1. Bowleggedness Correction Brace University of Pittsburgh Senior Design – BioE 1160/1161 Amy Macevoy Daniel Steed Lauren Wolbert Sarah Wyszomierski April 18, 2006 Mentor: Morey S. Moreland, M.D. Children’s Hospital, UPMC

2. Background Redesign of pediatric bowleggedness correction brace Focus: Correction and Support for Blount’s disease (tibia vara) Bowleggedness (genu varum) Rickets Children 2-13 years old Specifically, 6.5 – 10.5 yrs

3. Background In U.S., ~ 277,000 children have severe bowleggedness (Frost & Sullivan) Improper growth in femur and tibial growth plates Rickets occurs most often in malnourished children eg.) In Mongolia, 32.1% of children under 5 (UNICEF) disorder, usually in children, involving softening and weakening of the bones caused by lack of vitamin D, calcium, or phosphate

4. Problem Statement Current devices are expensive, non- adjustable, custom-molded Outgrowth: rapid, frequent Too expensive for low income households (up to $3,500) Also applicable in 3rd world countries Project goal: Redesign pediatric bowleggedness correction brace Applies forces to correct angle of tibia and femur growth plates Adjustable Affordable Lightweight/Non-bulky

5. Design Requirements Material Inexpensive Easy to acquire Durable Design Simple to machine and assemble Plans to orthotists, companies Parts easily acquired and replaced Correction 3 point system Corrective force at knee Counteracting forces for stability

6. Design Requirements, cont’d Design, cont’d Adjustable Interchangeable b/w R and L leg Length Circumference S/M/L braces Medium (5th – 95th percentile, 6.5 – 10.5 yrs) Lightweight < 2.3 kg (5 lbs) Affordable < $300 per brace Comfort Reduce occurrence of pressure sores

7. Economic Considerations Significantly lower price Up to $3,500 vs. ~ $250-300 Not custom molded Adjustable Market size ~$83 million market LSGH (Frost & Sullivan Reports) Distribution Medical supply companies Private Orthotists and Rehabilitation Specialists

8. Initial Design Considerations Design Problems: Lack of: Support and correction at knee Straps to secure Foot interface Wanted sturdier design Nested tubing Too heavy Difficult to acquire correct dimensions Version 1.0 Version 1.1

9. Initial Design, cont’d  Proposed Solution Too many adjustment holes Difficult to machine Version 2.0 Version 2.1

10. Correction: 3 pt system (shown in gold) Easily machined, common materials: Aluminum 6061 Alloy Side holes Velcro/Neoprene straps Grommets, elastic Machine screws/washers/bolts Lock washers Optional padding Washable Water clog Breathable Waterproof Inexpensive Design Solution

11. Prototype Fabrication Milled/Drilled Beams Insert strap grommets for adjustability Insert padding FINAL PRODUCT Drilled Shoes Trim bolts

12. Experimental Methods Used to Test Device Performance Human Subject Testing Comfort Usability Strap Corrective Pressure Materials Testing COSMOSWorks testing Deformation Factor of Safety

13. Experimental Methods- Human Subject Testing 1 Human Subject Volunteer Male, 9 yrs 9 mos Height: 54” (60 th percentile) Weight: 70.5 lbs (50 th percentile) Subject fitted with brace Insertion of Pressurex-Micro pressure transducer film to record corrective pressure values Standing for 10 minutes Walking for 2 minutes

14. Comfort Subject answered survey questions, based on a scale of 1 to 5: How uncomfortable are you feeling? (5 = most discomfort) How much do you feel the brace is slipping as you walk? (5 = most slipping) Do you feel that the heaviness of the brace is keeping you from moving normally? (5 = most hindering) Overall, how comfortable do you feel in the brace? (5 = most comfortable) ** “No discomfort” does not imply “comfort” Usability Gait alterations Slipping of straps Experimental Methods- Human Subject Testing

15. Pressure Transducer Film Readings Analyzed using Matlab program Converts scanned film.jpg to grayscale Uses reference image and scaling factor to interpret grayscale values as pressure values within input range Determined: Average maximum pressure (highest 10% of values) Average overall pressure Experimental Methods- Human Subject Testing

16. Comfort & Usability Results COMFORT: Subject answered survey questions, based on a scale of 1 to 5: Discomfort = 2 Slipping = 1 Heaviness = 1 Comfort = 3 USABILITY: Altered gait pattern Walked with slight limp No slipping of straps

17. Pressure Results Pressure in Corrective Straps (psi) StrapMeanMax Calf10.6017.92 Knee13.5319.84 Thigh11.1519.69 Calf Knee Thigh Highest concentration of max values occurred approx. at points of varus/valgus pressures

