The effect of varied electrical current densities on lumbar spinal fusions in dogs.

BACKGROUND CONTEXT: The use of electrical stimulation has been shown to increase the rate of successful spinal fusions. It is possible that increasing the current density of these stimulators may increase the speed and success rate of these fusions. PURPOSE: This study evaluated the effects of varied current densities on the speed and success rate of spinal fusion in dogs. STUDY DESIGN/SETTING: Three different current densities (0.83 microA/cm, 4 microA/cm and 10 microA/cm) were used to stimulate spinal fusions in a canine model over a 12-week period. OUTCOME MEASURES: Radiographic and histologic assessments were used to determine the degree of facet fusions at each time period. METHODS: Fifteen dogs underwent spinal facet fusion bilaterally at the level of L1-2 and L4-5. Each fusion site was electrically stimulated using one of three current densities. At 6, 9 and 12 weeks, the specimens were evaluated using high-resolution radiography and routine histology. The fusion masses were graded and then statistically evaluated. RESULTS: The results demonstrate a dose response of fusion mass scores to increasing current density. The highest current density (10 microA/cm) demonstrated a statistically higher fusion scores than the lowest currently density (0.83 microA/cm) at 6 weeks and statistically greater than both the middle (4 microA/cm) and lowest (0.83 microA/cm) current densities at 9 weeks. No differences were noted at 12 weeks, because all groups showed complete fusion. CONCLUSIONS: This controlled study suggests that speed of fusion may be further improved by increasing the current density of the electrical stimulation.

Extraspinal bone and soft-tissue tumors as a cause of sciatica. Clinical diagnosis and recommendations: analysis of 32 cases.

STUDY DESIGN: Between 1982 and 1997, the authors treated 32 patients with sciatica who subsequently were found to have a tumor along the extraspinal course of the sciatic nerve. SUMMARY OF BACKGROUND DATA: Extraspinal compression of the sciatic nerve by a tumor is a rare cause of sciatica. Signs and symptoms overlap those of the more common causes of sciatica (i.e., herniated disc and spinal stenosis). OBJECTIVE: To characterize the unique clinical presentation of these patients and to formulate guidelines that may lead to early diagnosis. METHODS: All pertinent clinical data and studies were reviewed retrospectively, and standard demographic data were collected for analysis. RESULTS: These patients typically sought treatment for an insidious onset of sciatic pain that was constant, progressive, and unresponsive to change in position or bed rest. The mean time to final diagnosis was 11.9 months (median, 6 months). Seventeen patients were able to locate their pain to a specific point along the extraspinal course of the sciatic pain, and a mass was noted in 13 patients. Eighteen of these tumors were in the pelvis, 10 in the thigh, and 4 in the popliteal fossa and calf. CONCLUSIONS: A high index of clinical suspicion is the key to early diagnosis of bone or soft-tissue tumors as a cause of sciatica; special attention should be given to pain pattern, physical examination of the entire course of the sciatic nerve, and selection of proper imaging studies. Routine anteroposterior plain radiography of the pelvis as part of the initial imaging screening process is recommended.

Spine update. The use of adjunctive electrical stimulation to enhance the healing of spine fusions.

The use of electrical stimulation as an adjunct to enhance lumbar spinal fusion continues to gain popularity. The different types of electrical stimulation and their varying effects on posterior and anterior spinal fusion are discussed. The selection of an electrical stimulation device should be based on the clinical and experimental evidence of efficacy.

Lumbar-sacral radiculopathy secondary to intraspinal synovial cyst.

