Q-Angle
Definition
The angle formed between a line from the ASIS to the center of the patella and a line from the center of the patella to the tibial tuberosity. Normal Q-angle is approximately 12-15 degrees in males and 15-20 degrees in females. The Q-angle quantifies the lateral pull on the patella during quadriceps contraction.
Clinical Significance
An increased Q-angle increases the lateral pull on the patella, contributing to patellar maltracking, patellofemoral pain, and anterior knee pain. Women tend to have larger Q-angles due to wider pelves, which partially explains the higher incidence of ACL injuries and patellofemoral syndrome in female athletes. The Q-angle is influenced by hip width, femoral rotation, tibial torsion, and foot pronation -- making it a downstream indicator of multiple structural factors.
How AKMI Assesses This
AKMI estimates Q-angle through standing frontal photography and landmark identification. The measurement is correlated with hip rotation, knee alignment, and foot pronation data to determine whether the Q-angle is driven by proximal (hip) or distal (foot/tibia) factors.
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