Article

Patellofemoral Pain Syndrome (PFPS) is a common musculoskeletal complaint. The
presence of a delay between vastus medialis obliquus (VMO) and vastus lateralis
(VL) muscle onset has been suggested in the literature as a possible cause of
PFPS, with poor agreement amongst authors on the value of the delay. In this
study we computed the delay in the activation of VMO and VL in 15 PFPS patients
and 20 age-matched controls (Ctrls) during the following tasks: sit to stand,
stand to sit, squat, step up and step down. Activation instants were detected
from surface EMG data by a double-threshold statistical detector. In order to
compare the muscle activity throughout the task, we computed the delay between
the instants in which the VMO and VL normalised envelopes reached subsequent
normalised amplitude levels, until the envelope peak. In all investigated tasks
but sit to stand, the onset delay was lower or equal then 0.02s, without group
differences. Similarly, no differences between Ctrls and PFPS timing were found
throughout all tasks, until the peak. Our results do not support the hypothesis
that an onset delay between VMO and VL can be one of the causes of PFPS.
CI - Copyright (c) 2010. Published by Elsevier B.V.

Langue : ANGLAIS