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Biomedical subjects

Y S Liao

Publications and source records attributed to Y S Liao.

12 recordsLinked to original sources
PubMed1999

Effect of protein lubrication on the wear properties of materials for prosthetic joints.

The effects of pre-dilution and other modifications of bovine serum lubricants on the wear properties of UHMW polyethylene acetabular cups were evaluated in a hip joint simulator. The wear rate increased, and a nonphysiological type of surface-pitting occurred, when the serum was pre-diluted to 40% or lower concentration. During the wear test, the equilibrium temperature and the precipitation of proteins were substantially greater with zirconia balls than with cobalt-chromium. Protein precipitation, a potential modulator of in vitro wear, was shown to be temperature, concentration, and time-dependent in water-bath tests, which indicated that ball-cup interface temperatures in the simulator must be above 60 degrees C, i.e., well above the bulk lubricant temperature, to account for wear test protein precipitation. Several modifications of serum that were, in part, intended to decrease the tendency for protein precipitation were found to markedly affect the wear properties of the two combinations of materials. In particular, modified serum, which lacked some of the higher molecular weight proteins, produced a much higher wear rate than a control serum with the same initial protein concentration. The results indicated directions for further research to clarify the lubricating properties of serum, and for developing a universal standard test lubricant.

Animals↗
PubMed1999

Video-assisted thoracoscopic surgery to the upper thoracic spine.

BACKGROUND: The standard open technique for exposure of the upper thoracic spine, T1-T4, usually requires a difficult thoracotomy. From November 1, 1995 to June 30, 1997, eight patients underwent video-assisted thoracoscopic spinal surgery in our institute to treat their upper thoracic spinal lesions endoscopically. METHODS: A new approach, the so-called "extended manipulating channel method," was used in this series that allows the combined use of video-assisted thoracoscopy and conventional spinal instruments to enter the chest cavity freely for the procedures. Patients' ages ranged from 44 to 89 years (average, 60 years). Definitive diagnoses included two pyogenic spondylitis and six spinal metastases. Five patients presented initially with myelopathy. RESULTS: There were no deaths or neurologic injuries associated with this technique. The mean surgical time was 3.1 h. The mean duration of chest tube retention was 3.3 days. The mean total blood loss was 1,038 ml, and two patients had a blood loss of more than 2,000 ml owing to bleeding from epidural veins or raw osseous surfaces. Complications included one superficial wound infection and one subcutaneous emphysema that resolved spontaneously. In this series, there was no need of conversion to open thoracotomy for the patients. CONCLUSIONS: The thoracoscopy-assisted spinal technique using the extended manipulating channels, usually 2.5-3.5 cm, allows variable instrument angulations for manipulation. The mean surgical time (3.1 h) was considered no longer than for an open technique for the equivalent anterior procedure. Such an approach can achieve less procedure-related trauma and has proved to be a good alternative to other treatment modalities.

Adult↗
PubMed1998

Analysis of techniques for video-assisted thoracoscopic internal fixation of the spine.

Between November 1, 1995, and January 31, 1996, four separate thoracoscopic spinal fixation surgeries were performed via extended manipulating channels using the so-called three-portal technique. The diagnoses included three spinal metastases and one T11 burst fracture. All patients had myelopathy at presentation. Using the three-portal technique, the conventional spinal instruments and fixation devices could be passed freely through the extended manipulating channels (usually 3-4 cm) into the chest cavity and manipulated by techniques similar to those used in standard open procedures. A reduction-fixation spinal plate with variable screw and plate anchoring angles was successfully inserted in the procedures. The total length of the operation ranged from 3.5 to 5 h (average 4.3 h), and the total blood loss was 1000-2500 ml (average 1500 ml). There were no intraoperative deaths, and no patient showed neurological deterioration following the procedures. On the basis of these results, we believe that the combination of video-assisted thoracoscopy and conventional spinal instruments presented in this report would be an ideal method for performing these procedures. Throughout the operation, only one trocar was employed for introducing the thoracoscope. The thoracoports were used temporarily during tumor tissue retrievals. This technique makes thoracoscopy-assisted spinal fixation simple and easy. It allows greater control of intraoperative vessel bleeding and reduces the number of portals required during the procedure (on average to 3). In addition, the technique reduced the amount of endoscopic materials required for the procedure, thus reducing the cost of treatment.

Adult↗
PubMed1997

Technique of video-assisted thoracoscopic surgery for the spine: new approach.

