PubMed Health⌕ Search

Biomedical subjects

B L Sachs

Publications and source records attributed to B L Sachs.

At least 19 recordsLinked to original sources
PubMed2000

Real-time in vivo loading in the lumbar spine: part 1. Interbody implant: load cell design and preliminary results.

STUDY DESIGN: Instrumented interbody implants were placed into the disc space of a motion segment in two baboons. During the animal's activities, implants directly measured in vivo loads in the lumbar spine by telemetry transmitter. OBJECTIVES: Develop and test an interbody implant-load cell and use the implant to measure directly loads imposed on the lumbar spine of the baboon, a semiupright animal. SUMMARY OF BACKGROUND DATA: In vivo forces in the lumbar spine have been estimated using body weight calculations, moment arm models, dynamic chain models, electromyogram measurements, and intervertebral disc pressure measurements. METHODS: An analytical model was used to determine the force-strain relation in a customized interbody implant. After validation by finite element modeling, strain gauges were mounted onto the implant and connected to a telemetry transmitter. Implants were placed surgically into the L4-L5 disc space of skeletally mature baboons and the transmitter in the flank. After surgery, load data were collected from the animals during activities. Radiographs were taken monthly to assess fusion. RESULTS: The implant-load cell is sufficiently sensitive to monitor dynamic changes in strain and load. During extreme activity, highest measurable strain values were indicative of loads in excess of 2.8 times body weight. CONCLUSIONS: The study technique and technology are efficacious for measuring real-time in vivo loads in the spine. Measuring load on an intradiscal implant over the course of healing provides key information about the mechanics of this process. Loads may be used to indicate performance demands on the intervertebral disc and interbody implants for subsequent implant design.

Animals↗
PubMed1997

In vitro simulation. Early results of stereotaxy for pedicle screw placement.

STUDY DESIGN: Frameless stereotaxy with doppler ultrasound and three dimensional computer model registration is assessed in vitro for pedicle screw placement. OBJECTIVE: To identify feasibility of pedicle screw navigation and placement using this technology. SUMMARY OF BACKGROUND DATA: Inaccurate pedicle screw placement can lead to neurovascular injury or suboptimal fixation. Present techniques in pedicle screw placement involve only confirmation of hole orientation. METHOD: Forty-four pedicle screws were placed in lumbosacral models and cadaver specimens. Accuracy was assessed with a computed tomography scan and vertebral cross sectioning. RESULTS: All screws were intrapedicular. Accuracy of anterior cortical fixation was 1.5 mm, with a range of 2.5 mm. CONCLUSION: In vitro frameless stereotaxy is accurate for pedicle screw placement. This technology adds a component of navigation to pedicle screw placement.

Bone Screws↗
PubMed1997

Anterolateral dynamized instrumentation and fusion for unstable thoracolumbar and lumbar burst fractures.

STUDY DESIGN: A retrospective chart review of 36 patients treated with dynamized anterolateral instrumentation and fusion after decompression for thoracolumbar and lumbar burst fractures is presented. OBJECTIVES: To evaluate a device that allows continual bone graft vertebral endplate compression and determine its potential for healing in patients with thoracolumbar and lumbar burst fractures. SUMMARY OF BACKGROUND DATA: Anterior spinal surgery has led to implant adaptations. Such implants have undergone an evolution in hopes of improving the rate of healing and avoiding neurovascular catastrophes. METHODS: Thirty-six patients underwent anterior decompression dynamized instrumentation and fusion for thoracolumbar and lumbar burst fractures. This involved a dual-rod, quadrilateral, cross-linked frame that allows for continual compression but deters rotation and shear stresses. RESULTS: All patients healed solidly without instrumentation failure. An average recovery of 1.3 Frankel grades was recorded. Subsidence of bone graft vertebral endplate was less than in those placed in a trough. CONCLUSIONS: Dynamized load-sharing anterolateral Cotrel-Dubousset instrumentation led to solid bone graft healing without implant failure by allowing continual compression while deterring shear and rotational stresses.

Adult↗
PubMed1997

Amnioscopic endofetal illumination with infrared-guided fiber.

