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The purpose of this study was to determine the influence of frontal and transverse plane rotations of the femur and tibia on peak maximum principal stress in the patellar tendon. Using finite element modeling, patellar tendon stress profiles of eight healthy individuals were obtained during a simulated squatting task (45° of knee flexion). The femur and tibia of each model were rotated 10° (in 2° increments) along their respective axes beyond that of the natural degree of rotation. This process was repeated for the transverse plane (internal and external rotation) and frontal plane (adduction and abduction). Quasi‐static loading simulations were performed to quantify peak maximum principal stress in patellar tendon. Internal and external rotations of the femur and tibia that exceeded 4° beyond that of the natural rotation resulted in progressively greater patellar tendon stress (p < 0.05). Incremental femur and tibia adduction and abduction resulted in an increase in patellar tendon stress, but only at the end range of motions evaluated. These results suggest that tibiofemoral rotations in the frontal and transverse planes have the potential to influence patellar tendon stress. In particular, patellar tendon stress is highly sensitive to small degrees of tibia and/or femur motions in the transverse plane. [ABSTRACT FROM AUTHOR]

Background: Osteoporosis is a progressive bone disease that is characterized by a decrease in bone mass and the deterioration in bone microarchitecture, which might be related to age and space travel. An unmet need exists for the development of novel imaging technologies to characterize osteoporosis. Purpose: The purpose of our study is to investigate the feasibility of X‐ray‐induced acoustic computed tomography (XACT) imaging for osteoporosis detection. Methods: An in‐house simulation workflow was developed to assess the ability of XACT for osteoporosis detection. To evaluate this simulation workflow, a three‐dimensional digital bone phantom for XACT imaging was created by a series of two‐dimensional micro‐computed tomography (micro‐CT) slices of normal and osteoporotic bones in mice. In XACT imaging, the initial acoustic pressure rise caused by the X‐ray induce acoustic (XA) effect is proportional to bone density. First, region growing was deployed for image segmentation of different materials inside the bone. Then k‐wave simulations were deployed to model XA wave propagation, attenuation, and detection. Finally, the time‐varying pressure signals detected at each transducer location were used to reconstruct the XACT image with a time‐reversal reconstruction algorithm. Results: Through the simulated XACT images, cortical porosity has been calculated, and XA signal spectra slopes have been analyzed for the detection of osteoporosis. The results have demonstrated that osteoporotic bones have lower bone mineral density and higher spectra slopes. These findings from XACT images were in good agreement with porosity calculation from micro‐CT images. Conclusion: This work explores the feasibility of using XACT imaging as a new imaging tool for Osteoporosis detection. Considering that acoustic signals are generated by X‐ray absorption, XACT imaging can be combined with traditional X‐ray imaging that holds potential for clinical management of osteoporosis and other bone diseases. [ABSTRACT FROM AUTHOR]

ABSTRACT The landscape of basic science in the United States and around the world is changing, and the field of orthopaedic research is positioned to lead by embracing a culture of collaborative, team science that reflects our field's interdisciplinary nature. In this article we hope to address some of the cultural challenges and programmatic barriers that impede a team science approach in the US and suggest opportunities for change. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1673-1679, 2016. [ABSTRACT FROM AUTHOR]

Purpose: To develop a method for measuring bone mineral density (BMD) with MRI, and to validate this method against quantitative computed tomography (QCT). Materials and Methods: A mathematical relationship between signal intensities from proton-density-weighted in-phase images generated by multi-fat-peak T [ABSTRACT FROM AUTHOR]

Proximal femoral metastases can lead to pathologic fracture. The goals of this study were to improve guidelines for assessing pathologic hip fracture risk by quantifying the effect of location of femoral neck metastases on hip strength under single-limb stance loading and to evaluate the effectiveness of a proposed minimally invasive surgical repair technique for restoring hip strength. Twelve matched pairs of human cadaveric proximal femora were used to create a total of 564 finite element models before and after introduction and repair of simulated lytic defects, modeled as spherical voids, at various locations within the femoral neck. Defect site greatly affected hip strength ( p < 0.001). Defects in the inferomedial aspect of the neck and in the dense trabecular bone near the base of the femoral head had the greatest effect, with hip strengths 23% to 72% and 43% to 64% that of the intact strength, respectively, for 20-mm diameter defects. Even so, the proposed percutaneous repair technique restored static strength of femora with defects at all of the studied locations. These findings may lead to a reduction in the number of patients who suffer a preventable pathologic fracture, a decreased likelihood of unnecessary surgery, and a less invasive prophylactic surgical procedure. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1127-1132, 2008 [ABSTRACT FROM AUTHOR]