A healthy human spine has three curves that ensure proper balancing of weight and shock absorption. The lumbar spine in the lower back naturally curves inward; this type of curve is called lordosis. The thoracic spine in the mid-back connects to the ribcage and curves outward, which is called kyphosis. Finally, the cervical spine in the neck is naturally lordotic.
Some people with lower back pain may find that they suffer from what is called flatback syndrome. This is characterized by the loss of normal curvature in the spine and usually manifests in the lumbar region. As the lumbar spine loses its curve, a number of mechanical changes occur in the body. Spinal discs, which act as shock absorbers between vertebrae, are subjected to uneven pressure. The muscles, tendons and ligaments throughout the back are pulled and lengthened; a muscle’s natural response to being pulled is to pull back in order to prevent being torn, and this extra work further strains the muscles. Pelvic position changes as well. The sacrum and coccyx together form a hook-shaped bone series at the very base of the spine which connects to the hip bones. As the lumbar spine becomes elongated, this hook is pushed down and under, putting the pelvis into what is called posterior pelvic tilt.
Not all instances of posterior pelvic tilt are instances of flatback syndrome. The two are interchangeable only if the pelvic position is accompanied by near-total loss of lordosis.
An obvious symptom of flatback syndrome is flatness of the spine.
In most people with flatback syndrome, the straightening of the lumbar spine causes the thoracic and cervical segments to pitch forward. One of the main symptoms of the condition is feeling like you might fall forward. As the condition progresses, you may require a cane or walker for balance.
People with flatback syndrome often have muscular pain in the back and pelvis.
Disc problems like bulging and herniation are a common result of prolonged flatback.
The most discussed cause of flatback syndrome is hardware implanted in the spine during surgery to correct scoliosis. Harrington rods used to be inserted into the spine to correct sideways curvature, but over time these devices tended to cause the spine to straighten out on the saggital plane as well.
Another, less commonly discussed cause of flatback begins below the back. Muscle imbalances in the lower body can pull the pelvis down and under, flattening out the lumbar lordosis from the bottom. One muscle imbalance scenario that may cause posterior pelvic tilt is tight hamstrings, glutes and lower abdominal muscles coupled with weak quadriceps, psoas and lower back muscles. Tight muscles exert a pull on body structures that is not balanced by the pull of weak muscles. The pelvis is pulled downward by the glutes and hamstrings and under by the lower abdominals.
Flatback syndrome may also be associated with other health conditions, such as arthritis and vertebral compression fractures common among people with osteoporosis.
The only real way to correct loss of curvature caused by scoliosis surgery is to re-operate, which entails breaking the original fusion, removing the devices that caused flatback and re-setting the fusion with newer techniques.
To correct flatback caused by muscle imbalances, tight muscles must be forced to regain elasticity and weak ones must be developed. For imbalances severe enough to cause flatback, simple stretching will not be enough to lengthen tight muscles. A technique called self-myofascial release (SMR) can be used to regain elasticity and reduce the pull these muscles are exerting on your spine. You can see videos of SMR for different muscles at http://www.myweightlifting.com/self-myofascial-release.html.
Once flexibility has been restored, you can begin a stretching routine to maintain it. You can also start building your weaker muscle groups. If you can, work with a physical therapist to ensure your form is correct and you are not causing harm.
It is important to understand that the lumbar curve is essential to the health of your back. If you suspect that your spine doesn’t curve naturally, consider the possibility that muscle imbalance is causing your lower back pain.