Abstract
Single-group, repeated measures study utilizing convenience sampling of healthy young subjects to determine if interspinous spacing changes with flexion or extension passive intervertebral movements utilizing real-time ultrasound (RTUS) and if so then by how much in the lower lumbar segments. Data was utilized from 50 total subjects (31 females and 19 males) with an average age of 25.90 ± 4.54 years between the ages of 18-45 were measured via Real-time Ultrasound and images were taken in side-lying 4 times. Digital measurements were taken from the peak of the spinous processes of L4-L5 and L5-S1. The distance of each segment was measured in millimeters in each position of neutral side-lying and follow a flexion/ extension PIVM. Descriptive statistics were used to summarize data and presented as mean ± SD. An independent sample t test was used to compare the mean age, and baseline (neutral) interspinous distance measurements between female and male subjects. P value was set at 0.05 and all of the comparisons were two-tailed. Repeated measures ANCOVAs on interspinous space between L4-5 and L5-S1 before-after the flexion and extension PIVMs were made by including covariates gender, height, and age. The measured interspinous distances between L4-L5 (F=128.58, df=1,48, p<0.001, ηp2=0.728. p<0.001) and L5-S1 (F=168.27, df=1,48, p<0.001, ηp2=0.778) were significantly higher following the flexion PIVM compared to neutral 1. The measured interspinous distances between L4-L5 (F=72.821, df=1,48, p<0.001, p<0.001, ηp2=0.603) and L5-S1 (F=113.358, df=1,48, p<0.001, ηp2=0.703) were significantly lower following the extension PIVM than neutral 2. Gender (F=0.878, df=4,44, p=0.485) and height (p=0.799) were not significantly associated with those above-mentioned changes. However, age was found to be significantly related to L4-L5 flexion (F=7.38, df=1,47, p=0.009, ηp2=0.136). The direction of relation between age and L4-L5 flexion (β=0.351, t= 2.60, p=0.013, p=0.013) was positive and linear. After controlling for age, there were significant changes in L5-S1 flexion (F=6.168, df=1,47, p=0.017, ηp2=0.116) and extension (F=8.321, df=1,47, p=0.006, ηp2=0.150). During a flexion and extension PIVM there were statistically significant changes in interspinous movement regardless of the subjects’ gender and height, and age. These findings validate the changes in interspinous distance during a lumbar PIVM technique through objective imaging with RTUS and provide baseline data for future research to identify if lower spinal dysfunctions will ultimately result in any changes to the resting position of interspinous spaces and during flexion or extension PIVMs.