When and How Is Patella Tracking Best Assessed in Total Knee Arthroplasty Surgery?

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Biomedical Engineering

Background:

• Soft tissue balancing is often underestimated in total knee arthroplasty (TKA).
• Accurate assessment of patellofemoral joint (PFJ) kinematics is essential for successful TKA outcomes.
• The impact of tourniquet use and retinacular integrity on PFJ tracking requires further elucidation.

Purpose of the Study:

• To evaluate the effect of tourniquet inflation on PFJ tracking during TKA.
• To determine the impact of patella retinacular reconstruction on PFJ kinematics intraoperatively.
• To compare PFJ tracking between the "no thumb technique" and a two-suture retinacular reconstruction method.

Main Methods:

• Intraoperative assessment of PFJ kinematics in 20 consecutive TKA patients using a novel tracking system.
• Measurements were taken with the "no thumb technique" and after retinacular reconstruction with two positional sutures.
• Measurements were repeated after tourniquet deflation to assess its impact.

Main Results:

• Tourniquet inflation did not significantly affect patella tracking (mean translation 0.9 mm, p=0.15).
• Patella retinacular reconstruction resulted in significant medialization (mean 5.5 mm, p<0.0001) compared to the "no thumb technique."
• Retinacular reconstruction improved patella tracking, achieving a mean medialization of 15%.

Conclusions:

• Tourniquet use has a negligible effect on patella tracking in TKA.
• Patella retinacular reconstruction using two positional sutures markedly enhances patella tracking and PFJ alignment.
• Routine use of two positional sutures for retinacular restoration is recommended for reproducible PFJ kinematic assessment before patella component trial.