Groin pain associated with lower lumbar disc herniation

STUDY DESIGN: Retrospective clinical and magnetic resonance imaging study of patients with groin pain associated with lower lumbar disc herniation. OBJECTIVES: To demonstrate the clinical features and magnetic resonance imaging findings of these patients. SUMMARY OF BACKGROUND DATA: Patients with lumbar disc herniation sometimes report groin pain. Little mention has been made, however, regarding the clinical features of groin pain stemmed from lower lumbar disc herniation until now, with only Murphey referring to groin pain in disc disease. METHODS: A total of 512 patients were diagnosed with singular lower lumbar disc herniation (L4-L5 and L5-S1) at Kakegawa City General Hospital between July 1990 and December 1993. Of these patients, 21 (4.1%) reported groin pain. The characteristic clinical features and magnetic resonance imaging findings of the 21 patients were investigated and compared with the features and findings of patients with no groin pain. RESULTS: Patients with groin pain had a higher mean age and lower rate of low back pain, and L4-L5 discs were more likely to be involved than L5-S1 discs. In their magnetic resonance images, herniation tended to be more central than in patients with no groin pain. CONCLUSIONS: Elderly patients with L4-L5 protruding herniation of the anulus fibrosus were most likely to experience groin pain. The sinuvertebral nerve that innervates the posterior anulus fibrosus, the posterior longitudinal ligament, and the dura was indicated as the afferent nerve of groin pain.     

Lumbar spine stenosis: a common cause of back and leg pain

Lumbar spine stenosis most commonly affects the middle-aged and elderly population. Entrapment of the cauda equina roots by hypertrophy of the osseous and soft tissue structures surrounding the lumbar spinal canal is often associated with incapacitating pain in the back and lower extremities, difficulty ambulating, leg paresthesias and weakness and, in severe cases, bowel or bladder disturbances. The characteristic syndrome associated with lumbar stenosis is termed neurogenic intermittent claudication. This condition must be differentiated from true claudication, which is caused by atherosclerosis of the pelvofemoral vessels. Although many conditions may be associated with lumbar canal stenosis, most cases are idiopathic. Imaging of the lumbar spine performed with computed tomography or magnetic resonance imaging often demonstrates narrowing of the lumbar canal with compression of the cauda equina nerve roots by thickened posterior vertebral elements, facet joints, marginal osteophytes or soft tissue structures such as the ligamentum flavum or herniated discs. Treatment for symptomatic lumbar stenosis is usually surgical decompression. Medical treatment alternatives, such as bed rest, pain management and physical therapy, should be reserved for use in debilitated patients or patients whose surgical risk is prohibitive as a result of concomitant medical conditions.     

The therapeutic impact of lumbar spine MRI on patients with low back and leg pain

The influence of lumbar spine magnetic resonance imaging (MRI) on the management of patients with low back and leg pain, with a clinical diagnosis of neural compression, has been investigated by a controlled prospective observational study. The clinical features of the patients at the time of request for MRI have been compared with the subsequent management in order to define the clinical indications for lumbar spine MRI. METHODS: Clinical history, physical examination findings and tests of functional and psychological disability were all recorded at the time of request for MRI. Following MRI, patients were assessed without knowledge of the MRI findings and a diagnosis and management plan recorded. Immediate access to the MRI report and hard copy films was then provided and a revised diagnosis and management plan made. The clinical features and MRI findings were compared with the subsequent management. RESULTS: Seventy-two patients were examined, 65 (90.3%) had leg pain as a predominant feature and abnormalities in neurological examination were found in 31 (43%). Twenty-three of 48 (47.9%) of patients with a pre MRI management plan of surgery were changed to conservative management following the MRI. The diagnosis altered in 50 % of cases with the largest change in diagnosis occurring in 13 patients where MRI did not confirm the clinical impression of nerve root compression. Seventeen patients with no abnormality of neurological testing were subsequently treated by surgery which included all 12 patients treated by spinal fusion. CONCLUSIONS: The major impact of MRI was to move patients towards conservative treatment. A variety of features in the history and physical examination as well as MRI findings are predictors for surgical treatment. The variety of diagnoses and surgical options available make it difficult to define clear clinical guidelines for the use of MRI.     

