Abstract
Purpose
Posterior pelvis tilt (PPT) would affect lumbar lordosis and lead to hip flexion, which causes difficulties walking and standing in patients with hip disorders. Hip flexion movement associated with PPT is well known. We investigated the effect of the angle of hip flexion without the movement of PPT in the supine position.
Methods
The study enrolled 24 healthy males with an average age of 20.5 ± 2.3 years. Two pelvic positions in the supine position were investigated: (1) the limited position of the PPT by 500ml PET bottle with water placed under their low back, and (2) the position without placing a PET bottle. We assessed unilateral hip flexion angle with photos taken with a digital camera. For reference, we took an X-ray of a healthy female and observed the lumbo-sacral from the sagittal plane in the supine position.
Analysis
Data was processed by Image analysis software (Image J 1.42, NIH). Paired t-tests were used to assess the range of motion of individual joints in each position in the sagittal plane. MEPHAS software (Oosaka University. Japan) was used for all statistical processing, and the level of significance was set at P < 0.05. In addition, we also measured the lumbo-sacral angle (LSA), the lumbo-lordotic angle (LLA) and the sacral slope angle (SSA) with the X-ray.
Results
The angle of hip flexion decreased 22.9±6.04 degrees on average in the limited position with a PET bottle compared with the position without a bottle (P<0.01). The angle of pelvis decreased 4.8±2.0 degrees on average.
Discussion
The angle of hip flexion significantly decreased in the limited position with a PET bottle. Our results suggest the association movement of the PPT with hip flexion movement in the supine position. This suggests that movements of the LLA and SSA are involved greatly in hip flexion.
Significance of study
Our results provide evidence that could lead to more effective way of measurement of the primary hip joint (coxal femoral joint) flexion in the supine position for the patients with hip diseases. If we can measure primary hip joint (coxal femoral joint) flexion, it may also be measured mobility of the pelvis. Measurement of the hip joint flexion should consider the movement of the lumbar vertebrae and the sacral slope.
