Australasian Malignant PLeural Effusion (AMPLE)-4 trial: study protocol for a multi-centre randomised trial of topical antibiotics prophylaxis for infections of indwelling pleural catheters.

BACKGROUND: Malignant pleural effusion (MPE) is a debilitating condition as it commonly causes disabling breathlessness and impairs quality of life (QoL). Indwelling pleural catheter (IPC) offers an effective alternative for the management of MPE. However, IPC-related infections remain a significant concern and there are currently no long-term strategies for their prevention. The Australasian Malignant PLeural Effusion (AMPLE)-4 trial is a multicentre randomised trial that evaluates the use of topical mupirocin prophylaxis (vs no mupirocin) to reduce catheter-related infections in patients with MPE treated with an IPC. METHODS: A pragmatic, multi-centre, open-labelled, randomised trial. Eligible patients with MPE and an IPC will be randomised 1:1 to either regular topical mupirocin prophylaxis or no mupirocin (standard care). For the interventional arm, topical mupirocin will be applied around the IPC exit-site after each drainage, at least twice weekly. Weekly follow-up via phone calls or in person will be conducted for up to 6 months. The primary outcome is the percentage of patients who develop an IPC-related (pleural, skin, or tract) infection between the time of catheter insertion and end of follow-up period. Secondary outcomes include analyses of infection (types and episodes), hospitalisation days, health economics, adverse events, and survival. Subject to interim analyses, the trial will recruit up to 418 participants. DISCUSSION: Results from this trial will determine the efficacy of mupirocin prophylaxis in patients who require IPC for MPE. It will provide data on infection rates, microbiology, and potentially infection pathways associated with IPC-related infections. ETHICS AND DISSEMINATION: Sir Charles Gairdner and Osborne Park Health Care Group Human Research Ethics Committee has approved the study (RGS0000005920). Results will be published in peer-reviewed journals and presented at scientific conferences. TRIAL REGISTRATION: Australia New Zealand Clinical Trial Registry ACTRN12623000253606. Registered on 9 March 2023.

A 6-year experience of Zephyr endobronchial valves for severe emphysema in an Australian single-centre cohort.

BACKGROUND: Endobronchial valve (EBV) insertion for lung volume reduction is a management option for patients with severe emphysema. One-way valves cause lobar deflation and improve lung function, exercise capacity and quality of life. AIMS: To retrospectively analyse and compare the outcomes of the first 57 patients treated with EBVs between 2015 and 2021 at the Royal Adelaide Hospital to international standards. METHODS: Clinical outcomes of forced expiratory volume in 1 s (FEV1), residual volume (RV), treated lobe volume reduction (TLVR) and 6-min walk distance (6MWD) at 3, 6 and 12 months after valve insertion were reviewed against established minimally clinically important differences (MCIDs). Complications and subjective breathlessness measured by Borg scores were also reviewed. RESULTS: Fifty-seven patients were included. At 12 months, 77.2% achieved TLVR. FEV1 improved by 170 mL (95% confidence interval (CI): 100-250, P < 0.001), 80 mL (95% CI: 10-150, P = 0.019) and 40 mL (95% CI: -60 to 130, P 0.66) at 3, 6 and 12 months respectively. RV improved by -610 mL (95% CI: -330 to -900, P < 0.0001) at 3 months, -640 mL (95% CI: -360 to -920, P < 0.0001) at 6 months and -360 mL (95% CI: -60 to -680, P = 0.017) at 12 months. 6MWD improved by 57.34 m (95% CI: 36.23-78.45, P < 0.0001) and 44.93 m (95% CI: 7.19-82.67, P = 0.02) at 3 and 6 months. Borg score improved by -0.53 (95% CI: 0.11 to -1.2, P = 0.11) and -0.49 (95% CI: 0.17 to -1.15, P = 0.16) at 3 and 6 months. Complication rates aligned with international standards with mucous/infection (26.3%) and pneumothorax (17.5%) as the most common. Subgroup analysis signalled improved outcomes in patients with heterogeneous emphysema. CONCLUSION: Our study represents the first publicly funded Australian analysis of EBVs. The results align with international prospective trials demonstrating improved lung function and exercise capacity. Australians with severe emphysema and gas trapping should be referred to a multidisciplinary centre for consideration of EBVs.

