FP12.7 Imageless Navigation in Hip Resurfacing Arthroplasty: Accuracy of Cup Positioning and Leg Length Restoration
Abstract
Abstract ICLA12 - The Chondral Masterclass: Advanced Scaffolds, Orthobiologic Realities, and Young THA, Auditorium B (BMCC Level 1), October 9, 2026, 10:30 - 12:30 Background Hip Resurfacing Arthroplasty (HRA) is a technically demanding procedure in which precise component positioning is critical to minimize complications and reduce wear. This study evaluates the accuracy of the Navisuisse® handheld imageless navigation system for acetabular cup positioning (inclination and anteversion) and for assessing intraoperative changes in femoral offset and leg length. Methods Fifteen consecutive patients were treated with HRA using intra-operative imageless navigation. The target acetabular cup position was 40° inclination and 20° anteversion, adjusted according to the RAIL criteria. Postoperative radiographs at day 1 and 6 weeks were analyzed for cup inclination (CI), anteversion (CA), leg length (LL), and offset changes. Intraoperative navigation data were compared with postoperative measurements. Accuracy was expressed as mean absolute difference and agreement assessed using Lin’s concordance correlation coefficient (CCC). Results All acetabular components were positioned within the predefined target zone. Mean intraoperative vs postoperative values were: CI 43.0° vs 42.3°, CA 18.9° vs 18.5°, LL +1.86 mm vs +1.36 mm, and offset -3.43 mm vs -1.21 mm. CCC indicated good agreement for LL (0.755) and offset (0.764), moderate for CI (0.397), and low for CA (0.276). Accuracy thresholds were achieved in 100% of cases for LL (≤ ±2 mm), 86.7% for offset (≤ ±5 mm), 80.0% for CI (40° ±5°), and 93.3% for CA (15° ±10°). Patient satisfaction was high (73% “Excellent,” 27% “Very Good”), and mean length of stay was 2 days. Conclusion The Navisuisse® system demonstrated excellent accuracy for cup positioning and leg length restoration in HRA. Offset restoration was generally reliable, with minor deviations. Imageless navigation represents a valuable adjunct to improve surgical precision, optimize biomechanics, and support consistent outcomes in hip resurfacing procedures.