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Biomedical subjects

S I Esses

Publications and source records attributed to S I Esses.

At least 37 records · Page 2Linked to original sources
PubMed1994

In vivo diurnal variation in intervertebral disc volume and morphology.

STUDY DESIGN: Three-dimensional reconstructions of MRI scans measured volume, height, and diameter of intervertebral discs. These measurements were made in vivo. OBJECTIVES: This study documented diurnal change in lumbar disc volume and morphology. The authors studied the pattern of this change over the disc levels that were examined and documented individual differences. SUMMARY OF BACKGROUND DATA: There is a diurnal pattern of standing heights. The majority of this diurnal height change can be accounted for by height loss within the intervertebral disc, which bulges radially with loading. These studies have been performed in vivo. METHODS: Eight normal males were studied using two protocols. In one, the volunteers were in the supine position for 6 hours before MRI scanning. In the other, volunteers spent 4 hours standing and 3 hours sitting before MRI scanning. Three-dimensional MRI scanning was carried out on the L3-4, L4-5, and L5-S1 discs. RESULTS: Volume height and AP diameter of the lumbar intervertebral discs decreased significantly after the protocol of a day's activity. The mean decrease in disc volume at the L3-4 level after standing was 21.1%. At the L4-5 level, it decreased a mean of 18.7%, whereas at the L5-S1 level, there was a 21.6% mean decrease. CONCLUSIONS: The mean simulated diurnal volume decrease in the lower three lumbar discs is 16.2%. Most of the diurnal loss in disc height is due to volume loss. The effect of radial bulging is minimal.

Adult↗
PubMed1993

A histologic study of lumbar pseudarthrosis.

Biopsy specimens were obtained from 35 consecutive patients undergoing pseudarthrosis repair after failed posterior spinal fusions. Biopsy specimens were obtained when possible from the fusion mass, from areas of motion, and from the lumbar facet remnant where identifiable. Tissue found between adjacent bony segments was noted to contain predominantly fibrous tissue often accompanied by signs of local fibrocartilaginous metaplasia. In addition, small fragments of impacted bone, sometimes seen to be undergoing active resorption, also were noted frequently in these areas. The bone adjacent to the areas of motion was sclerotic and poorly organized, containing a mixture of woven and lamellar bone. Interestingly, multiple microtrabecular fracture with appositional new bone formation was a frequently seen feature. All facet joint biopsies were noted to have evidence of degenerative disease. Both cartilage fissuring and significant chondrocyte cloning were noted. Subchondral bony sclerosis was also a consistent feature.

Biopsy↗
PubMed1993

Late infection of spinal instrumentation by hematogenous seeding.

Six cases of late spinal infection following instrumentation are described. In all cases, there was a delay of at least 10 months between surgery and the clinical development of sepsis. In 5 of the 6 cases, a distant focus of infection could be identified. Two patients had active intravenous drug usage, two patients were paraplegic with neurogenic bladders, and one patient had an episode of pyelonephritis secondary to renal calculi two months prior to presentation. In no instance was there any preceding breakdown of overlying skin. This previously unreported phenomenon is an extremely rare but major complication of spinal surgery.

Adolescent↗
PubMed1993

A biomechanical study of odontoid fractures and fracture fixation.

The purpose of this study was to measure the stability of the odontoid process after fracture and subsequent screw fixation. To accomplish this, we mechanically reproduced Type II and Type III odontoid fractures on isolated C2 vertebrae by varying the direction of load. These fractures were subsequently stabilized with a single 3.5 mm screw and retested for multidirectional stability and load to failure. Reduced and instrumented specimens were found to have a stiffness equivalent to one half of that of the unfractured odontoid. Load to failure was also slightly less than one half of the original fracture force (average 160 lb). Screw failure was by a cut-out mechanism in all Type III fractures and by bending of the screw in all Type III fractures. Our findings, in conjunction with the existing literature, strongly suggest that Type III fractures result from extension forces, whereas Type II fractures result from lateral or oblique loading forces. Single screw fixation of an odontoid fracture will provide stability equal to approximately one half that of the unfractured bone.

Aged↗
PubMed1993

The value of facet joint blocks in patient selection for lumbar fusion.

The purpose of this study was to ascertain the correlation between diagnostic facet blocks and treatment outcome, both surgical and nonsurgical. One hundred twenty-six patients who had previously undergone diagnostic facet injections were reviewed. Eighty-two had subsequently undergone lumbar arthrodesis. The rest were treated with a variety of nonoperative modalities. Statistical analysis of accumulated data failed to show any significant correlation between the results of facet blocks and outcome of operative arthrodesis. In addition, statistical analysis failed to show any significant correlation between the facet block results and the outcome of nonoperative treatment. The authors concluded that lumbar facet joint injections cannot be used to determine appropriate patient treatment because they are not predictive of either surgical of nonsurgical success.

