Injuries of the carpus and scaphoid

The scaphoid is one of eight carpal bones which lie in two rows (Figure 1). They are articulated together to form a semicircle, the convexity of which is proximal and articulates with the forearm bones. The scaphoid occupies the most radial position (thumb side) in the proximal row. It is a boat-shaped bone, which articulates directly with the radius proximally and is a critical link in the mechanism of the carpus. The scaphoid is commonly divided into four distinct parts: the proximal pole, the waist, the distal body and the tuberosity. It is a key bone to both wrist motion and stability.

Robot-assisted minimally invasive lung brachytherapy

BACKGROUND

This paper presents a novel alternative for the treatment of lung cancer. The method consists of accessing the lung through small incisions in a minimally invasive manner in order to insert radioactive seeds directly into the lung using a robotic surgical system.

METHODS

An experimental test-bed to evaluate the feasibility of this approach has been developed. It consists of two surgical robotic systems, a device specifically designed to robotically implant radioactive seeds, needle tracking software, ultrasound imaging, electromagnetic tracking, and a surgical box that mimics a patient's thorax. A detailed comparison has been performed between currently available access options and robot-assisted minimally invasive access.

RESULTS

The results show insignificant differences in accuracy between the methods, with the exception of a significant improvement when electromagnetic (EM) guidance was added to the non-robotic techniques. The navigation system reduced the number of attempts for all seed delivery methods. Significant reductions in time were achieved in the minimally invasive procedures by the addition of EM guidance.

CONCLUSIONS

The performance achieved when using robotic systems and image guidance for minimally-invasive brachytherapy is clinically comparable to that achieved in an open surgery procedure, while reducing the invasiveness of the procedure, improving ergonomic conditions for the clinician and reducing radiation exposure.

Methods and mechanisms for contact feedback in a robot-assisted minimally invasive environment

Providing a surgeon with information regarding contacts made between instruments and tissue during robot-assisted interventions can improve task efficiency and reliability. In this report, different methods for feedback of such information to the surgeon are discussed. It is hypothesized that various methods of contact feedback have the potential to enhance performance in a robot-assisted minimally invasive environment. To verify the hypothesis, novel mechanisms needed for incorporating contact feedback were designed, including a surgeon-robot interface with full force feedback capabilities and a surgical end-effector with full force sensing capabilities, that are suitable for minimally invasive applications. These two mechanisms were used to form a robotic "master-slave" test bed for studying the effect of contact feedback on the system and user performance. Using the master-slave system, experiments for surgical tasks involving soft tissue palpation were conducted. The performance of the master-slave system was validated in terms of criteria that assess the accurate transmission of task-related information to the surgeon, which is critical in the context of soft tissue surgical applications. Moreover, using a set of experiments involving human subjects, the performance of several users in carrying out the task was compared among different methods of contact feedback.

Multi-sensory force/deformation cues for stiffness characterization in soft-tissue palpation

In the commercially available robot-assisted surgical systems, camera vision constitutes the only flow of data from the patient side to the surgeon side. This paper studies how various modalities for feedback of interaction between a surgical tool and soft tissue can improve the efficiency of a typical surgical task. Utilizing a haptics-enabled master-slave test-bed for minimally invasive surgery, user performance during a telemanipulated soft tissue stiffness discrimination task is compared under visual, haptic, graphical, and graphical plus haptic feedback modes in terms of task success rate and completion time and the amount of energy transfer and consequently trauma to tissue. While no significant difference is found in terms of the task completion times, graphical cueing and visual cueing are found to lead to the highest success rate and the highest risk of tissue damage (proportional to energy), respectively.

Compartment syndromes

Compartment syndrome occurs when pressure within a closed muscle compartment exceeds the perfusion pressure and results in muscle and nerve ischaemia. Two distinct conditions are recognized: acute and chronic (exertional) compartment syndromes. Differences in aetiology, pathophysiology and management are elaborated on in this article.

