A nonsurgical treatment approach for patients with lumbar spinal stenosis.

Key Words: Rehabilitation, Spinal stenosis, Treadmill, Unloading.

Lumbar spinal stenosis (LSS) is defined as a narrowing of the spinal canal, nerve root canals, or vertebral foramina.[1] It is the most common preoperative diagnosis in persons over age 65 years who are undergoing lumbar spinal surgery.[2] Annually, in the United States, approximately 1 in 1,000 individuals over the age of 65 years undergoes a laminectomy for lumbar spinal stenosis, with costs estimated to be $1 billion.[3] Lumbar spinal stenosis is congenital or acquired.[1,4-6] Acquired forms of LSS are further classified as degenerative, spondylolisthetic, iatrogenic (post-surgical), posttraumatic, or combined.[1,5,7] Lumbar spinal stenosis also is classified as central, lateral, or combined. Central stenosis involves narrowing of the central spinal canal. Lateral stenosis affects the nerve root canal.[1,8]

Degenerative changes are the most common cause of LSS.[6,9] The degenerative changes leading to LSS are believed to be progressive, but the rate of deterioration is not considered to be linear and factors influencing the progression of changes have not been identified.[10,11] Nevertheless, many researchers believe that the prognosis for persons with LSS is poor and that surgical intervention is the most viable treatment option.[12,13] Indications for surgery for LSS are poorly defined, and controversy exists as to the optimal surgical procedures.[2,14-16] Surgery for LSS is associated with increased rates of mortality and morbidity,[17] and reoperation rates are reported to be as high as 21%.[2,15] A trial of nonsurgical therapy, including anti-inflammatory medications, corsets, epidural steroid injections, and physical therapy, is frequently recommended,[5,18-20] but specific conservative treatment regimens have not been defined.

Patients with LSS are most often at least 50 years of age with prolonged histories of low back pain and recent onset of unilateral or bilateral lower-extremity pain.[2,5,8,21] The symptoms, which are posture-dependent, are worsened with extension of the lumbar spine or weight-bearing postures of the spine and decreased with flexion or non-weight-bearing postures of the spine.[4,22,23] Neurological deficits are reported in about 50% of cases.[2,8] Acute cauda equine syndrome, although rare, has been reported.[2,8] Neurogenic claudication, defined as pain, paresthesia, and cramping of the lower extremities brought on by walking and relieved by sitting,[24] frequently accompanies LSS.[2,5,8] Progressive reduction of walking tolerance due to neurogenic claudication is common and is considered by some authors[5,25] to be an indication for surgical intervention.

Acquired LSS has been attributed to structural narrowing of the spinal canal by one or more of the following conditions: facet-joint arthrosis and hypertrophy,[9,22,26] thickening and bulging of the ligamentum flavum,[4,27,28] outward bulging of the intervertebral disk,[29] and anterior displacement of the superior articulating process of the vertebral body due to lumbar spinal instability.[4,28,29] Symptomatic LSS cannot be attributed solely to structural narrowing of the canal dimensions, however, as evidenced by the high prevalence of narrowing seen on magnetic resonance imaging (MRI) scans or myelograms in individuals who have no symptoms[30,31] and by the poor correlations found between the severity of findings from imaging studies and the symptoms of patients with symptomatic LSS.[8,21] In addition to structural encroachment with movement (extension), narrowing of the spinal canal can occur. The cross-sectional area of the lumbar spinal canal and lateral recesses has been shown to increase with spinal flexion and to decrease with extension.[4,28,32] In a normal spine, the cross-sectional area is reduced by 9% during extension, but the reduction increases to 67% with severe stenosis.[32] Penning[4] has described the interplay between structural narrowing and changes that occur with movement as the "rule of progressive narrowing," which states that the more the canal is structurally narrowed by a stenosing process, the more it will be narrowed with extension. In addition to lumbar extension, loading of the spine through the compressive force associated with a weight-bearing posture reduces the cross-sectional area of the spinal canal.[4,28] Schonstrom et al[28] found that compressive loading had a slightly greater effect on decreasing the dimensions of the canal than did lumbar extension.

