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Biomedical subjects

B Strömqvist

Publications and source records attributed to B Strömqvist.

At least 19 recordsLinked to original sources
PubMed2001

Visual analog scales for interpretation of back and leg pain intensity in patients operated for degenerative lumbar spine disorders.

STUDY DESIGN: A prospective observational study of visual analog scale (VAS) scores for pain in patients operated at one institution within the framework of a national registry. OBJECTIVE: To describe the use of recording VAS for pain intensity in patients operated on for lumbar spine problems. SUMMARY OF BACKGROUND DATA: There is no consensus regarding pain outcomes assessment in spine patients. Pain intensity, recorded on a VAS, is one of the most used measures. Still, many aspects of its interpretation are still debated or unclear. METHODS: A total of 755 consecutive patients, mean age 50 years (range, 15-86 years), operated from 1993 to 1998 were included in the study; there were 420 males and 335 females. Diagnoses included herniated nucleus pulposus (45%), central stenosis (19%), lateral stenosis (14%), isthmic spondylolisthesis (9%), and degenerative disc disease (9%). Local pain, radiating pain, analgesic intake, and walking ability were recorded before surgery and at 4 and 12 months after surgery. The patients' opinions regarding the change in pain and satisfaction with the result were assessed separately. Correlation among variables reflecting perceived pain was sought. RESULTS: Preoperative VAS mean values for local and radiating pain were significantly different in the five diagnostic groups. Significant but moderate correlation between different types of pain outcomes and with patient satisfaction was present in all cases. CONCLUSIONS: Measuring pain intensity with VAS is a useful tool in describing spine patients. In the search for a standard in the evaluation of pain as an outcome, the differences between the various methods should be taken into account.

Adolescent↗
PubMed2000

Is there increased intervertebral mobility in isthmic adult spondylolisthesis? A matched comparative study using roentgen stereophotogrammetry.

STUDY DESIGN: By roentgen stereophotogrammetric technique, the intervertebral mobility of the spondylolytic segment in eight patients was measured and compared with the mobility of eight nonspondylolytic patients matched according to sex, afflicted segment, and grade of disc degeneration. OBJECTIVES: To compare the intervertebral mobility of a spondylolytic segment with the mobility of a segment without spondylolysis in adult patients with back pain. SUMMARY OF BACKGROUND DATA: Evidenced by the resulting olisthetic deformity and supported by the outcome from prior investigations, spondylolysis is assumed to induce spinal segmental instability/hypermobility. METHODS: After percutaneous application of tantalum indicators for roentgen stereophotogrammetric technique, the intervertebral translations of the spondylolytic fifth lumbar vertebra were measured in eight adult patients with low back pain and low-grade olisthesis. Eight other patients without spondylolysis but with low back pain presumably on degenerative basis were chosen for comparison and had an identical measuring procedure using roentgen stereophotogrammetric technique. The two groups were matched in pairs according to sex, afflicted segment, and grade of disc degeneration. RESULTS: No significant difference was registered considering the intervertebral mobility for matched pairs in the two groups neither along the sagittal nor the vertical axis. The transverse translations were mostly negligible in both groups. CONCLUSION: The spondylolytic defect in pars interarticularis does not cause permanent instability/hypermobility detectable in the adult patient with low back pain and low-grade olisthesis.

Adult↗
PubMed2000

A method to evaluate the in vivo behaviour of lumbar spine implants.

The aim of the study was to design a method for evaluating the stabilizing effect of different lumbar spine implants in vivo, and to apply this method to a comparison of plates versus rods in lumbar spine posterolateral fusion using transpedicular screw fixation. Fourteen patients, seven operated on with transpedicular plates and screws (VSP), and seven operated on with rods and screws (Diapason), matched according to number of levels fused, had tantalum markers inserted in the vertebrae at surgery, enabling roentgen stereophotogrammetric analysis (RSA). Mean patient age was 45 (range 33-56) years. In each group, two patients underwent fusion between L4 and L5, three between L5 and S1, and two from L4 to S1. In three patients, concomitant nerve root decompression was performed using a facet joint preserving technique. RSA was performed 4 weeks after surgery. This interval was chosen to allow enough time for soft tissue healing, but not fusion healing, to occur. RSA was performed in supine and standing position without any mobility provocation, in line with the postoperative regimen given. Movements between the outermost vertebrae of the fusion were calculated along the transverse, vertical and sagittal axes. The method of measurement along these three axes has previously been determined to be accurate to 0.3, 0.6 and 0.7 mm, respectively. One patient stabilized with rods and screws between L5 and S1 displayed a sagittal translation of 1.01 mm but no mobility along the transverse or vertical axes. In the remaining 13 patients, positional change from supine to standing did not provoke any intervertebral mobility above the RSA accuracy along any of the axes. With the limited provocation described, in line with the postoperative regimen for lumbar fusion patients, plates with transpedicular screws and rods with transpedicular screws both seem to give adequate intervertebral stability in posterolateral lumbar fusions.

