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Preoperative serial imaging of the torso is typically carried out in the supine position (e.g. magnetic resonance imaging [MRI], CT), however, intraoperative patient positioning is often lateral, and for some procedures may involve deflation and/or ventilation of the lungs. This study examined the differences in lung anatomy between the supine and lateral decubitus positions. MRI data for 10 healthy female adult volunteers lying in supine and left lateral decubitus positions were analysed. 2D measurements in coronal, transverse and sagittal planes were used to calculate the cross-sectional area, height and width of the lungs and the shape of the diaphragm. 3D surface reconstructions of the lungs and bronchi were created to determine the volume change between positions. The volume of the right lung was found to increase due to the caudal shift of the insertion points of the right hemidiaphragm (mean volume increase of 25% ± 11, p ≪ 0.05). There was minimal change in the left lung parameters with no significant change in left lung volume between positions (mean volume change = 0% ± 44%, p > 0.05). This study presents new information characterising anatomical changes in the respiratory system when a patient is positioned in the lateral decubitus compared to supine position.

Background Paediatric scoliosis is a common condition seen by general practitioners. Structural scoliosis is characterised by axial rotation at the apex. Several new operative treatments have recently been developed. Objective The aim of this article is to give an overview of scoliosis diagnosis, assessment and management. Discussion Scoliosis assessment should identify structural curves, underlying causes, severity and growth potential. Atypical curves and red flags must be excluded. Observation is appropriate for curves 40°. Surgery can be divided into three groups: growth modulation, instrumentation without fusion and instrumentation with fusion. Early diagnosis and referral to a paediatric spine service can improve outcomes.

Background Low back pain (LBP) is a common presentation in general practice. Clinical workup must exclude sinister underlying diseases. Treatment of central LBP is difficult given the numerous treatment options available. Objective The aim of this article is to help clinicians assess patients with LBP and formulate evidence-based treatment decisions. Discussion Patient presentations can be stratified according to the presence of red flags and pain type (ie non-spinal, radicular, non‑organic and central). The vast majority of patients with acute central back pain experience improvement of their symptoms. Treatment options include education, lifestyle modification, heat, massage, graduated return to early activity, nonsteroidal anti-inflammatory medications and muscle relaxants when appropriate. Chronic LBP treatment can also include paracetamol and physiotherapy. Second-line treatment can include psychological therapy, multidisciplinary rehabilitation, targeted injections and antidepressants. Tapentadol is a safe and effective medication for treating severe LBP. Pain specialist referral should be considered if patients require controlled analgesia. Surgical treatment has narrow indications in central non-radicular back pain and is considered as a last-line treatment in selected patients.

Background: Many pathogens of importance, including the staphylococcal species of concern in orthopaedics, demonstrate seasonal variations influenced by environmental factors. The aim of this study was to investigate the role of humidity as a risk factor for deep prosthetic joint infection following total knee arthroplasty (TKA) in a tropical Australian hospital. Methods: A retrospective cohort study of all TKAs performed over a 13-year period was conducted at the author's institution. Univariate analysis was used to individually assess for a range of risk factors including humidity >60% and apparent temperature >30°C (86°F). Odds ratios (ORs) were reported. P-values 60% (OR 1.4; 95% confidence interval (CI) 0.68–3.04; P = 0.221); (ii) apparent temperature >30°C (86°F) (OR 2.4; 95% CI 0.56–10.1; P = 0.174); (iii) male gender (OR 2.2; 95% CI 1.02–4.81; P = 0.057); and (iv) American Society of Anesthesiologists score of III or IV (OR 2.1; 95% CI 1.00–4.49; P = 0.064). Conclusion: Humidity and apparent temperature may be potentially important risk factors for infection following TKA.

