TP Trajectory Technique for Thoracic Pedicle Screw Placement Improving Accuracy and Reproducibility
Baron S. Lonner, MD and Yuan Ren, MS, PhD
Accessing the pedicle of the spine for fixation in spinal deformity surgery is challenging. Drs. Baron Lonner and Yuan Ren have developed a new technique, the Transverse Process Trajectory Technique, to be tested and compared to the traditional free-hand technique. CT scan evaluation, axial pullout, and torsional testing will be performed in this cadaver study.
A number of techniques, including free-hand (FH) and the in-out-in techniques, have been utilized for pedicular fixation and correction of scoliosis. Placement of thoracic pedicle screws is confounded by spinal deformity and a learning curve. Dr. Lonner introduced the innovative Transverse Process Trajectory (TPT) technique that takes advantage of the patient’s innate anatomy serving as a conduit into the pedicle. The approach also has the potential to improve torsional loading properties for derotation techniques due to its very lateral starting point away from the axis of rotation. The technique utilizes a starting point at the lateral aspect of the superior facet and its junction with the cephalad 1/3 of the transverse process (TP). The TP is drilled to its ventral cortex along its entire length from the tip. This provides a corridor for a 2mm power drill that follows the TP trajectory (Figure 1).
Three surgeons of varying experience level (1. experienced with 20yrs of practice, 2. surgeon with <10yrs of experience and 3. resident trainee) will perform TPT alternating with the FH technique on 2 cadavers each. Time for screw placement will be assessed. CT scan and visual inspection will be performed to assess accuracy of screw placement for the two techniques specifically observing for critical breaches that might result in neurological injury. Screw pull-out strength and torsional loading will also be compared. Learning curve assessment will be performed between surgeons and techniques by comparing the above between the three surgeons.
Figure: Illustration of the in-out-in, free-hand (FH) and Transverse Process Trajectory (TPT) techniques.
Baron S. Lonner, MD
Chief, Division of Spine Surgery
Mount Sinai Beth Israel
Professor of Orthopaedic Surgery
Director, Scoliosis and Spine Associates
Yuan Ren, MS, PhD
Department of Orthopaedic Surgery
Mount Sinai Beth Israel
Development of a Computational “Worst Case” Device Performance Tool for Use in
Evaluating Orthopaedic Implant Device Design Envelopes: ACL Graft Pilot
Edward Nyman, Jr., PhD and Anil K. Gupta, MD, MBA
Our goal is fusion of realistic human activity and finite element modeling to drive surrogate computational models that improve the “handoff” from industry to regulatory bodies via a desktop tool for enhanced evaluation of the intersection between device design and in-vivo use.
ECORE exists to improve the orthopaedic medical device scientific and clinical paradigm through the fusion of cutting-edge bioengineering and orthopaedic surgery approaches. Currently, the orthopaedic research literature reports increased use of hip, knee, and spine devices in ever more demanding applications as well as use of new material combinations. It is well known that pre-market regulatory body required testing must address safety for evolving new, high-demand indications. Patient safety rests heavily on pre-market testing based on performance in worst-case conditions. Recall that metal-on-metal hip implants, for instance, performed very well in bench tests but failed at very high rates in patients in part because such tests did not successfully create worst-case in-vivo conditions. This project will facilitate more accurate prediction of critical-to-quality worst-case testing scenarios for synthetic ACL graft devices. Probabilistic simulations will create a repository of potential worst-case configurations that can be matched to device specifications and physically tested. Its availability to reviewers will promote consistency in review of novel devices and encourage manufacturers to bring devices to fruition.
Edward Nyman, Jr., PhD
University of Findlay
Anil K. Gupta, MD, MBA
Sports Medicine, Shoulder Surgery, Hip Arthroscopy
Engineering Center for Orthopaedic Research Excellence (ECORE)
University of Toledo
Patient-Specific Engineered Cartilage Surfaces for Knee Repair
Grace O'Connell, PhD and Galateia Kazakia, PhD
Total joint replacement has been successful in reducing pain and improving joint function for patients with debilitating osteoarthritis. However, these procedures are limited to older patients (>50 years) and have a limited lifespan. Effective treatment of injured or localized osteoarthritic cartilage may prevent further damage and reduce the need for total joint replacement. An alternative approach is to develop engineered tissues in the laboratory for implantation. In the last decade, regenerative medicine has advanced towards personalized biological treatment strategies for musculoskeletal diseases, including clinical trials for engineered cartilage repair (e.g. NeoCart and CARTIPATCH). Translating tissue-engineering techniques towards developing large clinically relevant implants has been challenging due to nutrient diffusion issues, resulting in reduced tissue growth in larger engineered tissues. Recently, Dr. Grace O’Connell, developed a technique for cultivating larger engineered cartilage surfaces using fractal fabrication where smaller engineered cartilage plugs are cultured together to form attachments and create larger surfaces. In collaboration with Dr. Galateia Kazakia, high-resolution computed tomography images are acquired from human tibias to develop culture molds with patient-specific anatomic contours. Developing engineered cartilage with patient-specific anatomic curvature is crucial for minimizing contact stresses and for maintaining continuous stress distribution during physiological loading.
Figure 1: Engineered cartilage surfaces in 3D printed molds (top). Surfaces can be cultivated to specified dimensions (bottom left) with tissue growing between constructs to form secure attachments (bottom right).
Grace O’Connell, PhD
U.C. San Francisco
Radiology and Biomedical Imaging
Figure 2: 3D high resolution CT scan of a tibia plateau used to create a surface contour that can be used to create 3D printed mold for culturing engineered cartilage surfaces with patient specific anatomy (bottom right).
Picodroplet Printing for High Throughput Biology
Zev Gartner, PhD, Adam Abate, PhD and Russell Cole, PhD
Biology is becoming an increasingly quantitative science, aided by the advent of new "big data" technologies like mass-spec and next gen sequencing. However, a bottleneck in the biological research pipeline is methods for equally high throughput experimentation. Drs. Zev Gartner, Adam Abate, and Russell Cole are developing a new paradigm in biological experimentation that seeks to miniaturize conventional well-plate fluid handling from the microliter to the picoliter scale. Using microfluidics, automation, and bioinformatics the team addresses two key bottlenecks in high throughput biological experimentation. Firstly, by miniaturizing the reactors, they can perform ~100,000 isolated, individual reaction on the same footprint as a 96 well plate. Moreover, by shrinking to the level of picoliters, they are able to isolate and analyze single cells using a wide range of modalities, including non-destructive modalities like brightfield and fluorescence imaging and destructive modalities like mass spectrometry and nextgen sequencing. They anticipate applications of their technology throughout the biological sciences, from single cell sequencing and chemical library screening, to synthetic biology and tissue printing.
U.C. San Francisco
U.C. San Francisco
Russell Cole, PhD
U.C. San Francisco
Figure 1: An array of picoliter droplets dispensed to a surface for use as individual reaction containers.
Figure 2: A microtissue recapitulated using estrogen receptor positive and estrogen receptor negative cells.