Soft tissue modelling for haptic rendering in virtual environments

This paper focuses on the development of a haptic recording and modelling system. Currently being evaluated for multiple uses in surgery and manufacturing, this recording system evaluates haptic data captured via a robotic ann coupled with real time high-resolution load cell. This data is then analysed and validated against previous samples and a generated model before being logged for playback during simulation and training of a human operator. 3D models of point force interactions are created allowing unique visuals to be presented to a user. Primarily designed for the medical field, recorded results of soft tissue cutting have been presented.

Haptically simulating soft tissue using spherical voxel and reactive agents

This thesis describes technology developed by the author enabling trainee surgeons to perform needle insertion procedures with force feedback (haptics) on a virtual patient. Addition of the sense of touch to medical simulation is arguably the most important step forward in the evolution of haptic technology to this day.

Soft tissue characterisation using a force feedback-enabled instrument for robotic assisted minimally invasive surgery systems

An automated laparoscopic instrument capable of non-invasivemeasurement of tip/tissue interaction forces for direct application in robotic assisted minimally invasive surgery systems is introduced in this chapter. It has the capability to measure normal grasping forces as well as lateral interaction forces without any sensor mounted on the tip jaws. Further to non-invasive actuation of the tip, the proposed instrument is also able to change the grasping direction during surgical operation. Modular design of the instrument allows conversion between surgical modalities (e.g., grasping, cutting, and dissecting). The main focus of thispaper is on evaluation of the grasping force capability of the proposed instrument. The mathematical formulation of fenestrated insert is presented and its non-linear behaviour is studied. In order to measure the stiffness of soft tissues, a device was developed that is also described in this chapter. Tissue characterisation experiments were conducted and results are presented and analysed here. The experimental results verify the capability of the proposed instrument in accurately measuring grasping forces and in characterising artificial tissue samples of varying stiffness.

Clinical MRSA isolates from skin and soft tissue infections show increased in vitro production of phenol soluble modulins

BACKGROUND: Phenol-soluble modulins (PSMs) are amphipathic, pro-inflammatory proteins secreted by most Staphylococcus aureus isolates. This study tested the hypothesis that in vitro PSM production levels are associated with specific clinical phenotypes. METHODS: 177 methicillin-resistant S. aureus (MRSA) isolates from infective endocarditis (IE), skin and soft tissue infection (SSTI), and hospital-acquired/ventilator-associated pneumonia (HAP) were matched by geographic origin, then genotyped using spa-typing. In vitro PSM production was measured by high performance liquid chromatography/mass spectrometry. Statistical analysis was performed using Chi-squared or Kruskal-Wallis tests as appropriate. RESULTS: Spa type 1 was significantly more common in SSTI isolates (62.7% SSTI; 1.7% IE; 16.9% HAP; p < 0.0001) while HAP and IE isolates were more commonly spa type 2 (0% SSTI; 37.3% IE; 40.7% HAP; p < 0.0001). USA300 isolates produced the highest levels of PSMs in vitro. SSTI isolates produced significantly higher quantities of PSMα1-4, PSMβ1, and δ-toxin than other isolates (p < 0.001). These findings persisted when USA300 isolates were excluded from analysis. CONCLUSIONS: Increased in vitro production of PSMs is associated with an SSTI clinical source. This significant association persisted after exclusion of USA300 genotype isolates from analysis, suggesting that PSMs play a particularly important role in the pathogenesis of SSTI as compared to other infection types.

Increased versican content is associated with tendinosis pathology in the patellar tendon of athletes with jumper

Expansion of the extracellular matrix is a prominent but poorly characterized feature of tendinosis. The present study aimed to characterize the extent and distribution of the large aggregating proteoglycan versican in patients with patellar tendinosis. We obtained tendon from tendinopathy patients undergoing debridement of the patellar tendon and from controls undergoing intramedullary tibial nailing. Versican content was investigated by Western blotting and immunohistochemistry. Microvessel thickness and density were determined using computer-assisted image analysis. Markers for smooth muscle actin, endothelial cells (CD31) and proliferating cells (Ki67) were examined immunohistochemically. Western blot analysis and immunohistochemical staining revealed elevated versican content in the proximal patellar tendon of tendinosis patients (P=0.042). Versican content was enriched in regions of fibrocartilage metaplasia and fibroblast proliferation, as well as in the perivascular matrix of proliferating microvessels and within the media and intima of arterioles. Microvessel density was higher in tendinosis tissue compared with control tissue. Versican deposition is a prominent feature of patellar tendinosis. Because this molecule is not only a component of normal fibrocartilagenous matrices but also implicated in a variety of soft tissue pathologies, future studies should further detail both pathological and adaptive roles of versican in tendons.

