How to choose a prosthetic foot? The key is to look at the ankle joint! Different Types of Adaptation Guides

For lower limb prosthetic users, the ankle joint of the prosthetic foot is the core component that determines walking gait, stability and comfort. Different types of ankle joints vary greatly in terms of support, flexibility, and applicable scenarios. Choosing the right ankle joint will not only make walking more natural and effortless, but also reduce the burden on the residual limb; choosing the wrong ankle joint may lead to abnormal gait, fatigue, and even joint damage. Today I will take you through the common types of prosthetic ankle joints to help you find the one that best suits you.

1. First understand: the core role of the prosthetic ankle joint, why it is the "key choice"

The prosthetic ankle joint connects the prosthetic foot and the calf socket, and is mainly responsible for 3 Big functions, these functions directly affect the daily use experience:

1. Buffering and shock absorption: When walking, the ankle joint can absorb the impact of the ground on the residual limb, reduce the pressure on the knees, hip joints and waist, and avoid joint strain caused by long-term use;

2. Gait adjustment: Through the flexion, extension and rotation of the ankle joint, it simulates the motion trajectory of the normal human foot, making the lifting and landing of the foot more natural when walking, and reduces "Stiff feeling";

3. Stable support: In scenes such as standing, going up and downhill, turning, etc., the ankle joint needs to provide sufficient support to prevent the prosthetic foot from shaking or rolling over, ensuring safe use.

The designs of different ankle joints are centered around the "focus" of these three functions - for example, some focus on flexibility and are suitable for users who need frequent activities; some focus on stability and are suitable for daily slow walking or users with weak balance ability.

Type 2 and 4 common prosthetic ankle joints: characteristics, suitable people and scenarios

1. Static Ankle: basic model, suitable for "low activity" User

• Core features: The fixed ankle joint has no moving parts, the ankle joint angle is fixed (usually in the neutral position), the structure is simple, the price is affordable, the durability is strong, and almost no maintenance is required.

• Adapt to the crowd and scene:

• Applicable people:

• Users who have little daily activity and mainly stay at home and walk short distances slowly (such as the elderly and users recovering from surgery);

• Users with weak balance ability who need stable support;

• Users with limited budget who pursue basic functions.

• Applicable scenarios: : Slow walking on flat ground, standing, moving short distances after sitting for a long time, not suitable for going up and down slopes, stairs or sports.

• Advantages and Disadvantages

• Advantages: strong stability, low price, low failure rate, easy maintenance;

• Disadvantages: poor flexibility, stiff gait, inability to adapt to complex road surfaces, and long-term use may increase the burden on the knees.

2. Monotube Ankle: basic flexible model, suitable for "daily light activities" User

• Core features:The single-axis ankle joint has only one axis of rotation, which can achieve "flexion and extension" movements (similar to the up and down movements of normal human feet), but cannot rotate left and right. The flexibility is between a fixed ankle joint and a multi-axis ankle joint. It has a simple structure and a light weight.

• Adapt to the crowd and scene:

• Applicable people:

• Users with moderate daily activity who need to frequently walk on flat ground (such as shopping for groceries, commuting, and visiting supermarkets);

• Users who have certain requirements for natural gait but do not need complex movements;

• Users who have good residual limb strength and can independently control the balance of the prosthetic limb.

• Applicable scenarios: Walking on flat ground, short-distance movement on flat roads, you can try mild uphill and downhill (pay attention to balance), not suitable for running, jumping or rough roads.

• Advantages and Disadvantages

• Advantages: more flexible than fixed ankle joints, more natural gait, light weight, affordable, easy to operate;

• Disadvantages: unable to rotate left and right, weak stability on uneven roads or when turning, long-term uphill and downhill may increase residual limb pressure.

3. Multi-Axial Ankle: all-round model, suitable for "medium to high activity" User

• Core features:The multi-axis ankle joint has 2-3 rotation axes, which can simultaneously achieve "flexion and extension" and "inversion and inversion" (left and right rotation). It can more accurately simulate the movement trajectory of the normal human foot, with stronger cushioning and adaptability. Some styles also have "Elastic buffer devices" (such as springs, hydraulic rods) further improve the shock absorption effect.

• Adapted to people and scenes:

• Applicable people:

• Users who have a lot of daily activities and need to walk frequently, go up and down stairs, and go up and down slopes (such as office workers and users with a lot of housework);

• Life Users with complex road surfaces (such as steps in the community and uneven roads);

• Users who have high requirements for a natural and comfortable gait and want to reduce joint burden.

• Applicable scenarios: Walking on flat ground, going up and down stairs/slopes, rough roads (such as stone roads, grass), light exercise (such as walking, brisk walking), some high-performance models can support jogging.

• Advantages and Disadvantages

• Advantages: strong flexibility, the most natural gait, wide adaptability to road surfaces, good cushioning and shock absorption, and can reduce pressure on knees and waist;

• Disadvantages: more expensive than single-axis / The fixed ankle joint is high and the structure is complicated. It takes some time to adapt to the operation, and some styles are slightly heavier.

