Goal of the Study?
In this study 1, the authors investigated the flexion-extension range of motion (ROM) and centre of rotation (COR) of lumbar motion segments in a large population, as well as the relationship between lumbar movement and sex, age and intervertebral disc degeneration (IVD).
Why are they doing this study?
Research on the in vivo motion of the spine has a long history. However, many of these studies have used non-invasive technologies with inherent limitations impacting their accuracy and precision. Moreover, many studies have included a lower number of subjects, preventing the ability of the data to represent the general population.
The authors argue that radiographic techniques in this study help overcome these limitations as the images allow for better visualization of each vertebra and movement of the lumbar segments. Additionally, the use of a large sample size for this study addresses the issue of representation and is the largest study to date looking at in vivo lumbar motion.
What was done?
The researchers did a retrospective study looking at the radiographs of the lumbar spine in full flexion and extension for 602 patients, with the age and sex documented for each one. Additionally, they used MRI scans of 354 patients.
All spinal levels between T12-L1 and L5 – S1 were analyzed, resulting in 3612 lumbar motion segments from the radiographic images. They also examined 2124 images from the MRI scans looking at disc degeneration. ROM and COR were calculated for all lumbosacral segments using the software. They then examined the associations between motion and age, sex, spinal level and disc degeneration.
What did they find?
The median ROM in this study was 6.6 °. The researchers found an association between age and ROM, with older individuals, have lower ROMS. They argue these findings clearly demonstrate a relationship between age and lumbar spine flexibility independent of any signs of spinal degeneration. They also found that lower ROMS were associated with disc degeneration. However, they did not find any association between sex and ROM.
In this study, they did not find an association between the position of the COR and the spinal segment. The most common COR was at the centre of the lower endplate of the IVD or slightly lower. With degeneration, particularly severe degeneration, they found the location of the COR spread randomly around the centre of the intervertebral space.
One of the main limitations of this study was the sole focus on the flexion-extension motion of the lumbar spine rather than including information on movements of different areas of the back.
Why do these findings matter?
This study comprises the largest examination of the in vivo lumbar spine in flexion-extension, paying attention to age and spinal degeneration issues. Understanding the relationship between age and spinal mobility provides patients and doctors with information to better treat back pain and instability.