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Biomedical subjects

R Gunzburg

Publications and source records attributed to R Gunzburg.

At least 19 recordsLinked to original sources
PubMed1998

The role of surgery in the management of low back pain.

The main challenge of surgery in the treatment of low back pain lies with the poor knowledge of the aetio-pathogenesis of this symptom. Surgical treatment requires the precise diagnosis of a surgically curable lesion. In low back disorders this research of a precise source of nociception remains elusive even in the presence of radiological abnormalities. Indeed, surgery may not be performed to treat a symptom (low back pain), but an objective condition or disease. Surgical treatment for low back pain is the subject of many controversies, but a certain numbers of attitudes can be (generally) agreed upon in a variety of low back disorders: (i) intervertebral disc herniation; (ii) degenerative spinal disease; (iii) spinal stenosis; (iv) lytic spondylolisthesis. However, there is a wide choice of attitudes, techniques and procedures for each of those indications and numerous conflicting result reports have been published. This chapter will try to present the best available consensus regarding the indications and results of different surgical procedures in spinal disorders. Most of all, physicians should bear in mind that, in spine surgery perhaps more than in other fields, unreasonable patient (and surgeon) expectations will most likely lead to poor outcomes.

Humans↗
PubMed1995

Effects of posterior instrumentation on axial rotation of the lumbar spine: an in vitro biomechanical study.

We tested the hypothesis that instrumentation applied across two levels of the lumbar spine inhibits rotation at these levels and that this inhibition is accompanied by more rotation at the levels above and below. The rotation in the transverse plane of each of the five lumbar vertebrae of 10 cadaveric lumbar spines was produced by dead weights applied to a torsion bar attached at T12. The lumbar spines were first measured without instrumentation being applied. Three different types of instrumentation were then applied in turn across two levels of each lumbar spine: AO internal fixation from L2 to L4, lumbosacral Louis plates from L4 to S1, and Cotrel-Dubousset (CD) pedicular screws and rods from L2 to L4 and then from L4 to S1. For each of these four, a set of measurements of rotation in the transverse plane was taken. The Louis plates allowed less rotation across L4-S1 than CD, although the result was not significant. The AO fixator applied across L2-L4 allowed significantly less rotation across L2-L4 than CD. The AO fixator was compared with the spine with no instrumentation to determine if less rotation across L2-L4 was associated with more rotation across L1-L2 and L4-L5; the differences were significant (p < 0.05).

Biomechanical Phenomena↗
PubMed1994

Tomoscintigraphy of the lumbar spine: prospects and clinical application.

In an in vivo prospective study, we examined the lumbar spine of 18 patients presenting with a first episode of acute low-back pain with single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI). Scintigraphic activity at L2 was considered 100%, and the other levels were quantified in relation to L2. MRI scans were rated for disc signal intensity on T2-weighted images. The results show that an abnormal intervertebral MRI signal corresponds with an abnormal image on tomoscintigraphy. On tomoscintographic profiles, the disappearance of the 'discal dip' corresponds well with degeneration on MRI. Furthermore, a positive MRI at one level appears to influence other levels at which a significantly higher scintigraphic activity was observed. Of patients with acute LBP 50% had a normal disc SPECT; it is concluded that in these cases a non-discal origin for the pain must be sought.

Acute Disease↗
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

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

A cadaveric study comparing discography, magnetic resonance imaging, histology, and mechanical behavior of the human lumbar disc.

The aims of this study were 1) to compare discography and magnetic resonance imaging scanning on cadaver specimens and to correlate these imaging procedures by examining all the discs histologically; and 2) to study the extent to which the amplitude of rotational movement in the neutral and flexed position at a certain level correlates with the morphologic appearance of that disc. Twenty-four human lumbar spines were harvested from cadavers between the ages of 19 and 75 years. Each specimen underwent standard radiography, magnetic resonance imaging scanning, discography, histologic examination, and measurement of axial rotation in a torsion apparatus. For practical reasons, all specimens did not undergo all of the examinations. Not all peripheral anular lesions were detected by discography. Histology showed rim lesions of the anterior anulus in 18% of discs with normal discography. The overall incidence of anterior and posterior anular tears was greater in discs where larger amplitudes of rotation were observed. To which extent the one is a consequence of the other or vice versa is not clear. Magnetic resonance imaging was found to be less specific than discography. However, it must be emphasized that no axial magnetic resonance imaging scans were taken in this study. Discs with significantly decreased amounts of nuclear material (observed at histology) can still produce normal magnetic resonance imaging images. Infolding of the inner layers of the anulus fibrosus (33% anterior, 4% posterior) was a frequently observed feature.

