ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.Lumbar intertransverse process arthrodesis using recombinant human bone morphogenetic protein‐2 was performed in a previously established rabbit model for posterolateral spinal fusion and compared with fusions achieved using autogenous bone graft.Objectives.To qualitatively compare different recombinant human bone morphogenetic protein‐2 dosages and carriers and to determine the efficacy of recombinant human bone morphogenetic protein‐2 as a bone graft substitute to produce lumbar intertransverse process fusion in a validated rabbit model for posterolateral spinal fusion.Summary of Background Data.Autogenous bone was considered the most successful bone graft material used for spinal arthrodesis. Problems with its use may occur in 25‐30% of patients and prompted the search for and investigation of bone graft substitutes and osteoinductive growth factors, such as bone morphogenetic proteins. Recombinant human bone morphogenetic protein‐2 was used successfully in orthotopic sites to generate bone in animal mandibular and long bone defect models.Methods.Posterolateral intertransverse process arthrodeses were performed at L5‐L6 in 56 rabbits using recombinant human bone morphogenetic protein‐2 or autogenous bone graft. Rabbits were killed either 5 weeks later to qualitatively compare fusions achieved using different recombinant human bone morphogenetic protein‐2 dosages and carriers or 4 weeks later to compare the efficacy of recombinant human bone morphogenetic protein‐2 in achieving spinal fusion compared with using autogenous bone graft. Inspection, manual palpation, radiography, histology, and biomechanic testing were used to assess the fusion.Results.All rabbits implanted with recombinant human bone morphogenetic protein‐2 achieved solid spinal fusion by manual palpation and were fused radiographically, whereas only 42% of the autograft control fusions were solid. More mature fusions with greater trabecular bone formation were shown radiographically and histologically in rabbits implanted with the highdose recombinant human bone morphogenetic protein‐2 than with the low‐dose recombinant human bone morphogenetic protein‐2. Fusions achieved using recombinant human bone morphogenetic protein‐2 delivered in the collagen carrier were more remodeled and homogeneous compared with using recombinant human bone morphogenetic protein‐2 delivered in autograft ± collagen carrier. Fusions achieved with recombinant human bone morphogenetic protein‐2 were biomechanically stronger and stiffer than fusions achieved using autogenous bone graft.Conclusions.Recombinant human bone morphogenetic protein‐2 successfully and reliably achieved lumbar intertransverse process fusion in a validated rabbit model for posterolateral spinal fusion. Radiographically and histologically, greater and more rapid bone formation, consolidation, and remodeling were shown with recombinant human bone morphogenetic protein‐2 compared with autogenous bone graft. Fusions achieved with recombinant human bone morphogenetic protein‐2 were biomechanically stronger and stiffer than autograft fusions.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.Infection of rhesus monkeys (Macaca mulatta) with simian immunodeficiency virus (SIV, HIV‐II) was used to study disease transmission in allograft bone. Four allograft bone processing techniques‐fresh, fresh frozen, double freeze‐thaw, and double freeze‐thaw with chemical decontamination‐were evaluated.Objectives.To determine if SIV could be transmitted in allograft bone and if processing techniques could be used to eliminate the potential for disease transmission.Summary of Background Data.Although the risk of HIV transmission in bone allograft was reported to be low, HIV transmission had occurred. In all cases, frozen allograft was used. Donor screening and serologic testing significantly reduced the risk of transmission, although a window of time existed in which an individual was infected but had not seroconverted.Experimental infection of rhesus monkeys with SIV induced a disease syndrome similar to AIDS and provided an ideal model to study disease transmission.Methods.Corticocancellous cylinders were obtained aseptically from SIV‐infected rhesus monkeys. The grafts were randomly placed into one of four processing groups and implanted into noninfected animals. The presence of SIV antibody was monitored by serologic testing. After the monkeys were killed, the graft sites were studied by histology.Results.All animals receiving fresh allograft or allograft bone that had been subjected to either single or double ‐70 C freeze‐thaw cycles became infected with SIV. Animals receiving allograft that had been subjected to a double freeze‐thaw cycle and chemical decontamination were disease‐free after 26 weeks when the animals were killed.Conclusions.The results show that SIV (HIV‐II) can be transmitted in bone allograft procedures. Although freeze‐thaw cycles and lavaging to remove blood elements can reduce the infectivity of a graft, it appears chemical decontamination is necessary to provide a high level of confidence in its safety.