Adult↗
PubMed1999

Stability of lumbar fusion with transpedicular fixation determined by roentgen stereophotogrammetric analysis.

STUDY DESIGN: An evaluation of the intervertebral stability of transpedicular instrumentation in posterolateral lumbar fusions by roentgen stereophotogrammetric analysis. OBJECTIVES: To determine the in vivo intervertebral stability of posterolateral lumbar fusions augmented with transpedicular screws and plates. SUMMARY OF BACKGROUND DATA: Transpedicular bone screw systems have been found to be as safe and clinically effective as other types of devices in stabilizing surgery of the spine. Many experimental studies have yielded basic data on the stabilizing implant effect in vitro, but the exact in vivo stabilizing effect on human lumbar vertebrae has not been presented previously. METHODS: In 12 patients, the intervertebral stability of posterolateral fusion in the lower lumbar spine augmented with transpedicular screws and plates was evaluated by serial roentgen stereophotogrammetric analysis with the patients in supine and erect positions 1 year after surgery. RESULTS: Screws in each fused vertebra yielded stable fixation or permitted sagittal intervertebral translations smaller than 1 mm induced by the positional change. A widely decompressed and destabilized vertebra without screw fixation yielded persisting intervertebral translations. CONCLUSIONS: The current study demonstrated the adequacy of in vivo stability of lumbar fusions augmented with transpedicular screws and plates. Sagittal translation seems easier to elicit than movements along the other three-dimensional axes. A widely decompressed and destabilized vertebra without screw fixation increases the risk for persisting intervertebral translations. The roentgen stereophotogrammetric analysis technique described seems to be a good way of comparing the in vivo behavior of different implant systems.

Adult↗
PubMed1999

Incomplete incorporation of morselized and impacted autologous bone graft: a histological study in 4 intracorporally grafted lumbar fractures.

Morselized and impacted bone allografts are used successfully in hip and knee revisions, but experiments using bone chambers indicate that impaction actually can delay ingrowth of new bone into a graft. To understand the remodeling and incorporation process of morselized and impacted grafts, we studied the incorporation of morselized impacted autografts in lumbar fractures histologically. 4 patients were operated on for Th XII-LI fractures. The fractures were stabilized by VSP plates and transpedicular screws in the vertebrae above and below the fractured one. Autologous bone graft was packed into the fractured vertebral body through one of the pedicles. After 18-20 months, the plates were removed and biopsies were obtained from various locations in the fractured vertebra. All fractures were at this time clinically and radiographically healed. Histologically, in all cases, large areas of the autograft in the vertebral body were unvascularized and partially or entirely necrotic. As with morselized bone in hip revisions, evaluation of graft incorporation requires histological examination. Full osseous incorporation of a graft is not always necessary for a good clinical result.

Bone Marrow↗
PubMed1999

Lumbar nerve root compression by intraspinal synovial cysts. Report of 8 cases.

We evaluated the clinical appearance and results of surgical treatment in 8 patients with leg symptoms due to a lumbar intraspinal synovial cyst. The most frequent symptom was radicular leg pain due to unilateral single-root compression affecting the L5 or S1 nerve root. There were 2 cases with large cysts causing compression of the cauda equina, with spinal claudication as the main symptom. All cysts arose from arthrotic facet joints. Surgical excision gave good results and no recurrences have been noted 0.5-2 years postoperatively.

Aged↗
PubMed1999

Significance of a persistent positive straight leg raising test after lumbar disc surgery.

