Eligibility criteria
This meta-analysis was registered in PROSPERO (CRD42022375273). The current study followed PRISMA guidelines (Fig. 1)17. The research question was conducted following the PICOS strategy: (P) patients with clinical and radiologic diagnoses of femoroacetabular impingement syndrome; (I) interventions were arthroscopic surgery; (C) comparisons were more conservative procedures. More conservative procedures were considered the following: physiotherapy therapy or arthroscopic lavage alone; (O) outcomes were efficacy assessed by functional scores and safety evaluated by adverse events; (S) we included randomized controlled trials and meta-analyses to assess the quality of previous published level I evidence studies. The diagnosis of the femoroacetabular impingement syndrome was made clinically and by image (X-rays, MRI and/or CT). To maintain sample homogeneity and minimize potential confounding factors, we excluded studies that enrolled < 16 yo patients or those with systemic disease. Furthermore, studies that initially enrolled patients with osteoarthritis, one of the variables under investigation, were excluded. To ensure the precision of the sample size and estimates, we removed duplicate studies as well as those with incomplete data that could not be analyzed in the statistical program or did not share relevant variables, which could have hindered the meta-analysis.
Information sources
A systematic search of the literature using PubMed, EMBASE, Scopus, and the Cochrane Collaboration Library database was carried out. No date limit was specified. Language was not limited. Studies of interest that appeared in the references of the included studies in the first search were also evaluated by manual searching.
Search methods for identification of studies
We used the following search terms to search all trials registers and databases: “femoroacetabular impingement AND arthroscop*” the (Supplementary File 1). Two reviewers independently agreed on selection of eligible studies and achieved consensus on which studies to include. Regarding data extraction, two authors also independently reviewed the studies. If consensus was not reached, a third review author was asked to complete the data extraction form. We analyzed the records of the RCTs as well as their complementary material. We consulted expert opinion to assess which variables would be of most interest.
Data extraction and data items
The following baseline characteristics of each study were obtained: number of participants, type of study, journal, age, %female, %right hip, morphology (pincer, cam, or mixed), and follow-up. The lost follow-up rate and time since randomization were also analyzed. Funding and conflicts of interest were also evaluated. The primary efficacy outcomes were iHOT-33, HOS ADL (activities of daily living), and HOS S (sports). These measurements were taken at 6 months, and 12 months. The minimal clinically important difference (MCID) was included in the outcomes, based on previous studies that analyzed these scales. The MCID for iHOT-33, HOS ADL, and HOS S were six, 14, and 11 points, respectively18,19. We then assessed whether MCID was achieved using the confidence intervals of the mean difference between the experimental and control groups (yes/no).
Regarding safety outcomes, we assessed infection, numbness, additional surgery, osteoarthritis, and nerve injury. Studies evaluating complications were assessed up to the end of follow-up. Although some of the complications almost exclusively occur with arthroscopic surgery, since they are related to surgery and will not occur with physical therapy (e.g., infection), they were also compared to see if such a complication is more frequent. This is because some complications may potentially have negative consequences.
To assess the quality of the previously published meta-analyses, we extracted the variables required by the AMSTAR-2 scale. AMSTAR-2 is a tool that allows for a detailed assessment of meta-analyses and systematic reviews of randomized controlled trials (RCTs) and nonrandomized studies. AMSTAR-2 is a questionnaire with 16 domains and simple answers: yes (positive result), no (insufficient information), or partial yes (partial information to standard)20.
Assessment of risk of bias in included studies
The quality of the RCT was evaluated in accordance with Review Manager by two reviewers. The evaluation methods consisted of the following steps: (A) random sequence generation, (B) allocation concealment, (C) blinding patients and personnel, (D) blinding of data extraction, (E) incomplete outcome data, and (F) selective outcome reporting. The justification for the rating for each item is provided in the Supplementary File 2 (Fig. 2). In addition, we provide the risk of bias for each item within each forest plot to facilitate critical reading of the article.
Risk of bias (green = low risk; red = high risk; yellow = unknown).
Assessment of results
The meta-analysis was performed using the Review Manager 5.4 software package provided by the Cochrane Collaboration. For dichotomous variables, odds ratios with a confidence interval (CI) of 95% were calculated. In this study, the odds ratio was preferred over the risk ratio because of its ease of interpretation and usefulness when the data are skewed. This decision was considered appropriate given the low frequency of the outcome of interest and the relatively infrequent occurrence of complications. The mean difference (MD) and the 95% CI were calculated for the continuous variables. Heterogeneity was checked with both the chi2 and the I2 test. I2 varies from 0 to 100%, considering the values of 25, 50 and 75% as low, moderate, and high heterogeneity, respectively. A fixed effects model was adopted if there was no statistical evidence of heterogeneity, and a random effects model was adopted if significant heterogeneity was observed. WebPlotDigitizer version 13.1.4 was used to obtain accurate information from the figures in the articles.
Risk of bias across the studies
We assessed the possibility of publication bias by evaluating a funnel plot (Review Manager 5.4) of the trial mean differences for asymmetry, which can result from the non-publication of small trials with negative results. We acknowledge that other factors, such as differences in trial quality or true study heterogeneity, could produce asymmetry in funnel plots.
Additional analyses
A sensitivity analysis was also carried out using Review Manager 5.4 eliminating the top-weight study from the comparisons of all outcomes.
Regression analysis was also performed to examine the impact of the moderating variables in the effect size study. Different moderators and demographic variables were also included. Qualitative variables were assigned a numerical value to carry out the analysis. The dependent variables were efficacy outcomes (iHOT-33 and HOS ADL), whereas the independent variables were morphology, risk of bias, loss to follow-up, time since randomization, and direct funding from arthroscopic foundations or societies. Regression analysis using ordinary least squares method was conducted using the SPSS package v. 24.0 (IBM, USA), and p < 0·05 was considered statistically significant. Thus, to complement this analysis, a subgroup analysis of the aforementioned variables was performed using the Review Manager 5.4 software package.
The GRADE system was used to assess the quality of the evidence and grade the strength of the recommendations, the Grade of Recommendation, Assessment, Development, and Evaluation (GRADE) system was used using GRADEpro. This system assesses study design, risk of bias, inconsistency, indirectness, imprecision, and summary of findings21.