OBJECTIVE: The presentation of a patient with acute low back pain and distal radiation to the lower extremities is often attributed to a herniated nucleus pulposus (NHP). The purpose of this report is to illustrate how an intraspinal lumbar synovial cyst can have a similar presentation. CASE PRESENTATION: A 52-year-old man presented with low back pain with left lower extremity weakness and distal radiation. An electrodiagnostic evaluation was consistent with lumbar-sacral radiculopathy. Computed tomography and magnetic resonance imaging showed a synovial cyst of the L4-5 facet joint. INTERVENTION: The patient underwent a L4-L5 laminotomy, synovial cyst excision, and decompression of the L5 nerve root. RESULTS: There were no postoperative complications. The patient had residual left lower extremity numbness but gradually regained the strength of his left lower extremity. Intraspinal synovial cyst can mimic the clinical pattern of NHP. CONCLUSION: An intraspinal lumbar synovial cyst can present with symptoms of nerve root compression. Given the presentation of lumbar-sacral radicular symptoms such as radiating pain, muscle weakness, and numbness, surgical excision of the lumbar synovial cyst remains the definitive treatment of choice.

The effect of electromagnetic pulsing on posterior lumbar spinal fusions in dogs.

This study evaluated the effect of pulsed electromagnetic fields (PEMF) on the healing of lumbar spinal fusions. Bilateral posterior facet fusions were performed at L1-2 and L4-5 in 24 adult mongrel dogs. After surgery, eight animals were stimulated with a pulse burst type signal (PEMF) for 30 minutes a day, and eight animals were stimulated with the same PEMF for 60 minutes a day. The remaining eight animals received no active PEMF stimulation and served as controls. Four animals from each group were euthanatized at 6 and 12 weeks, and the facet fusions were evaluated using high resolution radiographs and routine histology. No statistical difference in the radiographic or histologic appearance of the fusion mass could be detected between the stimulated and control groups at either 6 or 12 weeks. The results of this study suggest that PEMF stimulation had no effect on the healing of the primary posterior spinal fusions in this controlled experimental canine model.

Surgical disc excision.

For the athlete, whether recreational or professional, limited surgical discectomy has been a predictable and highly successful procedure, enabling those individuals to return to their preinjury status relatively quickly. With proper patient selection, patients will be able to return to their athletic endeavors with much more reliability than with any of the other currently available surgical alternatives to limited surgical discectomy.

Percutaneous diskectomy.

Automated percutaneous diskectomy and manual percutaneous diskectomy (PCD) have gained recent popularity as alternatives to traditional surgical diskectomy or microdiskectomy. Initial reports of morbidity seem low. The rates of infection, and neurologic and vascular complications appear comparable or less than the morbidity associated with surgical diskectomy or microdiskectomy. However, inconsistent reports of the efficacy of PCD may cause more concern about overuse than about the morbidity.

Effects of spinal flexion and extension exercises on low-back pain and spinal mobility in chronic mechanical low-back pain patients.

It has been estimated that one fourth to one half of all patients treated in physical therapy clinics suffer from low-back pain. The purpose of this study was to compare the effects of spinal flexion (Group I) and extension (Group II) exercises on low-back pain severity and thoracolumbar spinal mobility in chronic mechanical low-back pain patients. Both groups had significantly less low-back pain after treatment (P less than .10). There was no significant difference, however, between the spinal flexion and extension exercises in reduction of low-back pain severity. The results indicated a significant difference between the groups in increasing the sagittal mobility (P less than .10). The results did not indicate any significant difference between and within groups in increasing the coronal and transverse mobility of the thoracolumbar spine. Either the spinal flexion or extension exercises could be used to reduce chronic mechanical low-back pain severity, but the flexion exercises had an advantage in increasing the sagittal mobility within a short period of time.

A multicenter analysis of percutaneous discectomy.

This study was performed to evaluate a group of patients undergoing percutaneous discectomy. All patients had a single level unilateral L4-5 or L5-S1 disc herniation documented on either computer tomographic (CT) scan, myelogram, and/or magnetic resonance imaging (MRI). Average follow-up after percutaneous discectomy was 16.8 months (range, 2-46 months). The average hospitalization time was 1.7 days (range, 1-5 days). Only 21 patients (55%) were able to return to work after the procedure. Thirteen patients ultimately underwent surgical discectomy for continued symptoms after the procedure. The additional 4 patients did not undergo surgical discectomy and never returned to work. Of those 25 percutaneous discectomy patients who did not undergo surgical discectomy, there was significantly more pain, residual weakness, and numbness compared with the patients undergoing surgical discectomy. The results of this study clearly indicate that percutaneous discectomy does not appear to be as predictable or successful a treatment modality as surgical discectomy.