Minimally invasive amnioscopic surgery has several potential advantages over traditional open hysterotomy, including the reduction of the risk of preterm labor and spontaneous abortion. Adequate visibility of the fetal target organ is obligate to the success of in utero procedures. This is a preliminary report on the use of an end-emitting infrared fiber (750 microns; 810-nm wavelength) that allows image fusion with Infravision videocamera systems (Gabriel Medical, Lafayette, LA). Once placed, this fiber can serve as a homing beacon to identify the fetal bladder in the surgical creation of an amnioscopic vesicostomy for the relief of obstructive uropathies. Under general endotracheal halothane anesthesia, amnioscopic access was established in time-dated pregnant ewes using one 3.7-mm and two radially dilating 2-mm to 5-mm trocars. This access allowed the investigation of several methods of intravesicular infrared fiber placement. Ultrasound-guided direct needle puncture is the quickest method of accessing the fetal bladder but is unreliable when the bladder is empty. Accurate placement of the access needle directly over the suprapubic region was accomplished with amnioscopic assistance. The fiber was also placed transurethrally in one female and one male fetus, with subsequent perforation of the female's bladder. Successful infrared bladder illumination was accomplished in all animals. The fusion integration of this camera system allows simultaneous viewing by visible spectrum and near-infrared wavelengths. We believe that this system provides a further degree of safety for amnioscopic procedures.

Animals↗
PubMed1997

Assessment of access strategies for fetoscopic urologic surgery: preliminary results.

Attempted endoscopic fetal interventions have been increasingly reported, given the knowledge that minimizing the trauma to the uterus by a small access portal can allow prolonged amnioscopic-guided surgery. Numerous fetal anomalies have been targeted for these interventions, including congential obstructive uropathies. This preliminary investigation explored innovative access strategies utilizing time-dated pregnant ewes, 95 to 100 days' gestation (term 145 days). Two strategies were specifically investigated: percutaneous, ultrasonographically guided microamnisocopy and ultrasonographically aided, laparoscopically guided amnioscopy. Both strategies provided excellent fetal visibility and were facilitated by the use of small trocars and microlaparoscopic instrumentation, which promoted prolonged amnioscopy with minimal access trauma.

Amnion↗
PubMed1996

Patient outcomes after reoperation on the lumbar spine.

A consecutive series of thirty-nine patients who had had a reoperation of the lumbar spine was followed up for an average of forty-eight months (range, twenty-four to eighty-six months). The patients were evaluated with regard to pain, functional status, and work status. Twenty-eight patients (72 percent) had a successful outcome, as determined by their ability to return to work, their lack of a need for narcotic analgesics, and their satisfaction with the operative results. Factors that were significantly associated with a successful outcome included a younger age (p < 0.02), working outside the home (p < 0.05), an initial period of improvement after the previous (index) operation (p < 0.01), fewer spinal levels operated on previously (p < 0.05), and a revision procedure incorporating anterior interbody arthrodesis (p < 0.02).

Adult↗
PubMed1994

Reported pain during lumbar discography as a function of anular ruptures and disc degeneration. A re-analysis of 833 discograms.

STUDY DESIGN: This re-analysis was based on 833 computed tomography/discograms collected from 306 candidates for back surgery. OBJECTIVES: The goal was to test the hypothesis that outer anular ruptures are the main determinant of the pain of discography. SUMMARY OF BACKGROUND DATA: Previous analyses indicated univariate associations of pain with disc degeneration and anular ruptures. METHODS: If present, pain was classified as "exact", "similar", or "dissimilar" reproduction of the previously experienced pain. For each disc, ruptures and degeneration were separately evaluated by a four-point scale. Multiple logistic regression with random effects was used in the analysis. RESULTS: Outer anular ruptures were the only predictor of the responses "similar" and "exact". General disc degeneration was the only predictor of the response "dissimilar". There was no effect modification due to gender, age, and spinal level. CONCLUSIONS: During discography, the outer anulus appears to be the origin of pain reproduction.

Adult↗
PubMed1994

Objective assessment for exercise treatment on the B-200 isostation as part of work tolerance rehabilitation. A random prospective blind evaluation with comparison control population.

