Below Knee Prosthetic Leg Designs

Lytra Prosthetic Shower Leg By Harry Teng

Industrial designer Harry Teng introduces Lytra, the one and only affordable prosthetic leg that allows below-the-knee amputees to take showers safely and maintain residual limb hygiene. Designed with the goal of pushing the concept to a market-ready product, Lytra is not only a structure to overcome some physical obstacles, but also a body extension that has emotional attachments for amputees to rely on every day.

all images courtesy of Harry Teng

Effect Of Prosthesis Alignment And Adjustment On Gait

Prosthesis alignment and adjustment as a way to maximize patientscomfort and gait performance have been investigated and established these issues constitute a necessary element of daily work in prosthetic facilities.Detailed instructions have been developed for assessing gait in each of the stridephases and for corresponding measures to be taken by a prosthetist to benefit apatient . Czerniecki developed asummary of procedures and suggested considering the residuum-socket interface as avirtual joint that needs to be stabilized by the external moments. Since momentsfrom the socket to the residuum in all three planes depend on lever arms of groundreactions, proper alignment may minimize such moments and consequently reduce normaland shear stresses on the residuum. To illustrate that approach, we generated Table A, where gait deviations frequentlyobserved in transtibial amputees are presented against possible sources ofmalalignment.

Johns Hopkins Comprehensive Amputee Rehabilitation Program

Having the support of a dedicated team of experts is essential when recovering from the amputation of a limb. At Johns Hopkins, our team of physiatrists, orthotists, prosthetists, physical and occupational therapists, rehabilitation psychologists and other specialists works together to create your custom rehabilitation plan.

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Prosthetic Leg Technology Is Always Evolving

There are always new developments in prosthetic limb technology, such asmicroprocessor-driven and activity-specific components.

• Microprocessor joints feature computer chips and sensors to provide a more natural gait. They may even have different modes for walking on flat surfaces or up and down the stairs.
• There are also specialized prosthetic legs for different activities, such as running, showering or swimming, which you can switch to as needed. In some cases, your everyday prosthetic leg can be modified by your prosthetist to serve different purposes.
• Osseointegration surgery is another option. This procedure involves the insertion of a metal implant directly into the bone, so there is no need for a socket. The prosthetic leg then attaches directly to that implant. While this procedure is not right for everyone and is still under study, it can provide improved range of motion and sensory perception.

Its important to remember that youre not alone in navigating the manydifferent prosthetic leg options. Your care team will help you weigh thepros and cons of each and decide on the ideal prosthetic leg that matchesyour lifestyle.

The Effects Of Prosthetic Ankle Dorsiexion And Energy Return On Below

a r t i c l e i n f o a b s t r a c t

Fig. 1. Foot conditions: solid ankle, SA stiff forward-facing ankle, FA compliant FA stiff reverse-facing ankle, RA and compliant RA. The pylon attached directly tothe Seattle Lightfoot2 for the SA condition, whereas the ankle was attached between the pylon and the Seattle Lightfoot2 for the other four conditions. 300 J.D. Ventura et al. / Clinical Biomechanics 26 298303

Fig. 3. Joint moments of the intact and residual leg hip, knee and ankle over stance. Noted are the peak hip joint extensor moment , hip joint exor moment , knee joint extensor moment in early stance , knee joint exor moment and knee joint extensor moment in late stance . Statistically signicant differences from SAFig. 2. Intact and residual leg vertical and anterior/posterior ground reaction forces are noted for stiff FA , compliant FA , stiff RA and compliant RA . over stance and A/P GRF impulses during braking and propulsion. Noted are peakvertical GRFs in early stance and late stance . Statistically signicant differences fromSA are noted for stiff FA , compliant FA , stiff RA and compliant RA . 3.3. Joint moments and powers

Table 1Average ankle properties: peak dorsiexion, energy storage and return in early stance, and energy storage and return in late stance. denotes a signicant difference from SA.

Peak dorsiexion Energy storage – early stance Energy return – early stance Energy storage – late stance Energy return – late stance

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Donning And Doffing Of Liners And Sockets

Donning a prosthesis refers to the application of a prosthetic device, doffing refers to the act of removing a prosthetic device.

