Everything You Need To Know To Find The Best prosthetics knee joint

After the above knee amputation, you may feel hopeless because you cannot do what you have already done. With advanced technology, you can go forward to the next level. Many people adapt prosthetics, finding new ways to stay active and live happy lives. Prosthetic knee joints enable movement with confidence and free-flowing natural motion.

With competitive price and timely delivery, PFC sincerely hope to be your supplier and partner.

This blog will explain the types of prosthetic knees, their workings, and essential factors when selecting one. Whether for you or those looking to assist a loved one transitioning in life after the amputation, remember that the right choice of limb enables ease in everyday movements.

What are Prosthetic Knee Joints?

Knee joint is one of the most significant joints in the human body. It links the femur to your tibia, allowing you to stand straight, walk, and even balance yourself. The decision to remove this crucial joint due to above-knee amputation, whether from trauma, diabetes, or other medical conditions, can significantly impact a person’s quality of life. Above-knee amputation impacts mobility and functionality, but prosthetic knees are a game-changer.

Artificial knee joints come equipped with additional capabilities that allow them to deliver the ability to move and incorporate seamlessly back into everyday activities with the confidence to live your own life. See how these technologies transform problems into possibilities for well-being and meaningful life.

What are the 6 Types of Prosthetic Knee Joints

1. Manual locking knee joint: The locking system is stiff and can only be unlocked when a release mechanism is used. It can be more useful in the early stages of rehabilitation to help the user gain more confidence.  
2. Single-axis knee joint: The most common knee joint works in the single-axis when the knee bends and straightens.  
3. Polycentric knee joint: It comforts you with multiple axes of rotation or pivot points that allow for more natural movements.
4. Pneumatic knee joint: It relies on air to assist in flexing and extending muscles at the knee joint. It has an inner piston, while an outer cylinder accommodates air inside. During the piston stroke, it pumps the air, controls the pressure on the knee, and allows the amputee to walk at different speeds.
5. Hydraulic knee joint: This prosthetic knee joints is articulated, and the hydraulic system regulates knee movements. It is an artificial limb that imitates the knee’s functionality. The joint has a piston within a cylinder filled with fluid to stabilize the knee so that it does not swing, and a rubber bumper compresses the stance phase and creates resistance.
6. Microprocessor-controlled knee: This type of artificial knee employs a computer to analyze the users’ requirements and consequently coordinate the knee motion to emulate a regular walk. Usually, it recognizes a misstep and increases the knee’s stiffness, allowing you to traverse terrains. You can control these kinds of microprocessor artificial knees in different ways, such as by controlling the swing phase only, the stance phase only, or both the swing and stance phases.

Top Features and functionalities of the knee joint

• Adjustable flexion and extension: The model is designed for your flexibility requirements.
• Stability mechanisms (stance phase stability): It guarantees stability and helps movement throughout the stance phase.
• Swing phase control: Improves stability and fluidity of the walk during the swing phase.
• Customizable settings for different activities: Innovative and versatile, these settings are suitable for walking, sports, and any other time frame.

Material and Design Considerations Before Choosing One

1. Lightweight materials: Extra options like titanium and carbon fiber ensure the comfort and ease of daily use of the above-knee artificial limb.
2. Durability and weather resistance: They are designed to withstand demanding and challenging climates and deliver optimum performance in any environment.
3. Aesthetic designs: Cosmetically appealing prosthesis that fit specific shapes and sizes perfectly balance form and function for your above-knee artificial leg.

Fitting and Alignment of Prosthetic Knees

• Proper alignment ensures a natural gait and maximum comfort, optimizing the movement of the knee joint when using a prosthetic leg.
• Prosthetists’ expertise is vital for precise fitting and customization, ensuring seamless integration of the knee joint for smooth motion.
• Initial fitting challenges involve fine-tuning the knee joint alignment to overcome discomfort and achieve the perfect fit for a prosthetic leg above knee.

Biomechanics of Artificial Knee Joints

1. Mimicking natural gait: The modern prosthetic knees are designed to approximate the mechanical properties of natural knee joints to facilitate the motion of prosthetic joints.
2. Load distribution and stability: Knee joint movement ensures objects are well distributed in contact and gives support and balance during usage.
3. Impact on hip and ankle joints: Similarly, in the case of an above-knee prosthetic limb, a knee effectively distributes the load from the hip and the ankle, thereby promoting mobility.

Top 3 Benefits of Using Artificial Knee Joints

• Improved mobility and balance: It makes daily movements easier, including walking and climbing stairs.
• Participation in sports and activities: Facilitates running, cycling, or yoga, and other favorite activities and hobbies can be retained.
• Enhancing confidence and quality of life: It boosts confidence by enabling natural, comfortable movement in social settings, allowing you to engage with others effortlessly and focus on the moment.