Transcriptional Profiling of Pig Embryogenesis by Using a 15-K Member Unigene Set Specific for Pig Reproductive Tissues and Embryos1

Differential mRNA expression patterns were evaluated between germinal vesicle oocytes (pgvo), four-cell (p4civv), blastocyst (pblivv), and in vitro-produced four-cell (p4civp) and in vitro-produced blastocyst (pblivp) stage embryos to determine key transcripts responsible for early embryonic development in the pig. Five comparisons were made: pgvo to p4civv, p4civv to pblivv, pgvo to pblivv, p4civv to p4civp, and pblivv to pblivp. ANOVA (P < 0.05) was performed with the Benjamini and Hochberg false-discovery-rate multiple correction test on each comparison. A comparison of pgvo to p4civv, p4civv to pblivv, and pgvo to pblivv resulted in 3214, 1989, and 4528 differentially detected cDNAs, respectively. Real-time PCR analysis on seven transcripts showed an identical pattern of changes in expression as observed on the microarrays, while one transcript deviated at a single cell stage. There were 1409 and 1696 differentially detected cDNAs between the in vitro- and in vivo-produced embryos at the four-cell and blastocyst stages, respectively, without the Benjamini and Hochberg false-discovery-rate multiple correction test. Real-time polymerase chain reaction (PCR) analysis on four genes at the four-cell stage showed an identical pattern of gene expression as found on the microarrays. Real-time PCR analysis on four of five genes at the blastocyst stage showed an identical pattern of gene expression as found on the microarrays. Thus, only 1 of the 39 comparisons of the pattern of gene expression exhibited a major deviation between the microarray and the real-time PCR. These results illustrate the complex mechanisms involved in pig early embryonic development.

Haptic interaction and visualization of elastic deformation

In this paper, we represent a new method to model real-time local and global deformations on a variety of three-dimensional sculptured surfaces governed by physical principles. The deformable objects are highly elastic with linear behavior in the range of typical haptic forces. A deformation model is developed for incompressible material based on a mapping technique and the superposition principle. The law of energy conservation is used to calculate real-time force reflection. Using the divergence theorem, force reflection is calculated for volumetric deformations.

Haptic interaction in robot-assisted endoscopic surgery: a sensorized end-effector

Conventional endoscopic surgery has some drawbacks that can be addressed by using robots. The robotic systems used for surgery are still in their infancy. A major deficiency is the lack of haptic feedback to the surgeon. In this paper, the benefits of haptic feedback in robot-assisted surgery are discussed. A novel robotic end-effector is then described that meets the requirements of endoscopic surgery and is sensorized for force/ torque feedback. The endoscopic end-effector is capable of non-invasively measuring its interaction with tissue in all the degrees of freedom available during endoscopic manipulation. It is also capable of remotely actuating a tip and measuring its interaction with the environment without using any sensors on the jaws. The sensorized end-effector can be used as the last arm of a surgical robot to incorporate haptic feedback and/or to evaluate skills and learning curves of residents and surgeons in endoscopic surgery.

Neural network based tracking control of a flexible macro-micro manipulator system

In this paper, we address the problem of stable tracking control of a flexible macro-micro manipulator (M(3)) system. A two-layer neural network is utilized to approximate the nonlinear robot dynamic behavior of the M(3) system, and the controllers for the macro and micro arms are developed without any need for prior knowledge of the dynamic model of the controlled M(3) system. A learning algorithm for the neural network using Lyapunov stability theory is derived. It is shown that both the tracking error and the weight-tuning error are uniformly ultimately bounded under this new control scheme. Simulation results are presented and compared to those obtained using a PD controller.

Diagnosis and immediate care of fractures of the knee

In the UK the three commonest bony injuries around the knee are tibial plateau fractures, supracondylar and intercondylar fractures of the femur and patellar fractures. This review will summarize the initial management of these injuries and of rarer but significant more minor fractures that must not be missed. The review will concentrate on the injury to the knee, but every trauma patient must be assessed fully following advanced trauma life support guidelines.

Diagnosis and immediate care of soft tissue knee injuries

There is good evidence that the primary assessment of knee injuries is poor (Bollen and Scott, 1996). The knee is the most commonly injured joint in sport and exercise, and soccer and rugby carry the highest risk (Nicholl et al, 1991). A basic approach comprising a thorough history and a full examination, including ‘look, feel, move and special tests’, is usually all that is needed (Apley and Solomon, 1994).

Comparison of the durability of cadaveric and autologous fascia using an in vivo model

OBJECTIVES

To assess the durability of both autologous and cadaveric fascia using an animal model. The pubovaginal sling procedure can be performed using autologous, cadaveric, or synthetic materials. Few data are available about the strength and durability of these materials.

METHODS

Rectus abdominus fascia harvested from 6 female Sprague-Dawley rats was processed by Tutogen Medical. In 20 female Sprague-Dawley rats, three different types of fascia were implanted subcutaneously into each animal: autologous rectus abdominus fascia harvested at the time of surgery; rat cadaveric fascia processed by Tutogen; and human cadaveric fascia (Tutogen). The rats were killed at 2 months (10 rats) and 4 months (10 rats) after implantation. The mechanical properties of the tissue were assessed using the trouser tear test, and the fracture toughness was calculated.

