A new opportunity to improve gait in patient's with cerebral palsy
WEEKLY REPORTS
Updates on the current status of the design process
WEEK 3 REPORT
September 14, 2018
This week we were each tasked with finding some research articles and patents related to our design. We met on Tuesday to discuss our articles and our project scope and think of questions to ask Courtney Dunn for the next time we met. Through discussing our research and trying to come up with a scope we came to the conclusion that there were more or less two ways to take this project; one was more of a design based project where we would try to improve on the design of existing AFO's through making them lighter, easier to wear, more fashionable perhaps, and the other involved creating an AFO that would correct for the common gait problems seen in kids with cerebral palsy such as foot slap and toe drop. We decided that this second approach would be better suited for our project, and upon talking to Courtney on Thursday 9/13, she agreed that this is what she wanted and gave us a few suggestions of current AFO's to look up for ideas (SureStep, DAFO turbo). Our main challenge now is trying to figure out if there are any other AFO's like this that currently exist, and if so what could improved upon them or why are there none that exist. One of the articles that we found was about an AFO device used angle sensors and force plates to correct for some of these common gait problems, but the device was mainly just used for research and never was commercially available in the form described in the paper.
From this research, we established a baseline understanding of the current AFO models on the market and the relative advantages and disadvantages of each design. We discovered different physiological testing methods for analyzing the benefits and improvement provided by the AFO, namely gait speed, foot slap and toe drop angles, forceplates, stride length, step length, cadence and sagittal plane motion of the pelvis. Some of this testing protocols could be used to test the functionality of our final product.
Questions
What source of energy/ power will our brace use to cycle the brace through a state of dorsiflexion and plantar flexion?
Will we be able to 3D print our designs or is it better to acquire recycled AFOs and re-design them or add to them?
Is it a better approach to create an attachment for an AFO or create an entirely new model?
WEEK 4 REPORT
September 21, 2018
Met to redo project scope and discuss more quantitative measurements for design specifications
More clearly defined the goals of the project to create a preliminary approach to the project
Research on proprioception complications in kids with CP
Examining the design criteria and selecting an appropriate material for an orthotic is critical to its success. Initial considerations that must be taken into account include the doctor’s diagnosis and patient history including weight and lifestyle. This information is critical to making a correct material choice. Next, the type of orthotic must be determined: functional or accommodative. Functional orthotics control the food, while accommodative minimize change to foot function. Functional orthotics are made of firm materials like carbon graphite composites, while accommodative orthotics are made from less rigid materials like Thermocorks. This presents a challenge, as these materials are quite bulky. Armed with understanding of the goal of the orthotic, a material can be chosen. Options have been researched and include cork, polyethylene foams, thermoplastics, polypropylene, subortholen, and more. These options will be discussed with Orthopedic Groups we will reach out to and with Courtney Dunn
WEEK 5 REPORT
September 28, 2018
This week consisted of us doing further research into existing AFOs, specifically the design specifications as this is where we need to improve the most. We have also begun to think about our preliminary report and divide up responsibilities. We are having a meeting on Friday 9/28 to discuss our preliminary report and design specifications, particularly what metrics will be used. Next week will consist of our group writing up the report and preparing for the first presentation.
WEEK 6 REPORT
October 5, 2018
This week consisted of our group working on our preliminary report. We divided up the research into the background and existing solutions among group members, then came together to compile our findings into a cohesive report complete with our need statement/project scope, design spec, and Gantt chart. The report will be turned in by Friday at 12 to both the BME office in Whitaker and Canvas.
Looking Ahead:
There are a few action items that we have on our agenda for the upcoming weekend and next week:
Develop our presentation slides for Monday’s presentation; Dom will be presenting.
Contact orthopedic labs around St. Louis to try and meet to discuss our ideas and see what insights they may offer.
Design the website and get it online, adding all of our existing components
WEEK 7 REPORT
October 12, 2018
This week consisted of Dominique presenting on our preliminary report during class on Monday. The whole group worked together to develop the slide deck on Sunday and helped Dominique prepare. Since the preliminary report and presentation our group has started thinking about our design and how we are going to meet our goals. Our main design considerations at this point are thinking about what mechanical elements are needed to fulfill our design specifications and how we will be combining these elements into a device. This week has not been as busy with the project after the presentation, but after fall break we plan to meet and brainstorm more specifically about design as well as designing our webpage.