The movement-associated component of the stenosing process makes the symptoms of LSS posture-dependent, worsening with extension or compressive loading of the spine and improving with flexion or unloading of the spine.[4,22,23] Ambulation is an activity that involves both extension and compressive loading of the spine, and therefore it is frequently limited in patients with symptomatic LSS.[2,5,9] Limitations in ambulation can come from a variety of sources such as vascular claudication, lumbar disk herniation, or degenerative changes in the joints of the lower extremities. The differential diagnosis of whether the limitation is due to LSS can be difficult. A two-stage treadmill test, making use of the posture-dependent nature of the symptoms of LSS, is currently being investigated as a clinical tool to assist in the differential diagnosis of limited ambulation.[33] Walking on an inclined treadmill increases spinal flexion, and this increased spinal flexion should improve ambulation in persons with LSS.[33] Theoretically, the flexion should not improve the ambulation of patients with limitations due to causes other than LSS. Preliminary findings with the use of a two-stage treadmill test appear to support the hypothesis that patients with LSS will demonstrate one or all of the following findings: increased ambulation time on inclined treadmill tests, earlier onset of pain during the level ambulation stage versus the inclined ambulation stage, or prolonged recovery time after the level ambulation stage.[33]

The use of harness-supported treadmill ambulation, or unloading, has been advocated for use in patients with amputations,[34,35] foot injuries,[36] and herniated lumbar intervertebral disks,[37,38] but its application for patients with LSS has not been reported. Unloading involves the use of a traction harness and the application of a vertical traction force while the patient ambulates on a treadmill. The traction force is intended to reduce the gravitational force on the spine. This reduction in the compressive loading on the spine during ambulation may be useful in the treatment of patients with LSS.

A variety of measurements can be used to assess treatment of patients with low back pain, including those with LSS. In a recent meta-analysis of studies of the surgical treatment of patients with LSS, there was criticism of authors for generalizing outcomes into broad categories instead of looking at outcomes at multiple levels of a disability model.[2] Nagi[39] presented a scheme that defines four dimensions of disablement that need to be considered in a comprehensive assessment of treatment outcomes: (1) active pathology, or interruption of normal processes and the organism's inability to regain a normal state, (2) impairment, or loss or abnormality of an anatomical, physiological, or emotional nature, (3) functional limitation, or restriction of performance of the individual, and (4) disability, or restriction of an individual's ability to perform socially defined roles.

The purpose of our case report is to describe an approach to the physical therapy evaluation of two patients diagnosed with LSS. A treatment approach based on the evaluation results of each patient is described, including the use of harness-supported treadmill ambulation. Outcome measurements for different levels associated with the disablement process are presented for each patient.

Case Description

Patients

The two patients selected for this case report had pathology and clinical presentations consistent with a diagnosis of LSS. Patient data are summarized in Table 1. Patient 1 was a 58-year-old woman with a 10-year history of low back pain and a 6-month history of right leg pain exacerbated by walking. Onset of the lower-extremity symptoms was gradual; no spinal trauma was reported. Anteroposterior and lateral radiographs and MRI scans obtained 2 months prior to physical therapy showed degenerative changes of the facets and intervertebral disks at the L3-4 and L5-S1 levels (Fig. 1) in addition to multilevel central stenosis.

Table 1. Patient Characteristics

                                Patient 1

Age (Y)                         58
Gender                          Female
Height (cm)                     152
Weight (kg)                     55
Medical history                 9 y after kidney transplantation
                                Non-insulin-dependent diabetes
                                 mellitus
                                2 y after left tibial plateau
                                 fracture
                                Hypertension
Medication                      Immunosuppressive medication,
                                 prednisone, Tylenol[R] with
                                 codeine(a)
Diagnostic imaging results(c)   Right-facet osteoarthritis at L3-4,
                                 L4-5, L5-51
                                Degenerative disk disease
                                 at L3-4, L5-S1
                                Mild central stenosis at L2-3
                                Moderate central stenosis at
                                 L34, L4-5
                                Central disk herniations at
                                 L3-4, L5-S1

                                Patient 2

Age (Y)                         76
Gender  Female                  Male
Height (cm)                     190
Weight (kg)                     99
Medical history                 Left-knee osteoarthritis
                                Hypertension

Medication                      Altace[R](b)

Diagnostic imaging results(c)   Mild central stenosis at L2-3
                                Severe central stenosis at
                                 L34, L4-5
                                Right lateral stenosis at L4-5

(a) McNeil Pharmaceutical, 1000 US Rte 202, PO Box 300, Raritan, NJ 08869.