Predictive signs of discogenic lumbar pain on magnetic resonance imaging with discography correlation

STUDY DESIGN: The correlation between discogenic lumbar pain and disc morphology was investigated by using magnetic resonance imaging and discography. OBJECTIVES: To assess the various pathologic parameters seen on magnetic resonance imaging in patients with discogenic lumbar pain and to correlate them with observations on discography. SUMMARY OF BACKGROUND DATA: Although numerous previous studies on the subject have been performed, the correlations between various pathologic findings on magnetic resonance imaging and pain reproduction by provoked discography have not been explained fully. METHODS: One hundred and one lumbar discs in 39 patients were studied with magnetic resonance imaging and pain provocation discography. When pain reproduction under discography was concordant, various pathologic parameters on magnetic resonance imaging were analyzed by three statistical parameters to determine the associated magnetic resonance imaging findings. RESULTS: Radial tears commonly are demonstrated on magnetic resonance imaging in discs with concordant pain on discography. The presence of these tears is not a reliable predictor of a painful disc on discography. Although a high-intensity zone on T2-weighted images is a relatively reliable predictor of pain, the statistical values were lower than those in previous studies. Massive degeneration and severe disc height loss were rare in this population. These findings were good predictors of pain on disc injection. CONCLUSIONS: Although the lumbar intervertebral discs with posterior combined anular tears are likely to produce pain, the validity of these signs for predicting discogenic lumbar pain is limited.     

Aspiration of intraspinal synovial cyst: recurrence after temporal improvement

Intraspinal synovial cyst primarily occurs in the lumbar spine and may cause back pain and compression nerve disturbance. Percutaneous aspiration has been recommended as an alternative to surgery in three cases. We report on two patients who improved after aspiration of gelatinous material and steroid injection but whose cyst recurred within a short period of time. There are reportedly two types of synovial cyst: One contains serosanguineous fluid and the other gelatinous fluid. These two types are indistinguishable on computed tomography or magnetic resonance imaging. The results of all patients whose aspirated material was gelatinous were unsuccessful, including our cases. Thus, the outcome may depend on the pathology of the cyst.     

Dynamic effects on the lumbar spinal canal: axially loaded CT-myelography and MRI in patients with sciatica and/or neurogenic claudication

STUDY DESIGN: In patients with sciatica or neurogenic claudication, the structures in and adjacent to the lumbar spinal canal were observed by computed tomographic myelography or magnetic resonance imaging in psoas-relaxed position and during axial compression in slight extension of the lumbar spine. OBJECTIVES: To determine the mechanical effects on the lumbar spinal canal in a simulated upright position. SUMMARY OF BACKGROUND DATA: For years, functional myelographic investigation techniques were shown to be of value in the evaluation of suspected encroachment of the spinal canal. Since the advent of computed tomography and magnetic resonance imaging, there have been few clinical and experimental attempts that have imitated these techniques. The data indicate that the space within the canal is posture dependent. METHODS: Portable devices for axial loading of the lumbar spine in computed tomographic and magnetic resonance examinations were developed. Fifty patients (94 sites) were studied with computed tomographic myelography, and 34 patients (80 sites) with magnetic resonance in psoas-relaxed position followed by axial compression in slight extension. The dural sac cross-sectional area at L2 to S1, the deformation of the dural sac and the nerve roots, and the changes of the tissues surrounding the canal were observed. RESULTS: In 66 of the investigated 84 patients, there was a statistically significant reduction of the dural sac cross-sectional area in at least one site during axial compression in slight extension. Of the investigated patients, 29 passed the borderlines for relative (100 mm2) or absolute stenosis (75 mm2) in 40 sites. In 30 patients, there was deformation of the dural sac in 46 sites. In 11 of the patients investigated with magnetic resonance imaging, there was a narrowing of the lateral recess in 13 sites, during axial compression in slight extension. CONCLUSIONS: Axial loading of the lumbar spine in computed tomographic scanning and magnetic resonance imaging is recommended in patients with sciatica or neurogenic claudication when the dural sac cross-sectional area at any disc location is below 130 mm2 in conventional psoas-relaxed position and when there is a suspected narrowing of the dural sac or the nerve roots, especially in the ventrolateral part of the spinal canal in psoas-relaxed position. The diagnostic specificity of the spinal stenosis will increase considerably when the patient is subjected to an axial load.     

