Forearm Rotation Measurement Device

Mission Statement

Team ENGInuity, Rice Center of Engineering Leadership, Rice UniversityMark Dudley (mwd1), Sharad Jones (skj1), Joseph Song (jls12),

Tanner Songkakul (tps1) & Salvatore Testa (srt6).

We aim to create a device that will rapidly and accurately measure the rotation of the forearm of pediatric patients to allow physicians to improve the quality of patients’ evaluations.

Introduction

Limitations of Current Devices• Goniometer: This protractor-like device relies

on “eyeballing” and is thus too inaccurate since it relies on subjective measurements.

• Motion lab: Although the motion lab is accurate, it costs thousands of dollars for the clinic to operate and is very time consuming since a single measurements lasts minutes.

Design Objectives

Device Prototypes

Testing Method

Testing Results

Conclusions

Future Work

References and Acknowledgement

Figure 1: Brachial plexus injury results in hand/arm limitations.

** All values are for the actual product, not the prototype.

Objective DescriptionWeight < 200 grams

Portability Smaller than 4"x4"x1"Adjustability One size fits all

Accuracy Measures within ±5% of errorEase of use Takes <15 seconds to measure

Durability Withstands 50 drops from 4 feet highCost Less than $50

• We developed two prototypes for effectively measuring forearm rotation: one mechanical and another electrical.

• Initial test results show that the precision of these two prototypes are very promising and may possibly exceed that of the currently used goniometer.

Prototype #1: Integrated Accelerometers

Prototype #2: Mechanical Sliding Loop

• We plan on testing these two prototypes at Shriner’s Hospital on pediatric patients to evaluate their feasibility.

• We will then choose the prototype with more successful results and develop that one further.

Figure 2: A diagram of the design for the electrical components

Figure 3: A diagram of the design for the electrical components

Certain musculoskeletal diseases limit the free rotation of the forearm: •Cerebral palsy - Nervous affliction that causes physical disabilities in development•Brachial plexus injury – Results in shoulder trauma•Muscular dystrophy – Overall muscle weakening

A prototype is fit onto a tube which has

degree marks.

The tube is rotated and the two

measurements are compared.

How it works:•Two Velcro straps with accelerometers are attached: one below the wrist and another below the elbow. •The digital display records the initial angles of the accelerometers.•The arm is rotated and the angles of rotation of the accelerometers are displayed.

Figure 4: The testing method for prototypes

How it works:•The arm through the loops and the cuff attached to it.•The cuff is then inflated until the surfaces of the arm, cuff and inner loop are virtually frictionless.•The patient then rotates his/her arm and pushes a marker while the doctor keeps the outer loop still.

• An ideal prototype would have y = x with a corr. coeff. of 1.• As Fig. 5/6 show, the current prototypes are very precise

devices as they come close to the actual measurements. • Both prototypes also meet all the design objectives

previously stated.

Figure 5/6: Graphs of actual v. measured measurements for both of the prototypes. The closer y is equal to x, the more accurate is the device.

Badawi et al., “What constitutes cerebral palsy?,” Developmental Medicine and Child Neurology 40, no. 8 (August 1998): 520-527. 25 Jan. 2011.Dr. Gogola, Private Communication, January 20th, 2011Range-of-motion Measurement in the Elbow and Forearm. 7.6 (1998): 573-80. J Shoulder Elbow Surgery. Web. 25 Jan. 2011. <http://www.sciencedirect.com.ezproxy.rice.edu/science&ie=/sdar>.

We would like to thank the following people and organizations for their help and support:

OEDK, RCEL, Shriner’s Hospital, Dr. Mark Embree, Dr. Gloria Gogola, Dr. Ann Saterbak, Tracy Volz, Carlos Amaro, Leslie Miller, Andrew Owens, Joey Spinella