RESULTS

Compared with the fracture toughness before implantation, the implanted rat autologous fascia decreased in toughness from 1763 to 1243 J/m(2) (P = 0.12), the implanted rat cadaveric fascia decreased in toughness from 1539 to 1022 J/m(2) (P = 0.02), and the implanted human cadaveric fascia decreased in toughness from 2120 to 1145 J/m(2) (P = 0.09). The fracture toughness of the implanted rat cadaveric fascia and rat autologous fascia did not differ significantly (P = 0.29).

CONCLUSIONS

The changes in strength or elasticity can be detected using the trouser tear test to calculate the fracture toughness. Both cadaveric and autologous fascial grafts may decrease in toughness with time. The long-term durability of the graft may only be a minor factor in determining the success of the pubovaginal sling procedure.

Regional structural and viscoelastic properties of fibrocartilage upon dynamic nanoindentation of the articular condyle

Fibrocartilage,a tissue with macromaterial properties between dense fibrous tissue and hyaline cartilage, is not well understood in its ultrastructure and regional viscoelastic properties. Here nanoindentation with atomic force microscopy was performed on fresh fibrocartilage samples of rabbit jaw joint condyles. Each sample was divided into anteromedial, anterolateral, posteromedial, and posterolateral regions for probing and topographic imaging in 2 x 2 microm and 10 x 10 microm scan sizes. Young's moduli differed significantly among these regions in a descending gradient from the anteromedial (2.34 +/- 0.26 MPa) to the posterolateral (0.95 +/- 0.06 MPa). The Poisson ratio, defined as lateral strain over axial strain, had the same gradient distribution: highest for the anteromedial region (0.46 +/- 0.05) and lowest for the posterolateral region (0.31 +/- 0.05). The same four regions showed a descending gradient of surface roughness: highest for the anteromedial (321.6 +/- 13.8 nm) and lowest for the posterolateral (155.6 +/- 12.6 nm). Thus, the regional ultrastructural and viscoelastic properties of fibrocartilage appear to be coregulated. Based on these region-specific gradient distributions, fibrocartilage is constructed to withstand tissue-borne shear stresses, which likely propagate across its different regions. A model of shear gradient and concentric gradient is proposed to describe the region-specific capacity of fibrocartilage to sustain shear stresses in tendons, ligaments, joints, and the healing bone across species.

Live-donor liver transplantation: the USC experience

BACKGROUND

Liver transplantation is currently the standard of care for patients with end stage liver disease. However due to the cadaveric organ shortage, live donor liver transplantation (LDLT), has been recently introduced as a potential solution. We analyzed and support our initial experience with this procedure at USC.

MATERIAL AND METHODS

From September 1998 until July 2000, a total of 27 patients underwent LDLT at USC University Hospital and Los Angeles Children's Hospital. There were 12 children with the median age of 10 months (4-114) and 15 adults with the median age of 56 years (35-65). The most common indication for transplantation was biliary atresia for children and hepatitis C for adults.

RESULTS

All donors did well postoperatively; the median postoperative stay was five days (5-7) for left lateral segmentectomy and seven days (4-12) for lobar donation. None of the donors required blood transfusion, re-operation or postoperative invasive procedure. However, five of them (18%) experienced minor complications. The survival rate in pediatric patients was 100% and only one graft was lost at nine months due to rejection. Two adult recipients died in the postoperative period, one from graft non-function and one from necrotizing fascitis. 37% of adult recipients experienced postoperative complications, mainly related to biliary reconstruction. Also 26% of the recipients underwent reoperation for some of these complications.

CONCLUSION

LDLT is an excellent alternative to cadaveric transplantation with excellent results in the pediatric population. However, in adult patients it still carries a significant complication rate and it should be used with caution.

Spontaneous expulsion of unusual tracheobronchial foreign body

An extremely rare case of long, thin and sharp pin in a young boy which was inhaled initially and defied removal at branchoscopy was eventually recovered in stool after a long and variable course through alimentary tract has been reported.

Practice patterns in the treatment of female urinary incontinence: a postal and internet survey

OBJECTIVES

To survey American urologists to assess practice patterns in treating female incontinence. Advances in the treatment of female incontinence have changed the way urologists practice.

METHODS

Postal and e-mail surveys were sent to 2502 members of the American Urological Association.