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.A prospective study of 19 adolescents and seven adults with idiopathic scoliosis undergoing posterior spinal fusion with segmental spinal instrumentation and a concomitant thoracoplasty had pulmonary function evaluation before surgery and at selected time points up to a minimum 2 years after surgery.Objectives.The objectives were to determine the effects thoracoplasty had on pulmonary function and chest cage dimension changes at a minimum 2‐year follow‐up in idiopathic scoliosis patients.Summary of Background Data.The cosmetic benefits of thoracoplasty on the rib hump deformity are well accepted. The rib resection procedure allowed for procurement of autogenous bone used for the arthrodesis. Short‐ and long‐term pulmonary function evaluation was necessary to determine proper patient selection and any potential sequelae from the rib resection procedure.Methods.All patients had pulmonary function tests consisting of forced vital capacity, forced expiratory volume in 1 second, and total lung capacity performed before surgery and 3 months, 1 year, and 2 years after surgery. Ten adolescents also had computed tomographic scans before and after surgery to evaluate chest cage dimension changes after the procedure.Results.The 3‐month postoperative pulmonary function test values of the 19 adolescents experienced a statistically significant decline, averaging 16% (P < 0.05), however, the mean values for each parameter returned to just slightly below the preoperative value at 2‐years follow‐up. The pulmonary function test values of the seven adults experienced a 27% initial decline 3 months after surgery and a residual 23% decline 2 years after surgery; both values were statistically significant (P < 0.05).Conclusions.We reserve the thoracoplasty procedure for adolescents and adults with preoperative pulmonary function values that will tolerate the morbidity associated with the rib resection. Adolescent patients appear to normalize their pulmonary function tests by 2 years follow‐up, whereas long‐term pulmonary function in the adult patient remains a concern.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.A radiographic evaluation of 100 adult volunteers over age 40 and without a history of significant spinal abnormality was done to determine indices of sagittal spinal alignment.Objectives.To determine the sagittal contours of the spine in a population of adults older than previously reported in the literature and to correlate age and overall sagittal balance to other measures of segmental spinal alignment.Summary of Background Data.Previous studies of sagittal alignment have focused on adolescent and young adult populations before the onset of degenerative changes that may affect sagittal alignment.Methods.Radiographic measurements were collected and subjected to statistical analysis.Results.Mean sagittal vertical axis fell 3.2 ± 3.2 cm behind the front of the sacrum. Total lumbar lordosis (T12‐S1) averaged −64° ± 10°. Lordosis increased incrementally with distal progression through the lumbar spine. Lordosis at L5‐S1 and the position of the apices of the thoracic and lumbar curves were most closely correlated to sagittal vertical axis. Increasing age correlated to a more forward sagittal vertical axis with loss of distal lumbar lordosis but without an increase in thoracic or thoracolumbar kyphosis.Conclusions.The majority of asymptomatic individuals are able to maintain their sagittal alignment despite advancing age. Loss of distal lumbar lordosis is most responsible for sagittal imbalance in those individuals who do not maintain sagittal alignment. Spinal fusion for deformity should take into account the anticipated loss of lordosis that may occur with age.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.A prospective analysis of nutritional status after surgery in 57 spinal reconstructive surgery patients.Objectives.To determine the length of time required for patients to return to their preoperative nutritional baseline and to investigate risk factors for patients with prolonged normalization.Summary of Background Data.The perioperative nutritional status of spinal reconstructive surgery patients appears to be an important parameter of surgical morbidity, complication rates (especially wound healing), patient acceptance, and overall surgical success.Methods.The nutritional parameters of albumin, prealbumin, total protein, transferrin, and the absolute lymphocyte count were investigated before surgery and at various time points after surgery.Results.Forty‐four patients (Group A) with an average 6.4 fusion levels returned to their preoperative baseline nutritional values by 6 weeks after surgery, whereas 13 patients (Group B) with a statistically increased number of fusion levels of 13.8 (P = 0.0009) took 12 weeks or longer to return to their preoperative baseline. Risk factors for prolonged normalization (Group B) included increased total number of fusion levels, especially 10 or more (P < 0.05); patients undergoing circumferential fusions (P < 0.05); and, to a lesser extent, older patients undergoing multiple fusion levels (P = 0.055).Conclusions.These data are important when counseling spinal reconstructive surgery patients before surgery and provides information to those patients who may benefit from perioperative nutritional supplementation.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.Analysis of scoliosis screening in Dublin (1979‐1990) of patients who passed significant levels (25° and 40°) and received orthotic treatment or surgery.Objectives.To reexamine the basis of school scoliosis screening.Summary of Background Data.The United States Preventive Services Task Force questioned the validity of school screening for adolescent idiopathic scoliosis because there is insufficient scientific evidence to justify it.Methods.New entrants (1986‐87) to the screening program were used to test the validity of the screening methods. The total screened population, proportions reaching significant Cobb angles or undergoing treatment, were compared across the time period.Results.The sensitivity of the forward bend test in detecting or predicting 40° scoliosis was 0.83, the specificity was 0.99, and the predictive value was 0.08. The proportion prescribed braces declined significantly (P < 0.01), but there was no significant change in those with scoliosis greater than 24° (0.18%) or 39° (.08%) nor was there a significant change in the numbers needing surgery (.045%).Conclusions.The incidence of significant scoliosis and of surgery is low and independent of changes in bracing policy. The validity of screening to cause significant change in prevalence must be challenged.