4. Sports Ankle: Professional style, suitable for "Sports enthusiasts"

• Core features:Sports ankle joints are specially designed for high-intensity activities. They usually use a "hydraulic/pneumatic cushioning system" or a "high elastic spring structure", which can withstand greater impact forces, and have strong flexibility and stability. They can support strenuous actions such as running, jumping, and ball games. Some styles also have a "quick adjustment device" that can adjust the hardness of the ankle joint according to the type of exercise.

• Adapt to the crowd and scene:

• < p>Applicable people:

• Users with sports needs (such as running, basketball, cycling, mountain climbing, etc.);

• Young, Users who have good physical function and want to restore high-intensity activities;

• Users whose occupations require frequent exercise (such as outdoor workers, sports coaches).

• Applicable scenarios: Various sports (running, jumping, climbing, ball sports), high-intensity daily activities, and can also be used for walking on complex roads.

• Advantages and Disadvantages

• Advantages: strong impact absorption ability, flexibility and stability, able to support high-intensity exercise, strong durability (designed for sports scenes);

• Disadvantages: high price, heavier than ordinary ankle joints, may be slightly cumbersome for daily use "Redundant" (for example, only used for walking on flat ground, low cost performance), it requires professional guidance to give full play to its performance.

3. 3 "Personalized" Judgment Criteria for Choosing Ankle Joints

In addition to understanding the characteristics of different ankle joints, you also need to "accurately match" your own situation to avoid "blindly choosing expensive" or "Just use":

1. Press "Activity" to select: The amount of activity determines the "flexibility needs" of the ankle joint

• Low activity (walking <1,000 times a day) (mainly at home): Priority is given to fixed ankle joint, which is stable, worry-free and cost-effective; 1000-5000 for daily commuting and shopping): choose single-axis ankle jointor basic modelMulti-axial ankle joint, balancing flexibility and practicality;

• High activity level (walking >5000 times per day) steps, need to go up and down stairs, complex roads): select multi-axis ankle joint to adapt to more scenes and reduce physical burden;

• Sports needs (running, mountain climbing, etc.): Directly choose Sports ankle joint to avoid ordinary ankle joints from being unable to withstand the impact of sports, resulting in injuries.

2. Press "Residual Limb Condition" to select: The residual limb condition determines the "support and cushioning requirements" of the ankle joint

• The residual limb is shorter/weaker in strength: give priority to "Strong Stability + Good Cushioning" styles, such as fixed ankle (low activity) or Cushioned multi-axis ankle joint(medium and high activity level), reducing weight-bearing pressure on the residual limb;

• The skin of the residual limb is sensitive / Easy to fatigue: choose multi-axis ankle joint or sports ankle joint JointThis type of ankle joint has good cushioning and can reduce the stimulation of the residual limb by ground impact force;

• The residual limb shape is stable (such as after amputation) More than 1 year, no obvious shrinkage): You can choose freely according to the amount of activity. If the shape is still changing (such as the postoperative recovery period), it is recommended to choose the basic model first, and then upgrade after the shape is stable.

3. Press "Living Environment" to select: Road conditions determine the "adaptive needs" of the ankle joint.

• The living environment depends on "Mainly flat ground" (such as urban communities, office buildings): single-axis or basic multi-axis ankle joints can meet the needs;

• The living environment has "More steps and slopes" (such as old communities and suburbs): Must select Multi-axis ankle joint, its internal and external turning function can meet the balance needs of going up and down slopes and steps;

• Often used in "Rough Road" Activities (such as outdoor, rural areas): Choose multi-axis ankle joints or sports ankle joints to avoid fixation. / The problem that the single-axis ankle joint is prone to rollover on uneven roads.

4. Avoid pitfalls when purchasing: 3 “common mistakes” to avoid

1. "The more flexible, the better": Although a multi-axis/sportable ankle joint with strong flexibility is good, it requires higher balance ability and residual limb control ability. If you have weak balance ability (such as the elderly), forcing you to choose a highly flexible model may increase the risk of falling. It is better to choose a more stable fixed model;

2. “Only look at the price, not the fit”: Sports ankle joints are expensive, but are only suitable for users with sports needs; if If you just walk slowly on flat ground every day, choosing a sports model will not only waste money, but may also affect the user experience due to heavy weight and complicated operation;

3. < span>"Skip the try-on and buy directly": Different brands and models of ankle joints, even if they are of the same type, may have different feel and adjustment methods. Be sure to try it on under the guidance of a prosthetist to feel the stability and flexibility when walking, and whether there is a sense of pressure on the residual limb, to avoid discomfort caused by "blind online shopping".

5. Finally: Professional evaluation is the key to "choosing the right one"

No matter which ankle joint you choose, it is recommended to first find a prosthetist from a regular prosthetic institution. "Personalized assessment":

• Inform the prosthetist about your daily activity level, life scenes, and exercise needs (if any);

• Cooperate with residual limb measurement, balance ability test, and gait analysis;

• Try on the prosthetist's recommendation 2-3 different types of ankle joints, and compare the walking experience (such as whether it saves effort, whether the gait is natural, whether the residual limb is comfortable).

There is no "absolute quality" in prosthetic ankle joints, only "fit" - if you choose the right one, it will become a "right-hand assistant" for your walking; if you choose the wrong one, it may become a burden on the body. I hope this guide can help you clarify your thoughts, find the one that suits you best, and easily handle every step of your daily life.

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