Adult↗
PubMed1991

Axial rotation of the lumbar spine and the effect of flexion. An in vitro and in vivo biomechanical study.

A series of experiments were performed on eight whole, cadaveric lumbar spines and on eight male volunteers to determine whether axial rotation changed with subjects bending forward compared with being in a neutral posture and whether rotation was affected by articular tropism. Kirschner wires were inserted into the spinous processes of the eight cadaveric lumbar spines, and the axial rotation of the wires was measured while the spine was rotated in a torsion apparatus. Similarly, Steinmann pins were inserted into the spinous processes of L3, L4, and L5 of the eight volunteers, and the axial rotation of the pins was measured while the subjects rotated in a torsion apparatus. Axial rotation was found to be less when combined with forward flexion, and articular tropism did not influence the amplitude of rotation.

Adult↗
PubMed1991

Radiologic interpretation of lumbar vertebral rotation.

The different parts of the lumbar pedicle were identified on an anteroposterior (AP) radiograph to determine reliable reference points to be used to quantify vertebral rotation. Standard AP radiographs were taken of dry lumbar vertebrae with 5 degrees increments in rotation in the transverse plane, ranging from 0 degrees to 30 degrees both to left and right. Identical sets of radiographs were taken with radiopaque markers around the middle and in the anterior and posterior parts of the pedicles. The anatomic center of the pedicle was found to lie slightly more lateral than the center of the pedicle halo. The inferior edge of the pedicle corresponded with the anterior part of the pedicle and the superior edge, with the posterior part.

Humans↗
PubMed1991

Biomechanical behavior of the tibiofibular frame in nonunion.

In this paper an in vitro investigation of the biomechanical behavior of the tibiofibular frame in nonunion using electrical extensometry is presented. The intact and untreated nonunited frames are studied as well as three surgical treatments classically used in nonunion: the plating technique, the onlay graft technique and the external fixation according to Ilizarov. The monopodal position with extended knee is considered, and particular attention is paid to the different muscle insertions. The results for the plating and onlay grafting techniques resemble those for the intact frame, whereas the Ilizarov external fixator increases the overall rigidity of the frame. In the untreated nonunited tibiofibular frame, an inversion of the tension and compression areas at the level of the tibia was found. We hypothesize that this phenomenon could be one of the mechanical factors leading to nonunion. Indeed, cyclic stresses in the fracture callus might prevent bony fusion, for the areas healing under compression stresses must become tension areas once the tibia is healed and vice versa.

Biomechanical Phenomena↗
PubMed1990

Lumbar intervertebral disc prolapse in teenage twins. A case report and review of the literature.

We report the cases of teenage twin girls presenting within months of each other with severe symptoms from lumbosacral disc prolapses, requiring laminectomy in one and chemonucleolysis in the other. CT scans showed similarities in spinal configuration, including the presence of disc bulges at the L4-5 level. This suggests a strong hereditary factor in prolapse of intervertebral discs, but a review of the literature showed little information on that aspect.

Adolescent↗
PubMed1989

The value of computerized tomography in determining lumbar facet joint orientation.

The reliability of assessing facet joint obliquity from standard CT scans in the lumbar spine was studied. There was no significant difference in repeated measurements by one single examiner, nor in measurements made by different examiners. Measurement of facet joint obliquity from CT scans made on different occasions was not significantly different either. This reproducibility occurred despite the fact that adjacent CT scans from one joint extremity to the other showed variation in obliquity of about 11%.

Analysis of Variance↗