Pain drawing in the evaluation of low back pain

Pain drawings were obtained from three groups of patients: 51 with lumbar disc herniation; 55 with lumbar stenosis, and 42 with benign low back pain. On grid assessment, patients with disc herniation and stenosis who complained of radiating pain or intermittent claudication had a significantly larger number of grids for the extremities than those with benign low back pain. In studies of the relation between the characteristics of the pain drawing and the outcome of treatment, most patients with 19 grids or less, or a score of 3 points or less, had a satisfactory outcome. Those with more grids or a higher score tended to be unsatisfactory. Pain drawing permits differentiation of the three patterns of pain and is useful for predicting the outcome of treatment.     

The function of sensory nerve fibers in lumbar radiculopathy. Use of quantitative sensory testing in the exploration of different populations of nerve fibers and dermatomes

STUDY DESIGN: The function of sensory nerve fibers in patients with lumbar radiculopathy and in control individuals was evaluated using quantitative sensory testing. OBJECTIVES: To investigate the effect of lumbar nerve root compression on different populations of nerve fibers and to explore the function of sensory nerve fibers in neighboring nerve roots not involved in the mechanical compression. BACKGROUND DATA: Results from experimental and clinical studies indicate that chronic compression of lumbar nerve roots affects the large myelinated nerve fibers. The majority of nerve fibers involved in the sensation of pain, however, are small afferent nerve fibers. It is therefore of interest to study the effect of compression on large and small sensory afferent channels. Several authors have elucidated the biochemical interaction between disc tissue and nerve roots. Chemical substances in the epidural space can reach the nerve fibers in nerve roots at the same or neighboring lumbar segments. In this way, fibers not involved in the mechanical compression may be affected. METHODS: The small nerve fibers were studied using tests for thermal thresholds (thermotest), and the large myelinated fibers were studied by vibrametry. Forty-two patients were investigated in the symptomatic and the asymptomatic leg, and the results were compared with those of 21 healthy individuals. RESULTS: The thresholds of cold, warmth, and vibration were significantly increased in the dermatome of the compressed nerve root, indicating that large and small sensory nerve fibers were affected. Further, the thresholds were significantly increased in the neighboring dermatomes in the symptomatic and the asymptomatic leg. CONCLUSION: Large and small sensory afferent nerve fibers are affected in lumbar radiculopathy. The increase in sensation thresholds in the ipsilateral neighboring dermatome and in the dermatomes in the asymptomatic leg indicates that adjacent nerve roots are involved in the pathophysiology of sciatica in patients with lumbar disc herniation.     

Iliopsoas abscess accompanied by epidural abscess--a case report]

A 55-year-old man was admitted to a hospital with pain of the low back as well as the left leg, and fever. He was suspected of suffering from the lumbar disc herniation because of the presence of Lasegue's sign on the first physical examination. Abdominal computed tomography, however, revealed the swelling of the left iliopsoas muscle. Iliopsoas abscess accompanied epidural abscess was confirmed by subsequent magnetic resonance imaging (MRI). Antibiotic therapy was started for the successive 8 days. The fever resolved, but the pain persisted. The abscess extending from the iliopsoas muscle to the epidural space was still seen on the MRI 20 days after the completion of the antibiotic therapy, and he still complained of the pain of his low back and left leg. Therefore, we conducted epidural puncture under fluoroscopic guidance. Approximately 3 ml of pus was aspirated from the epidural space. Then, his complains decreased remarkably. Iliopsoas abscess should be taken into account in case of a patient with pain on the low back and leg and also inflammatory signs such as fever and leucocytosis.     

A long-term outcome analysis of 984 surgically treated herniated lumbar discs

This paper presents a long-term follow-up study of 984 patients operated on for a herniated lumbar disc between 1959 and 1991. It was possible to follow 98% of patients from the time of operation to the time of writing. The mean follow-up period was 10.8 years. The most common presenting complaint was back pain with sciatica in one leg; the most frequent neurological finding was impaired straight-leg raising. Myelography confirmed the diagnosis in 80% of patients, but more recently enhanced computerized tomography and magnetic resonance imaging have been the preferred studies. The operative procedure was either hemilaminectomy or laminectomy with x 3.5 magnification and fiberoptic lighting. Herniated lumbar discs involved L4-5 and L5-S1 with equal frequency (47%). The recurrence rate was 6%, one-third of which developed during the 1st year after operation. The complication rate was 4%; there were no intraoperative vascular or intestinal injuries. The Prolo Functional Economic Outcome Rating Scale was used to measure long-term outcome and the results were compared to those of Pappas, et al. Patients who did sedentary work and housewives had statistically higher total and economic Prolo scores (p < 0.01) than those who did strenuous work. The majority of patients with the "failed-back syndrome" had pending legal or Workers' Compensation claims, or were at psychological risk for surgery. In 89% of patients the outcome was good--defined as a Prolo score of 8 in 10%, 9 in 19%, and 10 in 60%.     