RESULTS

From the postal group (n = 1000), 419 (42%) responses were obtained; from the e-mail group (n = 1502), 160 (11%) responses were obtained. For types I, II, and III stress urinary incontinence (SUI), 239 (44%) of 546, 388 (68%) of 570, and 512 (94%) of 547 urologists, respectively, recommended a sling procedure. For type I SUI, 75 (53%) of the 143 respondents in practice for less than 10 years recommended a sling procedure. The sling was recommended by 62 (35%) of the 176 respondents in practice for longer than 20 years (P <0.001). Most urologists (75%, 358 of 480) referred patients with significant vaginal prolapse to a gynecologist; however, urologists in full-time academic practice were more likely to offer surgical treatment (56%, 29 of 52). Most urologists recommended medical treatment for urge incontinence (94%, 461 of 491), and the medications most commonly selected were tolterodine (41%, 202 of 491), oxybutynin (26%, 129 of 491), and extended-release oxybutynin (25%, 125 of 491).

CONCLUSIONS

Overall, a sling procedure was the most commonly recommended surgical procedure for all types of SUI. Most urologists referred patients with significant vaginal prolapse to a gynecologist. For type I SUI, older urologists were more likely than younger urologists to perform needle bladder neck suspension.

Use of new technology in endourology and laparoscopy by american urologists: internet and postal survey

OBJECTIVES

To assess the use of new technology by American urologists.

METHODS

Using the American Urological Association directory, surveys were sent via the U.S. postal service to 1000 randomly selected American urologists and 3065 urologists who had an Internet address listed in the directory.

RESULTS

Responses were received from 601 urologists (415 postal, 186 Internet). Overall, 81% of survey respondents reported performing fewer or the same number of percutaneous procedures as compared with 3 to 4 years ago and 84% reported carrying out more or the same number of ureteroscopic procedures in the treatment of patients with stone disease. Open dismembered pyeloplasty (43%) and Acucise endopyelotomy (42%) were most frequently reported as the preferred treatment for adult patients with symptomatic ureteropelvic junction obstruction. Although 60% of respondents reported that they have taken a laparoscopy course, 67% currently do not perform any laparoscopy in their practice. In addition, only 7% of urologists stated that laparoscopy comprises more than 5% of their practice. When stratified by the number of years in practice, those in practice less than 10 years were more likely than those in practice 10 to 20 years and those in practice longer than 20 years to have performed an endopyelotomy (77%, 60%, and 48%, respectively, P <0.001) and to be currently performing laparoscopy (49%, 36%, and 18%, respectively, P <0.001).

CONCLUSIONS

Compared with 3 to 4 years ago, American urologists are performing more ureteroscopy and fewer percutaneous stone procedures. Although most urologists have taken laparoscopy courses, this modality has not been widely incorporated into their practices at present.

Comparison of artificial urinary sphincter and collagen for the treatment of postprostatectomy incontinence

OBJECTIVES

To compare how urinary symptoms affect the quality of life in groups of men with postprostatectomy incontinence treated with collagen versus artificial urinary sphincter implantation.

METHODS

Two cohorts of men, one which received urethral collagen injection and one artificial urinary sphincter (AUS) implantation, were surveyed with a validated quality-of-life questionnaire to assess how their urinary dysfunction impacted their daily activities. The mean impact score and bother score for the two groups were compared. In addition, the overall degree of continence between the groups was assessed.

RESULTS

At a mean follow-up of 19 months, 8 (20%) of 41 patients treated with collagen injections were at least socially continent, requiring one pad daily or less. In comparison, 27 (75%) of 36 men treated with an AUS were at least socially continent (P <0.001). Both the impact score and the bother score from the quality-of-life questionnaire were significantly lower in the group treated with the AUS than in the group treated with collagen.

CONCLUSIONS

Patients receiving an AUS achieved significantly higher continence rates. Also, the quality of life of men treated with an AUS was improved compared with that of the men treated with collagen injection.

Internet and postal survey of endourologic practice patterns among American urologists

PURPOSE

We determine endourological practice patterns among American urologists for the management of distal ureteral calculi, ureteropelvic junction obstruction, staghorn calculi and the use of ureteral stents with extracorporeal shock wave lithotripsy (ESWLdagger).

MATERIALS AND METHODS

Surveys were mailed by the United States postal service to 1,000 American urologists selected randomly from the American Urological Association membership roster. The same survey was sent via the Internet to 3,065 American urologists with an electronic mail address listed in the roster.

