Pullout strength of anterior spinal instrumentation: a product comparison of seven screws in calf vertebral bodies

A lot of new implant devices for spine surgery are coming onto the market, in which vertebral screws play a fundamental role. The new screws developed for surgery of spine deformities have to be compared to established systems. A biomechanical in vitro study was designed to assess the bone–screw interface fixation strength of seven different screws used for correction of scoliosis in spine surgery. The objectives of the current study were twofold: (1) to evaluate the initial strength at the bone–screw interface of newly developed vertebral screws (Universal Spine System II) compared to established systems (product comparison) and (2) to evaluate the influence of screw design, screw diameter, screw length and bone mineral density on pullout strength. Fifty-six calf vertebral bodies were instrumented with seven different screws (USS II anterior 8.0 mm, USS II posterior 6.2 mm, KASS 6.25 mm, USS II anterior 6.2 mm, USS II posterior 5.2 mm, USS 6.0 mm, USS 5.0 mm). Bone mineral density (BMD) was determined by quantitative computed tomography (QCT). Failure in axial pullout was tested using a displacement-controlled universal test machine. USS II anterior 8.0 mm showed higher pullout strength than all other screws. The difference constituted a tendency (P = 0.108) when compared to USS II posterior 6.2 mm (+19%) and was significant in comparison to the other screws (+30 to +55%, P < 0.002). USS II posterior 6.2 mm showed significantly higher pullout strength than USS 5.0 mm (+30%, P = 0.014). The other screws did not differ significantly in pullout strength. Pullout strength correlated significantly with BMD (P = 0.0015) and vertebral body width/screw length (P < 0.001). The newly developed screws for spine surgery (USS II) show higher pullout strength when compared to established systems. Screw design had no significant influence on pullout force in vertebral body screws, but outer diameter of the screw, screw length and BMD are good predictors of pullout resistance.     

Ex vivo Search for Sentinel Node in Postmastectomy Specimens: Should We Use a Transverse Incision for Mastectomy?

Background According to the concept of sentinel node (SN), the lymphatic pathway leading to SN should be regarded as the main and the most important lymphatic route from primary tumor to regional lymph nodes. We performed ex vivo blue-dye SN mapping in postmastectomy specimens to assess whether the main lymphatic tract leading to SN is completely removed during mastectomy. We assumed that ex vivo identification of SN may be possible only if the entire lymphatic tract leading to sentinel node is removed from within the postmastectomy specimen. Methods Blue dye (1 mL) was injected intracutaenously, periareolary into each of 28 postmastectomy specimens. In 13 cases mastectomy was performed with the use of transverse skin incision; in 15 cases oblique incision was used. Results The use of transverse skin incision during modified radical mastectomy allowed identification of the sentinel node and removal of the entire lymphatic pathway leading to sentinel node only in 4 of 15 cases (31%). Conversely, the use of oblique skin incision during modified radical mastectomy allowed identification of the sentinel node and removal of the entire lymphatic pathway leading to sentinel node in 12 of 15 cases (80%). Conclusions Our experiment revealed that the use of transverse skin incision during modified radical mastectomy may not be the best choice for breast cancer patients. In our opinion, this observation may be especially important for patients not irradiated postoperatively.     

Percutaneous transtracheal emergency ventilation with a self-made device in an animal model

BACKGROUND: Special equipment for emergency percutaneous transtracheal ventilation is often not immediately available. We used a self-made device consisting of a three-way stopcock connected between a G-15 transtracheal airway catheter and an oxygen supply in a simulated 'cannot intubate, cannot ventilate' scenario and tested the hypothesis that the effectiveness of the device depends on the body weight of the experimental animals. METHODS: With approval of the local animal protection committee, two groups of six pigs each with a body weight of 21 +/- 2 and 36 +/- 6 kg, respectively, were tracheally intubated and mechanically ventilated after induction of anesthesia. Hemodynamic monitoring included cardiac output and arterial, central venous and pulmonary artery pressures. An emergency transtracheal airway catheter was inserted into the trachea and a situation of partial expiratory airway obstruction was created. Each animal was ventilated for 15 min via the transtracheal airway catheter with the self-made device (FiO(2) 1.0 at an oxygen flow of 15 l x min(-1); respiratory rate of 60 min(-1); I/E ratio approximately 1:1). RESULTS: Whereas satisfactory oxygenation was achieved in all animals, sufficient ventilation was obtained only in the lightweight animals. CONCLUSIONS: Adequate oxygenation could be provided by jet-like transtracheal ventilation with a simple self-made device using easily available materials. Sufficient ventilation depends on the body weight of the animals.     

Initial prevalence of anal human papilloma virus infection in liver transplant recipients

Although liver transplant recipients are at increased risk of human papilloma virus (HPV)‐related anal cancer, limited data are available regarding the initial prevalence of anal HPV infection in this population. Anal swabs collected from 50 liver transplant recipients within the first three postoperative weeks were subjected to real‐time polymerase chain reaction for detection of the four HPV genotypes: 6, 11, 16, and 18. Predictors of any, low‐risk, and high‐risk anal HPV infection were evaluated. Overall, the prevalence of any anal HPV infection was 18.0%, with the corresponding rates for high‐ and low‐risk HPV genotypes being 8.0% and 10.0%, respectively. Infection with any type of anal HPV was higher in patients with hepatitis B virus (HBV) infection (P = 0.027), ≥3 sexual partners (P = 0.031), and alcoholic liver disease (P = 0.063). HBV infection was the only factor significantly associated with high‐risk HPV infection (P = 0.038). Male sex (P = 0.050), age ≥52 years (P = 0.016), ≥30 sexual partners (P = 0.003), age at first intercourse ≤18 years (P = 0.045), and time since first intercourse ≥38 years (P = 0.012) were identified as predictors of low‐risk HPV infection. These results indicate that HPV vaccination of liver transplant candidates and screening for anal HPV infection in high‐risk groups should be considered.     

