Quantifying Pelvic Motion During Total Hip Arthroplasty Using a New Surgical Navigation Device.

Area of Science:

• Orthopedic Surgery
• Surgical Navigation
• Biomechanics

Background:

• Accurate acetabular cup positioning is critical in total hip arthroplasty (THA).
• Undetected patient motion during THA can lead to cup malpositioning, increasing risks of dislocation and revision surgery.
• Limited literature exists on the magnitude of patient motion during THA.

Purpose of the Study:

• To analyze intraoperative pelvic motion during THA using a novel navigation device.
• To quantify the extent of patient movement in terms of pitch and roll.
• To assess the implications of this motion on acetabular cup placement.

Main Methods:

• Utilized a novel navigation device with an integrated accelerometer to measure intraoperative pelvic motion in 2 orthogonal degrees of freedom.
• Analyzed data from 99 total hip arthroplasty cases performed between February and September 2016.
• Quantified patient motion in terms of pitch and roll angles.

Main Results:

• Mean pitch was 2.7° (SD 2.2°), with 21% of patients exhibiting >4° pitch.
• Mean roll was 7.3° (SD 5.5°), with 69% of patients exhibiting >4° roll and 25% exhibiting ≥10° roll.
• Significant intraoperative pelvic roll was observed in a substantial proportion of patients.

Conclusions:

• While most intraoperative motion is <4°, significant pelvic roll occurs in many THA patients.
• Failure to account for substantial pelvic roll can lead to acetabular cup malpositioning outside the planned safe zone.
• Further research is needed to determine the precise impact of this motion on cup position, leg length, and offset.