Spontaneous epidural hematoma as a cause of sciatic pain in a schoolboy

A previously healthy 13-year-old boy began to manifest radiating pain in his left leg after heavy physical exertion during judo training. He also had a sensation of numbness in his left buttock and leg. Initially, the patient was treated conservatively with a clinical diagnosis of disc herniation. However, following 3 months of conservative treatment, there was no relief of pain. Magnetic resonance imaging of the lumbar spine demonstrated an epidural mass causing compression of the dural sac at the L4-L5 disc level. During surgery, the L5 nerve root was found to be severely compressed in the spinal canal because of a chronic epidural hematoma. Following microsurgical removal of this hematoid mass, the patient had a good recovery. Spontaneous epidural hematomas in the lumbar region are rare, and only a few cases presenting with features simulating those caused by a disc herniation have been reported. Our patient represents the first such case described in a child.     

Patient characteristics associated with diagnostic imaging evaluation of persistent low back problems

STUDY DESIGN: Post hoc analysis of data from the National Low Back Pain Study, a prospective observational multicenter study of patients referred for the evaluation and treatment of persistent low back problems. OBJECTIVE: To identify patient characteristics associated with use of particular diagnostic imaging examinations in patients with persistent low back problems. SUMMARY OF BACKGROUND DATA: The Agency for Health Care Policy and Research clinical practice guidelines on low back problems suggest that the use of particular diagnostic imaging tests for a given patient should be based on specific characteristics of that patient. METHODS: Use of diagnostic imaging examinations in 2,374 patients with persistent low back problems who were enrolled in the National Low Back Pain Study from 1986 to 1991 was analyzed. Stepwise logistic regression was used to identify patient characteristics that distinguish between enrollees who underwent particular imaging studies. RESULTS: Characteristics that distinguished patients who had undergone magnetic resonance imaging from those who had received only lumbo-sacral spine radiographs included higher socioeconomic status, greater resource use in the preceding 12 months, more functional impairment, presence of sciatica, and presence of neurologic signs/symptoms suggestive of nerve root compromise. Suspected soft tissue involvement was characteristic of enrollees who had undergone magnetic resonance imaging, whereas suspected structural involvement characterized patients who received noncontrast computed tomography. Only nonclinical factors, such as higher annual household income, disability compensation, and male gender distinguished enrollees who had undergone both magnetic resonance imaging and computed tomography-myelography from those who received only computed tomography-myelography. CONCLUSION: Particular patient socioeconomic and clinical characteristics are associated with receipt of specific imaging studies in evaluation of persistent low back problems.     

An unusual cause of sciatica. A case report

STUDY DESIGN: This case report illustrates the need to be aware of extraspinal causes of sciatica. A patient with a strangulated sciatic hernia showed the clinical features of sciatic leg pain, intestinal obstruction, and a left gluteal abscess. OBJECTIVE: To highlight the need to examine the course of the sciatic nerve for local pathology when the cause of sciatica is not obvious. SUMMARY OF BACKGROUND DATA: Sciatic herniae are rare. The coexistence of sciatica and a gluteal abscess, caused by a strangulated sciatic hernia, does not appear to have been reported previously. METHODS: A 66-year-old woman with preexisting low back pain and left leg pain was admitted to the hospital with intestinal obstruction and a left gluteal mass. Results of needle aspiration suggested the diagnosis, which was confirmed by laparotomy. The sciatic hernia was repaired via a transabdominal approach. RESULTS: The symptoms of sciatic nerve compression and intestinal obstruction resolved fully after surgery. CONCLUSION: The possibility of local pathology causing sciatic nerve compression should be considered when a patient reports sciatic leg pain, particularly if the presentation is atypical. Intestinal obstruction or the presence of a gluteal mass should suggest the possibility of a sciatic hernia.     

Foraminal and extraforaminal lumbar disk herniations

Thirteen patients with foraminal or extraforaminal lumbar disk herniation were treated during a 32-month period. Myelography and magnetic resonance imaging proved to be ineffective in identifying the lesion in most patients. High-resolution computed tomography demonstrated the lesions in all patients, and the findings were subsequently confirmed at surgery. Surgical treatment consisting of disk fragment removal and nerve root decompression was effective in relieving radicular pain.     