There are many different types of prostheses available and the process of donning and doffing each is different. You will individually need to become familiar with the types of prosthesis that you use but these videos below provide some insight into donning and doffing socks, liners and prosthetics:

Influence Of Moment Of Resistance In Prosthetic Ankle On Gait

The moment is defined as a rotational potential of the forcesacting on a joint. During balance, a resultant moment Mrof forces causing rotation at the angle equals the resultant momentMa of forces providing resistance to that rotation. In motion,Mr is greater than Ma,and the exact difference is given by Newtons second law for rotation byEquation , whereI is the moment of inertia of the angulating link, and

Resultant moment Mr of forces causingrotation at the angle and resultant momentMa of forces providing resistance to thatrotation. Reactions in joint are not accountable since their lever arms relativeto the joint equal zero.

Muscles affecting a joints articulation as well as the force ofgravity may contribute either to Ma or toMr depending on the body configuration duringdifferent phases of locomotion. For example, during most of the stance phase, footplantarflexors provide resistance to dorsiflexionrotation in the ankle after heel rise they cause active plantarflexion. The same is true for body weightmg and ground reactions vectorR since these forces change orientationrelative to the joints center from anterior to posterior several timesduring the stride cycle .

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Not Everyone Benefits From A Prosthetic Leg

While many people with limb loss do well with their prosthetic legs, noteveryone is a good candidate for a leg prosthesis. A few questions you maywant to discuss with your doctor before opting for a prosthetic leginclude:

• Is there enough soft tissue to cushion the remaining bone?
• How much pain are you in?
• What is the condition of the skin on the limb?
• How much range of motion does the residual limb have?
• Is the other leg healthy?
• What was your activity level before the amputation?
• What are your mobility goals?

The type of amputation can also affect yourdecision. Its generally easier to use a below-the-knee prosthetic leg thanan above-the-knee prosthesis. If the knee joint is intact, the prostheticleg takes much less effort to move and allows for more mobility, explainsKeszler.

The reason behind the amputation is also a factor, as it may impact thehealth of the residual limb. Your physical health and lifestyle are alsoimportant to consider. If you were not very active and lost your leg due toperipheral vascular diseaseordiabetes, for example, you will struggle more with a prosthesis than someone whowas extremely active but lost a limb in a car accident.

When it comes to amputation, each person is unique. The decision to moveforward with a prosthesis should be a collaborative one between you andyour doctor.

To get the right type and fit, its important to work closely with your prosthetist a relationship you might have for life.

Mary Keszler, M.D.

This Modular Prosthetic Shower Leg Facilitates Easy Cleaning Of Residue Limb

Below the knee amputees have to jockey their way around even for normal tasks, making things difficult in the daily grind. Taking a shower is one of them, and such disabled individuals either have to skip taking a shower completely or crawl their way to the bathroom, since normal prosthetics cannot be exposed to water due to their metal components.

Even if they do manage to take a shower with special aids such as a walker, safety grip, shower chair, or shower leg properly washing the residual leg is still a problem due to their inherent design. One can say a shower leg is still better, but not every disabled person can spare $4000 for just one function alone. This can lead to bacterial infections developing in the limb which can in the worst-case scenario can lead to further amputation. Just imagine the situation for the elderly who have even more constraints in movement as compared to young lads.

Designer: Harry Teng

The innovative prosthetic leg is made out of medical-grade polypropylene material called Proteus Sheet. All the inherent components of Lytra are interchangeable so that they can be replaced easily in case theres damage or deformation. The socket of the prosthetic comes in XS, S, M, L and XL sizes to suit users of every leg type. Theres a silicone gel bottom for soft and comfy support for the limb resting on it. These sockets are interchangeable for hygiene purposes to prevent any infection.

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Your New Balance In Life

The ankle and foot are key to providing stability and balance to your body. While amputations can be life-altering, and often thought of as an end, at HOPE we see below the knee amputations in Kansas City as a new beginning to enhance your life. Maximizing your ability to walk with comfort and ease.

Moment Of Resistance In The Prosthetic Knee

To prevent collapsing during weight acceptance, prosthetic knee mechanismsusually are designed without the option of flexion in early stance . However, a desireto provide the stance flexion seen in normal gait has resulted in three recent kneemechanisms of that type: the Otto Bock 3R60 EBS Kneea, the Blatchford Endoliteb and the Total Kneec.

While new knee mechanisms demonstrate up to 15 degrees of flexion under theload equivalent to body weight in mechanical tests, none show a stance-knee anglegreater than 5 degrees during actual amputee gait . A combination of two reasons may explain this.

First, these knees have a concave pattern moment of resistanceversus stance-knee angle similar to commercially available feet , which means initiation ofknee flexion requires an excessive load, which translates to excessive pressure onthe residuum. To avoid pain associated with such an excessive pressure, amputees areadvised not to execute the full range of motion technically possible with theadvanced prosthetic knee joints.

