Dog Can Walk Again Thanks To 3D Printing

Check this out! Dog Can Walk Again Thanks To 3D Printing

"Another day, another animal given a new lease on life thanks to 3D printing. This time it’s Derby, a dog born with deformed legs who, with the help of some folks at 3DSystems, now runs alongside his owners with gleeful abandon. Derby’s front legs have been augmented with two blade-like attachments that Who’s-a-Good-Boy uses to run and scamper."

Bloopers: "Weight-ing" for the shanks to break! Cinder block fun times

Watching a cinder block fall in "de-feet"

“Metal-ing” with the weight distribution!

This lovely balancing act fell with a BANG not a minute after these pictures were taken.

Research Update (12/8/14): New Designs (some, even printed!)

Original Bio-Mimic Pylon (Left View)

Original Bio-Mimic Pylon (Angled View)

Secondary Bio-Mimic Pylon (Angled View)

Secondary Bio-Mimic Pylon (Left View)

Doubled Banded
Bio-Mimic Pylon (Left View)

Doubled Banded
Bio-Mimic Pylon (Angled View)

The intent of these designs is to mimic the natural flow of the leg and hopefully spread the pressure out better than a basic straight design. After consulting with my supervisor on the earlier bowed design (this design will not be printed. After designing and seeing the first set of parts print, it became apparent that this design is too bulky, both in weight and size, for practical application), he suggested designing a limb in this direction. Inspiration came from images on this site.

The series of events since the last post occurred chronologically as follows: 

• The first set of pylons (already posted) were designed,
• the straight elliptic pylon was printed, the first true bio-mimic pylon was designed,
• the bio-mimic pylon was printed at a percentage so as to copy the size of the other pylon (it was overshot and the bio-mimic pylon was slightly smaller),
• it was realized that the bows of the original bio-mimic pylon are on the wrong the axis of the ellipse (perpendicular to the minor axis rather than the major, which matches natural design better) and the pylon was not useful do to my accidentally including an ankle component, which is made superfluous by foot attachments,
• the second bio-mimic pylon was designed with the bow perpendicular to the major axis without the intent of production (this design was made primarily for cataloguing, creating a template for future designs on which to build, and visualization),
• the double banded pylon was designed,
• the first produced pylon was qualitatively evaluated under impact; it was determined an elliptic straight pylon of 16cm at 10% in-fill can withstand impact up to 3500-4000 N of pressure for showing serious damage,
• the double banded pylon and the elliptic straight pylon were printed at 10% in-fill with percentages that would produce pylons of approximately 20cm,
• the double banded pylon experienced a printing failure and was reprinted at 20% in-fill.

As you can see from the link and the first four pictures, I got lost in designing and forgot about actual functionality of the product. The first two bio-mimic legs are pretty much a waste due to them extending to ball of the ankle. This error was considered when designing the double-banded pylon.

The reasoning behind these designs (and some sketches for future designs) was the natural design of human legs externally (they match the outlines of the calf muscle, which may result in greater aesthetic appeal) and the structures of the tibia and fibula with respect to one another. The latter is why the central column in all three designs does not have a static circumference; rather, it's thin in the middle and largest at the top and base.

Qualitatively determined by just holding the two existing parts, is that the double banded pylon (20%) is much stronger than the elliptic straight pylon (10%). It is hard to judge whether this is solely due to the difference in in-fill (I am going to have the straight pylon printed with 20% in-fill next) or it could be due to either the presence of banded or a central column with dynamic radii.

The next step, which will occur before Thursday, is to test the pylons by applying sustained pressure (rather than impact). This will by done resting cinder blocks (weighing approximately 160 N each, which is approximately 36 lbs) and other modes of weight while the pylon is fixed to a force plate. The force plate will connected to a data logger, which will record all of this. Weight will be applied to the pylon until it shows signs of damage.

Establishing the Problem: Rationale

There is unmet need for transtibial prostheses for persons <18 years of age that are capable of growing with the minor; that is, the prosthesis is either easily replaceable or adjustable beyond what is currently provided, which must be replaced every 1 to 2 years when the child grows beyond the prosthesis’ range of adjustment or wears out the limb with continuous stress. A child will need frequent replacement of a transtibial prosthesis for two primary reasons: growth and activity.

According to the CDC and researchers at Worcester Polytechnic Institute, children between ages 2 and 14 may grow 5-10 cm per year. Although conventional transtibial prostheses are capable of adjustment--endoskeletal shanks can be adjusted by changing the internal piping, exoskeletal shanks can be adjusted incrementally with the addition of shims by a prosthetist, and shoe insert may be added for both types of shanks--these adjustments have their limitations, and the child will require a new prosthesis given how rapidly they grow, both in height and weight.

People under 18 years of age also tend to be very active, putting more strain on their joints and requiring a higher range of motion. With continuous use, either sustained moderate pressure (i.e. walking, standing, etc.) or intermittent pressure (i.e. jumping, running, etc.), the prosthesis will exhibit a weakened shank, wear on movable components, and a less aesthetically pleasing external finish.

