Back pain will affect up to 80% of the people in this country at some point in their lifetime, with 20% to 30% of the population experiencing back pain at any given time. The prevalence of BP peaks between the ages of 35 and 60 years. Of the people who develop acute BP, only about 4% develop chronic BP, with about one-third of those permanently disables due to their pain. People with BP use more health services than people with other disabilities, and BP is the second most common reason patients seek medical care. Estimation of annual costs in the U.S., when lost productivity, lost work time, diagnosis treatments, litigation and disability are factored in, is up to $100 billion.
Patients with low back pain may have poor posture or what is known as postural asymmetry. Normal, or good, posture is non-fatiguing, effortless and painless, and requires the least expenditure of energy. With good posture, a person avoids sustained contraction of muscles needed for balance.
Postural asymmetry may also be defined as an imbalance of one part of the body that is compensated for by a malalignment or imbalance of another part or segment of the body. With such a malalignment excessive tension in certain muscle groups may occur that can lead to abnormal stresses on joints, ligaments, and the discs in the back. Postural asymmetry may produce an excessive amount of tension and tightness in postural (antigravity) muscles, such as hamstrings and back extensors, and less tension in non-postural muscles such as the abdominals and glutei. The asymmetries may vary depending on whether a person is standing, sitting, or lying down.
Postural asymmetry may be related to structural or functional causes. Structural causes include an actual shortening of bone between the ankle and the hip or a pelvis that is larger on one side versus the other. Functional causes include poor footwear, flat feet (pes planovalgus), muscle imbalance generated by tightness or weakness and shortening or relaxation of the ligament. These structural and functional causes can produce an unbalanced pelvis (pelvic obliquity) and/or make one leg longer than the other (a leg length discrepancy, LLD). Poor work habits may also contribute to postural asymmetries.
Pelvic obliquity or LLD impose strain because the body attempts to compensate for the distortion in posture with a functional scoliosis or abnormal curvature of the spine, to maintain balance of the head and shoulders over the feet. This may result in the spine being skewed or rotated.
Investigators have found that the prevalence of LLD in patients with chronic low back pain is greater than in those without pain. In another study that evaluated the amount of pelvic obliquity in patients with and without chronic LBP, there was no significant difference between those two groups. Pelvic obliquity and LLD may not cause back pain, but they may aggravate or perpetuate symptoms after a traumatic event.
Typical characteristics of the low back pain associated with pelvic obliquity and LLD have been described as gradual in onset, typically beginning the late adolescence or early adulthood, chronic or recurrent, and precipitated by trauma or strain, such as lifting. The pain may begin within 20 to 30 minutes of standing and be promptly relieved on sitting.
The feet are the foundation of an upright posture and should not be overlooked when evaluating back pain. Careful evaluation of the feet as well as leg lengths and alignment of the pelvis should be an integral part of any back evaluation. Sometimes postural training and use of a shoe lift or arch support may be all that is needed to alleviate long standing back pain.
– by Dr. Robert C. Martin