Björn Strömqvist

Randomized Radiostereometric Study Comparing Osteogenic Protein-1 (BMP-7) and Autograft Bone in Human Noninstrumented Posterolateral Lumbar Fusion : 2002 Volvo Award in Clinical Studies

Study Design. Randomized efficacy trial comparing two types of noninstrumented posterolateral fusion between L5 and S1 in patients with L5 spondylolysis and vertebral slip less than 50%, as evaluated by radiostereometric analysis. Objective. To determine whether osteogenic protein-1 (BMP-7) in the OP-1 Implant yields better stabilizing bony fusion than autograft bone. Summary of Background Data. Animal studies of osteoinductive proteins in noninstrumented posterolateral fusions have shown high fusion rates. No similar conclusive study on humans has been performed. Methods. For this study, 20 patients were randomized to fusion with either OP-1 Implant or autograft bone from the iliac crest, 10 in each group. The patients were instructed to keep the trunk straight for 5 months after surgery with the aid of a soft lumbar brace. At surgery 0.8-mm metallic markers were positioned in L5 and the sacrum, enabling radiostereometric follow-up analysis during 1 year. The three-dimensional vertebral movements, as measured by radiostereometric analysis induced by positional change from supine posture to standing and sitting, were calculated with an accuracy of 0.5 to 0.7 mm and 0.5° to 2.0°. Conventional radiography was added. Results. No significant difference was noted between the radiostereometric and radiographic results of fusion with the OP-1 Implant and fusion with autograft bone. There was a significant relation between reduced vertebral movements and better bone formation. No adverse effects of the OP-1 Implant occurred. Persistent minor pain at the iliac crest was noticed in one patient. Conclusions. There was no significant difference between the two fusion versions. Thus, the OP-1 Implant did not yield better stabilizing bony fusion than autograft bone.

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° in 16, positive 30‐60° in 14, and positive <30° 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 anteroposterior 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.

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 spondylolysis‐olisthesis 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.

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.

Intracapsular pressures in undisplaced fractures of the femoral neck

We studied intracapsular pressure in 50 patients with Garden Grade I and II subcapital fractures. Before operation pressures varied from zero to 320 mmHg, 16 patients having an intracapsular pressure of over 80 mmHg. The pressure was increased considerably by medial rotation and decreased by lateral rotation and especially by semi-flexion. From zero to 36 ml of blood was aspirated; the amount did not correlate with the intracapsular pressure. Of 25 patients who were also examined by scintimetry, 13 had reduced uptake at the femoral head before aspiration, and nine of these showed a marked increase in uptake after aspiration. Intracapsular tamponade of the hip may be one reason for the occasional occurrence of segmental collapse of the femoral head after subcapital fracture with minor displacement.

No relationship between epidural fibrosis and sciatica in the lumbar postdiscectomy syndrome : a study with contrast-enhanced magnetic resonance imaging in symptomatic and asymptomatic patients

Study Design. Symptomatic patients were retrospectively analyzed and compared with a control group from an ongoing prospective and consecutive study. Objectives. To determine the presence and extent of epidural fibrosis in patients with and without recurrent sciatic pain after previous lumbar discectomy, contrast-enhanced magnetic resonance images were evaluated and correlated with surgical findings in the symptomatic patients. Recurrent hemia and bony stenosis were ruled out as the probable causative agent, as well as any morphologic explanation other than fibrosis. Summary of Background Data. Repeat surgical results for patients with the lumbar postdiscectomy syndrome with epidural fibrosis alone are often unfavorable. The pathogenic role of epidural fibrosis, however, has not been established. Methods. The magnetic resonance images of eight patients with recurrent or persistent sciatic pain after lumbar discectomy were compared with those of eight asymptomatic patients constituting a control group. All were examined with magnetic resonance imaging on a 0.3 T unit before and after intravenous injection of gadolinium-DTPA, and clinically, 6 months to 4 years after surgery. The symptomatic patients subsequently underwent reoperation. Results. Fourteen patients had focal or diffuse epidural fibrosis around the nerve root and/or the thecal sac at the operated level, whereas the postoperative findings for two patients were “normal,” one in the operated and one in the control group. No difference between the groups regarding mass effect or affection of the nerve roots or thecal sac was noted. At reoperation of the eight symptomatic patients, fibrosis was the only pathologic finding in all cases except one, in which surgery confirmed the normal finding on magnetic resonance imaging. Six of the eight operated patients had recurrent or persistent symptoms within a year of the reoperation. Conclusion. No differences regarding the presence and extent of epidural fibrosis between the symptomatic and asymptomatic patients could be demonstrated with contrast-enhanced magnetic resonance imaging. The role of epidural fibrosis as the causative agent in the lumbar postdiscectomy syndrome is questioned.

