Lateral prosthetic trochlear angle deviation is common and clinically safe after robotic functionally aligned total...

Area of Science:

• Orthopedic surgery
• Biomechanical analysis
• Arthroplasty research

Background:

• Patellofemoral kinematics and outcomes in total knee arthroplasty (TKA) are influenced by the alignment of the prosthetic trochlear angle (PTA) and quadriceps vector (QV).
• Understanding this relationship is crucial for optimizing TKA results.

Purpose of the Study:

• To investigate the correlation between the deviation of the PTA from the QV and patient-reported outcomes.
• To evaluate outcomes in image-based, robotic-assisted, functionally aligned TKAs (FA-TKAs).

Main Methods:

• Retrospective analysis of 237 patients undergoing robotic-assisted FA-TKA with at least 2 years of follow-up.
• Measurement of PTA-QV deviation on post-operative radiographs.
• Assessment of clinical outcomes using Knee Society Score (KSS), KSS-Functional (KSS-F), and Forgotten Joint Score (FJS).

Main Results:

• Mean PTA deviation from QV was 3.8° ± 2.4°, predominantly lateral.
• Only 2.9% of knees showed medial deviation.
• PTA deviation correlated with the hip-knee-ankle (HKA) angle (p<0.001) but not with clinical scores.

Conclusions:

• In robotic-assisted FA-TKAs, PTA typically deviates laterally from the QV without impacting patient outcomes.
• This lateral deviation reflects overall coronal alignment and is biomechanically safe.
• Optimal post-operative knee function and patient satisfaction are maintained.