Variability of forward trunk bending angle at standing posture in people with Parkinson’s Disease using the video measurement.

The purpose of this study was to clarify whether the angle of anterior trunk flexion at standing posture changes over a 30 second period.

People with PD who could stand for longer than 30 seconds were recruited. The participants were instructed to keep standing as they feel comfortable and the flexion angle while standing for 30 seconds was recorded on video. The flexion angle is calculated as follows: angle defined between a line drawn from the seventh cervical (C7) to the fifth lumbar (L5) spinous processes and another line from the L5 spinous processes to the lateral malleolus of the foot. According to the flexion angle at the start of the measurement period people with PD were classified into three groups: normal, anterior trunk flexion, and camptocormia. We investigated whether the flexion angle improved or worsened and whether there were converters in the classification of stooped posture at the end of the measurement compared to the start. Additionally, the video measurement data was analyzed by two-dimensional motion capture analysis. The primary outcome measure was the standard deviation of the mean flexion angle in the video measurement. For statistical analysis, Kruskal-Wallis test was performed across the three groups.

Thirty-two people with PD were included in this study, including 15 people with normal posture, 7 people with anterior trunk flexion, and 10 people with camptocormia. The flexion angle of twenty-nine people (90%) worsened from beginning measurement to end of 30 second period, while the flexion angle of three people improved. There were six converters (18%) in the classification of stooped posture (three converted from normal to anterior trunk flexion, two converted from anterior trunk flexion to camptocormia and one from anterior trunk flexion to normal). The standard deviation of the mean flexion angle in camptocormia group was significantly higher rather than the other two groups, while there was no significant difference between the other two groups (0.5 vs 0.7 vs 2.0). 

This study suggests that most people with PD show worsening stooped posture when they maintain an upright position for 30 seconds. Particularly, camptocormia group has a larger variability of flexion angle.

Improving stooped posture is one of the important needs for people with PD. It is necessary to consider using video rather than a photograph for precise evaluation and classification of stooped posture.