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Vertebral Osteophyte. Is it related to mechanics?

osteophyte

The patterns of vertebral osteophytosis (or the growth of bony projections from vertebrae) is a common study among researchers. The actual cause of these bony outgrowth projections has been questioned over the years, with some pointing to the abnormal movement patterns of motion segments. Others have questioned this and believe the cause to be related to age and genetics. In a 2014 paper, researchers sought to answer: Is vertebral body osteophytosis a reliable indicator of occupational stress1. A shallow dive into their findings will be shared here.

What we do know from the work of Kumareson et al. 2 and Adams & Roughley 3 is that osteophytosis looks to be linked to degeneration of the intervertebral disc which is defined by an aberrant, cell-mediated response to progressive structural failure. With this structural failure, inevitably, there must be physical stress and thought to influence the cells at the vertebral-disc interface margins to produce bony outgrowths.

Furthermore, others have looked at these bony outgrowths and tried to relate them to aberrant mechanical loading patterns along with physical age and genetics. 4 5 6. Archeologists that study biological remains have used this finding as a tool to measure historical population activity level and lifestyles 7 drawing speculative conclusions on the inter and intra-population differences. Two well documented skeletal population differences demonstrated that the women had more severe osteophytosis than the men and was thought to be caused by heavy lifting that the men did not do during this same time period.

However, other researchers believe that degeneration is not solely related to physical activity and more so related to genetic factors 8, ageing 9, and body mass 10. And with this, one can see the complexities underpinning the causative factors of these bony outgrowths that some call ‘bony spurs’ projecting from vertebrae.

The osteophytes’ anatomical margins are the entheses, which you can see in our Lumbar Spinal Stenosis Model. This is the region where a muscle, tendon or ligament attaches to the bone. It is the interface where force intersects with bony anatomy. This is often represented in the extremities but the same biological process is thought to be at the crux of these anatomical changes.

osteophyte

Osteophyte Projection in our Lumbar Spinal Stenosis Model

What did these researchers investigate?

A group of researchers 1 wanted to see if they could determine whether mechanical factors related to osteophyte formation. They looked at these entheseal margins in the lower and upper extremities and the spine to see if they were correlated. Their logic was to see if the bony osteophytes were similar in all anatomical regions and if so, they could speculate that there was a mechanical influence of the formation of them. They also wanted to see if age played a factor as they explored the relationship between vertebral osteophyte formation and entheseal changes in the extremities.

The samples that were used came from a burial site in Cedynia, Poland. 101 male skeletons were examined and divided into two age groups, 20-40 years old and 41-56 years old. To determine the vertebral osteophyte degree, they used a rating scale developed by Swedborg (1974) to measure the entheseal grade; they used Mysezka & Piontek (2012). The entheseal anatomical sites they measured included the humerus, radius, femur and the tibia.

What they found

Interestingly, the researchers found no significant age differences when comparing the presence and degree of both osteophytosis and enthesopathy in the spine and extremities, respectively. They did find a significant correlation between the lower extremity enthesopathy and the vertebral osteophytosis, however. In other words, if they saw bony spurs in the lower extremities of the specimens, there was a good chance they were going to find vertebral osteophytes of the spine.

 

Does this solve anything regarding whether mechanics plays a role in osteophyte presence?

No. But it does shed light on the possible mechanics. These researchers agreed that other factors, besides physical ones, could be at play and should be considered. In particular, like age, body mass and genetics.

 

Commentary by Jerome Fryer

From a clinical standpoint, we should be mindful of these anatomical changes. Do they cause pain and problems all the time? No. We have seen this time and time again with clinically abnormal imaging findings. However, in the case of vertebral osteophytosis, a projecting osteophyte into the foramen where an exiting nerve root needs room for its vascular geometry for nourishing itself, space is everything. Learning about how to prevent the progressive changes of these types of osteophytes that can encroach on the dorsal root ganglia is important. Ongoing facet arthropathy is an adaptable process, but if adaptation is too great and osteogenesis takes up space where the nerve needs it, pain and disability can present and often, there is no turning back. My hunch is if we can improve the spine’s mechanics and keep an eye on disc height changes over a lifetime, we can keep the spine healthier and avoid spinal conditions like lumbar spinal stenosis. However, this is purely speculative in nature, and much more research on the causes of osteophytosis must occur. JF

 

  1. Anthropol. Anz. 71/4 (2014), pp. 381–389 Notes J. Biol. Clinic. Anthropol. Stuttgart, November 2014
  2. Kumaresan, S., Yoganandan, N., Pintar, F.A., Maiman, D.J. & Goel, V.K. (2001): Contribution of disc degeneration to osteophyte formation in the cervical spine: a biomechanical investigation. – Journal of Orthopaedic Research 19, 977–984. DOI: 10.1016/S0736-0266(01)00 010-9.
  3. Adams, M.A. & Roughley, P.J. (2006): What is intervertebral disc degeneration, and what causes it? – Spine 31, 2151–2161. DOI: 10.1097/01.brs.0000231761.73859.2c.
  4. Sambrook, P.N., McGregor, A.J. & Spector,T.D. (1999): Genetic influences on cervical and lumbar disc degeneration: magnetic resonance imaging study in twins. – Arthritis and Rheumatism. 42, 366–372. DOI: 10.1002/1529-0131(199902)42:2<366::AIDANR20>3.0.CO;2-6.
  5. Spector, T.D. & McGregor, A.J. (2004): Risk factors for osteoarthritis: genetics. Osteoarthritis and Cartilage 12, 39–44. DOI:org/10.1016/j.joca.2003.09.005.
  6. Knüsel, C., Göggel, S. & Lucy, D. (1997): Comparative degenerative joint disease of the vertebral column in the medieval monastic cemetery of the Gilbertine Priory of St. Andrew, Fishergate, York, England. – American Journal of Physical Anthropology 103, 481–495. DOI: 10.1002/(SICI)1096-8644(199708)103:4<481::AID-AJPA6>3.0.CO;2-Q.
  7. Novak, M. & ˇ Slaus, M. (2011): Vertebral pathologies in two Early Modern Period (16th–19th) century) populations from Croatia. – American Journal of Physical Anthropology 145, 270–281. DOI: 10.1002/ajpa.21491.
  8. Sambrook, P.N., McGregor, A.J. & Spector,T.D. (1999): Genetic influences on cervical and lumbar disc degeneration: magnetic resonance imaging study in twins. – Arthritis and Rheumatism. 42, 366–372. DOI: 10.1002/1529-0131(199902)42:2<366::AIDANR20> 3.0.CO;2-6. , ageing and body mass index.
  9. Snodgrass, J.J. (2004): Sex differences and ageing of the vertebral column. – Journal of Forensic Science 49 (3), 458–463.
  10. Oishi, Y., Shimizu, K., Katoh, T., Nakao, H., Yamaura, M., Furuko, T., Narusawa, K. & Nakamura, T. (2003): Lack of association between lumbar disk degeneration and osteophyte formation in elderly Japanese women with back pain. – Bone 32, 405–411. DOI:10.1016/S8756-3282(03)00031-0.
  11. Anthropol. Anz. 71/4 (2014), pp. 381–389 Notes J. Biol. Clinic. Anthropol. Stuttgart, November 2014
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