Examination of Low Back Pain

A review and analysis of data from two US national surveys in 2002 found that 26.4% of respondents reported low back pain lasting at least a whole day in the past 3 months.[1] Lower back pain causes more global disability than any other condition.[2]

A standardized clinical examination of the lumbar spine is critical in the evaluation of patients with low back pain. Progressing in an orderly fashion through the different components of the examination ensures accuracy and repeatability.

Every examination should include inspection of the spine followed by active and passive range-of-motion testing, as well as manual muscle testing at the hip and spine. Finally, special testing and palpation are used to confirm findings appreciated earlier in the examination.

See Back Pain: Find the Cause, Watch for the Comeback, a Critical Images slideshow, to help diagnose and manage this common problem.

Prior to patient contact, the physician should properly wash his or her hands. To complete a proper lumbar spine examination, the physician should be prepared to examine not only the low back but also bilateral hips and both lower extremities.

The examination room needs to be spacious to allow for the patient to move freely. It should also contain a full-length sturdy examination table that will allow the patient to sit comfortably and to lie prone and supine. In addition, a stool on wheels will allow the physician to move easily around the room. The physician should be equipped with a measuring tape, goniometer, and reflex hammer.

Proper patient exposure is critical to any musculoskeletal examination, including evaluation of the spine. Shoes, socks, shirt, and pants need to be replaced with examination shorts and t-shirt or an examination gown. The patient should be given an additional sheet for leg coverage.

The video below is an introduction to the evaluative approach to low back pain.

The initial approach to the patient with acute low back pain is discussed in the video below.

After a detailed history is taken, the physical examination can begin. To start, the physician needs to inspect the entire spine and both lower extremities and gait. Inspection should be followed by range-of-motion testing and manual muscle testing. Finally, palpation and special tests are performed to confirm suspicions. In addition to the musculoskeletal examination, neurological and vascular systems of the lower extremities need to be evaluated.

In the video below, the potential causes and symptoms based on patients’ descriptions of low back pain are discussed.

Standing

The standing inspection needs to be performed in 3 directions: front, side, and posterior. The physician starts at the low back and examines down to the feet. Any exaggerated or flattened normal spinal curves, asymmetries in skin folds or deformities or abnormal curvatures in spine, muscle atrophy, or abnormal hair patterns should be noted.

Seated

The seated examination takes place with the patient seated on the table with knees and hips bent to 90° or seated on the physician’s stool with feet flat on the floor. The physician evaluates for asymmetries of the pelvis.

The video below discusses the initial visual inspection of the patient with acute low back pain.

Lying

For the lying portion of the examination, the patient should be prone on the examination table. In this position, muscle atrophy and leg-length discrepancies can be appreciated.

Leg-length discrepancy

Apparent leg-length discrepancies can be assessed by comparing the distance on either side between the umbilicus and a distal landmark such as the tibial tuberosity or medial malleoli.

True leg-length discrepancy can be assessed by measuring the distance between the anterior superior iliac spine and a distal bony landmark such as the tibial tuberosity or the medial malleolus after ensuring iliac crests are level and any pelvis is perpendicular to the torso.

Gait

To complete the gait inspection, the patient’s gait should be evaluated from the front, side, and posterior aspects. Antalgic gait patterns can be observed from all 3 positions.

Active range of motion of the lumbar spine is evaluated with the patient standing.

The physician should observe motion from the back and side of the patient. The focus is on the lumbar spine; however, motion will also occur at the thoracic and cervical spine. While this phase of the examination is performed, pain and motion limitations should be monitored.

Once full range of active motion is achieved by the patient, gentle pressure can be applied by the physician to check for a further passive range of motion. Extreme care must be exercised when applying pressure, as this could exacerbate the patient’s symptoms.

