Pelvic Position at Cup Placement Compared With Intraoperative Pelvic Motion in the Lateral Decubitus Position

Area of Science:

• Orthopedic Surgery
• Surgical Navigation
• Biomechanics

Background:

• Accurate acetabular cup placement is critical for total hip arthroplasty (THA) outcomes.
• Pelvic position during surgery is influenced by both initial patient positioning and intraoperative movement.
• Understanding these factors is essential for optimizing surgical accuracy.

Purpose of the Study:

• To characterize and compare pelvic position at cup placement with intraoperative pelvic motion during THA.
• To determine the relative impact of initial pelvic position versus intraoperative motion on final cup placement.

Main Methods:

• Utilized an augmented reality-based portable hip navigation system in 86 primary THA cases.
• Measured pelvic positions (pitch and roll) in the supine and lateral decubitus positions.
• Recorded pelvic orientation at initial set-up and final cup placement.

Main Results:

• Significant differences were observed between pelvic position at cup placement and intraoperative pelvic motion for both pitch and roll angles.
• Greater variations in pitch and roll were noted at the time of cup placement.
• Initial set-up position more closely influenced pitch, while intraoperative motion impacted roll.

Conclusions:

• Pelvic position at cup placement is distinct from intraoperative pelvic motion.
• Both initial patient positioning and intraoperative pelvic motion contribute uniquely to the final acetabular cup position.
• These findings highlight the complex interplay of factors affecting THA accuracy.