I am posting full article--hopefully.

SPINE
Posted on the ORTHOSuperSite October 12, 2010

Study explores natural history of lumbar ligamentum flavum thickening
Submit a Comment Print E-mail

ORLANDO, Fla. — Researchers at Rush University Medical Center in Chicago have identified important changes in the ligamentum flavum in individuals aged 20 to 60 years-old, which may exacerbate back pain in the later decades of life.
Their findings, presented here at the 2010 Annual Meeting of the North American Spine Society by Howard S. An, MD, included identifying a correlation between a thickened ligamentum flavum and amount of disc degeneration based on MRI images.
An credited Justin J. Munns, MD, with heading the National Institutes of Health-supported study into ligamentum flavum (LF) thickening.
ADVERTISEMENT




Howard S. An
“LF thickness increases with age and with level except at level L5-S1,” An said, summing up the results. Furthermore, LF thickness correlates with lateral recess stenosis and low back pain (LBP) symptoms, he said.
An and colleagues enrolled 83 volunteers, aged 20 to 60 years, in their study. They obtained high-resolution images from a 1.5T MRI unit of each volunteer’s spine and then enhanced the images using special software to provide added details about the lumbar LF, such as its lateral, medial and mean thickness, and length.
When the researchers compared those characteristics to the volunteers’ age, gender, lumbar disc height, LBP, facet joint width and disc grade on MRI with the Phirrmann scale, they found LF thickness gradually increased from L1 to L5, decreasing notably at L5-S1.
There were no differences between the left and right side LF thickness, however, An said, “Males have thicker LF than females as may be expected. It was interesting to note LF thickness increased with age even from the second to third, and third to fourth decade, and so forth.” He noted studies like this need to be done with volunteers aged up to 80 or 90 years to see whether these trends continue later in life.
Reference:
Munns JJ, An HS, Espinoza Ori’as AA, et al. Ligamentum flavum hypertrophy related to disc degeneration. Paper #165. Presented at the 2010 Annual Meeting of the North American Spine Society. Oct. 5-9, 2010. Orlando, Fla.

We’ve always been taught that the ligamentum flavum is elastic tissue and I believe this is true. I’m not convinced that this is hypertrophy. I’m convinced that indeed it is some kind of an elastic tissue that when the disc collapses it becomes redundant in itself, so when you go in and you distract it anteriorly and create a long arm motion segment, you get your indirect decompression because you’re moving everything out.
I think this is not hypertrophy; it is more of a shortening.
— Courtney W. Brown, MD
Denver, Colo.