Q-angle and J-sign: indicative of maltracking subgroups in patellofemoral pain.
Mechanical factors related to patellofemoral pain syndrome and maltracking are poorly understood. Clinically, the Q-angle, J-sign, and lateral hypermobility commonly are used to evaluate patellar maltracking. However, these measures have yet to be correlated to specific three-dimensional patellofemoral displacements and rotations. Thus, we tested the hypotheses that increased Q-angle, lateral hypermobility, and J-sign correlate with three-dimensional patellofemoral displacements and rotations. We also determined whether multiple maltracking patterns can be discriminated, based on patellofemoral displacements and rotations. Three-dimensional patellofemoral motion data were acquired during active extension-flexion using dynamic MRI in 30 knees diagnosed with patellofemoral pain and at least one clinical sign of patellar maltracking (Q-angle, lateral hypermobility, or J-sign) and in 37 asymptomatic knees. Although the Q-angle is assumed to indicate lateral patellar subluxation, our data supported a correlation between the Q-angle and medial, not lateral, patellar displacement. We identified two distinct maltracking groups based on patellofemoral lateral-medial displacement, but the same groups could not be discriminated based on standard clinical measures (eg, Q-angle, lateral hypermobility, and J-sign). A more precise definition of abnormal three-dimensional patellofemoral motion, including identifying subgroups in the patellofemoral pain population, may allow more targeted and effective treatments.
National Institutes of Health, Building 10 CRC, Room 1-1469, 10 Center Drive MSC 1604, Bethesda, MD 20892-1604, USA. fsheehan@cc.nih.gov
Frances T
FT
Sheehan
Aditya
A
Derasari
Kenneth M
KM
Fine
Timothy J
TJ
Brindle
Katharine E
KE
Alter
D000328:Adult; D001696:Biomechanical Phenomena; D015331:Cohort Studies; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000473:pathology / Q000503:physiopathology*; D007593:Joint Instability / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D057071:Patellofemoral Joint / Q000473:pathology / Q000503:physiopathology*; D046788:Patellofemoral Pain Syndrome / Q000473:pathology / Q000503:physiopathology*; D016059:Range of Motion, Articular