Pulsed electromagnetic field stimulation may improve fusion rates in cervical arthrodesis in high-risk populations.

OBJECTIVES: Pulsed electromagnetic field (PEMF) stimulation was evaluated after anterior cervical discectomy and fusion (ACDF) procedures in a randomized, controlled clinical study performed for United States Food and Drug Administration (FDA) approval. PEMF significantly increased fusion rates at six months, but 12-month fusion outcomes for subjects at elevated risk for pseudoarthrosis were not thoroughly reported. The objective of the current study was to evaluate the effect of PEMF treatment on subjects at increased risk for pseudoarthrosis after ACDF procedures. METHODS: Two evaluations were performed that compared fusion rates between PEMF stimulation and a historical control (160 subjects) from the FDA investigational device exemption (IDE) study: a post hoc (PH) analysis of high-risk subjects from the FDA study (PH PEMF); and a multicentre, open-label (OL) study consisting of 274 subjects treated with PEMF (OL PEMF). Fisher's exact test and multivariate logistic regression was used to compare fusion rates between PEMF-treated subjects and historical controls. RESULTS: In separate comparisons of PH PEMF and OL PEMF groups to the historical control group, PEMF treatment significantly (p < 0.05, Fisher's exact test) increased the fusion rate at six and 12 months for certain high-risk subjects who had at least one clinical risk factor of being elderly, a nicotine user, osteoporotic, or diabetic; and for those with at least one clinical risk factor and who received at least a two- or three-level arthrodesis. CONCLUSION: Adjunctive PEMF treatment can be recommended for patients who are at high risk for pseudoarthrosis.Cite this article: D. Coric, D. E. Bullard, V. V. Patel, J. T. Ryaby, B. L. Atkinson, D. He, R. D. Guyer. Pulsed electromagnetic field stimulation may improve fusion rates in cervical arthrodesis in high-risk populations. Bone Joint Res 2018;7:124-130. DOI: 10.1302/2046-3758.72.BJR-2017-0221.R1.

The relation between cervical discographic pain responses and radiographic images.

OBJECTIVE: The purpose of this study was to investigate the relation between cervical discographic pain responses and radiographic images. DESIGN: Records were reviewed for a series of patients who had undergone cervical discography. SETTING: All patients were being treated at a spine specialty clinic. PATIENTS: A total of 269 discs were studied in 161 discographic procedures in patients with neck, shoulder, or arm pain. All patients underwent other diagnostic procedures before discography, including magnetic resonance imaging, computed tomography (CT), and CT/myelography. INTERVENTIONS: During the injection of contrast in each disc evaluated, the patient was asked if any pain was felt, and if so, was it similar or dissimilar to the pain typically experienced. OUTCOME MEASURES: Results were determined by analyzing the pain responses during disc injection with respect to imaged pathology seen on the axial CT discographic image of the disc. Results were further analyzed based on patient age. RESULTS: There was a significant relation between the radiographic image of the disc and the results of clinical pain provocation (p < 0.01; chi2). Among the 35 discs appearing as normal, clinical pain was provoked in only 14.3%. Among the 234 discs appearing as abnormal, clinical pain was provoked in 77.8%. The mean age of the patients with painless radiographically abnormal discs was significantly greater than that of the patients in the other subgroups of the study population. CONCLUSIONS: There was good agreement between the radiographic appearance of the disc and the pain provocation results. Discs that were painless but disrupted were found among older patients. Among such patients, discography may be particularly helpful in differentiating clinically significant abnormalities from those associated with aging.

The detection and prevention of pulmonary embolism in total hip replacement. A study comparing aspirin and low-dose warfarin.