Although video-assisted thoracoscopy has only recently been applied to treat a variety of thoracic spine lesions, many problems and difficulties are encountered with this technique owing to limited trocar space and lack of suitable endoscopic instruments. Between November 1995 and March 1996, we practiced a new approach for video-assisted thoracoscopic surgery, the "extended manipulating channel method," for treating 18 patients with thoracic spinal lesions endoscopically. The thoracoscopic portals were made larger (usually 3-4 cm) and placed slightly more posterior than usual, which allows use of a combination of conventional spinal instruments and video-assisted thoracoscopy to enter the chest cavity and be manipulated similar to that with techniques used for standard open surgical procedures. In our series the endoscopic spinal procedures included biopsy only (n = 1), thoracic discectomy (n = 1), multilevel anterior discectomy and fusion (n = 1), corpectomy for decompression (n = 4), decompressions and interbody fusions (n = 10), and internal instrumentations (n = 4). Throughout the operation only one trocar was used for introducing the thoracoscope. There were no intraoperative deaths, and no patients showed neurologic deterioration due to the procedures. We conclude that such a technique makes thoracoscopy-assisted spinal surgery simpler and easier and has proved to be an effective, promising procedure. It does not appear to compromise the therapeutic goals set for the patients. The intraoperative vessel bleeding can be easily controlled, and the number of portals for the procedures can be reduced (on average, three portals are enough). Few endoscopic materials were used with our patients, and thus the total economic cost to the patients was reduced.

Adolescent↗
PubMed1997

Video-assisted thoracoscopic treatment of spinal lesions in the thoracolumbar junction.

BACKGROUND: The endoscopic treatment of spinal lesions in the thoracolumbar junction (T11-L2) poses a great challenge to the surgeon. From November 1, 1995 to December 31, 1996, we successfully used a combination of video-assisted thoracoscopy and conventional spinal instruments to treat 38 patients with anterior spinal lesions. Twelve of them had lesions in the thoracolumbar junction. METHODS: The so-called extended manipulating channel method was used to perform vertebral biopsy, discectomy, decompressive corpectomy, interbody fusions, and/or internal fixations in these patients. The size of the thoracoscopic portals was greater than usual in order to allow conventional spinal instruments and a thoracoscope to enter the chest cavity freely and be manipulated by techniques similar to those used in standard open surgical procedures. In this series, the procedures were performed by using either a three-portal approach (2. 5-3.5 cm) or a modified two-portal technique involving a 5-6 cm larger incision and a small one for introducing the scope. RESULTS: None of the operations resulted in injury to the great vessels, internal organs, or spinal cord. The total time for the operation ranged from 1.5 to 4.5 h (average, 3); and the total blood loss ranged from 50 to 3000 cc (average, 1050). One patient was converted to an open procedure due to severe pleural adhesion. Complications included two instances of transient intercostal neuralgia, one superfical wound infection, and one residual pneumothorax. CONCLUSIONS: The video-assisted technique with the extended manipulating channel method presented in this report simplifies thoracoscopic spinal surgery in the thoracolumbar junction and makes it easier. It avoids division of the diaphragm, removal of the rib, and wide spread of the intercostal space, and it allows greater control of intraoperative vessel bleeding. Using this technique, the number of portals required during the procedure can be reduced. In addition, the technique reduces the endoscopic materials required, thus lowering overall cost. It is an effective and promising approach.

Adult↗
PubMed1997

A rare neurological presentation due to ossification of the posterior longitudinal ligament of the thoracic spine and ankylosing spondylitis: case report.

Ossification of the posterior longitudinal ligament (OPLL) may be associated with certain rheumatic conditions including ankylosing spondylitis (AS), diffuse idiopathic skeletal hyperostosis (DISH) or spondylosis. More than 95% of all OPLL are localized at the cervical spine. Herein, we report a case of OPLL at the thoracic spine in an HLA-B27-positive female patient with ankylosing spondylitis. The patient was presented to use with spastic paraparesis. The imaging studies included plain roentgenograms, tomograms, myelo-CT and magnetic resonance imaging (MRI). A continuous rod-like ossification along the posterior aspects of the fourth to sixth thoracic vertebrae with spinal cord compression was noted. The patient underwent a laminectomy from T4 to T6. At the second year follow-up examination, residual upper back soreness and mild left thigh pain were noted. However, the patient had resumed a full daily schedule and could walk freely without any support.

Female↗
PubMed1996

Two-level burst fractures: clinical evaluation and treatment options.

