Editing Prosthesis (section)

===Lower-extremity prosthetics===
[[File:AustralianParalympianOfTheYear 468.JPG|thumb|right|A prosthetic leg worn by [[Ellie Cole]]]]
Lower-extremity prosthetics describes artificially replaced limbs located at the hip level or lower. Concerning all ages Ephraim et al. (2003) found a worldwide estimate of all-cause lower-extremity amputations of 2.0–5.9 per 10,000 inhabitants. For birth prevalence rates of congenital limb deficiency they found an estimate between 3.5 and 7.1 cases per 10,000 births.<ref>{{cite journal|pmid=12736892|year=2003|last1=Ephraim|first1=P. L.|title=Epidemiology of limb loss and congenital limb deficiency: A review of the literature|journal=Archives of Physical Medicine and Rehabilitation|volume=84|issue=5|pages=747–61|last2=Dillingham|first2=T. R.|last3=Sector|first3=M|last4=Pezzin|first4=L. E.|last5=MacKenzie|first5=E. J.|doi=10.1016/S0003-9993(02)04932-8}}</ref>

The two main subcategories of lower extremity prosthetic devices are trans-tibial (any amputation transecting the tibia bone or a congenital anomaly resulting in a tibial deficiency), and trans-femoral (any amputation transecting the femur bone or a congenital anomaly resulting in a femoral deficiency). In the prosthetic industry, a trans-tibial prosthetic leg is often referred to as a "BK" or below the knee prosthesis while the trans-femoral prosthetic leg is often referred to as an "AK" or above the knee prosthesis.

Other, less prevalent lower extremity cases include the following:
# Hip disarticulations&nbsp;– This usually refers to when an amputee or congenitally challenged patient has either an amputation or anomaly at or in close proximity to the hip joint. ''See [[hip replacement]]''
# Knee disarticulations&nbsp;– This usually refers to an amputation through the knee disarticulating the femur from the tibia. ''See [[knee replacement]]''
# Symes&nbsp;– This is an ankle disarticulation while preserving the heel pad.

====Socket====
The socket serves as an interface between the residuum and the prosthesis, ideally allowing comfortable weight-bearing, movement control and [[proprioception]].<ref>{{cite journal|pmid=11392649|year=2001|last1=Mak|first1=A. F.|title=State-of-the-art research in lower-limb prosthetic biomechanics-socket interface: A review|journal=Journal of Rehabilitation Research and Development|volume=38|issue=2|pages=161–74|last2=Zhang|first2=M|last3=Boone|first3=D. A.}}</ref> Socket problems, such as discomfort and skin breakdown, are rated among the most important issues faced by lower-limb amputees.<ref>{{cite journal |last1=Legro |first1=MW |last2=Reiber |first2=G |last3=del Aguila |first3=M |last4=Ajax |first4=MJ |last5=Boone |first5=DA |last6=Larsen |first6=JA |last7=Smith |first7=DG |last8=Sangeorzan |first8=B |title=Issues of importance reported by persons with lower limb amputations and prostheses. |journal=Journal of Rehabilitation Research and Development |date=July 1999 |volume=36 |issue=3 |pages=155–63 |pmid=10659798 }}</ref>

====Shank and connectors====
This part creates distance and support between the knee-joint and the foot (in case of an upper-leg prosthesis) or between the socket and the foot. The type of connectors that are used between the shank and the knee/foot determines whether the prosthesis is modular or not. Modular means that the angle and the displacement of the foot in respect to the socket can be changed after fitting. In developing countries prosthesis mostly are non-modular, in order to reduce cost. When considering children modularity of angle and height is important because of their average growth of 1.9&nbsp;cm annually.<ref name="ReferenceA"/>

