggested that when the I² value exceeds 75%, the reliability of meta-analysis results may decrease.⁴⁰⁾ This could be considered a limitation of our study, indicating the need for further extended studies as more original research becomes available. Lastly, due to the nature of meta-analysis, the results were determined by the characteristics of the included studies, with a relatively high proportion of retrospective studies.

However, given that the importance of the ERAS protocol is increasingly recognized, this study is valuable as the first meta-analysis to integrate up-to-date data on its effectiveness across orthopedic hip surgery.

SUPPLEMENTARY MATERIAL

Supplementary material is available in the electronic version of this paper at the CiOS website, www.ecios.org.

Supplementary Material 1

Literature Search Algorithm and Results from Relevant Clinical Studies

Supplementary Material 2

Detailed ERAS Protocols