Inspection (Video 7-1 )

Examination of the low back begins with the initial observation of the patient, noting the patient’s preferred position while awaiting the physician. Patients with uncomfortable discogenic and radicular pain may be noted to be standing or moving as opposed to being seated while they wait. At other times, patients with LBP will maintain rigid postures, and motions will be noted to be hesitant to avoid bending or twisting, which may exacerbate their pain. An antalgic or listing posture should be noted if present. Patients should disrobe to either an examination gown or disposable examination shorts with an easily removed top to allow complete visualization.

Bony landmarks are useful in determining site of pain in the lumbar spine. Important landmarks include the anterior superior iliac spine (ASIS) at the level of the sacral promontory and the PSIS at the level of the spinous process of the second sacral vertebra. A commonly used reference line is created by passing a horizontal line connecting the highest points of both iliac crests, which crosses the vertebral column at the level of the L4 to L5 intervertebral space or the L4 vertebra. Notably, Duniec and coworkers performed a recent study comparing palpation guided identification of this line by an anesthetist with ultrasound evaluation before lumbar puncture and found that in 36% of cases, the palpatory exam was off by a mean of one level. This study corroborated similar results found by Locks et al. in 2010, who found that the L3 to L4 space determined anatomically in the seated position in obese and nonobese women undergoing elective cesarean section was only 49% and 53% accurate, respectively, when confirmed with ultrasound evaluation.

Forming a line through the tubercles of the iliac crests creates the intertubercular plane, which cuts the body of the fifth lumbar vertebra. The upper margin of the greater sciatic notch is opposite the spinous process of the third sacral vertebra, and slightly below this level is the posterior inferior iliac spine (PIIS). The surface markings of the posterior inferior iliac spine and the ischial spine are both situated in a line that joins the posterior superior iliac spine to the outer part of the ischial tuberosity; the posterior inferior spine is 5 cm and the ischial spine 10 cm below the posterior superior spine; the ischial spine is opposite the first portion of the coccyx. With the body erect, the line joining the pubic tubercle to the top of the greater trochanter is practically horizontal; the middle of this line overlies the acetabulum and the head of the femur.

Patients should be observed from the front, side, and rear. Anterior observation should assess head position, height symmetries of the shoulders and iliac crests, patellar directionality, and lower limb positioning. The head should sit straight on the shoulders, which themselves should be of equal height, although the hand-dominant side may be slightly lower in athletic or sporting individuals. ( Fig. 7.4A ). The iliac crest height should be equal ( Fig. 7.4B ). The patellae should be pointing anteriorly and the lower limbs straight, with any deformity such as valgus–varus misalignment noted.

Inspection. A, Assessment of shoulder height. B, Assessment of iliac crest height.

Posterior observation involves inspection of spinal, bone, and soft tissue alignment. Shifting of the pelvis or shoulders may be noted in the face of nerve root injury or gluteus medius weakness, similar to a Trendelenburg sign. With a disc herniation lateral to the nerve roots, the patient may list away from the side of the irritated nerve root in an attempt to draw the nerve root away from the disc; this is termed a lateral shift. When the herniation is medial to the nerve root, the patient may list toward the side of the lesion. The reliability of lateral shift judgments was examined by Clare and others in different levels of physical therapists with training in the McKenzie method using stable photographic slides of 45 patients with LBP, and it was found that lateral shift judgments had only moderate reliability (intraclass coefficient [ICC] range of 0.48 to 0.64).

Scoliotic curves may be evaluated by inspection of the height of the shoulders, scapula, and iliac crests. The spines of the scapulae begin at the level of the third thoracic vertebra (T3) and should be at the same angle. The inferior angles of the scapula (T8) should be equidistant from the spine. Any curve in the spine should be noted, as well as muscular asymmetry. A rib hump deformity can be noted with trunk forward flexion or may be seen through apparent scapular winging. The waist angles should be equal. Comparing the heights of the iliac crests or posterior superior iliac spines for any differences may identify pelvic obliquity, which could indicate a functional leg length discrepancy, or may stem from a spinal deformity such as scoliosis or an anomalous vertebrae. The relationship between the PSIS and the ASIS should be noted to assess for level of pelvic tilt. In addition, the gluteal folds and popliteal creases should be level.