Because of the controversy surrounding prophylaxis for thromboembolism after total hip surgery, we undertook a prospective study comparing the results of the administration of aspirin with that of low doses of warfarin in 194 patients (200 hips) undergoing total hip replacement. The incidences of both clinically apparent and silent (asymptomatic) pulmonary emboli were determined using the objective criteria of preoperative and postoperative levels of arterial blood gases, chest roentgenograms, electrocardiograms, and perfusion lung scans. With this surveillance plan, the accuracy of diagnosis of clinically symptomatic pulmonary emboli was improved and the detection of otherwise silent pulmonary emboli became possible. The group of patients who received low doses of warfarin showed a 6 per cent total incidence of pulmonary emboli compared with a 19 per cent incidence in the group receiving aspirin (p less than 0.05). There was, however, no significant difference when the incidences of only the clinically suspected emboli were compared, the rates for the two groups being 5 and 8 per cent, respectively (p greater than 0.05). There was also no significant difference between men and women with regard to the prophylactic efficacy of aspirin in preventing pulmonary embolism.

Lumbar discography. Position statement from the North American Spine Society Diagnostic and Therapeutic Committee.

STUDY DESIGN: A comprehensive review of the literature dealing with lumbar discography was conducted. OBJECTIVE: The purpose of the review was to generate a position statement addressing criticisms of lumbar discography, identify indications for its use, and describe a technique for its performance. SUMMARY OF BACKGROUND DATA: Lumbar discography remains a controversial diagnostic procedure. There are concerns about its safety and clinical value, although others support its use in specific applications. METHODS: Articles dealing with lumbar discography were reviewed and summarized in this report. RESULTS: Most of the recent literature supports the use of discography in select patients. Although not to be taken lightly, many of the serious and high complication rates were reported before 1970 and have decreased since because of improvement in injection technique, imaging, and contrast materials. CONCLUSIONS: Most of the current literature supports the use of discography in select situations. Particular applications include patients with persistent pain in whom disc abnormality is suspect, but noninvasive tests have not provided sufficient diagnostic information or the images need to be correlated with clinical symptoms. Another application is assessment of discs in patients in whom fusion is being considered. Discography's role in such cases is to determine if discs within the proposed fusion segment are symptomatic and if the adjacent discs are normal. Discography appears to be helpful in patients who have previously undergone surgery but continue to experience significant pain. In such cases, it can be used to differentiate between postoperative scar and recurrent disc herniation and to investigate the condition of a disc within, or adjacent to, a fused spinal segment to better delineate the source of symptoms. When minimally invasive discectomy is being considered, discography can be used to confirm a contained disc herniation, which is generally an indication for such surgical procedures. Lumbar discography should be performed by those well experienced with the procedure and in sterile conditions with a double needle technique and fluoroscopic imaging for proper needle placement. Information assessed and recorded should include the volume of contrast injected, pain response with particular emphasis on its location and similarity to clinical symptoms, and the pattern of dye distribution. Frequently, discography is followed by axial computed tomography scanning to obtain more information about the condition of the disc.

The association between pain drawings and computed tomographic/discographic pain responses.

STUDY DESIGN: Pain drawings were scored and their relationship to discographic pain responses was investigated. OBJECTIVES: The purpose of this study was to determine if there was a relationship between patients indicating pain in nonanatomic patterns on pain drawings (possibly suggestive of a tendency to overreport pain) and discographic pain responses, and in particular, if patients with abnormal drawings were more likely to provide false-positive discographic pain reports. SUMMARY OF BACKGROUND DATA: Patients with abnormal pain drawings have been found to have elevated scores on the hysteria and hypochondriasis scales of the Minnesota Multiphasic Personality Inventory. Elevations on these same two scales have been related to discordant discographic pain reports. METHODS: Pain drawings were completed by 170 patients the day of, but before computed tomography/discography. The drawings were scored as described by Ransford et al and classified as normal or abnormal. The number of levels at which a patient reported pain and the incidence of false-positive computed tomographic/discographic pain reports were compared for the two pain drawing groups. RESULTS: Patients with abnormal drawings reported pain at more levels than patients with normal ones. When dealing specifically with false-positive pain reports (pain reproduction on the injection of a nondisrupted disc), among the 105 patients in the normal group, only 13 (12.3%) reported false-positive pain. This was significantly less than the 50.0% (18 of 36) reporting false-positive pain in the abnormal group. The overall accuracy of pain drawings in differentiating patients with false-positive pain reports was 78.0% (110 of 141). CONCLUSIONS: There is a relationship between pain drawings and discographic pain responses. Pain drawings can help identify patients who may be likely to report pain on injection of a nondisrupted disc. While it was not totally sensitive to this occurrence, it can help identify at least some of the patients in whom pain responses should be interpreted cautiously.