WEEK 8 REPORT
October 19, 2018
This week our group communicated mainly via text and email, as we were on fall break until Tuesday and then on Wednesday all three members left for the Society of Women Engineers annual conference. Although we were unable to meet in person, we discussed some ideas about how we are going to achieve our design goals. We have been reconsidering the idea of addressing the existing problem via an AFO attachment rather than building a new AFO itself. With this consideration comes many additional design specifications to consider, especially with the idea that there would be electric components involved. Some of these involve:
Safety of electrical components (what protections are needed to ensure that the user does not come into harmful contact with them?)
Necessary power of electrical components
Will a battery be needed?
Programming of electrical components
Ideally, we will be able to program the motor to move at different points in the gait cycle, so we need to write code to ensure that the timing is correct
There are a lot more things to consider, which we intend on discussing with some of the orthopedic groups that we will be meeting with soon. Hopefully as we flesh out this idea more we will be able to start on the CAD design of the product in the coming week.
This week we also worked on creating our website so that we can have it ready by Monday. All three of us are working on the appearance and what content we think is most important to include.
WEEK 9 REPORT
October 26. 2018
This week our group continued brainstorming possible design solutions. Our goal is to have at least five ideas relatively thoroughly fleshed out by the end of next week, so we can begin to do some CAD renderings to really compare the designs. So far these are what we have thought of.
Attachment to AFO via modification of the hinge
We have been thinking of ways to mechanically do this so we wouldn’t have to include an electrical component
Construction of entire AFO with embedded “attachment”, with both sensor component and active force component
Drop foot brace show attachment
Essentially a strap between the users shin and top of their foot that can prevent drop foot. There many devices like this on the market already, but we would be modifying it for the specific needs of patients with CP
Next week we will be meeting with Courtney, our client, to discuss our progress and what she would like to see moving forward.
WEEK 10 REPORT
November 2, 2018
This week our group met with our client, Courtney Dunn, to discuss her thoughts on our preliminary report and our continuing project. We were pleased to hear that she was excited about our ideas moving forward, and even was able to offer some assistance in the construction and testing of a device. Otherwise, we have continued thinking of different designs, currently looking at how existing solutions can be modified to better serve the needs of the users, especially those with problems of drop foot specifically. We have been able to expand our scope of thinking since Courtney has offered help in the building process, so we are excited to have a wider range of design options available to us as we continue forward.
WEEK 11 REPORT
November 9, 2018
This week we continued brainstorming design ideas. Below are some of our main ideas that we have so far.
Creating a strap that attaches to top of the shoe and part on the shin, but add a gear/spring mechanism that you can set to a certain active force level to the portion near the shin
force would be generated in the spring during dorsiflex, have to figure out the k value for the spring, would need to test different ones and calculate how much force each generates, then think about how much force (in N) is actually needed, which could depend on the existing strength of the patient, which is why being able to set to a certain level (via a settable gear or something similar) would be necessary/helpful
Pressure responsive systems (this idea needs to be fleshed out a bit more, the biggest challenge would be implementing pressure sensors that aren’t electrical
Double spring hinge with active component
using strong elastic material common in current AFOs
pressure of foot contacting floor provides a "switch" mechanism to change the current elastic support direction
There are a few other ideas that are in the works, such as creating a prosthetic limb specifically for correcting gait cycle.
WEEK 12 REPORT
November 16, 2018
This week our group met with our client, Courtney Dunn in order to gauge her most important design specifications so that we can consider them in our Pugh Chart. Courtney said that her most important specs were that the device be adaptable, lightweight, easy to use, and cost effective. This gives us a basis for our Pugh chart and how we should pick our final design based on all the alternatives we have brainstormed. We have also began working on the progress report writing and made our brainstorming more concise by breaking down all of the information into concrete ideas that can be separately described.
WEEK 14 REPORT
November 30, 2018
This week our group worked exclusively on writing our progress report. We met every day to finalize our design alternatives and ensure that we are describing them in a clear, concise way. The design that we have decided to go with is a Spring Assisted Foot Pad. Below is the description of the device that is included in our progress report.
