Intraoperative Assessment of Combined Anteversion Using the Ranawat Technique with a Smartphone Application: A...

Optimal component positioning is critical for stability following total hip arthroplasty (THA). Combined anteversion (CA), incorporating both acetabular and femoral component orientation, has been proposed as a more reliable stability parameter than isolated acetabular positioning. However, accurate intraoperative assessment of CA without navigation remains challenging. This study prospectively evaluated the reliability and feasibility of surgeon-estimated CA using the Ranawat coplanar test compared with post-operative computed tomography (CT) measurements and correlated these findings with short-term functional outcomes.

This prospective observational study included 45 consecutive patients undergoing uncemented THA at a single tertiary care center. Intraoperative CA was estimated using the Ranawat coplanar test with smartphone-assisted goniometric measurement. Post-operative CT scans were used to calculate CA using Widmer's formula. Agreement between intraoperative and CT measurements was assessed using paired statistical analysis and the intraclass correlation coefficient (ICC). Functional outcomes were evaluated using the Harris Hip Score (HHS) over 6 months.

Mean intraoperative CA was 34.13° ± 8.39°, and mean CT-calculated CA was 36.01° ± 13.08°, with a mean difference of 1.88° (P = 0.177). Moderate agreement was observed (ICC = 0.65; 95% CI: 0.47-0.79). Mean HHS improved from 46.16 preoperatively to 90.87 at 6 months.

Intraoperative CA estimation using the Ranawat coplanar test demonstrated acceptable agreement with CT-based measurements.