Upon examining a patient from the side, the ear should drop a plumb line even with the tip of the shoulder and the peak of the iliac crest. A gentle lumbar lordotic curve is normal. Any exaggerated or increased curve should be noted. Exaggerated lordosis may be associated with a hip flexor contracture, weak hip extensors, or spondylolisthesis. The alignment of the lower extremities should also be observed from the side in neutral stance.

The skin may reveal ecchymosis after blunt trauma, erythema with infection or inflammation, or rashes with shingles or infection. Atrophy of the tissues may be noted with the presence of nerve root or peripheral nerve injury.

Palpation

Palpatory examination in ambulatory patients begins in the standing position, usually with the examiner placing their fingers along the tops of the iliac crests with thumbs directed toward the midline L4 to L5 interspinous level. Palpation as such will allow further assessment of iliac crest height and symmetry in patients with obese body habitus that obscures visual examination. While the patient is standing, the spinous processes are palpated sequentially, not only to evaluate for pain but also for the presence of a possible step-off deformity from one level to the next, which may be indicative of spondylolisthesis. Palpation of the paraspinal musculature is performed to identify tender or trigger points as well as regions of muscle spasm; tenderness may be found in regions of referred pain such as the gluteal musculature. Midline palpation may elicit pain with symptomatic intervertebral disc disorders. Tenderness to palpation or percussion of the vertebrae should be noted because it may be suggestive of metastasis, compression fractures, or osteomyelitis and should be correlated with the patient’s history. Deyo and others described palpation of soft tissue and bony tenderness as having both poor reproducibility (kappa coefficient [κ] = 0.40) and specificity; however, it is essential to perform. To complete the examination, palpation of the posterior superior iliac spines, iliac crests, the greater trochanters, and ischial tuberosities are all important in localizing the etiology of the patient’s symptoms.

Range of Motion

Lumbar ROM is used to measure impairment and identify restrictions in patients with LBP. The literature supports greater accuracy of passive range assessment over active range assessment. Motion must be assessed in all planes, document any side-to-side differences. ROM may be affected by age and sex. Total sagittal ROM, flexion angle, and extension angle decline as age increases. A comprehensive normative database of lumbar ROM indices was determined by Troke and associates, who examined 405 asymptomatic subjects ( Table 7.1 ).

Mellor and colleagues found greater variations in proportional motion between lumbar vertebrae in subjects with LBP versus controls using quantitative fluoroscopy. In a systematic review and meta-analysis, Laird and associates found that on average, persons with LBP have reduced lumbar ROM and proprioception and move more slowly than healthy counterparts.

Studies have measured lateral flexion from different reference points, which has led to differing normative data. Using T12–L1 to L5–S1 as the reference points for measuring lateral flexion, the range on both sides was 49 to 77 degrees, and Pearcy and associates measured the segmental ROM of the spine ( Table 7.2 ).

A common starting measurement is forward flexion, which is composed of both lumbar and pelvic movement. It is generally considered that the first 60 degrees takes place in the lumbar spine, while any further motion takes place in the hips; however, strict measurements validating this have not been performed. Torso flexion is accomplished with a combination of hip and lumbar spine motion. Caillet has demonstrated that the initial 45 degrees of trunk flexion is essentially the reversal of lumbar lordosis and that the remainder of the motion is a result of pelvic rotation.

