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Biomedical subjects

Y Suezawa

Publications and source records attributed to Y Suezawa.

At least 37 records · Page 2Linked to original sources
PubMed1980

The mechanical response of the neural arch of the lumbosacral vertebra and its clinical significance.

To investigate the effect of mechanical stresses in the aetiology of spondylolisthesis a study of the behaviour of the lumbar spine under load has been carried out. The loading tests on the lumbo-sacral segment, both with and without the dorsal elements present, showed that generally the disc only transmitted axial loads whereas transverse loads are resisted by the dorsal processes. Only after simulating a spina bifida, by splitting the lamina, was it possible to initiate a fracture in the isthmus by means of force applied in the transverse direction. Measurement of the stress behaviour in the neural arch shows that with transverse loading alone the pedicle can be just as heavily stressed as the pars interarticularis. Strain gauge measurements were performed on a macerated fifth lumbar vertebra to determine the manner in which loading forces must act to provide the greatest effect upon the region of the pars interarticularis. This was found to occur with vertical loading of the hyperextended spine. The vulnerability of the vertebra under these conditions was confirmed with further tests upon fresh cadaver specimens when it was found that the pars interarticularis of the fifth lumbar vertebra, when impinged upon by the caudal joint edges of the fourth lumbar vertebra, could be fractured with a vertically applied load of about 200 kp.

Humans↗
PubMed1978

[Dorsal occipito-cerivale spondylodesis with plate fixation of the wire to the occiput (author's transl)].

In occipito-cervical spondylodesis, performed because of instability in this area, there is quite a high incidence of pseudarthrosis. We tried to achieve a biomechanically stable spondylodesis by anchoring the temporary stabilizing wire-loop with a small osteosynthesis plate in the occiput and with a cortical screw in the spinous processus. Our two cases operated by this method showed a favorable result with good reduction. The bone graft consolidated without complications, the wire-loop did not break. This method seems to be less complicated that the fixation with a special plate according to Cabot and Mordent.

Arthrodesis↗
PubMed1978

[Progressive slipping in severe spondylolisthesis-long-term observation (author's transl)].

In total consolidated dorsal fusion it is possible that the decreased intervertebral distance as well as the displacement can increase. 50 patients treated in the period from 1925 till 1977 with a spondylolisthesis of more than 50% have been reviewed. 36 of them were treated by a dorsal fusion, the 14 other patients without operation. Increased displacement was found in 43 cases. This phenomen will be brought about the deflective deformation of the dorsal fusion. Depending on the elasticity bone rebuilding under substinent biomechanical conditions is possible. In the course of time, total intercorporal consolidation leads to a difinitive stability and relief of pain.

Adult↗
PubMed1977

[Secondary intervention after hip prosthesis (author's transl)].

From 1965-1975 in the orthopedical Univ. Clinic Balgrist, Zurich, there were 177 reoperations after total hip prostheses necessary. In 91 replacements the interval between first and second operation was an average of 4.1 years, in 67 prosthesis-removements 2.1 years. The follow-up showed a relationship between bacteriological culture taken before and during operation and clinical results. The decision to change or remove the prostheses should be made on the positive or negative bacteriological results.

Aged↗
PubMedDate not supplied

[Indications for and choice of reintervention in failed back operations].

Is it true that even today, the results of reinterventions after unsuccessful spine surgeries are often unsatisfactory, despite major diagnostic and therapeutic advances in the field of spinal surgery. Based on our observations of cases with failed back surgery syndrome in the Department of Orthopaedic Surgery, the University of Balgrist Zürich, the indications for a reintervention and the choice of the surgical procedure are reported. The use of decompression as re-intervention is successful only in cases where there is an unequivocally demonstrable lack of space for the nervous system due to recurrent hernia or narrow spinal canal. In such cases it may be possible, subject to careful assessment of the criteria, to perform a percutaneous nucleotomy as an alternative to a conventional microsurgical discectomy. Nowadays decompression by means of instrumental spinal fusion is usually indispensable as re-intervention after unsuccessful surgeries.

Adult↗
PubMedDate not supplied

[Complex indications in surgery of the lumbar spinal canal].

Opinions on the treatment of disc herniation are very controversial and the results reported vary, very much indeed. Most often, one decided--and still decides--to excise the disc herniation in conjunction with hemilaminotomy or flavectomy; this method having been carried out from 1974 to 1983 on 598 patients, at the department of Orthopaedic Surgery, Balgrist, of the University of Zurich. A follow-up of over 400 patients has proved to be very informative: whereas very good or good clinical results can be reported in 73.6% of such cases with disc herniation, alone, these not having undergone operation before, similar results were only found in 27.2% of those who had also been suffering from additional causes of lumbalgia like a relatively narrow spinal canal, spondylolisthesis, spondylolysis or nearthrosis for instance. This finding is of paramount importance when attempting to improve the overall results. It is very necessary to separate the complex cases from the "simple" disc herniation ones. At the same time, those patients suffering from lumbalgia due not only to a herniated disc but also to other additional causes arising from alterations to the lumbar spinal canal must be judged and treated differentially. The present follow-up permits conclusions and considerations correspondingly.

Adolescent↗
PubMedDate not supplied

[Percutaneous nucleotomy with discoscopy. 7 years' experience and results].

Percutaneous nucleotomy was first described in 1975 by Hijikata in Japan. We introduced this method since 1979 for the treatment of lumbar disc herniation at the Department of Orthopaedic Surgery, the University of Zürich, Balgrist, improved the original instruments of Hijikata and employ since 1982 various arthroscopes in order to remove nucleus pulposus more accurately and effectively under direct visual control (discoscope). This method was performed between 1979 and 1986 in our clinic in 75 patients with lumbar disc herniation. The clinical result was designated as excellent or good in 48 of 75 patients (65%). The 7 years experiences with this procedure are reported on this paper.

Adult↗