Main determinants of weight-bearing asymmetry in hemiplegic stroke patients.

OBJECTIVE: Weight-bearing asymmetry (WBA) at the expense of the paretic side concerns 60% of stroke patients. WBA is associated with poor functional prognosis especially in terms of gait performance [1,2]. The primary objective was to assess the determinants of WBA in stroke patients from clinical and instrumental data.

MATERIAL/PATIENTS AND METHODS: The sensitivity (EmNSA), motricity (Fugl-Meyer motor), spatial neglect and visual perception of verticality (VPV) were evaluated in 20 stroke patients (age: 53.3±15.3 years; paresis D/G: 9/11) at least 3 months post-stroke and 20 control subjects. WBA and postural instability, as assessed by velocity of the center of pressure (VelCP), were measured eyes open with a force platform (Feetest, Technoconcept), synchronized with a three-dimensional kinematic analysis (OptiTrack motion capture system) of the pelvis and trunk.

RESULTS: Nine patients showed no WBA like in controls, 9 had a WBA to the expense of the paretic side (15.3% of body weight) and 2 to the expense of the non-paretic side (14.1% of body weight). The VPV was unaltered in both groups. In patients, the pelvis translation was increased on the overloaded side (1±1.6° vs. -0.1±0.6°, P<0.05) and was highly positively correlated with the WBA (r=0.85) and negatively with the Fugl-Meyer score (r=-0.71). Stepwise multiple linear regression revealed four predictors of WBA (adjusted r(2)=0.85): Fugl-Meyer, pelvis translation, VelCP and VPV.

DISCUSSION - CONCLUSION: From a biomechanical perspective, the main determinant of WBA seems to be the pelvis translation toward the overloaded side, itself being strongly associated with motor impairment and postural instability, with the possible participation of a VPV disorder.