Factors affecting the rectus femoris-patellar tendon Q-angle, measured using a computed tomographic scan

Area of Science:

• Orthopedic biomechanics
• Medical imaging analysis
• Human anatomy

Background:

• The Q-angle, the angle between the rectus femoris muscle and the patellar ligament, is a critical parameter in assessing knee alignment.
• Previous methods for Q-angle measurement have limitations.
• Understanding factors influencing Q-angle is essential for diagnosing and managing patellar instability.

Purpose of the Study:

• To investigate the influence of lateral and medial bone shifts at specific anatomical points on the Q-angle.
• To identify key factors contributing to altered Q-angles in patients with recurrent patellar dislocation.

Main Methods:

• Utilized computed tomography (CT) to measure the Q-angle and associated bone shifts.
• Compared 83 patients with recurrent patellar dislocation against 55 healthy controls.
• Analyzed shifts in the anterosuperior iliac spine (ASIS), anteroinferior iliac spine (AIIS), femoral condyle groove, and tibial tubercle.

Main Results:

• Significant lateral shifts were observed at the ASIS (P < 0.01) and AIIS (P < 0.05) in the dislocation group compared to controls.
• A medial shift was noted in the femoral condyle groove (P < 0.001) in the dislocation group.
• A pronounced lateral shift in the tibial tubercle (P < 0.0001) was the most significant finding in patients with patellar dislocation.

Conclusions:

• Lateral tibial tubercle shift is a primary factor influencing the Q-angle as measured by CT.
• These anatomical variations provide insights into the biomechanical basis of recurrent patellar dislocation.
• CT-based Q-angle measurement and analysis of bone shifts offer valuable diagnostic information.