Motion of the lumbar spine occurs in 3 planes and includes 4 directions, as follows:

• Forward flexion: 40-60°

• Extension: 20-35°

• Lateral flexion/side bending (left and right): 15-20°

• Rotation (left and right): 3-18°

To help ensure motion occurs only at the spine, the physician should sit behind the patient and stabilize the patient by placing his or her hands on the iliac crests and pelvis. By keeping firm control of the patient’s pelvis, additional motion at the ilium can be eliminated. Motion should be smooth and pain-free. Limitations in motion or evidence of pain need to be examined further.

Once standing motion is complete, the patient is placed in a supine position on a table. Hip range of motion needs to be evaluated with a hand on the pelvis to detect any motion that may give a false value owing to tilting of the pelvis. Starting on one side, the physician flexes the patient’s hip and knee both to 90°. Internal rotation (30-40°) and external rotation (40-60°) are performed. This is repeated on the opposite side. Hip pain and motion symmetry are noted.

The video below discusses the role of range-of-motion testing in the evaluation of low back pain.

Strength testing of the lumbar spine includes the muscles around the spine column and the large moving muscles that attach onto the axial skeleton. The goal of muscle testing is to evaluate for strength and reproduction of pain.

To begin, the patient is seated in a neutral position. The physician stands next to the patient and places one arm across the patient’s chest with a hand resting on the anterior aspect of the opposite shoulder. The physician’s other hand is placed in the posterior aspect of the near shoulder. From this position, all motions (flexion, extension, side bending, rotation) can be tested. The patient is instructed to move in one direction, and the physician applies a counter-force to resist all motions. The patient’s strength can be graded.

While the patient is still seated, the lower-extremity muscles that cross the hip joint are tested. The patient is instructed to maintain a set leg position with the hip and knee both flexed to 90°. The physician places his or her hand on the distal thigh and resists hip flexion to test the hip the flexor muscle complex (psoas and iliacus). The physician then places a hand on the lower shin to resist knee extension, testing the quadriceps muscles. Finally, the physician slides his or her hand around the back of the ankle to resist knee flexion, testing the hamstring muscles.

To complete manual muscle testing, the patient is once again placed in a supine position with knees bent. The patient is instructed to perform an abdominal crunch and hold the position for 5 seconds. After holding the position, the patient is instructed to slowly lower back to the table. This motion causes an eccentric muscle contraction of the rectus abdominis muscle.

The physician can use palpation for two purposes during examination of the lumbar spine—to help locate tender areas and, more importantly, to confirm findings previously demonstrated in the examination.

Palpation is begun with the patient seated. The physician should start with the spinous processes. Location can be estimated when the physician’s hands are at the level of the iliac crest. This imaginary line corresponds with the L4-L5 interspace. Palpation along the midline is used to check for bony tenderness and for deformity. Next, the physician moves his or her hands to the muscles just lateral to the spinous processes. The muscles of the erector spinea are palpated for tender points or spasms. With the examiner’s hands in this position, the transverse process, positioned deep to the erector spinea, can also be appreciated.

Once the posterior lumbar spine is evaluated, the patient is instructed to lie prone. From this position, the sacrum, sacral base, sacroiliac joints, and posterior superior iliac spine can be palpated. With the patient in this position, the piriformis and hamstring insertion at the ischial tuberosity also require evaluation.

The patient is instructed to lie supine, and the anterior superior iliac spine, anterior inferior iliac spine, and pubic bones can be palpated.

The role of evaluative palpation in a patient with acute low back pain is discussed in the video below.

These include the straight leg raise test, the Lasegue test, the Slump test, and the femoral nerve traction test.

Straight leg raise test

The straight leg raise test is used to evaluate for lumbar nerve root impingement or irritation. This is a passive test in which each leg is examined individually. It can be performed with the patient in a seated or lying position.

An introduction to and explanation of the straight leg raise test as part of an examination for low back pain is discussed in the video below.

