Degeneration of non-fused segments after floating lumbar fusion

Degeneration of the disc or discs between two fused spinal segments has been termed "floating disc disease". The purpose of this retrospective study was to show the radiological evolution of the floating disc(s) and the relationship between floating disc degeneration and segmental lordosis, lumbar lordosis and pelvic incidence. Twenty patients, with a mean age of 49.9 years, with symptomatic lumbar degenerative disc disease or low grade spondylolisthesis, who failed non-operative treatment and underwent fusion of 2 or more noncontiguous spinal segments, were included in this study. The radiographs of the floating discs were graded with the modified Gore System. The mean follow-up was 4.2 years. Forty-seven levels were fused and 27 floating discs were studied (13 single, 7 double). Five out of 27 floating discs (18%), in 4 patients, progressively degenerated. None of the floating discs degenerated more than two radiographic grades and none needed additional surgery. Postoperatively, 3 out of 5 degenerated floating discs had decreased segmental lordosis, while the other two had no change; this difference was not significant (p = 0.08). Neither was there any significant correlation between floating disc degeneration and lumbar lordosis L1-S1 (p > 0.10) or pelvic incidence (p > 0.10). This study shows that the effect of floating fusion on floating discs is the same as the effect of a contiguous fusion on adjacent discs.     

Laparoscopic gastric bypass at a large academic medical center: lessons learned from the first 1000 cases

Bariatric surgery is an effective and durable treatment for morbid obesity in properly selected patients. Surgical outcomes and patient management methods should routinely be reviewed to improve patient care and maintain long-term effectiveness of the bariatric operation. Over a 5-year period, 1096 laparoscopic Roux-en-Y gastric bypass operations were performed at our institution. A comprehensive prospective database was maintained, which included data for comorbidities, operative techniques, perioperative management, complications, and follow up. Many practice patterns such as the omission of routine preoperative sleep apnea testing and biliary ultrasounds remained constant and were validated by the outcomes measured. Several changes, however, were implemented based on outcomes analyses, including antecolic placement of the roux limb, a pars flaccida approach to the creation of the gastric pouch, longer alimentary limbs in superobese patients, and a selective approach to postoperative upper gastrointestinal imaging. Postoperative weight regain and inability to maintain long-term follow up in a significant per cent of patients were two identified and ongoing problems. Maintenance of a bariatric patient database is essential with its routine review resulting in changes to practice patterns and operative techniques. An effective method for long-term patient follow up remains elusive and may contribute to postoperative weight regain in some patients.     

Biomechanical evaluation of paracoccygeal transsacral fixation

STUDY DESIGN: This is a biomechanical study using human cadaveric lumbar spine. OBJECTIVE: To evaluate the biomechanics of paracoccygeal transsacral rod fixation. SUMMARY OF BACKGROUND DATA: Various types of transsacral fixation either by posterior and paracoccygeal approaches have been described in the literature. The biomechanical advantage of transsacral rod fixation is the preservation of supporting structures at L5-S1 level. No biomechanical data on human cadavers have been reported in the literature. The aim of this study is to evaluate the biomechanics of the transsacral rod fixation. METHODS: Six fresh human cadaveric L5-S1 motion segments (mean age 67.5 y; range 46 to 82 y ) were used in the study. Unconstrained and nondestructive pure moments in axial torsion (AT), lateral bending (LB), and flexion-extension (FE) were applied to each specimen after applying transsacral rod and after additional augmentation methods, including bilateral screws, facet screws, and pedicle screw and rod system. Range of motion (ROM) was calculated for each surgical treatment. The disc space was measured with lateral plain radiographs of intact specimens and after transsacral rod insertion to evaluate the amount of distraction. RESULTS: The mean ROM of the intact specimens was 3.5, 6.4, and 11.0 degrees in AT, LB, and FE, respectively. Standalone transsacral rod reduced ROM more than 40% compared with the intact condition (P=0.002). Bilateral screws further reduced the ROM in AT (64%) and LB (70%), but not in FE (53%). Both facet screws and pedicle screw and rod system achieved high construct stability under all loading conditions. The transsacral rod augmented with facet screws reduced ROM by 70%, 80%, and 90% compared with the intact condition. When augmented with pedicle screw and rod system, the transsacral rod reduced ROM by 73%, 87%, and 88% in AT, LB, and FE, respectively. There was no statistical difference between these 2 facet screws and pedicle screw and rod system (P>0.8). CONCLUSIONS: Transsacral rod fixation provides strong ligamentotaxis due to intact annulus. Standalone transsacral rod is able to reduce ROM significantly and achieve indirect decompression by distracting L5-S1 disc space. However, additional posterior fixation, such as facet screws or pedicle screws, is required to achieve better construct stability for successful fusion.     