Effect of lumbar orthosis on intervertebral mobility. A roentgen stereophotogrammetric analysis

To determine the stabilizing effect of external lumbar supports on the intervertebral mobility in the lower lumbar spine, seven patients with a posterolateral lumbosacral fusion without internal fixation were examined by roentgen stereophotogrammetric analysis in supine and erect positions 1 month after surgery, that is, after soft tissue healing but before fusion consolidation. Each patient was examined without lumber support, with a molded, rigid orthosis and with a canvas corset with molded, plastic posterior support. Neither of the two types of lumber support had any stabilizing effect on the sagittal, vertical, or transverse intervertebral translations. This study using roentgen streophotogrammetric analysis confirms that lumbosacral orthosis has effect by restricting gross motions of the trunk rather than intervertebral mobility in the lumbar spine.

Mobility of the lower lumbar spine after posterolateral fusion determined by roentgen stereophotogrammetric analysis.

To determine the time-table for intervertebral stabilization after posterolateral fusion without osteosynthesis in the lower lumbar spine, 11 patients with no previous spinal surgery and with fusion due to spondylolysis-olisthesis Grade 1 to 2 or lumbar disc disorder/facet joint arthrosis were examined by roentgen stereophotogrammetric analysis (RSA) in supine and erect positions, and by conventional radiography for 1 year after surgery. In eight patients with osseous fusion radiographically, the sagittal and the vertical translations between the fused vertebral segments began to decrease after 3 to 6 months. However, the time for rigid fusion as defined by RSA varied between 3 months and 1 year, and in four patients sagittal/vertical translations of mostly less than 1 mm still persisted at 1 year postoperatively. In three patients with poor fusion radiographically, no rigid fusion as defined by RSA was obtained. Sagittal/vertical translations of 1 to 10 mm persisted at 1 year postoperatively in these patients. The preoperative pain disappeared in all patients except in one who had osseous fusion radiographically but persisting translations after 1 year.

Hook-pin fixation in femoral neck fractures : A two-year follow-up study of 300 cases

In 300 femoral neck fractures treated with hook-pin internal fixation, no perioperative mortality and no deep infection was seen. Eighty-four patients (28%) died within two years of the date of fracture. At two-year follow-up examination, 56 of 300 cases (19%) had developed radiographic healing complications, i.e., redisplacement, nonunion, or segmental femoral head collapse (26% of the survivors). Three of 85 undisplaced fractures (4%) developed segmental collapse (5% of the survivors) while among displaced fractures, radiographic evidence of malhealing was found in 53 of 215 cases (25%; 35% of survivors) at two-year follow-up examination. In the total series, secondary hip arthroplasty was performed in 34 cases (11%). Atraumatic reduction and internal fixation are recommended as primary treatment in femoral neck fractures.

Symptoms and signs in degeneration of the lumbar spine. A prospective, consecutive study of 300 operated patients

In a prospective, consecutive study we determined the frequency of common symptoms and signs in 300 patients with lumbar nerve-root compression syndromes. We compared 100 patients with disc herniation (mean age 43 years), 100 with lataral spinal stenosis (41 years) and 100 with central spinal stenosis (65 years), using a standard protocol of common signs and symptoms. The diagnoses were established by one or more of myelography, CT, MRI and nerve-root block, and all were confirmed at operation. The preoperative duration of symptoms was significantly shorter in patients with disc herniation. Pain at rest, at night, and on coughing was as common in lateral stenosis as in disc herniation, but regular consumption of analgesics was more common in patients with disc herniation. Positive straight-leg-raising tests were more common in disc herniation than in lateral stenosis and were uncommon in central stenosis. Motor disturbances were seen most often in central spinal stenosis, especially patellar reflex changes. Sensory disturbances were most common in patients with complete disc herniation.