The Learning Curve for Robot-assisted Partial Nephrectomy: Impact of Surgical Experience on Perioperative Outcomes

Robot-assisted partial nephrectomy (RAPN) outcomes might be importantly affected by increasing surgical experience (EXP). The aim of the study is to investigate the effect of EXP on warm ischemia time (WIT), presence of at least one Clavien-Dindo ≥2 postoperative complication (CD ≥ 2), and positive surgical margins (PSMs) to define the learning curve for RAPN. We evaluated 457 consecutive patients diagnosed with a cT1-T2 renal mass were evaluated. EXP was defined as the total number of RAPNs performed by each surgeon before each patient's operation. Median WIT was 14 min and the rate of CD ≥ 2 and PSMs was 15% and 4%, respectively. At multivariable regression analyses adjusted for case mix, EXP resulted associated with shorter WIT (p < 0.0001) and higher probability of CD ≥ 2–free postoperative course (p = 0.001), but not with PSMs (p = 0.7). The relationship between EXP and WIT emerged as nonlinear, with a steep slope reduction within the first 100 cases and a plateau observed after 150 cases. Conversely, the relationship between EXP and CD ≥ 2–free course resulted linear, without reaching a plateau, even after 300 cases.Patient summary: Perioperative outcomes after robot-assisted partial nephrectomy (RAPN) are importantly and individually affected by surgeon's experience. After 150 RAPNs, no further improvement is observed with respect to ischemia time, but the learning curve appears endless with respect to complications.     

Expanded polytetrafluoroethylene-covered stent-grafts for transjugular intrahepatic portosystemic shunts in cirrhotic patients: Long-term patency and clinical outcome results

Purpose

To retrospectively analyse long-term patency and overall survival of cirrhotic patients treated with TIPSS using e-PTFE-covered stents. Additionally, prognostic factors for better patency and survival were analysed.

Materials and methods

Two hundred and eighty-five consecutive cirrhotic patients with severe portal hypertension-related symptoms were included. Follow-up, including clinical assessment and duplex ultrasound, was analysed up to end of study, patient’s death, liver transplantation or TIPSS-reduction. Patency rates and overall survival were estimated by the Kaplan-Meier method; potential differences in outcome between subgroups were calculated using the Pepe and Mori test.

Results

The 1-, 2- and 5-year primary patencies were 91.5 %, 89.2 % and 86.2 %, respectively, with no new shunt dysfunctions after 5 years’ follow-up. TIPSS revision was performed more often in ascites patients (P?=?0.02). The 1-, 4- and 10-year survival rates were 69.2 %, 52.1 % and 30.7 %, respectively. Survival was higher in Child-Pugh class A-B (P?=?0.04), in the recurrent bleeding group (P?=?0.008) and in patients with underlying alcoholic cirrhosis (P?=?0.01).

Conclusion

Long term, primary patency of e-PTFE-covered TIPSS stents remains very high (>80 %); shunt revision was required more frequently in ascites patients. Overall survival was better in Child-Pugh A-B patients with recurrent variceal bleeding and alcoholic liver cirrhosis.

Keypoints

? Long-term primary patency rate of e-PTFE-covered TIPSS stents remains very high. ? No new shunt dysfunction was found after 5 years of follow-up. ? Shunt revision was required more frequently in ascites patients. ? Four and 10 years’ overall survival was 50 and 30 %, respectively.

     

The geometrical precision of virtual bone models derived from clinical computed tomography data for forensic anthropology

Almost all European countries lack contemporary skeletal collections for the development and validation of forensic anthropological methods. Furthermore, legal, ethical and practical considerations hinder the development of skeletal collections. A virtual skeletal database derived from clinical computed tomography (CT) scans provides a potential solution. However, clinical CT scans are typically generated with varying settings. This study investigates the effects of image segmentation and varying imaging conditions on the precision of virtual modelled pelves. An adult human cadaver was scanned using varying imaging conditions, such as scanner type and standard patient scanning protocol, slice thickness and exposure level. The pelvis was segmented from the various CT images resulting in virtually modelled pelves. The precision of the virtual modelling was determined per polygon mesh point. The fraction of mesh points resulting in point-to-point distance variations of 2 mm or less (95% confidence interval (CI)) was reported. Colour mapping was used to visualise modelling variability. At almost all (>97%) locations across the pelvis, the point-to-point distance variation is less than 2 mm (CI = 95%). In >91% of the locations, the point-to-point distance variation was less than 1 mm (CI = 95%). This indicates that the geometric variability of the virtual pelvis as a result of segmentation and imaging conditions rarely exceeds the generally accepted linear error of 2 mm. Colour mapping shows that areas with large variability are predominantly joint surfaces. Therefore, results indicate that segmented bone elements from patient-derived CT scans are a sufficiently precise source for creating a virtual skeletal database.

     

Is there an effect of prenatal breech position on locomotion at 2.5 years?

