The Sacro-femoral-pubic Angle Is Unreliable to Estimate Pelvic Tilt: A Meta-analysis

• Published in: Clinical orthopaedics and related research 2023-10, Vol.481 (10), p.1928-1936
• Main Authors: Chai, Yuan, Boudali, A. Mounir, Khadra, Sam, Walter, William L.
• Format: Article
• Language: English
• Subjects: Adult; Age; Bone surgery; Clinical Research; Correlation analysis; Female; Femur; Femur - diagnostic imaging; Humans; Male; Meta-analysis; Patients; Pelvis - diagnostic imaging; Pubic Bone; Radiography; Reproducibility of Results; Retrospective Studies; Sacrum; Sensitivity analysis; Sex; Therapeutic applications; Young Adult
• ISSN: 0009-921X; 1528-1132; 1528-1132
• DOI: 10.1097/CORR.0000000000002650

The accurate measurement of pelvic tilt is critical in hip and spine surgery. A sagittal pelvic radiograph is most often used to measure pelvic tilt, but this radiograph is not always routinely obtained and does not always allow the measurement of pelvic tilt because of problems with image quality or patient characteristics (such as high BMI or the presence of a spinal deformity). Although a number of recent studies have explored the correlation between pelvic tilt and the sacro-femoral-pubic angle using AP radiographs (SFP method), which aimed to estimate pelvic tilt without a sagittal radiograph, disagreement remains about whether the SFP method is sufficiently valid and reproducible for clinical use. The purpose of this meta-analysis was to evaluate the correlation between SFP and pelvic tilt in the following groups: (1) overall cohort, (2) male and female cohort, and (3) skeletally mature and immature cohorts (young and adult groups, defined as patients older or younger than 20 years). Additionally, we assessed (4) the errors of SFP-estimated pelvic tilt angles and determined (5) measurement reproducibility using the intraclass correlation coefficient. This meta-analysis was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered in PROSPERO (record ID: CRD42022315673). PubMed, Embase, Cochrane, and Web of Science were screened in July 2022. The following keywords were used: sacral femoral pubic, sacro femoral pubic, or SFP. The exclusion criteria were nonresearch articles such as commentaries or letters and studies that only investigated relative pelvic tilt rather than absolute pelvic tilt. Although the included studies had different patient recruitment strategies, study quality-wise, they all used an adequate amount of radiographs for landmark annotation and applied a correlation analysis for the relationship between the SFP angle and pelvic tilt. Thus, no risk of bias was found. Participant differences were mitigated via subgroup and sensitivity analyses to remove outliers. Publication bias was assessed using the p value of a two-tailed Egger regression test for the asymmetry of funnel plots, as well as the Duval and Tweedie trim and fill method for potential missing publications to impute true correlations. The extracted correlation coefficients r were pooled using the Fisher Z transformation with a significance level of 0.05. Nine studies were included in the meta-analysis, tota