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Biomedical subjects

O L Osti

Publications and source records attributed to O L Osti.

11 recordsLinked to original sources
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

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

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↗
PubMed1992

Annular tears and disc degeneration in the lumbar spine. A post-mortem study of 135 discs.

We studied 135 lumbar discs from 27 spines removed post-mortem from subjects of an average age of 31.5 years. Defects of the annulus fibrosus were classified as peripheral, circumferential or radiating; the nucleus pulposus as normal, moderately or severely degenerate. Peripheral tears were more frequent in the anterior annulus, except in the L5-S1 disc. Circumferential tears were equally distributed between the anterior and the posterior annulus. Almost all the radiating tears were in the posterior annulus, and closely related to the presence of severe nuclear degeneration. Histology suggested that peripheral tears were due to trauma rather than biochemical degradation, and that they developed independently of nuclear degeneration. The association of peripheral annular lesions with low back pain is uncertain but our study suggests that they may have a role in the pathogenesis of discogenic pain.

Adolescent↗
PubMed1990

1990 Volvo Award in experimental studies. Anulus tears and intervertebral disc degeneration. An experimental study using an animal model.

An animal model was developed to test the hypothesis that discrete peripheral tears within the anulus lead to secondary degenerative changes in other disc components. In 21 adult sheep, a cut was made in the left anterolateral anulus of three randomly selected lumbar discs. The cut was parallel and adjacent to the inferior end-plate, and had a controlled depth of 5 mm. This left the inner third of the anulus and the nucleus pulposus intact and closely reproduced the rim Lear lesion described by Schmorl. Animals were randomly allocated to different groups in relation to the length of time interval between operation and death, varying from 1 to 18 months. At death, the lumbar spine was cut into individual joint units and each disc sectioned into six parasagittal slabs. After observation of the slabs under the dissecting microscope, two of the six slabs, the one containing the anulus lesion and a contralateral, were processed for histology. The results of this study suggest that, despite the great care taken at operation to ensure that the inner anulus was left intact, progressive failure of the inner anulus was seen in all sheep and occurred in the majority of discs between 4 and 12 months after the operation. Although the outermost anulus showed the ability to heal, the defect induced by the cut led initially to deformation and bulging of the collagen bundles, and eventually to inner extension of the tear and complete failure. These findings suggest that discrete tears of the outer anulus may have a role in the formation of concentric clefts and in accelerating the development of radiating clefts. Peripheral tears of the anulus fibrosus therefore may play an important role in the degeneration of the intervertebral joint complex.

Animals↗
PubMed1990

Discitis after discography. The role of prophylactic antibiotics.

Discitis after discography is due to bacterial penetration into the intervertebral disc by a contaminated needle and has an incidence of 1% to 4%. We have examined the prophylactic role of cephazolin administered at the time of discography. An experimental study in sheep using radiographic contrast containing Staphylococcus epidermidis showed that either adding the antibiotic to the intradiscal suspension or giving it intravenously 30 minutes before intradiscal inoculation of bacteria prevented any radiographic, macroscopic or histological signs of discitis; all the intervertebral disc cultures were negative. In a prospective clinical study of 127 consecutive patients having lumbar discography, the injected contrast contained cephazolin 1 mg per ml. None of the patients developed clinical or radiographic signs of discitis. We recommend the use of a suitable broad spectrum antibiotic in a single prophylactic dose whenever the intervertebral disc is entered.

Animals↗
PubMed1989

Iatrogenic discitis: the role of intravenous antibiotics in prevention and treatment. An experimental study.

The role of antibiotics in the treatment of iatrogenic discitis remains controversial. This study was carried out to assess the ability of cephazolin (a first-generation cephalosporin) to penetrate the intervertebral disc and to establish the role of intravenous antibiotics in the prevention and treatment of iatrogenic discitis. Six sheep had 1 g of intravenous antibiotic administered between 30 minutes and 120 minutes before being killed. Two adjacent lumbar intervertebral discs were harvested and assayed for antibiotic concentration. Cephazolin could only be detected in the animals killed at 30 minutes. Intravenous cephazolin was administered 30 minutes before bacterial inoculation in 46 discs of nine sheep. In five animals, the bacterial suspension contained radiographic contrast and, in four sheep, reconstituted chymopapain. No evidence of discitis was found at any level at death. Eight sheep were treated with intravenous cephazolin commencing 1, 2, or 3 weeks after bacterial intradiscal inoculation and for periods of up to 21 days. All discs developed discitis, and the lesions appeared to be similar, irrespective of time between inoculation and the commencement, duration, and dosage of antibiotic therapy. Our study supports the use of a suitable broad-spectrum antibiotic during any surgical procedure that invades the intervertebral disc. Antibiotics, however, are unable to arrest the progression of discitis once it is established

Animals↗
PubMed1987

Fractures and fractures-dislocations of the lumbar spine. A retrospective study of 70 patients.

