Our Design Package

Background information

The shoulder joint is the most mobile joint in the human body. That being said, the shoulder often sacrifices stability in favor of mobility. It’s complicated makeup includes eight muscles. Four muscles connect the humerus to the scapula: supraspinatus, infraspinatus, teres minor, and subscapularis (SITS). (1) With proper function, these muscles hold the humeral head in the socket of the shoulder. (2) Injury of these four muscles is common and often results in shoulder reconstruction surgery. Physicians and physical therapists monitor recovery by testing the strength of these muscles. (1)

project objective

During a patient’s recovery from a shoulder injury, medical professionals need a way to quantify the progress. The current methods of measuring recovery are either inaccurate or do not record the patient’s range of motion. To resolve this problem, a device must be created that measures both the patient’s muscle force output and mobility. The solution to this problem incorporates a frame and a force transducer to create repeatability and precision when testing muscle strength after shoulder reconstruction surgery.

Design Constraints

There were five design constraints presented in the project. First, the device must be placed in any doctors office or physical therapy facility keeping in mind the importance of patient confidentiality. The device must adapt and accommodate to different positions depending on each patient’s body physique. The device must include the ability to measure forces when the patient’s arm is fully extended at 30, 45, 60, and 90 degrees for abduction and adduction testing (3). Also, the device must include the ability to measure internal and external rotation forces when the patient’s arm is at their side while bent at a 90 degree angle. The calibrated force measurement results must be transported via Bluetooth reading capabilities to an Android application.

Design solution

  • The design solutions met all of the constraint requirements.
  • The Stable platform located at the base of the frame for the placement of a chair
  • Adjustable shoulder heights set by vertical placement of the angulation controller and the arm
  • Adjustable arm lengths set by horizontal placement of the load cell box on the arm
  • Four different angle testing options determine the placement of the arm on the angulation controller
  • Load cell box can be placed on all four faces of the arm for abduction and adduction movement as well as internal and external rotation

future plans

  • Order materials
  • Fabricate prototype based off of current design
  • Write Arduino code for force sensor readings based on flowchart logic
  • Create Android application to display maximum and average force output of the load cell
  • Calibrate sensor voltage to force output
  • Integrate Arduino code and the Android application
  • Test precision and repeatability of the strength tester once complete

references

  1. Muscular System - Muscles of the Human Body. (n.d.). Retrieved from http://www.innerbody.com/image/musfov.html
  2. Matsen, F. A., III. (n.d.). Reverse Shoulder Replacement for arthritis and massive rotator cuff tears. Retrieved from http://www.orthop.washington.edu/?q=patient-care/articles/shoulder/reverse-shoulder-replacement.html
  3. Ellenbecker, T. S., Elmore, E., & Bailie, D. S. (2006). Descriptive Report of Shoulder Range of Motion and Rotational Strength 6 and 12 Weeks Following Rotator Cuff Repair Using a Mini-Open Deltoid Splitting Technique. Journal of Orthopaedic & Sports Physical Therapy, 36(5), 326-335. doi:10.2519/jospt.2006.2191

Electrical deisign


flowchart logic

Preliminary Code

a = arduino ('com3','uno')

analogVoltage = zeros (1,100)

for index 1 :100

analogVoltage(index) = readVoltage (a,'A0")

end

Flowchart

bill of materials

appendix