Students learn about how biomedical engineers aid doctors in repairing severely broken bones. They learn about using pins, plates, rods and screws to repair fractures. They do this by designing, creating and testing their own prototype devices to repair broken turkey bones.
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- Colorado: Math
- c. Solve for unknown quantities in relationships involving perimeter, area, surface area, and volume (Grades 9 - 12)  ...show
- Colorado: Science
- a. Discuss how two or more body systems interact to promote health for the whole organism (Grades 9 - 12)  ...show
- International Technology and Engineering Educators Association: Technology
- R. Evaluate final solutions and communicate observation, processes, and results of the entire design process, using verbal, graphic, quantitative, virtual, and written means, in addition to three-dimensional models. (Grades 9 - 12)  ...show
- K. Medical technologies include prevention and rehabilitation, vaccines and pharmaceuticals, medical and surgical procedures, genetic engineering, and the systems within which health is protected and maintained. (Grades 9 - 12)  ...show
- Next Generation Science Standards: Science
- Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering. (Grades 9 - 12)  ...show
- Describe how engineers aid doctors in repairing severe bone fractures.
- Create prototype devices to aid in the healing of a bone fractures and test them for strength.
- Evaluate the strengths and weaknesses of a prototype medical device based on model testing.
- Bone Repair Challenge (ppt)
- computer and LCD projector to show a PowerPoint presentation (or make overhead transparencies of the PPT file and use an overhead projector)
- 1 turkey femur (drumstick)
- safety glasses or goggles, one per student
- other supplies, depending on group design (see below)
- Repairing Broken Bones Design Worksheet, one per person
- ~1 yard (~1 m), half-inch diameter steel or aluminum rod
- ~20 metal screws (suggestion: 10 half-inch long plus 10 one-inch long)
- metal strip (sold in coils at hardware stores, usually with plumbing supplies; already has screw holes in it)
- 1-2 extra turkey bones
- other materials or supplies that students include in their designs
- drill (a drill press is preferred, but a hand drill is okay)
- hack saw
- screw driver
- (optional) tile drill bit (makes drilling into bone easier and less likely to crack)
|biocompatibility:||A characteristic of some materials that when they are inserted into the body do not produce a significant rejection or immune response.|
|bone graft:||Bone taken from a patient during surgery or a bone substitute that is used to take the place of removed bone or to fill a bony defect.|
|external fixation:||The process of installing temporary repair supports outside of the skin to stabilize and align bone while the body heals. Examples: screws in bone, metal braces, casts, slings.|
|fracture:||An injury to a bone in which the tissue of the bone is broken.|
|internal fixation:||The process of fastening together pieces of bone in a fixed position for alignment and support, using pins, rods, plates, screws, wires, grafting, and other devices, all under the skin. Can be temporary or permanent fixtures.|
|prototype:||An original, full-scale, and usually working model of a new product, or new version of an existing product.|
Before the Activity
- Purchase enough turkey drumsticks to equal to the number of groups plus one or two extras, the bigger the bones the better. Ask if a butcher or meat plant might donate them. Eat the turkey or remove the meat from the bones.
- To make the turkey femurs as clean as possible, boil them and remove any remaining meat and other tissue. If necessary, soak the bones in a solution of 90% warm water and 10% bleach or ammonia to make cleaning them easier.
- Let the bones dry for ~24 hrs.
- Gather materials and make copies of the Repairing Broken Bones Design Worksheet, one per person.
Day 1: Bone Breaking
- Divide the class into groups of three students each.
- Break the turkey femurs, keeping track of the maximum weight each bone could bear before breaking. Two suggested methods:
- Use a stress tester, such as an Instron universal testing machine, to break bone from the side and/or from compression. Universities often have stress testing equipment.
- Bridge a bone across two desk edges and hang enough weight from the center of the bone until it breaks. Expect a turkey femur to bear up to 200 lbs (91 kg), depending on its size. (This approach is described in more detail as part of the Sticks and Stones Will Break That Bone! activity.)
Days 2-4: Bone Repair
- Challenge teams to design and build repairs for their fractured bones. Encourage them to try to make the bone even stronger than before. Have students follow along with the design worksheet during this process.
- Have students carefully examine the extent and nature of the bone fracture(s), and brainstorm possible ways to repair their broken turkey bones.
- Have students draw two or three engineering designs (sketches) to repair bone. Make sure they label the parts and materials that they intend to use in each prototype design.
- Have students choose their best design and present it to the class. Require presentations to include reasons for their design choices, and engineering advantages and disadvantages (and other factors, as described in the Assessment section). Encourage the rest of the students to provide constructive feedback and suggestions.
- Direct students to begin fixing their bone, as designed. Encourage careful work, bones can be brittle and are not replaceable.
- Have students present their final prototype "products" to the class again. In these presentations, have them explain what steps they took as well as what they would improve upon.
Day 5: Bone Testing
- Have each group predict the performance of their repaired bone.
- Break each reinforced bone using the same method used before.
- Have students record how well their bone resisted the weight compared to its unbroken state. Record how much weight the reinforced bone withstood, and any other observations during the test. Have students complete their worksheets while others complete the stress testing.
- When testing is complete, discuss and compare all results as a class.
- Have students give final presentations, answering questions as described in the Assessment section.
- Have students wear eye protection throughout the activity as bone fragments may splinter and fly.
- Provide proper training and safety measures when using any power tools.
- What are different ways to reinforce a broken bone?
Activity Embedded Assessment
- How does the design support the weight and movement of the patient?
- Is it minimally invasive (easy for a doctor to implant)? Why or why not?
- Are the materials biocompatible?
- Is it realistic?
- What are the design strong points and weaknesses?
- Which design did you choose? Why?
- How did your repair handle the load during testing?
- Where on the bone did the repair fail? Why do you think it failed there?
- How could you have improved your device?
- For lower grades, have students work on smaller bones, such as chicken wings. Or conduct the fourth-grade Sticks and Stones Will Break That Bone! activity, which includes a class demonstration to break a chicken bone by applying a load until it fails (fractures), followed by student teams acting as biomedical engineers, designing (on paper) their own splints or casts to help mend fractured bones.
- For lower grades, have students repair their bones solely with external fixation, such as bracing, casts or splints.
Bone fracture repair-series, Procedure. Last updated September 21, 2009. MedlinePlus Medical Encyclopedia, US National Library of Medicine, National Institutes of Health. Accessed October 29, 2009. http://www.nlm.nih.gov/medlineplus/ency/presentations/100077_3.htm
Prototype. The American Heritage® Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company. Accessed November 2, 2009, from Dictionary.com website. http://dictionary.reference.com/browse/Prototype
Todd Curtis, Malinda Schaefer Zarske, Janet Yowell, Denise W. Carlson
© 2008 by Regents of the University of Colorado.
Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Last modified: March 27, 2015