Changes in body composition as determinants of longitudinal changes in bone mineral measures in 8 to 26 year old female twins

Between 1990 and 1998, we conducted a longitudinal study of 286 female twins aged 8 to 25 years at baseline (60 monozygotic (MZ) pairs, 44 dizygotic (DZ) pairs and 78 unpaired twins), measured on average 2.4 times (range 2–6) with an average of 1.8 years between measurements (range 0.7–6.7 years). Areal bone mineral density (ABMD) at the lumbar spine, total hip and femoral neck, total body bone mineral content (BMC), total body soft tissue composition (lean mass and fat mass) were measured by dual-energy X-ray absorptiometry, and height and menarchial status were also recorded. Median annual changes in height were negligible at 4 years post-menarche. During the “linear growth” period up to 4 years post-menarche, ABMD at the lumbar spine, total hip and femoral neck increased with annual change in lean mass by 1.7 (S.E. 0.1), 1.4 (0.1) and 1.0 (0.1) percent per kilogram per year, respectively (all p<0.001), independently of changes in fat mass or height. During the “post-linear growth” period, ABMD at the total hip and femoral neck increased with annual change in fat mass by 0.3 (0.1) and 0.5 (0.1) percent per kilogram per year (all p<0.01), independent of change in lean mass. Annual changes in total body BMC were associated with annual changes in lean mass (1.9 (0.2) percent per kilogram), in fat mass (1.3 (0.2) percent per kilogram) and in height (0.7) (0.2) percent per centimeter) during linear growth, and in fat mass (1.0 (0.1)) and lean mass (0.6 (0.1)) percent per kilogram post-linear growth (all p<0.001). We conclude that changes in bone mineral measures are strongly associated with changes in lean mass during linear growth, while post-linear growth, changes in fat mass are the predominant, although weaker, predictor. These findings suggest that the strong cross-sectional association between bone mineral measures and lean mass is established during growth and development, and that fat mass emerges as a more powerful determinant of bone change in healthy adult females.

Factors associated with chronic plantar heel pain: a systematic review

Chronic plantar heel pain (CPHP) is one of the most common soft tissue disorders of the foot, yet its aetiology is poorly understood. The purpose of this systematic review was to examine the association between CPHP and the various aetiological factors reported in the literature. Seven electronic databases and the reference lists of key articles were searched in August 2005. The resulting list of articles was assessed by two independent reviewers according to pre-determined selection criteria and a final list of articles for review was created. The methodological quality of the included articles was assessed and the evidence presented in each of the articles was descriptively analysed. From the 16 included articles, body mass index in a non-athletic population and the presence of calcaneal spur were the two factors found to have an association with CPHP. Increased weight in a non athletic population, increased age, decreased ankle dorsiflexion, decreased first metatarsophalangeal joint extension and prolonged standing all demonstrated some evidence of an association with CPHP. Evidence for static foot posture and dynamic foot motion was inconclusive and height, weight and BMI in an athletic population were not associated with CPHP. The findings of this review should be used to guide the focus of prospective cohort studies, the results of which would ultimately provide a list of risk factors for CPHP. Such a list is essential in the development of new and improved preventative and treatment strategies for CPHP.

Age does not influence the bone response to treadmill exercise in female rats

Purpose: Because it is believed that bone may respond to exercise differently at different ages, we compared bone responses in immature and mature rats after 12 wk of treadmill running.

Methods: Twenty-two immature (5-wk-old) and 21 mature (17-wk-old) female Sprague Dawley rats were randomized into a running (trained, N = 10 immature, 9 mature) or a control group (controls, N = 12 immature, 12 mature) before sacrifice 12 wk later. Rats ran on a treadmill five times per week for 60-70 min at speeds up to 26 m[middle dot]min-1. Both at baseline and after intervention, we measured total body, lumbar spine, and proximal femoral bone mineral, as well as total body soft tissue composition using dual-energy x-ray absorptiometry (DXA) in vivo. After sacrificing the animals, we measured dynamic and static histomorphometry and three-point bending strength of the tibia.

Results: Running training was associated with greater differences in tibial subperiosteal area, cortical cross-sectional area, peak load, stiffness, and moment of inertia in immature and mature rats (P < 0.05). The trained rats had greater periosteal bone formation rates (P < 0.01) than controls, but there was no difference in tibial trabecular bone histomorphometry. Similar running-related gains were seen in DXA lumbar spine area (P = 0.04) and bone mineral content (BMC;P = 0.03) at both ages. For total body bone area and BMC, the immature trained group increased significantly compared with controls (P < 0.05), whereas the mature trained group gained less than did controls (P < 0.01).