Discographic pain report. Influence of psychological factors.

STUDY DESIGN: The possibility of a relationship between discographic pain responses and Minnesota Multiphasic Personality inventory scores was investigated. OBJECTIVES: To determine if patients with elevated Minnesota Multiphasic Personality Inventory scale scores were more likely to report pain on the injection of a nondisrupted disc than were patients without such high scores. SUMMARY OF BACKGROUND DATA: In general, injection into disrupted discs provokes pain, whereas injection into nondisrupted discs does not. However, discordant results are sometimes obtained and create a more difficult diagnostic challenge. METHODS: The primary study group was composed of 72 patients who underwent computed tomography/discography at the three lowest lumbar levels for diagnostic purposes and completed the Minnesota Multiphasic Personality Inventory. RESULTS: The mean scores on the Minnesota Multiphasic Personality Inventory hypochondriasis and hysteria scales were significantly greater for patients reporting reproduction of clinical pain than for patients not reporting pain on injection of a nondisrupted disc (hypochondriasis: 77.2 vs. 68.6, P < 0.01; hysteria: 74.5 vs. 68.3, P < 0.05). The scores on the depression scale followed a similar trend (68.6 vs. 63.6, P < 0.15). Multivariate analysis, adjusting the means for possible confounding effects of age, symptom duration, and sex, did not alter the results. CONCLUSIONS: Discographic pain reports are not only related to anatomic abnormalities, but are influenced by personality as assessed by the Minnesota Multiphasic Personality Inventory. Patients with elevated scores on the hypochondriasis, hysteria, and depression scales may tend to overreport pain during discographic injection. Among such patients, even those with a concordant computed tomography/discographic image, selection of therapeutic modalities should be made with caution.

Radiographic assessment for patients with low back pain.

Guidelines for radiographs of the lumbar spine are established. In general, radiographs are not believed to be necessary for a first episode of low back pain present for less than 7 weeks. Exceptions to this include various medical or physical findings, which are listed. In general, anteroposterior and lateral views only should be done initially. Indications for other views are discussed.

Early changes in bone mineral density above a combined anteroposterior L4-S1 lumbar spinal fusion. A clinical investigation.

STUDY DESIGN: Fifteen patients meeting rigid study entrance criteria for undergoing a combined anteroposterior L4-S1 spinal fusion as a first time operation were included in the study. Bone mineral density changes at adjacent segments (L3 and L2) were assessed by scanning patients in the anteroposterior and lateral projections before surgery and 3 and 6 months after surgery. OBJECTIVES: To prospectively evaluate changes in bone mineral density at adjacent segments after lumbar spinal fusion and postoperative bracing. SUMMARY OF BACKGROUND DATA: The majority of studies investigating changes in bone mineral density after spinal fusion have been performed in canines. Although such work has provided valuable insight, its application to humans is questionable because the loading mechanics are so different. METHODS: Bone mineral density was assessed noninvasively by dual energy x-ray absorptiometry in the lateral and anteroposterior projections. Data were analyzed with special edge detection software. RESULTS: In the lateral projection at L3, one level above the fusion, the preoperative bone mineral density was 0.91 +/- 0.24 (mean +/- standard deviation in g/cm2). This decreased significantly at 3 months to 0.82 +/- 0.24 and remained reduced at 6 months (0.80 +/- 0.21). This reflected a loss of primarily trabecular bone. In the anteroposterior projection at L2, there was a significant loss at 3- and 6-month follow-up (1.24 +/- 0.15 to 1.19 +/- 0.15 and 1.19 +/- 0.14). This may reflect changes at either or both of the anterior and posterior columns. CONCLUSION: Significant decreases in bone mineral density were noted above fused lumbar segments. This may have been related to immobilization or altered mechanics associated with arthrodesis. Trabecular bone of the axial skeleton is most responsive to change, compared with cortical bone, because of the higher metabolic activity. This may explain the reduction of bone mineral density at L3. Changes at L2 may have been related to altered loads at the anterior or posterior columns and should be further investigated.

