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Biomedical subjects

R D Fraser

Publications and source records attributed to R D Fraser.

At least 19 recordsLinked to original sources
PubMed2001

Mechanical and pathologic consequences of induced concentric anular tears in an ovine model.

STUDY DESIGN: Relations between induced concentric tears in the sheep disc and the mechanics of the intervertebral joint and vertebral body bone were analyzed. OBJECTIVE: To examine the effect of concentric disc tears on the mechanics of the spine. SUMMARY OF BACKGROUND DATA: Degeneration of the intervertebral disc results in changes to the mechanics and morphology of the spine, but the effect of concentric disc tears is unknown. METHODS: In this study, 48 merino wethers were subjected to surgery, and discs were randomly selected for either a needlestick injury or induction of a concentric tear in the anterior and left anterolateral anulus. Sheep were randomly assigned to groups for killing at 0, 1, 3, 6, 12, and 18 months. From each sheep, two spine segments were mechanically tested: one with a needlestick injury and one with a concentric tear. Macroscopic disc morphology was assessed by three axial slices of the disc. Sagittal bone slices were taken from cranial and caudal vertebral bodies for histologic analysis. RESULTS: Induced concentric tears decrease the stiffness of intact spine segments in left bending and the disc alone in flexion. In all other mechanical tests, the needlestick injury had the same effect as the induced concentric tear. In the isolated disc, the disc stiffness at 6 months was increased for right bending, as compared with the response at 1 month. This was associated with increased anterior lamellar thickening and increased vertebral body bone volume fraction. CONCLUSIONS: Concentric tears and needlestick injury in the anterior anulus lead to mechanical changes in the disc and both anular lamellar thickness and vertebral body bone volume fraction. A needlestick injury through the anulus parallel to the lamellae produces progressive damage.

Animals↗
PubMed2000

Percutaneous endoscopic laser discectomy.

BACKGROUND: The aim of the present paper was to systematically review the literature on percutaneous endoscopic laser discectomy (PELD) with respect to the safety and efficacy of the procedure. Where possible the procedure was compared with open discectomy. METHODS: Studies on PELD were identified using MEDLINE (1984 to December 1999), EMBASE (1974 to December 1999) and Current Contents (1993 to Week 1, 2000). A number of search terms were used: PELD; PLDD (percutaneous laser disc decompression); and laser and (spine or lumbar) and (disc* or disk*). The Cochrane Library was searched from 1966 to issue 4, 1999, using the search terms 'discectomy' or 'discotomy'. Live human studies of patients with lumbar disc prolapses for whom surgery was appropriate were included. Cadaver studies were also included. A surgeon and reviewer independently assessed the retrieved articles for their inclusion in the review. RESULTS: Only 12 papers were identified that related to PELD. The level of evidence for safety and efficacy was low; there were no controlled, blinded or randomized studies. The highest level of evidence came from time series studies. No quantitative analysis could be undertaken for the present review. CONCLUSIONS: Given the extremely low level of evidence available for this procedure it was recommended that the procedure be regarded as experimental until results are available from a controlled clinical trial, ideally with random allocation to an intervention and control group.

Cadaver↗
PubMed2000

The long-term outcome after central cord syndrome: a study of the natural history.

We studied 32 patients with central cord syndrome who were managed conservatively. Six were under 50 years of age (group 1), 16 between 50 and 70 years (group 2) and ten over 70 years (group 3). At the time of discharge all patients in group 1 could walk independently and had good bladder control compared with 11 (69%) and 14 (88%) in group 2 and four (40%) and two (20%) in group 3, respectively. At follow-up after a mean of 8.6 years (4 to 15), ten patients had died leaving 22 in the study. All those in group 1 were alive, could walk independently and had bladder control. In group 2, 13 were alive of whom ten (77%) could walk independently and nine (69%) had bladder control. In group 3 only three were alive of whom only one was independent and none had bladder control. Function at discharge as measured by the ASIA motor scoring system was usually maintained or improved at follow-up, but patients over 70 years of age at injury did poorly.

Activities of Daily Living↗
PubMed1999

Osteoarthrosis of the facet joints resulting from anular rim lesions in sheep lumbar discs.