Conclusion: In this in vivo model, where a similar physical training program was performed by immature and mature female rats, we demonstrated that both age groups were sensitive to loading and that bone strength gains appeared to result more from changes in bone geometry than from improved material properties.

Protein nutrition in fibromyalgia

Background: Fibromyalgia (FM) is a soft-tissue disease of unknown origin. It causes soft-tissue pain and stiffness, often with chronic fatigue, disrupted sleep, headaches and irritable bowel. Fibromyalgia affects an estimated six million Americans of which 80 to 90 percent are female.

Objective: To determine whether dietary intake of protein, Tryptophan, and Branched Chain Amino Acids (BCAA) meet Dietary Reference Intake (DRI) recommendations, and whether there is a difference in animal and vegetable protein intake in subjects with FM compared to healthy controls.

Methods: Thirty subjects with FM and an equal number of controls completed a Food Frequency Questionnaire (FFQ) regarding dietary intake over the previous month. The FFQs were then computer analyzed to determine dietary intake.

Results: Protein intake of all subjects was more than adequate to meet DRI recommendations and there was no significant difference in intake of protein, BCAA, Tryptophan, animal or vegetable protein. Subjects with FM had significantly higher body weight and Body Mass Index (BMI) than controls, and reported having a higher incidence of Irritable Bowel Syndrome (IBS) symptoms than controls.

Conclusion: There was no significant difference in dietary intake of protein, Tryptophan, BCAA, or amounts of animal or vegetable protein in FM subjects compared to healthy controls. Significant differences in body weight and BMI in FM subjects might be related to less physical activity or possibly to malabsorption problems associated with IBS. Malabsorption related to IBS might increase the potential for protein malnutrition, FM, and associated symptoms like chronic fatigue.

Pain relief for the removal of femoral sheath in interventional cardiology adult patients (Review)

Pain relief for removal of femoral sheath after cardiac procedures
Procedures for the non-surgical management of coronary heart disease include balloon angioplasty and intracoronary stenting. At the start of each procedure an introducer sheath is inserted through the skin (percutaneously) into an artery, frequently a femoral artery in the groin. This allows the different catheters used for the procedure to be exchanged easily without causing trauma to the skin. At the end of the procedure the sheath is removed and, if the puncture site isn't "sealed" using a device closure, firm pressure is required over the site for 30 minutes or more to control any bleeding and reduce vascular complications. Removing the sheath and the firm pressure required to control bleeding can cause pain, although this is generally mild. Some centres routinely give pain relief before removal such as intravenous morphine, or an injection of a local anaesthetic in the soft tissue around the sheath (called a subcutaneous injection). Adequate pain control during sheath removal is also associated with a reduced incidence of a vasovagal reaction, a potentially serious complication involving a sudden drop of blood pressure and a slowed heart rate. Four studies were reviewed in total. Three trials involving 498 participants compared subcutaneous lignocaine, a short acting local anaesthetic, with a control group (participants received either no pain relief or an inactive substance known as a placebo). Two trials involving 399 people compared intravenous opioids (fentanyl or morphine) and an anxiolytic (midazolam) with a control group. One trial involving 60 people compared subcutaneous levobupivacaine, a long acting local anaesthetic, with a control group. Intravenous pain regimens and subcutaneous levobupivacaine appear to reduce the pain experienced during femoral sheath removal. However, the size of the reduction was small. A significant reduction in pain was not experienced by participants who received subcutaneous lignocaine or who were in the control group. There was insufficient data to determine a correlation between pain relief administration and either adverse events or complications. Some patients may benefit from routine pain relief using levobupivacaine or intravenous pain regimens. Identifying who may potentially benefit from pain relief requires clinical judgement and consideration of patient preference. The mild level of pain generally experienced during this procedure should not influence the decision as some people can experience moderate levels of pain.