====Foot====
Providing contact to the ground, the foot provides shock absorption and stability during stance.<ref>{{cite journal|doi=10.1097/00008526-200510001-00007|title=Perspectives on How and Why Feet are Prescribed|journal=Journal of Prosthetics and Orthotics|volume=17|pages=S18–S22|year=2005|last1=Stark|first1=Gerald}}</ref> Additionally it influences gait biomechanics by its shape and stiffness. This is because the trajectory of the center of pressure (COP) and the angle of the ground reaction forces is determined by the shape and stiffness of the foot and needs to match the subject's build in order to produce a normal gait pattern.<ref>{{cite journal|doi=10.1016/0966-6362(93)90038-3|title=Trajectory of the body COG and COP during initiation and termination of gait|journal=Gait & Posture|volume=1|pages=9–22|year=1993|last1=Jian|first1=Yuancheng|last2=Winter|first2=DA|last3=Ishac|first3=MG|last4=Gilchrist|first4=L}}</ref> Andrysek (2010) found 16 different types of feet, with greatly varying results concerning durability and biomechanics. The main problem found in current feet is durability, endurance ranging from 16 to 32 months<ref name="ReferenceB">{{cite journal |last1=Andrysek |first1=Jan |title=Lower-limb prosthetic technologies in the developing world: A review of literature from 1994–2010 |journal=Prosthetics and Orthotics International |date=December 2010 |volume=34 |issue=4 |pages=378–398 |doi=10.3109/03093646.2010.520060 |pmid=21083505 |s2cid=27233705 }}</ref> These results are for adults and will probably be worse for children due to higher activity levels and scale effects. Evidence comparing different types of feet and ankle prosthetic devices is not strong enough to determine if one mechanism of ankle/foot is superior to another.<ref name=":2">{{cite journal |last1=Hofstad |first1=Cheriel J |last2=van der Linde |first2=Harmen |last3=van Limbeek |first3=Jacques |last4=Postema |first4=Klaas |title=Prescription of prosthetic ankle-foot mechanisms after lower limb amputation |journal=Cochrane Database of Systematic Reviews |issue=1 |pages=CD003978 |date=26 January 2004 |volume=2010 |doi=10.1002/14651858.CD003978.pub2 |pmid=14974050 |pmc=8762647 |url=https://pure.rug.nl/ws/files/67438636/Hofstad_et_al_2004_Cochrane_Database_of_Systematic_Reviews.pdf }}</ref> When deciding on a device, the cost of the device, a person's functional need, and the availability of a particular device should be considered.<ref name=":2" />

====Knee joint====
{{Main article|Knee replacement}}
In case of a trans-femoral (above knee) amputation, there also is a need for a complex connector providing articulation, allowing flexion during swing-phase but not during stance. As its purpose is to replace the knee, the prosthetic knee joint is the most critical component of the prosthesis for trans-femoral amputees. The function of the good prosthetic knee joint is to mimic the function of the normal knee, such as providing structural support and stability during stance phase but able to flex in a controllable manner during swing phase. Hence it allows users to have a smooth and energy efficient gait and minimize the impact of amputation.<ref>{{Cite journal|last1=Andrysek|first1=Jan|last2=Naumann|first2=Stephen|last3=Cleghorn|first3=William L.|date=December 2004|title=Design characteristics of pediatric prosthetic knees|url=https://pubmed.ncbi.nlm.nih.gov/15614992/|journal=IEEE Transactions on Neural Systems and Rehabilitation Engineering |volume=12|issue=4|pages=369–378|doi=10.1109/TNSRE.2004.838444|issn=1534-4320|pmid=15614992|s2cid=1860735}}</ref> The prosthetic knee is connected to the prosthetic foot by the shank, which is usually made of an aluminum or graphite tube.

One of the most important aspect of a prosthetic knee joint would be its stance-phase control mechanism. The function of stance-phase control is to prevent the leg from buckling when the limb is loaded during weight acceptance. This ensures the stability of the knee in order to support the single limb support task of stance phase and provides a smooth transition to the swing phase. Stance phase control can be achieved in several ways including the mechanical locks,<ref>{{Cite thesis|title=Evaluation and Design of a Globally Applicable Rear-locking Prosthetic Knee Mechanism|url=https://tspace.library.utoronto.ca/handle/1807/33575|date=2012-11-27|degree=Thesis|language=en-ca|first=Dominik|last=Wyss}}</ref> relative alignment of prosthetic components,<ref name=":5">R. Stewart and A. Staros, "Selection and application of knee mechanisms," Bulletin of Prosthetics Research, vol. 18, pp. 90-158, 1972.</ref> weight activated friction control,<ref name=":5" /> and polycentric mechanisms.<ref>M. Greene, "Four bar linkage knee analysis," Prosthetics and Orthotics International, vol. 37, pp. 15-24, 1983.</ref>

