Lumbar spine (Benchmark exam)

With your patient standing, inspect from the back and the side, observing:

• Curvature of the spine.
  • From behind, any lateral curvature of the spine is abnormal and suggests scoliosis.
  • From the side, you should expect to see typical lumbar lordosis
• Muscle bulk should be symmetric side to side.
• Swelling, erythema or ecchymosis suggests trauma or infection.
• Asymmetry of hip or shoulder height suggests scoliosis or leg length differences.

Palpation

Palpate the low back, carefully noting any structures that are tender or asymmetric.

• Vertebrae from L1 to the sacrum
• Paravertebral muscles bilaterally
• Sacroiliac joints

Range of Motion

Test range of motion in 4 directions. Normal range of motion for the lumbar spine is:

• Flexion:  60 to 90 degrees
• Extension: 25 to 30 degrees
• Lateral rotation (twisting): 25 degrees
• Lateral bending: 25 to 35 degrees

Neurovascular testing

Patients with non-specific back pain should have a normal lower extremity neurologic exam. Weakness, numbness or reflex changes are red flags for involvement of nerve root(s) or spinal cord.

Strength

You can assess lower extremity strength by testing each muscle group in isolation or with functional tests like squatting, standing, and heel and toe walking.

Sensation

To screen, test sensation at several points on each leg.  If you are concerned about involvement of a specific nerve root, use the diagrams below to choose the key points at which to test sensation.

Reflexes

Test the patellar, Achilles, and plantar reflexes.  Increased or decreased reflexes suggest different causes of back pain.

• Compression of nerve roots causes a lower motor neuron injury and decreased reflexes.
• Compression of the spinal cord causes an upper motor neuron injury and increased reflexes. Upper motor neuron injury also causes an upgoing toe on testing of plantar reflexes (positive Babinski).

Hypothesis Driven Physical Exam

If you are concerned about a lumbosacral radiculopathy

Lumbosacral radiculopathy is a common cause of back pain, usually radiating down one leg.  It’s caused by impingement of a nerve root by a herniated intervertebral disc or an osteophyte. The most commonly involved nerve root is L5, followed by S1 and L4.

Findings specific to disc herniation at each level are:

	Pain	Numbness	Weakness	Decreased Reflex
L4	Back to medial thigh, medial ankle and foot	Medial calf and ankle	Quadriceps, tibialis anterior	Patellar
L5	Back to back of leg, lateral calf, and classically, big toe	Dorsum of foot and big toe	Big toe extension, foot dorsiflexion, thigh abductors	No reflex associated with L5
S1	Back to back of leg, lateral ankle and sole	Lateral ankle and bottom of foot	Plantar flexion and thigh extension	Achilles

To efficiently assess for findings of lumbar radiculopathy, test each of the following with the patient seated:

• Inversion of the foot/ankle
• Extension of the great toe
• Eversion of the foot/ankle

• Reflex at the patellar tendon
• Reflex at the Achilles tendon

• Sensation at key sensor points below

Straight leg raise (SLR)

With the patient supine, the examiner lifts the leg with the knee straight. If a bulging disc or osteophyte complex is present, this maneuver will stretch the L5 and S1 nerve roots over it, reproducing pain that radiates down the leg (not just to the back or hip).

• The SLR is positive if it reproduces pain in the lifted leg at < 70 degrees of hip flexion.  This finding has a high sensitivity but a low specificity. If the SLR is negative, it argues strongly against lumbosacral radiculopathy.
• The crossed SLR is positive if pain is reproduced in the opposite leg. This test has a low sensitivity but a high specificity.  If positive, it supports a diagnosis of lumbosacral radiculopathy.