Background: Major lower limb amputation is occasionally required in the management of end-stage pathology where other treatment options have failed. The primary aim of this study was to determine the 30-day and 1-year mortality rates of patients undergoing nontraumatic major lower limb amputation. Secondary aims were to investigate risk factors for poor outcomes, incidence of previous minor amputation, and the rate of subsequent major amputation. Methods: All nontraumatic, major lower limb amputations performed at Toowoomba Hospital during an 18-year period were retrospectively reviewed. Mortality data were obtained from the Queensland Registry of Births, Deaths and Marriages. Kaplan–Meier analysis was performed to determine survival after amputation. Results: A total of 147 patients were included in the study, with 104 undergoing below knee and 43 undergoing above knee amputations. Ten patients identified as having an Aboriginal and Torres Strait Islander background. For all patients, the 30-day mortality was 4.1% and 1-year mortality was 21.1%. For Indigenous patients, 30-day mortality was 10%. Previous minor amputation had occurred in 40 patients. Twenty-nine patients underwent further minor surgery after their initial major amputation, with thirteen requiring subsequent major amputation. Factors that increased mortality risk were the presence of peripheral vascular disease, an American Society of Anesthesiologists score of four and age greater than 65 years. Conclusion: The morbidity and mortality following major lower limb amputation is significant. The findings of this study highlight the importance of preventative measures to minimize the incidence of lower limb amputations in the future.

Background. Morton’s neuroma is a common cause of forefoot pain. Outcomes of conservative therapy are mixed and many patients undergo operative intervention. Radiofrequency ablation has recently gained favor as a treatment option, although the optimal regime is unknown. This study investigates the effectiveness of 2 versus 3 cycles of radiofrequency ablation for the treatment of Morton’s neuroma. Methods. We surveyed a cohort of patients with Morton’s neuroma who had progressed to radiofrequency ablation after failed conservative treatment. Patients received either 2 or 3 cycles of radiofrequency ablation by a single surgeon. We assessed patients based on their change in numerical pain rating scale, symptom improvement, complications, and progression to surgical excision through a series of telephone interviews. Outcomes between the 2 treatment arms were compared by parametric tests. Results. Twenty-eight patients were included in the study. Eighteen patients with 21 neuromas received 2 cycles and 10 patients with 11 neuromas received 3 cycles. Mean time of follow-up was 12.9 months. Overall, 88% of patients were either very or moderately satisfied with their outcome. In patients who received 2 cycles mean numerical pain scores decreased from 7.9 ± 1.1 to 3.4 ± 2.4 postprocedure. Three patients progressed to operative excision. In patients who received 3 cycles, numerical pain scores decreased from 8.0 ± 1.0 to 1.5 ± 2.0 postprocedure. One patient progressed to operative excision. Patients who received 3 cycles had reduced medium-term pain postoperatively compared with 2 cycles (3.4 ± 2.4 vs 1.5 ± 2.0, P = .011). Conclusion. Radiofrequency ablation provides a high rate of patient satisfaction in the treatment of Morton’s neuroma with few side effects. It appears that 3 cycles may be superior to 2 cycles but a randomized controlled trial will be required to confirm these results. Levels of Evidence: Intervention, Level III: Comparative study without concurrent controls

Aim: First we aimed to assess the reproducibility of a computer tomography angiography (CTA) based technique for measuring infra-renal aortic volume and diameter. Second we sought to investigate whether changes in aortic volume and diameter were similar during follow-up. Materials and methods: A prospective series of 57 patients, with aortic diameter initially measuring between 25 and 55 mm, were assessed with 2 CTAs a median of 14 months apart. Aortic volume and maximum diameter (both axial and orthogonal) were measured by a semi-automated workstation protocol based on previously defined techniques. Intra- and inter-observer reproducibility were assessed by repeat assessment of the initial CTA images of the first 33 patients included in the study, in order to estimate the 95% limits of agreements. Changes in aortic dimensions between the first and follow-up CTA, were defined for volume and diameter separately as changes greater than their respective 95% limits of agreement. Results: Reproducibility of aortic volume and diameter was excellent with an average coefficient of variation

