The lumbosacral ligament

[hhh]

I've read a bit where authors have waxed lyrically about hamstring injuries in the AFL being the result of entrapment by the lumbosacral ligament rah-rah-rah. Stumbled upon this article. Would be interested in your comments, particularly as this age group is matched for age for an AFL population. And even if this is the mechanism how are you meant to treat the problem anyway?

Cells Tissues Organs. 2000;166(4):373-7.
Related Articles, Links
http://www.ncbi.nlm.nih.gov/entrez/utils/lofref.fcgi?PrId=3030&uid=10867439&db=pubmed&url=http://content.karger.com/produktedb/produkte.asp?typ=fulltext&file=cto66373
The lumbosacral ligament. An autopsy study of young black and white people.

Hanson P, Sorensen H.

Department of Medical Anatomy C, Laboratory for Functional Anatomy and Biomechanics, The Panum Institute, University of Copenhagen, Denmark.

The lumbosacral ligament (LSL), situated between the L5-vertebra and the sacrum, was studied in autopsy material. Twenty-eight cadaveric specimens from 12 black and 16 white persons aged 17-30 years were studied during routine forensic autopsies. The ligaments were measured and determined in situ. Thereafter, the ligaments were removed for histologic preparation. The ligament in the black subjects was thicker compared with the white (7.5 +/- 1.4 vs. 5.7 +/- 1.2 mm), and wider (11.7 +/- 1.6 mm in the black vs. 9.2 +/- 0.5 mm in the white), yielding a greater cross-sectional area in the black group (70.7 +/- 22.8 vs. 34.5 +/- 11.4 mm(2), p < 0.001). However, no histological differences were noted. The previously described fibro-osseus tunnel could not be detected in any of the subjects. In all instances, the ligament was situated medial to the L5 nerve. Compression of the L5 nerve under the previously presented fibro-osseus tunnel could not be confirmed

[sydunisportsmed]

Yikes!,

Just downloaded the paper from the Sydney Uni library and it is a good one that I was unaware of when publishing this paper:



http://www.injuryupdate.com.au/images/research/BJSML5nerve.pdf

This Hanson paper is adamant that the lumbosacral ligament was present in ALL young subjects but that it passed MEDIAL to the L5 nerve root so could not entrap it. Previous study has suggested that the L/S lig was often absent in young people but developed in response to degenerative changes in the lumbar spine and passed LATERAL to the L5 nerve root and therefore could entrap it.

In cases where the nerve gets entrapped, there may actually be 2 L/S ligaments on either side of the nerve. And I agree that this Hanson paper casts doubt about how common this would be in younger people. A great pity this paper wasn't referenced in the BJSM study.

It also calls into question whether the marked structure in Figure 2 of the BJSM paper is actually the L/S ligament. It seems to be present in some imaged lumbar spines and not other, and we presumed it was the ligament as described by Nathan, Briggs etc. However, Hanson is saying that the L/S ligament is medial to L5 nerve, which is definiely not the case in figure 2.

I would still maintain that the general theory that there must be a proximal degenerative component that predisposes to hamstring and calf injuries in older athletes and footballers is a strong theory.

We don't have the smoking gun yet though, and this Hanson paper tips cold water on the L/S ligament being the culprit (unless it has two branches on either side of the L5 nerve when you get older!).

Send me an email if you don't have .pdf of the Hanson paper and I'll pass it on.

[hhh]

If you had have been aware of this paper I doubt the article proclaiming a mechanism for injury would have made it to BJSM!! It is a 2000 paper, how did it slip through the lit review or through the review process?

[sydunisportsmed]

Well you can't sack the reviewers because they don't get paid anyway! The peer review process is far from perfect, and no one was doing a PhD thesis on the lumbosacral ligament amongst our authors so we didn't have the Hanson paper. There are about 200 hits on pubmed for lumbosacral ligament so it would take 6 months to review them all.