OBJECT: Results of the straight leg raising (SLR) test provide the clinician with valuable information regarding possible causes of a patient's pain. In a previous study the results have also demonstrated a correlation between the outcome of the test and the severity of pain, as well as the prognostic value of the test; patients for whom the SLR test is persistently positive postoperatively appear to have a poorer short-term outcome. In a prospective study of 200 consecutive patients who underwent surgery for disc herniation, the authors evaluated the frequency of repeated surgery and outcome of surgery in patients with a persistent postoperative positive SLR test. METHODS: The preoperative radiological evaluation included myelography, computerized tomography scanning, and/or magnetic resonance imaging. Preoperatively as well as 4, 12, and 24 months postoperatively, each patient was interviewed and examined using a standard protocol in which common symptoms and signs were described. The result of the SLR test was also classified into one of four categories: positive 0 to 30 degrees ; positive 30 to 60 degrees, positive greater than 60 degrees, or negative, and the surgical results were evaluated using a four-grade scale. Preoperatively, the SLR test was positive in 86% of patients. At 4 months postoperatively, 22% still had a positive SLR test. For the patients whose SLR test was positive 4 months postoperatively, the long-term outcome at all three follow-up examinations was inferior; this difference was statistically significant. CONCLUSIONS: During the 2-year period, the reoperation rate was 18% (eight of 44) in patients with a positive postoperative SLR test compared with 4.5% (seven of 156) in patients whose postoperative SLR test was negative. A postoperative positive SLR test thus correlates to an unfavorable surgical outcome.

Adult↗
PubMed1999

External pedicular fixation of the lumbar spine: outcome evaluation by functional tests.

We analyzed the pain-relieving effect and the functional outcome during external pedicular fixation of the lumbar spine. Twenty patients were included, and the diagnoses were disc degeneration with or without facet joint arthrosis in eight patients, pain after decompression in six patients, spondylolysis/olisthesis in two patients, other types of lumbar anomalies in three patients, and pseudarthrosis after prior uninstrumented fusion in one patient. Before application of the external frame, the pain level on the Visual Analogue Scale was registered at rest, as a mean level for the preceding week, and at seven different functional tests. Maximum walking capacity and walking time needed for a standardized distance were also measured. The same test procedure was repeated 1 week postoperatively with the external frame applied in locked position. With stabilization, 11 patients reported pain relief at rest and 14 when approximating the mean pain level for the week. Both these measured levels correlated to the pain level at all of the seven functional tests. Thus, the patients selected for a subsequent fusion based on pain relief during extended functional provocation would not differ from the patients selected by using only the pain-relieving effect at rest. The patients reporting pain relief tended to increase their walking distance (p = 0.06, t test) but not the speed of walking.

Adult↗
PubMed1998

Assessment of sagittal plane segmental motion in the lumbar spine. A comparison between distortion-compensated and stereophotogrammetric roentgen analysis.

STUDY DESIGN: Sagittal plane translatory and rotatory motion was measured in 15 lumbar motion segments of 8 patients by distortion-compensated and stereophotogrammetric Roentgen analysis. OBJECTIVE: To compare measurement precision of the new distortion-compensated Roentgen analysis protocol with that of the established Roentgen stereophotogrammetric technique under realistic clinical conditions. SUMMARY OF BACKGROUND DATA: Roentgen stereophotogrammetric analysis constitutes the most precise method available to assess segmental motion. Because of the invasive nature of the procedure, however, there is interest in alternative, noninvasive protocols suitable for studying larger patient cohorts. METHODS: In 8 patients, segmental motion of 15 lumbar segments that had undergone previous spinal surgery was assessed from stereo views by using Roentgen stereophotogrammetric analysis. Sagittal plane segmental motion was assessed by distortion-compensated Roentgen analysis. Sagittal plane translatory and rotatory motion data obtained by both methods were compared. RESULTS: With respect to Roentgen stereophotogrammetric analysis, sagittal plane rotation was determined by distortion-compensated Roentgen analysis with an error (standard deviation) of 1.4 degrees and a mean difference of less than 0.05 degree. Sagittal plane translation was determined by distortion-compensated Roentgen analysis, with an error of 1.25 mm and a mean difference 0.5 mm. CONCLUSION: Measurement precision of distortion-compensated Roentgen analysis is slightly inferior to that of Roentgen stereophotogrammetric analysis but substantially higher than that of conventional protocols assessing lumbar segmental motion. If measurement precision is considered adequate and if a noninvasive technique is indicated, distortion-compensated Roentgen analysis can be used to provide reliable motion data required for epidemiologic and clinical studies.

Adult↗
PubMed1998

Contained and noncontained lumbar disc herniation in the same patient. Two case reports.