The long-term effects of intra-uterine breech position on postnatal development of motor functions have not been systematically investigated. The aim of the present study was to investigate the possible effect of prenatal breech position on locomotion. Two complementary studies were conducted. Firstly, a gait analysis was carried out. Secondly, in a functional task the children were challenged to cross a gap until their maximum attainable crossing distance was reached. The mean age of the twenty-one children who participated in this study was 32.1 months (SD=4). Children who had lain in prenatal breech position (n=10) had a walking pattern comparable to the control group (n=11). There were no differences in step length, step width, foot rotation, foot rotation asymmetry, hip flexion, hip extension and range of motion of the hip. Thus, prenatal breech position, although a long-term effect was found, does not seem to have functional consequences on locomotion. However, the total amount of extra hip motion during the gap crossing was significantly smaller in children who had lain in breech position compared to the control group. This was due to significant less extra hip flexion at the side of the leading leg. Nevertheless, comparable maximum gaps were crossed in both groups. Apparently, these children had a different solution of the challenging task of gap crossing. They compensated the lack of extra hip flexion by applying more extra hip extension.     

Fraudulent use of digital radiography: methods to detect and protect digital radiographs

Digital radiography has become an indispensable diagnostic tool in dentistry today. To improve vision and diagnosis, dental x-ray software allows image enhancement (eg, adjusting color, density, sharpness, brightness, or contrast). Exporting digital radiographs to a file format compatible with commercial graphic software increases chances that information can be altered, added, or removed in an unethical manner. Dental radiographs are easily duplicated, stored, or distributed in digital format. It is difficult to guarantee the authenticity of digital images, which is especially important in insurance or juridic cases. Image-enhancement features applied to digital radiographs allow mishandling or potential abuse. This has been illustrated by several recently published studies. A standard authentication procedure for digital radiographs is needed. A number of manipulated radiographic images are presented to show concerns about security, reliability, and the potential for fraud. Antitampering techniques and methods of detecting manipulations in digital medical images are discussed.     

A high-dimensional joint model for longitudinal outcomes of different nature

In repeated dose-toxicity studies, many outcomes are repeatedly measured on the same animal to study the toxicity of a compound of interest. This is only one example in which one is confronted with the analysis of many outcomes, possibly of a different type. Probably the most common situation is that of an amalgamation of continuous and categorical outcomes. A possible approach towards the joint analysis of two longitudinal outcomes of a different nature is the use of random-effects models (Models for Discrete Longitudinal Data. Springer Series in Statistics. Springer: New York, 2005). Although a random-effects model can easily be extended to jointly model many outcomes of a different nature, computational problems arise as the number of outcomes increases. To avoid maximization of the full likelihood expression, Fieuws and Verbeke (Biometrics 2006; 62:424-431) proposed a pairwise modeling strategy in which all possible pairs are modeled separately, using a mixed model, yielding several different estimates for the same parameters. These latter estimates are then combined into a single set of estimates. Also inference, based on pseudo-likelihood principles, is indirectly derived from the separate analyses. In this paper, we extend the approach of Fieuws and Verbeke (Biometrics 2006; 62:424-431) in two ways: the method is applied to different types of outcomes and the full pseudo-likelihood expression is maximized at once, leading directly to unique estimates as well as direct application of pseudo-likelihood inference. This is very appealing when interested in hypothesis testing. The method is applied to data from a repeated dose-toxicity study designed for the evaluation of the neurofunctional effects of a psychotrophic drug. The relative merits of both methods are discussed. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Sports and recreation activity of ankle arthritis patients before and after total ankle replacement

BACKGROUND: Total ankle replacement is a possible treatment for ankle arthritis; however, participation in sports after this procedure has not yet been analyzed. HYPOTHESES: There is a significant increase of sports activity after total ankle replacement in patients with arthritis. There is a significant correlation between sports activity and American Orthopaedic Foot and Ankle Society hindfoot score in patients after total ankle replacement. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A clinical evaluation was performed preoperatively and at follow-up after total ankle replacement in 147 patients (152 ankles) with ankle arthritis (mean age, 59.6 years; range, 28-86 years). Ankle arthritis origin, patient satisfaction, range of motion, American Orthopaedic Foot and Ankle Society hindfoot score, radiologic assessment, and rate, level, and type of sports activity were documented at both evaluations. The mean follow-up was 2.8 years (range, 2-4 years). RESULTS: Preoperative diagnosis was posttraumatic osteoarthritis in 115 cases (76%). At total ankle replacement follow-up, excellent and good outcomes were reported in 126 cases (83%); 105 cases (69%) were pain free. The mean range of motion pre-operatively was 21 degrees (range, 0 degrees -45 degrees ); after total ankle replacement, it was 35 degrees (range, 10 degrees -55 degrees ; P < .05). The preoperative American Orthopaedic Foot and Ankle Society score was 36 points; after total ankle replacement, it was 84 points (P < .001). Before surgery, 36% of the patients were active in sports; after surgery, this percentage rose to 56% (P < .001). After total ankle replacement, sports-active patients showed a significantly higher hindfoot score than did patients not active in sports: 88 versus 79 points (P < .001). The 3 most frequent sports activities were hiking, biking, and swimming. CONCLUSION: There was a significant increase of sports activity by treating ankle arthritis patients with total ankle replacement. Sports-active total ankle replacement patients showed better functional results than did inactive ones.