Associations of physical activity and quality of life in parapneumonic effusion patients.

Introduction: Little is known about activity behaviours and quality of life (QoL) of patients with parapneumonic pleural effusions (PPE) after hospital discharge. This study is a secondary analysis of a randomised trial (dexamethasone versus placebo) for hospitalised patients with PPE. We: 1) described the patients' activity behaviour patterns and QoL measured at discharge and at 30 days post-discharge; and 2) examined the association between activity behaviours and QoL scores. Methods: Activity behaviour (7-day accelerometry; Actigraph GT3X+) and QoL (Medical Outcomes Study Short-Form 36) were assessed. Repeated measures analysis of covariance controlling for baseline values and a series of linear regression models were undertaken. Results: 36 out of 53 eligible participants completed accelerometry assessments. Despite modest increases in light physical activity (+7.5%) and some domains of QoL (>2 points) from discharge to 30 days post-discharge, patients had persistently high levels of sedentary behaviour (>65% of waking wear time) and poor QoL (≤50 out of 100 points) irrespective of treatment group (p=0.135-0.903). Increasing moderate-to-vigorous physical activity was associated with higher scores on most QoL domains (p=0.006-0.037). Linear regression indicates that a clinically important difference of 5 points in physical composite QoL score can be achieved by reallocating 16.1 min·day-1 of sedentary time to moderate-to-vigorous physical activity. Conclusion: Patients with PPE had low levels of physical activity and QoL at discharge and 30 days post-discharge irrespective of treatment. Moderate-to-vigorous physical activity participation was associated with higher QoL scores. Increasing moderate-to-vigorous physical activity following discharge from the hospital may be associated with improvements in QoL.

First Asia-Pacific experience of trans-bronchial core biopsy with a Franseen needle.

Background: Endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) is the standard for evaluating mediastinal and hilar lesions. EBUS-TBNA is limited by small volume of material obtained for immunohistochemistry (IHC) and ancillary studies important for oncological therapies. The Franseen AcquireTM needle is designed for EBUS-transbronchial needle core biopsy (TBNB) allowing larger core sizes with evidence in gastroenterology literature but little in pulmonology. This study reports the first Asia-Pacific experience of EBUS-TBNB and adequacy of samples for diagnosis and ancillary studies. Methods: A retrospective cohort study of EBUS-TBNB at the Royal Adelaide Hospital was conducted between December 2019 and May 2021. Diagnostic rate, adequacy for ancillary studies and complications were evaluated. Samples were flushed into formalin for histological processing with no rapid on-site cytological evaluation (ROSE). For suspected lymphoma, samples were flushed into HANKS for flow cytometry. Cases performed with the Olympus VizishotTM during the same 18-month were similarly analysed. Results: One hundred and eighty-nine patients were sampled with the AcquireTM needle. Diagnostic rate was 174/189 (92.1%). Where reported [146/189 (77.2%)], average core aggregate sample size was 13.4 mm × 10.7 mm × 1.7 mm. For non-small cell lung cancer (NSCLC) cases, 45/49 (91.8%) had adequate tissue for programmed cell death-ligand 1 (PD-L1). 32/35 (91.4%) adenocarcinoma cases had sufficient tissue for ancillary studies. There was one false negative malignant lymph node at the first AcquireTM procedure. There were no major complications. One hundred and one patients were sampled with the VizishotTM needle. Diagnostic rate was 86/101 (85.1%) with only 25/101 (24.8%) having reported tissue cores (P<0.0001 of VizishotTM) with the remaining samples processed via cell block. Conclusions: AcquireTM EBUS-TBNB diagnostic rate is comparable to historical data with >90% of cases having sufficient core material for ancillary studies. There appears to be a role for the AcquireTM alongside the standard of care for the work up of lymphadenopathy and particularly for lung cancer.

Australasian Malignant PLeural Effusion (AMPLE)-3 trial: study protocol for a multi-centre randomised study comparing indwelling pleural catheter (±talc pleurodesis) versus video-assisted thoracoscopic surgery for management of malignant pleural effusion.