A retrospective study was undertaken to analyse and compare the results of Harrington instrumentation with postural reduction and nursing in patients with fractures and fracture-dislocations of the lumbar spine. Thirty patients were treated by postural reduction and nursing, and 38 underwent early surgical reduction and internal fixation with Harrington instrumentation, together with a posterior fusion in three patients and an anterior fusion at the level of the fracture in another two patients. External splintage was used in only one patient in the series. At an average follow up of 5.9 years, bony deformity quantified by angulation, displacement and the vertebral wedge index was greater in the conservative group than in the group treated surgically. No significant difference was observed in comparing the rates of neurological recovery in the two groups. At follow up, patients with no symptoms had less severe bony deformity. Loss of fixation of Harrington instrumentation occurred in 46% of patients treated by this method. The incidence of other complications was not significantly different in the two groups. Despite the unacceptably high rate of local complications, Harrington instrumentation achieved better correction of bony deformity than postural reduction and nursing, prevented progression of deformity and decreased the incidence of symptoms at follow up. This study indicates that in these injuries bony deformity can be satisfactorily corrected by early Harrington instrumentation alone, without spinal fusion and bracing, provided an exacting surgical technique is employed.

Adolescent↗
PubMed1987

Discitis after discography.

Infection after intradiscal injections has been recognised as a distinct entity, but discitis after discography has often been attributed to an aseptic process or a chemical reaction to the contrast material. We examined the hypothesis that discitis after discography is always due to infection, and report a clinical review and an experimental study. Part I. We reviewed the case records and radiographs of 432 patients who had undergone lumbar discography. When an 18-gauge needle without a stilette had been used, discitis was diagnosed in 2.7% of 222 patients but stiletted needles and a two-needle technique at each level reduced the incidence to 0.7%. Seven patients with discitis after discography had undergone anterior discectomy and fusion; in them the histopathological findings were of a chronic inflammatory response. Bacteria were isolated from the discs of three of the four patients who had open biopsy less than six weeks from the time of discography. These findings suggest that bacteria were initiators rather than promoters of the response. Part II. Multiple level lumbar discography was carried out in mature sheep, injecting contrast material with or without various concentrations of bacteria. Radiographs were taken and the discs and end-plates were examined histologically and cultured for bacteria at intervals after injection. None of the controls showed any evidence of discitis but all sheep injected with bacteria had typical radiological and histopathological changes by six weeks, though cultures were almost all negative. However, at one and two weeks after injection, but usually not after three weeks, bacteria could be isolated. We suggest that all cases of discitis after discography are initiated by infection, and that a very strict aseptic technique should be used for all injections into intervertebral discs.

Adolescent↗
PubMed1986

Discitis following chemonucleolysis. An experimental study.

Although infection following intradiscal injections has been recognized as a distinct entity, discitis following chemonucleolysis has been often attributed to a chemical reaction from chymopapain. In the first part of this study the effect of chymopapain and Conray 280 on a wide range of bacteria was measured in vitro. Chymopapain was found to have a bactericidal effect on all bacteria tested, which was more pronounced with gram positive organisms, whereas Conray 280 showed very little if any antibacterial effect after 48 hours. The aim of the second part of the study was to test the hypothesis that discitis following intradiscal chymopapain injection is due to infection and not to a chemical reaction. Multiple level lumbar intradiscal injections were carried out in eight mature sheep. Sixteen discs in four sheep were injected with a mixture of reconstituted chymopapain and a Staphylococcus epidermidis suspension. Sixteen discs in another four sheep were injected with reconstituted chymopapain only. All sheep were sacrificed at 6 weeks and the discs and end-plates were examined radiologically, and by histopathology and nuclear material was cultured for bacteria. None of the controls showed any evidence of discitis, whereas all sheep injected with bacteria had typical radiologic and histopathologic changes of discitis. However, in most cases in which end-plate lesions were well established there was no evidence of bacteria at sacrifice. These findings support the opinion that discitis following intradiscal injection is always due to infection introduced by the needle tip.

Animals↗