Back pain is the second most common reason for office visits in the United States and as much as 84% of the population suffers from lower back pain during their lifetime. It accounts for 2.5% of all medical visits. The term “chronic lower back pain” encompasses several disease entities with unique pathology and treatment options.
When a patient presents with lower back pain, the location of the pain is extremely important to identify. There are two categories that describe the type of back pain. Referred pain is pain in structures that have the same mesodermal origin. In other words, their localized injury does not signify any compression of neurons or nerve roots. Referred pain is commonly described as dull or deep pain, and may present with referral most commonly into the buttocks or posterior thigh. Radicular pain is described as sharp, stabbing, shooting, or lancinating pain that courses down to the foot, also associated with paresthesia due to the mechanical compression of a nerve root. L5 and S1 are the most common nerve roots affected in radicular pain.
While conducting a physical examination, it is important to focus on the location of the pain, its characteristics, as well as other neurologic deficits associated with the pain.
In radiculopathic pain, there are various mechanical maneuvers to tighten the sciatic nerve, which further compress an inflamed lumbar root against a pathologic finding, such as a bony spur or herniated disk. The most common of these tests is the straight leg raising test (SLRT), which is conducted with the patient in the supine position. While the patient’s leg is extended and the ankle dorsiflexed, the patient’s leg is raised. A positive test will reproduce radicular symptoms at 10–60 degrees of elevation. It is important to note that the radicular pain must travel all the way down to the raised foot in order to call it a positive test. The SLRT’s level of reliability is age-dependent. For example, in a young patient, a negative test will most likely rule out a herniated disk, but after the age of 30, a negative test cannot reliably exclude a diagnosis.
A thorough physical examination should also include evaluation of other specific problems that may present as lower back pain, including peripheral vascular disease, abdominal pain, or hip joint disease.
During the first visit, radiographs are not indicated. However, if the patient returns with pain refractory to medical management and physical therapy, a plain radiograph should be ordered to rule out tumor, or a magnetic resonance imaging (MRI) can be ordered to rule out disk herniation if the patient is having radicular pain.
COMMON LUMBAR PATHOLOGIES
There are many pathologic findings that can contribute to lower back pain involving the lumbar spine. The most commonly seen include: