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Biomedical subjects

R D Fraser

Publications and source records attributed to R D Fraser.

At least 55 records · Page 3Linked to original sources
PubMed1995

Magnetic resonance imaging findings 10 years after treatment for lumbar disc herniation.

STUDY DESIGN: Fifty-six patients with lumbar disc herniation who had participated in a double-blind study comparing chymopapain with saline were invited to undergo a magnetic resonance imaging assessment of the lumbosacral spine more than 10 years later. OBJECTIVE: The aim of this study was to assess the long-term morphologic changes after treatment of disc herniation by chemonucleolysis and laminectomy and to compare these findings with the natural history of the disorder. SUMMARY OF BACKGROUND DATA: There is little information on the effects of different treatment methods for lumbar disc herniation on the long-term morphologic changes in the disc. METHODS: Of the original 56 patients, 39 were entered into the study: 12 had been treated by saline injection alone, 14 by chemonucleolysis alone, and 13 had subsequently required laminectomy for a failed intradiscal injection. Each sequence of magnetic resonance images was examined by a radiologist who was unaware of the treatment given. The signal strength was assessed on T2-weighted images in the sagittal plane and disc morphology on T1- and T2-weighted sagittal and T1-weighted axial images. RESULTS: The signal of the treated disc was absent in all cases in each group. Thirty-seven percent of patients were found to have a persistent herniated disc and the incidence was similar in all three treatment groups. The presence or absence of herniation at 10 years had no significant bearing on a successful outcome. CONCLUSION: The findings of this study indicate that long-term improvement of a patient's symptoms after treatment of disc herniation may occur with or without resolution of the hernia. This and the similar morphologic findings in the different groups is consistent with the 10-year clinical results after the treatment of disc herniation reported by Weber.

Adult↗
PubMed1995

Magnetic resonance imaging assessment of disc degeneration 10 years after anterior lumbar interbody fusion.

STUDY DESIGN: One-hundred-eight patients from a consecutive series of 125 anterior lumbar interbody fusions were invited to participate in a radiographic and magnetic resonance imaging assessment more than 10 years after the original surgery. OBJECTIVE: The aim of this study was to determine the long-term incidence of disc degeneration adjacent to an anterior interbody fusion and to determine whether this was influenced by the length of the fusion. SUMMARY OF BACKGROUND DATA: Biomechanical studies in human cadaver spines support the view that fusion in the lumbar spine is likely to be associated with an increased incidence of degeneration at adjacent levels, but there is little reliable information on the incidence of juxtafusion degeneration from the few long-term studies of lumbar spine fusion reported in the literature. METHODS: Eighty-seven patients agreed to take part in the study, but in six cases the magnetic resonance imaging procedure had to be abandoned. Of the 81 patients who underwent both radiographic assessment and magnetic resonance imaging scanning, preoperative discography had demonstrated a normal disc above the level of the fusion in 52. This group of patients formed the basis of this report. Each sequence of magnetic resonance imaging films was examined by one radiologist. The signal strength was assessed on T2-weighted images in the sagittal plane and disc morphology was assessed on T1- and T2-weighted sagittal and T1-weighted axial images. Fusion status was assessed on the plain films and magnetic resonance imaging. RESULTS: The incidence of a normal adjacent intervertebral disc in cases of solid fusions to the sacrum was 68%. This was not influenced by the length of the fusion. CONCLUSION: The findings of this study suggest that degeneration after an anterior lumbar interbody fusion is determined more by individual characteristics than by the fusion itself.

Adult↗
PubMed1994

Does plate fixation prevent disc degeneration after a lateral anulus tear?

STUDY DESIGN: The sheep model was used to investigate the development of disc degeneration after outer anular tearing. OBJECTIVES: The authors determined whether plate fixation promotes healing of peripheral anular tears and thereby minimizes disc degeneration. SUMMARY OF BACKGROUND DATA: A limited outer anular tear (similar to the rim lesion) in the sheep lumbar disc causes progressive and irreversible degeneration within 6 months. Incomplete healing of the tear may result from continued movement in the vicinity of the lesion. METHODS: In 15 sheep, a cut 4 x 10 mm was made in the lateral anulus of two nonadjacent lumbar discs, and a metal plate was fixed across one. Three sheep were killed immediately, and the remainder were killed after 6 months for histologic examination. RESULTS: There were no significant differences in propagation of the cut through the inner anulus, extent of healing, or extent of nuclear degeneration, between plated and nonplated motion segments after 6 months. Vascularization of the cartilage endplate was significantly increased on the operated side (P < 0.01), but remained unchanged on the nonoperated side. CONCLUSIONS: Disc degeneration was not prevented by this method of plate fixation, despite similar but limited healing of the outer anulus tear in both plated and nonplated levels.

