The Role of the Lumbar Spine in Recurrent 'Hamstring' Problems

John Orchard is a sports physician and sports injury researcher based in Sydney, Australia. He is a Conjoint Senior Lecturer at the University of New South Wales and a Senior Fellow at the University of Melbourne. Dr Orchard is Medical Director for the Sydney Roosters Rugby League Football Club. He is Injury Survey Co-ordinator for Cricket Australia and the Australian Football League, and is a board member of the New South Wales Sporting Injuries Committee.

Dr Orchard is also an editorial Board Member for The British Journal of Sports Medicine and is Clinical Assistant Editor of The Journal of Science and Medicine in Sport. Dr Orchard disseminates his work and keeps the public informed on topical sports injury subjects at www.injuryupdate.com.au - Australia's premier sports injury website.

Dr Orchard's recent work has focussed on the role of lumbar spine problems which lead to symptoms in the hamstring muscle group. This type of problem is relatively common in athletes, particularly older athletes and it is often the underlying cause in those patients who suffer from recurrent 'hamstring' problems. We caught up with him recently to get an insight on this frustrating problem.

Although Sciatica due to a disc prolapse is a well established cause of lumbar spine pathology leading to buttock, posterior thigh and calf pain, what is the proposed mechanism of more subtle lumbar spine problems which cause symptoms in the hamstrings?

"It is a very tortured pathway for the L5 nerve root to make it from the spinal canal to join the lumbosacral plexus (network of nerves in the lower back and pelvis) and there are a number of ways that subtle compression to the nerve may occur. Disc prolapses at L4/L5 and/or L5/S1 are the most likely mechanism, but compression by a structure called the lumbosacral ligament in the lumbosacral canal (a centimetre or two further down the spine to where a disc prolapse would affect the nerve root) may also be a common mechanism of subtle nerve entrapment.

Illustration: anatomy of a disc prolapse

So is there any actual damage to the hamstring muscle in these patients?

"We believe that subtle L5 nerve entrapment leads to both an increase in risk for Magnetic Resonance Imaging (MRI)-positive hamstring strain and an increase in MRI-negative hamstring symptoms, so the answer is both that a traditional muscle strain can occur, but sometimes hamstring symptoms might be present with no strain.

What is the research evidence on this type of injury?

"We don’t have a lot of good direct evidence, but some strong indirect evidence. Muscle strains in the hamstring and calf groups are far more common in older athletes, whereas there is no age relationship for quadriceps and groin muscle strains. If the age-related predisposition for hamstring and calf injuries was just related to local muscle aging, it should equally affect the quadriceps and groin muscles. We also know that after a few years of playing intense sport, L4/L5 and L5/S1 (the nerve supply the posterior thigh region) disc degeneration is extremely common, whereas disc changes at the upper lumbar levels (L1, L2 and L3 – the nerve supply for the front of the hip and groin) are far less common.

"The additional piece of indirect evidence is that there are cadaver studies showing common hypertrophy of the lumbosacral ligament in those cadavers with significant degenerative changes. It is a nice theory (which is basically an expansion on what physios have been saying for years) but hard to prove in vivo. This area is tiger country anatomically and rarely seen by surgeons in live people because it is relatively inaccessible.

What are the most effective investigations for helping to diagnose this type of injury?

"It is a diagnosis generally made by weight of symptoms, such as recurrent hamstring and calf pain, along with symptoms of low back and/or hamstring and calf 'tightness'. We think an athlete who sustains what appears to be a hamstring strain but which is MRI-negative is more likely to have subtle nerve impingement. It is worth imaging the lumbar spine and usually very easy to see a 'tight' vertebral canal (spinal stenosis) and also a prominent lumbosacral ligament on a T1-axial view of an MRI scan. However, this appearance is almost universally present in older football players and fast bowlers, for example, just as some L5/S1 disc space height loss is also almost the norm in this population.

What treatment options are available for this hamstring pain that is originating from a problem in the lower back?

"I am far more inclined to prescribe anti-inflammatories for an athlete with an MRI-negative (or very low-grade) muscle strain than a high-grade strain. Anti-inflammatories are likely to reduce soft tissue mass but don’t affect nerves, so they are helpful in relieving nerve impingement. It is even better to use a guided cortisone injection to get the anti-inflammatory effect closer to where you want it, but this requires imaging control and is therefore semi-invasive.

Because anti-inflammatories reduce scarring and healing, in a more traditional muscle strain without a nerve-component, I tend to avoid them. It makes sense to suggest that slump stretching and other forms of ‘neural mobilisation’ may help with nerve impingement, so I would recommend trying this and continuing if it doesn’t lead to an increase in symptoms. Hamstring strengthening is also worthwhile for prevention."

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