INTRODUCTION: Malignant pleural effusions (MPEs) are common. MPE causes significant breathlessness and impairs quality of life. Indwelling pleural catheters (IPC) allow ambulatory drainage and reduce hospital days and re-intervention rates when compared to standard talc slurry pleurodesis. Daily drainage accelerates pleurodesis, and talc instillation via the IPC has been proven feasible and safe. Surgical pleurodesis via video-assisted thoracoscopic surgery (VATS) is considered a one-off intervention for MPE and is often recommended to patients who are fit for surgery. The AMPLE-3 trial is the first randomised trial to compare IPC (±talc pleurodesis) and VATS pleurodesis in those who are fit for surgery. METHODS AND ANALYSIS: A multi-centre, open-labelled randomised trial of patients with symptomatic MPE, expected survival of ≥ 6 months and good performance status randomised 1:1 to either IPC or VATS pleurodesis. Participant randomisation will be minimised for (i) cancer type (mesothelioma vs non-mesothelioma); (ii) previous pleurodesis (vs not); and (iii) trapped lung, if known (vs not). Primary outcome is the need for further ipsilateral pleural interventions over 12 months or until death, if sooner. Secondary outcomes include days in hospital, quality of life (QoL) measures, physical activity levels, safety profile, health economics, adverse events, and survival. The trial will recruit 158 participants who will be followed up for 12 months. ETHICS AND DISSEMINATION: Sir Charles Gairdner and Osborne Park Health Care Group (HREC) has approved the study (reference: RGS356). Results will be published in peer-reviewed journals and presented at scientific meetings. DISCUSSION: Both IPC and VATS are commonly used procedures for MPE. The AMPLE-3 trial will provide data to help define the merits and shortcomings of these procedures and inform future clinical care algorithms. TRIAL REGISTRATION: Australia New Zealand Clinical Trial Registry ACTRN12618001013257 . Registered on 18 June 2018. PROTOCOL VERSION: Version 3.00/4.02.19.

Suboptimal COVID-19 vaccine uptake among hospitalised patients: an opportunity to improve vulnerable, hard-to-reach population vaccine rates.

BACKGROUND: COVID-19 vaccination represents a key preventative part of the Australian public health approach to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Hospital inpatients are frequently high risk for severe COVID-19 and death. Anecdotes of high-risk inpatients being unvaccinated and a lack of electronic medical record (EMR) visibility of COVID-19 vaccination status prompted the present study as these patients could represent a risk to themselves, staff, other patients and service provision. AIMS: To determine the uptake of COVID-19 vaccine among inpatients at an adult Australian tertiary public hospital and identify reasons for non-vaccination. METHODS: A point-prevalence study of patient-reported COVID-19 vaccine status was conducted on 26 October 2021 through an in-person interview with collection of demographic factors and reasons for non-vaccination. RESULTS: Of 368 (68% of inpatients) participants, 280 (76%) reported receiving at least one COVID-19 vaccine dose. Vaccination status was associated with older age, having received the flu vaccine, being born in Australia and not requiring an English-language interpreter. The majority (88%) of participants had at least one comorbid risk factor for severe COVID-19. Of the unvaccinated (n = 88), 67% were willing to be vaccinated with 54% of those indicating vaccination in hospital would be helpful and 42% requesting approval from their doctor. CONCLUSIONS: Vaccine uptake in our cohort is suboptimal. Existing public health programmes have failed to reach this high-risk, vulnerable population. Changes to the national vaccination strategy to include a parallel inhospital programme for all hospital encounters and target culturally and linguistically diverse individuals might improve uptake among this high-risk, hard-to-reach group of patients.

Steroid Therapy and Outcome of Parapneumonic Pleural Effusions (STOPPE): A Pilot Randomized Clinical Trial.

