Lower Back Pain - Anatomy, Physiopathology and Differential Diagnosis/ Moshe Laub B.P.T., D.C.
Low back complaints are a continuing concern for the general population these days, resulting in millions of dollars spent due to absenteeism, lost work, and untold suffering every day. Low back pain (lumbalgia) can affect people of all ages, regardless of their activity levels. Approximately 80% of adults report having low back pain at some point in their lives; however only 14% of those will have complaints lasting longer than two weeks. Unfortunately, low back pain can be a severely debilitating condition and extremely frustrating to cope with.
RELEVANT ANATOMY FOR THE LOW BACK
« Lumbar Vertebrae
« Lumbar Discs
« Lumbar Facet Joints
« Lumbar Spinal Nerves
« Lumbar Spinal Musculature
« Sacroiliac Joint
The lumbar spine contains 5 vertebrae which sit on top of the sacrum. Cortical endplates border the sides of each vertebra, like a lip or ridge, which help hold the intervertebral discs in place. Various muscles and ligaments attach to these bones, which also serve to protect the lower spinal cord and lumbar nerve roots.
The lumbar vertebrae are located between the pelvis and upper torso, and bear much of the stresses and weight of the body. The structural predisposition of absorbing much of the body¡¦s weight results in frequent lumbar vertebral subluxations, misalignments, and improper motion patterns of the lumbar vertebrae. If left uncorrected, these misalignments and faulty biomechanics of the lower spine can result in injury and irreparable degenerative changes.
Lumbar Intervertebral Discs
The lumbar intervertebral disc (IVD) is the cartilage that sits between the vertebrae in your spine, which essentially act as a cushion to absorb the forces as they are distributed through the spine. The discs also serve to protect the facet joints (a.k.a. zygapophyseal joints) from excess forces and degeneration and permit motion between the vertebrae. Each disc contains an outer band of cartilage, called the annulus fibrosus that encompasses an inner gel-like substance called the nucleus pulposus.
90% of all disc herniations affect the 4th and 5th lumbar discs, which affect the L5 and S1 nerves respectively. This is due to the increased pressure and stresses these segments endure under repetitive stress and loads. Disc herniations in the lumbar spine are the most common causes of "sciatica", which refers to pain coursing down the back of the leg in the area of the sciatic nerve. Possible symptoms include pain, muscle spasm, numbness, tingling or weakness in the legs and/or feet.
In rare cases, a lumbar disc herniation can compress the spinal nerves which provide motor control to the bowel and bladder. Although rare, this condition called cauda equina syndrome requires immediate medical intervention. Without immediate decompression the neurological deficits may become permanent. Hence, if you are experiencing severe back pain with loss of bowel/bladder function, please seek emergency medical treatment.
Lumbar Facet Joints
The facet joints (a.k.a. zygapophyseal joints) in the lumbar spine allow for considerable amounts of flexion, and to a small degree, some extension. Side bending and rotation are limited by the vertical orientation of the facets. These joints must withstand large amounts of stress from the body and are subject to acute and repetitive injuries, as well as degenerative arthritis. As degeneration of these joints occur, ligamentous laxity results, which allows for excess movement of the vertebrae and subluxation.
Facet joints are most commonly injured during movements involving a rotational and/or bending component. Pain is often sharp and localized to the area of the affected facet joint. If severe enough, bony arthritic enlargement of the joint (hypertrophy) can impinge upon spinal nerve roots and produce symptoms such as pain, numbness, and tingling down the leg, as well as leg weakness, in addition to back pain.
Lumbar Spinal Nerves
In between the vertebrae and discs lies the intervertebral foramen (IVF), a small hole where nerve roots sit once they exit the spinal canal (which houses the spinal cord). The weakest aspect of the intervertebral discs, posterior and lateral, is proximal to the IVF. Disc injuries commonly result in compressing, stretching or irritating the nerve roots exiting the IVF's. The lumbar spinal nerves innervate structures in the lower extremities, and when irritated the results can be numbness, tingling, pain or weakness in the leg(s) and/or feet.
Lumbar Spinal Musculature
The paraspinal muscles in the lumbar spine attach to the spinal vertebrae, ribs, and pelvis to provide the trunk with movement. These muscles work very hard to stabilize the lumbar spine since there are few ligaments to help do this job. Unfortunately, these muscles are often overworked and more prone to being injured. The pain associated with paraspinal muscle injury may be sharp, dull, boring, or a generalized ache in the area of the lower back, and is often worse with movement.
