The last installment of this column addressed pain in the back of the thigh from hamstring muscle injuries.  Injuries from the low back, which produce pain in the back of the thighs were introduced.

Spinal nerve roots exit between each pair of vertebrae in the spine.  In some cases, the disc (shock absorber between the vertebrae) can become damaged and inflamed.  The inflammation is the most important factor in the pain.  The inflamed disc can cause back pain and if the inflammation carries over to the spinal nerve.  Once nerves are inflamed, they can display symptoms in the back and down its path such as pain, numbness, tingling, a “pins and needles” sensation, electric-like feelings and weakness in the muscles supplied by the given nerve.  The size of the protrusion or herniation of the disc is not as significant of a factor as was once believed. 

The low back is also called the lumbar spine.  There are five lumbar vertebrae and they are identified and numbered L1 through L5.  The lumbar spine joins the pelvis at its center bony section called the sacrum which is comprised of several naturally fused vertebrae.  The section that is most important for this discussion is the top section which is numbered S1.  The nerves are also numbered in a similar manner. 

The two lowest nerves in the low back, L5 and S1, can individually cause pain radiating down the back of the leg.  The distribution of this type of pain can vary somewhat in each individual case.  Some people have low back pain, gluteal pain, hamstring pain, calf pain and even foot pain.  Others can have back pain and hamstring pain only.  Some only have pain in the glute or in the back of the thigh. 

There are a few reasons that a trainee would have nerve-related pain in the hamstring region only.  The first reason is that there are several types of disc injuries and some do not cause back pain, rather they cause thigh and leg pain only.   A fragment of the disc can tear free from the disc itself and is known as a sequestered disc.  This commonly produces leg pain only. The second reason is a trainee could have narrowing of the space where the nerve exits the spine.  This is known as foraminal stenosis.  The foraminal stenosis can be caused by bone spurs in the foramen or a disc protrusion into this space (intraforaminal protrusion).   Lastly, there is a muscle under the gluteus maximus muscle (buttocks) which is called the piriformis.  The piriformis originates (attaches) on the outer edge (lateral) sacrum and inserts (attaches) to the top of the upper thigh bone (greater trochanter of the femur).  The L5 and S1 nerve roots join together and form the sciatic nerve.  The sciatic nerve passes behind the piriformis muscle.   We are not all anatomically identical, which is surprising to most patients.  About 1/3 of the population have the sciatic nerve pass through the piriformis muscle.  If the piriformis muscle becomes too tight, the sciatic nerve can become irritated and will produce pain in the back of the thigh.  The piriformis syndrome is less common than the foraminal stenosis or the sequestered disc.

Exercises that aggravate the hamstring muscles can often irritate the nerve related pain – stiff-legged deadlifts, Romanian deadlifts, cleans, good mornings, hypers.  These are all exercises that place a stretch on the nerve.  Usually any form of hamstring stretch will stretch the sciatic nerve or nerve roots and will make the symptoms worse.  This is a key point.  Most patients think they aren’t flexible enough and they have heard that stretching is important to reduce back pain.  So they perform hamstring stretches, especially with the foot pulled back (dorsiflexion) and this stretches the inflamed nerve even more causing more symptoms.  Inflamed nerves don’t respond well to stretch. 

If the pain does not resolve with conservative care (chiropractic, physical therapy, acupuncture, various medications or selective nerve blocks) a microsurgical procedure can be a very sound solution.  Robert S. Bray, Jr., MD is a neurosurgeon who is the Director of Diagnostic and Interventional Spinal Care (D.I.S.C.) in Marina Del Rey, CA.  Dr. Bray specializes in microsurgical techniques for the spine and has numerous patents of surgical equipment to advance microsurgery.  Dr. Bray is also involved in several FDA research projects to advance more conservative surgery on the spine.   Dr. Bray commented “It is not uncommon to hear a patient complain of hamstring pain that hasn’t resolved over four or five months time regardless of the treatment he/she has received.  A microsurgical procedure may be indicated based upon the extent of the neurologic deficit (muscle weakness from the inflamed, compressed nerve) or the severity of the patient’s pain.  The microsurgical techniques for a problem like this would entail a small incision, perhaps one inch in length, and the use of a powerful microscope to visualize the disc after we have moved aside the muscles.  The ligaments and bone are spared.  We can then remove a free disc fragment from the nerve or shave down a bone spur in the neural foramen and allow the nerve to recover.  The total blood loss is about one teaspoon.”

So, sometimes pain in the back of the thigh is not a hamstring strain.  Sometimes it is from the lower back.  If you have experienced pain in the back of your thighs and it doesn’t seem to improve you should see a neurosurgeon or orthopedic surgeon with spine specialty training or a chiropractor with sports medicine or orthopedic specialty training to derive a diagnosis.  Do not attempt to diagnose yourself.  Increased pain with the exercises described in this article or by stretching does not provide you with a diagnosis or appropriate treatment plan.