The major points are:
Hanson and the other authors who are all describing lumbosacral ligament MUST really be talking about different structures. In the multiple other studies that describe L/S ligament anatomy, it passes over and lateral to L5 nerve root, e.g.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=2028306&query_hl=2

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=7166449&query_hl=2

So a more pertinent question may be how the Hanson paper got through the reviewers with the observation that the LSL passes MEDIAL to L5 nerve root, without mentioning that this is in contradiction to virtually all of the other authors who have written on this topic.

However, in defence of Hanson, the rest of the literature is based on general cadaver dissections (e.g. aged adults for the most part) whereas Hanson got young adults. Might be that what the Nathan and other papers describe as LSL is absent in many young adults and develops as a degenerative structure as you age. There could be a deeper LSL that is deep to the nerve root. I don't see how a ligament that is deep to the nerve can suddenly grow over it, so I presume the authors are talking about different structures.

The final question, which we don't know the answer to:
Does the peri-30 year old professional footballer with 100,000 Ks on the clock (e.g. Nathan Buckley) have a youthful L/S lig structure with no entrapment of L5 nerve, or possibly the older structure, where there is a branch of the ligament that could compress the nerve?

As I said there is enough in the BJSM paper theory suggesting that something is happening in this territory, but we still don't know much about the anatomy. It is still pretty much a no go area for the surgeons.

WRT treatment, guided cortisone injections to the nerve root, which can be done, are very helpful in a clinical setting.

[injuryupdate]

Interesting alternate anatomical explanation in the latest July 2005 supplement of Neurosurgery:

Anatomic Analysis of the Transforaminal Ligament in the Lumbar Intervertebral Foramen
[Anatomic Reports]
Min, Jun-Hong M.D.; Kang, Shin-Hyuk M.D.; Lee, Jang-Bo M.D.; Cho, Tai-Hyoung M.D.; Suh, Jung-Guen M.D.

Department of Neurosurgery, College of Medicine, Korea University, Seoul, Korea (Min, Kang, Lee, Cho, Suh)
Reprint requests: Tai-Hyoung Cho, M.D.,Department of Neurosurgery, College of Medicine, Korea University, 126-1, 5 Ga, Anam-dong, Sungbuk-ku, Seoul 136-705, Korea. Email: choth2@unitel.co.kr
Received, September 8, 2004.
Accepted, February 10, 2005.
Abstract
OBJECTIVE: The objective of this study was to evaluate the clinical significance of the transforaminal ligaments (TFLs) in relation to the area of the lumbar intervertebral foramen (IVF) by analyzing cadaveric spines.

METHODS: One hundred ninety-eight cadaveric lumbar IVFs were studied, and the existence and type of TFLs were identified. All IVFs were photographed, and the images were saved. The areas of the IVFs and TFLs were measured with the Scion Image for Windows image analysis program.

RESULTS: TFLs were found in 82.8% of the IVFs. The oblique inferior transforaminal ligament was the most common. The mean area of the IVFs was 155.8 ± 51.1 mm2, and the mean area occupied by the TFLs was 46.3 ± 37.6 mm2. The mean percentage of the IVF area occupied by the TFLs was 28.5 ± 18.8%.

CONCLUSION: TFLs are common structures in the IVF and may reduce the space available for the spinal nerve root within the IVF. In this circumstance, any compromise of the IVF may impinge on the nerve root.

[hhh]

I still think you are clutching at straws on this one. For one I don't think you can ever prove it and secondly it is too simplistic. No doubt degenerative lumbar changes contribute to injury, but the proposed mechanism is only one of many hypothesis that could be discussed with regards to lumbosacral degeneration

[injuryupdate]

There needs to be an anatomical explanation (and not just psychological) as to why:

(1) disc bulge of mild-moderate size in person A is asymptomatic but in person B doing same activities causes radicular pain.
(2) typical 30-year-old's back in player A has no apparent consequences but in player B seems to be associated with endless predisposition to calf and hamstring strains and Achilles tendinopathy.

Whether lumbosacral ligament is to blame is very arguable, but it seems to be the most described anatomical variation in this area (other than disc abnormalities themselves).

Although you can't write it up scientifically any more since no one likes publishing an uncontrolled case series, the clinical results for guided cortisone around the L5 nerve root as it exits the foramen are excellent in the scenario of chronic hamstring and/or calf pain.