John A. Cartmill

Long-term analysis of the use of transanal rectal advancement flaps for complicated anorectal/vaginal fistulas

Transanal rectal advancement flap (TRAF) is a surgical option in the management of rectovaginal and other complicated fistulas involving the anorectum. Most reported series have a short follow-up. PURPOSE: This study was undertaken to determine the long-term success, safely, applicability, and factors affecting recurrence in patients managed with TRAF, including patients with Crohns disease. METHODS/MATERIALS: Retrospective analysis of all patients undergoing endorectal advancement flaps at a single institution between 1988 and 1993 was performed. One hundred one patients were identified (70 percent female; 30 percent male). Included were 52 patients with rectovaginal, 46 with anal perineal, and 3 with rectourethral fistulas. Causes were obstetric injury in 13 patients, Crohns disease in 47, cryptoglandular in 19, mucosal ulcerative colitis in 7, and surgical trauma or undefined causes in 15 patients. RESULTS: No mortality occurred. Median follow-up was 31 (range, 1–79 months). Immediate failure (within one week of the repair) was seen in 6 percent of patients. Statistically (tP<0.001) higher recurrence rates were observed in patients who had undergone previous repairs. Mean hospital stay was four days. Overall recurrence was seen in 29 patients (29 percent). Seventy-five percent of all recurrences occurred within the first 15 months; however, recurrence was noted for up to 55 months after repair. Etiology of fistula, use of constipating medications, antibiotic use, and most importantly associated Crohns disease did not statistically affect recurrence rates. Failure rate was only influenced by previous number of repairs. CONCLUSION: TRAF is a safe technique for managing complicated anorectal and rectovaginal fistulas, including patients with Crohns disease. Long-term follow-up is essential to accurately report recurrence rates.

Virtual reality simulators: Current status in acquisition and assessment of surgical skills

Medical technology is currently evolving so rapidly that its impact cannot be analysed. Robotics and telesurgery loom on the horizon, and the technology used to drive these advances has serendipitous side‐effects for the education and training arena. The graphical and haptic interfaces used to provide remote feedback to the operator – by passing control to a computer – may be used to generate simulations of the operative environment that are useful for training candidates in surgical procedures. One additional advantage is that the metrics calculated inherently in the controlling software in order to run the simulation may be used to provide performance feedback to individual trainees and mentors. New interfaces will be required to undergo evaluation of the simulation fidelity before being deemed acceptable. The potential benefits fall into one of two general categories: those benefits related to skill acquisition, and those related to skill assessment. The educational value of the simulation will require assessment, and comparison to currently available methods of training in any given procedure. It is also necessary to determine – by repeated trials – whether a given simulation actually measures the performance parameters it purports to measure. This trains the spotlight on what constitutes good surgical skill, and how it is to be objectively measured. Early results suggest that virtual reality simulators have an important role to play in this aspect of surgical training.

Defecation proctography and translabial ultrasound in the investigation of defecatory disorders.

Defecation proctography is the standard method used in the investigation of obstructed defecation. Translabial ultrasound has recently been shown to demonstrate rectocele, enterocele and rectal intussusception. We performed a comparative clinical study to determine agreement between the two methods.

Resistance forces acting on suture needles

Understanding the resistance forces encountered by a suture needle during tissue penetration is important for the development of robotic surgical devices and virtual reality surgical simulators. Tensile forces applied to skin and tendon during suturing were measured. Fresh sheep achilles tendons were tensioned with a static load 4.9 N, 9.8 N or 19.6 N and sheepskin with 0.98 N, 2.9 N or 4.9 N static load. A straight 2/0 cutting suture needle in series with a load cell on a materials testing machine penetrated the tissue at 90 degrees with a velocity of 1, 5 or 10mm/s for each tissue tension (n=5). Continuous load versus displacement data was obtained and penetration load and stiffness were noted. The load versus displacement curve for skin during needle penetration demonstrated two characteristic peaks, corresponding to initial penetration and emergence of needle from the undersurface of the tissue. Increasing the tension within the tissue (skin and tendon) increased the amount of force required to penetrate the tissue with a suture needle (p<0.05). Needle displacement rate did not affect the resistance to needle penetration (p<0.05). This study provides a simple model for measuring force-feedback during needle penetration of soft tissues and is a good starting point for future studies of the penetration resistance properties of human tissues.

Linguistic analysis of verbal and non-verbal communication in the operating room

Surgery can be a triumph of co‐operation, the procedure evolving as a result of joint action between multiple participants. The communication that mediates the joint action of surgery is conveyed by verbal but particularly by non‐verbal signals. Competing priorities superimposed by surgical learning must also be negotiated within this context and this paper draws on techniques of systemic functional linguistics to observe and analyse the flow of information during such a phase of surgery.

A compliant tip reduces the peak pressure of laparoscopic graspers

Background:  Previous studies have demonstrated that high pressures are generated at the tips of laparoscopic graspers, which can cause tissue injury. This study examines the effect of a compliant edge on tip pressure.