Rationale: Pleural effusion commonly complicates community-acquired pneumonia and is associated with intense pleural inflammation. Whether antiinflammatory treatment with corticosteroids improves outcomes is unknown. Objectives: To assess the effects of corticosteroids in an adult population with pneumonia-related pleural effusion. Methods: The STOPPE (Steroid Therapy and Outcome of Parapneumonic Pleural Effusions) trial was a pilot, multicenter, double-blinded, placebo-controlled, randomized trial involving six Australian centers. Patients with community-acquired pneumonia and pleural effusion were randomized (2:1) to intravenous dexamethasone (4 mg twice daily for 48 h) or placebo and followed for 30 days. Given the diverse effects of corticosteroids, a comprehensive range of clinical, serological, and imaging outcomes were assessed in this pilot trial (ACTRN12618000947202). Measurements and Main Results: Eighty patients were randomized (one withdrawn before treatment) and received dexamethasone (n = 51) or placebo (n = 28). This pilot trial found no preliminary evidence of benefits of dexamethasone in improving time to sustained (>12 h) normalization of vital signs (temperature, oxygen saturations, blood pressure, heart, and respiratory rates): median, 41.0 (95% confidence interval, 32.3-54.5) versus 27.8 (15.4-49.5) hours in the placebo arm (hazard ratio, 0.729 [95% confidence interval, 0.453-1.173]; P = 0.193). Similarly, no differences in C-reactive protein or leukocyte counts were observed, except for a higher leukocyte count in the dexamethasone group at Day 3. Pleural drainage procedures were performed in 49.0% of dexamethasone-treated and 42.9% of placebo-treated patients (P = 0.60). Radiographic pleural opacification decreased over time with no consistent intergroup differences. Mean duration of antibiotic therapy (22.4 [SD, 15.4] vs. 20.4 [SD, 13.8] d) and median hospitalization (6.0 [interquartile range, 5.0-10.0] vs. 5.5 [interquartile range, 5.0-8.0] d) were similar between the dexamethasone and placebo groups. Serious adverse events occurred in 25.5% of dexamethasone-treated and 21.4% of placebo-treated patients. Transient hyperglycemia more commonly affected the dexamethasone group (15.6% vs. 7.1%). Conclusions: Systemic corticosteroids showed no preliminary benefits in adults with parapneumonic effusions. Clinical trial registered with www.anzctr.org.au (ACTRN12618000947202).

A challenging diagnosis of malignant mesothelioma with osteosarcomatous differentiation metastasizing to bone.

Malignant pleural mesothelioma (MPM) is an insidious primary neoplasm of the pleura that can be challenging to diagnose and is commonly considered to be only locally invasive. We present the case of a 74-year-old male who presented with clinical features of MPM but from whom pleural fluid and biopsies initially suggested benign pathology. He later developed diffuse bony metastases and re-examination of pleural biopsies using modern immunohistochemistry and molecular testing revealed a diagnosis of sarcomatoid and desmoplastic MPM with heterologous osteosarcomatous differentiation. This case not only demonstrates the rare potential of skeletal metastasis of MPM, but also highlights the importance of recognizing the utility of modern diagnostic tests and their potential to prevent the need for unnecessary invasive procedures. To our knowledge this is the first description of this rare histological sub-type presenting with skeletal metastases.

Use of indwelling pleural/peritoneal catheter in the management of malignant ascites: a retrospective study of 48 patients.

BACKGROUND: Patients suffering from malignant ascites usually require repeated large volume paracentesis (LVP) for symptomatic relief. This often requires hospital admission and has inherent risks. AIMS: To report the first Australian experience of placing tunnelled indwelling peritoneal catheters (IPeC) for management of recurrent malignant ascites. METHODS: A retrospective study was conducted of tunnelled IPeC use in patients with symptomatic malignant ascites in four hospitals in Western Australia (from 2010 to 2018). Procedure data, success rate and safety profile were collected from a database. RESULTS: Forty-eight patients (median age 65 years; female 56%) underwent 51 peritoneal catheter insertion procedures that were performed mostly by pleural specialists. The majority of patients (96%) had prior LVP (median two drainages, interquartile range (IQR) 1-4) before IPeC insertion. The IPeC was inserted successfully under ultrasound guidance in all patients. The median length of hospital stay for IPeC insertion and initial ascites drainage was 2 days (IQR 2-3 days) and most patients (96%) did not require further paracentesis after IPeC placement. The majority (96%) of patients experienced relief from ascites symptoms after catheter insertion. Most IPeC-related adverse events were self-limiting, including pain (in 25% cases), transient hypotension after initial fluid drainage (10%), peritoneal fluid leakage (10%), bacterial peritonitis (8%), fluid loculation (2%) and catheter dislodgement (2%). Six (12%) patients had IPeC removed. All patients with bacterial peritonitis responded to antibiotics and one required catheter removal. CONCLUSIONS: Use of tunnelled IPeC improves symptoms and can minimise further invasive drainage procedures in patients with symptomatic malignant ascites. Placement of IPeC was associated with a low rate of adverse events, most of which could be managed conservatively.