The purpose of this study was to assess repeated exercise on the B-200 Isostation as part of rehabilitation work tolerance for nonsurgical patients with lumbar spine disorders. For a consecutive 7-month period, treatment subjects were randomly assigned according to birth date for participation in two groups: a standard work tolerance program only or standard work tolerance program plus inclusion of exercise on the B-200 Isostation. Each patient had similar referral diagnosis requiring conservative treatment. Treatment groups were compared with a control population of volunteers who had neither back pain nor known underlying spinal pathology. All study patients had objective measurement of range of motion, isometric strength, and velocity of motion, on the B-200 Isostation before treatment and at follow-up 3 weeks after treatment. The data showed no significant difference of percent improvement when comparing patients in either of the randomized assigned treatment groups. There was a higher percentage of improvement for each treatment group as compared with the control individuals, however. Based on our study using the B-200 Isostation, there is little objective justification for including exercise on the B-200 dynametric Isostation as part of the rehabilitation routine for improvement of functional physical capacity.

Analysis of Variance↗
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↗
PubMed1993

Reflex sympathetic dystrophy after operative procedures on the lumbar spine.

Between July 1987 and April 1991, reflex sympathetic dystrophy developed in eleven patients after a posterior operation on the lumbar spine. The average age of the patients was forty-four years (range, twenty-eight to sixty years). The preoperative diagnosis had been lumbar spondylolisthesis or lumbar instability, associated with degenerative disc disease or with osteoarthrosis of a facet joint. Ten patients had posterior stabilization with bilateral arthrodesis and interpedicular fixation, with use of plates or screws; the remaining patient had a posterior hemilaminotomy of the fourth and fifth lumbar vertebrae, partial discectomy, and foraminal decompression of the fifth lumbar-nerve root. After the operation, all patients had burning pain, vasomotor dysfunction, and dystrophic changes in the lower limb and foot; in four patients, the symptoms were bilateral. The symptoms began four days to twenty weeks after the operation. The patients were followed for nine months to four years. Treatment was most successful in four of six patients who had had at least one nerve-block of the sympathetic lumbar trunk in addition to physiotherapy.

Adult↗
PubMed1990

Spinal rehabilitation by work tolerance based on objective physical capacity assessment of dysfunction. A prospective study with control subjects and twelve-month review.

A work tolerance program was used for rehabilitation treatment of 45 patients with spinal dysfunction. Patients entering the treatment group were prospectively evaluated by objective physical capacity assessment (PCA). Treatment patients averaged 4 weeks of three, one half day sessions per week. These patients were compared with a control group of 33 patients who did not participate in the rehabilitation program but were evaluated by PCA. A telephone review of all patients in each group was carried out at 6- and 12-month follow-up. Results demonstrated that 78% of the rehabilitation treatment group were discharged with an improved functional work capacity. Most importantly, at 6-month follow-up, 73.0% of patients in the treatment group were productively working while only 38% of control group patients were actively employed. In addition, 84.4% showed an improvement in spinal range of motion. The subjective pain scale ratings of these treatment patients demonstrated only 44.4% decreased pain, while 51.1% stayed the same, and two patients increased discomfort. Further medical diagnostics or intervention was required in 24.4% of treatment patients. These findings definitely show that a spinal rehabilitation work-tolerance program based on objective measurement will enhance an increased rate of return to productive employment activity. There is poor correlation of subjective pain assessment when compared to objective PCAs. Therefore, recommendations of patients for return-to-productive work should be based pain ratings. When adjusted for nonselection patients, the authors community-based hospital program showed similar results to other programs. The work tolerance and rehabilitation program in Concord, New Hampshire, demonstrated a significant cost-effective approach; being less expensive, less time-consuming, and less psychologically oriented.

Adult↗
PubMed1990

Primary neoplasms of the thoracic and lumbar spine. An analysis of 29 consecutive cases.

Primary osseous neoplasms of the thoracic and lumbar spine are uncommon lesions. Between 1965 and 1982, of 1971 patients with musculoskeletal neoplasms, only 29 (1.5%) had primary osseous tumors in these locations. There were eight children and 21 adults. Back pain was the most common complaint in 25 patients (86%), and neurologic symptoms or deficits were present in 16 patients (55%). All lesions were visible on routine spine roentgenograms, while computed tomography and myelography demonstrated spinal canal encroachment and extradural spinal cord compression in 19 patients (66%). The histologic diagnoses included 11 benign and 18 malignant lesions. Benign lesions occurred predominantly in children and malignant tumors in adults. Treatment was individualized, based on the histologic diagnoses. Twenty-two patients had surgical resection of their lesions. Laminectomy without stabilization and arthrodesis resulted in late instability and neurologic deterioration in three of seven patients (43%) with malignant lesions. Resection and decompression combined with arthrodesis did not predispose to late instability. Twenty-one patients were followed for a mean of 4.1 years (range, two to 14 years). Eight patients died from malignant disease between one month and seven years after diagnosis.