Management of a young patient with dextrocardia,atrial septal defect,and Eisenmenger syndrome with venous‐venous extracorporeal membrane oxygenation and heart‐lung transplantation

Dextrocardia is a rare congenital condition which presents important challenges for surgical management. We discuss a patient with dextrocardia, atrial septal defect, and Eisenmenger syndrome, which ultimately led to decompensated end‐stage lung disease and heart‐lung transplant. Venous‐venous extracorporeal membrane oxygenation was an important strategy to bridge the patient until donor organs became available. Transplantation of a heart‐lung block allowed for the treatment of the patient's underlying congenital heart defect, anatomic reversal of dextrocardia with appropriate venous and arterial connections, and management of pulmonary damage from pulmonary hypertension.     

Mucosal loss with increased expression of IL-6, IL-8, and COX-2 in a formula-feeding only neonatal rat model of necrotizing enterocolitis

Introduction

The aim of our study is to establish a reliable neonatal rat model by formula feeding only for evaluation of early surgical intervention on the course of experimental necrotizing enterocolitis (NEC).

Material and methods

Newborn Sprague–Dawley rats were divided into 50 breast-fed (group 1) and 38 formula fed (Similac/Esbilac, group 2) animals. The pups were sacrificed on the 4th, 5th, and 6th day of life and the terminal intestine examined for macroscopic and histologic changes as well as cytokine expression.

Results

The histological mucosal damage was significantly higher of group 2 compared to group 1. The area of the vital mucosa of group 2 was significantly (58.57%, p < 0.001) lower compared to group 1 (75.12%). The mRNA expression of the inflammatory cytokines IL-6, IL-8 and COX-2 was significantly 2-, 5- and 10-fold increased in group 2 compared to group 1.

Discussion

Formula fed newborn rats displayed an inflammatory enterocolitis similar to human NEC. Our study demonstrates a significant loss of mucosa in animals with NEC having increased expression levels of IL-6, IL-8 and COX-2. Mucosal loss appears to be a distinct feature of experimental NEC and has to be correlated with the human disease.     

Salvage radiotherapy in patients with persistently detectable PSA or PSA rising from an undetectable range after radical prostatectomy gives comparable results

Purpose

Salvage radiotherapy (SRT) is applied routinely in patients with a biochemical relapse after radical prostatectomy (RP). Although the detection threshold for relapse after RP has steadily been lowered, only about 30 % of the SRT patients achieve a durable response. We have previously shown the association between a PSA decrease below detectable levels after SRT and biochemical progression-free survival (BPFS). After recalculating our data according to a more recent definition of biochemical failure after SRT, we now show the significance of the post-RP PSA nadir.

Materials and methods

Among 159 prostate cancer patients without hormonal treatment after RP, SRT was given to 72 patients with persistently detectable PSA after RP and to 87 whose PSA increased out of an undetectable range. The median pre-SRT PSA was 0.29 ng/ml for the former group and 0.34 ng/ml for the latter group. A radiation dose of 66.6 Gy was applied to the prostate bed.

Results

The overall median follow-up time was 41.7 months. The probability for BPFS after this period was 52.8 % in 72 patients with persistently detectable PSA after RP and 65.4 % in 87 patients who had a post-RP PSA nadir below detection limit. Univariate and multivariate analyses showed no significant difference in BPFS of both patient groups (p > 0.05).

Conclusion

Our findings suggest that SRT is a viable treatment option for patients with persistently detectable PSA, giving similar results as in patients whose PSA increases out of an undetectable range after RP.     

Endovascular versus open approach to aortic aneurysm repair surgery: rates of postoperative delirium

Purpose

Our objective was to compare open and endovascular aortic aneurysm repair with respect to postoperative delirium.

Methods

After Institutional Ethics Review Board approval, we conducted a retrospective review of all patients who underwent abdominal and thoraco-abdominal aortic aneurysm repair surgery at Toronto General Hospital during June 2006 to December 2007. Patients were classed into either the OPEN or the endovascular (EVAR) group based on the type of surgery and were assessed for the presence of delirium after surgery. The NEECHAM Confusion Scale and the validated chart review instrument were used for diagnosis of delirium. Patients with dementia and/or abnormal levels of consciousness preoperatively were excluded.

Results

There were 256 patients included in the study, 149 (58%) in the OPEN group and 107 (42%) in the EVAR group. Patients in the EVAR group were considerably older, 74 (10) yr vs 68 (9) yr, and they had shorter duration of surgery, 150 [119, 180] min vs 200 [165, 260] min, respectively, P?<?0.0001. Postoperative delirium was present in 43 (29%) patients in the OPEN group and 14 (13%) patients in the EVAR group (95% confidence interval [CI], 22 to 36 vs 95% CI, 7 to 19, respectively; P?=?0.003). Hospital length of stay was 8.3 [6.6, 13.4] days in the OPEN group and 4.5 [3.1, 6.4] days in the EVAR group, P?<?0.0001.

Conclusions

Perioperative management of patients undergoing endovascular aortic aneurysm repair was associated with lower rates of delirium after surgery than that of patients undergoing open aortic aneurysm repair.