Anatomy of the pectoralis minor tendon and its use in acromioclavicular joint reconstruction

Many procedures described for operative management of acromioclavicular joint separations entail transfer of the coracoacromial ligament. We sought to describe the anatomy and morphology of the pectoralis minor tendon better, to assess its anatomic potential as a substitute for sacrificing the coracoacromial ligament, and to compare the ultimate tensile strength of the pectoralis minor with that of the coracoacromial ligament and detached coracoclavicular ligament. The morphology of the pectoralis minor tendon was carefully delineated and compared with that of the coracoacromial ligament, and 10 paired fresh-frozen cadaveric shoulders were tested to failure by applying a single uniaxial tensile load. Anatomic study of the pectoralis minor tendon confirmed its adequacy as a source of local autograft tissue in acromioclavicular joint reconstruction. We hypothesize that, in cases of acromioclavicular joint separation necessitating operative intervention, the use of the pectoralis minor tendon as a potential source of autograft tissue is anatomically feasible and it is slightly stronger than the coracoacromial ligament.     

Frontiers in nephrology: early atherosclerosis--a view beyond the lumen

Endothelial dysfunction is an established clinical marker of early coronary artery disease and has been shown to be associated with increased cardiovascular morbidity and mortality. New concepts now extend the view of endothelial dysfunction beyond the traditional involvement of the coronary arterial endothelium alone. Recent research indicates that the coronary vessel wall, especially the vasa vasorum, as well as bone marrow-derived endothelial progenitor cells may be subject to proatherosclerotic changes, even before the development of angiographically evident endothelial dysfunction; therefore, "microvascular endothelial dysfunction," which is composed of dysfunction of the vasa vasorum's endothelium as well as "microcellular endothelial dysfunction," reflecting impaired mobilization and function of endothelial progenitor cells, may precede "macrovascular endothelial dysfunction." Vasa vasorum neovascularization, with endothelial leakage and dysfunction increasing influx of proinflammatory and proatherogenic cellular and noncellular substances into the vessel wall, is proposed as one feature of this new concept. In addition, the role of bone marrow-derived endothelial progenitor cells is discussed as are the potential impact of impaired progenitor cell mobilization, release from the marrow, and function in acute and stable coronary artery disease. Finally, potential future therapies are proposed, focusing on interventions that may prevent or diminish the development of the microvascular and microcellular endothelial dysfunction.     

Reduction in acute rejections decreases chronic rejection graft failure in children: a report of the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS).

Chronic rejection accounted for 32% of all graft losses in 7123 pediatric transplants. In a previous study acute, multiple acute and late acute rejections were risk factors for the development of chronic rejection. We postulated that the recent decrease in acute rejections would translate into a lower risk for chronic rejection among patients with recent transplants. We reviewed our data on patients transplanted from 1995 to 2000, and using multivariate analysis and a proportional hazards model developed risk factors for patients whose grafts had failed due to chronic rejection. A late initial rejection increased the risk of chronic rejection graft failure 3.6-fold (p < 0.001), while a second rejection resulted in further increase of 4.2-fold (p < 0.001). Recipients who received less than 5 mg/kg of cyclosporine at 30 days post-transplant had a relative risk (RR) of 1.9 (p = 0.02). Patients transplanted from 1995 to 2000 had a significantly lower risk (RR = 0.54, p < 0.001) of graft failure from chronic rejection than those who received their transplants earlier (1987-94). Since we were able to demonstrate that there is a decreased risk of chronic rejection graft failure in our study cohort, we would conclude that the goal of future transplants should be to minimize acute rejections.     

Linear and angular measurements of computer-generated models: are they accurate, valid, and reliable?