Radiographic analysis is considered the gold standard for determining ROM; there is no physical examination gold standard to measure ROM of the lumbar spine in the peer-reviewed literature. Studies have used external measurements with comparison with plain radiographs with inconsistent findings. Mayer and coworkers and Saur and associates have found good correlation between these measurements. Mayer and coworkers found no significant differences between radiographic ROM measurements and noninvasive inclinometer techniques. Saur and associates found a very close correlation ( R = 0.93) of ROM taken with and without radiologic evaluation using an inclinometer. A systematic review by Littlewood and May indicated limited positive evidence that the double inclinometer method is valid for measuring total lumbar ROM, conflicting evidence for double inclinometer measurement of flexion range, and limited evidence that the modified–modified Schober test is not valid for measurement of lumbar flexion range.

Modified Schober Test

In 1969, Moll and Wright modified the Schober technique for the assessment of patients with ankylosing spondylitis and others, with the addition of a mark 5 cm below S1. It is described as follows:

With the subject standing erect but relaxed, a point is drawn with a skin marker at the spinal intersection of a line joining the dimples of Venus (S1). Additional marks are made 10 cm above and 5 cm below S1. Subjects are asked to bend forward. The distance between the marks 10 cm above and 5 cm below S1 is measured.

The rationale for this modification was an observation that, on forward flexion, both the lumbosacral junction and superiorly placed 10-cm skin marks tended to move less relative to the spinous processes and the skin than the previously used mark 5 cm inferior to the sacrum ( Fig. 7.5 ).

A, Modified Schober technique (neutral standing). B, Modified Schober technique (full flexion).

Reynolds found this measurement of motion to have good reliability in flexion and extension, with reasonable variation in flexion. Fitzgerald and others reported a Pearson correlation coefficient of 1.0 for lumbar flexion and 0.88 for lumbar extension in a study of young healthy subjects. Rezvani and associates found that the modified Schober test reflected spinal mobility better than the original Schober test.

Gill and colleagues concluded that the modified Schober method was the most reproducible method of measurement. The coefficient of variation (CV) was excellent, ranging from 0.9% for flexion and 2.8% for extension.

Miller and associates noted overall good interrater reliability ( R = 0.71) of the modified Schober method. Potential errors that affect the reliability of this clinical test were (1) the presence or absence of dimples of Venus, (2) anatomic location of the dimples of Venus, (3) anatomic variability of the 10 cm line, (4) problems introduced by skin distraction, and (5) problems in developing a normative database. Stankovic and coworkers noted an intrarater correlation coefficient of 0.95 and an interrater correlation coefficient of 0.94 utilizing the modified Schober test. Thomas and others determined the specificity to be 95% and sensitivity to be 25% when comparing patients with and without LBP.

Viitanen and associates compared the modified Schober test with the thoracolumbar flexion measure using a simple tape method and correlated the results with radiologic changes in patients with ankylosing spondylitis (AS). The Schober test and tape methods correlated fairly highly (modified Schober R = 0.71, 0.62; tape method R = 0.49, 0.42) with radiologic changes. Macrae and Wright found the validity of modified Schober against radiographs was strong ( r = 0.97) while Rahali-Khachlouf found it to be moderate ( r = 0.59).

In conclusion, the modified Schober test has been found to be moderately reproducible and specific but not sensitive when examining patients with and without LBP, and at least moderately reflects lumbar spine motion compared to radiographs.

Manual Motor Testing (Video 7-2 )

Strength assessment is typically performed in a sequential manner, evaluating muscle groups innervated by different peripheral nerves and nerve roots. Lumbar radiculopathy is usually characterized by weaknesses affecting two or more muscles from the same spinal segment but different peripheral nerves. For example, an L5 radiculopathy may affect both the dorsiflexors of the foot and toes (peroneal nerve) and abduction of the hip (superior gluteal nerve). The strength examination should include the assessment of the hip flexors (L1–L3), quadriceps (L2–L4), tibialis anterior (L4–L5), extensor hallucis longus (L5), and gastrocnemius-soleus (S1). The latter muscle may be assessed via the performance of 10 toe raises (unilaterally) or the ability to ambulate on toes. Functional testing of the hip abductors should be performed with the patient standing on one leg to evaluate for the presence of a Trendelenburg sign, noted as a sagging of the iliac crest on the unloaded side.