Background Patients with abdominal aortic aneurysms (AAA) are predisposed to cardiovascular events and often experience continual expansion of their aneurysm. Cardiovascular events and expansion rates are positively correlated with aneurysm size. AAA is usually associated with intraluminal thrombus, which has previously been implicated in AAA pathogenesis. This study prospectively assessed the association of infrarenal abdominal aortic thrombus volume with cardiovascular events and AAA growth. Methods Ninety-eight patients with AAAs underwent computed tomography angiography (CTA). The volume of infrarenal aorta thrombus was measured by a previously validated technique. Patients were monitored prospectively for a median of 3 years (interquartile range [IQR], 2.0-3.6 years), and cardiovascular events (nonfatal stroke, nonfatal myocardial infarction, coronary revascularization, amputation, and cardiovascular death) were recorded. Of the original patients, 39 underwent repeat CTA a median of 1.5 years (IQR, 1.1-3.3 years) after entry to the study. Kaplan-Meier and Cox proportional analysis were used to examine the association of aortic thrombus with cardiovascular events and average weighted AAA growth. Results There were 28 cardiovascular events during follow-up. The incidence of cardiovascular events was 23.4% and 49.2% for patients with small (smaller than the median) and large (median or larger) volumes of aortic thrombus, respectively, at 4 years ( P = .040). AAA thrombus volume of median or larger was associated with increased cardiovascular events (relative risk [RR] 2.8, 95% confidence interval [CI], 1.01-5.24) independent of other risk factors, including initial AAA diameter, but was only of borderline significance when patients were censored at the time of AAA repair (RR, 2.35; 95% CI, 0.98-5.63). In the subset of patients with CTA follow-up, the median annual increase in AAA volume was 5.1 cm 3 (IQR, 0.8-10.3 cm 3 ). Annual AAA volume increase was positively correlated with initial AAA diameter ( r = 0.44, P = .006) and thrombus volume ( r = 0.50, P = .001). Median or larger aortic thrombus volume was associated with rapid AAA volume increase (≥5 cm/y), independent of initial aortic diameter (RR, 15.0; 95% CI, 1.9-115.7; P = .009). Conclusion In this small cohort, infrarenal aortic thrombus volume was associated with the incidence of cardiovascular events and AAA progression. These results need to be confirmed and mechanisms underlying the associations clarified in large further studies.

Intra-luminal thrombus has been suggested to play a role in the progression of abdominal aortic aneurysm (AAA). The aims of this study were twofold. Firstly, to assess the reproducibility of a computer tomography (CT)-based technique for measurement of aortic thrombus volume. Secondly, to examine the determinants of infrarenal aortic thrombus volume in a cohort of patients with aortic dilatation. A consecutive series of 75 patients assessed by CT angiography with maximum aortic diameteror = 25 mm were recruited. Intra-luminal thrombus volume was measured by a semi-automated workstation protocol based on a previously defined technique to quantitate aortic calcification. Intra- and inter-observer reproducibility were assessed using correlation coefficients, coefficient of variation and Bland-Altman plots. Infrarenal aortic thrombus volume percentage was related to clinical, anatomical and blood characteristics of the patients using univariate and multivariate tests. Infrarenal aortic thrombus volume was related to the severity of aortic dilatation assessed by total aortic volume (r = 0.87, P0.0001) or maximum aortic diameter (r = 0.74, P0.0001). We therefore examined the clinical determinates of aortic thrombus expressed as a percentage of total aortic volume. Aortic thrombus percentage was negatively correlated with serum high density lipoprotein (HDL, r = -0.31). By ordinal multiple logistic regression analysis serum HDL below median (or = 1.2 mM: ) was associated with aortic thrombus percentage in the upper quartile adjusting for other risk factors (odds ratio 5.3, 95% CI 1.1-25.0). Infrarenal aortic thrombus volume can be measured reproducibly on CT. Serum HDL, which can be therapeutically raised, may play a role in discouraging aortic thrombus accumulation with implications in terms of delaying progression of AAA.