STUDY DESIGN: Facet joints from sheep lumbar spines were examined for histologic evidence of osteoarthrosis after anular incision. OBJECTIVES: To describe the sequence of changes in facet joints in an animal model of disc degeneration. SUMMARY OF BACKGROUND DATA: There are many studies with results showing a link between facet joint osteoarthrosis and disc degeneration, but the development of osteoarthrosis in facet joints has not been observed in a controlled study of disc degeneration. METHODS: Histologic features of facet joint degeneration were compared with established descriptions of human osteoarthrosis, and the sequence of changes was documented in a controlled prospective study of disc degeneration. RESULTS: Osteoarthrosis in sheep lumbar facet joints is similar to that described in human joints and develops in response to anular injury. Discs degenerate relatively soon after anular incision, but there is a long delay in the appearance of significant changes to the facet joints at the level of anular incision and adjacent levels. CONCLUSIONS: The results shows that facet joints in sheep undergo osteoarthrotic changes in response to disc degeneration and confirm the sheep as a suitable model for the study of degenerative spinal disorders.

Animals↗
PubMed1999

Spinous process osteotomies to facilitate lumbar decompressive surgery.

STUDY DESIGN: A technique for lumbar decompression using spinous process osteotomies is described, and the outcomes are studied prospectively. OBJECTIVE: To describe a technique that affords a wide exposure for decompression while minimizing damage to surrounding tissues, and to analyze the outcomes formally using the technique. SUMMARY OF BACKGROUND DATA: Commonly used techniques of lumbar decompression, which include bilateral takedown of paraspinal musculature and aggressive bony resection, can result in significant iatrogenic sequelae, whereas minimally invasive techniques often provide inadequate visualization and/or decompression. METHOD: Unilateral limited takedown of the multifidus is undertaken, followed by spinous process osteotomies at the involved levels. The spinous processes with the attached interspinous/supraspinous ligaments are then retracted. A complete "trumpeted" decompression is then undertaken. Fifty consecutive patients undergoing the procedure were analyzed prospectively and at follow-up by an independent observer using a validated functional outcome measure, a visual analog pain scale, and a patient satisfaction score. RESULTS: Functional outcome scores improved on average by 47%, pain levels were reduced by 66%, and high satisfaction rates were reported by 83% of patients. CONCLUSIONS: The technique affords excellent visualization and a wide area available for Kerrison use and angulation while minimizing destruction to tissues not directly involved in the pathologic process, including the paraspinal musculature as well as the interspinous/supraspinous ligament complex and facets. Additionally, it minimizes dead space and improves the cosmetic result.

Aged↗
PubMed1999

Short segment fixation of thoracolumbar burst fractures without fusion.

There continues to be controversy surrounding the management of thoracolumbar burst fractures. Numerous methods of fixation have been described for this injury, but to our knowledge, spinal fusion has always been part of the stabilising procedure, whether this involves an anterior or a posterior approach. Apart from an earlier publication from this centre, there have been no reports on the use of internal fixation without fusion for this type of fracture. The aim of the study was to determine the outcome of patients with thoracolumbar burst fractures who were treated with short segment pedicle screw fixation without fusion. This is a retrospective review of 28 consecutive patients who had short segment pedicle screw fixation of thoracolumbar burst fractures without fusion performed between 1990 and 1993. All patients underwent a clinical and radiological assessment by an independent observer. Outcome was measured using the Low Back Outcome Score. The minimum follow-up period was 2 years (mean 3.1 years). Fifty percent of patients achieved an excellent result with the Low Back Outcome Score, while 12% were assessed as good, 20% fair and 16% obtained a poor result. The only significant factor affecting outcome was the influence of a compensation claim (P < 0.05). The implant failure rate (14% of patients) and the clinical outcome was similar to that from series where fusion had been performed in addition to pedicle screw fixation. The results of this study support the view that posterolateral bone grafting is not necessary when managing patients with thoracolumbar burst fractures by short segment pedicle screw fixation.

Adult↗
PubMed1999

Degenerative spondylolisthesis. Developmental or acquired?

Degenerative spondylolisthesis is four times more common in women than in men. Although this gender difference has long been recognised there has been no explanation for it. We have examined the radiographs and CT scans of 118 patients over the age of 55 years and of a control group under the age of 46 years. Our findings confirmed the presence of more sagittally-orientated facet joints in patients with degenerative spondylolisthesis but did not show that the gender difference can be explained by the morphology of the facet joint. Furthermore, we conclude that the increased angle of the facet joint is the result of arthritic remodelling and not the primary cause of degenerative spondylolisthesis. It is more likely to be due to loss of soft-tissue resilience with subsequent failure of the facet joints which are acting as the last restraints to subluxation.

