Mechanical back pain: Clinical sciences

Mechanical back pain refers to pain arising from the joints, intervertebral discs, nerves, and soft tissues of the spine. It accounts for the majority of back pain cases, with etiologies ranging from benign musculoskeletal causes to conditions associated with severe neurological deficits.

Now, let’s take a moment to review the anatomy of the spine, starting with the vertebra itself. The anterior portion is known as the vertebral body, while the vertebral arch makes up the posterior and lateral aspects. Projections from the vertebral arch include the spinous and transverse processes as well as the articular processes that make up the facet joints. The pedicles are the bony elements connecting the body to the arch, while the lamina connects the transverse and spinous processes. This circle of bone creates the spinal foramen, and when joined together, adjacent vertebrae form the spinal canal.

Laterally, the intervertebral neuroforamen is formed. The intervertebral disc lies between each set of adjacent vertebrae, creating the anterior intervertebral articulation, while the paired facet joints are located posteriorly. Now, several ligaments stabilize these articulations, including the ligamentum flavum, which attaches to the anterior surface of each vertebral arch. Finally, the spinal cord courses through the spinal canal and gives off spinal nerves at each intervertebral level, which exit through the neural foramen.

Okay, if your patient presents with chief concern suggesting mechanical back pain, first perform a focused history and physical examination. Your patient will report back pain, while the physical exam might reveal tenderness to palpation of the spinal and paraspinal structures, as well as hypertonicity of surrounding musculature.

At this point, you can diagnose mechanical back pain, so your next step is to assess your patient for red-flag signs and symptoms! These include age of onset before 20 or after 55 years of age; severe or progressive motor and sensory loss; urinary retention or incontinence; history of cancer or spinal surgery; significant trauma that precedes the onset of pain; prolonged steroid use; and history of HIV. Okay, if red flag symptoms are present, obtain a spinal X-ray and assess for the underlying cause.

First, let’s discuss spinal fracture! Most often, you’ll have an elderly patient who reports localized back pain that worsens with bending. They might have a history of trauma, corticosteroid use, osteoporosis, cancer, or an inflammatory disease like ankylosing spondylitis. Additionally, the physical exam reveals localized tenderness to palpation over the spinous process, while the spinal X-ray typically shows a vertebral deformity. At this point, you should suspect a spinal fracture, so order a spine CT and MRI. CT is preferred to evaluate bony abnormalities, and can confirm the diagnosis of spinal fracture, while MRI is better for visualizing soft tissue abnormalities like impingement of neural elements!

Treatment consists of lifestyle modifications, primarily rest and a brace to help stabilize the spine. Another important part of treatment is physical therapy, as well as pharmacologic therapy, starting with NSAIDs or acetaminophen. If pain persists, consider adjuvant medications or a short trial of opioids. Additionally, if your patient has osteoporosis, consider medications like bisphosphonates. Finally, don’t forget to consult your surgical team for possible vertebroplasty or kyphoplasty.

Now moving on to spinal stenosis! Your patient will report pain, sensory loss or weakness in their back, buttocks, and legs that’s generally worse with extension, such as standing and walking, but relieved by activities that create flexion, such as sitting or leaning forward, like pushing a shopping cart. The physical exam could reveal focal weakness, sensory loss, and decreased deep tendon reflexes. Additionally, spinal X-ray might show degenerative changes, loss of intervertebral space, and possibly a vertebral fracture or deformity.

With these findings, suspect spinal stenosis and order an MRI! If the MRI reveals a narrowing of the spinal canal with possible impingement of neural elements, you can diagnose spinal stenosis! Treatment includes lifestyle modifications, physical therapy, and pharmacologic therapy to help manage pain. Finally, don’t forget to consult your surgery team for possible treatment options, such as laminectomy.

Okay, now let’s move on to disc herniation! These patients report midline pain that increases with spinal flexion, with possible radiation to the buttocks and legs. On the flip side, the physical exam might reveal dermatomal sensory loss or myotomal weakness, decreased deep tendon reflexes, or a positive straight leg raise test. To perform this maneuver, position the patient supine and raise their straightened leg to at least 80 degrees. If the patient reports reproduction of the radicular pain, the test is positive. These findings suggest the presence of nerve root impingement.