Article

Previous studies focused on describing successful sit-to-stand (STS)
performance in patients with Parkinson disease (PD).
Little is known about why
these patients fail to perform this transfer activity. Objective This study aimed
to determine the role of dynamic stability and limb support in governing
successful STS performance in patients with PD and to determine the limits of
recovery for discriminating between successful and failed STS trials.
This was a cross-sectional study. METHODS: Twenty-eight patients with PD were
instructed to perform the STS task. Kinematic data on 18 successful trials and 14
failed trials (when the patients fell backward) were collected with a motion
analysis system. Dynamic stability was determined by the anteroposterior position
of the body's center of mass (COM) relative to the base of support (BOS) and by
the anteroposterior velocity of the COM relative to the BOS
(Velocity(COM/BOS,AP)). Limb support was characterized by the hip height
(Height(hip)). RESULTS: /b> The findings revealed no between-group ("risers"
versus "fallers") differences in dynamic stability. The fallers shifted their COM
in a significantly more anterior position to compensate for their lower
Velocity(COM/BOS,AP) at seat-off. It was in the vertical direction that the
fallers had significantly reduced peak COM velocity (Velocity(COM,vertical)) and
lower corresponding Height(hip) than the risers. Results of a stepwise regression
model showed that Velocity(COM/BOS,AP) and Height(hip) at the instant of peak
Velocity(COM,vertical) could best predict the STS outcome (success versus
failure), with an overall prediction accuracy of 87.5%. The limit differentiating
successful from failed STS trials was: Height(hip)=-0.814 Velocity(COM/BOS,AP) +
0.463. Limitations All of the patients were community dwelling and had a moderate
level of disease severity.
The results cannot be generalized to those who are
institutionalized or with advanced PD. CONCLUSIONS: Limb support and ill-timed
peak forward COM velocity, rather than dynamic stability, play the dominant roles
in determining successful STS performance in patients with PD.

Langue : ANGLAIS