Article

In hemiplegic gait the paretic lower limb provides less muscle power and shows a
briefer stance compared with the unaffected limb.
Yet, a longer stance and a
higher power can be obtained from the paretic lower limb if gait speed is
increased. This supports the existence of a 'learned non-use' phenomenon, similar
to that underlying some asymmetric impairments of the motion of the eyes and of
the upper limbs. Crouch gait (CG) (bent-hip bent-knee,
about 30 degrees minimum
knee flexion) might be an effective form of 'forced-use' treatment of the paretic
lower limb. It is not known whether it also stimulates a more symmetric muscle
power output. Gait analysis on a force treadmill was carried out in 12 healthy
adults and seven hemiplegic patients (1-127 months after stroke, median: 1.6).
Speed was imposed at 0.3 m/s. Step length and single and double stance times,
sagittal joint rotations, peak positive power, and work in extension of the hip,
knee, and ankle (plantar flexion), and surface electromyography (sEMG) area from
extensor muscles during the generation of power were measured on either side
during both erect and crouch walking. Significance was set at P less than 0.05;
corrections for multiplicity were applied. Patients, compared with healthy
controls, adopted in both gait modalities and on both sides a shorter step length
(61-84%) as well as a shorter stance (76-90%) and swing (63-83%) time. As a rule,
they also provided a higher muscular work (median: 137%, range: 77-250%)
paralleled by a greater sEMG area (median: 174%, range: 75-185%). In erect gait,
the generation of peak extensor power across hip, knee, and ankle joints was in
general lower (83-90%) from the paretic limb and higher (98-165%) from the
unaffected limb compared with control values. In CG, peak power generation across
the three lower limb joints was invariably higher in hemiparetic patients:
107-177% from the paretic limb and 114-231% from the unaffected limb. When gait
shifted from erect to crouch, only for hemiplegic patients, at the hip, the paretic/unaffected ratio increased significantly. For peak power, work, sEMG
area, and joint rotation, the paretic/unaffected ratio increased from 55 to 85%,
56 to 72%, 68 to 91%, and 67 to 93%, respectively.
CG appears to be an effective
form of forced-use exercise eliciting more power and work from the paretic lower
limb muscles sustained by a greater neural drive. It also seems effective in
forcing a more symmetric power and work from the hip extensor muscles, but
neither from the knee nor the ankle.

Langue : ANGLAIS