Adult↗
PubMed1998

The Graf ligamentoplasty procedure. Comparison with posterolateral fusion in the management of low back pain.

STUDY DESIGN: A retrospective case-control comparison between the Soft Tissue Stablization System according to Graf and instrumented posterolateral fusion in a consecutive series of patients operated on by a single surgeon. OBJECTIVES: To compare clinical and radiologic outcomes at 1 and 2 years. SUMMARY OF BACKGROUND DATA: Although series have been reported showing encouraging results with the use of the Graf ligamentoplasty for low back pain no comparative data are available on outcome when compared with those in more conventional treatments. METHODS: Eighty-three consecutive patients operated on for low back pain in a single surgeon's practice (TMH) were recalled for clinical and radiologic review. Patients underwent either soft tissue stabilization or posterolateral fusion with pedicle screw instrumentation. Each patient chose between the procedures after advice that the Soft Tissue Stabilization System, although experimental, was a reversible procedure. Independent observers conducted the review at 1 and 2 years. The Low Back Outcome Score was used as an objective measure of outcome. In addition to this, patients underwent computed tomographic assessment of pedicle screw placement. RESULTS: There was no statistically significant difference between groups in age, sex, body weight, symptom duration, previous surgery, dependency on workers' compensation, preoperative diagnosis, smoking habits, and the number of motion segments instrumented. There was a significantly better outcome, when measured by the Low Back Outcome Score in the group of patients managed by posterolateral fusion at 1 year (P = 0.02), although at 2 years the difference was less (P < 0.34). Patients with facet joint-related pain did no better after Soft Tissue Stabilization than did patients of other diagnostic groups. Compensable cases did better at 1 year after fusion (P < 0.003), although again the difference was less marked at 2 years (P = 0.09). There was a trend toward a higher revision rate in the Soft Tissue Stabilization System group (P = 0.11) at 1 year with a statistically significant (P = 0.01) difference apparent at 2 years. Revision after Soft Tissue Stabilization was associated with a poorer outcome, similar to that seen in revision after fusion. Pedicle screw misplacement rates were no different between the two groups and increased in frequency at the more cranial vertebral levels. CONCLUSIONS: Outcome after Soft Tissue Stabilization was associated with a worse outcome at 1 year and a significantly higher revision rate at 2 years. Revision was associated with a poor outcome similar to that seen in revision after fusion.

Adult↗
PubMed1998

Spine update lumbar interbody cages.

Interbody cage devices, used to assist interbody fusion, are rapidly gaining popularity in the surgical management of chronic low back pain. This update provides a structural classification of commonly used devices and assesses them against a set of clearly defined surgical goals, including ability to correct the existing mechanical deformation, ability to provide mechanical stability, ability to provide a suitable environment for arthrodesis, and ability to limit "built-in" morbidity. In addition, the materials used in the devices are examined regarding their biomechanical, biologic, and radiographic characteristics.

Biomechanical Phenomena↗
PubMed1998

Instrumented posterolateral lumbar fusion. Results and comparison with anterior interbody fusion.

STUDY DESIGN: Prospective case series. OBJECTIVES: To assess the results of instrumented posterolateral lumbar fusion, using recognized outcome assessment techniques, to evaluate the correlation between technical and clinical results and the effects of assessment techniques, and to compare the outcome with that of anterior lumbar fusion. SUMMARY OF BACKGROUND DATA: Assessments of lumbar spinal fusion results have frequently been published in forms that render direct comparison difficult and thus have not provided optimal assistance in the selection of a preferred method of treatment. METHODS: One hundred and thirty-five patients with intractable back pain underwent instrumented posterolateral lumbar spinal fusion performed by a single surgeon. Review of results was undertaken by independent observers, using a recognized outcome assessment measure. RESULTS: A solid bony fusion was obtained in 82% of patients. The method of outcome assessment profoundly affected the results; whereas 65% of patients rated themselves significantly improved by the procedure, only 19% achieved a good or excellent result on the Low Back Outcome Score. Patients undergoing a second procedure did not do well, and "salvage" surgery is not recommended. Compensation status was a significant prognostic factor. Psychological distress at review had a profound effect on the disability score and on patient satisfaction ratings. Overall, the results were inferior to those in a similar series treated by anterior lumbar fusion. CONCLUSION: It is recommended that in future studies a recognized outcome score be used and that the analysis specifically include compensation status and psychological distress.