With the patient in the supine position, the knee is extended and the hip is flexed until a complaint of pain or tightness is reached. The leg is then carefully returned to the table and the contralateral leg is tested in a similar fashion. A positive test is demonstrated when reproduction of symptoms radiating down the leg is produced at 30-70° of leg elevation (see video demonstration below).[3, 4, 5, 6] The test has a sensitivity of 91% and specificity of 26%.[4] If pain radiates below the knee, L4-S1 nerve root impingement has been identified.[3]

To perform a seated straight leg raise test, the patient is seated on the examination table with the hips and knees bent to 90° and legs hanging freely over the edge of the table. The physician slowly extends one knee from the 90° starting position. Extension of the leg continues until pain or reproduction of symptoms is appreciated down the tested leg. A positive test result is defined as reproduction of symptoms prior to reaching full extension.

While performing the straight leg raise test, the physician may produce symptoms in the contralateral leg being tested. Reproduction of symptoms in the opposite leg being tested is termed crossed straight leg raise test result (see video below) and indicates a large central lumbar disc herniation. This test has a sensitivity of 28%-29% and a specificity of 88%-90% for nerve root impingement.[4, 7]

Lasegue test

The Lasegue test is also used to evaluate lumbar nerve impingement or irritation. It is performed in the same fashion as the straight leg raise test, and the setup is the same as that for the lying straight leg raise. The one modification is that, once a complaint of pain or tightness is reached, the leg is slowly lowered 5%-10% or until radicular symptoms vanish.[7]

While holding the leg in this lowered position, the examiner dorsiflexes the foot. A positive Lasegue test result is demonstrated with reproduction of symptoms in this modified position. In the literature, the methods for performance of this test vary, leading to a sensitivity of 35%-97% and a specificity of 10%-100%.[7]

Slump test

The Slump test is used to evaluate for lumbar nerve root impingement or irritation. It begins with the patient seated on the table with both hips and knees positioned at 90°. The examiner stands to the side of the patient. The patient is instructed to slump forward while maintaining the head and neck in neutral position. The physician extends one leg with one hand while using the other hand to apply overpressure to the patient’s thoracic spine; thus exacerbating the curvature of the spine. Once in this position, the patient is instructed to lower the chin to the chest, producing cervical flexion.[8]

A positive Slump test result is demonstrated with the reproduction of radicular symptoms. The sensitivity ranges from 44%-84% and has a specificity of 58%-83%.[7]

The test is then repeated on the contralateral side.

Femoral nerve traction test

The femoral nerve traction test is used to evaluate for pathology of the femoral nerve or nerve routes coming out of the third and fourth lumbar segments.

The setup begins with the patient lying on the unaffected side with the unaffected limb slightly flexed at the hip and knee. The patient’s back is in a non-hyperextended position. While the patient’s neck is slightly flexed, the examiner passively extends the hip while standing behind the patient. Finally, the examiner flexes the knee, putting tension on the femoral nerve. Reproduction of radicular symptoms down the anterior thigh demonstrates a positive test result.

Case reports in the literature correlate a positive femoral traction test result in 84%-95% of patients with nerve impingement; however, tight iliopsoas or rectus femoris muscles can lead to false-positive results.[9]

These include the one leg standing test (stork stand) and the Patrick-FABER test (flexion abduction external rotation test).

One leg standing test (stork stand)

The one leg stand test, or stork stand test, is used to evaluate for pars interarticularis stress fracture (spondylolysis).

It begins with the physician seated behind the standing patient. The physician stabilizes the patient at the hips. The patient is instructed to flex one leg at the hip and knee as if taking a marching step. While holding this position, the patient is asked to arch his or her back into extension. Reproduction of pain on the stance leg is a positive finding. The test is then repeated on the contralateral side.