Several studies have looked at the sensitivity and specificity of muscle strength testing in patients with lumbar radiculopathy ( Table 7.4 ). Kerr and coworkers demonstrated reduced ankle dorsiflexion in 54% and plantar flexion in 13% of those with lumbar disc protrusions from L4 to S1 with an overall specificity of 89%. Weakness of the extensor hallucis longus had a sensitivity of 12% to 51% with a specificity of 72% to 91% for detecting L5 radiculopathy, whereas weak ankle plantar flexors had an overall specificity between 26% and 99% in detecting S1 radiculopathy. In a cross-sectional study, Ortiz-Corredor correlated physical exam findings to abnormal electromyogram (EMG) findings in LBP patients and found weak plantar flexors were highly specific (97.5%), but weak quadriceps were poorly sensitive (35.67%). In a small retrospective chart review of 28 patients, Iizuka and colleagues found that the most common condition causing a foot drop (manual muscle testing grade of 0 to 3) was compression of two nerve roots. A systematic review and meta-analysis by Al Nezari and others in 2013 determined that motor testing for paresis showed low pooled sensitivities (22% to 40%) and moderate specificities (62% to 79%) for surgically and radiologically determined disc herniations, while motor testing in muscle atrophy exhibited a pooled sensitivity of 32% and a specificity of 76% for surgically determined disc herniations.

Sensory Examination (Video 7-3 )

The sensory exam should cover the bilateral lower extremities to evaluate for true dermatomal or more diffuse sensory loss as seen in peripheral neuropathies with a “stocking” distribution of loss. Dermatomes define the area of skin innervated by a single nerve root or peripheral nerve ( Fig. 7.6 ). Sensation can be evaluated using many different modalities, including vibration, proprioception, temperature, light touch, and pinprick. The latter two are more commonly used in the neurologic evaluation, although vibration may be more sensitive for injury to large-diameter sensory nerves and proprioception loss may be indicative of posterior column dysfunction such as vitamin B ₁₂ deficiency and syphilis. The sensitivity and specificity of the sensory examination in the diagnosis of lumbar disc herniation has been described in the literature (see Table 7.4 ). Suri and coworkers examined pinprick testing at the anterior thigh, medial knee, medial ankle, great toe, and lateral foot for sensitivity and specificity for mid lumbar and low lumbar nerve root impingement as well as level-specific nerve root impingement. For mid lumbar and low lumbar impingement, sensitivities ranged from 0% to 21%, though specificities ranged from 79% to 100%, with the highest specificities and significant likelihood ratios observed for the medial knee and medial ankle in mid lumbar nerve root impingement. For level-specific impingement, anterior thigh pinprick sensation was 50% sensitive and 96% specific and had a positive likelihood ratio (LR) of 13 for L2 impingement, while medial ankle pinprick was 31% sensitive and 100% specific and had an LR approaching infinity for L4 nerve root impingement.

Dermatomes and peripheral nerve distribution of the lower extremities.

(Adapted with permission from Borenstein, Wiesel, and Boden; Low Back and Neck Pain: comprehensive diagnosis and management. 3rd edition (2004). Chapter 5, Figure 5-14, page 123.)

Reflex Examination (Video 7-4 )

A reflex is the involuntary contraction of muscles induced by a specific stimulus. Tendon reflex activity depends on the status of the alpha motor neurons, the muscle spindles and their afferent fibers, and the gamma neurons whose axons terminate on intrafusal muscle fibers within the spindles. Rapid distension of the tendon stretches the spindle and activates its fibers. Afferent projections form these fiber synapses with the alpha motor neurons, which in turn send impulses to the skeletal muscles resulting in the familiar brief muscle contraction or monophasic stretch reflex.

