ALPS PROSTRIDE PROSTHETIC KNEE COMPARATIVE STUDY

A comparative study on a 59-year-old subject with over 25 years of prosthetic use, evaluating electronic knee joints, including ProStride. Conducted by: TOYOKAZU TAKEUCHI, PhD., CPO KEIZO YAMAMOTO, PhD.

GAIT ANALYSIS COMPARISON: VERTICAL COMPONENT OF THE PROSTHETIC LIMB SIDE

In all knee joints, a complete bimodal nature is not observed. However, ProStride smoothly reaches toe-off. ProStride provides consistent and stable support. As the patient moves through the stance phase, the knee effectively absorbs impact and maintains balance, ensuring a smooth progression. In summary, the ProStride knee not only supports a stable stance but also ensures that the patient moves through this phase effortlessly, culminating in a smooth and confident toe-off, which is critical for maintaining a natural gait rhythm.

GAIT ANALYSIS COMPARISON: ANTERIOR-POSTERIOR COMPONENT OF THE PROSTHETIC LIMB SIDE

Despite there being almost no difference observed in acceleration during step crossing, ProStride shows adequate deceleration, which is necessary to control forward momentum and prepare the limb and body for the subsequent phase of gait, helping to prevent jarring impacts that could lead to instability or discomfort.

 

SPEED OF ANTERIOR-POSTERIOR MOVEMENT OF CENTER OF PRESSURE (COP)

The Speed of Center of Pressure, or COP, refers to how quickly the pressure point moves across the sole of the foot during the gait cycle. As we walk, the COP travels smoothly from the heel towards the toes. The rate at which this transition occurs provides crucial insights into the smoothness and efficiency of our walking dynamics. In the case of ProStride, the early stance phase shows little difference in COP speed compared to other prosthetic joints, indicating a stable initial contact. However, where ProStride truly excels is during the mid-stance phase, where the COP speed accelerates smoothly. This smooth acceleration continues toward the end of the stance phase, closely mimicking the natural gait observed on the healthy side. This seamless transition of weight from heel to toe in ProStride ensures that each step feels natural and effortless, contributing significantly to a more balanced and comfortable walking experience.

 

KNEE JOINT ANGLE CHANGE

The maximum flexion angle during the swing phase with ProStride closely matches that of natural walking, approximately 60 degrees. The timing to reach this maximum flexion is consistent with other high-quality prosthetic knee joints. ProStride demonstrates strong control over swing phase flexion limitation and its timing.

FOOT CLEARANCE

Higher knee angle velocity during the early swing phase suggests a rapid knee rise, which is necessary for a smooth and efficient gait. The foot is more distant from the ground. This means the Prostride has a better toe clearance, reducing the risk of stumbling for a more secure step.

STUDY OUTCOMES

1) One of the key strengths of the ProStride knee is its versatility. This prosthetic knee system is engineered to deliver a high-quality gait experience for a wide range of patients, regardless of their activity level.

2) ProStride provides the same reliable performance and is accessible to K3 patients who require a balance of stability and mobility for everyday activities.

3) The knee’s adaptability means it can be tailored to meet the unique demands of each user, ensuring that they enjoy a natural and comfortable gait. Whether its walking on uneven terrain or navigating stairs, ProStride’s responsive design provides the support and flexibility patients need to feel confident in their movements.

ALPS ProStride® Prosthetic Knee: Easy to install and intuitive to use. Installation is straightforward, requiring just a few steps.

CONFIGURE THE SETTINGS: The intuitive user interface allows clinicians to program the knee withjust a few simple inputs. ProStride’s smart sensors automatically calibrate to the patient’s gait pattern, making adjustments quick and accurate.

FINE TUNING: Final adjustments can be made swiftly through a user-friendly app, allowing for real-time feedback and ensuring optimal performance.

IMPORTANT: This process not only saves valuable time, but also ensures that clinicians can focus more on patient care rather than on technical setup. The ProStride knee is designed to be as user-friendly as possible, allowing practitioners of all experience levels to install and program it efficiently.

DOWNLOAD THE COMPLETE STUDY AS PDF

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INTRODUCING BIOSTEP® EVO GAIT ANALYSIS

This study compares the dynamic features of ALPS BioStep® Evo with other dynamic response feet, offering insights into the unparalleled performance and innovative technology of the Evo Foot.
The study delves into various facets of gait analysis, unveiling the exceptional performance of BioStep® Evo.