(b) Hoechst-Roussel Pharmaceuticals Inc, Rte 202-206, PO Box 2500, Somerville, NJ 08876.

(c) Patient 1: radiographs and magnetic resonance imaging scans patient 2: radiographs and computed tomography scans.

[Figure 1 ILLUSTRATION OMITTED]

Patient 2 was a 76-year-old man with a 25-year history of low back pain and a 7-month history of left anterior leg pain exacerbated by walking. No spinal trauma was reported. This patient had undergone anteroposterior and lateral radiography and a computed tomography scan 2 weeks prior to referral for physical therapy that showed multilevel central stenosis and lateral stenosis of the right L4-5 intervertebral foremen (Fig. 2).

[Figure 2 ILLUSTRATION OMITTED]

Initial Physical Therapy Evaluation

During the initial physical therapy evaluation, the patients completed medical history questionnaires, visual analog pain scales, the Modified Oswestry Low Back Pain Questionnaire,[40] and the Roland-Morris Disability Questionnaire.[41] The Modified Oswestry Low Back Pain Questionnaire[40] covers 10 areas of daily living and expresses the degree of disability as a percentage. The Roland-Morris Disability Questionnaire[41] contains 24 items selected from the 136-item Sickness Impact Profile[42] and reports a score from 0 to 24, with a score of 24 reflecting the greatest limitation. Scores on both questionnaires have shown Pearson correlation coefficients between .76 and .99, and the construct validity of the two questionnaires is supported through correlations with variables such as pain, spinal mobility, and psychological and patient satisfaction measures.[40,41,43,44] Studies of the reliability and validity of existing scales have been conducted on patients with low back pain without regard to diagnosis. The performance of these instruments in a subgroup of patients with LSS is not known. For the visual analog pain scale, we asked the patients to rate their level of pain on a scale of 0 to 10, with 0 representing no pain and 10 representing extreme pain. Visual analog pain scales have been shown to yield reliable measurements.[45]

After the patients completed the questionnaires and visual analog pain scale, a physical examination was performed. In patients with symptoms extending below the knee, we conduct a neurological examination, which includes the measurement of lower-extremity reflexes, sensation and muscle force production testing, and assessment of straight leg raise. The Achilles and patellar tendon reflexes are tested. Manual muscle testing of the lower extremities is performed to identify any myotomal pattern of weakness. Sensation is assessed by light touch and pinprick over each dermatome of the lower extremity. We consider the straight leg raise test to be positive for irritation of the sciatic nerve when motion is limited to less than 70 degrees and produces radicular pain.[46]

Assessment of the bony landmarks of the pelvis was then done while the patients were in a standing position. We palpated the posterior superior iliac spines (PSISs), anterior superior iliac spines (ASISs), and iliac crests bilaterally and compared the relative heights of the left and right landmarks. Consistently higher landmarks on one side may indicate a leg-length discrepancy,[47] whereas an inconsistent pattern (eg, a high right ASIS with a high left PSIS) may indicate another condition, one probably associated with the sacroiliac region.[48] If we suspect a leg-length discrepancy, we palpate the bony landmarks with the patient in a sitting position. In the presence of a leg-length discrepancy, we believe that the landmarks should appear to be level with the patient in a sitting position. If a sacroiliac joint-related problem is suspected, tests are performed as described elsewhere.[48] When a composite of several positive tests is used to define the presence of sacroiliac joint dysfunction, acceptable intertester reliability has been shown.[49] We tested active spinal range of motion with the patients in a standing position. The patients bent to the left and right sides, flexed, and extended. Measurements were taken with a gravity goniometer,(*) which has been shown to yield reliable measurements of spinal range of motion.[50] We recorded the patients' reports of changes in symptoms with movement as well as the range of motion. In persons with low back and lower-extremity pain, according to McKenzie,[51] symptoms may (1) peripheralize (paresthesia is produced or the pain or paresthesia moves distally from the lumbar spine), (2) centralize (paresthesia or pain is eliminated or moves from the periphery toward the lumbar spine), or (3) be unchanged with movements.

