Leg length and offset measures with a pinless femoral reference array during THA

Area of Science:

• Orthopedic Surgery
• Medical Imaging
• Biomechanical Engineering

Background:

• Traditional computer-assisted navigation in total hip arthroplasty (THA) relies on bony fixation, posing risks like fracture, infection, and pin loosening.
• Accurate intraoperative assessment of leg length (LL) and offset (OS) is crucial for successful THA outcomes.

Purpose of the Study:

• To evaluate the accuracy of a novel pinless femoral reference system for intraoperative LL/OS assessment during THA.
• To compare measurements from the pinless system with CT-based assessments.

Main Methods:

• A pinless femoral reference system and an imageless measurement algorithm were used for LL/OS assessment in 17 cadaver specimen hips during simulated THA.
• Preoperative and postoperative CT scans were performed. Radiographic LL/OS changes were determined by two independent investigators using image processing software.

Main Results:

• High intra- and inter-observer correlation (≥0.95) was found for CT-based LL/OS measurements.
• The pinless system demonstrated mean differences of less than 1 mm compared to CT measurements.
• A strong correlation was observed between the pinless system's LL/OS values and CT-derived measurements.

Conclusions:

• The novel pinless femoral reference system provides accurate intraoperative assessment of leg length and offset changes during total hip arthroplasty.
• This pinless approach offers a viable alternative to traditional methods, potentially reducing complications associated with bony fixation.