18. Discussion – Human Subject Testing Comfort Overall, minimal discomfort, slipping, and hindrance due to heaviness Sources of Error: Subject pool size Use of able-bodied child Unaccustomed to brace usage Responses from children may be skewed Usability Limp severity may be due to uneven foot height No slipping Allows for normal activity

19. Discussion – Human Subject Testing Pressure Mean pressure < Literature skin breakdown values ~ 15 – 35 psi Highest values at knee (as compared to calf and thigh) Angle corrected Targeted location of max pressure concentrations Sources of error: Subject pool size, no specified conditions Film handling Reference to grayscale Uses: Fitting Correction progress

20. Experimental Methods – Materials Testing COSMOSWorks Testing Each beam fixed on ends at bolt placement Pressure applied at corrective force strap interface ~ Average pressure ~ 20 psi (max pressure) Analyzed for Deformation Factor of Safety

21. Materials Testing Results PressureDeformation Factor of Safety Average0.000 811 in8.1 Maximum 0.001 548 in 4.7 COSMOSWorks Results

22. Discussion – Materials Testing Small values for deformation Determined to be insignificant Will not affect integrity of brace High factors of safety Desirable FOS values are those that are > 1 FOS > 1 represents how much the stress is within the allowable limit Value > 1 for average pressures Value > 1 for maximum pressures

23. Competitive Analysis Custom-Molded HKAFO (Hip- Knee-Ankle-Foot Orthosis) DeLaTorre O & P ~$1,400 KAFO, Metal (Knee-Ankle Foot Orthosis) DeLaTorre O & P $795

24. Competitive Analysis Strengths Affordability Adjustability Modularity Pieces may be replaced and moved without full brace replacement Weaknesses Not custom molded May hinder comfort, exact fit Aluminum 6061 beam $12 Neoprene/ Velcro Straps $109 Nuts/Bolts/ Washers $6.50 Shoe$3.50 Padding$13 Pressure film$13.67/patient Manufacturing$31 Grommets$9 TOTAL COST$197.67

25. Constraints limiting Phase I testing Economic Pressurex-Micro transducer film reader ~$4000 Resources/Regulatory Human Subject Testing Need more subjects, with specified conditions Long-term testing to assess correctiveness Gait testing with motion capture Lower body kinematics Materials Testing Repetitive motion testing for durability

26. FDA Regulation TITLE 21--FOOD AND DRUGS CHAPTER I—FOOD AND DRUG ADMINISTRATION DEPARTMENT OF HEALTH AND HUMAN SERVICES PART 890-Physical Medicine Devices Subpart D--Physical Medicine Prosthetic Devices Sec. 890.3475 Limb orthosis (a) Identification. limb orthosis (brace) is a device intended for medical purposes that is worn on the upper or lower extremities to support, to correct, or to prevent deformities or to align body structures for functional improvement. Examples of limb orthoses include the following: A whole limb and joint brace, a hand splint, an elastic stocking, a knee cage, and a corrective shoe. (b) Classification. Class I (general controls). US Food and Drug Administration: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.c fm

27. Pre-existing Devices and Patents Majority: custom molded wide variety of devices, as well as device components, already existing some with patents Regulation

28. Quality System Considerations Manufacturability Simple Design Common components Easy assembly Human factors Anthropometry Collected data for children to determine proper sizes (used 5 th - 95 th percentile data for medium size) Shoe interface Breathable Waterproof Soft material (contours to individual) Optional padding Washable Straps Adjustable Comfortable fit

29. January Improved sketches Ordered materials February Finalized sketch Ordered pressure sensors Practiced testing (using pressure sensors) Completed market analysis March Finished acquiring materials Fabrication April Finished design/fabrication improvements Completed testing Finalized documentation Schedule

30. Group Task Breakdown Amy Market and Competitive Analysis Background/Statistics Clinical Correspondence Dan Design Market Research Materials/Fabrication Human Subject Recruitment & Testing Mentor Correspondence Lauren Initial Design COSMOSWorks testing Human Factors Analysis Sarah Final Design & Anthropometry Materials/Fabrication Human Subject Testing & Analysis Clinical Correspondence

31. Future Design Improvements Improved locking knee joint More cost-effective straps Neoprene sheets ~$30 : Reduce overall price by $80 Improved shoe interface Threaded inserts: reduce shearing in shoe sole Materials testing to find more optimal beam material/fasteners Improved system for reading pressure Formulate instructions for fabrication and use Sent to companies, orthotists, 3 rd world countries, etc.

32. Acknowledgements Morey S. Moreland, M.D. Children’s Hospital of Pittsburgh, UPMC April J. Chambers Human Movement and Balance Lab Gregory R. Frank Augmented Human Performance Lab Kevin McNulty McNulty Landscaping & Handyman Services Brian Wlahofsky Human Subject Testing Beverley Welte Life Sciences Greenhouse The generous gifts of: Dr. Hal Wrigley Dr. Linda Baker