Investigation of shape memory effect in Ni-Ti based alloys

Shape memory alloys (SMAs) are ones which can return to their original shape under impact of temperature or external magnetic field. The SMAs are capable of many applications in the fields of biomedical, aerospace, microelectronics, automation, for examples, orthodontics, stents, bone anchors, automatic valves, heat sensors, nanotweezers, robots... Recently, researchers have discovered the shape memory effect (SME) on high entropy alloys (HEAs). The combination of superior properties of SMAs and HEAs (high strength, heat resistance, low diffusion coefficient...) would bring useful practical applications in practice. In this paper, we will present an overview of the research situation of SMAs and our initial results obtained on Ni-Ti based alloys of Ni-Ti, Ni-Ti-Zr-Cu-Cr, Ni-Ti-Zr-Cu-Co, Ni-Ti-Zr-Cu-Nb, and Ni-Ti-Zr-Cu-Hf prepared by melt-spinning method.

A Comparative Study of Automatic Localization Algorithms for Spherical Markers within 3D MRI Data

Localization of features and structures in images is an important task in medical image-processing. Characteristic structures and features are used in diagnostics and surgery planning for spatial adjustments of the volumetric data, including image registration or localization of bone-anchors and fiducials. Since this task is highly recurrent, a fast, reliable and automated approach without human interaction and parameter adjustment is of high interest. In this paper we propose and compare four image processing pipelines, including algorithms for automatic detection and localization of spherical features within 3D MRI data. We developed a convolution based method as well as algorithms based on connected-components labeling and analysis and the circular Hough-transform. A blob detection related approach, analyzing the Hessian determinant, was examined. Furthermore, we introduce a novel spherical MRI-marker design. In combination with the proposed algorithms and pipelines, this allows the detection and spatial localization, including the direction, of fiducials and bone-anchors.

Biomechanical Characteristics of Labral Augmentation Versus Labral Reconstruction in a Hip Cadaver Model

Objectives: An integral component of hip stability is the negative pressure gradient created by the labral suction seal. No prior studies have quantitatively compared the integrity of the suction seal under normal, pathologic, and surgical conditions. The purpose of this study was to evaluate the biomechanical properties of the labral suction seal in the following four scenarios: intact labrum, labral tear, labral augmentation, and labral reconstruction. Methods: Eight fresh-frozen hemi-pelvises without osteoarthritis and with an intact labrum were dissected to the level of labrum and mounted for biomechanical testing. Each specimen was evaluated sequentially under four testing conditions: intact labrum, labral tear, labral augmentation, and labral reconstruction. Following testing of the intact labrum, the specimens were manipulated to create a labral tear from 12- to 3-o’clock. Labral augmentation was then performed with bone anchors and iliotibial band graft after debridement of only the peripheral half of the labral tear. Labral reconstruction was performed last with bone anchors and iliotibial band graft after removing the entire labral tear. In each condition the specimens were placed in the test machine to undergo pure distraction of the joint. First, the femur was compressed with 250 N of force and then distracted at 10 mm/s with force and displacement continuously recorded until the suction seal was disrupted. In each specimen, the tests were repeated for a total of three tests in each of the four conditions, and the average peak force was calculated. Data was normalized to the intact peak force for each specimen to account for gender and size differences. Statistical testing was performed via a repeated measures ANOVA with a post hoc Bonferroni correction for pairwise analysis. Results: Peak loads occurred early in displacement. The average peak force values (mean ± standard deviation) were as follows: intact (137.2 ± 40.7), labral tear (126.3 ± 43.5), labral augmentation (94.7 ± 59.7), labral reconstruction (78.9 ± 51.2). The average normalized peak force values relative to the intact condition were as follows: labral tear (91.1 ± 8.5), augmentation (66.1 ± 27.6), and reconstruction (55.6 ± 25.7). There was no statistically significant difference in peak force relative to the intact labrum for the labral tear (p = 0.34). Relative to the labral tear, there was no significant difference in peak force for the augmentation (p = 0.12), but there was a significant decrease in peak force for the reconstruction (p = 0.03). Conclusion: This model provides a new means of quantitatively evaluating the labral suction seal under various normal, pathologic, and surgical conditions. The results show that relative to the labral tear condition, labral augmentation may recreate the labral suction seal better than labral reconstruction. Clinically, these findings suggest augmentation may improve hip stability over labral reconstruction. [Figure: see text]

Surgical repair of an osseous avulsion of the adductor sleeve complex of the groin: a case report

Sports-related groin injuries are common among athletes. Avulsion of the tendons attached to the symphysis pubis has previously been described. These can be managed both operatively and non-operatively. To our knowledge a complete osseous avulsion of the adductor sleeve has not been described previously. We report a case of a 56-year-old healthy man who sustained an acute osseous avulsion of the adductor sleeve complex on the left side, which was surgically repaired with bone anchors and a mesh. Return to normal activity was reached 8 weeks after immobilization and full return to play for all sports activities in 12 weeks.