Pulley and Tendon Project

Work in process – Title to be revised! 


When I was young, I admired my father’s hands. Every muscle was defined, as if Leonardo Da Vinci had sketched them to be. They were the working hands of a neurosurgeon and on rare occasion, a pianist. Strong, precise and soft. One of the doctors at my clinic shared my fascination for the hand. When he found out that I had a New Media education, he expressed a wish to fabricate a functional hand model in the hopes of helping Medical Residents learn subtle hand pathologies (Mallet Finger, Climber’s Finger and Trigger Finger). 


Upper extremity injuries are the 3rd most common work injury according to WSIB 2016 (1). The fingers are the most common region of the upper extremity to present for care in U.S. emergency departments (2). Due to the high incidence of upper limb injuries and the ubiquity our hands play in our everyday lives, can I make an interactive 3D hand model that will aid in diagnosis and treatment of complicated hand injuries?

The Process

Initially I thought I could recruit someone from the University of Ottawa to help design the hand. But this idea was abandoned early on as I was contemplating the demands on Undergraduate Education and reflecting on my own immaturity at that time. So I decided to take on as much as the project as possible. Since my programming skills are basic and rusty. I search the web for already made hand models in places such as Instructables. Some good upcycling included finds1. finds2. finds3. I tried them all but straws, scotch tape and tubing (I bought the wrong kind of tubing!) is not durable and I couldn’t get the wow factor. As a result I decided to try 3D printing. I printed some correctly scaled hand bones from Thingyverse using the 3D printer at my school’s library. Sadly, the printer was not detailed enough and the prints were warped and useless. Luck I came across HendoJ‘s design, the 3D Printed Bionic Hand Skeleton. He was nice enough to share it on Instructables. It provided a very good framework but the placement of the pulleys had to be tweaked. So I contacted MadeMill – by prototypeD (a publicly funded company that no longer exists) in Ottawa to employed them to modify the code and print it. The file type HendoJ used proved to be labour-intensive/very expensive to modify. We went through 3 prototyes then I ran out of funds and the company’s grant term ended (because it was publicly funded). I am very pleased on the result. Now that the hand is composed, I followed HendoJ’s list of materials. Finding screws to his specification was harder than anticipated. I had to get them custom ordered and I will still need to file them down to the right size. Furthermore, the nut projects out and interferes with the flexor tendons. 

The Big Test!

Once the kinks are sorted. My plan is to unleash it on Bruyere and Primrose Family Medicine Residents, approximately 30 students. Have them play with it individually and then answer a survey to measure ease of learning the hand pathologies (Mallet Finger, Climber’s Finger and Trigger Finger).

The End Game

My hope is that it will add clinical value. Of course any added teaching will improve knowledge, however in this experiment there is no instruction to the hand model. All the learning will be student driven as they interact with the model. The hope being that having access to a model would facilitate self-directed learning.



Images 1,2,3 from my work in progress Tendon and Pulley Project.

Technical Drawings including the changes to the original files.


  1. Report Builder, By the Numbers. WSIB CSPAAT Ontario, http://www.divxy123.ca/ReportBuilder2016/Pages/prep2016private/generate_report.php
  2. Ootes, D., Lamber K. and Ringer D. The epidemiology of upper extremity injuries presenting to the emergency department in the United States. Hand (NY). 7(1) 18-22. 2012. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3280373/

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