=====Microprocessor control=====
To mimic the knee's functionality during gait, microprocessor-controlled knee joints have been developed that control the flexion of the knee. Some examples are [[Otto Bock]]'s C-leg, introduced in 1997, [[Ossur]]'s Rheo Knee, released in 2005, the Power Knee by Ossur, introduced in 2006, the Plié Knee from Freedom Innovations and DAW Industries' Self Learning Knee (SLK).<ref>[http://www.daw-usa.com/Pages/SLK3.html "The SLK, The Self-Learning Knee"] {{Webarchive|url=https://web.archive.org/web/20120425081600/http://www.daw-usa.com/Pages/SLK3.html |date=2012-04-25 }}, DAW Industries. Retrieved 16 March 2008.</ref>

The idea was originally developed by Kelly James, a Canadian engineer, at the [[University of Alberta]].<ref>{{Cite news|url= https://www.nytimes.com/2005/06/20/health/menshealth/20marrbox.html |title = Titanium and Sensors Replace Ahab's Peg Leg |access-date=2008-10-30 |work= The New York Times |date= 2005-06-20 | first=Michel | last=Marriott}}</ref>

A microprocessor is used to interpret and analyze signals from knee-angle sensors and moment sensors. The microprocessor receives signals from its sensors to determine the type of motion being employed by the amputee. Most microprocessor controlled knee-joints are powered by a battery housed inside the prosthesis.

The sensory signals computed by the microprocessor are used to control the resistance generated by [[hydraulic cylinders]] in the knee-joint. Small valves control the amount of [[hydraulic fluid]] that can pass into and out of the cylinder, thus regulating the extension and compression of a piston connected to the upper section of the knee.<ref name=PikeAlvin>Pike, Alvin (May/June 1999). "The New High Tech Prostheses". InMotion Magazine 9 (3)</ref>

The main advantage of a microprocessor-controlled prosthesis is a closer approximation to an amputee's natural gait. Some allow amputees to walk near walking speed or run. Variations in speed are also possible and are taken into account by sensors and communicated to the microprocessor, which adjusts to these changes accordingly. It also enables the amputees to walk downstairs with a step-over-step approach, rather than the one step at a time approach used with mechanical knees.<ref name=MartinCraigW>Martin, Craig W. (November 2003) [http://www.ibrarian.net/navon/paper/Evidence_Based_Practice_Group__EBPG_.pdf?paperid=2575568 "Otto Bock C-leg: A review of its effectiveness"] {{Webarchive|url=https://web.archive.org/web/20161228231356/http://www.ibrarian.net/navon/paper/Evidence_Based_Practice_Group__EBPG_.pdf?paperid=2575568 |date=2016-12-28 }}. WCB Evidence Based Group</ref> There is some research suggesting that people with microprocessor-controlled prostheses report greater satisfaction and improvement in functionality, residual limb health, and safety.<ref name="Kannenberg 2014 1469–1496">{{cite journal |last1=Kannenberg |first1=Andreas |last2=Zacharias |first2=Britta |last3=Pröbsting |first3=Eva |title=Benefits of microprocessor-controlled prosthetic knees to limited community ambulators: Systematic review |journal=Journal of Rehabilitation Research and Development |date=2014 |volume=51 |issue=10 |pages=1469–1496 |doi=10.1682/JRRD.2014.05.0118 |pmid=25856664 |s2cid=5942534 }}</ref> People may be able to perform everyday activities at greater speeds, even while multitasking, and reduce their risk of falls.<ref name="Kannenberg 2014 1469–1496"/>

However, some have some significant drawbacks that impair its use. They can be susceptible to water damage and thus great care must be taken to ensure that the prosthesis remains dry.<ref>{{cite journal |last1=Highsmith |first1=M. Jason |last2=Kahle |first2=Jason T. |last3=Bongiorni |first3=Dennis R. |last4=Sutton |first4=Bryce S. |last5=Groer |first5=Shirley |last6=Kaufman |first6=Kenton R. |title=Safety, Energy Efficiency, and Cost Efficacy of the C-Leg for Transfemoral Amputees: A Review of the Literature |journal=Prosthetics and Orthotics International |date=December 2010 |volume=34 |issue=4 |pages=362–377 |doi=10.3109/03093646.2010.520054 |pmid=20969495 |s2cid=23608311 }}</ref>