Frequent replacement of the prostheses should not be a problem; replacements do exist for all four components of a below-knee prosthesis (ankle-foot assemblies, shanks, below-knee sockets, below-knee prosthetic suspensions), but patients and families face financial restrictions in most cases. Prostheses are expensive (usually upward of $5,000) and frequent replacement is burdensome. Patients who require frequent replacements often deal with restrictions from their primary third-party payer. In some cases, children are denied financial reimbursement from insurers and must decline a prosthesis that their families can’t afford.

Initials Concept Designs (printing soon)

First designs! These are going to be the first three designs printed. The next one to come will probably be something simulating the natural tibia-fibula design.

Adult Elliptic Pylon

Adult Elliptic Pylon
(with notes)

Adult Circular Pylon

Adult Circular Pylon
(with notes)

Adult Circular Straight Pylon
with Bows

Adult Circular Straight Pylon
with Bows (with notes)

Adult Circular Straight Pylon with Bows (cross section)

Open Hand Projects

If you're interested in prosthetic hand research, check out these articles:

http://www.eng.yale.edu/grablab/openhand/
http://www.openhandproject.org/
https://www.indiegogo.com/projects/the-open-hand-project-a-low-cost-robotic-hand

Cool Article: Kids outfitted with new hands made on 3-D printers

Within the past year, a child, Griffin Matuszek, was fitted with a function 3-D printed hand!
Read the article to find out more. This serves as proof that 3-D printing has effectively helped children with limb deficiencies. However, there is a big difference between a hand and a leg. While a hand is more mechanically intensive, a leg is under more physical stress due to weight. A hand is a good place to start, but further research must go into the limitations of 3-D material.

Also check out this article published by Fox News to learn more about Griffin Matuszek's story. This article goes a bit more into the potential for 3-D products in the medical industries, both the pros and cons. Check it out!

Article Review: Limb Prosthetics Services and Devices: Critical Unmet Need: Market Analysis

This article reviews the current--the year of publication is unknown, although the text indicates publication between 2009 and 2013--state of limb prosthetics services and devices in the context of the United States market: "The scope of this market analysis focuses on limb prosthetics in the United States." However, the study openly acknowledges that data are varying and hard to access, if accessible at all, so there are limitations on the study. 

"When a person becomes a limb amputee, he or she is faced with staggering emotional and financial lifestyle changes." There is a growing, "demand for restoring mobility and independence from amputees," and a growing "consumer base of amputees drives the market with demands for improvement in quality of life and innovation will address quality of life needs." However, this growing demand and "period of rapid technological advances in lower limb prostheses" has resulted in relatively constant satisfaction polls ("overall amputee satisfaction with the prosthesis has remained relatively constant, varying between 70-75% of those polled.") and an "estimated reduction in funding for amputee care of 20% compared to prior decades."

The economic downturn in 2009 "has exasperated the rate of commercial R&D for limb prosthetics innovation. All markets have been hit hard. Third party payers are more restrictive." Third party payers include Medicare, Medicaid, the U.S. Department of Veterans Affairs, and private third-party insurers. For children, this is reduced to just Medicaid--"a health insurance program jointly funded by federal and state governments providing health insurance coverage for certain persons in financial need, regardless of age"--and more importantly, private insurers. However, "Yearly third party health insurance caps on prosthetic services range from $500 to $ 3000 and lifetime restrictions range from $10,000 to one prosthetic device during a person's lifetime (from birth to death)."

These financial caps are insufficient to purchase anything but "lower priced products that are less effective." A below-knee prosthetic ranging from $5,000 to $7,000, "a patient can get a serviceable below-the-knee prosthesis that allows the user to stand and walk on level ground. By contrast, a $10,000 device will allow the person to become a "community walker," able to go up and down stairs and to traverse uneven terrain. A prosthetic leg in the $12,000 to $15,000 price range will facilitate running and functioning at a level nearly indistinguishable from someone with two legs."

Prices for remain high despite third-party payer caps and research and development for prosthetics designs. This pricing is largely due to prostheses not being produceable in mass quantities; "If one device could serve everyone, then prosthetics could be mass produced and costs reduced.  But limb prosthetics are produced in relatively small numbers and made of custom materials, with a variety of componentry. Sizes are different so each model may have six or eight variations depending on the needs of each patient."

With children, the greatest concern is the rate at which they grow and how to accommodate a child with a constantly will fitted prosthetic; "... children need more frequent replacements to keep pace with their growth. A child of twelve may grow four inches and gain twenty pounds in a year. A new limb prosthesis is needed." With financial caps set at $10,000, it is unlikely for a child to receive the devices they need to accommodate their growth. Most shockingly, "Some insurers also will readily reimburse for an amputation and secondary complications (including further amputation) stemming from inactivity, but they will limit or refuse to cover a prostheses replacement for an active amputee or a growing child," due to active amputees putting a lot of wear on the devices, which insurers are unwilling to reimburse, and children requiring many inevitable replacements.