The efficacy of direct current electrical stimulation to enhance canine spinal fusions.

A prospective experimental study was devised to examine the effect of direct current electrical stimulation on the healing of lumbar spinal fusions. Twelve mongrel dogs had posterior facet fusion bilaterally at L1-L2 and L4-L5. A direct current electrical stimulator was placed through each facet fusion. One-half of the electrodes were functional, while the remainder served as controls. Two animals were killed at two and four weeks, and four animals were killed at six and 12 weeks, postoperatively. Each facet fusion was evaluated using high-resolution roentgenograms and routine histology. In the two-, four-, and six-week specimens, there was little difference in the roentgenographic or histologic appearance of the control and stimulated fusions. However, by 12 weeks, all eight stimulated facet joints showed roentgenographic and histologic evidence of solid bony fusion, but none of the eight control facet joints demonstrated osseous bridging of the fusion site. The results of this study suggest that direct current electrical stimulation appears to enhance the bony union of facet fusions in the canine lumbar spine.

Automated percutaneous discectomy: a prospective multi-institutional study.

A prospective multi-institutional study was carried out to evaluate automated percutaneous discectomy in the treatment of lumbar disc herniations. Of the 327 patients who prospectively met the study criteria and were followed for longer than 1 year, 75.2% were successfully treated. When patients (n = 168) who prospectively did not meet the study criteria were treated, the success rate was 49.4%. One case of discitis was reported; otherwise, no other serious complications were noted, and specifically no vascular or nerve damage was encountered. This study indicates that automated percutaneous discectomy can be used successfully to treat lumbar disc herniations with minimal morbidity and emphasizes the need for proper patient selection.

The psychological impact of idiopathic scoliosis on the adolescent female. A preliminary multi-center study.

Seventy-two female idiopathic scoliosis patients, ages 12 to 16, who were receiving either no treatment/observation, the Scolitron, a brace, or who had undergone surgery were tested to determine the psychological impact of scoliosis. Mothers of the patients also served as subjects. A normal group of adolescents served as control subjects. Results showed that all groups were less likely to feel that their health status was due to chance than the controls. No other psychological differences were found between treatment groups, which contradicts previous reports of greater psychological distress among brace patients as compared with Scolitron (TM) patients. It was found that mothers' attitudes toward their children's illnesses were strongly and positively related to their children's attitudes toward their illnesses, and that these attitudes were strongly correlated with psychological distress. These findings underscore the need to consider the parent-child relationship when treating the adolescent patient.

Histochemistry and morphology of erector spinae muscle in lumbar disc herniation.

The purpose of this study was to detect any changes in the erector spinae muscles in patients undergoing surgery for lumbar disc herniation (LDH) and to analyze which factors (sex, age, the level and site of disc protrusion, and duration of symptoms) would be related to these changes. The percentage of mean area of the type I fibers was significantly larger in males and in the older age group (P less than 0.05), due to the decreasing size of type IIa and IIb fibers. Patients with LDH have: 1) angulated and selective atrophy of type II fibers with a higher type IIb/IIa ratio; 2) with increasing age and duration of symptoms, more marked atrophy of type II fibers; and 3) other unspecific pathologic changes.

Long-term strength assessment of postoperative diskectomy patients.

A test battery was used to measure abdominal and back muscle strength and endurance in 20 patients at least 1 year after surgical diskectomy. There were ten men and ten women. Data on isometric and isokinetic performance were compared with previously reported normal values. The data showed that every strength parameter tested except male isokinetic flexion strength showed at least a 30% decrease when compared with normal values. Compared with strength data on these same patients immediately after surgery, a 2-tailed Student t test demonstrated a significant difference only in male isokinetic strength (P less than 0.10) and in female isokinetic strength (P less than 0.05). No other difference was found in isometric strength or endurance compared with data obtained from these patients 4 to 6 weeks postoperatively. From these data, it is obvious that more intensive physical therapy is necessary to improve postoperative strength in patients undergoing surgical diskectomy. These data allow for the design of specific isometric, isokinetic, and endurance rehabilitation programs for the postoperative diskectomy patient.