The symptoms of a degenerative hip joint and LSS are similar, and the two conditions can occur simultaneously.[52] We believed that an examination of the hip was therefore necessary to rule out potential involvement of the hip joint in these two patients. The examination consisted of the Patrick and scour tests.[52] The Patrick test is performed with the patient positioned supine with the hips and knees extended. The knee of the tested extremity is placed over the opposite knee, bringing the tested hip into flexion, abduction, and lateral (external) rotation. Pressure is applied to the medial aspect of the knee on the tested side. Anterior groin or thigh pain is considered a positive finding for hip joint dysfunction. A loss of motion of one hip joint relative to the opposite side has been correlated with radiographic evidence of osteoarthritis of the hip joint.[54] Production of pain in the low back or buttock is indicative of lumbar spine or sacroiliac joint involvement.[55] The scour test is performed by compressing the hip joint while moving from the position of flexion, medial (internal) rotation, and adduction into extension, lateral rotation, and abduction. Production of pain or crepitation is a positive test for hip joint dysfunction.[53] If a positive test for hip joint dysfunction is found, a more specific evaluation of the hip joint is indicated to determine the nature of the dysfunction.

In patients with chronic low back pain, such as those with LSS, we include an examination for signs of physical impairments such as weakness or lack of flexibility.[48] Manual muscle testing and flexibility testing of the lower extremities were performed as described by Kendall and McCreary.[56], In patients with chronic low back pain, the gluteal muscles tend to become weak, whereas the hip flexors and hamstring muscles may become shortened.[57,58] Assessment of these muscle groups is therefore appropriate in patients with chronic low back pain. Flexibility of the one- and two-joint hip flexors was assessed with the Thomas test.[56] We consider one-joint hip flexors to be shortened when the tested hip is unable to fully extend while the pelvis maintains a posteriorly tilted position.[56] We consider two-joint hip flexors to be shortened if the knee is unable to reach 80 degrees of flexion without increasing hip flexion.[56] Hamstring muscle length was assessed by measuring the angle of hip flexion obtained during a straight-leg-raising test with the opposite leg extended and the pelvis posteriorly tilted. Kendall and McCreary[56] defined a positive test as less than 80 degrees of hip flexion. Gluteus maximus muscle force production was determined by resisting hip extension with the patient positioned prone and the knee fully flexed. The gluteus medius muscle was tested with the patient positioned side lying and the hip in abduction with slight hip extension and lateral rotation. The motion of abduction is resisted.[56]

We have been investigating the ability of a two-stage treadmill test to discriminate between patients with and without LSS.[33] The two patients described in this case report agreed to participate in that study. This test is performed by having the patient ambulate on a level treadmill and a treadmill with a 15-degree incline. As part of the research protocol, the order of incline is determined randomly. For patients undergoing repeat testing following intervention, the same order of testing is used for the follow-up test.

The patients were asked to walk at a comfortable pace without using handrails. The walking time until the symptoms of low back or lower-extremity pain increased over the level recorded before the test began, and the maximal walking time, limited by either fatigue or symptoms, were recorded. Patients walked for a maximum of 15 minutes then sat, and the time required for symptoms to return to the pretreadmill walking level was recorded. The patients rested for a total of 15 minutes, and the test was repeated using the second treadmill position.

Outcome Measures

Measures of treatment outcomes for these two patients included the visual analog scale, the Modified Oswestry Low Back Pain Questionnaire,[40] the Roland-Morris Disability Questionnaire,[41] impairments identified at the initial evaluation, and the two-stage treadmill test. All outcome measures were assessed at the initial evaluation and at completion of physical therapy. Except for the measure of impairments, the measures were assessed again 4 weeks later.

Findings of the Initial Physical Therapy Evaluation

The results of the self-report questionnaires administered at the initial evaluation are presented in Table 2, and the results of the physical examination are shown in Table 3. Patient 1 had a leg-length discrepancy, with a long right leg. Both patients exhibited a peripheralization of symptoms with lumbar extension, as expected in patients with LSS. Patient 1 had positive findings on neurological assessment in the form of reflex, sensory, and motor changes, as well as a positive straight-leg-raising test. The results of the two-stage treadmill test for patient 1 (Tab. 4) showed a longer walking time on the inclined treadmill, an earlier onset of symptoms on the level treadmill, and a longer recovery after level treadmill ambulation. The two-stage treadmill test results for patient 2 showed an earlier onset of symptoms and a longer recovery time with level treadmill ambulation than with inclined treadmill ambulation.