Adult↗
PubMed1998

Calcium pyrophosphate dihydrate deposition in degenerate lumbar discs.

Calcium pyrophosphate dihydrate (CPPD) crystal deposition in lumbar intervertebral discs has been described, but its clinical significance remains unclear. The present study analyzed histological sections of lumbar discs that were obtained from patients undergoing anterior lumbar interbody fusion. Immunohistological staining was undertaken to identify neural elements and blood vessels. Patients with CPPD deposition were compared with a group without CPPD deposition undergoing the same operation. CPPD was found in 15.7% of investigated patients (12.6% of analyzed discs). Deposits were found in areas of the annulus and nucleus showing advanced degeneration. Two patterns were identified: one comprised sharply demarcated rounded deposits, while the other showed diffuse deposition of crystals. There was no association with ingrowth of vascular or neural tissue. Clinical data did not differ significantly in the two groups of patients. However, in all patients with CPPD deposition there was a history of trauma, previous surgery, or both. Isolated CPPD deposition in lumbar intervertebral discs appears to be an incidental finding that is not related to systemic diseases or general arthropathies.

Adult↗
PubMed1998

Mycobacterium avium intracellulare: vertebral osteomyelitis.

A case of vertebral osteomyelitis secondary to Mycobacterium avium intracellulare mimicking Pott's paraplegia is reviewed. To our knowledge, it represents the first published case in a patient without gross immunocompromise. The importance of early differentiation from tuberculous osteomyelitis is stressed as treatment regimens differ and outcomes may be affected.

Aged↗
PubMed1997

Anterior lumbar interbody fusion. A minimum 10-year follow-up.

STUDY DESIGN: One hundred eight patients from a consecutive series of 125 anterior lumbar interbody fusions were invited to take part in a clinical outcome assessment (including plain radiography and magnetic resonance imaging of the lumbosacral spine) more than 10 years after the original surgery. OBJECTIVES: By standardizing the reporting of outcome, to determine whether the duration of patient follow-up influences the outcome of surgery, with particular reference to the effects of compensation and psychological status. SUMMARY OF BACKGROUND DATA: The success rates of lumbar spinal fusion surgery reported in the literature vary widely. The lack of standardization of measures of patient outcome limits the value of study comparisons. Evaluation of the efficacy of spinal fusion is further compounded by the adverse effects of both compensation and psychological disturbance on the reporting of outcome. METHODS: One hundred three patients agreed to take part in a clinical outcome assessment by completing a comprehensive low-back questionnaire that included demographic, compensation, and employment details. Eighty-seven of these cases also agreed to undergo radiographic evaluation and magnetic resonance imaging of the lumbar spine. Subjective assessment of outcome was based on a 10-point analog pain scale as well as patient opinion regarding the success of surgery. A more objective assessment of outcome was made using the Low-Back Outcome Score. Psychological status was determined by combining the Modified Somatic Perception Questionnaire and the Zung Depression Scale. The effects of radiologic fusion, compensation status, psychological status, and reoperation on the various outcome measures were assessed and compared with the results reported in a separate but similar series of patients with a minimum follow-up of 2 years. RESULTS: Seventy-eight percent of patients rated themselves as having "complete relief" or "a good deal of relief," but only 34% fell into the "excellent" or "good" category using the Low-Back Outcome Score. The clinical outcome was not associated with the presence of radiologic fusion and was not influenced by the compensation status. Psychological disturbance at review and reoperation, however, did influence the reporting of outcome and were significantly correlated with the Low-Back Outcome Score. With the exception of the effects of compensation, these results were remarkably similar to the findings in the 2-year study. CONCLUSIONS: The findings of the study suggest that the assessment of outcome of lumbar interbody fusion is strongly compounded by the psychological make-up of the patient and that this effect is maintained in the long term. However, the negative effect of compensation observed at 2 years seems to dissipate with time and becomes insignificant at 10 years.

Adult↗
PubMed1997

The pathologic effects of intrathecal betamethasone.