"Diabetes and peripheral vascular diseases rank as the number one cause of amputation in the United States, where an average 185,000 amputations are performed annually, thus increasing the consumer base and presenting opportunities for service providers." 82% of those 185,000 amputations surgeries were due to Peripheral Vascular Disease and Diabetes.

Although "there is a direct correlation between age and the onset of diabetes and vascular disease, which are the leading causes of amputations," other causes of amputation include congenital disease and trauma (accidents and war-related ones specifically). Lawnmower accidents are exceedingly common in children; "Approximately 8,900 children receive amputations each year due to lawn mower accidents," which makes up approximately 4.8% of amputation surgeries in the United States. When focusing on children, it is also important to consider congenital diseases; “Birth defects result in a life long need for prosthetic devices… Every day in the United States, children are born with missing limbs, and teenagers suffer amputations as a result of accidents or cancer." As of 1996, 70,000 persons <18 years of age were living with limb loss.

A transtibial prosthetic, "is an artificial limb that replaces a leg missing below the knee. Transtibial amputees are usually able to regain normal movement more readily than someone with a transfemoral amputation [a leg missing above the knee], due in large part to retaining the knee, which allows for easier movement." If you would like to learn the details about either, click on this for details on below-knee amputations and below-knee prosthetics.

To read the article, follow this link:
http://www.nist.gov/tip/wp/pswp/upload/239_limb_prosthetics_services_devices.pdf

Cool article about 3D printing and prosthetics

I stumbled upon this article while researching; I don't know how credible the source is, but it's still a cool and relevant article. Check it out!  The Role Of 3D Printing In The Design And Manufacture Of Prosthetic Devices

Article Review: Traumatic amputations in children and adolescent, A.J. Roche, K. Selvarajah

Before addressing "the problem," it is necessary to establish that there even is a problem. The data reported in "Traumatic amputations in children and adolescents" by A. J. Roche and K. Selvarajah provides evidence that there may be patterns in adolescent amputation injury type.

The focus of their cohort study was, "to report the demographics of severe trauma leading to amputation in an urban United Kingdom paediatric population, and to compare [their] cohort with similar groups in other units." They collected data from a center that "assesses and treats all patients within a catchment area of 1 to 1.3 million people [along with referrals from other regions] who have been referred from local hospitals with loss of digits or limbs or for advice on the management of prostheses." Roche and Selvarajah limited their study population to those, "having had an amputation as a result of trauma from any mechanism,... ≤ 18 years of age when injured."

Roche and Selvarajah were able to collect the details on 112 patients; however, only data for 93 patients, ranging from 1930 to 2011, were usable. 83 of those patients had lower -limb amputations, 48 of which were below knee.

In the geographic area they were studying, "the pedestrians injured by buses all resulted in lower-limb amputations, as did almost all the other road injuries;" bus injuries accounted for 32% of cases, and total "accidents on road accounted for 63% of all injuries."

These data suggest that, at least in the UK, automobile related injury is the dominant injury type and that lower-limb amputation is the dominant amputation type, with lower knee being the most common lower-limb amputation subtype. However, Roche and Selvarajah outline the differences between UK-based studies and US-based studies; "Paediatric amputation amputations have been studied more closely in the United States, where it seems that they are more frequent. Loder performed a demographic study similar to ours [in the United States]... and showed some contrasting results... Over half were caused by a combination of lawnmowers (29%) and farming machinery (24%), and only 16% followed road traffic accidents."

In addition to the difference in injury-cause types, the study also suggested injury resulting in amputation is less financially burdensome in the UK, although it, "has been shown to have significant financial burdens in other countries," and this might be do to the infrequency of injury resulting in amputation in the United Kingdom.


Citations to follow up on include:

Trautwein LC, Smith DG, Rivara FP. Pediatric amputation injuries: etiology, cost,
and outcome. J Trauma 1996;41:831-8.

Loder RT. Demographics of traumatic amputations in children: implications for prevention strategies. J Bone Joint Surg [Am] 2004; 86-A:923-8.

Conner KA, McKenzie LB, Xiang H, Smith GA. Pediatric traumatic amputations
and hospital resource utilization in the United States, 2003. J Trauma 2010;68:131-7.

Conner KA, Williams LE, McKenzie LB, et al. Pediatric pedestrian injuries and
associated hospital resource utilization in the United States, 2003. J Trauma
2010;68:1406-12.

Krebs DE, Fishman S. Characteristics of the child amputee population. J Pediatr
Orthop 1984;4:89-95

To read the article, follow this link: http://www.ncbi.nlm.nih.gov/pubmed/21464491 or http://www.boneandjoint.org.uk/highwire/filestream/17823/field_highwire_article_pdf/0/507.full-text.pdf