Use of a 3D virtual dynamic hip model to quantify the amount of osteoplasty required in femoroacetabular impingement patients

Objective: Compare required osteoplasty predicted by a 3D virtual dynamic hip model in femomacetabular impingement patients to actual osteoplasty performed. Materials and methods: Retrospective study on 20 consecutive FAI patients with a preoperative CT who underwent arthroscopy from October 2016 to September 2017. A 3D virtual dynamic hip model was created from the CT. The model displayed virtual osteoplasty depth required to restore physiologic range of motion on an osteoplasty map. Depths of virtual osteoplasty and actual osteoplasty at surgery were compared and correlated with alpha angle, lateral center edge angle, femoral version, and acetabular version. Results: Actual femoroplasty depth correlated with alpha angle (r = 0.85, p <= 0.001) and actual acetabuloplasty depth correlated with lateral center edge angle (r = 0.83, p < 0.001). Virtual osteoplasty depth did not correlate with alpha angle (p = 0.25), lateral center edge angle (p = 0.50), femoral version (p = 0.09), or acetabular version (p = 0.09). The 3D model predicted a mean virtual osteoplasty of 6.2 +/- 0.3 mm compared to mean actual osteoplasty of 5.9 +/- 1.1 mm. There was no significant difference between the two means (p = 0.26), though there was a significant difference in variance (p = 0.001). There was poor test reliability between virtual osteoplasty compared with actual osteoplasty (ICC = 0.30). Conclusion: 3D model predicted virtual osteoplasty depths varied with actual osteoplasty and was independent of 2D measurements.