Advances in pathological diagnosis of mesothelioma: what pulmonologists should know.

PURPOSE OF REVIEW: Malignant pleural mesothelioma (MPM) is a universally fatal illness with a rising incidence, particularly in developing countries. The diagnosis can be challenging and require repeated investigations with implications for the patient and healthcare system. RECENT FINDINGS: Distinguishing between benign/reactive and malignant mesothelial proliferations can be challenging. Cytological diagnosis of MPM from pleural fluid is as reliable as histological analysis of tissue biopsies in epithelioid MPM - an approach endorsed by the International Academy of Cytology. Identification of BRCA1-associated protein 1 (BAP1) and cyclin-dependent kinase inhibitor 2A (CDKN2A) gene mutations in MPM have led to the development of new ancillary tests that can streamline the diagnostic pathway. The prognostic values of these molecules are being investigated. Clinicians should be aware of the recently described BAP1 tumor predisposition syndrome and offer genetic investigations in potential patients. Routine use of prophylactic radiotherapy in MPM patients after pleural interventions has been disproved in a randomized trial. SUMMARY: Diagnosis of epithelioid MPM can be established on pleural fluid analysis in most patients. The use of BAP1 immunostaining and CDKN2A/p16 fluorescence in-situ hybridization are particularly useful in distinguishing benign from malignant mesothelial proliferations. Clinicians should ensure these investigations are available in the pathological assessment of cases to minimize invasive investigations and the associated risks.

Pleural empyema in a patient with a perinephric abscess and diaphragmatic defect.

Pleural infection as a complication of ascending urological infection is rare, and the mechanism often unclear. We report a complicated case of pleural infection and perinephric abscess in a patient who presented with a large right-sided pleural effusion. Pleural fluid culture yielded Morganella morganii, an unusual pathogen in pleuro-pulmonary infections. Her computed tomography (CT) scan of abdomen showed a right perinephric abscess which extended into the pleural cavity. Review of prior CT imaging suggested a pre-existing diaphragmatic defect, likely representing a congenital Bochdalek foramen, through which the infection ascended. Successful treatment was achieved with systemic antibiotics, and drainage of both the pleural and retroperitoneal collections. Intra-pleural tissue plasminogen activator/deoxyribonuclease therapy effectively cleared the residual pleural fluid. Spread of intra-abdominal sepsis through diaphragmatic defects to the pleural cavity represents a potential source of empyema.

Successful management of pleural infection with very low dose intrapleural tissue plasminogen activator/deoxyribonuclease regime.

Pleural infection managed with intrapleural therapy using a combination of 10 mg of tissue plasminogen activator (tPA) and 5 mg of deoxyribonuclease (DNase) has been shown in randomized and open-label studies to successfully treat >90% of patients without resorting to surgery. Potential bleeding risks, although low, and costs associated with tPA remain important concerns. No phase I studies exist for intrapleural tPA therapy and the lowest effective dose has not been established. In patients with high bleeding risks, lower doses may present a safer alternative. We report a case of a complex parapneumonic effusion in a patient with coagulopathy that was successfully treated with a very low dose tPA (1 mg) and DNase (5 mg) regime.

Radial Endobronchial Ultrasound Greyscale Texture Analysis Using Whole-Lesion Analysis Can Characterise Benign and Malignant Lesions without Region-of-Interest Selection Bias.

BACKGROUND: Radial-probe endobronchial ultrasound (RP-EBUS) is predominantly used clinically for the localisation of peripheral pulmonary lesions prior to biopsy. However, the RP-EBUS image itself contains information that can characterise the aetiology of lesions. OBJECTIVES: The aim of this study was to show the utility of RP-EBUS image analysis using unconstrained regions of interest (ROIs) that utilise more image information and eliminate ROI selection bias. METHODS: We developed custom software to analyse RP-EBUS images digitally captured during clinical procedures. Unconstrained ROIs were mapped onto lesions. We computed first-order greyscale image statistics of minimum, maximum, mean, standard deviation and range of pixel intensities, and entropy. We also computed second-order greyscale texture features of contrast, correlation, energy and homogeneity. The results of image analysis were compared to gold-standard tissue diagnosis. Features from expert- and non-expert-defined ROIs were also compared. RESULTS: Eighty-five images were analysed (38 benign and 47 malignant). Five greyscale features were significantly different between benign and malignant lesions. Benign lesions had higher mean (p < 0.01) and maximal (p < 0.001) intensity, greater range (p < 0.001) of pixel intensities and greater entropy (p < 0.01). The highest positive predictive values were associated with maximal (87.8%) and range of pixel (83.8%) intensities. There were no significant differences between expert- and non-expert-defined ROIs. CONCLUSION: RP-EBUS image analysis using unconstrained ROIs eliminates ROI selection bias and can characterise benign and malignant lesions with an accuracy of up to 85%.

Zinc deficiency as a codeterminant for airway epithelial barrier dysfunction in an ex vivo model of COPD.

There is now convincing evidence that the airway epithelium drives the pathogenesis of COPD. A major aspect of this is the disease-related reduction in barrier function that is potentiated by dysregulation of tight junction (TJ) protein complexes. However, a significant number of studies using in vitro smoke exposure models have not observed alterations in barrier permeability. We have previously shown that zinc (Zn) is an influential cytoprotective factor for the airway epithelium, and its depletion by cigarette smoke produces disease-related modifications consistent with inflammatory changes in COPD. We hypothesized that Zn deficiency is a significant co-stimulus with cigarette smoke extract (CSE) for potentiating the leaky barrier phenotype exhibited in COPD. We employed an ex vivo model of differentiated human airway epithelium exposed to Zn depletion and CSE to determine the contribution of Zn in maintaining normal epithelial permeability. Western blot analysis demonstrated a significant downregulation of the TJ proteins such as ZO-1 (-1.93-fold, P<0.05) and Claudin-1 (-3.37-fold, P<0.01) with the combination exposure. Assessment of barrier function via paracellular ionic conductance and tracer permeability also showed that Zn depletion was an important factor, which potentiated an increase in epithelial permeability (P<0.001 for both) compared to Zn depletion or CSE exposures in isolation. Visual inspection of the epithelium using transmission electron microscopy revealed a marked reduction in junction complexes between the adjacent airway epithelial cells treated with a combination of Zn depletion and CSE. These observations identify Zn deficiency as a significant codeterminant with CSE as a factor leading to an increase in airway epithelial permeability. Hence, as Zn dyshomeostasis has been reported in the airway epithelium exposed to chronic cigarette smoke and inflammation, targeting these phenomena may represent a promising strategy to ameliorate the leaky barrier phenotype that is synonymous with COPD.

A model for the change of cancellous bone volume and structure over time.

A model is presented for characterizing the process by which cancellous bone changes in volume and structure over time. The model comprises simulations of local changes resulting from individual remodelling events, known as bone multicellular units (BMU), and an ordinary differential equation for connecting the number of remodelling events to real time. The model is validated on micro-CT scans of tibiae of normal rats, estrogen deprived rats and estrogen deprived rats treated with bisphosphonates. The model explains the asymptotic trends seen in changes of bone volume over time resulting from estrogen deprivation as well as trends seen subsequent to treatment. The model demonstrates that both bone volume and structure changes can be explained in terms of resetting remodelling parameters. The model also shows that either current understanding of the effects of bisphosphonates is not correct or that the simplest description of remodelling does not suffice to explain both the change in bone volume and structure of rats treated with bisphosphonates.

Increased proportion of hypermineralized osteocyte lacunae in osteoporotic and osteoarthritic human trabecular bone: implications for bone remodeling.

Hypermineralized osteocyte lacunae (micropetrosis) have received little research attention. While they are a known aspect of the aging human skeleton, no data are available for pathological bone. In this study, intertrochanteric trabecular bone cores were obtained from patients at surgery for osteoporotic (OP) femoral neck fracture (10F, 4M, 65-94 years), for hip osteoarthritis (OA; 7F, 8M, 62-87 years), and femora at autopsy (CTL; 5F, 11M, 60-84 years). Vertebral trabecular bone cores were also obtained from the vertebra of autopsy cases (CVB; 3F, 6M, 53-83 years). Specimens were resin-embedded, polished, and carbon coated for quantitative backscattered electron imaging (qBEI), energy dispersive X-ray (EDX) spectrometry, and imaging analysis. Bone mineralization (Wt %Ca) was not different between OP, OA, and CTL; but was greater in femoral CTL than in CVB. The percent of hypermineralized osteocyte lacunae relative to the total number (HL/TL) was greater in OP and OA than in CTL. However, relative to bone mineral area, OP was characterised by increased hypermineralized osteocyte lacunar number density (Hd.Lc.Dn), whereas OA was characterised by decreased osteocyte lacunar number density (Lc.Dn) and total osteocyte lacunar number density (Tt.Lc.Dn). Lc.Dn was higher in CVB than in femoral CTL. The calcium-phosphorus ratio (R(Ca/P)) was not different between hypermineralized osteocyte lacunae and bone matrix in each group. In addition, this study focused on the phenomenon of osteocyte lacunae hypermineralization using qBEI. Seven morphological types of osteocyte lacunae hypermineralization were described according to the presence of one or several hypermineralized spherites, associated or not with a hypermineralized lacunar ring. This study has described, for the first time, the morphology of hypermineralized osteocyte lacunae in OP and OA human bone. Further studies are suggested to investigate the functional influence of hypermineralized osteocyte lacunae on bone remodeling and bone biomechanical properties.

Influence of orthogonal overload on human vertebral trabecular bone mechanical properties.

UNLABELLED: The aim of this study was to investigate the effects of overload in orthogonal directions on longitudinal and transverse mechanical integrity in human vertebral trabecular bone. Results suggest that the trabecular structure has properties that act to minimize the decrease of apparent toughness transverse to the primary loading direction. INTRODUCTION: The maintenance of mechanical integrity and function of trabecular structure after overload remains largely unexplored. Whereas a number of studies have focused on addressing the question by testing the principal anatomical loading direction, the mechanical anisotropy has been overlooked. The aim of this study was to investigate the effects of overload in orthogonal directions on longitudinal and transverse mechanical integrity in human vertebral trabecular bone. MATERIALS AND METHODS: T(12)/L(1) vertebral bodies from five cases and L(4)/L(5) vertebral bodies from seven cases were retrieved at autopsy. A cube of trabecular bone was cut from the centrum of each vertebral body and imaged by microCT. Cubes from each T(12)/L(1) and L(4)/L(5) pairs were assigned to either superoinferior (SI) or anteroposterior (AP) mechanical testing groups. All samples were mechanically tested to 10% apparent strain by uniaxial compression according to their SI or AP allocation. To elucidate the extent to which overload in orthogonal directions affects the mechanical integrity of the trabecular structure, samples were retested (after initial uniaxial compression) in their orthogonal direction. After mechanical testing in each direction, apparent ultimate failure stresses (UFS), apparent elastic moduli (E), and apparent toughness moduli (u) were computed. RESULTS: Significant differences in mechanical properties were found between SI and AP directions in both first and second overload tests. Mechanical anisotropy far exceeded differences resulting from overloading the structure in the orthogonal direction. No significant differences were found in mean UFS and mean u for the first or second overload tests. A significant decrease of 35% was identified in mean E for cubes overloaded in the SI direction and then overloaded in the AP direction. CONCLUSIONS: Observed differences in the mechanics of trabecular structure after overload suggests that the trabecular structure has properties that act to minimize loss of apparent toughness, perhaps through energy dissipating sacrificial structures transverse to the primary loading direction.