Laser disc decompression. The importance of proper patient selection.

STUDY DESIGN: The value of adherence to selection criteria for laser disc decompression (LDD) was evaluated. A total of 204 patients who underwent LDDs were identified. Follow-up information could be obtained for 164 (80.8%) patients. Results were compared based on the selection criteria. SUMMARY OF BACKGROUND DATA: Laser disc decompression is a relatively new procedure. Few reports concerning outcome of LDD exist; and none deal specifically with patient selection. OBJECTIVE: This study compared the results of LDD performed among patients who met appropriate selection criteria with those who did not. Also, the value of discography in patient selection for LDD was investigated. METHODS: Two independent reviewers extracted data from patient charts. From this information, each patient was assigned to one of three groups: 1) those who met all selection criteria for LDD (leg pain, positive physical examination finding such motor, sensory, or reflex deficits, and/or straight leg raise, contained disc herniation confirmed by discography); 2) those who did not meet the selection criteria (had a normal physical examination, the presence of stenosis, spondylolisthesis, extruded disc fragment, leakage of discographic dye from the outer annulus, multiple prior lumbar surgeries); or 3) those who could not be assigned to either of the first two groups for reasons such as discography not being performed or inadequate physical examination data recorded in the chart. At 1 year follow-up, each patient was sent a questionnaire assessing outcome. Successful outcome was defined to be no subsequent lumbar surgery, the patient felt that LDD had helped, and if the patient was working before symptom onset, he was able to work at the time of follow-up. RESULTS: Among the 41 patients who met all selection criteria, the success rate was 70.7% (29/41); among patients who did not meet all the criteria, the success rate was only 28.6% (12/42); significantly less than in the first group (P < 0.005). Among patients who could not be assigned definitively to either of the first two groups, the success rate was 55.6% (45/81). Also, the success rate among patients with discographic confirmation of a contained disc herniation was significantly greater than among those who either did not have discography performed or extravasation of contrast was noted (70.7% vs. 44.4%, P < 0.035). CONCLUSIONS: These results emphasize the importance of strict adherence to appropriate selection criteria to obtain satisfactory results from LDD.

Intradiscal pressure measurements above an instrumented fusion. A cadaveric study.

STUDY DESIGN: An in vitro study to determine the intradiscal pressure changes during flexion in levels above a simulated fusion was performed. OBJECTIVES: To determine if intradiscal pressure increases more during flexion in discs above an instrumented spinal segment compared to an uninstrumented segment. SUMMARY OF BACKGROUND DATA: The progressive degeneration of intervertebral discs adjacent to a fused or fixed segment is a phenomenon that is noted but poorly understood. Intuitively, the degeneration appears to be a function of altered biomechanics of the motion segments in the spine. METHODS: Two intervertebral disc levels were evaluated, L3-L4 and L4-L5 from each of six fresh frozen cadaver spines. Pressure measurements were taken with the spine uninstrumented, with bilateral pedicle screw-rod instrumentation from L5 to S1, and with bilateral pedicle screw-rod instrumentation from L4 to S1. Pressure measurements were accomplished with Millar Mikro-Tip pressure transducers. The transducers were placed within the nucleus pulposus of L3-L4 and L4-L5 intervertebral discs. Pressure data were recorded by computer data acquisition. The pressure data were compared by intervertebral level and by the effects of added instrumentation. RESULTS: In general, the addition of instrumentation significantly affected the intradiscal pressure in the levels above a simulated fusion. The intradiscal pressure increased as the amount of levels involved in the simulated fusion increased. The intradiscal pressure increased as flexion motion increased. A greater increase was seen at the L4-L5 level than the L3-L4 level. When L5-S1 fixation was added, the intradiscal pressure increased. When L4-S1 fixation was added, the intradiscal pressure further increased. CONCLUSION: This study demonstrated increasing intradiscal pressures during flexion.

Alar transverse process impingement of the L5 spinal nerve: the far-out syndrome.

This syndrome occurs in two types of patients: (1) the elderly person with degenerative scoliosis and (2) a somewhat younger adult population with isthmic spondylolisthesis and at least 20% slip. On plain radiograph, the Ferguson view (25 degrees caudocephalic) is best for visualizing the condition, however, CT is by far the best diagnostic tool. To show this far laterally, the "window" on the CT scanner must be opened wider than usual. Both coronal and parasagittal views will demonstrate the condition, but the coronal is the most valuable. Symptoms are classical spinal nerve compression. Usually it is the L5/S1 level that is involved, but other levels can be. At surgery, it is most important that nerve decompression be carried far enough laterally. This can mean sacrificing the lower half of the pedicle and the entire transverse process. Part of the body of S1 and of the sacral ala can be removed if the surgeon prefers. Because so much bone is removed, instability is a factor to be seriously considered. How to decompress adequately and still maintain stability often poses a most difficult problem.

Magnetic resonance imaging. Use in patients with low back or radicular pain.

With the current emphasis on cost containment, it is important to order the single best diagnostic test when clinical uncertainties must be resolved. Magnetic resonance imaging is currently the optimal imaging modality to provide the maximum amount of information when evaluating patients with suspected spinal disorders. A comprehensive magnetic resonance imaging study is needed along with a subspecialty interpretation to provide the greatest amount of useful clinical information.

The relationship of facet tropism to degenerative disc disease.

The role of facet tropism (asymmetry) in the pathogenesis of degenerative disc disease is unknown, and several conflicting reports have been published. We studied this association using CT/discography performed at 324 lumbar levels (108 patients). The stage of disc degeneration as well as the patient's pain response upon discographic injection were scored using a standardized protocol. The facet angles were measured directly from the axial CT/discographic images and defined, in each case, as the angle formed by the facet orientation with respect to the midsagittal plane. The facet tropism angle was defined as the difference between the left and right facet angles at each disc level. The mean and standard deviation (SD) of the tropism angles were calculated. From this calculation, each pair of facet joints was classified as symmetric (within 1 SD of the mean), moderately asymmetric (between 1 and 2 SD), or severely asymmetric (beyond 2 SD of the mean). There were no differences in degree of disc degeneration or pain response with respect to the facet tropism. The total facet angle was also studied. The total facet angle was greater at the more caudal levels. The total angle size was not associated, however, with disc degeneration or pain provocation. These findings do not support the hypothesis that there is an association between facet tropism and degenerative lumbar disc disease.

A comparison of CT/discography, pain response and radiographic disc height.

CT/discograms of 107 low-back patients were classified by annular degeneration, annular disruption, and pain response. These parameters were compared with the heights of the corresponding discs. Disc height correlated significantly with degenerative annular changes. Comparison of the painless and exact reproduction groups at the L5-S1 level showed a significant increase in exact pain reproduction in narrow discs compared with normal discs. Discs demonstrating slight degenerative changes were often painful but narrowing was detected only when degeneration increased to moderate or severe levels. Some severely degenerated discs were painless and only part of the severe group was narrow. Measuring disc height is a poor method for detecting early, painful degeneration changes.

Discitis after discography.

A series of nine patients with post-discography discitis were evaluated to help delineate the clinical course. The most consistent sign was the marked exacerbation of neck or back pain. This then was followed by an elevated sedimentation rate at an average of 20 days, followed by a positive bone scan at an average of 33 days. Of note is that seven patients initially had negative bone scans at an average of 18 days. Five out of nine patients had changes on plain roentgenograms between 14 and 51 days after discography. Magnetic resonance imaging was performed in six patients; two of these patients were scanned twice. Three scans were negative and five were positive (2 patients initially had negative scans that later became positive). The course of lumbar discitis ranged from 8 to 11 weeks, and cervical discitis from 6 to 7 weeks, with the latter usually resulting in spontaneous fusion.

The relationship of pain provocation to lumbar disc deterioration as seen by CT/discography.

The CT/discographic findings from 225 discs in 91 low-back pain patients were compared to the pain provocation during the injection of contrast into the disc. The radiographic appearance of disc deterioration demonstrating disc degeneration and annular disruption of each disc was classified separately using a fourpoint scale: normal, slight, moderate, or severe. Pain reaction to the discogram at each level was recorded as follows: no pain, dissimilar pain, similar pain, or exact reproduction of the patient's clinical pain. This more precise analysis demonstrated a significant relationship between pain and deterioration of discs. The CT/discogram presents an axial view of the disc that allows a subgrouping of disc deterioration that can discriminate between peripheral deterioration (degeneration) and internal deterioration (disruption). The disruption supposedly occurs earlier and is more likely to be the source of exact pain reproduction.

Pain provocation and disc deterioration by age. A CT/discography study in a low-back pain population.

The computed tomography (CT)/discograms and discographic pain provocation reports of 291 clinical patients, 790 discs (mean age, 38; range, 17-79) were collected. The CT/discograms were classified separating anular disruption and degeneration and recording the pain provoked during discography as no pain, dissimilar, similar, or exact reproduction of the patient's clinical pain. Nondegenerated discs usually were found to be painless, and deteriorated discs painful. The proportion of severely degenerated but painless discs increased with age, as did the discs producing dissimilar pain. This may help explain the poor correlation of low-back pain with radiographic degenerative changes reported in previous epidemiologic studies.

Extraosseous spinal lesions mimicking disc disease.

To identify characteristics of patient presentation that would help distinguish extraosseous spinal tumors from the more common herniated disc, nine cases of intraspinal tumors were reviewed. These nine patients were identified in a group of 744 patients who presented with symptoms similar to disc herniation but failed to respond to conservative care and underwent spinal surgery. This study indicates that intraspinal tumor should be suspected in patients with the following characteristics: 1) painless neurological deficit; 2) night pain or pain which increases in the supine position; 3) pain disproportionate to that normally expected with lumbar disc disease; 4) no change in symptoms after successful surgery for herniated disc; 5) elevated spinal fluid protein; or 6) a teenager with symptoms of disc herniation. Myelography is an effective radiologic procedure for the diagnosis of spinal tumor but MRI should be equally effective if the procedure includes a scan of the conus as well as cauda equina.

Proplast reconstruction of iliac crest defects.

Proplast reconstruction of iliac crest defects resulting from bone grafts taken for anterior lumbar and cervical fusions is described. The procedure improves the cosmetic result, prevents postoperative muscle herniation and may decrease postoperative donor site pain. It is a simple procedure with low complication rate when performed in the manner described.

Anterior lumbar interbody fusion.

This is a report of 85 patients who underwent anterior lumbar interbody fusion (ALIF) for treatment of painful disc disruption (PDD) or symptomatic pseudarthrosis. The fusion rate was 80% by disc. The pseudarthrosis rate increased from 16% at L5-S1 to 21% and 31% at L4-5 and L3-4, respectively. There was a significant increase in pseudarthrosis rate in patients who smoked more than one pack per day. There was no difference in the fusion rate whether autogenous or cadaveric iliac crest graft or dowel versus tricortical block graft was used. Sixty-eight percent of patients were "able to work" after ALIF. The complication rate was low and retrograde ejaculation occurred in only one patient.