Overlooked physical diagnoses in chronic pain patients involved in litigation, Part 2. The addition of MRI, nerve blocks, 3-D CT, and qualitative flow meter

This study followed 120 chronic pain patients referred to a multidisciplinary pain center. The referral diagnosis for many patients, such as "chronic pain," "psychogenic pain," or "lumbar strain," was frequently found to be incomplete or inaccurate (40%) following a multidisciplinary evaluation that used appropriate diagnostic studies, including magnetic resonance imaging, computed tomography, nerve blocks, and qualitative flowmeter. Significant abnormalities were discovered in 76% of the diagnostic tests. An organic origin for pain was found in 98% of these patients. The patients were discharged with objective verification of diagnoses including facet disease, nerve entrapment, temporomandibular joint disease, thoracic outlet syndrome, and herniated discs.     

High- and low-bar squatting techniques during weight-training

STUDY DESIGN: Tissues in the area of herniated lumbar discs were examined for inflammatory cytokines to elucidate the causes of sciatic pain in lumbar disc herniation. OBJECTIVES: To determine the role of inflammatory cytokines in the stimulation of sciatic pain in lumbar disc herniation. SUMMARY OF BACKGROUND DATA: It is postulated that in addition to mechanical compression of lumbar nerve roots and sensory root ganglia by herniated discs, there is a chemical stimulus to the production of sciatic leg pain. The exact mechanisms of chemical stimulation are not clearly defined. METHODS: During surgery, cases of lumbar disc herniation in 77 patients were classified macroscopically into protrusion, extrusion, and sequestration types. Tissues adjacent to nerve roots at the herniation were excised and analyzed biochemically and immunohistochemically for the presence of inflammatory cytokines and for the production of these cytokines and prostaglandin E2 in vitro. RESULTS: The homogenates of samples were analyzed for interleukin-1 alpha, interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha, and granulocyte-macrophage colony stimulating factor, which were detectable. Most of the cytokine-producing cells were histiocytes, fibroblasts, or endothelial cells in extrusion and sequestration types, and chondrocytes in protrusion type. The secretion of these cytokines and prostaglandin E2 was decreased by the addition of betamethasone. The prostaglandin E2 production was dramatically enhanced by additional interleukin-1 alpha, but decreased by the addition of tumor necrosis factor-alpha. CONCLUSION: The results demonstrate that at the site of lumbar disc herniation, inflammatory cytokines such as interleukin-1 alpha are produced, which increases prostaglandin E2 production. Further studies are required to elucidate the role of inflammatory cytokines in causing sciatic pain.     

Pain pattern in pregnancy and "catching" of the leg in pregnant women with posterior pelvic pain

STUDY DESIGN: A cross-sectional study of symptoms and signs in pregnant women. OBJECTIVES: To describe the clinical appearance of back pain in pregnancy and the relation between pain distribution and symptoms in women with posterior pelvic pain, in order to shed light on etiologic factors. SUMMARY OF BACKGROUND DATA: Back pain is common in the general population. During pregnancy, it is even more common, and back pain is experienced by about 50% of pregnant women. In the pregnant woman, differentiation between common low back pain and posterior pelvic pain is believed to be essential because these symptoms should be treated in different ways. METHODS: The women were interviewed with a questionnaire. Those with back symptoms completed a pain drawing and were examined by an orthopedic surgeon. Based on the symptoms and findings, the women were divided into three groups: thoracic pain, lumbar pain, and posterior pelvic pain. RESULTS: Of 335 pregnant women, 51% had back pain at the time of examination. The pain was more widespread compared with common low back pain. Seventy-one percent of the 171 patients examined by the orthopedic surgeon had a positive posterior pelvic pain test. These women more often had pain in the gluteal and posterior thigh regions. A "catching" feeling of the leg was described when walking by 44 of 122 these women, whereas only 1 of 49 women without a posterior pelvic pain test had such symptoms. CONCLUSIONS: The higher prevalence of back pain in pregnancy may be due to several factors. In women with posterior pelvic pain, there is a specific symptom-a catching of the leg when walking. The most probable explanation for the catching is that local nociception disturbs muscular function in women with posterior pelvic pain because changes in the sacroiliac joint range of motion, which is very small, cannot cause this symptom.     

