A must-see for thigh amputees! The prosthetic knee joint is so selected, the gait is natural and safe
For thigh amputation users, the prosthetic knee joint is the "core component" that determines walking ability, naturalness of gait and safety of use. It not only supports the weight of the body, but also simulates the flexion, extension, cushioning and stabilizing functions of the normal knee joint. Choosing the right knee joint can allow you to easily cope with daily walking, going up and down stairs, etc. Choosing the wrong knee joint may lead to a stiff gait, easy fatigue, and even increase the risk of falling. Today we will analyze the common types of thigh prostheses and knee joints to help you find the one that best suits you.
First, let’s clarify: the core role of the thigh prosthetic knee joint, why it cannot be “just used”
The thigh prosthetic knee joint connects the socket (wrapping the residual limb) and the prosthetic foot, and assumes more complex functions than the calf prosthesis, mainly reflected in 3 Aspects:
Support and stability: When standing, the knee joints need to be firmly "locked" to avoid leg weakness and bending, and to support the whole body weight; when walking, they must be "unlocked" at the right time to complete flexion and extension in conjunction with the gait.
Gait simulation: By adjusting the flexion and extension speed and buffering strength, it simulates the movement trajectory of normal people's knee joints, such as the natural bending of the knee when walking and slow buffering when landing, reducing the "mechanical feeling".
Adapt to scenes: Respond to the needs of different scenarios, such as the need to flex and stretch flexibly when going up and down stairs, and the support angle needs to be adjusted when going up and down slopes to avoid imbalance in complex environments.
If the knee joint is improperly adapted, such as insufficient support, it is easy to shake when standing; insufficient flexibility, difficulty in going up and down stairs, long-term use may also cause strain on the waist and the healthy side of the knee - this is why "accurate selection" is more important than "choosing randomly".
Two and 5 types of common thigh prosthetic knee joints: characteristics, suitable people and scenarios
1. Manual Lock Knee: basic and stable model, suitable for "low activity + weak balance" User
Core Features
Manual locking of the knee joint requires manual operation (such as pressing a button, pulling a pull cord) to achieve "locking" and "unlocking". The locking ensures stability when standing, and the unlocking allows for flexion and extension when walking. It has a simple structure, an affordable price, and a low failure rate.
Adapted to the crowd and scene
Applicable crowd:
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Users who have very little daily activity and mainly walk at home and short distances slowly (such as the elderly and users recovering from surgery);
Weak balance ability and insufficient lower limb strength, need Users with "absolutely stable" support;
Users with limited budget who only need to meet basic standing and walking needs.
Applicable scenarios : Slow walking on flat ground, standing indoors, moving short distances after sitting for a long time, not suitable for going up and down stairs, up and down slopes or complex roads.
Advantages and Disadvantages
Advantages: Extremely stable, affordable Low price, easy maintenance, no complex electronic components, no need to worry about failure;
Disadvantages: manual operation required, poor gait continuity (need to raise your hand frequently to unlock when walking) / locked), low flexibility, easy to fatigue after long-term use.
2. Automatic Lock Knee: Convenient and stable, suitable for "light daily activities" User
Core Features
Automatic locking of the knee joint requires no manual operation and can be automatically locked/unlocked through "weight sensing": when standing, press down on the body weight to lock; when walking, gently lift the residual limb back to unlock the flexion and extension, which is more convenient than manual locking.
Suitable for people and scenarios
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Daily activities are light and require frequent Users who frequently walk on the ground indoors and outdoors (such as shopping for groceries, walking, picking up children);
The balance ability is average, but they hope to reduce the Users who have difficulty with manual operation (such as middle-aged users);
Users whose residual limbs are weak and unable to flexibly control complex knee joints.
Applicable scenarios : Walking on flat ground, moving short distances on flat roads, you can try to slowly go up and down small slopes (need to adapt), not suitable for fast walking, going up and down stairs.
Advantages and Disadvantages
Advantages: No manual operation required, more consistent and stable gait Good quality, moderate price, more convenient than manual locks;
Disadvantages: limited flexibility, fixed flexion and extension speed, unable to adapt to fast walking or complex roads, and still difficult to go up and down stairs.