Table 2. Results of Self-Report Measures Administered at Initial Evaluation, After 6 Weeks of Physical Therapy, and at 4-Week Follow-up

                                  Patient 1
                                  Initial        After 6 Weeks of
Measure                           Evaluation     Physical Therapy
Modified Low Back Pain Oswestry
  Questionnaire[40] (%)           48             16
Roland-Morris Disability
Questionnaire[4]                  17              2
Visual analog pain scale           6/10           1/10

                                  Patient 1
                                  4-Week
Measure                           Follow-up
Modified Low Back Pain Oswestry
  Questionnaire[40] (%)           12
Roland-Morris Disability
Questionnaire[4]                   3
Visual analog pain scale           1/10

                                  Patient 2
                                  Initial        After 6 Weeks of
Measure                           Evaluation     Physical Therapy
Modified Low Back Pain Oswestry
  Questionnaire[40] (%)           53             0
Roland-Morris Disability
Questionnaire[4]                  19             1
Visual analog pain scale           5/10          0/10

                                  Patient 2
                                  4-Week
Measure                           Follow-up
Modified Low Back Pain Oswestry
  Questionnaire[40] (%)           0
Roland-Morris Disability
Questionnaire[4]                  1
Visual analog pain scale          0/10

[TABULAR DATA 3 NOT REPRODUCIBLE IN ASCII]

Table 4. Results of Two-Stage Treadmill Test for Patient 1 of Initial Evaluation, After 6 Weeks of Physical Therapy, and at 4-Week Follow-up

                         Inclined Treadmill
                                            After 6 Weeks
                         Initial            of Physical
Measure                  Evaluation         Therapy
Walking speed (mph)      0.7                0.8
Time to increase in      4 1/4              No increase
  symptoms (min)                              noted
Maximum walking time     7 1/6              15
  (min)
Symptoms at              Low back pain,     Fatigue
  completion               fatigue
Recovery time (min)      3 1/3              N/A(a)

                         Inclined Treadmill
                         4-Week
Measure                  Follow-up
Walking speed (mph)      0.8
Time to increase in      No increase
  symptoms (min)           noted
Maximum walking time     15
  (min)
Symptoms at              Fatigue
  completion
Recovery time (min)      N/A

                         Level Treadmill
                                            After 6 Weeks
                         Initial            of Physical
Measure                  Evaluation         Therapy
Walking speed (mph)      0.7                0.8
Time to increase in      2 1/2              No increase
  symptoms (min)                              noted
Maximum walking time     4 1/2              15
  (min)
Symptoms at              Low back pain,     None noted
  completion               left calf pain
Recovery time (min)      4 1/6              N/A

                         Level Treadmill
                         4-Week
Measure                  Follow-up
Walking speed (mph)      0.8
Time to increase in      No increase
  symptoms (min)
Maximum walking time     15
  (min)
Symptoms at              None noted
  completion
Recovery time (min)      N/A
  noted

(a) N/A=not assessed.

Treatment Plan

Both patients received physical therapy for LSS over a 6-week period. Patient 1 was seen for eight visits and patient 2 was seen for 11 visits during that period. The treatment approach had two components: an exercise program and a program of harness-supported treadmill. In addition, patient 1 received a 1.27-cm (0.5-in) heel lift in the left shoe to correct a leg-length discrepancy of 1.27 cm. The exercise program was designed to address impairments identified at the initial evaluation. The impairments to be addressed were decreased lower-extremity muscle force production, flexibility, and peripheralization of symptoms with lumbar extension. Spinal flexion increases the spinal canal dimensions.[4,28,32] We believed, therefore, that flexion exercises may help to decrease symptoms.