Animals↗
PubMed1994

Assessment of spinal cord blood flow and function in sheep after anterolateral cervical interbody fusion in the presence of cord damage.

The safety of an anterolateral cervical fusion, which facilitates stabilization without sacrifice of the anterior longitudinal ligament, recently has been brought into question. The purpose of this study was to assess the effect of an anterolateral cervical fusion on spinal cord blood flow and motor and sensory-evoked potentials in the presence of an incomplete spinal cord injury. In 12 sheep, a spinal cord injury was produced by the rapid inflation of an extradural balloon catheter; six of the animals had a cervical fusion. There was no significant difference in spinal cord blood flow or evoked potential responses obtained from the sheep that had an anterolateral cervical fusion, compared with the sheep that did not. Based on these results, it seems unlikely that this surgery has an adverse effect on recovery from spinal cord injury in the absence of operative mishap.

Animals↗
PubMed1994

Anterior lumbar fusion: results, assessment techniques and prognostic factors.

One hundred and fifty-one patients underwent anterior interbody lumbar spinal fusion for intractable back pain. A solid bony fusion was obtained in 76%. The method of outcome assessment profoundly affected the results; whereas 68% of patients rated themselves as significantly improved by the procedure, only 40% achieved a good or excellent result on the more objective low-back outcome score. Patients who underwent a second procedure did not do well, and "salvage" surgery is not recommended. Posterior distraction instrumentation neither increased the rate of union nor improved the final results. The rate of fusion was influenced by the presence of a compensation claim. Compensation status and psychological disturbance at presentation were significant prognostic factors. Psychological disturbance at review had a profound effect on the outcome and patient satisfaction ratings. It is recommended that future studies employ a recognised outcome score and that the analysis specifically includes compensation status and psychological disturbance.

Adult↗
PubMed1994

Aetiology, diagnosis and treatment of low back pain.

A total of 274 patients complaining of low back pain following injury was reviewed. Impact injuries were associated with soft-tissue strain, which was seen less often after twisting injuries. Twisting injuries were associated with disc prolapse more often than falls. Discogenic pain followed lifting injuries more often than jerking injuries. Slipping and jerking injuries were associated with poor outcomes, but the diagnosis was of no prognostic significance. The response to treatment was markedly influenced by the presence of a compensation claim. Only educational classes could be shown to have a significant effect on outcome.

Female↗
PubMed1994

Anterior lumbar fusion. A comparison of noncompensation patients with compensation patients.

One hundred fifty-one patients had an anterior interbody lumbar spinal fusion for intractable back pain. A solid bony fusion was obtained in 76% of the patients. Of patients unemployed before surgery, 50% had returned to work at review. Sixty-eight percent of patients rated themselves as significantly improved by the procedure. Posterior distraction instrumentation neither increased the rate of union nor improved the final results. Compensation status and psychological disturbance at presentation were significant prognostic factors. Psychological disturbance at review had a profound effect on the outcome and patient satisfaction ratings. It is recommended that in future studies compensation status and psychological disturbances are explicitly included in the outcome statistics.

Adolescent↗
PubMed1993

Keratin intermediate filament structure. Crosslinking studies yield quantitative information on molecular dimensions and mechanism of assembly.

One of the major obstacles to solving the full three-dimensional structure of keratin intermediate filaments (KIF) is the determination of the exact mode(s) of alignment of nearest-neighbor molecules; this in turn requires precise information of the lengths of the non-alpha-helical linker segments within the coiled-coil alpha-helical heterodimer molecule. In this study, we have induced lysine-lysine and cysteine-cysteine crosslinks between keratin intermediate filament molecules in small assembly-competent oligomers, isolated them and then characterized the natures and locations of the crosslinks. Of more than 100 found, 21 quantitatively major crosslinks were used to obtain the relative axial alignments of rod domain segments by least-squares fitting methods. Three dominant modes of alignment were found. In each case the molecules are antiparallel with the first involving molecules in approximate register (stagger = -0.2 nm), the second involving molecules staggered so as to bring the 1B segments into approximate alignment (stagger = -16.1 nm), and the third involving molecules staggered so as to bring the 2B segments into approximate alignment (stagger = 28.2 nm). In addition, the data enable quantitative estimates to be made for the first time of the lengths of the non-coiled-coil segments (L1 = 2.5 nm, L12 = 1.6 nm, L2 = 0.8 nm), and the total length of the rod domain (46.0 nm). Alignment of molecules according to these parameters permits construction of a two-dimensional surface lattice which displays a 1.6 nm (10 or 11 residue) overlap between similarly directed molecules. Together, the data predict six important overlapping sequence regions that recur about 16 times per 46 nm of filament length. Interestingly, synthetic peptides corresponding to these sequences, singly or in combination, significantly interfere with keratin filament structural integrity. These results thus represent the most significant set of structural constraints for KIF yet available and provide insights into how disease-causing mutations disrupt filaments and their organization in cells.