3. Pneumatic knee joint (Pneumatic Knee): flexible cushioning model, suitable for "moderate activity" users
Core features
Pneumatic knee joint passes The "pneumatic cylinder" adjusts the flexion and extension speed and buffering strength, and can automatically adapt according to the walking speed (faster flexion and extension if you walk faster, slower flexion and extension if you walk slower). It also has a good buffering effect, which can reduce the impact on the residual limb when landing.
Adapted to the crowd and scene
Applicable crowd:
Users who have moderate daily activity and need to walk frequently (such as commuting, visiting shopping malls, walking outdoors);
Have requirements for a natural gait and want to reduce Users with a "mechanical sense";
Users with good residual limb strength and the ability to independently control walking speed (such as young users and middle-aged users in good physical condition).
Applicable scenarios: : walking quickly on flat ground, going up and down gentle slopes, lightly going up and down stairs (requires practice), and can cope with mildly uneven roads (such as stone roads).
Advantages and Disadvantages
Advantages: flexion and extension speed can be adapted, good buffering effect, relatively stable gait Naturally, it is more flexible than automatic locks;
Disadvantages: Pneumatic cylinders are easily affected by temperature (low temperatures may cause slow response), air leakage may occur under long-term high-intensity use, and the price is slightly higher than automatic locks.
4. Hydraulic Knee: an all-round adaptable model, suitable for "medium to high activity levels" User
Core Features
The hydraulic knee joint accurately controls the flexion and extension speed and buffer strength through the "hydraulic cylinder". The adjustment accuracy is higher than that of the pneumatic knee joint. It can adapt to different walking speeds (such as slow walking, fast walking), and can provide more stable support when going up and down slopes and stairs. Some high-end models also have "Multi-mode adjustment" (such as sports mode, daily mode).
Adaptable to people and scenes
Applicable Crowd:
Users who have a large amount of daily activities and need to deal with various scenarios (such as commuting to work, shopping, outdoor play);
Hope that the gait is close to that of normal people and they can move up and down independently Users who use stairs and go up and down slopes;
Users who have strong ability to control their residual limbs and pursue high comfort and naturalness (such as young office workers and active middle-aged users).
Applicable scenarios : brisk walking on flat ground, up and down stairs, up and down slopes, rough roads (such as grass, gravel roads), some styles can support light exercise (such as jogging, cycling).
Advantages and Disadvantages
Advantages: high adjustment accuracy, natural gait, wide adaptability to scenes, stability and flexibility The cushioning effect is better than that of pneumatic knee joints;
Disadvantages: higher price, slightly heavier than pneumatic knee joints, requiring regular maintenance (such as replacing hydraulic oil), and slight jamming may occur in low temperature environments.
5. Intelligent Knee (Microprocessor Knee): Technology-empowered model, suitable for “high activity + pursuit of ultimate experience” User
Core Features
The smart knee joint has built-in sensors and microprocessors, which can monitor walking speed, road slope, and body center of gravity changes in real time, and automatically adjust the flexion and extension angle, support strength and buffering mode (such as automatically increasing the flexion and extension angle when going up and down stairs, and strengthening buffering when going downhill). Some styles also have "Fall Protection" (automatically locks when imbalance is detected).
Suitable for people and scenarios
Suitable for people：
The amount of daily activities is high and you need to deal with complex situations frequently. Users in complex scenarios (such as business trips, travel, sports);
Pursue the ultimate naturalness of gait and hope to restore walking ability close to normal. Users who are young, have strong learning ability, and are willing to adapt to smart devices (such as young office workers and sports enthusiasts).
Applicable scenarios : walking quickly, going up and down stairs/steep slopes, running (some styles), mountain climbing, dealing with complex uneven roads (such as mountain roads, steps), and can support a variety of sports scenarios.
Advantages and Disadvantages
Advantages: most natural gait, adaptable to scenes It is extremely flexible, intelligent adjustment does not require manual operation, and has a safety protection function, which can restore mobility to the greatest extent;
Disadvantages: high price (usually hydraulic knee joints) 2-3 times), requires charging (lasts about 1-2 days), is complicated to maintain (requires professional institutions), and is slightly heavier than a hydraulic knee joint.