Synergetic range of motion in knee with free andrigid ankle.

A direct request for the design of prosthetic foot/ankle units with truebiological plantarflexion within the ankle mechanism for transfemoral prostheses wasjustified since such a feature wouldprovide better absorption of the shock and moment generated at heel strike, therebydecreasing potential knee instability.

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Freds Legs: Sleeveart Prosthetic Sleeve Covers

• Highest rating: 3
• Lowest rating: 3
• Descriptions: SleeveArt prosthetic covers for artificial limbs and laminating sleeves for orthotic devices and sockets give your brace or limb a unique or custom look
• More : SleeveArt prosthetic covers for artificial limbs and laminating sleeves for orthotic devices and sockets give your brace or limb a unique or custom look
• https://fredslegs.com/

Biomechanical Principles Of Prosthesis And Gait In Prosthetic Leg

The gait cycle which consists of two stages will also be termed as walking cycle. Initial contact is the first step in the starting point and the end point in every gait cycle. A single gait cycle has two phases. The stance phase and the swing phase. The stance phase is the initial step in which the foot contact starts followed by other steps in the ground. The stance phases contribute about 60% of the gait cycle and the swing phase contributes about 40% of the gait cycle. The swing denotes the single leg support in which the foot is off the ground.

The pattern of gait in subjects with prosthesis will present an altered gait pattern. Here the foot contact on the ground and the weight distribution on the foot is the key factor to be noted. The foot contact will occur on the heel in such a way the walking cycle will be as natural as possible. In this situation the sole of the foot will contact the ground and the weight is transmitted to the foot. Thus, the selection of foot component and the knee joint must be proper. This is because this will have an influence on the subjects gait when he turns on to the next phase .

During swing phase, the knee function is so important so that the mobility on the knee joint performing both flexion and extension facilitating the foot transition from plantar flexion to dorsiflexion i.e toe elevation. This will prevent the subject from stumbling and subsequent fall.

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Post Amputation Process And Prosthetic Evaluation

Pre- prosthetic training

Prosthetic Evaluation

Initial evaluation to determine if a patient is a candidate for a lower limb prosthesis should include the following assessment of the patients history:

The patient must also be physically and mentally evaluated to determine the appropriate prosthetic prescription, complete assessment includes:

How To Choose Below Knee Prosthetic Leg: The Buying Guide

How do you choose the below knee prosthetic leg? You must consider many things, such as the brand name, price, and product quality. In addition, you should also consider whether it is suitable for your needs or not.

So how do you choose the right below knee prosthetic leg? Here are some tips that you can use to help you find a good product:

What you Should Keep in Mind When Buying below knee prosthetic leg

When shopping for a below knee prosthetic leg, there are several things to consider. You need to think about the quality of the product, the price, and even how much it will benefit your life. However, you also need to keep these factors in mind:

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A Model Of The Residuum

Kinematic and kinetic components of the model are illustrated in Figures 68. The model is a planar open chain of six weightless rods: two feet oflengths lf1 and lf2 twoshanks ls1 and ls2 and twothighs lt1 and lt2. Anglesbetween these elements and the vertical are fi,si and ti , respectively .

Normal and prosthetic gait synergies.

It is assumed that center of mass is located at the central joint,simulating projection of both hip joints. Step length L and heightH of the COM are given by Equations :

LHlllHlll

There are certain anthropomorphic restraints on the values of the 14parameters. When 11 of them are specified, the other three can be calculated fromEquations . Feet, shanks andthighs are recommended to be paired-equal length and should not be consideredvariables, but constants, which reduces the number of undetermined parameters tofive. Additionally, two constraints were derived based on gait analysis dataregarding stance events.

Dynamic effect of the moment of resistanceMa in the ankle of the foreleg on the propulsivemoment Mp in the ankle of the contralateral leg.

The effect of the resistive moment Ma =F×r onresiduum-socket interface in transtibial amputees is simulated inFigure 8, where couple forces±F are applied from the socket to the residuum. Theforces ±F provide normal stresses on the residual limb inaddition to shear stresses derived from the axial load as explained by Pearson.

Total Surface Bearing Sockets

• TSB sockets uniformly distribute weight over the entire residual limb which therefore delivers a minimal skin pressure.
• TSB sockets are volume matched to the residual limb with 100% surface contact during the gait cycle.
• Successful fitting of a TSB socket requires good control of the soft tissues, minimised pressure peaks and distribution of load over the maximum surface area available.

Advantages and Indications

Disadvantages and Contraindications

Transversal view shows the differences between the internal shapes of PTB SC v SSS sockets.

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