Adult↗
PubMed1993

Anterior cervical plate fixation with the titanium hollow screw plate system.

Although anterior cervical plates provide excellent fixation for the anterior column, the potential risk for injury to the spinal cord or soft tissues involved with their use has been the reason they have not gained universal acceptance. Morscher introduced a system that attempts to prevent the migration and loosening of screws by using a cross-split screw head that can be locked into the plate. The secondary advantage of this system is that it eliminates the requirement for posterior cortex purchase and thereby decreases the risk for spinal cord injury. This article reports the authors' experience using the Morscher titanium hollow screw cervical plate system. Forty-two patients in the series underwent anterior cervical arthrodesis for degenerative disease or trauma. The average number of levels fused were two. The fusion rate was 100%. Significant hardware loosening occurred in two patients. There was no iatrogenic injury to the spinal cord or esophagus. In conclusion, the titanium hollow screw cervical plate provides immediate stable fixation with minimal complications. Its use should be considered in the surgical treatment of patients requiring multilevel anterior cervical arthrodesis.

Adult↗
PubMed1993

Complications associated with the technique of pedicle screw fixation. A selected survey of ABS members.

A limited survey analysis of 617 surgical cases in which pedicle screw implants were used was undertaken to ascertain the incidence and variety of associated complications. The different implant systems used included variable spinal plating (n = 249), Edwards (n = 143), and AO fixateur interne (n = 101). The most common intraoperative problem was unrecognized screw misplacement (5.2%). Fracturing of the pedicle during screw insertion and iatrogenic cerebrospinal fluid leak occurred in 4.2% of cases. The postoperative deep infection rate was 4.2%. Transient neuropraxia occurred in 2.4% of cases, and permanent nerve root injury occurred in 2.3% of cases. Previously unreported injury to nerve roots occurred late in the postoperative course in three cases. Screw breakage occurred in 2.9% of cases. All other complications had an incidence of less than 2%. The authors conclude that pedicle screw placement may be associated with significant intraoperative and postoperative complications. This information is of value to surgeons using pedicle implant systems as well as to their patients. Repeat surgery is associated with greater numbers of complications.

Bone Screws↗
PubMed1992

Intraosseous vertebral body pressures.

In an effort to determine the relationship between low-back pain and intraosseous hypertension, in vivo vertebral pressure measurements were performed on 19 patients. A cannulated screw was placed percutaneously into the middle of the vertebral body by a transpedicular route. Pressure measurements were recorded with the patient in various positions. Pressures were greatest in the sitting position, lowest in the prone position, and intermediate in the standing position. A correlation was found between intravertebral body pressure and patient position. Pressures were highest in the positions most commonly associated with low-back pain.

Back Pain↗
PubMed1992

Unilateral facet dislocation of the lumbosacral junction.

Fracture-dislocation of the lumbosacral junction is an extremely rare injury. The authors are aware of only 24 reported cases. Only seven of these were unilateral facet dislocations. In this report, the authors review their experience with four cases of unilateral facet dislocations at the lumbosacral junction. In one of these cases, there was a pre-existing spondylolysis at L5, and the patient sustained a concomitant sacral fracture. From their review, the authors recommend the use of open reduction with internal fixation and lumbosacral fusion as the treatment of choice for this injury.

Adolescent↗
PubMed1992

A new scale for the clinical assessment of spinal cord function.

The systems currently used for grading the severity of neurologic injuries have serious limitations. The authors have developed a neurologic grading system to assess spinal cord function. This is a new, functionally oriented scale which can be used at the bedside and requires no special tests other than those done in a routine clinical neurological examination. This scale includes assessment of motor and sensory function, rectal tone, and bladder control. A major advantage of this scale is that motor function is assessed on a functional rating system. To evaluate the usefulness of this scheme, patients who have been previously entered into a prospective study on the surgical treatment of burst fractures were re-evaluated. A significant number of patients under our new reclassification system were noted to have had significant improvement which had been overlooked using the Frankel Grade system. The authors conclude that their new spinal cord assessment technique has many advantages and suggest that it be used by spinal cord injury centers.

Anal Canal↗
PubMed1992

Indications for lumbar spine fusion in the adult.

More than 20,000 lumbar spine fusions are performed annually in the United States. Results of surgery unfortunately are inconsistent and may reflect unsatisfactory patient selection. Indications for lumbar arthrodesis may arise in degenerative disk disease, deformity, distal extension of previous arthrodesis, trauma, spondylolisthesis, and spinal stenosis (in association with diskectomy or decompression). There are several techniques in the assessment of potential candidates for low lumbar arthrodesis.