The reflex is usually named after the muscle being tested. Common stretch reflexes include the quadriceps or patellar reflex involving the L2 to L4 spinal levels, medial hamstring reflex at the L5 level, and Achilles reflex involving the S1 level ( Fig. 7.7 ). A 5-point grading system recommended by the National Institute of Neurological Disorders and Stroke is the most commonly used scale ( Table 7.5 ). Eliciting reflexes may be difficult in the patient who is unable to relax. In 1885, Jendrassik described a technique to elicit reflexes by having the patient “hook together the flexed fingers of his right and left hands and pull them apart as strongly as possible” while the clinician taps on the tendon; this enhances the reflexes of patients.

A, Medial hamstring reflex. B, Prone technique for eliciting Achilles reflex.

Absent or exaggerated reflexes by themselves do not signify neurologic disease. In older adults, up to 50% without neurologic disease lack an Achilles reflex bilaterally. Small percentages (3% to 5%) of normal individuals have generalized hyperreflexia.

Absent or exaggerated reflex is significant only when it is associated with one of the following clinical settings:

• 1.
  

  The absent reflex is associated with other findings of lower motor neuron disease.

  
  
• 2.
  

  The exaggerated reflex is associated with other findings of upper motor neuron disease.

  
  
• 3.
  

  The reflex amplitude is asymmetric.

  
  
• 4.
  

  The reflex is unusually brisk compared with reflexes from a higher spinal level.

Straight-Leg Raise Test (Video 7-5 )

Lasègue’s sign, or straight-leg raise (SLR) test, was initially described by J. J. Frost, a student of Charles Lasègue in 1881, who memorialized his mentor through the naming of this test. In the described test, pain was induced in the distribution of the sciatic nerve upon lifting the leg while maintaining it extended via pressure on the knee. Frost suspected that the activation of pain during this maneuver was the result of pressure from the hamstring on the nerve. Lazarevic described this test in 1880, 1 year earlier than Frost, after he observed six patients to have increased pain during stretching of the sciatic nerve.

Lazarevic described a three-step approach to the test :

In the first step, the patient was asked to flex forward, maintaining his knees straight. In step 2, the patient was asked to lie supine and his trunk was slowly brought into flexion, maintaining his knees extended. In step 3, the supine patient had his leg raised with the knee extended. Elevation of the leg was stopped when the patient began to feel pain, and the angle of elevation and amount of pelvic movement was recorded. The patient was then asked to indicate the distribution of pain. All three maneuvers were noted to reproduce discomfort in the sciatic nerve distribution.

In 1884, Lucien de Beurmann concluded that during the lifting of a stretched leg, pain is evoked by stretching of the nerve rather than from the compression of the muscle. Inman and Saunders noted a 2- to 7-mm distal migration of the spinal nerve roots during performance of straight-leg raising. Falconer and coworkers described a 2- to 6-mm downward migration of the nerve roots through their respective foramen during the test. Goddard and Reid noted the L5 nerve root to move 3 mm and the S1 nerve root to move 4 to 5 mm during performance of SLR. In a recent controlled in vivo radiologic study, Rade and colleagues scanned 16 asymptomatic subjects with a 1.5 T magnetic resonance imaging (MRI) scanner; the displacement of the medullar cone during the SLR was quantified and noted to displace caudally in the spinal canal by 2.31 ± 1.2 mm with right SLR and 2.35 ± 1.2 mm with left SLR, which was speculated to be directly proportional to the sliding of the L5 and S1 nerve roots.

The classic SLR test is considered positive when the supine leg is elevated to between 30 and 70 degrees and pain is reproduced down to the posterior thigh below the knee. Pain below 30 degrees is not considered to be related to nerve root irritation. Kosteljanetz and others noted prolapsed discs in 45 of 52 individuals diagnosed during surgery with a positive SLR on physical examination. In addition, no “typical” Lasègue’s sign with pain into the leg was noted beyond 70 degrees of leg elevation. SLRs with pain induced beyond 70 degrees of leg elevation is not believed to be due to nerve root tension. Rather, it is thought likely to be related to tightness within the hamstrings or gluteal muscles ( Fig. 7.8 ).

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