Unintentional needlestick injuries in livestock production : a case series and review

Livestock producers and their employees sometimes experience unintentional needlestick injury (NSI) while vaccinating or injecting medications into animals. There is little published regarding the medical complications that can develop from this occupational exposure. The objectives of this study were to (1) perform a retrospective review of animal-related NSIs treated at a tertiary medical center of a rural state; and (2) review the risks of NSI and measures to decrease their occurrence. Medical records of patients with NSI related to animal injection were identified from the University of Iowa Hospitals and Clinics database from 2002 to 2008 and reviewed. Nine patients received medical care for NSI that occurred while vaccinating farm animals. Most common NSI site was the nondominant hand and most occurred while attempting to inject the animal. Soft tissue infection was common and all nine received oral and/or intravenous antibiotics. Two thirds required hospital admission. Three required surgery and one had a bedside incision and drainage procedure. One patient had a serious inflammatory reaction with necrosis in the leg due to the oil adjuvant in the animal vaccine. Another case had a probable mycetoma with osteomyelitis and soft tissue infection due to the bacteria Streptomyces, which is a NSI complication not previously reported. Although medical complications from farm-related NSIs do not appear to be common, this case series illustrates how these injuries can be debilitating, costly, and lead to loss of work time and productivity. Producers and employees who inject livestock need to be aware of the risks and utilize measures to decrease unintentional NSI.

Risk factors for Mycobacterium ulcerans infection, southeastern Australia

Buruli/Bairnsdale ulcer (BU) is a severe skin and soft tissue disease caused by Mycobacterium ulcerans. To better understand how BU is acquired, we conducted a case-control study during a sustained outbreak in temperate southeastern Australia. We recruited 49 adult patients with BU and 609 control participants from a newly recognized BU-endemic area in southeastern Australia. Participants were asked about their lifestyle and insect exposure. Odds ratios were calculated by using logistic regression and were adjusted for age and location of residence. Odds of having BU were at least halved for those who frequently used insect repellent, wore long trousers outdoors, and immediately washed minor skin wounds; odds were at least doubled for those who received mosquito bites on the lower legs or lower arms. This study provides new circumstantial evidence that implicates mosquitoes in the transmission of M. ulcerans in southeastern Australia.

The influence of body build on estimates of body composition from anthropometric measurements in premenopausal women

Objective: To assess the influence of body build on the bias and limits of agreement for estimates of body fat obtained from anthropometric prediction equations when compared with the same data obtained by dual energy X-ray absorptiometry (DEXA).

Survey design and subjects: Ninety-one premenopausal women, aged between 20 and 54 years, were chosen to represent a range of skeletal body build (relative silting height 0.50-0.56) and body fatness [body mass index (BMI) 18-34 kg/m²]. Measurements of weight, sitting height, stature, skinfold thickness, waist, umbilical and hip circumference and total body resistance and reactance were made on all subjects by standard techniques after an overnight fast. A DEXA measurement of total body fat, fat-free soft tissue and total body bone mineral mass was also obtained within 2 weeks of the anthropometric assessment.

Results: At the group level the mean difference (bias) between DEXA and the anthropometric estimates of body fat was similar for all three anthropometric estimates ranging from 2.7 kg with impedance to 1.8 kg with skinfold thickness. The 95% limits of agreement were also similar, ranging from ±5.3 kg with body mass index to ±4.1 kg with impedance. Umbilical circumference, BMI and the amount of bone mineral expressed as a proportion of the fat-free soft-tissue mass were all significantly (P < 0.01) correlated with the level of bias between DEXA and the anthropometric estimates of body fat. This was not the case for relative sitting height or measures of body fat distribution. Regression equations which included BMI or umbilical circumference in combination with the predicted estimates of body fat essentially eliminated the association between the level of bias in predicted body fat and the level of body fatness. They also reduced the 95% limits of agreement between DEXA and the anthropometric estimates of body fat.

Conclusions: Using DEXA estimates of body fat as the standard of reference our results suggest that the comparability and precision of body fat estimates derived from age- and/or sex-specific anthropometric prediction equations based on skinfolds and BMI, but not impedance, can be improved by adjusting for differences in BMI and umbilical circumference respectively.

3D fibrous structures as cardiovascular implants

Medical textiles are a highly specialised stream of technical textiles industry with a growing range of applications. A significant advancement has been achieved in surgical products or biomedical textiles (implantable/non-implantable) with the advent of 3D textile manufacturing techniques. Cardiovascular soft tissue implants (vascular grafts) have been a field of interest over decades for use of innovative 3D tubular structures in treatment of cardiovascular diseases. In the field of soft tissue implants, knitted and woven tubular structures are being used for large diameter blood vessel replacements. Advent of electrospinning and tissue engineering techniques has been able to provide promising answers to small diameter vascular grafts. The aim of this review is to outline the approaches in vascular graft development utilising different 3D tubular structure forming techniques. The emphasis is on vascular graft development techniques that can help improve treatment efficacy in future.