From its vertical floor reaction force to its ankle power dynamics, BioStep® Evo stands out with a

gait experience remarkably close to natural.

Measurement System

Professor Yamamoto employed a sophisticated measurement system, featuring 12 infrared cameras, 4 force plates, and a central computer for precise data collection. This carefully controlled setup allowed for a detailed observation and analysis of gait, ensuring a true-tolife walking scenario.

The results, visualized through a state-of-the-art visual 3D program, provide a holistic understanding of BioStep® Evo’s performance. The skeleton on the left side of the screen represents the prosthetic user, the blue lower limb represents the prosthetic leg, and the red lower limb represents the intact leg. Using this system, the study measures various key elements , such as ground reaction force during the different steps of the stance phase, and represents them on the Y axis of the graphs.

INSIGHTS FROM GAIT ANALYSIS

The study measured various aspects, showing how BioStep® Evo’s NRG™ Technology replicates natural movement:

• Vertical Component of Ground Reaction Force
• Anterior-Posterior Direction of Ground Reaction Force
• Ankle Angle
• Ankle Power
• Knee Joint Angle

 

Vertical Component of Ground Reaction Force

Gait remarkably close to natural

From this graph, it becomes evident how the gait of the BioStep® Evo closely resembles that of the intact limb, confirming that NRG™ Technology of BioStep® has been designed to replicate the natural movement of the calf and shin muscles.
BioStep® Evo exhibited a higher and more prolonged first peak, indicating a smoother response and roll-over, while competitors showed weaker shock absorption capabilities, potentially causing discomfort and walking issues.
BioStep® Evo’s line shape closely resembles the intact limb indicating a more biomimic design compared to the other feet and an enhanced dynamic response.

 

Anterior-posterior direction component of the ground reaction force

Fluid Step with a continuous dynamic response

BioStep® Evo proved to provide consistent and smooth force curve throughout the mid-stance phase, distinguishing
it from its competitors. With BioStep® Evo, the transition from braking (negative value on the y-axis) to propulsion (positive
value) is smooth, mirroring natural walking patterns. Conversely, in the other two dynamic feet tested, a tendency highlighted by circle 1, referred to as a “dead spot,” lead to recurrent braking. Towards the end of the stance phase, BioStep® Evo demonstrated higher acceleration, closely resembling a intact limb.

 

Ankle Angle

Remarkable range of motion in both plantar flexion and dorsiflexion

The BioStep® Evo line representing plantar flexion and dorsiflexion shows a trend which more closely resembles that of the intact limb while the other two feet have a smaller plantar flexion angle as you can see by the pattern of the lines highlighted in circle 1. BioStep® Evo displayed a remarkable range of motion in both plantar flexion and dorsiflexion, emphasizing its excellence in ankle joint design.

 

Ankle Power

Biomimic gait with superior shock absorption

Evo Foot displayed more natural patterns during the load-response phase and smooth transitions into mid-stance and terminal stance. You can see how the line trend of BioStep® Evo shows in detail:

• greater shock-absorption (Circle 1)
• facilitation of forward leaning (Circle 2), similar to the natural stance where the stretched anterior tibialis muscle pulls on the lower leg
• a smooth waveform after the mid- stance, with a pattern almost identical to that of the intact limb (Circle 3)

 

Knee joint angle

Same trend of the angle of flexion of the healthy limb

We delved into additional insights of the study regarding the knee joint angle, which further validate the effectiveness of BioStep® Evo in providing a natural and comfortable walking experience.
In this specific case the measurement was carried out during the whole gait cycle. The most interesting outcome was that during the stance phaseBioStep® EVO proved to be the only foot providing the same flexion angle trend as the intact limb.

 

CONCLUSION

The gait analysis study of BioStep® Evo positions it as a frontrunner in dynamic prosthetic feet, providing evidence of its capabilities in terms of roll-over smoothness, superior shock absorption, and allowing a natural, reactive gait.
It affirms its effectiveness in providing a natural and comfortable walking experience.

DOWNLOAD THE COMPLETE STUDY AS PDF

We are delighted to announce the arrival of our brand-new  2024 catalogue, specially designed to meet the unique needs of CPOs and prosthetic industry professionals.

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What Awaits You in Our New Catalogue:

🌟 Newest Product Range
Explore our latest prosthetic solutions, engineered to enhance your patients’ mobility, comfort, and quality of life. We are proud to introduce innovations that will make a difference.

