Changes in sagittal component alignment alters patellar kinematics in TKA: an in vitro study

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Biomedical Engineering

Background:

• Anterior knee pain is a common complication following total knee arthroplasty (TKA).
• Incorrect component alignment, particularly of the patellofemoral joint, is a primary cause of this pain.
• While coronal and axial alignment are well-studied, the effect of sagittal alignment on patellar kinematics remains unclear.

Purpose of the Study:

• To investigate the influence of femoral and tibial component sagittal alignment on patellar kinematics after TKA.
• To determine if sagittal component alignment affects patellar tracking and contributes to anterior knee pain.

Main Methods:

• Ten cadaveric knee specimens underwent TKA using a computer navigation system.
• The femoral component was implanted with 0° or 5° of flexion in different knees.
• Patellar kinematics were tracked using a navigation system and correlated with component alignment.

Main Results:

• Sagittal component alignment demonstrated a significant effect on patellar mediolateral shift (p < 0.05).
• No significant influence was observed on patellar epicondylar distance, rotation, or tilt.
• This suggests a specific impact on patellar translation rather than other kinematic parameters.

Conclusions:

• Sagittal component alignment is a critical factor influencing patellar kinematics in TKA.
• Intraoperative consideration of sagittal alignment is recommended to optimize patellar tracking and potentially alleviate anterior knee pain.