Changes in the standing posture of stroke patients during rehabilitation

The aim of this study was to analyze the changes in the standing center of pressure (COP) in a hemiplegic adult population at the beginning and the end of in-patient rehabilitation. The trajectory of the COP was recorded on a force platform and was analyzed in terms of the frequency spectra of the center of gravity (COG), and the frequency spectra of the COP minus COG, a derived measure of neuromuscular stiffness. The study population consisted of eight hemiplegic subjects, median age of 53.5 years (range 27–79 years). The median interval between stroke and the first series of measures was 31 days (range 4–127) and the median interval between the two measures was 47.5 days (range 12–92). All the subjects were treated in an inpatient setting in a Neurorehabilitation Center. Our results showed that following rehabilitation, there was a reduction in the amplitude of the medio-lateral frequency spectra of the COP from a median of 5.651 mm (range 3.13–14.05) at the first measurement to 4.408 mm (range 2.40–8.58) at the second measurement. These changes were significant (p < 0.05). Significant changes were also observed in the measure of COP minus COG, from 1.324 mm (range 0.92–2.63) on the first measure to 0.917 mm (range 0.46–1.53) on the second measure. In conclusion, the medio-lateral COP trajectory of hemiplegic subjects significantly improved during rehabilitation. We hypothesized that a major component of this improvement was the decrease in neuromuscular stiffness of the adductor and abductor muscles of the hips.