💡 Comprehensive Descriptions
Get in-depth information about each product, including specifications, features, and unique benefits, allowing you to choose which product aligns best with your patients’ lifestyles. Use the QR codes to access our product selectors easily.

🌐 User-Friendly Navigation
Finding the prosthetic solution that suits your needs has never been easier. Our catalogue is thoughtfully organized, making your search fast and efficient.

We have updated the look of three of our liners, while maintaining that same high standard that has always been the hallmark of ALPS’ products.

 

EASYLINER^TM

ALPS EasyLiner^TM is a prosthetic gel liner containing an antioxidant which is an effective scavenger of free radicals, and hydroxyl groups, with beneficial effects on the skin of the residual limb. It provides a combination of softness, strength, and cushioning thanks to ALPS EasyGel.

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EXTREME LINER

ALPS Extreme Liner is a prosthetic liner made of Grip Gel or HD Gel that ensures excellent adhesion to the residual limb, improving control of the prosthesis, without limiting comfort. It is recommended for patients, both transfemoral and transtibial, with medium activity levels whose skin is in good condition and who are aiming to maintain a good level of control of the prosthetic leg.

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GENERAL PURPOSE LINER

ALPS GP prosthetic liner is made of Grip Gel that ensures optimum adhesion and comfortably conforms to the shape of the residual limb. It is recommended for patients with low activity levels and good skin conditions; it is also indicated for irregularly shaped residual limbs and those with bony protuberances.

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It’s easy to select the best liner to suit your individual needs using our specially developed app

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ALPS has recently introduced an innovative and skin friendly silicone prosthetic liner for lower limb amputation. This liner provides a solution to some of the clinical problems and disadvantages of silicone in skin-contact applications due to the inherently high coefficient of static friction typical of silicone polymers.

History or prosthetic liners

Silicone liners have been used since the 1980s in the prosthetic industry because 2 component RTV silicones were commonly used in prosthetic facilities for a number of applications thanks to the ease of mixing and to the room temperature cure as well as to the great detail resolution that silicone provided when molded.

Therefore when the first triple S sockets (silicone suction sockets) were developed by Carlton Fillauer in the 1980’s he simply used, with great success,  the 2-component silicones that he already had readily available on his lab bench.

Ossur, then, developed the first non-custom silicone liner using a matrix reinforcement at the distal end, making a more convenient, off-the-shelf version of the 3S liner, so to speak.

In many respects silicone seemed, at the time to be the ideal choice for prosthetic liners as it has the following desirable properties:

• Easy to clean
• Repels dirt
• Does not stain
• Does not retain bad odors
• Has a high coefficient of heat transfer (cools the limb better)
• Can be molded in very thin sections, resulting in very light liners

However, the high coefficient of static friction of silicone caused skin blisters in patients with sensitive skin.

Therefore approximately 25% of patients could not tolerate long term use of silicone liners.

The high coefficient of friction per-se would not be a huge problem if the modulus of elasticity of silicone were low enough to allow the skin to move when subjected to shear forces.

The modulus of silicone though is not low enough for many patients resulting in blistering of the skin.

Such blisters are prone to be a source of more serious sores especially in patients with poor vascularity.

Over the years different additives have been developed that are introduced in the silicone rubber formulation which exude from the liners and provide lubricity on the skin.

And thermoplastic gel liners have been developed having a much lower modulus of elasticity than silicones and some like the EasyGel liners that have a modified surface to eliminate sticking altogether.

 ALPS skin friendly silicone liners

Prosthetic liners manufacturers tried to solve the above-mentioned issues by including additives to the silicone to reduce the coefficient of static friction; however, the exudate substance can collect dirt, exacerbating the risk of skin issues, and the prosthetic liner may become slippery.

Alps expertise in processing silicone allowed our engineers to come up with a new manufacturing method which improved the friction characteristics of the silicone prosthetic liner.

The surface of the prosthetic liner has been modified, to create micro craters that reduce the static friction without any additives, resulting in a completely skin friendly silicone.

Silicone with the modified surface layer shows a reduction of 80% of the coefficient of static friction, as shown in the graph below.

Alps Silicone Pro liner is manufactured using pure silicone. This makes our Silicone Pro suitable for a wide range of amputees, including elderly and vascular patients with a lower limb amputation.

The Silicone Pro stands alongside our liner manufactured in EasyGel, Grip Gel and the newest High Density Gel (Silicone Equivalent).