STUDY DESIGN: The histopathologic effects of the intrathecal injection of betamethasone (Celestone Chronodose; Schering Corporation, Kenilworth, New Jersey) were assessed after the injection of various volumes of the preparation in 20 sheep. OBJECTIVE: To assess the safety of Celestone Chronodose injected into the intrathecal space. SUMMARY OF BACKGROUND DATA: The safety and efficacy of epidural steroid have received considerable attention in the medical literature in recent years. In Australia, reports of possible adverse effects of Depo-Medrol (methylprednisolone), including the complication of arachnoiditis, have been followed by statements from the manufacturers of commonly used steroid preparations recommending they should not be administered epidurally. Previous evidence suggests that arachnoiditis does not result from epidural administration of steroids, but may develop from the intrathecal administration of Depo-Medrol. There are no reports concerning the safety of Celestone Chronodose (beta-methasone). METHODS: Twenty-three adult merino sheep had lumbar punctures performed at the L6-S1 level, and different volumes of Celestone Chronodose or normal saline were injected into the subarachnoid space. The animals were killed after 6 weeks, and the spinal cord, meninges, and nerve roots of the lumbar spine were examined for evidence of pathologic changes. RESULTS: There were no abnormalities demonstrated in three sheep injected with up to 18 ml of normal saline solution. Eleven sheep injected with 1 ml (5.7 mg) of Celestone Chronodose even when repeated at weekly intervals (five sheep, three injections) did not demonstrate pathologic changes. One of six sheep injected with 2 ml of Celestone Chronodose and all of three sheep injected with greater volumes showed histopathologic changes of arachnoiditis. CONCLUSIONS: Given that the volume of cerebrospinal fluid in the sheep is approximately one third of that in humans, this study suggests that small volumes (up to 2 ml) of Celestone Chronodose injected intrathecally in humans are unlikely to cause arachnoiditis, but that the risk of this complication increases substantially with higher doses.

Animals↗
PubMed1997

Foraminal injection for lateral lumbar disc herniation.

Between 1986 and 1995, we treated with foraminal injection of local anaesthetic and steroids 30 patients with severe lumbar radiculopathy secondary to foraminal and extraforaminal disc herniation which had not resolved with rest and non-steroidal anti-inflammatory agents. They were assessed prospectively using standardised forms as well as the Low Back Outcome Score, and were reviewed at an average of 3.4 years (1 to 10) after injection by an independent observer (BKW). Relief of symptoms was obtained in 27 immediately after injection. Three subsequently relapsed, requiring operation, and two were lost to long-term follow-up. Thus 22 of the 28 patients available for long-term follow-up had considerable and sustained relief from their symptoms. Before the onset of symptoms 17 were in employment and, after injection, 13 resumed work, all but two in the same job. The average score before injection was 25 out of a possible 75 points. At follow-up, the overall average score was 54, and in those who had obtained relief of symptoms it had improved to a mean of 61. Based on these findings we recommend foraminal injection of local anaesthetic and steroids as the primary treatment for patients with severe radiculopathy secondary to foraminal or extraforaminal herniation of a lumbar disc.

Activities of Daily Living↗
PubMed1996

The origin and fate of herniated lumbar intervertebral disc tissue.

STUDY DESIGN: In a clinicopathologic study, disc tissue collected from surgery and from cadaveric spines was examined to test an hypothesis about the pathogenesis of herniation. OBJECTIVES: To determine the origin and fate of herniated lumbar intervertebral disc tissue. SUMMARY OF BACKGROUND DATA: Previous studies have ascribed herniated disc tissue to the nucleus, anulus, or endplate, or combinations of the three. One study describes it as newly synthesized fibrocartilage. Regardless of its origin, peripheral neovascularization of disc fragments has been described and may be related to pain symptoms. METHODS: Disc tissue was collected after extrusion and was examined histologically to determine its origin and fate. To test the hypothesis that sequestration results from migration of isolated, degenerate fragments of nucleus pulposus through preexisting tears in the anulus fibrosus, cadaveric lumbar disc were examined in detail. RESULTS: Ninety-eight percent of sequestrations contained some nuclear material indicating that nucleus pulposus is the principal substance extruded from the disc. None contained anulus alone. Although vascular repair was present in 89% of specimens, it did not correlate with several clinical parameters. CONCLUSIONS: The autopsy study confirmed the model of nuclear fragmentation, migration, and extrusion along radiating anular clefts. Neovascularization of extruded fragments bore no relationship with duration of sciatic pain symptoms or clinical outcome.

Adolescent↗