Signing data citations enables data verification and citation persistence.

Commonly used data citation practices rely on unverifiable retrieval methods which are susceptible to content drift, which occurs when the data associated with an identifier have been allowed to change. Based on our earlier work on reliable dataset identifiers, we propose signed citations, i.e., customary data citations extended to also include a standards-based, verifiable, unique, and fixed-length digital content signature. We show that content signatures enable independent verification of the cited content and can improve the persistence of the citation. Because content signatures are location- and storage-medium-agnostic, cited data can be copied to new locations to ensure their persistence across current and future storage media and data networks. As a result, content signatures can be leveraged to help scalably store, locate, access, and independently verify content across new and existing data infrastructures. Content signatures can also be embedded inside content to create robust, distributed knowledge graphs that can be cited using a single signed citation. We describe applications of signed citations to solve real-world data collection, identification, and citation challenges.

Safe Parameters for Utilizing Magnetic Growth Rods in Patient With a Vagal Nerve Stimulator and Case Report.

BACKGROUND: Magnetic growing rods are being utilized more frequently in children with early-onset scoliosis. Many of these children have multiple medical problems and additional medical devices implanted that utilize similar magnetic technology, including vagal nerve stimulator (VNS) devices. There is some concern that the external remote controller (ERC) used to control the magnetic growth rod will interact with these devices during lengthening procedures. We believe there are safe parameters which allow the magnetic growth rod ERC to be utilized in patients with an implanted VNS. METHODS: A VNS device was tested in a simulation with the magnetic growth rods ERC to determine if it would activate/inactivate the device during a lengthening procedure. This study consists of 2 simulations. Simulation 1 evaluates placing the VNS adjacent to the ERC in the same coronal plane. Simulation 2 elevates the ERC placement above the device to simulate the thickness of a torso while increasing the distance of the VNS from the ERC in the coronal plane. RESULTS: The time of exposure of the VNS device to the magnetic field had no correlation with activation. Distance had an effect on device activation. In the coronal plane of the device, activation occurred 43% of the time at 0 cm, 71% at 4 cm, and 5% activation at 8 cm. Greater than 10 cm had no activation. In the sagittal plane with the ERC 8 cm above the device, activation occurred 71% at 0 cm distance, 38% at 2 cm, and no activation occurred at a distance of >4 cm. CONCLUSIONS: Utilization of the magnetic growth rod ERC can be carried out safely in patients with a VNS. Simulations show that an actuator implanted 4 cm from the VNS device in the coronal plane in a child with >8 cm chest wall thickness will not activate the VNS device. When choosing a rod configuration for implantation, the child's chest wall thickness and the ERC placement should be considered.

CT provides precise size assessment of implanted titanium alloy pedicle screws.

BACKGROUND: After performing instrumented spinal fusion with pedicle screws, postoperative imaging using CT to assess screw position may be necessary. Stainless steel implants produce significant metal artifact on CT, and the degree of distortion is at least partially dependent on the cross-sectional area of the implanted device. If the same effect occurs with titanium alloy implants, ability to precisely measure proximity of screws to adjacent structures may be adversely affected as screw size increases. QUESTIONS/PURPOSES: We therefore asked whether (1) CT provides precise measurements of true screw widths; and (2) precision degrades based on the size of the titanium implant imaged. METHODS: CT scans performed on 20 patients after instrumented spinal fusion for scoliosis were reviewed. The sizes of 151 titanium alloy pedicle screws were measured and compared with known screw size. The amount of metal bloom artifact was determined for each of the four screw sizes. ANOVA with Tukey's post hoc test were performed to evaluate differences in scatter, and Spearman's rho coefficient was used to measure relationship between screw size and scatter. RESULTS: All screws measured larger than their known size, but even with larger 7-mm screws the size differential was less than 1 mm. The four different screw sizes produced scatter amounts that were different from each other (p < 0.001).The amount of metal bloom artifact produced does increase as the size of the screw increases (rho = 0.962, p < 0.001). CONCLUSIONS: CT of titanium alloy pedicle screws produces minimal artifact, thus making this the preferred imaging modality to assess screw position after surgery. Although the amount of artifact increases with the volume of titanium present, the degree of distortion is minimal and is usually less than 1 mm.

Diagnostic knee arthroscopy: a pilot study to evaluate surgical skills.

PURPOSE: To develop a scoring system to evaluate individual proficiency at diagnostic knee arthroscopy. METHODS: This was a prospective blinded study. Subjects included residents in postgraduate year (PGY) 1 through PGY 5 (n = 20) and staff surgeons (n = 10). All subjects performed a diagnostic arthroscopy on a cadaveric knee. Subjects were evaluated on both completeness and time required to complete the arthroscopy. The examiner viewed the arthroscopy from a remote location and was blinded to the level of training of the subjects. During the arthroscopy, 15 areas required assessment to achieve a score of 75 points. An additional 25 points were awarded depending on the time it took to complete the arthroscopy. A maximum of 100 points were available (Total score = Arthroscopy score + Time score). RESULTS: Thirty subjects were divided into 3 groups: group 1 (PGY 1 or 2) (n = 12), group 2 (PGY 3, 4, or 5) (n = 8), and group 3 (staff) (n = 10). In group 1 the mean total score was 28.25 points, the mean time to complete arthroscopy was 11.9 minutes, and the mean number of structures not examined was 8.67. In group 2 the mean total score was 76 points, the mean time to complete arthroscopy was 8.2 minutes, and the mean number of structures not examined was 1.75. In group 3 the mean total score was 100 points, the mean time to complete arthroscopy was 4.6 minutes, and the mean number of structures not examined was 0. Statistically significant differences by use of an analysis of variance test were noted for the total score, total time, and number of missed structures (P < .001). CONCLUSIONS: Using our skills assessment tool, we were able to evaluate subjects and determine their relative technical skill level in performing a diagnostic arthroscopy. This tool was able to distinguish among the novice, experienced, and expert levels in performing diagnostic arthroscopy. LEVEL OF EVIDENCE: Level III, development of diagnostic criteria on the basis of consecutive subjects.