Amino Acid Sequence↗
PubMed1993

An experimental study comparing percutaneous discectomy with chemonucleolysis.

The aim of this study was to assess the macroscopic and microscopic reaction of the intervertebral disc to discectomy with the Automated Nucleotome (Surgical Dynamics, San Leandro, CA), and to compare this with simple trephining of the annulus and with chemonucleolysis. In eight adult sheep, two of four adjacent lumbar discs were randomly incised using the trephine of the Automated Nucleotome, while the remaining levels underwent nuclear excision with the Automated Nucleotome probe. Another four sheep underwent chemonucleolysis at three adjacent lumbar levels. All animals were killed at 6 weeks. The discs that had undergone trephining alone and those treated with the Automated Nucleotome probe had almost identical radiographic and macroscopic changes and showed similarities on microscopic examination. Macroscopically, these discs did not differ from control levels, whereas those treated with chymopapain showed marked changes with a reduction of both nuclear and annular volume. The results of this study suggest that any therapeutic effect of percutaneous discectomy with the Automated Nucleotome is likely to be attributable to the perforation of the annulus alone with the removal of small amounts of nuclear material contributing little, or nothing, to the claimed benefits of the procedure.

Animals↗
PubMed1992

Economic impact of HIV infection and coronary heart disease in immigrants to Canada.

OBJECTIVE: To compare the direct health care costs of illnesses associated with the human immunodeficiency virus (HIV) and of coronary heart disease (CHD) in immigrants to Canada. DESIGN: Comparative cost analysis. PARTICIPANTS: All people who immigrated to Canada in 1988. The numbers with HIV infection and CHD were estimated from country-specific HIV seroprevalence data and national CHD mortality statistics and data from the Framingham study. Health care costs, projected over the 10 years after immigration, were calculated on the basis of data from the Hospital Medical Records Institute and provincial fee schedules. RESULTS: Of the 161,929 immigrants in 1988, 484 were estimated to be HIV positive. The total cost of treatment of HIV-related illnesses from 1989 to 1998 (discounted at 3%) would be $18.5 million: $17.1 million would be spent on the outpatient and inpatient care of the HIV-positive immigrants, $1.0 million on care of the subsequently infected sexual partners and $0.4 million on care of the HIV-positive children born to seropositive immigrant women. In comparison, CHD would develop in 2558 immigrants during the same 10-year period. The total CHD costs would be $21.6 million: $8.4 million would be spent on treating myocardial infarction, $3.2 million on coronary artery bypass grafting, $1.6 million on pacemaker insertion and $8.4 million on treating other CHD events. CONCLUSIONS: The economic impact of HIV infection in immigrants to Canada is similar to that of CHD. This comparison identifies an important shortcoming in current immigration policy: economic considerations can be arbitrarily applied to certain diseases, thereby discriminating against specific groups of immigrants.

Adult↗
PubMed1992

A longitudinal study of the matrix changes induced in the intervertebral disc by surgical damage to the annulus fibrosus.

A 5 x 5-mm anterolateral incision was made in the annulus fibrosus (AF) of lumbar discs of 16 sheep; four animals of similar age not operated on were used as controls. The experimental animals were sacrificed 2, 4, 6, 8, 12, and 18 months postoperatively (PO), and the incised and adjacent lumbar discs were collected. Discs were dissected into four zones: AF (zones 1 and 2) and nucleus pulposus (NP) (zones 3 and 4) corresponding to the half of the AF in which the cut was made and its opposite half, and the complementary halves of the NP. Each zone was analyzed for moisture, proteoglycan (PG), collagen, and noncollagenous protein (NCP) content. The PG extractability, aggregation, and hydrodynamic size were also examined. The NP of injured discs showed a significant loss of PGs and collagen 8 months PO, but NCP levels increased. In the incised discs, PG aggregation initially declined but recovered to within control values 6-8 months PO. The NP of discs adjacent to the incised disc also showed time-dependent changes in matrix components that included loss of collagen and PG; however, the AF matrix remained essentially uneffected. Double immunodiffusion studies indicated that a sizeable proportion of the NCPs present in the injured discs (but not the adjacent lumbar discs) were derived from serum.

Animals↗
PubMed1992

Role of the capsulo-ligamentous structures in rotation and combined flexion-rotation of the lumbar spine.