INTRODUCTION: Traditional advanced imaging modalities such as CT and MRI are limited in their ability to perform accurate linear distance and angular measurements regardless of anatomical orientation. The construction of 3D models has been used to perform anthropometric analyses as well as in the reconstruction of rapid prototypes. We hypothesized that such measurements would be precise to within 2 mm or 2 degrees of measurements performed with a coordinate measurement machine (CMM). We also hypothesized that there would be a high degree of interobserver reliability with these measurements. MATERIALS AND METHODS: Multiple aluminum screws were implanted in various positions in three foam pelvises which were subsequently scanned by CT and rendered as 3D models using a commercially available software package (Mimics). Linear and angular measurements were performed using a CMM machine, the software package, and a dial caliper or goniometer. The deviation of the measurements from the CMM data was compared using ANOVA. The interobserver reliability of both the manual and computer-generated measurements was calculated. RESULTS: The mean difference between the CMM distances and those measured manually and with the software was 2.12 +/- 1.20 mm and 1.57 +/- 1.05 mm, respectively. The mean difference between the CMM angular measurements and the angular measurements performed manually and with the software was 4.07 +/- 4.70 degrees and 1.62 +/- 1.32 degrees, respectively. In all cases, the manual measurements were significantly less accurate (p < 0.0001) and there was a high degree of interobserver reliability. CONCLUSIONS: Computer-generated measurements taken from three-dimensionally reconstructed models are more accurate than manual measurements and are within 2 mm and 2 degrees of measurements performed with a CMM. These measurements have high interobserver reliability.     

Improved outcomes using a systematic and evidence-based approach to the laparoscopic Roux-en-Y gastric bypass in a single academic institution

No standardized approach exists for laparoscopic Roux-en-Y gastric bypass (LRYGB). At a newly instituted bariatric surgery program, four experienced laparoscopic surgeons used the systematic and evidence-based approach consisting of multidisciplinary preoperative evaluation, screening, and education; standardized operative technique; inpatient clinical pathway; and close postoperative follow-up. The outcomes were subsequently analyzed to determine if this approach improved the morbidity and mortality. From January 2003 to June 2006, 835 consecutive LRYGBs were performed. The patient population was 85 per cent women with a mean body mass index (BMI) of 50.4 kg/m2 (range 33-96 kg/m2). The mean age was 44 (range 15-67). Sixty-two per cent of the patients had previous abdominal or pelvic operations. The conversion rate to open surgery was 0.2 per cent. The average length of hospital stay was 2.6 days (range 2-13 days). There were no anastomotic leaks or deaths. The 30-day readmission and re-operation rates were 3.2 per cent and 1.8 per cent, respectively. The incidence of anastomotic stricture, marginal ulcer, bleeding, pulmonary embolism, and internal hernia was 0.8 per cent, 3.5 per cent, 4.2 per cent, 0.1 per cent, and 0.4 per cent, respectively. A systematic and evidence-based approach to the LRYGB by experienced laparoscopic surgeons resulted in a lower incidence of complications when compared with the published results from other comparable institutions.     

Use of pre-operative Tc99m-Sestamibi scintigraphy and intraoperative parathyroid hormone monitoring to eliminate neck exploration in mediastinal parathyroid adenocarcinoma

A 66-year-old white woman was found to have an elevated serum calcium and parathyroid hormone (PTH) on routine health evaluation. Physical examination was unremarkable as was ultrasonography of the neck. A sestamibi parathyroid scan revealed abnormal uptake in the anterior mediastinum. Computed tomography of the chest demonstrated an anterior mediastinal mass compatible with a parathyroid adenoma but no neck masses. The patient underwent mediastinoscopy that was converted to a median sternotomy to fully access the mass. The mass was completely resected with surrounding thymus gland. Frozen section confirmed that excised tissue was parathyroid gland in origin. An intraoperative PTH obtained 20 minutes after specimen removal showed a decrease of more than 50% from preoperative levels. The strategy for initial surgery for hyperparathyroidism when a sestamibi scan is "positive" in the mediastinum (only) is a point of some controversy. Traditional recommendations have been to "clear the neck" of abnormal parathyroid tissue before undertaking a more morbid sternotomy. Mediastinoscopy was attempted to remove the mediastinal lesion and to avoid a sternotomy. Preoperative Tc99m sestamibi scintigraphy, frozen section histology, and intraoperative PTH monitoring permitted the authors to conclude that neck exploration was unnecessary.     

Intramedullary strut substitution and impaction allografting cemented revision for the treatment of a periprosthetic fracture in a severely compromised femur

Revision for the treatment of a B3 periprosthetic femoral fracture often requires proximal femoral allograft arthroplasty in physiologically young or tumor prostheses in elderly patients. Extramedullary strut allograft augmentation can only be used when the host femur is structurally adequate for the insertion of the revision stem (periprosthetic femoral fractures type B2) and appears to be an attractive biological concept as early incorporation to the host bone results in a sound biomechanical construct. We report here the simultaneous use of whole femur intramedullary strut substitution along with an extramedullary strut graft placement, with impaction allografting revision to a long cemented femoral prosthesis, to augment the deficient metadiaphyseal bone stock (Paprosky type IV) for the treatment of a complex type B3 periprosthetic femoral fracture.