RESULTS

Responses were received from 1,029 urologists (postal 601, Internet 428). Ureteroscopy was the preferred treatment for all distal ureteral calculi less than or equal to 10 mm. Acucisedouble dagger endopyelotomy was the most frequently selected therapy for adults with ureteropelvic junction obstruction (50.3%, 514 of 1,022). Open pyeloplasty was recommended by a significantly greater percentage of urologists in practice longer than 15 years compared with the remaining survey respondents (166 of 485, 34.2% versus 92 of 427, 21.5%). For patients with renal pelvic stones 10, 15 or 20 mm. who are treated with ESWL routine stent placement was preferred by 25.3% (259 of 1,022), 57.1% (584 of 1,022) and 87.1% (888 of 1, 019) of urologists, respectively. Percutaneous nephrolithotomy was preferred for patients with staghorn calculi by 80.5% (828 of 1,028) of survey respondents.

CONCLUSIONS

Most urologists follow the American Urological Association practice guidelines for patients with distal ureteral calculi and staghorn stones. There is a significant difference of opinion regarding the use of stents with ESWL. No clear consensus has been reached concerning the management of adults with ureteropelvic junction obstruction. These data may be useful in designing physician education programs and/or future investigations to help define standard treatment practices for urological diseases.

Characterization of gentamicin pharmacokinetics in patients hemodialyzed with high-flux polysulfone membranes

To characterize the pharmacokinetics of gentamicin during and after hemodialysis (using polysulfone Fresenius F-80 membranes (Fresenius USA, Inc, Walnut Creek, CA), surface area 1.6 m(2)), eight patients with end-stage renal disease undergoing chronic hemodialysis receiving the drug for therapeutic indications were enrolled. Intradialytic gentamicin half-life, clearance, and amount of gentamicin recovered during a hemodialysis session were also determined. Serum gentamicin concentrations were analyzed using fluorescence polarization immunoassay. The amount of gentamicin recovered was 64.3 +/- 14.4 mg, whereas the intradialytic gentamicin half-life was 2.24 +/- 0.83 hours, with a clearance of 116 +/- 9 mL/min. Gentamicin concentrations rebounded by 27.86% +/- 16.4% at 1. 5 +/- 0.52 hours after the end of the hemodialysis session. The decrease in gentamicin concentrations comparing maximum rebound to prehemodialysis concentrations was 53.54% +/- 9.97%. A variable yet substantial amount of gentamicin is removed during hemodialysis using F-80 membranes; hence, supplemental doses are necessary to avoid potential treatment failures. The supplemental doses of gentamicin calculated based on gentamicin concentrations obtained immediately postdialysis could be overestimated if the postdialysis rebound concentrations are not considered. A dosing regimen is suggested using the pharmacokinetic parameters defined by the present study and population estimate of volume of distribution.

Estimation of total body and extracellular water in post-coronary artery bypass graft surgical patients using single and multiple frequency bioimpedance

OBJECTIVE

To assess the value of bioimpedance as a clinical tool by determining the accuracy and bias of single and multiple frequency bioimpedance estimates of total body and extracellular water in comparison with values established by criterion reference techniques.

DESIGN

Controlled, prospective, single-blind investigation.

SETTING

Private, not-for-profit, university-affiliated, acute care hospital.

PATIENTS

Eight male, post-elective coronary artery bypass graft surgical patients.

INTERVENTIONS

Within 6 hrs after surgery, estimates of total body and extracellular water volumes were determined using single and multiple frequency bioimpedance techniques. These estimates were then compared with the gold standard volumes measured by deuterium oxide and bromine dilutional space determination, respectively.

MEASUREMENTS AND MAIN RESULTS

The mean multiple frequency bioimpedance estimate of total body water of 47.7 +/- 9.4 L was statistically different from the single frequency bioimpedance and deuterium values of 52.5 +/- 9.4 (p < .006) and 53.3 +/- 11.6 L (p < .002), respectively. In comparison, the mean multiple and single frequency bioimpedance estimates of extracellular water, 26.3 +/- 5.4 and 29.2 +/- 5.4 L, respectively, were not statistically different from the bromine value of 27.5 +/- 6.9 L. In addition, the mean errors for multiple and single frequency bioimpedance determinations of extracellular water, -1.2 +/- 2.0 and 1.7 +/- 2.7 L, respectively, were statistically different (p = .001).

CONCLUSIONS

In male, post-elective coronary artery bypass graft surgical patients, single frequency bioimpedance was a more accurate and less biased predictor of total body water than multiple frequency bioimpedance. The accuracy and bias of multiple frequency bioimpedance was superior to single frequency bioimpedance for the prediction of extracellular water. Whether this observation remains true for other populations of critically ill patients remains to be investigated.