What structures in the lower back can cause pain?

The lower back contains multiple pain-generating structures including bones, discs, ligaments, nerves, and muscles. Because the back is the most common source of pain in the body, understanding these anatomical components is essential for accurate diagnosis. Pain location often suggests the underlying cause, making careful examination critical for identifying which structure is responsible.

What are the main components of a lower back examination?

A comprehensive lower back exam includes inspection and palpation to assess for deformity and inflammation, evaluation of range of motion, testing muscle strength innervated by lumbar-sacral nerves, neurological evaluation, and special tests like the Stork test and Patrick's test. These components work together to identify structural and functional abnormalities.

Why is palpation important in lower back examination?

Palpation allows clinicians to detect signs of deformity and inflammation by direct physical examination of back structures. Combined with inspection, palpation provides tactile feedback about tissue quality, tenderness, and abnormal findings that guide diagnosis. This hands-on assessment is fundamental to identifying the source of lower back pain.

How does testing muscle strength relate to lower back examination?

Testing muscle strength in the lower back evaluates the function of muscles innervated by nerves exiting the lumbar-sacral spine. Weakness or asymmetry in strength can indicate nerve compression, muscle injury, or neurological dysfunction. This assessment helps localize pathology and determine whether nerve involvement is present.

What does range of motion testing reveal in a lower back exam?

Range of motion testing measures the back's flexibility and identifies restrictions that may indicate pain, muscle tightness, or structural limitations. Decreased motion in specific directions can suggest disc pathology, facet joint involvement, or muscle guarding. ROM assessment helps characterize the functional impact of lower back conditions.

What is the purpose of special tests like the Stork test and Patrick's test?

Special tests such as the Stork test and Patrick's test are targeted maneuvers designed to reproduce or elicit specific lower back pain patterns. These tests help differentiate between various causes of pain by stressing particular structures or nerve pathways. Positive findings guide clinicians toward specific diagnoses and treatment approaches.

Why is neurological evaluation essential in lower back examination?

Neurological evaluation assesses nerve function and detects signs of nerve compression or damage in the lumbar-sacral region. This includes testing reflexes, sensation, and motor function to identify pathways and peripheral nerve distribution abnormalities. Neurological findings help determine whether nerve involvement is contributing to the patient's symptoms.

Lower Back Exam

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1. Inspection

Inspection should be done with the patient standing, while observing from behind. Have the patient remove enough clothing so the entire back and sacral area can be properly inspected.

Inspect the entire back for redness, asymmetry, deformity, scoliosis, or abnormal hair growth.
From the side, observe lumbar lordosis, which normally appears as a gentle, reverse C-shaped curve of the spine.

2. Palpation

Palpate for areas of tenderness. Important areas to check include:

Spinous processes: These are the hard bony structures that run down the midline of the back. Look for a step-off at L4-S1, which is suggestive of spondylolisthesis.
Paraspinous muscles: These are the muscles that run along either side of the spinous processes and are often tender with overuse of the back.
Sacroiliac (SI) joint: Palpate below and lateral to the posterior superior iliac spine.
Sciatic notch: The sciatic notch is located midway between the posterior superior iliac spine (which is the posterior tip of the iliac crest) and ischial tuberosity. Push here to aggravate pain caused by sciatica.
Iliac crests: Place your hands on both iliac crests, and compare their height. If one hand sits higher than the other, it may suggest leg length inequality or scoliosis.

3. Range of Motion (ROM)

Evaluate the ROM of the back. Look for deficits or excessive pain. Key motions include:

Forward flexion (normally 80-90°): To evaluate, have the patient bend forward to touch the toes. This loads the discs, which makes it more likely to increase disc pain. Be sure to observe from behind when the patient is bent forward to look for asymmetry of the back, which is suggestive of scoliosis.
Extension (20-30°): Have the patient bend straight backward as far as possible. This loads the facets, which makes it more likely to increase facet pain.
Lateral bending (20-30° in each direction): Assess by having the patient bend, first to one side and then the other. This stretches the muscles and is more likely to aggravate pain from muscle strain.
Twisting (30-40° in each direction): Have the patient (standing) rotate as far as possible, first to one side and then the other. This also stretches the muscles and increases pain from the source.

4. Strength Testing

Evaluate the strength of the muscles innervated by the key nerve roots exiting in the lumbar-sacral spine. Weakness suggests irritation of these nerve roots from disc or bony pathology. These include:

Heel walking (anterior tibial muscles; L4): Ask the patient to walk a few steps on the heels.
Toe walking (gastrocnemius soleus muscles; S1): Ask the patient to walk a few steps on the toes.
Resisted great toe dorsiflexion (L5): Ask the patient to sit and lift the big toe up against your resistance, pressing down on the top of the toe.

5. Neurologic Exam

Conduct a focused neurologic exam in patients with lower back pain.

Deep tendon reflexes (knee jerk - L4 nerve root; ankle jerk - S1 nerve root): Tap a reflex hammer briskly against the patella and Achilles tendons, comparing side to side.
Ankle clonus: Elicit ankle clonus by sudden passive ankle dorsiflexion, which may result in repetitive and uncontrolled ankle twitches. This suggests an upper motor neuron lesion, such as proximal spinal cord compression.
Straight-leg raise: Lift the patient's leg, with the knee extended, in the sitting (or supine) position. Pain radiating past the knee suggests sciatica, likely caused by disc herniation in the lumbar-sacral area (L5 and S1 nerve roots). Dorsiflexion of the ankle during the straight-leg raise test increases sciatic tension and pain, while plantar flexion relieves sciatic tension and pain.
Crossed straight leg raise: Do a straight-leg raise test on the opposite, uninvolved leg. If this maneuver aggravates the pain in the opposite leg, it is suggestive of sciatica.
When cauda equina syndrome is suspected, consider a rectal exam to check for decreased sphincter tone and perianal sensation.

6. Special Tests

Special tests in the back include:

Stork test (one-leg standing hyperextension test): Have the patient hyperextend the back while standing on one leg. This position aggravates pain associated with spondylolysis, spondylolisthesis or SI joint dysfunction.
Patrick's or the flexion, abduction, and external rotation (FABER) test: Place the patient's hip and leg into the figure-of-four position (flexion, abduction, and external rotation). This position aggravates SI joint pain.