JC

Assistive Technology Upper and Lower Extremity Prosthetic Devices Review

Objectives of Lower Extremity (LE) Prosthesis

Describe LE prosthesis for different amputation levels:

  • Each type of prosthesis is specifically designed to accommodate the unique challenges and needs associated with various amputation levels, providing different functionalities and levels of mobility.

Identify components for above/below knee amputation:

  • Above-knee (AK) prostheses require components that include a knee joint to allow for movement, while below-knee (BK) prostheses utilize components such as a foot-ankle assembly and shank to facilitate ambulation.

Discuss variations and their implications:

  • Various prosthesis designs exist, each with implications for the user's mobility, stability, and comfort depending on their physical condition and activity level. For instance, transtibial amputees may face different challenges than transfemoral amputees.

Assess advantages/disadvantages of each variation:

  • Each prosthetic design comes with pros and cons; for example, a polycentric knee joint provides a more natural gait but may be heavier, which can be a disadvantage for some patients.

Types of Amputations and Prosthetic Devices

Partial Foot and Syme's Prostheses:

Toes/ray amputation:

  • Designed for individuals with partial foot amputations, these devices include shoe inserts/toe fillers that support remaining toes and provide balance, as well as varying designs based on the level of amputation.

Transmetatarsal:

  • Custom-molded insoles and elastomer prostheses are tailored for specific needs, ensuring comfort and stability for the wearer.

Lisfranc & Chopart:

  • Modified shoes and prosthetic boots enhance mobility for individuals missing specific parts of the midfoot, with designs localized to support existing bones and soft tissues.

Syme & Boyd:

  • Variations are designed for end bearing stumps; these prosthetics utilize specific socket configurations to optimize weight distribution and improve comfort when walking.

Transtibial Prosthesis (below-knee):

  • Retains anatomical knee; common for vascular disease amputations, allowing users a better range of motion. This design often allows for faster rehabilitation timelines.

Components:

  • Foot-ankle assembly, shank, socket, and suspension work together to facilitate effective movement and weight support. Each part plays a key role in overall functionality.

Foot-Ankle Assemblies

  • Solid Ankle Cushion Heel: basic; minimal maintenance, ideal for inactive users, offering shock absorption from ground impact.

  • Energy Storing/Dynamic Feet: designed for active individuals, these feet store and release energy upon impact, assisting during push-off to enhance walking dynamics.

  • Single-Axis Feet: provide a hinge for controlled movement but can limit the variability of motion often needed on uneven terrain.

  • Multiple-Axis Feet: adaptive to uneven surfaces; more durable, ideal for users engaging in diverse environments.

  • Specialized Feet: designed for specific activities (e.g., swimming) to improve performance and enhance the user's overall experience with the prosthesis.

Shank Components

  • Exoskeleton Shank: strong, durable but less lifelike in appearance; often used for heavy loading conditions or in rough environments.

  • Endoskeleton Shank: modular, adjustable for optimal fit and comfort, providing a more natural appearance that can be customized for the user.

Socket Components

  • Hard Socket: pros include durability; cons involve difficulty in fitting to softer tissues.

  • Soft Insert: cushioning for mature limbs, allowing for improved comfort by minimizing pressure points.

  • Flexible Inner Socket: adapts with weight, beneficial for fluctuating limb volume.

  • Patellar Tendon Bearing (PTB): designed to distribute pressure evenly for more stability, particularly during standing and walking activities.

Suspension Systems

  • Various designs (corset, cuff, SC, SC/SP) maintain stability and fit, crucial for comfort and effective use.

  • Suction systems: create airtight seals for secure fit, offering increased stability for active users.

Knee Unit Types

  • Single Axis: basic operation, provides limited stability and lacks advanced mobility features.

  • Polycentric: designed to replicate more natural walking patterns, facilitating a smoother gait simulation.

  • Manual Lock: enables stability through locking mechanism, although it may compromise some mobility during walking.

  • Pneumatic & Microprocessor: represent the latest technology in prosthetics; offers advanced control and lightweight properties but may come with a higher expense.

Considerations

  • Fit and comfort are critical to the success and usability of the prosthesis; users often experience a risk of skin irritation, necessitating regular adjustments for volume changes and comfort.

  • Variations based on patient capabilities and lifestyle demands are essential considerations to maximize function, whether that includes active lifestyles or more sedentary preferences in