Flexion exercises including posterior pelvic tilts, quadruped spinal flexion, and single-knee-to-chest exercises were performed by patient 1. Patient 2 performed quadruped spinal flexion. Patient 2 tolerated treadmill exercise better than did patient 1 initially. Treatment for patient 2, therefore, was focused more on treadmill training than on flexion exercises. All flexion exercises were performed in gravity-eliminated postures to avoid the compressive loading associated with weight bearing that reduces the dimensions of the spinal canal.[28] Both patients performed flexion exercises three to four times per day, performing 10 repetitions of each exercise.

Flexibility deficits were addressed with hamstring muscle stretching performed by extending the knee while positioned supine with the hip flexed to 90 degrees. This position was held for 30 seconds and repeated five times. Hip flexor stretching was performed by maintaining a posterior pelvic tilt while in a half-kneeling posture. The muscle force production deficits identified in patient 1 were addressed with lower-extremity strengthening exercises focusing on the gluteus medius muscle and consisting of hip abduction in a standing position with the pelvis maintained in the horizontal plane, progressing to single-leg standing and then to lateral step-ups while maintaining a horizontal pelvis. Both patients performed mini-squats for general lower-extremity strengthening. Mini-squats were formed in the standing position by slowly flexing the knees to approximately 45 degrees and then returning to the extended position. Patient 2 was progressed to straight leg raises in flexion, extension, abduction, and adduction and terminal knee extension exercises to address the quadriceps femoris muscle weakness.

Flexion exercises were performed as a single set of 10 repetitions; flexibility exercises were performed as a single set of 5 repetitions consisting of 30-second stretches; and strengthening exercises were performed in sets of 10 repetitions, beginning with a single set and progressing to three sets, as tolerated by the patient. Each physical therapy session lasted approximately 1 hour. Both patients reported that they performed their exercises once or twice daily at home.

Each patient's initial performance on the two-stage treadmill test showed limitations in the ability to ambulate on level surfaces without symptoms of low back or lower-extremity pain. These limitations were addressed by using harness-supported treadmill ambulation in which a vertical traction force can be applied to reduce the compressive loading on the spine and allow for pain-free gait training. This ambulation can be performed in a pool using the buoyancy of the water, as was initially done for patient 1, or using a treadmill and traction harness* to provide a traction force to partially unload the spine of the compressive forces associated with weight-bearing postures (Fig. 3). Sufficient traction was applied to completely relieve the patient's symptoms of low back and lower-extremity pain during ambulation. The progression of harness-supported treadmill ambulation for both patients is shown in Table 5. Patient 1's ambulation was begun in the pool because this is considered to be a less demanding activity. This patient was soon able to progress to harness-supported treadmill ambulation.

Table 5. Progression of Harness-Supported Treadmill Ambulation During Physical Therapy Sessions

Session
No.      Patient 1                 Patient 2

1        Pool walking X 10 min     Treadmill unloading: 2.0
                                    mph
                                   22 lb of traction
                                   30 min of ambulation

2        Pool walking X 15 min     Treadmill unloading: 2.0
                                    mph
                                   22 lb of traction
                                   30 min of ambulation

3        Treadmill unloading: 0.7  Treadmill unloading: 2.0
          mph                       mph
         40 lb of traction         22 lb of traction
         Two sets of 10 min        30 min of ambulation
          of ambulation

4        Treadmill unloading :     Treadmill unloading: 2.0
          0.8 mph                   mph
         37 lb of traction         20 lb of traction
         Two sets of 15  min       35 min of ambulation
          of ambulation

5        Treadmill unloading:      Treadmill unloading: 2.0
         No gait training                 mph
           performed               20 lb of traction
                                   35 min of ambulation

6        Treadmill unloading:      Treadmill unloading: 2.0
          0.8 mph                      mph
         24 lb  of traction        15 lb of traction
         Two sets of 20 min of     40 min of ambulation
          ambulation

7        Treadmill unloading: 0.8  Treadmill unloading: 2.0
          mph                        mph
         18 lb of traction         15 lb of traction
         Two sets of 20 min of     45 min of ambulation
           ambulation

8        Treadmill: 0.8 mph        Treadmill: 2.0 mph
         No traction used          No traction used
         Two sets of 15 min        30 min of ambulation
           ambulation

9        N/A(a)                    Treadmill 2.5 mph
                                   No traction used
                                   30 min of ambulation

10       N/A                       Treadmill: 2.5 mph
                                   No traction used
                                   30 min of ambulation