Objectives: During total knee replacement (TKR) surgery, the most commonly used method for aligning the distal femur appropriately is via an intramedullary (IM) distal femoral alignment rod. The alignment of the rod itself is reliant on the isthmus which is used to most accurately place the rod in the correct anatomical axis. In the instance of something preventing the rod from entering the isthmus correctly, such as a hip replacement, then the degree of accuracy could be assumed to be even less. Mechanical-anatomical malalignment has been shown to decrease the implant (TKR) survival and so methods of increasing accuracy of alignment relative to the mechanical axis have been developed. At present the most accurate method intraoperatively is computer navigation and several studies have demonstrated improved alignment. An increasing number of patients year on year are having both knee and hip replacements and as the population ages the likelihood of having both a knee and hip replacement will also increase. We propose that the presence of a hip replacement within the isthmus of the femur may further decrease the accuracy of the IM alignment of the femur leading to incorrect implant positioning. Methods: The study was conducted on 10 cadaveric specimens (20 femurs). Computational navigation instrumentation was attached in turn to each femur and the ideal alignment data recorded in a standard fashion by a single operator (principal investigator). A standard entry port was then be made in the femur for the introduction of the IM rod. An IM rod was then inserted with the distal femoral cutting block in the accepted position recorded blindly on the computer navigation (both in terms of varus/valgus alignment to the mechanical axis and the degree of flexion). The process was then repeated at 3 levels to represent primary and revision hip lengths from the greater trochanter (replicating the changes that would occur in the presence of a hip replacement) The process was recorded three times at each level. Results: The resection angles between the cutting surface and the mechanical axis were measured and collected by means of computer navigation system. The results show that the IM alignment had mean Valgus of 0 degrees +/- 0.8 but with a hip replacement in situ this increased to 0.46 degrees +/- 1.49 (range 2.5 varus to 4.5 valgus), with a revision stem 0.825 +/- 1.68 (range 2.5 varus to 4.5 valgus) and long stemmed revision 1.325 +/- 2.09 (range 5 varus to 6.5 valgus). In terms of Flexion IM alignment had a mean flexion of 0.92 +/- 1.7 (range 3 extension to 4 flexion) but with a hip replacement in situ this increased to 1.88 degrees +/- 2.03 (range 2.5 extension to 8.5 flexion), with a revision stem 2.35 +/- 2.2 (range 2.5 extension to 8 flexion) and long stemmed revision 2.75 +/- 2.16 (range 3.5 extension to 7 flexion). Conclusion: This Study concludes that the prescence of a hip replacement, in particular long stemmed prosthesis, further reduces the accuracy of IM alignment in the Femur for Total Knee Replacement. Consideration of an alternative method, such as navigation, should be considered in such situations.

Obesity and arterial calcification are associated with increased cardiovascular morbidity and mortality. The relationship between obesity and abdominal aortic calcification has been under investigated. The majority of research has focused on the relationship between clinical anthropometric measures and aortic calcification, with mixed results. Numerous calcification measurement protocols have hindered appropriate analysis of the literature. However, recently a reproducible computed tomography method for aortic calcification quantification has been published. Similarly, many methods are available for anthropometric assessment. Clinical measures include body mass index, waist circumference, waist to hip ratio, skin fold and percent body fat. Alternatively, computed tomography can be reproducibly utilized to measure abdominal adipose diameters, area and volume. Recently, the relationship between calcification and anthropometric measurements has been investigated by computed tomography. It was found that a measure of visceral adiposity was associated with abdominal aortic calcification. In addition, visceral adiposity was positively and negatively correlated to circulating concentrations of osteoprotegerin and leptin, respectively. This has provided a possible pathogenic mechanism for the accumulation of abdominal aortic calcification. The aims of this chapter are two fold: 1. To outline the various anthropometric and calcification protocols currently employed for vascular research. 2. To review the current literature regarding the relationship between anthropometric measures and abdominal aortic calcification.

