Vision-based pose estimation of craniocervical region: experimental setup and saw bone-based study

Summary This article discusses the intervertebral motion present in the craniovertebral junction (CVJ) region. The CVJ region is bounded by the first three vertebras from the spinal column. It helps in bringing most of the neck motion. Intervention in this region requires surgery in which an implant is placed to stabilize the whole system. The various available implants need to undergo performance evaluation as their performance varies from region and anatomical diversity. For the Indian population, we are targeting to evaluate the performance of such an implant, testing it into a cadaver. The region of interest will be loaded as per the loading condition of an average human. Motion in these regions is evaluated using the camera. A preliminary test was done on a saw bone model of CVJ to assess the performance of segmentation methods. Multiple such ArUco markers are used to increase pose accuracy further, and the pose of the entire board of multiple tags provides us with reliable pose estimation. The absolute error ranged from a minimum of 0.1 mm to a maximum of 16 mm. At the same time, the mean and median absolute errors were 3.8961 mm and 3.35 mm. By considering the absolute lengths, the percentage error showed the following trends. The percentage error was between 3.9168% and 0.0230%.

Standardized artificially created stable pertrochanteric femur fractures present more homogenous results compared to osteotomies for orthopaedic implant testing

Background With regard to biomechanical testing of orthopaedic implants, there is no consensus on whether artificial creation of standardized bone fractures or their simulation by means of osteotomies result in more realistic outcomes. Therefore, the aim of this study was to artificially create and analyze in an appropriate setting the biomechanical behavior of standardized stable pertrochanteric fractures versus their simulation via osteotomizing. Methods Eight pairs of fresh-frozen human cadaveric femora aged 72.7 ± 14.9 years (range 48–89 years) were assigned in paired fashion to two study groups. In Group 1, stable pertrochanteric fractures AO/OTA 31-A1 were artificially created via constant force application on the anterior cortex of the femur through a blunt guillotine blade. The same fracture type was simulated in Group 2 by means of osteotomies. All femora were implanted with a dynamic hip screw and biomechanically tested in 20° adduction under progressively increasing physiologic cyclic axial loading at 2 Hz, starting at 500 N and increasing at a rate of 0.1 N/cycle. Femoral head fragment movements with respect to the shaft were monitored by means of optical motion tracking. Results Cycles/failure load at 15° varus deformation, 10 mm leg shortening and 15° femoral head rotation around neck axis were 11324 ± 848/1632.4 ± 584.8 N, 11052 ± 1573/1605.2 ± 657.3 N and 11849 ± 1120/1684.9 ± 612.0 N in Group 1, and 10971 ± 2019/1597.1 ± 701.9 N, 10681 ± 1868/1568.1 ± 686.8 N and 10017 ± 4081/1501.7 ± 908.1 N in Group 2, respectively, with no significant differences between the two groups, p ≥ 0.233. Conclusion From a biomechanical perspective, by resulting in more consistent outcomes under dynamic loading, standardized artificial stable pertrochanteric femur fracture creation may be more suitable for orthopaedic implant testing compared to osteotomizing the bone.

Audiology Telemedicine Evaluations: Potential Expanded Applications

There is underutilization of cochlear implants with delays in implantation linked to distance from implant centers. Telemedicine could connect cochlear implant specialists with patients in rural locations. We piloted telemedicine cochlear implant testing in a small study, largely composed of normal-hearing volunteers to trial this new application of teleaudiology technology. Thirteen subjects (8 with normal hearing and 5 with hearing loss ranging from mild to profound) underwent a traditional cochlear implant evaluation in person and then via telemedicine technology. Routine audiometry, word recognition testing, and Arizona Biological Test (AzBio) and consonant-nucleus-consonant (CNC) testing were performed. Mean (SD) percent difference in AzBio between in-person and remote testing was 1.7% (2.06%). Pure tone average (PTA), speech reception threshold (SRT), and word recognition were similar between methods. CNC testing showed a mean (SD) difference of 6.8% (10.2%) between methods. Testing conditions were acceptable to audiologists and subjects. Further study to validate this method in cochlear implant candidates and a larger population is warranted.

Experimental Study of Bio-Polymer Knee Implant

This study tests a custom-designed knee implant made of an FDA approved biomaterial, Chronoflex AR. The implant is designed to cushion the damaged cartilage at the distal end of the femur to reduce knee pain without the removal of cartilage and bone. A patient’s MRI scan was used to render a 3D computer graphic design of the knee. The manufacturing of the implant is conducted by 3D printing the shape of the distal end of the femur and coating it with the biomaterial. This is a preliminary fabrication method. Ultimately, the implant material will be 3D printed or cast in 3D printed molds. A successful implementation of this sort of custom-designed implant would reduce the invasiveness of knee correcting procedures, enable the patient to retain the shape of his or her femoral and tibial anatomy, and reduce the possibility of revision surgeries. A custom knee implant testing machine was designed and fabricated to measure the force, elastic deformation, plastic deformation, wear and fatigue of the component after performing lab tests simulating a normal walking pattern while adhering to ISO standards.