The sacroiliac joints are located between the sacrum and the ilium bones of the pelvis. These joints may also become irritated or injured resulting in lower back pain, buttock pain, and occasionally leg pain. This is largely due to the fact that the SI joint innervation is from a broad area (L3-S2), involving both the lumbar and sacral nerve plexuses. This joint can be particularly irritated during pregnancy when hormonal changes and pressure from the forming fetus increases the stress on these joints.
LOW BACK CONDITIONS
Lumbar disc herniation
The disc is situated between the spinal bones (vertebrae) and serves as a connector, spacer, and shock absorber for the spine. When healthy, discs allow for normal turning and bending. Discs can bulge, herniate, or rupture, resulting in various degrees of musculoskeletal and neurological sequelae that can impede one¡¦s daily activities. Disc herniation occurs when the outer portion of the disc breaks open or cracks, allowing the nucleus pulposus to escape and push through. This is called a Herniated Nucleus Pulposus (HNP) or herniated disc. In some cases, the torn annulus fibers are the source of pain, but in other cases the herniated disc puts pressure on the spinal nerve root at the intervertebral foramen, which can cause symptoms such as pain, muscle spasm, numbness, cramping, leg weakness, or loss of function. Because the nerve roots in the lumbar spine innervate areas of the thigh, leg and foot, a lumbar disc herniation can cause pain in any one of these areas.
Recent research suggests a primary source of pain from a disc herniation stems from the inflammatory process that occurs as a result from the damage to the disc. The inflammation induces the release of chemicals that irritate the area around the nerve roots, thus causing symptoms along the innervation pathway of that nerve root.
If you suspect that you may have a disc herniation, or something similar, please consult your chiropractor. A chiropractor specializes in the management and treatment of musculoskeletal pathology of the spine and can determine the best course of care for your condition.
Causes/Risk factors for disc herniation:
Repetitive activities - bending, lifting and twisting can irritate the disc over time and cause inflammation of the nerve roots
Sudden loading of the spine while in a flexed position
Underlying degenerative changes of the disc (may or may not be associated with the natural aging process) - natural biochemical changes within the discs contributes to the loss of water and nutrition to the discs, this affects disc strength and resiliency
Lifestyle choices - tobacco use, lack of regular exercise, and inadequate nutrition can contribute to an unhealthy disc
Poor posture ¡V in combination with faulty biomechanical and/or structural function may alter gait pattern and ability to move properly, which stresses the lumbar spine by hindering its ability to distribute load properly and efficiently throughout the body.
Low back pain
Leg pain - often below the knee and into the feet/toes
Sudden onset of pain after a bending, or twisting movement
Previous history of low back pain that resolved on its own
Weakness flexing foot towards the shin, or pointing toes down
Numbness/tingling down leg and/or feet
Pain may be worse with coughing, straining or sneezing
Pain may be worse with slouching and lateral bending
Pain may decrease with leaning towards one side (the one opposite to the pain)
The chiropractic approach to disc problems is to help restore better motion and position to the spinal joints to help reduce the pressure on the IVD. This allows the disc material to migrate back to their normal position, and/ or be reabsorbed by the body, so healing can occur in the tissues surrounding the disc. While conservative chiropractic care can alleviate the pain in most cases, taking proper care of your low back is paramount in ensuring a full recovery. Various chiropractic and conservative techniques are designed to treat lumbar disc syndrome, and the following may be employed to treat such cases:
Spinal decompression therapy (traction)
Electrical modalities (i.e. Interferential, Ultrasound, E-Stim)
Soft tissue therapy (Myofascial release, massage, etc...)
Rehabilitation/spinal stabilization exercises
Clinical practice guidelines for the management of acute low back pain released by the US Department of Health and Human Services (AHCPR) stated:
Conservative treatment such as spinal manipulation should be pursued in most cases before considering surgical intervention;
Prescription drugs such as oral steroids, antidepressant medications and colchicine are not recommended for acute low back problems.
The risk of serious complications from lumbar spinal manipulation is rare
Space occupying lesion (i.e. tumor, hematoma)
Mechanical back pain
Pelvic Inflammatory Disease
Research suggests that conservative treatment, including chiropractic care, yield greater results than traditional medical intervention (such as prescription drugs, surgery). Most patients will experience a reduction in pain and improved function soon after they begin a treatment regimen prescribed by their chiropractor. Surgery for low back pain has very poor outcomes, with complication rates as high as 40%. However, in rare cases, if a patient does not respond to conservative care, or undergoes severe neurological deficit, a referral to a neurosurgeon may be warranted.
Recent studies propose that patients with specific set of findings were determined to have the best chance of response from manipulative therapy. These factors include symptom duration of less than 16 days, lumbar hypomobility, at least one hip internal rotation range of motion >35„a, few symptoms below the knee, and ability to stay active/mobile despite pain.