Does patella position influence ligament balancing in total knee arthroplasty?

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering

Background:

• Accurate joint gap assessment is critical for successful total knee arthroplasty (TKA).
• Patellar positioning during TKA can potentially affect mediolateral gap measurements.

Purpose of the Study:

• To comparatively measure in vivo joint gaps in three distinct patellar positions: reduced, subluxated, and everted.
• To evaluate the influence of intraoperative patellar positioning on gap balancing during TKA.

Main Methods:

• Prospective study of 50 knees undergoing TKA with a navigation-assisted gap-balancing technique.
• Utilized an offset-type, force-controlled spreader system for precise mediolateral gap measurements at 0° and 90° knee flexion.
• Analyzed correlations between gap differences and demographic, preoperative, and intraoperative data.

Main Results:

• Patellar eversion resulted in smaller joint gaps compared to the reduced patella position, particularly at 90° flexion.
• A statistically significant difference was noted in the lateral gap with patellar eversion versus reduction at 90° flexion (p < 0.05).
• Variability in gap measurements was observed, with patellar subluxation and eversion causing notable changes in 24% and 66% of knees, respectively.

Conclusions:

• Intraoperative patellar positioning directly impacts joint gap measurements in TKA.
• Maintaining the patella in a reduced position is essential for reliable and accurate gap balancing.
• These findings underscore the importance of standardized patellar management during TKA surgery.