SIB# 398- Spinal Alignment Determines Motion
The Study: Spinal kyphotic alignment changes spinal movement strategy during lateral reaching motion while in a sitting position.
The Facts:
a. This study was done in Japan and the authors note that the population aged over 65 is increasing in Japan.
b. They indicate that the most common postural change in the population of ageing patients is thoracic hyperkyphosis and noted that increased kyphosis may create difficulty for patients when reaching from a seated position.
d. The authors wished to determine the effect of increased thoracic kyphosis on spinal movement when reaching while in a seated position.
e. They used 19 healthy males with an average age of 26.5 years.
f. Each subject was seated and then asked to reach to the right with their right hand and arm with the spine in their normal position and then with the thoracic spine in a flexed (kyphotic) position. (Note: The level of the point they reached to was at shoulder level.)
g. To ensure subjects remained in the hyperkyphotic position, subjects were placed in a trunk brace that caused spinal flexion..
h. The authors then measured spinal angular movement at levels T1, T4, T8, L1 and L5 during the reaching motion using a 3D system which incorporated 10 infrared cameras and four force plates.
i. They found no significant difference between the two groups in the movement on the x-axis meaning that placement of the subjects in the two test positions did not result in differing postures in the frontal plane.
Below is a summary of the changes in motion which were noted:
j. When reaching from the normal posture, T4 rotated more freely to the right (Ipsilateral Y axis rotation) in the normal position than when the spine was in the flexed position.
k. When reaching from the normal posture, T8 tilted significantly more to the left (Contralateral Z axis rotation) than when the spine was in the flexed position.
l. When reaching from the normal posture, L1 rotated to the left (contralateral Y axis rotation) and to the right (ipsilateral Y axis rotation) when the spine was in the kyphotic position!*
(Note that this is a completely opposite coupling motion simply by altering the starting posture for the movement. Ed.)
m. Interestingly, L5 left side rotation (Y axis contralateral rotation) was significantly more pronounced when reaching from the kypotic position than it was in the normal posture.
(Also interesting that L5 rotation was significantly increased when reaching from the hyperkyphotic position. Definitely needs more study, but might this be connected to the fact that lower lumbar disc injuries occur so frequently when forward flexion is combined with a tilt and/or rotation of the thorax? Ed. )
n. They also note that more research is needed in this area.
Take Home:
Changes in spinal posture (thoracic flexion) in the seated position affected spinal motion during reaching motions. .
Reviewer's Comments:
This study shows that vertebral movements during normal positioning are significantly affected by alteration in posture, in this case increased thoracic kyphosis. The concept that motion is affected by spinal alignment is an important one for all chiropractors to understand. This study illustrates the importance of global spinal alignment as a foundation of spinal movement. It is worth a read, even for those doctors who have traditionally concerned themselves more with rehabilitation of vertebral motion than restoring spinal posture.
Reviewer: Roger Coleman DC
Editor’s Comments: The importance of spinal posture as a determinant of spinal function is illustrated in section l above (italics and emphasis mine), where the coupled motion, in this case Y axis rotation, was completely reversed simply by altering the starting posture for the motion. This is just one example of why all chiropractors, particularly those who utilize motion palpation to evaluate their patients, need to be keenly aware of the patient’s global posture. That abnormal motion or restriction restriction you feel may be entirely normal IF the patient’s sagittal plane postures are significantly altered. There’s much more work to be done on this subject but certainly an area our colleges need to be seriously working on. This was an interesting paper. Too bad this good work is being done by the PTs.
Editor: Mark R. Payne DC
Reference: Morikawa T, KatohH. Spinal kyphotic alignment changes spinal movement strategy during later reaching motion while in a sitting position. J Phys Ther Sci. 2020 Jan;32(1):48-51. doi: 10.1589/jpts.32.48. Epub 2020 Jan 22.
Link to Abstract: https://www.ncbi.nlm.nih.gov/pubmed/32082028
Link to Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7008015/pdf/jpts-32-048.pdf