A curved edge moderates high pressure generated by a laparoscopic grasper.

Background: Very high pressures are generated at the interface between the tip of laparoscopic graspers and tissue. The pressure profile suggests that the high pressure is due to stress concentration at the edge of the jaw. Stress concentration at an edge can be modified by curving the edge. This study sought to determine the effect of a curved edge on pressures generated by the jaw of a laparoscopic grasper. Methods: Pressure generated at the instrument tissue interface was measured by a thin film pressure transducer. The two instruments that we compared were identical in every respect except the profile of the jaw edge. One was unmodified; the other had a rounded grasping edge. Load and handle pressure were constant throughout. Tissue pressures generated by the grasper were recorded as the angle of load was increased from vertical (0°) to 135°. Results: Localized pressures at the tip of the unmodified instrument reached a maximum of 1500 kPa. Pressures at the tip of the curved instrument reached a maximum of 920 kPa under identical conditions. Conclusion: High pressures generated at the tip of laparoscopic graspers can be reduced by rounding the edge of the jaw.

Extraction of myosin light chains and actin from bovine cardiac muscle acetone powder

A joint preparation of the two myosin light chains and actin from bovine cardiac muscle acetone powder is described. There is a significant improvement in the ease of purification, while the yield of the myosin light chains equals the best yields obtained from the use of established techniques. The actin yield greatly exceeds that obtained in an earlier published report.

Imaging in patients with obstructed defecation

Piloni et al. make an important contribution with ‘‘MRdefecography in obstructed defecation syndrome (ODS): technique, diagnostic criteria, and grading’’ [1]. It is pleasing to see an increasing trend toward comprehensive assessment of patients suffering from ODS in the gray zone between gynecology, urogynecology, gastroenterology, and colorectal surgery inhabited by women experiencing the effects of rectocele, enterocele, rectal intussusception, and anismus. Consensus can only be built on scientific fact, but such fact has first to be uncovered. At the moment, we are still enveloped in ignorance when it comes to the etiology, pathogenesis, and interactions of the conditions that underlie ODS and it is not surprising that there is so little agreement regarding treatment. Piloni et al. make a bold step toward an all-encompassing classification based on images of disorders of functional anatomy associated with ODS. However, the true value of the paper lies in the detailed descriptions of the patterns of altered anatomy and the ability of magnetic resonance imaging (MRI) to demonstrate them. Classification and categorization may have to wait, eventually to be informed by a more solid understanding of etiology and pathophysiology, but the authors are to be congratulated for their efforts and for making such a compelling case for the inclusion of the imaging specialist (rather than the image alone) in the multidisciplinary approach to this disorder. The use of MRI is restricted by availability and cost and it must be acknowledged that MRI is not as dynamic as translabial or transperineal ultrasound imaging which has been developing in this field over the last 20 years. Indeed, 4D translabial imaging allows multiplanar or tomographic real-time imaging in any freely definable plane, has excellent tissue discrimination, and also visualizes the modern mesh implants that are virtually invisible to radiological techniques including MRI [2]. The dynamic nature of ultrasound (allowing acquisition speeds of 30 Hz and more in a single plane and 4–8 Hz in volumes encompassing the entire pelvic floor) continues to inform the understanding of functional anatomy and tissue biomechanical properties and is an alternative to defecography [3, 4]. Ultrasound has provided a wealth of insight into the role of the levator ani for pelvic organ support and anorectal function. We now know that the levator ani is commonly damaged in childbirth [5, 6], that the use of forceps is the main risk factor [7], and that such tears and overdistension lead to excessive distensibility of the levator hiatus, the largest potential site for herniation in the human body [8]. This damage is associated with symptoms and signs of female pelvic organ prolapse [8, 9], with rectal intussusception [10] and with prolapse recurrence after pelvic reconstructive surgery [11–13]. It is no surprise that a radiologist is likely to prefer MRI and a clinician the convenience and instant availability of an ultrasound machine: each has its strengths and weaknesses. It is likely that each imaging modality may complement the other, with the MRI’s ‘‘reach’’ and the ultrasound’s sense of compliance and movement complementing one another. MRI is not as good as ultrasound for demonstrating ‘‘ballooning,’’ for example, and ultrasound cannot show the pudendal nerves. One paradoxical ‘‘disadvantage’’ of ultrasound is that it may be too inexpensive and too simple. The formality, expense, and inconvenience of an MRI lend the technique a gravitas that may be out of proportion to its value in this syndrome at the moment. H. P. Dietz (&) J. Cartmill University of Sydney, Penrith, NSW, Australia e-mail: hpdietz@bigpond.com

SE10 SURGICAL TEAMWORK: SYSTEMIC FUNCTIONAL LINGUISTICS AND THE ANALYSIS OF VERBAL AND NON VERBAL MEANING IN SURGERY

Purpose  Surgeons rely on teamwork, yet beyond an appreciation that some teams are more enjoyable to work in than others, or more effective, there is little understanding of the myriad complex interactions that make teamwork possible.