Peripheral versus aperture fixation for anterior cruciate ligament reconstruction.

Because both the young and aging population are showing increasing interest in sports participation, the number of sports related injuries and in particular anterior cruciate ligament (ACL) injuries have been increasing. Because of these injuries much time and energy has been focused on ACL reconstruction in order to return these individuals to their optimal level of participation in their sport. This article explores and reviews the concepts of ACL fixation location and how this affects the ultimate outcome of this reconstructive procedure.

Thoracic pedicle screw placement: analysis using anatomical landmarks without image guidance.

STUDY DESIGN: Prospective laboratory study analyzing the technique of pedicle screw placement in a cadaveric model. OBJECTIVES: To determine whether a freehand technique without image guidance can be used to safely place pedicle screws in the thoracic spine. SUMMARY OF BACKGROUND DATA: The use of thoracic pedicle screws for the treatment of spinal deformity has been gaining increased acceptance among surgeons. Although these implants improve deformity correction, there is still concern regarding the risks to neurological and vascular structures and regarding the experience level needed to use this implant. This study was designed to determine whether these implants could be placed safely without imaging modalities. METHODS: Six fresh cadaveric specimens were instrumented from vertebral segments T4-T11. Ninety-six screws were placed along the anatomical axis of the pedicle. Pedicles were dissected to determine the wall violations, the position of neural structures, and the lateral coverage of the pedicle by the rib head. RESULTS: Ninety-seven percent of screws had less than 1 mm of wall violation, with 84 screws (87.5%) fully contained within the pedicle. Four screws (4.16%) violated the medial cortex. No violations occurred superiorly, inferiorly, or anteriorly. Nerve roots were in contact with the inferior pedicle wall at all levels. The average distance from nerve to the superior pedicle ranged from 3.85 to 5.04 mm. CONCLUSIONS: Placing pedicle screws along the anatomical axis without image guidance produced a low level of pedicle wall disruption. This technique uses a reproducible start point at each level, and the results are equal to or better than those of other cadaveric studies that have used guidance systems.

Olecranon fracture fixation utilizing a bioabsorbable tension band construct: analysis of stability with motion in a cadaveric model.

This study was performed to determine if tension band suturing with bioabsorbable materials can maintain fracture (osteotomy) reduction when subjected to an early motion protocol. Olecranon osteotomies were created in 13 cadaveric upper extremities and then sequentially fixed with axial Kirschner wires, and tension band wiring/suturing utilizing: musical #1 PDS (Ethicon Inc., Somerville, New Jersey, USA), musical #1 Panacryl (Ethicon Inc.), musical #2 Panacryl (Ethicon Inc.), and 18 gauge surgical wire. Specimens were cycled through a range of motion in a continuous passive motion machine. Specimens fixed with K-wires only, musical #1PDS and musical #1 Panacryl tension band suturing failed to maintain osteotomy reduction. Only surgical steel and musical #2 Panacryl maintained osteotomy reduction; both were superior to the other fixation methods (P<0.001). The musical #2 Panacryl suture is an excellent choice for a tension band suture construct; it retains 80% of its breaking strength at 3 months, is fully absorbed, and maintains osteotomy reduction throughout a passive motion protocol.

Nonunions of the distal radius.

Ten nonunions were treated with open reduction, internal fixation, and iliac crest bone graft (7 bicortical corticocancellous; 3 cancellous) through either a dorsal (8) (6 bicortical; 2 cancellous graft) or a palmar (2) approach (1 corticocancellous; 1 cancellous graft), depending on angulation and collapse. After the procedure, the patients wore casts for 2 weeks and then splints for 2 weeks, after which they progressed from active assisted range-of-motion exercises to active range-of-motion and strengthening exercises. Follow-up averaged 18.9 months (range, 9-45 months). Of the 10 patients, there were 8 unions which attained adequate range of motion of the wrist, as demonstrated by the following averages: flexion, 50 degrees; extension, 38 degrees; pronation, 73 degrees; supination, 58 degrees. Grip strength and key pinch averaged 71% and 86% of the opposite side, respectively. Five patients returned to preinjury activity levels or employed status. Five patients were unable to return to work because of associated injuries and pain (5) and poor wrist function (1). These results indicate that nonunion of the distal radius can be treated with open reduction, internal fixation, and bone grafting, that union can be attained, and that function can be restored.