Visual perioperative estimation of correction of the acetabular fragment in periacetabular osteotomies is sufficient but outliers exist

Abstract

Background:

Periacetabular osteotomy (PAO) is a well-established surgical treatment of symptomatic developmental dysplasia of the hip in young patients by improving the lateral centre-edge angle (LCEA) and the acetabular index (AI). Hence, the correction of the acetabular fragment is a hallmark of the PAO procedure.

Purpose:

To evaluate the efficacy of fluoroscopy-guided visual estimation of the correction of the fragment during PAO.

Methods:

49 patients undergoing PAO were enrolled. The surgeons (3) were asked to visual assess the perioperative LCEA and AI. Perioperative assessments were compared with perioperative and postoperative measurements. Interobserver variation was assessed by regression analysis. Bland-Altman analysis was used to determine correlation between visual assessment and measurements.

Results:

Mean correction of the LCEA was 11.1° (-4–23.5°) and the average AI correction was -10.7° (-20– 4°). The interobserver agreement was high for LCEA (R² = 0.83) and acceptable for AI (R² = 0.60). Visual estimation significantly overestimated the correction of the LCEA angle by 1.5° (95% CI, 1.0–1.9) and significantly overestimated AI by 0.31° (95% CI, 0.22–0.39) compared with the postoperative result. Retrospective measurements on the perioperative x-rays showed that this would have led to a significant underestimation of the correction of LCEA of 1.4° (95% CI 1.0–1.9) and overestimation of AI by 2.7° (95% CI, 1.9–3.5).

Conclusions:

Perioperative visual estimation is on average sufficient for assessing the postoperative correction of LCEA and AI in PAO. Outliers are however observed.