Revisiting sample size: are big trials the answer?

The superiority of the evidence generated in randomized controlled trials over observational data is not only conditional to randomization. Randomized controlled trials require proper design and implementation to provide a reliable effect estimate. Adequate random sequence generation, allocation implementation, analyses based on the intention-to-treat principle, and sufficient power are crucial to the quality of a randomized controlled trial. Power, or the probability of the trial to detect a difference when a real difference between treatments exists, strongly depends on sample size. The quality of orthopaedic randomized controlled trials is frequently threatened by a limited sample size. This paper reviews basic concepts and pitfalls in sample-size estimation and focuses on the importance of large trials in the generation of valid evidence.     

Postoperative delirium and postoperative cognitive dysfunction in the elderly - what are the differences?

Postoperative cognitive impairment is an increasingly common problem as more elderly patients undergo major surgery. Cognitive deficits in the postoperative period cause severe problems and are associated with a marked increase in morbidity and mortality. There are two main entities of postoperative cognitive decline, delirium and postoperative cognitive dysfunction, which are often reported as being part of the same continuum. Although there are similarities in the predisposing factors, it seems unlikely that they share the same pathophysiology. Both have multifactorial pathogenesis but differ in numerous other ways, with delirium being well-defined and acute in onset and postoperative cognitive dysfunction (POCD) being subtler and with longer duration. This review aims to provide an overview of the differences in the diagnosis of the two entities and to illustrate the methodological problems that can be encountered when evaluating cognitive deficits postoperatively.     

Laparotomy closure and incisional hernia prevention - what are the surgical requirements?

In the light of an incisional hernia incidence of between 10 and 20 % that remains constantly high in spite of modifications of suture materials and suture techniques, intensified scientific efforts aiming at incisional hernia prevention are -required. This article reviews the scientific results dealing with incisional hernia incidence, time of manifestation, risk factors and the influence of suture material and suture technique. A lack of evidence-based data and no current consensus concerning the ideal material and technique to close laparotomies has to be mentioned. To encourage a novel approach to incisional hernia -prevention, the results of experimental studies which demonstrate the negative effects of conventional laparotomy closure on the abdominal wall are discussed. Histology and additionally -laser-fluorescence angiography reveal the weak-en-ing of abdominal wall structures and abdominal wall perfusion after directly suturing the -incisional edges. Additionally, inadequate suture -tension has an influence on collagen quantity and quality in the healing incision. Further investigations with a suture simulator have made clear that surgical sutures vary widely in precision and reproducibility of suture tension when completed only under visual and tactile control. As suture tension dynamics cannot be measured due to the lack of adequate devices, an implantable sensor has been developed that reveals a loss of suture tension of up to 60 % of the initial tension in the first 2 hours after completion of laparotomy closure. These results have led to the development and experimental use of a bridging closure with a tension-banding technique. This technique has almost no influence on abdominal wall per-fusion, leaves the architecture and dynamics of the abdominal wall intact, and results in a favour-able ultra-structural composition of collagen and a mechanically stable laparotomy healing after 15 months. Measures to prevent incisional hernia formation - which is in fact the post-operative complication in surgery most frequently leading to re-operation - require intensified research activities. Success will only be achieved if the development of -unconventional closure techniques is encouraged and the beaten path of suturing the incisional edges is discarded.     

Radiation exposure and the urologist: what are the risks?

Purpose

Endourology is established in urology practice with routine use of fluoroscopic guidance. Medical personnel are rarely exposed to direct radiation exposure but secondary exposure occurs via radiation scatter. There are few reports on scatter radiation exposure and the subsequent risk to medical personnel involved in urological fluoroscopic procedures. We review the risks of scatter radiation exposure to medical personnel with reference to the routine use of fluoroscopic imaging in urological practice.

Materials and Methods

We measured staff radiation exposure during a series of ureteral endourological procedures using LiF:Mg,Ti thermoluminescent dosimeters placed at the extremities of the operating surgeon, the assistant and the scrub nurse. Doses for percutaneous nephrolithotomy (PCNL) procedures were calculated by extrapolating from the ureteral procedure thermoluminescent dosimeter data. Theoretical scattered radiation dose rates were also calculated.

Results

The average ureteral procedure fluoroscopy time was 78 seconds with an exposure rate of 71 kV, 2.4 mA. The surgeon received the highest radiation exposure with the lower leg (11.6 ± 2.7 μGy) and foot (6.4 ± 1.8 μGy) receiving more radiation than the eyes (1.9 ± 0.5 μGy) and hands (2.7 ± 0.7 μGy). For a predicted annual caseload of 50 ureteral cases, the dose received does not exceed 0.12% of the Ionising Radiations Regulations 1999 annual dose limit for adult workers. Radiation exposure during PCNLs is higher but does not exceed 2% of the annual dose limits even if 50 PCNLs are performed annually.

Conclusions

Fluoroscopic screening results in radiation exposure of medical personnel. The estimate of maximum scatter radiation exposure to the surgeon for 50 PCNL procedures a year did not exceed 10 mGy. This amount is less than 2% of permissible annual limits of equivalent dose to the extremities. Medical personnel should be aware of scatter radiation risks and minimize radiation exposure when involved in fluoroscopic screening procedures.     

What are the cardiovascular complications of the analgesics and glucocorticoids?

When prescribing a non-steroidal anti-inflammatory treatment but also an analgesic or a glucocorticoid, the cardiovascular risk of the patient should be assessed. The analgesics have few cardiovascular side effects and the main complications observed are linked essentially to the vagal action of the opioids. Acetaminophen is considered by several scientific societies to be the first line analgesic treatment, particularly in case of cardiovascular risk but with caution since cardiovascular toxicity of acetaminophen cannot be totally excluded. An overdose of dextropropoxyphene can result in cardiotoxicity. On the other hand, the glucocorticoids need to be prescribed cautiously, at the lowest possible dose and for the shortest possible duration due to the non-negligible cardiovascular risk, hypertension, dyslipidemia, hypokaliemia.     

Management of focal cartilage defects in the knee - Is ACI the answer?

Injuries to the articular cartilage of the knee are common. They alter the normal distribution of weightbearing forces and predispose patients to the development of degenerative joint disease. The management of focal chondral lesions continues to be problematic for the treating orthopaedic surgeon. Although many treatment options are currently available, none fulfill the criteria for an ideal repair solution: a hyaline repair tissue that completely fills the defect and integrates well with the surrounding normal cartilage. Autologous chondrocyte implantation (ACI) is a relatively new cell-based treatment method for full-thickness cartilage injuries that in recent years has increased in popularity, with early studies showing promising results. The current article reviews the nature of cartilage lesions in the knee and the treatment modalities utilized in their management, focusing on the role ACI plays in the surgical treatment of these complex injuries.     

Who are the surgery clerkship directors and what are their educational needs?

BACKGROUND: The surgery clerkship director is a key individual in the surgery department's educational mission and yet there has been no prior effort to describe this group or identify their learning needs. The purpose of this study was to develop a demographic profile and an educational needs assessment for surgery clerkship directors. METHODS: A survey instrument was designed based on existing literature and distributed to surgery clerkship directors in the United States and Canada. RESULTS: Surveys were returned from 108 subjects (77%). The majority of clerkship directors strongly agree that directing is a positive experience but express concern that the job demands may impede their professional careers. The perceived educational needs identified related primarily to the development and management of the student education curriculum. CONCLUSIONS: Surgery clerkship directors are experienced academic surgeons who report high levels of satisfaction. They identify a number of important educational needs of the position and express concern about the requirements of the position on their academic careers.