A High-fidelity Tactile Hand Simulator as a Training Tool to Develop Competency in Percutaneous Pinning in Residents

Experimental evaluation of impact-resistant gloves using surrogate hands

Injuries to the hand and fingers with varying degrees of severity are widespread in industries such as mining and oil and gas production. This study presents the results of tests carried out to measure the impact performance for commonly used impact-resistant gloves (metacarpal gloves). Sets of surrogate hands made out of a 3D-printed skeletal structure and soft tissues represented by synthetic gel were manufactured and subjected to controlled impact tests. The calibration and validation of the surrogates were based on impact response data reported previously for cadaveric specimens. Calibrated surrogate hand specimens were tested to assess the impact protection of typical metacarpal gloves. Each type of metacarpal glove provided different levels of protection measured by the decrease in the peak impact reaction force and the fractures detected after the impacts. Results indicated that surrogate specimens suffered fractures in 77% and 33% of the impacts for unprotected and protected hands, respectively.

Mechanical Characterization of Synthetic Gels for Creation of Surrogate Hands Subjected to Low-Velocity Impacts

The development of human body simulators that can be used as surrogates for testing protective devices and measures requires selecting synthetic materials with mechanical properties closely representative of the human tissues under consideration. For impact tests, gelatinous materials are often used to represent the soft tissues as a whole without distinguishing layers such as skin, fat, or muscles. This research focuses on the mechanical characterization of medical-grade synthetic gels that can be implemented to represent the soft tissues of the hand. Six grades of commercially available gels are selected for quasi-static hardness and firmness tests as well as for controlled low-velocity impact tests, which are not routinely conducted by gel manufacturers and require additional considerations such as energy level and specimen sizes relevant to the specific application. Specimens subject to impacts represent the hand thicknesses at the fingers, knuckles, and mid-metacarpal regions. Two impact test configurations are considered: one with the gel specimens including a solid insert representing a bone and one without this insert. The impact behavior of the candidate gels is evaluated by the coefficient of restitution, the energy loss percentage, and the peak reaction force at the time of impact. The resulting values are compared with similar indicators reported for experiments with cadaveric hands. Relatively softer gels, characterized by Shore OOO hardness in the range of 32.6 ± 0.9 to 34.4 ± 2.0, closely matched the impact behavior of cadaveric specimens. These results show that softer gels would be the most suitable gels to represent soft tissues in the creation of surrogate hands that can be used for extensive impact testing, thus, minimizing the need for cadaveric specimens.

3D Printing of Customizable Phantoms to Replace Cadaveric Models in Upper Extremity Surgical Residency Training

Medical phantoms are commonly used for training and skill demonstration of surgical procedures without exposing a patient to unnecessary risk. The discrimination of these tissues is critical to the ability of young orthopedic surgical trainees to identify patient injuries and properly manipulate surrounding tissues into healing-compliant positions. Most commercial phantoms lack anatomical specificity and use materials that inadequately attempt to mimic human tissue characteristics. This paper covers the manufacturing methods used to create novel, higher fidelity surgical training phantoms. We utilize medical scans and 3D printing techniques to create upper extremity phantoms that replicate both osseous and synovial geometries. These phantoms are undergoing validation through OSATS training of surgical residents under the guidance of attendings and chief residents. Twenty upper extremity phantoms with distal radius fracture were placed into traction and reduced by first- and second-year surgical residency students as part of their upper extremity triage training. Trainees reported uniform support for the training, enjoying the active learning exercise and expressing willingness for participation in future trials. Trainees successfully completed the reduction procedure utilizing tactile stimuli and prior lecture knowledge, showing the viability of synthetic phantoms to be used in lieu of traditional cadaveric models.

Simulation in Hand Surgery: A Literature Review

BACKGROUND

Due to duty hour regulations, patient safety and inadequate operative time simulation have become a necessary part of surgical education and training in residency. Currently, there is no formal adoption of simulators for the use of surgical education or assessment in hand surgery. This literature review analyzes that the simulation techniques established thus far in hand surgery.

METHODS

A comprehensive literature search was performed on PubMed. Search results were filtered by title and abstract to isolate articles that were relevant to simulation in hand surgery. Articles that were nonspecific to the hand, non-English and cadaveric were excluded. Additional articles were identified through references from the initial search.

RESULTS

A total of 1192 articles were yielded from the initial query. After the application of the inclusion criteria, this was narrowed down to 28 articles. Another 8 additional articles were excluded as they did not pertain to the hand although the simulators could be adapted for hand surgery. A total of 20 articles were included in this study.

CONCLUSIONS

Surgical simulation is a growing and essential field of surgical education. Simulators in hand surgery are limited and require further research and validation. Like other surgical subspecialties, hand surgery may benefit from the adoption of an official simulation curriculum for the assessment of residents and enhancement of technical skills.

A 3-Dimensional-Printed Hand Model for Home-Based Acquisition of Fracture Fixation Skills Without Fluoroscopy

OBJECTIVE

To design a low cost ($40), realistic and fluoroscopy-free percutaneous Kirschner wire hand fracture fixation training instrument kit for home-based skill acquisition during the COVID-19 pandemic.

DESIGN

A 3D-printed hand was designed from a computed tomography scan of a healthy hand. These data were used to create replaceable hand and wrist bones and reusable silicone molds for a replica of the soft tissue envelope. The model is currently being integrated into the simulation curriculum at 2 integrated plastic surgery residency programs for training in percutaneous wire fixation of hand fractures.

SETTING

Brown University, Warren Alpert Medical School of Brown University. Department of Surgery, Division of Plastic and Reconstructive Surgery. Large academic quaternary referral institution. Yale University, Yale School of Medicine. Department of Surgery, Division of Plastic and Reconstructive Surgery. Large academic quaternary referral institution.

PARTICIPANTS

PGY 1-4 plastic surgery residents preparing to meet ACGME Accreditation for Graduate Medical Education hand surgery specific milestones.

RESULTS

A realistic and durable 3D model with interchangeable bones allows trainees to practice the key motor skills necessary for successful fixation of hand and wrist fractures with K-wires in a home-based setting.

CONCLUSIONS

A low cost, realistic and durable 3D hand model with interchangeable bones allows easy integration into any home-based hand surgery curriculum. With 3D printers and programming becoming more prevalent and affordable, such models offer a means of low-cost and safe instruction of residents in fracture fixation with no harm to patients.