A database of isoinertial trunk strength tests against three resistance levels in sagittal, frontal, and transverse planes in normal male subjects.

Spatial joint complexes, such as the spine, require multiaxial systems to adequately assess their functional capacity. The B200 Isostation (Isotechnologies, Inc., Carrboro, North Carolina) is a triaxial system that has three hydraulic pumps under control of an IBM-XT. The transducers measure the torque, angular position, and velocity for all axes simultaneously. There is no isoinertial data base available for strength at different resistances in the sagittal, coronal, and transverse planes. A normal data base for dynamic performance against resistances equal to 30%, 50%, and 70% of the maximum isometric strength of trunk muscles in all three planes was established.

Limited surgical discectomy and microdiscectomy. A clinical comparison.

This study was performed in an attempt to determine if there was any clinical or cost benefit of microdiscectomy over surgical discectomy. Each patient was asked to rate his pain or neurologic deficit on a scale from 1 to 10 (1 = no pain or deficit and 10 = the most severe pain or deficit). Thirty patients underwent microdiscectomy. Average preoperative back pain was rated 8.03 and leg pain 8.53. Preoperative numbness was rated 5.29 and weakness 5.38. The median time off work preoperatively was 4 weeks. The mean hospitalization was 2 days, and a postoperative median of 8 weeks for returning to work. Average follow-up was 17.4 months. Mean back pain was 1.8, with 57% having no back pain at follow-up. Mean leg pain at follow-up was 1.3, with 67% having no leg pain. Numbness was rated 0.97, with 85% having none at follow-up. Weakness was rated 1.4, with 76% having none at follow-up. Thirty-four patients underwent surgical discectomy. Average preoperative back pain was rated 7.56 and leg pain 9.32. Preoperative numbness was rated 6.94 and weakness 5.88. The median time off work preoperatively was 6 weeks. The mean hospitalization was 7 days, and a median of 7 weeks postoperative before returning to work. Average follow-up was 18.5 months. The mean pain rating for back pain was 1.09, with 74% having no back pain at follow-up. The average leg pain was 1.09, with 74% having no leg pain at follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

1988 Volvo award in biomechanics. The triaxial coupling of torque generation of trunk muscles during isometric exertions and the effect of fatiguing isoinertial movements on the motor output and movement patterns.

Previous studies have shown that reduction of precise motor control accompanies local muscular fatigue. The effects of isodynamic fatiguing of flexion and extension trunk movements on the movement patterns and the motor output of the trunk were investigated. Twenty male subjects with no history of low-back pain for the past 6 months volunteered for the study. A triaxial dynamometer was used that simultaneously provided measurement of torque, angular position and velocity of each axis. Resistances were set independently for each axis by an interfaced computer. The subjects performed trunk flexion and extension movement against a sagittal plane resistance equal to 70% of their maximum isometric extension strength in the upright position. The minimum resistances in the coronal and transverse planes were set up at 7 Newton meters. The subjects were asked to perform trunk movement as quickly and as accurately as possible while exerting the maximum efforts until exhaustion. Analysis of variance, the MANOVA procedure with a repeated measure design, was performed among the selected parameters of the first, middle and last three repetition cycles. The selected parameters are the trunk motor output and movement patterns; the total angular excursion, range of motion, maximum and average torque and angular velocity of the trunk. All the selected parameters were significantly reduced in the sagittal plane. Subjects displayed significantly less motor control and greater range of motion in the coronal and transverse planes in performing the primary task of flexion and extension. The reduction in the functional capacity of the primary muscles performing the required task is compensated by secondary muscle groups and the spinal structure is loaded in a more injury prone pattern, as identified by finite element models. In addition it is suggested that the fatigued muscles would be less able to compensate any perturbation in the load or position of the trunk. The repetitive loading results in a weakening of the viscoelastic passive elements of the spineless structure. The loss of ability to protect these weakened passive elements makes the spine susceptible to industrial and recreational injuries.