Low back pain is a very common condition and ranks second only to upper respiratory infection. According to the public data, approximately 80% of adult population will experience at least one episode of low back pain. The source of the pain is usually related to musculoskeletal components of the spinal column. The pain is originated from soft tissue structures, paraspinal musculature, ligaments, facet joints, bone structures, intervertebral discs and nerves.
The most common origin of the acute low back pain is from the soft tissue structures. Muscle strain and ligament sprain can result from overuse and produce severe pain with restriction of mobility. The pain is usually self-limiting and improves with conservative and nonoperative care within the first 6 weeks.
Sometimes acute low back pain becomes chronic with frequent flares. Among the causes for the chronic pain is radiculopathy which is generally associated with mechanical low back pain. The true radicular pain is the pain with a sensation of numbness and tingling traveling below the buttock area down to the upper or lower leg area.
One of the other causes for the chronic intermittent low back pain is an aggravation of lumbar spondylosis (arthritis of the spine). Exacerbation of nonradicular low back pain is usually frequent and associated with overuse or minor injury to the arthritic lumbar facet joints (main joints of the spine).
Low back pain can also be discogenic (related to the intervertebral disc pathology) in etiology. The presentation of the pain has symptoms that overlap with the pain produced by lumbar facet joints pathology. The discogenic pain is usually more intense and severe, also producing more significant restriction in mobility.
There are other causes for the low back pain that include infection, tmalignancy, spinal stenosis and specific musculoskeletal pathology.
Lumbar spinal stenosis produces leg pain and fatigue with ambulation which called neurogenic claudication. This pain occurs most commonly in older patients who complain of severe leg pain becoming intolerable after ambulating varying distances. The pain is a generally relieved after sitting or leaning forward while flexing the lumbar spine.
Vascular claudication pain caused by arterial insufficiency of the lower extremity. This condition can produce severe leg pain with ambulation, however, often relieved by stopping and standing. Also, patients can have leg pain at night which requires sitting and dangling the legs at the bedside. The risk factors for vascular claudication are tobacco smoking, diabetes, hypertension, and vascular disease.
Radicular leg pain and feeling of numbness and tingling is caused by irritation of the lumbar sacral nerve roots. Acute onset of the radicular pain could be a result of a disc herniation in young adults. Patients can describe subjective weakness and sciatica pain as a pain with numbness and tingling traveling from the low back and buttock into the thigh, calf and foot. Patients report that sitting is more bothersome than standing or walking.
Coccydynia is localized pain in the coccyx area that is usually chronic and severe. The pain is aggravated after prolonged sitting on firm surfaces. Radiation of the pain is not present but the pain can travel to the buttock or ischial tuberosity with both sides possibly involved.
Piriformis syndrome represents the pain originated from inflamed piriformis muscle with also sciatica nerve pain after sciatic nerve been directly compressed by the piriformis muscle. Patients report buttock and leg pain with numbness and tingling that is exacerbated after prolonged sitting. Patients also report localized buttock tenderness with palpation in the piriformis muscle area.
Sacroiliac joint dysfunction or sacroiliitis
Sacroiliac joint is an L-shaped articulation between the sacrum and the ileum. The joint pain usually is related to hyper or hypo-mobility for the joint, repetitive overloads, trauma and injury to the capsule of the joint. The pain can be instant or gradual in the low back area, buttock, leg or groin area with tenderness over the joint. Patients report abnormal sacroiliac joint motion patterns and increased discomfort with changing positions. The pain also involves associated muscles such as quadratus lumborum, erector spinae and piriformis muscles.
Hip pain caused by arthritis, osteonecrosis, infection or labral (joint capsule) pathology is generally localized to the groin and anterior thigh area. Pain is worse with weightbearing, climbing steps, or squatting to seat at a lower level. He pain is associated with antalgic gait and painful limited range of motion of the hip joint.
Chronic low back pain
Chronic low back pain without radicular component is commonly caused by degenerative conditions. The evolution of spondylosis or arthritis usually begins in the third decade of life and progresses with aging. The degenerative processes start with the intervertebral disc dehydration and subsequent loss of the disc height. The collapse of the disc space promotes osteophyte formation in the parallel of facet arthritis and ligamentum flavum hypertrophy and cause spinal stenosis.
Facet syndrome is associated with low back pain caused by inflammation of facet joints with resultant discrete pain associated with radiation into the buttock area. This pain could travel further down to the posterior thigh on the affected side.
Risks for the chronic low back pain often obesity, limited muscle mass, poor aerobic conditioning, tobacco smoking and medical comorbidities. Degenerative changes are not reversible, however, patient’s can have significant beneficial effect on chronic low back pain by addressing this aggravating factors.