3. 4 "Personalized" Judgment Criteria for Choosing Knee Joints
In addition to understanding the characteristics of different knee joints, you also need to "accurately match" based on your own situation to avoid "blindly choosing expensive" or "Waste of function":
1. Press "Activity" to select: Activity determines functional requirements
Low activity (<1,000 walks per day) walking, mainly at home): choose manual locking of the knee joint, which is stable, worry-free and cost-effective; (mainly on flat ground): Choose Automatic locking of knee joints to reduce the trouble of manual operation; step, multi-scene switching): Choose pneumatic knee joint or basic model
Hydraulic knee joint , balancing flexibility and practicality;
High activity level (walking >8000 times per day) step, complex scenes): Choose high-end hydraulic knee joint or intelligent knee joint to adapt to more scenes and improve the experience.
2. Press "Residual Limb and Physical Condition" to select: Ability determines the upper limit of adaptation
Short residual limb/weak strength/ Poor balance: Prefer manual lock or automatic lock Lock the knee joint, focusing on stability to avoid risks caused by difficult control;
The residual limb length is moderate / Good strength / average balance: choose pneumatic knee joint or basic hydraulic knee joint, taking into account flexibility and stability;
The residual limb condition is good / strong / Good balance: Choose high-end hydraulic knee joints or intelligent knee joints to give full play to your control capabilities and improve the naturalness of your gait.
3. Press "Life Scene" to select: environment determines the function focus
Single living scene (only indoor / Flat ground): manual lock, automatic lock or basic air pressure knee joint is enough;
Requires frequent going up and down stairs / Slope: Must choose Hydraulic knee joint or Smart knee joint, its precise adjustment function can cope with complex scenes;
Frequent outdoor activities /Sports: Choose intelligent knee joint or sports hydraulic knee joint to adapt to rough roads and high-intensity activities.
4. Press “Budget” Choice: Balancing demand and cost
Limited budget (pursuing basic functions): manual lock (the most cost-effective), automatic knee joint lock;
Medium budget (taking into account functions and costs): pneumatic knee joints, basic hydraulic knee joints;
Sufficient budget (pursuing the ultimate experience): high-end hydraulic knee joints, smart knee joints.
4. Avoid pitfalls when purchasing: 3 “common mistakes” to avoid
"Blindly choose the smart model, thinking that the more expensive the better": Although the smart knee joint is good, it requires high control and learning ability of the residual limb. If the balance is poor and the strength of the residual limb is weak, it may not be able to fully function, but the operation will be complicated and affect the use. It is better to choose a more stable automatic lock or air pressure model;
"Skip the try-on and shop online directly": Different brands of knee joints, even if they are of the same type, have differences in adjustment accuracy, weight, and feel. Be sure to try them on under the guidance of a prosthetist to feel the stability when standing and the continuity when walking, to avoid "Blind selection" leads to discomfort;
"Ignoring maintenance needs": Hydraulic and smart knee joints require regular maintenance (such as oil changes, charging, calibration). If you don't have time or are inconvenient to visit the store frequently for maintenance, you can give priority to manual locks and automatic locking knee joints with simple structures to reduce subsequent troubles.
5. Finally: Professional evaluation is the core of "choosing the right one"
No matter which knee joint you choose, it is recommended to go to a regular prosthetic institution first and let a professional prosthetist do a "personalized evaluation":
Inform the prosthetist in detail about your daily activities, life scenes, and exercise needs;
Cooperate with residual limb measurement, balance ability testing, and gait simulation;
On the recommendation of the prosthetist, try on 2-3 different types of knee joints to compare standing stability, walking consistency, and residual limb comfort;
Understand the maintenance methods and warranty period of the selected knee joints to ensure that subsequent use is guaranteed.
There is no “best” thigh prosthetic knee joint, only “the most suitable” – if you choose the right one, it will become your walking “partner” and help you cope with your daily life easily; if you choose the wrong one, it may become a burden. I hope this guide can help you clarify your thoughts, find the one that suits you best, and take every step with confidence.
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