A possible mechanical approach that provides active support during the toe-off phase of the gait cycle involves a passive spring system and a hinge. This spring system attaches to the bottom of the user’s HAFO and is adapted to fit a range of orthotic sizes. Elastic energy is stored in the spring as the user initiates contact with the ground during the heel strike of the gait cycle. As the user lowers his or her foot and begins to bear weight, the device is compressed into a linear position to obtain flat contact of the foot with the ground, thus avoiding interference with the natural gait cycle. Then, as the user’s center of gravity passes over the spring system, this shift in load-bearing forces allows the spring to return the stored potential energy to the user in the form of a rapid active lift off and hinge opening. The hinge fully expands to an angle between 30-45 degrees during the swing phase, an angle which allows spring extension while still avoiding toe drag during the late swing phase. Ideal energy return provides the user with partial assistance of plantar flexion, allowing for the development of muscular strength and kinesthetic awareness. Thus, this intervention can both be used as a clinical therapeutic tool and as a full-time orthotic installation.
The spring system requires a base, an attachment face, a compression spring, stiffeners, and fasteners. A compression spring connects the base of the device to the attachment face at the bottom of the HAFO to allow for a mimicking of the dynamics of a natural gait toe-off and swing phase. The spring is selected such that it is prestressed in its open, elevated position to allow for a substantial force distribution across all positions. This arrangement allows for a sharp extension of the system with a limited speed of compression. The rear of the spring system is supported by arms to strengthen the base and more evenly distribute loading forces across the device. The hinge pivot is fixed at the toe, between the base and attachment face, to maximize stability and provide the greatest amount of force return to the user. This pivot determines the range of motion of the hinge, where the resting position lies flush with the walking plane and the maximally opened position is approximately 30-45 degrees in the plantar flexed direction. The base and attachment faces are constructed of thermoplastic, a malleable material that is stiff, light, and inexpensive. The base has a non-skid rubber outsole to ensure maintained contact with the ground. The combination of thermoplastic and rubber results in a firm and durable structure with a lining that ensures non-skid, lightweight, elasticity, and resistance to wear.
We are excited to begin constructing this device over winter break and in the subsequent weeks.
WEEK 16 REPORT
January 14, 2019
This week was our first week back after a long winter break, meaning that we spent a lot of time getting our selves back into the swing of things in terms of our project. We met numerous times this week to outline what the rest of this semester will look like and what steps need to be taken in the short term to achieve our final prototype. Some of the tasks we accomplished this week were:
Secured a date with Keith Smith P.O. to help design our HAFO. We will be meeting with him on 1/28 for a fitting before the final construction of the HAFO.
Made a timeline for the semester, including what we need to get done in these next two weeks to get started on our prototype
Made more detailed drawings and gained deeper understanding to how the internal mechanisms of our device will work
Next week we will be going shopping for parts and constructing a very rough prototype to start with the iteration process.
WEEK 17 REPORT
January 21, 2019
This week our group met to discuss prototyping and make a list of what we need to get in the coming week to start the construction of a viable prototype that we could perform preliminary testing with. We have begun to thing about some of the criteria for our verification and validation report coming up in March, and how we would specifically test for our different design specifications. Additionally, we discussed the questions and specificities of our meeting with Keith on Monday for the construction of our AFO.
WEEK 18 REPORT
January 28, 2019
This week we met with Keith Smith at Children’s hospital and discussed with him our design and the creation of an AFO that we can test with. The conversation was very productive and Keith had a lot of ideas about how to incorporate our device into an AFO, and what kind of parts we could use to construct the main plates on our device. We also discussed the types of plastic that we want to use to construct the AFO and where we might need extra reinforcements on the on the calf sheath (that will connect the device to the AFO). We are still trying to figure out exactly how the attachment to the shoe/AFO will work, but our biggest priority right now is ensuring the device itself achieves the purpose of assisting with plantar flexion. In terms of the mechanics of the device, this week we attempted to construct a rough prototype using cardboard and some struts made out of wood to just get a visual of what the device could look like. From this, we discerned our biggest challenge will be finding struts that attach to the bottom and top plate that have bolts that rotate. Next week we will be working on trying to fix this problem.
WEEK 19 REPORT
February 4, 2019
Although this was a busy week for everyone in our group, we managed to find time to discuss two important topics for our design and brainstorm other ideas.
Will the spring actually facilitate plantar flexion in the way that we want it to?
After making some rough mock prototypes of our design, we are slightly hesitant if the spring is really necessary as the main point of it seemed to just be to slow down the force of the users step back down. Although the spring did help for the plantar flexion, we were thinking of having it face the other way or just straight so it wouldn’t slow down the down step as much.