To assess the association of circulating bone marrow-derived osteo-progenitors with vascular calcification in mouse models and patients with peripheral artery disease.We estimated the percentage of circulating mononuclear cells expressing osteocalcin in 2 mouse models of aortic calcification developed in osteoprotegerin-deficient mice (OPG(-/-)) using flow cytometry. Aortic calcification was assessed in mice principally by a bioassay of harvested aortas. In patients with peripheral artery disease osteocalcin-positive cells (estimated by flow cytometry) were related to aortic calcification volume assessed from computed tomography.The amount of extractable aortic calcium was increased in both mouse models used in comparison to controls. The percentage of circulating mononuclear cells expressing osteocalcin was correlated to the amount of extractable aortic calcium in male (r=0.525, p=0.02) and female OPG(-/-) (r=0.564, p=0.02) mice and also in animals in which calcification was accelerated using calcitriol (r=0.64, p=0.01). Patients with more severe aortic calcification had a greater percentage of circulating OCN(+) MNCs (median 4.07%, IQR 3.76-4.39, n=12) than those with less severe aortic calcification (median 3.10%, IQR 2.32-3.60, n=11, p=0.05).This study demonstrates that aortic calcification can be robustly quantified in 2 mouse models. In these models and patients with peripheral artery disease circulating osteocalcin positive mononuclear cells are associated with the severity of aortic calcification.

In patients with peripheral artery disease, aortic calcific deposits are a common finding. The aim of this study was to assess the association of infrarenal abdominal aortic calcific deposits with prospective cardiovascular events in patients with peripheral artery disease. A consecutive series of 213 patients who presented for investigation of abdominal aortic aneurysm or intermittent claudication were assessed using computed tomographic angiography. Infrarenal abdominal aortic calcific deposits were estimated using a previously defined highly reproducible semiautomated program. Patients were followed prospectively for a median of 2.8 years (interquartile range 1.7 to 3.6), and cardiovascular events were recorded. Kaplan-Meier and Cox proportional-hazards analysis were used to examine the association of calcific deposits with cardiovascular events. A total of 45 cardiovascular events occurred during follow-up, including nonfatal myocardial infarction (n = 23), coronary revascularization (n = 6), stroke (n = 3), below-knee amputation (n = 2), and cardiovascular death (n = 11). The incidence of cardiovascular events was 21.7%, 33.0%, and 36.9% for patients with mild (400 mm(3)), intermediate (400 to 1,700 mm(3)), and severe (1,700 mm(3)) abdominal aortic calcific deposits, respectively (p = 0.039). Calcific deposit volume400 mm(3) (relative risk 2.8, 95% confidence interval 1.2 to 6.6) and coronary artery disease (relative risk 2.8, 95% confidence interval 1.4 to 5.6) were independently associated with increased cardiovascular events during follow-up. In conclusion, abdominal aortic calcific deposits are prognostic for cardiovascular events in patients with peripheral artery disease.

To the Editor: We read with great interest the recent publication by Dr Lindholt1. In this study the severity of aortic calcification was inversely correlated with the growth rate of small abdominal aortic aneurysms (AAA). The author’s finding fits with a recent study by our group demonstrating that AAA growth was reduced in diabetic patients2. In vitro studies suggested that cross-linkage of the extracellular matrix in diabetic patients’ favoured de-activation of infiltrating monocytes, thereby inhibiting medial degradation2. It would be interesting to know if the association between calcification and AAA growth noted in the study by Dr Lindholt persisted after adjusting for diabetes. Dr Lindholt used assessment of aortic calcification measured on ultrasound as > or < 50% of an unspecified denominator. We have previously developed a technique to measure aortic calcification volume by a reproducible method on computed tomography angiography (CTA) (inter- and intra-observer coefficient of variation < 1%)3. This technique would be expected to be more objective than ultrasound measurements although to completely assess this both techniques would need to be repeated on the same patient cohort and compared. We have recently assessed the relationship between initial infrarenal aortic calcification volume and yearly increase in total aortic volume in a cohort of 32 patients with small AAAs (

