Innovative Radioulnar Instability Screening Tool - Project Recap & Specifications

R.I.S.T: Radioulnar Instability Screening Tool Group 24: Saketh Balmoori Kaitlyn Thornton Chris Wissmann 1

Project Recap & Modifications 2

Project Recap The Distal Radioulnar Joint (DRUJ) connects the radius and ulna at the wrist Responsible for stabilizing articulation of the radius around the ulna during pronation and supination1 Triangular Fibrocartilage Complex (TFCC) injuries are a leading cause of DRUJ instability2 No devices capable of DRUJ instability quantification currently exist on the market Creating a reliable, non-invasive diagnostic device would better inform surgical decision making and improve patient outcomes 3 1. Black, Varacallo. Statpearls, 2024 2. Allen. Orthobullets

Spec Updates 1. Device dimensions: < 20 x 20 x 20 cm to < 40 x 40 x 40 cm 2. Adjustability ranges for the actuation mechanism: Wrist thicknesses from 2-8 cm with a minimum of 1 cm of vertical clearance on either side Palm rest is horizontally adjustable along the arm in a 15 cm range. 3. Medical Standards selected: ISO 13485:2019 - Medical device quality management ISO 14971:2016 - Medical device safety & risk management ISO 9001:2015 - General device quality management 4

Design Options 5

Main Rig The following options were considered for the Main Rig of the device: Gauntlet - Heavy-duty limb bracer External Glove - Examiner s gloves with fingertip sensors Box + Bracer - Limb bracer combined with metal chassis Box - Standalone metal chassis 6

Main Rig - Analysis Notable Criteria: 9 Total Criteria MeasurabilityRigidity, and Adjustability considered most valuable Notable Qualities: Box won Cost and Measurability Box lost Weight Selected Main Rig: Box 7

Actuation Mechanism The following options were considered for the Actuation Mechanism of the device: Rotational Eccentric Cams (A) - Set of four oblong cams Linear Transducers (B) - Set of four motorized pistons Dual Clamp (C) - Set of half-cuffs linked to two linear transducers 8

Actuation Mechanism - Analysis Notable Criteria: 8 Total Criteria Data Acquisition, Adjustability, Contact Stability, Safety considered most valuable Notable Qualities: Linear Transducers won Adjustability and Data Acquisition Linear Transducers lost Contact Stability, Packaging Dimensions, Cost Selected Actuation Mechanism: Linear Transducers 9

Translation Measurement (1/2) The following options were considered for the Translation Measurement of the device: Ultrasound - An axial cross section of the wrist determining translation via ultrasound, which is shown in previous literature to be extremely accurate Wrist-Mounted Laser Reflector - Vertical striped measurement guide attached to wrist cuff that reflects a laser onto light sensor Structured Light - Coupled projective light source and 3D vision scanning system to map shape & depth changes 10

Translation Measurement (2/2) The following options were considered for the Translation Measurement of the device: IR Markers - IR Markers adhered to wrist using boney landmarks on patient's wrist during translation Software Rigidification - Software recalculation that takes displacement data and accounts for soft tissue artifacts, can be combined with previous technologies Actuator Translation Tracking (ATT) - Back-End internal measurement from software that takes actuator feedback (or other sensing modality) to determine bone displacement 11

Translation Measurement - Analysis Notable Criteria: 9 Total Criteria Accuracy, Feedback Delay, Hardware Complexity considered most valuable Notable Qualities: ATT won Feedback Delay, Cost, Patient Prep Time, Software Complexity ATT lost in no categories Ultrasound scored especially high for most valuable categories, but comparatively lower to FSIAC across the spectrum Selected Translation Measurement: ATT 12

Force Measurement The following options were considered for the Force Measurement of the device: Force Resistive Sensors - Contact sensors placed on actuator surfaces Strain Gauge Load Cell - Mechanisms that sit between actuators and direct point of contact and measure strain Electrical Current Back-Calculation - Back calculating the input current and power with the given torque value of a transducer or motor can give an accurate indication of force applied 13

Force Measurement - Analysis Notable Criteria: 8 Total Criteria Accuracy, Feedback Delay, Hardware Complexity considered most valuable Notable Qualities: Force Resistive-Sensor won Computational Requirements Force Resistive-Sensor lost in no categories Selected Force Measurement: Force Resistive Sensor 14

Chosen Design 15

Chosen Combination Chassis/Box Linear Transducers ATT Force Resistive Sensors 16

Chosen Combination Chassis/Box Linear Transducers ATT Force Resistive Sensors 17

Chosen Combination Chassis/Box Linear Transducers ATT Force Resistive Sensors 18

Chosen Combination Chassis/Box Linear Transducers ATT Force Resistive Sensors 19

Chosen Combination Chassis/Box Linear Transducers ATT Force Resistive Sensors 20

Chosen Combination Chassis/Box Linear Transducers ATT Force Resistive Sensors 21

Chosen Combination Chassis/Box Linear Transducers ATT Force Resistive Sensors 22

Proposed Budget 23

Budget Breakdown Major Subsections: Actuation accounts for $424.91 Translation Measurement accounts for $19.80 Chassis accounts for $333.54 Electronics accounts for $133.41 Misc. accounts for $100 Notable Expenses: Linear Transducers Extruded Aluminum Bars Linear Motion Rods 24

Thank You! Questions? 25

Appendix 26

Category Specification Sensitivity < 0.5 mm joint displacement Testing Setup Comfort adjustable resting height accommodate varying wrist sizes Sensor Implementation Non-invasive epicutaneous accurate for multiple wrist diameters Isolation Vibrationally isolated (<0.1mm) Electrically isolated Dimensions < 20 cm x 20 cm x 20 cm Data Output Universal: .csv or .txt filetype Operation Regulations Easily operated with low learning curve Tactile buttons, clean interface Large, readable display 27

Category (continued) Specification (continued) Safety Hypoallergenic, sanitizable Repeatable tests without patient injury Easy to remove hand physical + software shut-off switches Applicable Force Input + Range Granular and customizable: 0-20 N with 0.25 N resolution input-to-actuation lag time of <1 sec Mounting System Static/acute mounting for forearm to completely prevent unwanted rotation Sampling Rate 100 samples/sec Real-time force/translation readout Rig Chirality Ambidextrous Dorsal and volar force application Cost < $1000 28

Control Scheme Block Diagram 29

Testing Scheme Overview 30

Basic Control Pseudocode 31