Adolescent↗
PubMed1989

Pain provocation and disc deterioration by age. A CT/discography study in a low-back pain population.

The computed tomography (CT)/discograms and discographic pain provocation reports of 291 clinical patients, 790 discs (mean age, 38; range, 17-79) were collected. The CT/discograms were classified separating anular disruption and degeneration and recording the pain provoked during discography as no pain, dissimilar, similar, or exact reproduction of the patient's clinical pain. Nondegenerated discs usually were found to be painless, and deteriorated discs painful. The proportion of severely degenerated but painless discs increased with age, as did the discs producing dissimilar pain. This may help explain the poor correlation of low-back pain with radiographic degenerative changes reported in previous epidemiologic studies.

Adult↗
PubMed1988

A comparison of CT/discography, pain response and radiographic disc height.

CT/discograms of 107 low-back patients were classified by annular degeneration, annular disruption, and pain response. These parameters were compared with the heights of the corresponding discs. Disc height correlated significantly with degenerative annular changes. Comparison of the painless and exact reproduction groups at the L5-S1 level showed a significant increase in exact pain reproduction in narrow discs compared with normal discs. Discs demonstrating slight degenerative changes were often painful but narrowing was detected only when degeneration increased to moderate or severe levels. Some severely degenerated discs were painless and only part of the severe group was narrow. Measuring disc height is a poor method for detecting early, painful degeneration changes.

Back Pain↗
PubMed1988

Disc deterioration in low-back syndromes. A prospective, multi-center CT/discography study.

Disc deterioration and pain provocation in different low-back pain syndromes was studied using computed tomography (CT) discography. Data were prospectively collected for 300 patients (816 discs). Patients were classified by their pre-discography diagnosis of disc herniation (DH), degenerated disc (DD), lumbar syndrome (LS), lumbar radicular syndrome (LRS), or other. The CT/discograms were classified by discographic pain response, the amount of degeneration and annular disruption. Eighty-two percent of DH patients, 80% of DD, 56% of LS, and 59% of LRS patients had both positive discographic pain provocation and moderate or severe disc deterioration. The study indicates that intradiscal pathology plays a major role in nonspecific low-back pain syndromes.

Back Pain↗
PubMed1987

Dallas discogram description. A new classification of CT/discography in low-back disorders.

A new classification method for CT/discography was developed. The Dallas discogram description (DDD) related five separate categories of information. Degeneration and annular disruption were regarded as separate phenomena. Additionally, provoked pain response, contrast volume, and miscellaneous information were recorded. Discogram findings of 59 patients with low-back and/or leg pain were graded according to the new method and compared with standard methods using routine anteroposterior and lateral discographic images. Findings from routine discography and CT/discography were graded and correlated with myelographic and plain computerized axial tomography (CAT) scans. This study demonstrated that the contrast-enhanced axial view provided by CT/discography served as a useful projection for demonstrating disc pathology. CT/discography analyzed according to DDD offered a more sensitive discriminator of disc degeneration from annular disruption (disc protrusion/leaking). This evaluation can be recommended as the procedure of choice when revision of spine surgery is considered or when there is an equivocal or negative correlation between clinical information and myelography or CAT scan.

Adult↗
PubMed1987

The relationship of pain provocation to lumbar disc deterioration as seen by CT/discography.

The CT/discographic findings from 225 discs in 91 low-back pain patients were compared to the pain provocation during the injection of contrast into the disc. The radiographic appearance of disc deterioration demonstrating disc degeneration and annular disruption of each disc was classified separately using a fourpoint scale: normal, slight, moderate, or severe. Pain reaction to the discogram at each level was recorded as follows: no pain, dissimilar pain, similar pain, or exact reproduction of the patient's clinical pain. This more precise analysis demonstrated a significant relationship between pain and deterioration of discs. The CT/discogram presents an axial view of the disc that allows a subgrouping of disc deterioration that can discriminate between peripheral deterioration (degeneration) and internal deterioration (disruption). The disruption supposedly occurs earlier and is more likely to be the source of exact pain reproduction.

Adult↗