The sensitivity of this test is 50%-55%, and its specificity is 46%-68%.[10]

Patrick-FABER test (flexion abduction external rotation test)

The flexion abduction external rotation (FABER) test is used to evaluate for pathology of the sacroiliac joint. The patient lies supine on the examination table and is asked to place one foot on the opposite knee (placing the hip in flexion abduction external rotation). While supporting the pelvis with one hand, the physician presses firmly down on the flexed knee while supporting the pelvis at the opposite anterior superior iliac spine.

A positive finding or this test is pain in the sacroiliac joint of the leg being tested. One study found the sensitivity to be 54%-66% and the specificity to be 51%-62%.[11]

This consists of the Trendelenburg test.

Trendelenburg test

The Trendelenburg test is used to evaluate for weak or injured gluteus medius and minimus muscles.

It begins with the patient in a neutral stance. The physician is seated behind the patient with his or her hands placed behind the patient’s hips with the thumbs resting on the posterior superior iliac spine. The patient is instructed to flex at the hip, raising the knee as if taking a marching step. With the patient in this stance, the physician evaluates for pelvic drop on the side opposite the stance leg. If a pelvic drop is observed, pathology of the stance leg gluteus medius and minimus has been identified.

This consists of neurological examination, Babinski test, Oppenheim test, cremasteric reflex, and vascular examination.

Neurological examination

The neurological examination is a crucial step in the lumbar spine evaluation. The spinal cord and the nerve roots can contribute to or cause lumbar pain. The neurological examination consists of 3 elements: motor, sensory, and reflex. The examination is performed with the patient seated in a neutral position.

Table 1. Myotome Testing (Open Table in a new window)

To test the myotomes, the standard grading scale can be used, as follows:

• Grade 0 - No contraction or muscle movement

• Grade 1 - Trace contraction with no movement at the joint

• Grade 2 - Movement, but not against gravity

• Grade 3 - Movement against gravity but not added resistance

• Grade 4 - Movement against resistance, but less than normal

• Grade 5 - No detectable weakness

The physician should test myotomes along the entire length of the lower extremity and compare bilaterally.

When the physician tests sensory distribution, the patient is asked to close his or her eyes. The physician should use equal pressure throughout the examination. If general sensation is intact and more specific testing is needed, the patient can be challenged with discrimination between sharp and dull objects.

Reflex testing concludes the neurological examination. The examiner has the patient clasp his or her hands together and perform a pulling maneuver. This helps distract the patient and prevents overriding the reflex testing. While holding a reflex hammer, the physician delivers a quick strike to the tendon. To test the L4 reflex, the patella tendon is struck just inferior to the patella tendon, monitoring for knee extension. When testing the S1 reflex, the Achilles tendon is struck, monitoring for ankle plantar flexion. The response is monitored and graded and compared bilaterally (see video demonstration below).

Other components of the neurologic examination are discussed and demonstrated in the videos below.

The grading system for reflex testing is as follows:

• Grade 0 - Absent

• Grade 1+ - Diminished

• Grade 2+ - Normal

• Grade 3+ - Hyperactive without clonus

• Grade 4+ - Hyperactive with clonus

To complete the neurological examination, the physician should test the patient for an upper motor lesion or pyramidal tract injury.

Babinski test

The patient is placed in the supine or seated position. The physician runs a pointed object along the plantar aspect of the patient’s foot. Involuntary extension of the great toe and abduction of the other toes is considered a positive result.

Oppenheim test

The patient is placed in the supine or seated position. The physician runs a pointed object along the anterior crest of the patient’s tibia. Involuntary extension of the great toe and abduction of the other toes is considered a positive result.

Cremasteric reflex

This reflex test is performed only on male patients. The patient is placed in the supine position, and the physician gently strokes the patient’s medial upper thigh with a pointed object while observing the scrotum. Absence of the scrotum retracting is a positive result.

Vascular examination

To complete the examination, the physician should evaluate the vascular system. This is accomplished by checking peripheral pulses of dorsal pedal artery and tibialis posterior artery. Besides noting presence of a pulse, the character can be compared bilaterally. Finally, capillaries of both feet are checked.