Conclusion

Amputation alters life, whether the individual desires it or not, and a prosthetic knee joints means getting a do-over. High-tech prosthetic knees combined with professional fitting let you move again, improve your quality of life, and help you feel whole. From walking to all other activities, such prosthetic innovations guarantee that individuals can use every activity without restraint.

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KARE Prosthetics and Orthotics solution provides quality prosthetic and orthotic devices to wear and practice transitioning to the device. Our new technologies ensure you get the mobility aid that suits your way of life. For your prosthetic needs, visit KARE near you for quality health care and services.

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Table of Contents

There are many prosthetic leg options to choose from, and the best fit will be dictated by an individual’s level of injury, physical factors, complications, as well as their lifestyle and vocational or recreational goals.

Every amputation is different, and it is critical that persons who have sustained an amputation work with a certified prosthetist and physiotherapist to determine which kind of prosthesis will be the best option for them.

In this article, we will highlight prosthetic leg options and physiotherapy for through-knee or above knee amputation.

Table of Contents:

• What is a prosthetic leg?
• Common causes and complications of amputations
• Types of knee prostheses
• Mechanical knees
• Single axis knees
• Polycentric knees
• Manual locking knees
• Weight activated stance control knees
• Pneumatic or Hydraulic Knees
• Computerized knees
• Physiotherapy after leg amputation
• Conclusion

What is a Prosthetic Leg?

Prosthetic legs allow an individual who has sustained an amputation to walk with a more normal and energy efficient gait pattern and will often allow them to walk without the need for assistive devices such as crutches or walkers. In addition to enabling a more normal gait pattern, they allow the user to accommodate for sitting/standing, stairs/ramps as well as uneven terrain and different walking speeds.

A prosthetic leg includes several components including the socket, which is molded to the individual’s residual limb, the suspension system, which is how the prosthesis stays attached to the individual, and the prosthetic leg itself, which includes different options for knee and ankle joints.

Individuals can be fitted for a prosthesis once the wound from the amputation is stable and well-healed, which can be within a few weeks after the surgery. This may be delayed if they have complications related to the amputation.

After an above-knee or through-knee amputation, the residual limb shrinks, as the individual loses muscle mass in their thigh. Users will need to be fitted for multiple sockets over time to accommodate for the decreasing size of their residual limb.

Common Causes and Complications of Amputations

Amputation refers to the removal of a limb due to injury, disease, or surgery. It can be utilized as a surgical procedure to manage discomfort or a disease condition in the affected limb. Individuals can also undergo traumatic amputations resulting from motor vehicle accidents or workplace accidents.

There are several complications related to amputation such as infection, phantom limb pain (residual limb pain), slow wound healing, vascular issues and necrosis, neuromas, edema, and skin breakdown. Phantom pain is a common occurrence after an amputation and is perceived in the limb that has been removed from the body. It is typically characterized as a sharp or burning pain that occurs due to a miscommunication of nerve signals from the brain to the spinal cord.

Types of Knee Prostheses

Prosthetic knees allow a person who has sustained an amputation at or above the knee to regain use of the knee and ankle joints and participate more easily in their daily activities.

Prosthetic knees are divided into two categories, mechanical or computerized. Mechanical knees are further divided into single-axis, multi-axis, and polycentric knees. Each prosthesis has its own unique features which are chosen based on the user’s requirements.

Mechanical Knees

Single-Axis Knees Mechanism and Indications

This is the simplest type of prosthetic knee joint that allows for rotation around a single axis during flexion and extension of the knee. Individuals who use this type of knee require good muscle strength, as this type of prosthesis can be difficult to control. These are sometimes recommended when there are limited economic resources, as it is the most cost-effective option.

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Advantages:

• This is a very simplistic design, durable, as well as light weight, which can be helpful for new amputees, who are just learning to walk.
• Most cost effective

Disadvantages: 

• Due to this simplistic design, the user has to generate significant muscle power to keep the knee stable while standing and walking.
• Creates an unnatural gait pattern due to the simplicity of the single-axis design
• Can be difficult to control the locking and unlocking during gait, putting the user at higher risk for falls and injuries.

Polycentric Knees Mechanism and Indications

Unlike a single-axis knee, a polycentric knee allows multiple points of rotation around several axes. Polycentric joints can have either 4 or 7 bars, meaning that you can either have 4 points of rotation or 7 points of rotation. This type of joint provides good stability when there is involuntary flexion during the heel strike phase of walking because the center of rotation is located more proximally and posterior when the knee is fully extended. This knee is typically recommended for active people, or people who are more likely to walk independently, without a gait aid.