Two-level burst fractures are rare. In a series of 180 surgically treated spinal fracture-dislocations, seven had such injuries, with an incidence of 3.9%. Four had fracture sites without contiguity: C4-T12 (one), L1-L4 (one), L2-L4 (one), and L2-L5 (one); and three with contiguity: T12-L1 (one), L1-L2 (one), and L2-L3 (one). L2 was the most frequently involved site, accounting for four in seven. Falling from height was the most common mechanism of injury, accounting for four in seven. Five in seven patients (71%) sustained multiple injuries. Chest traumas and extremity fractures were the ones most frequently associated. All of these patients had incomplete neurologic deficits at initial presentation. In the four discontiguous bursts, the neurologic levels corresponded to the cephalic ones. Six patients had follow-up periods of more than 2 years. Transpediculate systems were used in five, and at follow-up, two had screw breakages. In this series, the average neurologic recovery was 1.3 grades on the Frankel scale. In conclusion, it is mandatory to have a thorough organ system review when such patients are first seen. Then each fracture site would be judged seperately as either a stable or unstable burst preoperatively. Every effort should be made to treat any unstable segment via anterior, posterior, or combined approaches.

Adolescent↗
PubMed1996

Recurrent spinal stenosis caused by tophaceous gout: a case report and review of literature.

A 57-year-old man with severe gouty arthritis for over 20 years was admitted because of persistent back and leg pain and neurogenic claudication. Lumbar spinal stenosis from the L4 to L5 level was diagnosed after admission and decompressive laminectomy was done. However, about 10 months later, another surgery with laminectomy of L2 and L3 and postero-lateral fusion was performed due to post-laminectomy instability with recurrence of stenosis. The pathology of the resected ligmentum flava had tophi deposition. At the one-year follow-up examination after the second operation, the patient was pain free and had resumed daily activity.

Arthritis, Gouty↗
PubMed1996

Juvenile-onset of Dejerine-Sottas disease in a Taiwanese woman.

Dejerine-Sottas disease is an uncommon hereditary neuropathy which has not been reported in Taiwan. We describe a 57-year-old woman who had slowly progressive weakness in her four limbs since adolescence. None of her close relatives had the disease and no consanguinity was noted. Neurologic examination showed severe weakness and vibratory sensation loss in the four limbs. The tendon reflexes were generally absent. Electrophysiologic studies suggested a systemic myelinopathic process. Light and electron microscopy of the sural nerve biopsy specimens revealed many onion-bulb shapes formed by the Schwann cell processes or basement membranes without any evidence of myelin sheaths around the axons, which are characteristic features of Dejerine-Sottas disease.

Age of Onset↗
PubMed1996

Posterior bow and vanishing line signs in diagnosis of burst fractures of the spine on plain radiographs.

It is not uncommon to misdiagnose a burst fracture as a wedge compression fracture initially on plain film, resulting in a late progressive deformity and neurologic damage. The purpose of this study was to analyze the sensitivity, specificity and positive predictive value of plain radiographs in the diagnosis of thoracic and lumbar burst fractures using the posterior bow (PB) and vanishing line (VL) signs. Seven independent examiners, comprising three chief orthopedic residents, two radiologic third-year residents and two emergency attending physicians (orthopedists), randomly reviewed 26 sets of admission anteroposterior and lateral thoracolumbar spine radiographs taken in association with back injuries. They were asked to decide whether patients had a burst or a wedge compression fracture. All patients had computed tomography (CT) scans for diagnostic confirmation. The overall initial sensitivity using discriminant analysis in the diagnosis of burst fractures was 80%. This increased to 90% after the examiners were requested to use the PB and VL signs. The specificity decreased slightly from 75% to 71%, while the positive predictive value remained at 88%. Overdiagnosis of wedge compression fractures as burst fractures occurred, especially when the quality of the films was not ideal. We conclude that, with careful reading, the PB and VL signs help in identifying burst fractures on the initial plain film evaluation.

Adult↗
PubMed1995

Salmonella psoas abscess--a case report.

The clinical presentation of psoas abscess is often non-specific and insidious that may mislead the diagnosis and treatment. The abscess often extends beyond the retroperitoneum and pelvis before its diagnosis, and leads to serious complications. Many diseases have the similar signs and symptoms and must be ruled out. Computed tomogram is the most useful and reliable diagnostic tool. Only a few cases of salmonella psoas abscess were reported in the literature, and were usually associated with spinal osteomyelitis or septic hip. We present a case of salmonella psoas abscess in a patient with diabetes mellitus. The patient had the history of cholecystitis with sepsis due to salmonella infection 4 years before and cholecystectomy had been done. No associated lesion was found to be associated with the abscess, and we believed the abscess being the result of recurrent bacteremic attack. High index of suspicion, early diagnosis, adequate drainage and effective antibiotic treatment are the key points in managing the disease.

Aged↗