JOA - 2026-04-22 - Journal Article
Pelvic Tilt Reproducibility Using Fluoroscopy in Direct Anterior Approach Total Hip Arthroplasty.
Zepeda K, Yared T, Burgio C, Persaud S, Lyman S, Vigdorchik JM, Debbi EM
Topics
Key Takeaway
Intraoperative fluoroscopy during DAA THA reproduced standing pelvic tilt within ±7° in only 76% of patients, with a low correlation (r=0.294) between preoperative standing and intraoperative AP pelvic tilt.
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Summary
This study asked whether intraoperative fluoroscopy during DAA THA accurately recreates preoperative standing pelvic tilt, using AP pelvic tilt and SFP angle measured on preoperative EOS and intraoperative fluoroscopic images in 325 patients. Standing PT was reproduced within ±7° in 76% and within ±13° in 95% of patients. However, the correlation between preoperative standing and intraoperative AP PT was poor (r=0.294), and the standing-to-supine SFP change correlated only moderately with AP PT change (r=0.422), indicating that visual fluoroscopic assessment alone introduces clinically meaningful variability in functional cup positioning.
Key Limitation
The study does not report actual postoperative cup anteversion or dislocation outcomes, so the clinical consequence of the observed pelvic tilt recreation error on component positioning accuracy and instability rates remains unestablished.
Original Abstract
BACKGROUND
Precise acetabular component positioning depends heavily on accurately recreating pelvic tilt (PT) during total hip arthroplasty (THA). The direct anterior approach (DAA) facilitates intraoperative fluoroscopy for real-time assessment, yet the accuracy of recreating preoperative standing PT intraoperatively remains unexplored. This study evaluated the precision of intraoperative PT recreation between pre- and intraoperative antero-posterior (AP) radiographic images during DAA THA.
METHODS
This retrospective cohort included 325 patients undergoing primary unilateral DAA THA by a single surgeon between July 2022 and July 2024. Sagittal pelvic tilt was measured on preoperative EOS radiographs in both standing and sitting positions. There were two validated parameters, antero-posterior PT and the sacro-femoral-pubic (SFP) angle, that were then calculated for both standing as well as intraoperative fluoroscopic images. There were two blinded observers who independently performed all measurements using the intraclass correlation coefficient (ICC > 0.80). The primary outcome was the proportion of patients in whom intraoperative PT was reproduced within ± 7.0 and ± 14.0° of standing values, thresholds corresponding to approximately 5.0 and 10.0° of anteversion inaccuracy. The secondary outcomes assessed correlations between pre- and intraoperative alignment parameters.
RESULTS
Both AP PT and the Delta SFP (standing-to-sitting) angle demonstrated moderate-to-strong correlations with sagittal standing PT and Delta PT, confirming measurement accuracy prior to intraoperative analysis. Intraoperative fluoroscopy reproduced standing PT within ± 7.0° in 76% of patients and within ± 13.0° in 95%. However, preoperative standing and intraoperative AP PT demonstrated low correlation (r = 0.294), indicating substantial variability. The change in SFP (standing-to-supine) demonstrated moderate correlation with the change in AP PT (r = 0.422), further reflecting the limited precision of the PT recreation.
CONCLUSION
Visual fluoroscopic recreation of standing PT during DAA THA demonstrated moderate accuracy, with three-quarters of patients achieving clinically relevant precision. Variability in reproducing functional pelvic tilt suggests that visual assessment alone may benefit from adjunctive verification to improve consistency in acetabular positioning.