Advantages:

• Can be very stable in stance phase
• Allows the user to sit down with a bent knee
• Due to the multiple axes and the center of rotation, the prosthetic length “shortens” at the start of the swing phase of walking to allow for foot clearance
• Lighter than computerized knees
• Less expensive than computerized knees

      Disadvantages: 

• Much heavier than a single-axis joint prosthesis
• Greater energy requirement of muscles during walking to maintain gait efficiency and balance.

Manual Locking Knees Mechanism and Indications

This type of joint locks while the user is weight-bearing on it. They will need to manually disengage the lock to be able to sit down.

      Advantages:

• Very stable
• Allows for an automatic lock in weight-bearing, with the additional option to manually lock the knee. This is especially important for people with less muscle control and balance, or who need more security while walking on uneven terrain.

      Disadvantages:

• The user will need to swing the leg out or hike the hip to allow for adequate foot clearance during gait. This is an unnatural gait pattern, which can lead to further issues in the future in surrounding muscles and joints.
• Need to manually unlock the knee to sit with a bent knee

Weight Activated Stance Control (Safety) Knees Mechanism and Indications

This knee provides a constant friction force while weight is on the limb. This helps to prevent it from buckling when standing on that leg, while still allowing it to swing freely when unweighted.

      Advantages:

• This is a very stable knee that is commonly prescribed when individuals first start using a prosthesis, and in older individuals and the less active community.
• This is also for people who can exert some control over their knee, but who fatigue quickly after a few steps, or people who forget that they cannot put weight onto a bent knee while using their prosthesis.

      Disadvantages:

• With this prosthesis you are unable to get into a sitting position without taking all your weight off the leg.
• The individual has to take all of the weight off their affected side to allow it to swing resulting in a less efficient gait pattern
• Due to the constant friction in the knee, the individual will walk slower, with smaller steps.

Pneumatic or Hydraulic Knees Mechanism and Indications

Pneumatic/hydraulic components (pistons with cylinders containing air or fluid) can be added to either single-axis or polycentric mechanical knees, as well as computerized knees. This is to help increase mobility and control with the leg and allow the user to vary speeds. When walking faster it will limit the air flow and fluid to reduce the flexion of the knee to allow a faster walking pace. The opposite will happen with a slower gait. Typically, hydraulic knees work well for more active individuals.

      Advantages:

• Allows the individual to walk more comfortably and with a more natural gait pattern.
• This type of knee also allows the individual to walk up and down the stairs with a reciprocal gait pattern, due to the resistance provided during flexion while there is weight on the leg.
• This is both less expensive and lighter than computerized knees.

Disadvantages:

• Hydraulic knees are often more expensive and heavier than pneumatic knees, they also need more maintenance.
• Cost is higher than mechanical knees.

Computerized Knees

Mechanism and Indications

These knees have microprocessors to allow feedback from within the knee or foot joint. Information from the sensors adjusts the range and speed of knee flexion and extension, according to the user’s requirements. Knee extension is powered, and resistance is provided through knee flexion, allowing the individual to more easily get in and out of a sitting position, and navigate stairs using a reciprocal gait pattern.  It also allows for a symmetrical weight distribution and a natural gait pattern.

      Advantages:

• These are much more advanced, which allows the gait to be more natural as well as allowing the leg to adjust to different speeds. Some offer stumble control, which will automatically put the leg into a position to prevent you from falling. This type of prosthesis allows the user to adjust to changes in speed, environment changes and specific situations. These also have different programmable modes for when you are doing different activities (i.e. cycling)
• More efficient gait pattern with less energy expenditure during gait
• Allows the user to navigate stairs using a reciprocal gait pattern

     Disadvantages:

• These are very expensive and need to be charged regularly.
• Heavier than the other options and can also be damaged by different environmental conditions.
• Can be more difficult to cover or wear certain types of clothing overtop
• Learning curve when first starting to use this type of device
• Regular maintenance required

Physiotherapy After Leg Amputation

The nature of rehabilitation after a leg amputation at or above the knee will depend on the client’s goals and physical presentation but will often include:

• Gait assessment and prosthesis training
• Gait aid training
• Transfer training
• Static and dynamic balance training
• Strengthening the hip muscles of the residual limb, as well the muscles of the sound leg, and core.
• Desensitization techniques / mirror box therapy
• Manual therapy – to normalize muscle tension and joint mobility
• Edema management
• Education on activity modification and return to recreational activities
• Collaboration with the prosthetist on adjustments to the prosthesis

Conclusions

When an individual has undergone an amputation at or above the knee, learning to use a prosthetic leg is often a crucial step in the rehabilitation process. A well-fitting prosthesis can help individuals regain mobility and return to their daily activities. This allows the freedom and independence to get back to doing the activities that are important to them.

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