The value of lumbar spine MRI in the assessment of the pars interarticularis

The aim of this study is to assess the ability of conventional lumbar spine magnetic resonance imaging (MRI) to demonstrate the pars interarticularis. The right and left L4 and L5 pars in 50 patients undergoing lumbar spine MRI for low back pain, with or without radiculopathy, were assessed and classified into four types. Based on their appearance, 59 (29.5%) were classified as normal (Type 1), 59 (29.5%) as hypointense (Type 2), 53 (26.5%) could not be demonstrated (Type 3) and 29 (14.5%) were thought to have defects (Type 4). The gold standard was set by the consensus opinion of two consultant musculoskeletal radiologists on the available plain radiographs of the lumbar spine. MRI was found to have a sensitivity of 57% to 86%, specificity of 81% to 82%, positive predictive value of 14% to 18% and negative predictive value of 97% to 99% for the diagnosis of a pars defect.     

Microdecompression and uninstrumented single-level fusion for spinal canal stenosis with degenerative spondylolisthesis

STUDY DESIGN: A retrospective review was completed on 21 patients who had a "least invasive" (one or two level) microdecompression and uninstrumented single-segment lumbar fusion for spinal canal stenosis with degenerative spondylolisthesis. OBJECTIVE: To determine whether a "least invasive" approach to lumbar spinal canal stenosis and degenerative spondylolisthesis would yield acceptable results. SUMMARY OF BACKGROUND DATA: The prevailing surgical technique for symptomatic spinal canal stenosis with degenerative spondylolisthesis is a wide midline decompression and instrumented fusion. METHODS: On an average of 38 months postoperatively, 21 patients were personally assessed on four scores: 1) their overall satisfaction with the outcome of surgery, 2) an analog back and leg pain scale, 3) a functional evaluation scale, and 4) Ferguson (upshot) anterior-posterior lumbosacral and lateral flexion-extension radiographs. RESULTS: The overall satisfactory outcome on all four scales was 16 (76%) of 21. Twenty of twenty-one patients had relief of their claudicant leg pain; the overall fusion rate was 18 (86%) of 21. Two of three patients with a pseudarthrosis had a successful outcome on the patient-oriented outcome (1, 2, and 3) scales (excluding the radiograph scale), and one was a failure. One patient with a solid fusion was a failure because of continuing back pain. One patient with a solid fusion was a failure because of continuing leg pain. The overall satisfactory outcome on the nonradiographic scales was 18 of 21, for an 86% patient satisfaction rate. CONCLUSIONS: In this retrospective study, a "least invasive" surgical approach to lumbar degenerative spondylolisthesis with spinal canal stenosis causing claudicant leg pain produced acceptable results.     

Patterns of ordering diagnostic tests for patients with acute low back pain. The North Carolina Back Pain Project

BACKGROUND: Low back pain is a common reason for visiting a physician. Authors of guidelines and insurance payers are currently scrutinizing use of radiography and computed tomography (CT) or magnetic resonance imaging (MRI). OBJECTIVE: To study the determinants of the use of lumbar spine radiography and either CT or MRI in patients with acute low back pain. DESIGN: Prospective cohort study. SETTING: Community-based practices in North Carolina in six strata: urban primary care physicians, rural primary care physicians, urban chiropractors, rural chiropractors, orthopedic surgeons, and practitioners at a group-model health maintenance organization. PATIENTS: 1580 patients with acute low back pain. MEASUREMENTS: Telephone interviews done after the index office visit and at 2, 4, 8, 12, and 24 weeks or until complete recovery; survey of practitioners; and chart abstraction. RESULTS: During the acute back pain episode, 46% of patients had radiography and 9% had CT or MRI. Patient variables related to use of radiography included pain that began more than 2 weeks before the index visit and no previous episodes of low back pain. Practitioner variables associated with use of radiography were being a chiropractor or orthopedic surgeon and having a solo practice. Use of CT or MRI was associated with white race, neurologic deficit at baseline, sciatica, poor functional status at baseline, and small group-practice size. Practitioners' responses to clinical vignettes were associated with aggregate practitioner behavior: In the vignettes and in real life, practitioners were more likely to order CT for patients with sciatica. However, a practitioner's response to a vignette did not predict that practitioner's use of CT or MRI for similar patients in his or her own practice. CONCLUSION: Radiography is commonly used as a diagnostic test for patients with acute back pain. Clinical factors and provider specialty are major correlates of the use of imaging studies.