The a angle: a quantitative measurement of patella alignment and realignment.

This case study introduces a clinical measurement of patellar glide, tin, and rotation, and defines a quantitative measurement called the A angle. An 11-year-old female with patellofemoral pain is treated using a protocol that includes a technique to align the patella through taping, stretching the lateral structures, and strengthening using functional training and isokinetics, with emphasis on the vastus medialis obliquus. The A angle may be a sensitive clinical indicator of patellofemoral pathomechanics. J Orthop Sports Phys Ther 1990;12(6):237-242.