Age Factors↗
PubMed1991

Work status after posterior fixation of unstable but neurologically intact burst fractures of thoracolumbar spine.

Thirty nine patients with unstable burst injuries of the thoracolumbar junction who did not suffer neurological injury have been prospectively followed. There were 24 males and 15 females. Five patients were covered under the Workers' Compensation Board (WCB). The average patient age was 34 years (14-66). All patients were stabilised using the AO 'Fixateur Interne' and posterior fusion. The post-operative instrumented sagittal curve averaged six degrees of lordosis (-20 to +20). The length of follow-up averaged 24 months (range 12-24). Pre-operatively 28 patients were employed, 2 were housewives, 6 were students, and 3 were unemployed. At follow-up, all students and housewives had returned to their usual activities. No patient who was initially unemployed had found work. Of the remaining 28 patients who were employed before injury, 23 (82%) had returned to gainful employment, one had returned to school for job retraining, and 5 had not returned to work. Of the 23 patients who had returned to work, 5 returned to lighter duties, and 18 returned to their original occupation. Only 2 of the 5 WCB-covered patients did not return to work. Most neurologically intact patients undergoing surgery for unstable bursting injuries of the thoracolumbar spine can return to work.

Adolescent↗
PubMed1991

Acquisition of lytic spondylolisthesis in the adult.

Two adult patients are described with documented progression from a normally aligned spine to a lytic spondylolisthesis. In neither patient was the time of the pars fracture determined. Both patients complain of back pain with mild radicular symptoms.

Adult↗
PubMed1991

Operative treatment of spinal fractures with the AO internal fixator.

A multicentered prospective trial to investigate the usefulness of the AO spinal internal fixator for the treatment of thoracolumbar fractures and fracture-dislocations was undertaken. This pedicle screw-rod system was effective in stabilizing a variety of unstable fracture patterns. It was effective in decompressing the canal of retropulsed bony fragments associated with burst fractures. By the use of this implant, sagittal plane deformity was easily corrected.

Adult↗
PubMed1991

Translaminar facet joint screw fixation for lumbar and lumbosacral fusion. A clinical and biomechanical study.

Various systems of supplementing bone grafts with internal fixation in the lumbosacral spine have been used in an effort to improve fusion rates. This study reports biomechanical data of cyclic loading cadaveric spines instrumented with translaminar facet screws as well as early clinical results on this technique. Static loading tests comparing uninstrumented and instrumented spinal motion units show that a ninefold increase in flexion load is necessary for constant displacement after facet screw fixation. Repetitive loading tests show only a small decrease in stiffness of instrumented segments even after 5,000 cycles. To date, 35 patients have undergone fusion by this technique as performed by one surgeon. After excluding Workers' Compensation cases and cases with less than 2 years follow-up, there were 18 cases available for review. Twelve of these 18 cases were two-level fusions. Ten patients underwent concomitant discectomy or nerve root decompression. There were no cases of iatrogenic neurologic injury or pseudoarthrosis. It is concluded that translaminar facet screws have a sound biomechanical basis and are a valuable addition to lumbar fusion procedures.

Biomechanical Phenomena↗
PubMed1991

Surgical anatomy of the sacrum. A guide for rational screw fixation.

Anterior sacral anatomy was studied to allow safe sacral screw placement. The study included 27 bony sacra. Intrapelvic dissections were performed. Cadaveric specimens were dissected and photographed. The position and angulation of the first sacral foramen was extremely variable. After the position of the L5 root, sacral roots, and iliac vessels, was considered, safe posterior sacral screw implantation could be assured through placement above the level of the first sacral foramen directed medially toward the promontory, parallel to the superior sacral end-plate. Complications of indiscriminate screw placement included L5-root damage, iliac vein penetration, and intractable perineal pain due to sacral root injury. Preoperative computed tomography with the scanner gantry tilted to parallel the superior sacral end-plate defined the great vessels, neural foramens, inclination of the superior sacral end-plate, and prominence of the posterior ileum. Surgical accuracy was evaluated after surgery with computed tomography.

Bone Screws↗
PubMed1991

Screw fixation of odontoid fractures and nonunions.

Surgical treatment of odontoid fractures has usually been carried out by C1-2 arthrodesis rather than by fracture fixation. An alternative treatment of compression screw fixation was used to treat selected acute odontoid fractures and nonunions. Ten patients were operated on. A variety of lag-screw types were used to compress and secure the fracture. Screw placement was considered excellent in five cases; in four, the screw tip protruded through the posterosuperior cortex of the dens by 1-3 mm. One patient died as a result of multiple injuries 2 days after surgery. In all other cases, including four cases of odontoid pseudarthroses, the fractures achieved solid union. It was concluded that screw fixation can be used for the successful treatment of selected odontoid fractures and nonunions.

Adult↗