Where should we thicken the AFO that is being constructed to support the struts of the device?
Part of designing the AFO that we are going to use to test is deciding where we are going to reinforce the plastic on the calf sheath to ensure a good connection with struts on our device. We are also still deciding if we would like to use struts attaching our device to the calf of the AFO in the first place, so this will have to be something that is heavily discussed amongst our group next week.
In the next week, we hope to be able to finalize our design enough to get Sara molded for the AFO and decide exactly what we want the AFO to look like.
WEEK 20 REPORT
February 15, 2019
This week, our group member Sara Arfania presented the Verification and Validation for our project. This presentation focused on key aspects from our Verification and Validation report submitted last week, including proof of concept testing, updates to the project, and protocols to confirm the fulfillment of design specifications. We watched and responded to presentations from the remainder of the senior design class to learn about the other student projects. We also confirmed a meeting with Keith to finalize our HAFO mock-up for use with our prototype. This device will be fitted to Sara Arfania and include the necessary struts and loops to properly attach our foot pad to the bottom of the brace
WEEK 21 REPORT
February 22, 2019
This week we focused on brainstorming ways of testing design specifications for our verification and validation report. We also have been working on our proof-of-concept testing, ensuring that the gas filled spring that we ordered will be able to expand and contract with the right amount of force and in the correct timing as a proper gait cycle. We are working on procuring a force plate that can measure the proper amount of force and give us some data points that will ensure that this could work in our device. Next week we will be primarily working on our verification and validation report and focusing on designing the footplates for the actual device.
WEEK 22 REPORT
March 1, 2019
This week our group worked on completing our Verification and Validation report. We devised many methods of testing our device in accordance with our design specifications, as well as a plan to validate that our design will prove beneficial to patients with a non-typical gait cycle. Additionally, we have been working on finalizing a CAD design to 3D print the plates for the device. We have also been considering constructing the plates from the same material as the hAFO, and having them being molded around the hinge we will be using to hold the plates together rather than screwing the hinge to separately printed plates. This idea is contingent upon the ability of Keith Smith, the orthotist we are working with, to help us determine the feasibility of this idea.
WEEK 25 REPORT
March 22, 2019
This week we met with Keith Smith for the final casting of the hinged AFO that we will be attaching our device to. Once the casting is done and the AFO is made, which should be within the next week, we will be meeting with Keith again to work on the integration of our device to the AFO and the shoe. Additionally, this week we have been doing further research into gait lab procedures that we can use for the testing of our device. We are currently waiting to hear back from our client regarding the use of the newly-constructed gait lab in Children’s Hospital STL. If this route does not work we are hoping to find contacts for the gait lab in Washington University’s physical therapy building to do some testing.
WEEK 26 REPORT
March 29, 2019
This week as we await the completion of our AFO prototype to begin testing, we worked on compiling various parts of the final report. Our report will be primarily composed of how to put together the AFO, as there is little software or circuitry involved in it. We also are finalizing our plans for testing in the gait lab. We are using the help of our client, Courtney Dunn, to determine which procedures would be the most beneficial for us to complete and how to work the equipment associated with them. Next week our prototype will be completed and we will actually be able to start all of the verification testing and complete our report.
WEEK 27 REPORT
April 5, 2019
This week our group has encountered a few setbacks in our prototyping schedule due to issues in scheduling with the construction of our AFO. While this is disappointing, we should now have the prototype by next Tuesday at the latest, and will be able to get within the gait lab that week. While this leaves us with little time to compile the data from the gait lab into the report, we have been working on finishing all other parts of the report before we get the data so that it will be the last thing that we need to compile. This week we have been working on the parts of our report that can be completed without the final prototype, such as extensively describing our parts and drafting the user manual, as well as future directions this project could take.
WEEK 28 REPORT
April 12, 2019
This week we have finally completed our final prototype. We are very excited with how it works so far, and are eager to see what the analysis in the gait lab next Wednesday will be like. Of course, we are realizing ever more the difficulties of effectively testing a device such as this one, which is really more suited for long term testing with actual patients. In addition to our main prototype, we have another semi-prototype of a different design for the spring configuration. In this one, it is simply four springs attached to the bottom plate of the device. We will not be testing this one, but we had extra materials available to us so we wanted to make kind of a ‘comparison device’. Throughout the final stretch of our project, we will be focused on writing the final report and testing. Over and out on our last weekly report! It has been quite a ride.