STUDY DESIGN: A case report containing description of symptoms, signs, and selected treatment in two patients with lumbar disc herniation where the type of herniation changed from contained to noncontained in less than 1 year. OBJECTIVES: To demonstrate the difference in clinical appearance related to the type of herniation. SUMMARY OF BACKGROUND DATA: The clinical appearance of lumbar disc herniation regarding onsets of symptoms, severity of pain, and clinical findings are related to the type of herniation, as is the treatment. METHODS: Two cases reports are presented with description of anamneses, clinical findings, neuroradiographic findings, and treatment. RESULTS: Both patients suffered from a transient left-side sciatica due to a contained lumbar disc herniation, improved by physiotherapy. After several months, both patients had an instantaneous increase in contralateral leg pain, and the recurrent, intense pain was caused by a sequestration of the previous contained herniation. The neurologic findings were more severe, and the patients were operated on, with subsequent improvement. CONCLUSIONS: The case reports illustrate the difference in clinical appearance of disc herniation related to the type of herniation, with a more aggressive clinical appearance in conjunction with perforation of the posterior longitudinal ligament with extrusion of disc material.

Adult↗
PubMed1997

A prospective and consecutive study of surgically treated lumbar spinal stenosis. Part I: Clinical features related to radiographic findings.

STUDY DESIGN: A prospective study of consecutive patients undergoing surgery for central lumbar spinal stenosis. OBJECTIVES: To evaluate symptoms and signs in patients undergoing surgery for central spinal stenosis and to correlate the findings to age, preoperative duration of symptoms, and radiographically detected constriction. SUMMARY OF BACKGROUND DATA: The degree of constriction of the spinal canal considered to be symptomatic of lumbar canal stenosis is not clear, nor is the relation between the clinical appearance of the disease and the degree of radiographically verified constriction. MATERIAL AND METHODS: One hundred five consecutive patients scheduled for decompression surgery were included in a prospective study. The day before surgery, all patients were interviewed and examined, using a defined protocol that included data on age, gender, preoperative duration of symptoms, walking ability, and occurrence of pain at rest and at night. Included were data recording straight leg raising test results, reflex disturbance, and extensor hallucis longus muscle weakness. All radiographs were examined by a neuroradiologist. The anteroposterior diameters at each site from L1-L2 to L5-S1 were recorded. For the computer analysis, the site of and width at the narrowest site was registered, as well as the number of sites with an anteroposterior diameter of less than 10 mm. A statistical analysis was performed using chi-square analysis, nonparametric tests, analysis of variance, and logistic regression. RESULTS: Pain at rest and at night was reported by 68 and 60 patients, respectively, and was more common in younger patients (P = 0.065 and 0.015, respectively). A severe reduction of walking ability (< 0.5 km) was reported by 70 patients. The straight leg raising test results were negative in 70 patients, positive > 60 degrees in 16, positive 30-60 degrees in 14, and positive < 30 degrees in 5. Younger patients had a positive straight leg raising result (P = 0.028, analysis of variance) more often. Reflex disturbances correlated to patient age: Older patients had reflex disturbances more often. There was no correlation between preoperative duration and pain or neurologic disturbances: Patients with longer preoperative duration of symptoms did not demonstrate more severe symptoms. There was a total myelographic block of the spinal canal in 13 patients. The mean value of the antero-posterior diameter in the other patients was 6.8 mm (range, 4-11 mm). In patients younger than 70 years L4-L5 was the site for the most pronounced constriction, whereas L3-L4 was the narrowest site in the older patients. Degenerative spondylolisthesis was found in 32 patients, and they had a more pronounced constriction of the spinal canal (5.6 mm compared with 6.7 mm in those without displacement, P = 0.02). There was a (nonsignificant) tendency toward more walking disturbances in patients with a more pronounced constriction of the spine. There was no correlation between reflex disturbances or extensor hallucis longus weakness and radiographically detected constriction. CONCLUSION: Pain was more intense and positive straight leg raising test results were more common in younger patients, whereas reflex disturbances were more common in the elderly. The vertebral site for the lowest anteroposterior value was higher with higher age. Preoperative duration did not affect the severity of symptoms or signs. Patients with more pronounced stenosis tended to have a more severe reduction of walking ability. There was no correlation between symptoms and signs and radiographically detected constriction.

Aged↗
PubMed1997

A prospective and consecutive study of surgically treated lumbar spinal stenosis. Part II: Five-year follow-up by an independent observer.