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.In a prospective study of 90 patients undergoing lumbar pedicle screw instrumentation, 512 screws were tested intraoperatively using electrical stimulation. The accuracy of this technique was verified after surgery by computed tomography.Objectives.Computed tomographic scans taken after surgery were used to evaluate the efficacy of intraoperative screw stimulation and electromyographic monitoring of pedicle screw placement.Summary of Background Data.Previous cadaveric and clinical studies showed the risk of pedicle screw malposition and the inadequate reliability of intraoperative radiographs to identify misplaced screws.Methods.Screws (total, 512) in 90 patients were stimulated intraoperatively, and stimulation threshold was recorded. Computed tomographic scans were taken after surgery to document pedicle screw position. Electromyographic thresholds and computed tomographic data were evaluated independently and compared to assess the accuracy of the electromyographic screw stimulation technique.Results.Intraoperative screw stimulation was extremely accurate in confirming the adequacy of screw position. A stimulation threshold greater than 15 mA provided a 98% confidence that the screw was within the pedicle. In eight of 90 patients (9%), electromyographic monitoring detected a screw malposition that was not identified on lateral radiograph.Conclusions.Screw stimulation monitoring is a valuable and efficacious adjunct to lumbar pedicle screw instrumentation. A stimulation threshold greater than 15 mA reliably indicates adequate screw position. A stimulation threshold between 10 and 15 mA was generally associated with adequate screw position, although exploration of the pedicle is recommended. A stimulation threshold less than 10 mA was associated with a significant cortical perforation in most instances.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.Retrospective review of patient records with recent clinical and radiologic assessment.Objective.To evaluate the long‐term result of anterior and posterior convex epiphysiodesis in the management of congenital scoliosis resulting from fully segmented nonincarcerated hemivertebra.Summary of Background Data.Thirty patients (16 male/14 female patients) were reviewed. Follow‐up was a minimum of 3 years (average, 8 years 10 months; range, 3‐22.5 years). Nineteen patients were skeletally mature, and the mean age of the remaining 11 was 11.75 years.Method.Clinical evaluation and sequential measurements of Cobb angle was made independently by two observers.Results.Compared with preoperative values, the rate of change in Cobb angle was reversed in 23 patients, arrested or slowed in five patients, and unchanged or progressed in two patients. The annual rate of change in Cobb angle was +1.9° before surgery and −1.2° after surgery, a difference of 3.1°. This is highly statistically significant (P < 0.001).Total correction in Cobb angle correlates with age at time of surgery (P < 0.03). The rate of correction in Cobb angle after surgery correlates with the total correction achieved (P < 0.001) and with age at time of surgery (P < 0.05). The greater correction is achieved when surgery is performed at a young age. The preoperative rate of increase in Cobb angle does not correlate with correction (P < 0.76). The site of the hemivertebrae influenced final outcome with best results in the lumbar spine.Conclusion.Combined anterior and posterior convex epiphysiodesis is a reliable method for the correction of deformity resulting from hemivertebrae.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.The transverse plane evolution of the most common idiopathic scoliosis deformities was studied using a cross‐sectional database of 181 patients whose deformities were visualized by precise threedimensional techniques.Objective.The objective was to test the hypothesis that for all common idiopathic scoliosis deformities evolution occurs as a torsion, the apex vertebra translating away from the upper end vertebra and at the same time angulating in a clockwise arc for right apex deformities and a counterclockwise arc for left apex deformities.Summary of Background Data.Perdriolle and Vidal proposed this hypothesis in 1987, which explained observations we had made in 1983 and which was partially supported in thoracic curves in our 1992 study.Methods.Deformities were characterized as single thoracic major, thoracic major and thoracolumbar or lumbar minor, double thoracic and thoracolumbar or lumbar major, and single thoracolumbar or lumbar major curves. The dependent variable studied was the coronal plane regional angular (Cobb) deformity. The independent variables studied were the lateral and anteroposterior translation of the apex vertebra in relation to the upper end vertebra, and the transverse plane translation and angulation of the apex vertebra in relation to the upper end vertebra. For the model or hypothesis to be true, the apex vertebra to upper end vertebra transverse plane translational distance and angular relationship should increase as the Cobb angle increases.Results.In relation to the upper end vertebra, the apex vertebra always translated laterally, almost always was accompanied by transverse plane translation increase, and usually was accompanied by transverse plane angulation increase. Anteroposterior translation was minimal, but for thoracolumbar and lumbar curves it tended to be posterior.Conclusion.The theory that these deformities evolve as torsions, with the apex vertebra translating away from the upper end vertebra and at the same time following a clockwise angular pathway to the upper end vertebra of right apex curves and a counterclockwise angular pathway for left apex curves is supported. Compensatory thoracolumbar and lumbar curves evolve in the same manner as major curves.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID