Increased PI3K pathway activity is associated with recurrent breast cancer in patients with low and intermediate 21-gene recurrence score.

AIMS: We investigated key signalling pathways' activity and mutational status of early-stage breast carcinomas with low and intermediate 21-gene recurrence score (RS) to identify molecular features that may predict recurrence. METHODS: This is a retrospective case-control study of 18 patients with recurrent breast carcinoma with low and intermediate 21-gene RS (<25) and control group of 15 non-recurrent breast cancer patients. DNA and mRNA were extracted from tumour tissue. mRNA expression of genes involved in oestrogen receptor (ER), androgen receptor (AR), PI3K and MAPK signalling pathways was measured by real-time quantitative reverse transcription-qPCR (OncoSIGNal G4 test, InnoSIGN). Tumour mutational landscape was assessed by targeted DNA sequencing (Oncomine Precision Assay). RESULTS: There were no statistical differences between the groups' demographic and clinicopathological characteristics. PI3K pathway showed significantly higher activity in cases compared with controls (p=0.0014). Receiver operating characteristic curve analysis showed an area under the curve of 0.79 for PI3K pathway activity in the prediction of recurrent disease in low and intermediate 21-gene RS breast cancer. There was no difference in ER, AR and MAPK pathway activity. PIK3CA alterations were the most common driver mutations, but no difference was found between the groups (p=0.46) and no association with PI3K pathway activity (p=0.86). Higher Ki67 gene expression was associated with recurrences (p=0.042) CONCLUSION: Increased PI3K pathway activity, independent of PIK3CA mutations, may play a role in the recurrence of early-stage breast cancer with low and intermediate 21-gene RS. Pathway analysis can help to identify high-risk patients in this setting.

Genetic and Immunohistochemical Profiling of Mammary Hidradenoma and Comparison to Mucoepidermoid Carcinoma.

Mucoepidermoid carcinoma (MEC) is exceedingly rare in the breast, with <45 cases reported in the literature. Although estrogen receptor/progesterone receptor/human epidermal growth factor 2 triple-negative, MEC is characterized as a special subtype of breast carcinoma with significantly better prognosis than conventional basal-type tumors. Cutaneous hidradenoma (HA) is considered a benign adnexal neoplasm showing histomorphologic overlap with MEC. Rare cases of HA have also been reported in the breast, but these are relatively uncharacterized. In this study, we examined the clinicopathologic, immunohistochemical (IHC), and genetic features of 8 breast HAs, in comparison to 3 mammary MECs. All cases were positive for MAML2 break-apart fluorescence in situ hybridization. Eight cases demonstrated a CRTC1::MAML2 fusion, and one MEC harbored a CRTC3::MAML2 fusion; the latter is a novel finding in the breast. Mutational burden was very low, with only one HA exhibiting a MAP3K1 pathogenic alteration. By IHC, both MEC and HA demonstrated cell type-dependent expression of high- and low-molecular-weight keratins and p63, as well as negative to low-positive estrogen receptor and androgen receptor. Smooth muscle myosin and calponin highlighted an in situ component in the 3 cases of MEC; expression of these myoepithelial markers was negative in HAs. Additional distinguishing characteristics included the growth pattern and tumor architecture, the presence of glandular/luminal cells in HA, and overall higher IHC expression of SOX10, S100 protein, MUC4, and mammaglobin in MEC. Morphologic findings were also compared to a series of 27 cutaneous nonmammary HAs. Mucinous and glandular/luminal cells were identified in significantly more mammary HAs than nonmammary lesions. The findings provide insight into the pathogenesis of MAML2-rearranged neoplasms of the breast, underscore the overlapping genetic features of MEC and HA, and highlight similarities to their extramammary counterparts.

Optimization of Thymidine Kinase-Based Safety Switch for Neural Cell Therapy.

Cell therapies based on pluripotent stem cells (PSC), have opened new therapeutic strategies for neurodegenerative diseases. However, insufficiently differentiated PSC can lead to tumor formation. Ideally, safety switch therapies should selectively kill proliferative transplant cells while preserving post-mitotic neurons. In this study, we evaluated the potential of nucleoside analogs and thymidine kinase-based suicide genes. Among tested thymidine kinase variants, the humanized SR39 (SR39h) variant rendered cells most sensitive to suicide induction. Unexpectedly, post-mitotic neurons with ubiquitous SR39h expression were killed by ganciclovir, but were spared when SR39h was expressed under the control of the cell cycle-dependent Ki67 promoter. The efficacy of six different nucleoside analogs to induce cell death was then evaluated. Penciclovir (PCV) showed the most interesting properties with an efficiency comparable to ganciclovir (GCV), but low toxicity. We tested three nucleoside analogs in vivo: at concentrations of 40 mg/kg/day, PCV and GCV prevented tumor formation, while acyclovir (ACV) did not. In summary, SR39h under the control of a cell cycle-dependent promoter appears most efficient and selective as safety switch for neural transplants. In this setting, PCV and GCV are efficient inducers of cell death. Because of its low toxicity, PCV might become a preferred alternative to GCV.

Diagnosis of soft tissue tumors using immunohistochemistry as a surrogate for recurrent fusion oncoproteins.

Soft tissue neoplasms encompass a broad spectrum of clinicopathologic manifestations. In a subset of soft tissue tumors, spanning a wide range of clinical behavior from indolent to highly aggressive, recurrent genetic translocations yield oncogenic fusion proteins that drive neoplastic growth. Beyond functioning as primary mechanisms of tumorigenesis, recurrent translocations represent key diagnostic features insofar as the presence of a particular oncogenic gene fusion generally points to specific tumor entities. In addition to more direct methods for identifying recurrent translocations, such as conventional cytogenetics or fluorescence in situ hybridization, immunohistochemistry for a component of the fusion oncoprotein increasingly is being used as a surrogate marker, exploiting the tendency of these fusion components to be distinctively overexpressed by translocation-bearing tumor cells. Diagnostic immunohistochemistry can also be used to identify the characteristic gene expression changes that occur downstream of oncogenic fusions. Here, we review the use of immunohistochemistry to detect surrogate markers of recurrent translocations in soft tissue tumors, focusing on the practical applications and limitations of this diagnostic approach.

Climate effects on US infrastructure: the economics of adaptation for rail, roads, and coastal development.

Changes in temperature, precipitation, sea level, and coastal storms will likely increase the vulnerability of infrastructure across the USA. Using models that analyze vulnerability, impacts, and adaptation, this paper estimates impacts to railroad, roads, and coastal properties under three infrastructure management response scenarios: No Adaptation; Reactive Adaptation, and Proactive Adaptation. Comparing damages under each of these potential responses provides strong support for facilitating effective adaptation in these three sectors. Under a high greenhouse gas emissions scenario and without adaptation, overall costs are projected to range in the $100s of billions annually by the end of this century. The first (reactive) tier of adaptation action, however, reduces costs by a factor of 10, and the second (proactive) tier reduces total costs across all three sectors to the low $10s of billions annually. For the rail and road sectors, estimated costs for Reactive and Proactive Adaptation scenarios capture a broader share of potential impacts, including selected indirect costs to rail and road users, and so are consistently about a factor of 2 higher than prior estimates. The results highlight the importance of considering climate risks in infrastructure planning and management.

CD47 expression and CD163+ macrophages correlated with prognosis of pancreatic neuroendocrine tumor.

BACKGROUND: Recent studies have suggested the important roles of CD47 and tumor-associated macrophages in the prognosis and immunotherapy of various human malignancies. However, the clinical significance of CD47 expression and CD163+ TAMs in pancreatic neuroendocrine tumor (PanNET) remains unclear. METHODS: In this study, 47 well-differentiated PanNET resection specimens were collected. CD47 expression and CD163+ macrophages were evaluated using immunohistochemistry and correlated with clinicopathologic properties. RESULTS: Positive CD47 staining was seen in all PanNETs as well as adjacent normal islets. Compared to normal islets, CD47 overexpressed in PanNETs (p = 0.0015). In the cohort, lymph node metastasis (LNM), lymphovascular invasion (LVI), and perineural invasion (PNI) were found in 36.2, 59.6, and 48.9% of the cases, respectively. Interestingly, PanNETs with LNM, LVI, or PNI had significantly lower H-score of CD47 than those without LNM (p = 0.035), LVI (p = 0.0005), or PNI (p = 0.0035). PanNETs in patients with disease progression (recurrence/death) also showed a significantly lower expression of CD47 than those without progression (p = 0.022). In contrast, CD163+ macrophage counts were significantly higher in cases with LNM, LVI, and PNI. CONCLUSIONS: Our data suggest relative low CD47 expression and high CD163+ TAMs may act as indicators for poor prognosis of PanNETs.

Nuclear expression of DDIT3 distinguishes high-grade myxoid liposarcoma from other round cell sarcomas.

Myxoid liposarcoma (MLPS) is a malignant adipocytic neoplasm with predilection for the extremities. MLPS is genetically defined by a t(12;16) translocation leading to FUS-DDIT3 (95%) or more rarely t(12;22) leading to EWSR1-DDIT3. Low-grade MLPS is characterized by bland spindle cells within a myxoid matrix containing delicate "chicken-wire" vasculature, whereas high-grade ("round cell") MLPS may be indistinguishable from other round cell sarcomas. In many cases, cytogenetic or molecular genetic techniques are applied to confirm the diagnosis. A recent study documented the utility of DDIT3 immunohistochemistry (IHC) in the differential diagnosis of adipocytic and myxoid soft tissue tumors. The purpose of this study was to evaluate DDIT3 IHC as a surrogate for molecular testing in high-grade MLPS. IHC was performed using a mouse monoclonal antibody directed against the N-terminus of DDIT3 on whole tissue sections from 50 high-grade MLPS cases and 319 histologic mimics used as controls (170 on whole tissue sections and 149 on a tissue microarray). Histologic mimics included Ewing sarcoma, CIC-rearranged sarcoma, sarcomas with BCOR genetic alterations, poorly differentiated synovial sarcoma, alveolar and embryonal rhabdomyosarcomas, mesenchymal chondrosarcoma, desmoplastic small round cell tumor, and neuroblastoma. Nuclear staining in >5% of cells was considered positive. By IHC, 48 (96%) high-grade MLPS showed strong diffuse nuclear staining for DDIT3. Of the controls, 2% of cases were positive, with no more than 25% nuclear staining. An additional 19% of control cases displayed less than 5% nuclear staining. Overall, DDIT3 IHC showed 96% sensitivity and 98% specificity for high-grade MLPS; strong, diffuse staining is also 96% sensitive but is 100% specific. IHC using an antibody directed against the N-terminus of DDIT3 is highly sensitive and specific for high-grade MLPS among histologic mimics and could replace molecular genetic testing in many cases, although limited labeling may be seen in a range of other tumor types.

Analytical performance of lateral flow immunoassay for SARS-CoV-2 exposure screening on venous and capillary blood samples.

OBJECTIVES: We validate the use of a lateral flow immunoassay (LFI) intended for rapid screening and qualitative detection of anti-SARS-CoV-2 IgM and IgG in serum, plasma, and whole blood, and compare results with ELISA. We also seek to establish the value of LFI testing on blood obtained from a capillary blood sample. METHODS: Samples collected by venous blood draw and finger stick were obtained from patients with SARS-CoV-2 detected by RT-qPCR and control patients. Samples were tested with Biolidics 2019-nCoV IgG/IgM Detection Kit lateral flow immunoassay, and antibody calls were compared with ELISA. RESULTS: Biolidics LFI showed clinical sensitivity of 92% with venous blood at 7 days after PCR diagnosis of SARS-CoV-2. Test specificity was 92% for IgM and 100% for IgG. There was no significant difference in detecting IgM and IgG with Biolidics LFI and ELISA at D0 and D7 (p = 1.00), except for detection of IgM at D7 (p = 0.04). Capillary blood of SARS-CoV-2 patients showed 93% sensitivity for antibody detection. CONCLUSIONS: Clinical performance of Biolidics 2019-nCoV IgG/IgM Detection Kit is comparable to ELISA and was consistent across sample types. This provides an opportunity for decentralized rapid testing and may allow point-of-care and longitudinal self-testing for the presence of anti-SARS-CoV-2 antibodies.

Hypoxia theranostics of a human prostate cancer xenograft and the resulting effects on the tumor microenvironment.

Hypoxia is frequently observed in human prostate cancer, and is associated with chemoresistance, radioresistance, metastasis, and castrate-resistance. Our purpose in these studies was to perform hypoxia theranostics by combining in vivo hypoxia imaging and hypoxic cancer cell targeting in a human prostate cancer xenograft. This was achieved by engineering PC3 human prostate cancer cells to express luciferase as well as a prodrug enzyme, yeast cytosine deaminase, under control of hypoxic response elements (HREs). Cancer cells display an adaptive response to hypoxia through the activation of several genes mediated by the binding of hypoxia inducible factors (HIFs) to HRE in the promoter region of target gene that results in their increased transcription. HIFs promote key steps in tumorigenesis, including angiogenesis, metabolism, proliferation, metastasis, and differentiation. HRE-driven luciferase expression allowed us to detect hypoxia in vivo to time the administration of the nontoxic prodrug 5-fluorocytosine that was converted by yeast cytosine deaminase, expressed under HRE regulation, to the chemotherapy agent 5-fluorouracil to target hypoxic cells. Conversion of 5-fluorocytosine to 5-fluorouracil was detected in vivo by 19F magnetic resonance spectroscopy. Morphological and immunohistochemical staining and molecular analyses were performed to characterize tumor microenvironment changes in cancer-associated fibroblasts, cell viability, collagen 1 fiber patterns, and HIF-1α. These studies expand our understanding of the effects of eliminating hypoxic cancer cells on the tumor microenvironment and in reducing stromal cell populations such as cancer-associated fibroblasts.

Sequencing identifies multiple early introductions of SARS-CoV-2 to the New York City region.

Effective public response to a pandemic relies upon accurate measurement of the extent and dynamics of an outbreak. Viral genome sequencing has emerged as a powerful approach to link seemingly unrelated cases, and large-scale sequencing surveillance can inform on critical epidemiological parameters. Here, we report the analysis of 864 SARS-CoV-2 sequences from cases in the New York City metropolitan area during the COVID-19 outbreak in spring 2020. The majority of cases had no recent travel history or known exposure, and genetically linked cases were spread throughout the region. Comparison to global viral sequences showed that early transmission was most linked to cases from Europe. Our data are consistent with numerous seeds from multiple sources and a prolonged period of unrecognized community spreading. This work highlights the complementary role of genomic surveillance in addition to traditional epidemiological indicators.

WITHDRAWN: ASSOCIATION OF INITIAL VIRAL LOAD IN SARS-CoV-2 PATIENTS WITH OUTCOME AND SYMPTOMS.

The Publisher regrets that this article is an accidental duplication of an article that has already been published, https://doi.org/10.1016/j.ajpath.2020.07.001. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Association of Initial Viral Load in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Patients with Outcome and Symptoms.

The dynamics of viral load (VL) of the severe acute respiratory syndrome coronavirus 2 and its association with different clinical parameters remain poorly characterized in the US patient population. Herein, we investigate associations between VL and parameters, such as severity of symptoms, disposition (admission versus direct discharge), length of hospitalization, admission to the intensive care unit, length of oxygen support, and overall survival in 205 patients from a tertiary care center in New York City. VL was determined using quantitative PCR and log10 transformed for normalization. Associations were tested with univariate and multivariate regression models. Diagnostic VL was significantly lower in hospitalized patients than in patients not hospitalized (log10 VL = 3.3 versus 4.0; P = 0.018) after adjusting for age, sex, race, body mass index, and comorbidities. Higher VL was associated with shorter duration of the symptoms in all patients and hospitalized patients only and shorter hospital stay (coefficient = -2.02, -2.61, and -2.18; P < 0.001, P = 0.002, and P = 0.013, respectively). No significant association was noted between VL, admission to intensive care unit, length of oxygen support, and overall survival. Our findings suggest a higher shedding risk in less symptomatic patients, an important consideration for containment strategies. Furthermore, we identify a novel association between VL and history of cancer. Larger studies are warranted to validate our findings.

Sequencing identifies multiple early introductions of SARS-CoV-2 to the New York City Region.

Effective public response to a pandemic relies upon accurate measurement of the extent and dynamics of an outbreak. Viral genome sequencing has emerged as a powerful approach to link seemingly unrelated cases, and large-scale sequencing surveillance can inform on critical epidemiological parameters. Here, we report the analysis of 864 SARS-CoV-2 sequences from cases in the New York City metropolitan area during the COVID-19 outbreak in Spring 2020. The majority of cases had no recent travel history or known exposure, and genetically linked cases were spread throughout the region. Comparison to global viral sequences showed that early transmission was most linked to cases from Europe. Our data are consistent with numerous seeds from multiple sources and a prolonged period of unrecognized community spreading. This work highlights the complementary role of genomic surveillance in addition to traditional epidemiological indicators.

Health-related quality of life and balance confidence among participants in a senior community-based exercise (SWIFT) program compared to age matched controls: a cross-sectional study.

BACKGROUND: Staying Well, Independent and Fit Together (SWIFT), a seniors' exercise program, aims to promote health, strength, mobility and community engagement. We compared quality of life and balance confidence in SWIFT participants and non-participants, aged 60 years and older. METHODS: Cross-sectional study comparing participants and non-participants in SWIFT program using Older People's Quality of Life Questionnaire (OPQOL) and Activities-specific Balance Confidence Scale (ABCS). RESULTS: Seventy participants completed surveys, 41 in experimental and 29 in control group. We found a statistically significant between group difference favoring the control group in overall OPQOL score but not in OPQOL subscale nor overall ABCS scores. Participants in both groups participating in weekly exercises had non-significantly higher quality of life subscale scores. CONCLUSION: Results suggest seniors in both study groups who participate in exercise have non-significantly higher quality of life scores compared to those who do not participate in exercise. Participation in the SWIFT exercise program or activity in general, contributes to quality of life in seniors.

CONTEXTE: Staying Well, Independent and Fit Together (SWIFT) est un programme d'exercice physique pour personnes âgées visant à promouvoir la santé, la force, la mobilité et la participation aux activités de la collectivité. Nous avons comparé la qualité de vie et le degré de confiance de la personne dans son équilibre entre des sujets participant au programme SWIFT et des sujets n'y participant pas, tous ayant 60 ans et plus. MÉTHODOLOGIE: Étude transversale visant à comparer l'état de participants au programme SWIFT à celui de non-participants à l'aide de l'Older People's Quality of Life Questionnaire (OPQOL) et de l'échelle de mesure du degré de confiance de la personne dans son équilibre associé aux gestes de la vie quotidienne (échelle ABC-S). RÉSULTATS: Soixante-dix participants ont rempli les questionnaires, 41 dans le groupe expérimental et 29 dans le groupe témoin. On a observé une différence importante sur le plan statistique entre les groupes en faveur du groupe de contrôle pour ce qui est du score global au OPQOL, mais non pour le score de la souséchelle du OPQOL ni pour le score global de l'échelle ABC-S. Chez les sujets des deux groupes faisant les exercices hebdomadaires, on n'a pas observé de scores supérieurs significatifs de la sous-échelle de la qualité de vie. CONCLUSION: Les résultats semblent montrer que chez les sujets âgés des deux groupes suivant le programme d'exercices, les scores de qualité de vie ne sont pas plus élevés, d'une manière significative, que ceux des sujets ne suivant pas le programme. Le programme SWIFT, et de façon générale l'activité physique, contribue à la qualité de vie des personnes âgées.

Adult rhabdomyoma presenting as thyroid nodule on fine-needle aspiration in patient with Birt-Hogg-Dubé syndrome: Case report and literature review.

Extracardiac rhabdomyoma is an uncommon benign striated muscle tumor with a predilection for the head and neck region. However, it is extremely rare for extracardiac rhabdomyoma to present as a thyroid nodule. We report a case of rhabdomyoma diagnosed by thyroid fine-needle aspiration (FNA) in a patient with Birt-Hogg-Dubé (BHD) syndrome. A 60-year-old man with BHD syndrome presented for recurrent pneumothorax. Chest CT incidentally identified a thyroid nodule. Subsequent sonography confirmed a 4.44 × 2.28 × 2.82 cm solid, hypoechoic nodule with smooth margins in the right upper pole. Ultrasound-guided FNA revealed many clusters and scattered isolated large polygonal cells with abundant granular cytoplasm and small peripherally located nuclei. Vague striations in the cytoplasm were focally identified. No follicular cells or colloid was present. Immunocytochemistry on one direct smear slide demonstrated diffuse positivity for desmin, supporting muscular differentiation. Subsequent surgery identified an adult rhabdomyoma originating from the inferior constrictor muscle of the neck and anteriorly displacing the thyroid. Because the mass was intimately associated with the thyroid gland, it was initially mistaken for a thyroid nodule on ultrasound. Diagnosis of rhabdomyoma on FNA is challenging, especially when rhabdomyoma mimics a thyroid nodule on imaging. The differential diagnosis includes Hurthle cell neoplasm, granular cell tumor, colloid nodule, and normal striated skeletal muscle. Adequate radiologic data and familiarity with the cytologic features of rhabdomyoma are critical for an accurate diagnosis.

Concurrent Identification of Novel EGFR-SEPT14 Fusion and ETV6-RET Fusion in Secretory Carcinoma of the Salivary Gland.

Salivary gland secretory carcinoma, also termed mammary analogue secretory carcinoma (MASC), is a recently described salivary gland neoplasm with characteristic histomorphologic findings similar to those of secretory carcinoma of the breast and harboring recurrent ETV6-NTRK3 fusions. Recent findings have expanded the molecular profile of salivary gland secretory carcinoma to include multiple novel ETV6 fusion partners, including RET, MET, and MAML3. Here, we report a case of cystic MASC with cribriform and papillary histology harboring two gene fusions, ETV6-RET and EGFR-SEPT14, identified by targeted RNA sequencing. The presence of the rearrangements was confirmed by FISH, RT-PCR, and Sanger sequencing. This is the first EGFR-SEPT14 fusion reported in secretory carcinoma as a single event or in association with an ETV6 rearrangement. This finding adds to the expanding molecular profile of this tumor entity, and may translate into novel treatment strategies.

A limb to stand on? A scoping review of employability assessment in Australian total and permanent disability insurance claims.

Purpose: Employability assessment helps in deciding to pay or decline Australian total and permanent disability insurance claims, yet it has not been critically examined. This paper reviews employability assessment from forensic vocational assessment, life insurance/superannuation, and legal perspectives.Methods: In a scoping review, we searched six multidisciplinary databases and various industry-specific resources. Items pertinent to forensic employability/vocational assessment and life insurance total and permanent disability claims were included. Return-to-work assessment, the vocational assessor, medical or functional evaluation, and case law items were excluded. Quality appraisal measures were used for research studies and other items. From 104 full-text reviews, 39 items were included for thematic synthesis from the three perspectives of interest.Results: Our review found that employability assessment is derived from forensic vocational assessment, but methodology differs in claimant contact and psychosocial aspects. Employability assessment practice is informed by policy, market changes, and legal interpretation. Assessors may work for opposing sides in forensic or indirect settings therefore high standards and credentials must prevail.Conclusions: Foundational research into the effectiveness of employability assessment and the experience of claimants is warranted. Future research into methodology, assessor credentials, and legal aspects will broaden understanding of this relatively new topic.Implications for rehabilitationEmployability assessment is an emergent and hitherto unexamined model that operates in the multi-billion-dollar Australian total and permanent disability insurance market.Total and permanent disability insurance policies and their legal interpretation are ever-changing and substantially inform employability assessment practice.Employability assessment lacks methodology and variables that are common elements in proven forensic vocational assessment models in the United States.Training and credentialing of rehabilitation professionals who conduct employability assessments are required to withstand legal scrutiny and meet international forensic standards.

Issues facing employability assessment in total and permanent disability insurance claims: A rehabilitation perspective.

BACKGROUND: Expert employment information helps life insurers to decide total and permanent disability claims. The employability assessment model was developed a decade ago by rehabilitation counselors and has not been critically examined. OBJECTIVE: This exploratory descriptive study aims to elicit key issues of employability assessment within Australian life insurance. METHODS: Ten rehabilitation advisors with knowledge of employability assessment in the total and permanent disability sector participated in a single focus group. They each nominated issues of concern about employability assessment. These issues were collated then discussed within the group. Qualitative thematic analysis was used to identify key issues. RESULTS: The predominant theme was the forensic nature of employment evidence. There were three categories of key issues. First, assessment providers- their training, qualifications, experience, and role. Second, methodology- approaches that provide most realistic information about a claimant's likelihood of work. Third, policy definitions that illustrate reliance on legal interpretation of employability. CONCLUSIONS: To withstand legal scrutiny, the credentials of providers, assessment methodology, and quality of forensic reports are key issues which need to be addressed. This foundational study will contribute to broader research on this topic, with implications particularly for rehabilitation, life insurance, and claimants.

Are we crying Wolff? 3D printed replicas of trabecular bone structure demonstrate higher stiffness and strength during off-axis loading.

Roux's principle of bone functional adaptation postulates that bone tissue, and particularly trabecular bone tissue, responds to mechanical stimuli by adjusting (modeling) its architecture accordingly. Hence, it predicts that the new modeled trabecular structure is mechanically improved (stiffer and stronger) in line with the habitual in vivo loading direction. While previous studies found indirect evidence to support this theory, direct support was so far unattainable. This is attributed to the fact that each trabecular bone is unique, and that trabecular bone tissue tends to be damaged during mechanical testing. Consequently, a unique modeled trabecular structure can be mechanically tested only along one direction and a comparison to other directions for that specific structure is impossible. To address this issue, we have 3D printed 10 replicas of a trabecular structure from a sheep talus cropped along the 3 principal axes of the bone and in line with the principal direction of loading (denoted on-axis model). Next, we have rotated the same cropped trabecular structure in increments of 10° up to 90° to the bone principal direction of loading (denoted off-axis models) and printed 10 replicas of each off-axis model. Finally, all on-axis and off-axis 3D printed replicas were loaded in compression until failure and trabecular structure stiffness and strength were calculated. Contrary to our prediction, and conflicting with Roux's principle of bone functional adaptation, we found that a trabecular structure loaded off-axis tended to have higher stiffness and strength values when compared to the same trabecular structure loaded on-axis. These unexpected results may not disprove Roux's principle of bone functional adaptation, but they do imply that trabecular bone adaptation may serve additional purposes than simply optimizing bone structure to one principal loading scenario and this suggests that we still don't fully understand bone modeling in its entirety.