STUDY DESIGN: A prospective and consecutive study of surgical results obtained during serial follow-up investigations in patients who underwent surgery for central lumbar spinal stenosis. OBJECTIVES: To evaluate the result after surgical decompression for lumbar spinal stenosis, at regular intervals after surgery, and to correlate these results with values for preoperative parameters; special interest was focused on the results in relation to the degree of constriction of the spinal canal. SUMMARY OF BACKGROUND DATA: The outcome after surgery for spinal stenosis is debatable; long-term follow-up investigations have indicated deterioration with passing time. Results of studies in nonsurgical patients have demonstrated that the symptoms do not progress with time. Results of a meta-analysis of the literature on surgical results have demonstrated a wide variation of outcomes. MATERIAL AND METHODS: In a prospective study, 105 consecutive patients who underwent surgical decompression (laminectomy with facet-preserving technique, but no fusion) were evaluated at follow-up examinations 4 months and 1, 2, and 5 years after surgery. At the follow-up examinations, the patient's opinion on the surgical result was registered, using a four-grade scale. The occurrence of pain at rest and at night was registered, as well as the patient's walking ability. Statistical analysis was performed, relating the surgical results to patient age, gender, preoperative duration of symptoms and radiographically observed constriction as described in Part I of this study. The radiologist was blinded to patient outcome. Logistic regression analysis was performed. RESULTS: During the follow-up period, 19 patients underwent reoperation, consisting of fusion to treat lumbar pain (n = 4), repeat decompression because of progressive stenosis (n = 13), and repairs in response to surgical complications (n = 2). Follow-up results: The result, related to the recurrence of leg symptoms, deteriorated with passing time. Excellent results were reported by 63% to 67% at 4-month and 2-year follow-ups compared with 52% at the 5-year follow-up. There was a correlation between the constriction of the spinal canal and the outcome at all intervals. Patients with an anteroposterior diameter of 6 mm or less at the narrowest site had significantly better results. The logistic regression analysis demonstrated a significant correlation between a severe reduction of the anteroposterior diameter and excellent results and a tendency toward better results in patients with a shorter preoperative duration of symptoms. Improvement of walking ability was also associated with a pronounced constriction of the spinal canal. CONCLUSION: The results after surgical decompression in patients with central spinal stenosis deteriorated with time. There was a significant correlation between good result and pronounced constriction of the spinal canal. Patients with a preoperative duration of symptoms of less than 4 years and patients with no preoperative back pain tended to have better surgical outcomes. The reoperation rate was 18% within 5 years. When surgery for spinal stenosis is contemplated, these prognostic factors should be taken into consideration: The "ideal patient" has a pronounced constriction of the spinal canal, insignificant lower back pain, no concomitant disease affecting walking ability, and a symptom duration of less than 4 years.

Adult↗
PubMed1997

The spondylolytic vertebra and its adjacent segment. Mobility measured before and after posterolateral fusion.

STUDY DESIGN: By using roentgen stereophotogrammetric analysis in six patients having tantalum indicators implanted at a preoperative external fixation test, the mobility in the spondylolytic lumbosacral level and its adjacent segment could be studied before fusion and during the course of postoperative fusion consolidation. OBJECTIVE: To study the mobility effects on the segment adjacent to a lumbar fusion over time from the preoperative situation until fusion healing as defined by roentgen stereophotogrammetric analysis. SUMMARY OF BACKGROUND DATA: In vitro studies indicate that the altered biomechanical situation after lumbar fusion increases the intradiscal pressure and changes the kinematics in the juxtafused segment. METHODS: Six patients with low grade spondylolysisolisthesis were scheduled for fusion of the spondylolytic lumbosacral segment after a preoperative external fixation test. The latter procedure also included implantation of tantalum markers for spinal roentgen stereophotogrammetric analysis. Each patient was examined by roentgen stereophotogrammetric analysis at four separate occasions: before fusion (2 months after removal of the external frame) and 3, 6, and 12 months after surgery. The translatory movements of the L5 vertebra in relation to sacrum and of the L4 vertebra in relation to the L5 vertebra were calculated at each examination. RESULTS: For the juxtafused L4-L5 level, increased and decreased mobility patterns could be identified. Transformation of the preoperative mobility in the lumbosacral segment to the adjacent segment during fusion consolidation was verified in two patients but was not a general phenomenon. CONCLUSION: Fusion of the lumbosacral segment can alter the kinematics of the adjacent segment, redistributing the mobility toward relative hypermobility in the juxtafused segment.