11       N/A                       Treadmill: 2.5 mph
                                   No traction used
                                   30 min of ambulation

(a) N/A=not assessed

[Figure 3 ILLUSTRATION OMITTED]

Treatment Outcome

At the completion of 6 weeks of treatment (both patients were referred for 6 weeks of treatment and then returned to their physician), the patients' impairments were reassessed (Tab. 3) and the self-report measures (Tab. 2) and the two-stage treadmill test (Tabs. 4, 6) were repeated. Improvements were noted in some of the impairment measures. Both patients showed improvements in lumbar range of motion. Patient 1 showed improvements in neurological status and sensation as well as improvement in performance of the straight-leg-raising test. Improvements in muscle force production were noted, particularly in the gluteus medius muscle of patient 1 and the quadriceps femoris muscle of patient 2. It must be remembered that the reliability of grading manual muscle testing is known to be poor,[59] and the improvements noted could represent measurement error. Substantial improvements were found on the self-report outcome measures (Tab. 2) and the two-stage treadmill test (Tabs. 4, 6). Both patients were able to ambulate the full 15 minutes during the 6-week reassessment. Both patients were instructed to continue their home exercise program daily after discharge from physical therapy and to perform at least 15 to 20 minutes of symptom-free walking daily. If symptoms occurred, the patients were instructed to stop walking and sit until the symptoms diminished.

Table 6. Results of Two-Stage Treadmill Test for Patient 2 at Initial Evaluation, After 6 Weeks of Physical Therapy, and at 4-Week Follow-up

                                 Inclined Treadmill
                                                      After 6 Weeks
                                  Initial             of Physical
Measure                           Evaluation          Therapy

Walking speed (mph)               1.5                 2.5
Time to increase in symptoms      2 1/4               No increase
  (min)         noted                                   noted
Maximum walking time (min)        5 1/6               15
Symptoms at completion            Left anterior leg   None noted
                                    pain
Recovery time (min)               4                   N/A(a)

                                  Inclined Treadmill
                                  4-Week
Measure                           Follow-up

Walking speed (mph)               2.5
Time to increase in symptoms      No increase
  (min)         noted               noted
Maximum walking time (min)        15
Symptoms at completion            None noted

Recovery time (min)               N/A

                                  Level Treadmill
                                                      After 6 Weeks
                                  Initial             of Physical
Measure                           Evaluation          Therapy

Walking speed (mph)               1.5                 2.5
Time to increase in symptoms      1 5/6               No increase
  (min)         noted                                   noted
Maximum walking time (min)        5 1/4               15
Symptoms at completion            Left anterior leg   None noted
                                    pain
Recovery time (min)               4 1/3               N/A

                                  Level Treadmill
                                  4-Week
Measure                           Follow-up

Walking speed (mph)               2.5
Time to increase in symptoms      No increase
  (min)                             noted
Maximum walking time (min)        15
Symptoms at completion            None noted

Recovery time (min)               N/A

(a) N/A=not assessed.

Both patients returned for a follow-up assessment 4 weeks after discharge from physical therapy. The self-report measures (Tab. 2) and the two-stage treadmill test (Tabs. 4, 6) were readministered. The results indicated that the improvements in limitations and disability noted at the conclusion of physical therapy were maintained over a 4-week period following discharge. Both patients reported doing their home exercise programs, and neither patient reported using any pain medication following discharge.

Discussion

The structural component of LSS is identified by imaging techniques such as radiography, MRI, and computed tomography. Treatment of patients with LSS has focused on addressing the structural component through surgical procedures such decompression-laminectomy and lumbar fusion.[6,12,25] The movement-associated component of LSS results from the changes in the spinal canal dimensions with lumbar motion or with compressive loading.[4,23,28,32] Failure to consider the movement-associated component of LSS may partially explain the relatively high incidence of structural changes on imaging studies of individuals without symptoms of LSS[30,31] and the poor correlation between the degree of structural changes seen on imaging and the severity of symptoms.[8,21] Treatment of the movement-associated component through appropriate exercise programs has received little attention.

