For preoperative simulations of hip range of motion to be useful in predicting complications after total hip arthroplasty (THA), the factors that could affect post-operative function must be considered including, but not limited to, bony impingement, pelvic position, and implanted vs. planned differences. This study retrospectively simulates ranges of motion to prosthetic and bony impingement of THA patients with known planned and implanted component positions and pelvic tilt to determine the factors and needs to accurately simulate range of motion preoperatively.Twenty-two (22) anterolateral, cementless total hip arthroplasties were performed using robotic-arm assisted technology which allowed capture of the implanted stem version and position in addition to robotic-assisted cup placement to plan. With the known implanted positions and preoperative 3-dimentional (3D) bone models, six (6) hip maneuvers were virtually simulated in custom software. Correlations were evaluated between planned and implanted component positions, pelvic tilt, ranges of motion, and patient-reported outcomes.Average ranges of motion to impingement were similar to those of previous simulation and navigation studies. Supine tilt varied from -10 ̊ (posterior) to 15 ̊ (anterior) with an average of 3.4±6.6 ̊. Very little correlation was seen between native or planned stem version and implanted stem version. Correlations were seen between some maneuvers such as internal rotation (IR) at 90 degrees flexion (F) (IR@90F) and combined component version and pelvic tilt. Bony impingement occurred during IR@90F in 9 of the 22cases. Pelvic tilt assessment, bony impingement detection, better prediction of implanted component position or the ability to execute a plan, such as robotically, would all provide a more accurate pre-operative simulation of the post-operative patient’s function.
Arthroscopic treatment of anteromedial ankle impingement