Adult↗
PubMed1997

Posterolateral lumbar fusion using facet joint fixation with biodegradable rods: a pilot study.

Roentgen stereophotogrammetric analysis (RSA) was used to assess whether there is a potential for biodegradable rods crossing the denuded facet joints to increase the stability and healing rate of lumbar posterolateral fusions. Eleven consecutive patients with lumbosacral disc/facet joint degeneration had a posterolateral fusion augmented with 2- or 3.2-mm biodegradable rods passing perpendicularly through the center of the denuded facet joints. The patients were followed-up with RSA in supine and erect positions monthly from the 2nd to the 6th postoperative month, and again 1 year postoperatively. All seven L5-S1 fusions healed. Four cases were stable as defined by RSA within 3 months, two within 6 months, and one within 1 year. One L4-S1 fusion could not be evaluated by RSA. None of the remaining three L4-S1 fusions fully healed. In all three cases 1- to 3-mm intervertebral translations remained at 1 year. None of the 11 fusions showed any radiographic signs of osteolysis around the biodegradable rods. The promising results of this pilot study indicate that posterolateral L5-S1 fusion augmented with transarticular biodegradable rods crossing the denuded facet joints may yield rapid intervertebral stabilization and a high healing rate without any adverse rod effects. This may be due to enhanced initial fusion stabilization and/or increased ossification induced by the rods.

Adult↗
PubMed1996

Clinical characteristics of recurrent sciatica after lumbar discectomy.

STUDY DESIGN: A prospective and consecutive study with preoperative collection of data using a standard protocol for data processing. OBJECTIVES: The frequency of common symptoms and signs was determined in patients with recurrent disc herniation (n = 22), symptomatic postoperative epidural and periradicular fibrosis after a previous lumbar disc excision (n = 18) and compared with the same variables in primary disc herniation (n = 150). The ultimate diagnostic criterion was the finding at surgery. SUMMARY OF BACKGROUND DATA: Surgical treatment of recurrent sciatica after disc excision is rewarding in most cases of recurrent herniation but not in fibrosis and scarring. METHODS: Recorded were pain at rest, at night, and upon coughing. Three categories of analgesic use were collected: 1) none, 2) intermittent, and 3) regular. Walking capacity was determined as more than 5 km, 1-5 km, 0.5-1.0 km, or less than 0.5 km. the straight leg raising test was graded as positive 0 - 1.0 km, or less than 0.5 km. The straight leg raising test was graded as positive 0-30 degrees, positive 30-60 degrees, positive more than 60 degrees, or negative. The results from a standardized neurologic examination were collected. RESULTS: Pain at rest and pain at night were equally common in all three patient groups, although pain upon coughing was more common in disc herniation (primary and recurrent) than in fibrosis, Severe reduction of walking capacity was reported more commonly by patients with dis herniation, whereas regular consumption of analgesics was reported most frequently by patients with fibrosis. CONCLUSION: The symptoms and signs profiles show differences that may be of interest in differential diagnostic considerations after previous lumbar disc surgery.

Adult↗
PubMed1996

Mechanics of the external fixation test in the lumbar spine. A roentgen stereophotogrammetric analysis.

STUDY DESIGN: By implanting tantalum indicators percutaneously during application of pedicular screws, lumbosacral mobility could be studied with roentgen stereophotogrammetric analysis in seven patients having a diagnostic external fixation test. OBJECTIVES: To determine the mechanical effects on the segmental mobility during an external fixation test of the lumbar spine. SUMMARY OF BACKGROUND DATA: External pedicular fixation test of the lumbar spine has been reported a valuable prognostic instrument in fusion for low back pain. METHODS: A Magerl external fixation device was applied in seven patients with low-grade spondylolysis-olisthesis. By using roentgen stereophotogrammetric technique, the intervertebral translations in the lumbosacral segment were determined. Each patient had three separate examinations; with the frame fixed, with the frame loosened, and without frame 6 weeks after screw removal. RESULTS: With the external frame fixed, the sagittal intervertebral translations were significantly reduced, in three cases to a level beneath the accuracy of the measuring method. One patient had the same immobilizing effect even with the frame loosened while for the others loosening of the frame meant regained mobility of the segment. CONCLUSION: The properties of the external fixator give an adequate mechanical basis for the prognostic external fixation test in lumbar fusion.

Adult↗