Background: The role of homocysteine in atherosclerosis is unclear.We examined the relationship between plasma homocysteine and infrarenal aortic calcification, the presence of homocysteine in human atheroma and the influence of homocysteine on osteogenic differentiation in vitro. Methods and results: In 194 patients with symptomatic peripheral artery disease or abdominal aortic aneurysm, fasting plasma total homocysteine was independently associated with the severity of infrarenal aortic calcification measured by Computer Tomography Angiography (odds ratio 1.91, 95% confidence interval 1.17–3.21 for calcification ≥median). Homocysteine was identified in all 60 atheroma biopsies from 16 patients undergoing endarterectomy, and concentrations were significantly greater in the calcified biopsies (p = 0.003). In vitro studies demonstrated that 100 mol/L homocysteine doubled the calcium deposition by mesenchymal stem cells during 16 days incubation in osteogenic medium (74±4 compared to 42±5g calcium/well without homocysteine, p < 0.001). Homocysteine also stimulated monocytic THP1 cells to promote aortic smooth muscle cell calcification as evidenced by significant higher calcium deposition and alkaline phosphatase activity compared to incubation without homocysteine (p≤0.05). Conclusions: Homocysteine plays an important role in vascular calcification via multiple mechanisms. The presence of homocysteine in atheroma and its ability to enhance osteogenic cell differentiation may partly explain the association of homocysteine with atherosclerotic events.

Background: Visceral obesity and aortic calcification are both associated with cardiovascular events. The purpose of this study was to examine if visceral obesity was associated with the severity of abdominal aortic calcification. Methods: One hundred and forty eight patients with peripheral artery disease were assessed by CT angiography. The severity of infrarenal abdominal aortic calcification was measured using a validated technique. The size of the visceral and subcutaneous compartments was estimated from anthropometric measurements made from the same CT. Calcification and anthropometric measurements were compared with Spearman's correlation and multiple logistic regression (adjusting for age, gender, hypertension, diabetes, smoking and cholesterol). Results: The relative size of the visceral compartment estimated from CT diameter ratios was correlated with abdominal aortic calcification severity, r = 0.27, p = 0.001 and independently associated with calcification allowing for other cardiovascular risk factors (OR 6.63, 95% CI 1.90–23.14). The relative size of the visceral compartment was associated with serum osteoprotegerin levels, suggesting a possible mechanism underlying the detrimental influence of visceral adiposity. Conclusion: The association of visceral adiposity and arterial calcification suggests one mechanism, which may contribute to the detrimental effects of central obesity.

Abdominal aortic aneurysm (AAA) affects approximately 5% of men and 1% of women over 60 years, and the incidence is increasing.1 The principal complication of AAA is aortic rupture, which usually results in death.2 Rupture risk is presently best predicted by aortic diameter, with AAAs >6 cm having a rupture risk of approximately 10% per year.3 Since AAA is usually asymptomatic, the condition is often diagnosed as an incidental finding during abdominal imaging. Recently, a number of randomized controlled trials have demonstrated that ultrasound screening of selected population can reduce deaths associated with AAA.4,5 The more widespread use of ultrasound screening and abdominal imaging has led to an increase in the number of small AAAs referred for management. Two randomized trials have supported a conservative policy for small AAAs, whereby following identification aneurysms are followed by ultrasound surveillance unless the aneurysm expands to >5.5 cm in maximal diameter when surgery is advised.6,7 The introduction of endovascular aneurysm repair (EVAR) has made available a less invasive surgical option, which had been demonstrated to be associated with lower perioperative mortality than open surgery for the repair of large aneurysms.8,9 However, EVAR has a number of complications that only become apparent during longer-term follow-up, such as late aortic rupture, endoleak, graft migration, and graft limb occlusion.10,11 Intermediate follow-up of patients randomized to EVAR for the treatment of large AAAs demonstrated no reduction in all-cause mortality in comparison to open surgery and increased requirement for reintervention.10,11 The favorable perioperative results, the greater anatomic suitability and the belief that the outcome of EVAR is better have all encouraged the extension of this technique to patients normally treated conservatively with small AAAs. The aim of this study was to examine the perioperative and intermediate results of EVAR for AAAs of ≤5.5 cm.