We carried out experiments on whole cadaveric lumbar spines in order to determine the role that each of the capsulo-ligamentous structures play in axial rotation in the neutral position and in the flexed position. Eight specimens were first tested intact, then after division of all the apophyseal joint capsules between L1 and the sacrum. Another five specimens were also first tested intact, then after division of the supra- and interspinous ligaments and yellow ligament, and finally after cutting the posterior longitudinal ligament and posterior annulus at each level as well. The results show that there is considerable variation in the axial rotation of the lumbar vertebrae within the same spine and across different spines. The apophyseal joint capsules limit rotation both in neutral and flexed positions. In flexion, the amplitude of rotation in the lumbar spine is reduced. Of the capsulo-ligamentous structures, it is the posterior annulus and the posterior longitudinal ligament that seem to play the more important role in limiting axial rotation while the spine is flexed.

Adult↗
PubMed1992

Assessment of outcome in patients with low-back pain.

The Low-Back Outcome Score has been devised as a new and accurate rating system for patients with low-back pain. Thirteen factors, such as pain, employment, sporting ability, rest required, and activities of daily living, were included; subjective opinion was excluded. Pain and active pursuits were weighted. Presentation of the score as a questionnaire, excluding examination findings, eliminated both interobserver variation and observer variation with time. The score was applied retrospectively in a follow-up study of conservatively treated patients and was found to be more comprehensive and more discriminating than the Oswestry Disability Score, the Waddell Disability Rating, or the Waddell Physical Impairment Rating. The Low-Back Outcome Score is recommended for further evaluation in future prospective studies in low-back pain.

Back Pain↗
PubMed1992

Chymopapain. A 10-year, double-blind study.

Sixty patients with sciatica from lumbar intervertebral disc herniation were entered into a double-blind study. Following a randomized schedule, 30 patients were treated with intradiscal chymopapain and 30 patients with intradiscal normal saline. At 10 years, with the patients still unaware of the treatment given, 80% of the chymopapain patients regarded the injection to be successful, compared with 34% for the saline group (P = 0.0006). Laminectomy was required in 20% of the chymopapain patients, compared with 47% of the saline patients (P = 0.028). Seventy-seven percent of the chymopapain group was assessed by a blinded independent observer to be at least moderately improved, compared with 38% for the saline group (P = 0.004). The results of this double-blind study at 10 years demonstrate a sustained therapeutic effect of chymopapain in the treatment of patients with sciatica from lumbar intervertebral disc prolapse.

Adult↗
PubMed1992

Changes in endplate vascularity after an outer anulus tear in the sheep.

In 31 2-year-old sheep, a 5-mm deep cut was made parallel to the end plates in the left anterolateral anulus fibrosus of 3 randomly selected lumbar intervertebral discs. At 2 months, the area of the end plate occupied by blood vessels on the left (operated) side had increased significantly (P less than 0.05) in the cranial end plate to 9.94%, and to 9.39% in the caudal end plate, compared with nonoperated values of 5.17% (cranial) and 5.87% (caudal). One year after operation, these elevated values had diminished significantly (P less than 0.05) to 7.92% (cranial) and 7.13% (caudal), and continued to decline progressively to 7.48% (cranial) and 6.88% (caudal) by 2 years. In contrast, no significant differences were found on the right (nonoperated) side of the discs. Thus, there was an early proliferation of vascular channels in the end plate in the vicinity of the experimental anular lesion, but not on the nonoperated side of the same disc. Thereafter, the end plate vascularity progressively diminished toward a normal level.

Animals↗
PubMed1992

A modified muscle-splitting approach to the lumbosacral spine.

A modification of a previously reported extraperitoneal approach to the lumbosacral spine is described. The external oblique muscle is split in line with its fibers. The anterior and posterior layers of the rectus sheath are divided vertically medial to the semilunaris without splitting the internal oblique and underlying transversalis abdominus muscles. This allows an extensile retroperitoneal approach suitable for exposure of both the mid-lumbar and lumbosacral spine. There have been no complications of this approach with its use in over 50 patients undergoing anterior lumbar interbody fusion.

Abdominal Muscles↗
PubMed1992

MRI and discography of annular tears and intervertebral disc degeneration. A prospective clinical comparison.

We attempted to correlate the findings of MRI and discography in patients with low back pain, examining 108 lumbar intervertebral discs in 33 consecutive patients. MRI results were assessed from the intensity and shape of the signal obtained from the central part of the disc. Discography was classified according to the pattern of contrast material, the pressure accepted and the pain reproduced. All discs which were abnormal on MRI had altered patterns on discography, but 18 of the 60 discs with normal MRI had abnormal discograms. Of 39 asymptomatic discs, 33 had normal MRI signals and 24 had normal discograms. None of the 15 discs showing severe degeneration on MRI sustained high levels of intradiscal pressure, but only six of the 60 discs giving normal MRI had low pressure. With current techniques, discography is more accurate than MRI for the detection of annular pathology: a normal MRI does not exclude significant changes in the peripheral structure of the intervertebral disc which can produce low back pain.

Adult↗