Q-angle influences tibiofemoral and patellofemoral kinematics

Yasayuki Mizuno, Masaru Kumagai, Stephen M. Mattessich, John J. Elias, Navin Ramrattan, Andrew J. Cosgarea, Edmund Y.S. Chao

Research output: Contribution to journalArticle

Abstract

Numerous surgical procedures have been developed to correct patellar tracking and improve patellofemoral symptoms by altering the Q-angle (the angle between the quadriceps load vector and the patellar tendon load vector). The influence of the Q-angle on knee kinematics has yet to be specifically quantified, however. In vitro knee simulation was performed to relate the Q-angle to tibiofemoral and patellofemoral kinematics. Six cadaver knees were tested by applying simulated hamstrings, quadriceps and hip loads to induce knee flexion. The knees were tested with a normal alignment, after increasing the Q-angle and after decreasing the Q-angle. Increasing the Q-angle significantly shifted the patella laterally from 20° to 60° of knee flexion, tilted the patella medially from 20° to 80° of flexion, and rotated the patella medially from 20° to 50° of flexion. Decreasing the Q-angle significantly tilted the patella laterally at 20° and from 50° to 80° of flexion, rotated the tibia externally from 30° to 60° of flexion, and increased the tibiofemoral varus orientation from 40° to 90° of flexion. The results show that an increase in the Q-angle could lead to lateral patellar dislocation or increased lateral patellofemoral contact pressures. A Q-angle decrease may not shift the patella medially, but could increase the medial tibiofemoral contact pressure by increasing the varus orientation.

Original languageEnglish (US)
Pages (from-to)834-840
Number of pages7
JournalJournal of Orthopaedic Research
Volume19
Issue number5
DOIs
StatePublished - Jan 1 2001

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

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