We believe that findings from the patient's history and clinical examination must correlate with the structural findings before a diagnosis of LSS can be made.[8,21,52] Physical therapy, in our opinion, also must be based on the patient's signs and symptoms and not on a structural diagnosis, even when such a diagnosis exists.[48] In addition, the severity of the structural pathology seen on diagnostic imaging studies in patients with LSS has been shown to correlate poorly with the severity of symptoms and limitations.[8,21]

The patients in this case report had moderate to severe pathological changes (Figs. 1, 2), yet they responded positively to physical therapy. Both patients demonstrated peripheralization of symptoms with extension, and they reported claudication-like symptoms, which were confirmed by the two-stage treadmill test. The treadmill test also confirmed the posture-dependent nature of the patients' symptoms, with less severe symptoms noted during inclined walking with the spine in more flexion. Delitto et al[48] classified these signs and symptoms as a flexion syndrome, and they recommended the use of flexion exercises as treatment. We also use harness-supported treadmill ambulation for patients with leg pain brought on by walking and relieved with sitting. This type of ambulation provides a functional rehabilitation tool that addresses a common limitation for patients with LSS.[35,36] The amount of unloading force is monitored and progressed until unloading force is no longer required to relieve pain during ambulation, as was demonstrated by the patients in this case report.

We believe that a comprehensive assessment of patients with low back pain should include outcome measures that capture the multidimensional nature of pain and the degree of disablement due to low back pain.[60,61] fit For the patients we described, we assessed each dimension, with the exception of the active pathology. Measurements of spinal range of motion, neurological status, lower-extremity muscle force production, and flexibility were used as outcomes in the assessment of impairments. Limited ambulation is a frequent limitation among patients with LSS and was noted for both patients described in this case report. The use of a treadmill test to approximate ambulation tolerance has been recommended as an outcome measure for patients with spinal disorders.[62 63] The two-stage treadmill test, therefore, serves as both a clinical diagnostic tool and an outcome measure for these patients. Disability was assessed by the Modified Oswestry and Roland-Morris questionnaires. For the patients described in this case report, improvements were found at the completion of treatment, as indicated by the results from both disability questionnaires (Tab. 2). These improvements coincided with improvements in the total walking time during the treadmill test (Tabs. 4, 6). Both patients were able to more than double their total walking time.

The purpose of our case report was to describe an approach to the evaluation, treatment, and outcome assessment for patients with LSS. No experimental evidence is offered. The tendency for low back pain to improve over time must be considered. In addition, the patients were treated with a program of treadmill ambulation, and the improvements noted on the two-stage treadmill test could represent task-specific improvements. In our view, experimental studies can be performed only after an approach to evaluation, treatment, and outcome assessment has been defined for the population being studied. This case report of two patients with short-term follow-up needs to be followed by reports describing larger series of patients with LSS treated with this approach with longer follow-up periods. If the treatment approach we are recommending produces favorable long-term outcomes in larger series of patients, then a randomized clinical trial would be warranted to compare this approach with the present "standard of care," which consists of the use of medications or nonspecific exercises.[15] Only a randomized clinical trial could produce experimental evidence for the efficacy of the treatment approach we suggest.

Acknowledgments

We thank the members of the faculty of the Department of Physical Therapy, University of Pittsburgh, including Jennifer S Brach, PT, Jay Irrgang, PT, ATC, Dina L Jones, PT, and Jessie M VanSwearingen, PhD, PT, for their thoughtful insights regarding the manuscript.

(*) Vigor Equipment Inc, 4915 Advance Way, Stevensville, MI 49127.

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JM Fritz, PT, ATC, is Doctoral Student, Department of Physical Therapy, School of Health and Rehabilitation Sciences, University of Pittsburgh, 6035 Forbes Tower, Pittsburgh, Pa 15260 (USA) ([e-mail]). Address all correspondence to Ms Fritz.

RE Erhard, DC, PT, is Assistant Professor, Department of Physical Therapy, School of Health and Rehabilitation Sciences, University of Pittsburgh, and Director of Physical Therapy and Chiropractic Services, Comprehensive Spine Center, University of Pittsburgh Medical Center, Pittsburgh, Pa.

M Vignovic, PT, is Clinical Assistant Professor, Department of Physical Therapy, School of Health and Rehabilitation Sciences, University of Pittsburgh, and Musculoskeletal Team Leader, CORE Network, Pittsburgh, Pa.