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Upper Extremity Prostheses

The document discusses upper extremity prostheses. It describes different types of prostheses including passive prostheses for cosmesis, body-powered prostheses that use harness cables, and externally powered electric prostheses. It provides details on terminal devices (hands, hooks), wrist and elbow units, socket designs, and the rehabilitation process. The goals of prosthetic design are comfort, function matched to the user's needs and activities, durability, and cosmesis. Design considerations include the amputation level and residual limb.

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UPPER EXTREMITY PROSTHESES DR. OM PRASAD BISWAL (P&O) CLINICAL PROSTHETIST & ORTHOTIST B.P.O. (N.I.L.D, KOLKATA)
Introduction • Upper limb prosthesis designed to replace, as much as possible, the function or appearance of a missing limb or body part. • Prosthesis can replace some grasping and manipulating functions of hand. • No sensory feedback. • Role of dominant function replaced to contra-lateral hand and prosthesis assists bimanual function.
Factors • Amputation level • Expected function of the prosthesis • Cognitive function of the patient • Vocation of the patient • Avocational interests of the patient • Cosmetic importance of the prosthesis • Financial resources of the patient
Characteristics of an upper extremity prosthesis: • Comfortable to wear • Easy to don and doff • Light weight and durable • Cosmetically pleasing • Must function well mechanically • Have reasonable maintenance • Motivation of the individual
Prosthetic Rehabilitation No prosthesis Passive prostheses or restorations Body powered or conventional External powered or electric Hybrid prosthesis Activity specific
Passive Prostheses or Restorations • For cosmetical purpose only. • Non-functional. • These devices are functional in terms of supporting objects or stabilizing items during bimanual tasks and activities • Requires less harnessing. • Custom made silicone cosmetic covers – expensive and difficult to maintain.
Body-powered Prostheses • Conventional (body-powered) systems include any prosthesis that uses a control cable system to translate volitional muscle force and shoulder or arm movement to operate a terminal device or prosthetic elbow. • These body-powered devices are durable, often weigh less than their electrical counterparts. • Their mechanics depend on proprioceptive feedback through the harness system. • Disadvantages of a body-powered prosthesis revolve around the restrictive nature of its design. • Long-term use of a body-powered prosthesis can accelerate shoulder issues and anterior muscle imbalances and lead to nerve entrapment within the contralateral axilla.
Body Powered Prostheses Components 1. Socket Interface 2. Harness 3. Control cable 4. Wrist Unit 5. Terminal Device (Hand or Hook) 6. And possibly- i. A triceps cuff (Trans-radial) ii. Elbow hinges (Trans-radial) iii. Elbow joint (Trans-humeral) iv. Shoulder Joint (Shoulder Disarticulation or higher)
Terminal devices • Most distal component of an upper-limb prosthesis. • Active Prehensile Devices: – Hooks – Functional hands – Activity specific devices • Passive Terminal Devices: – Cosmetic hands
Passive Hand • Users who opt for a passive prosthesis are primarily concerned with aesthetics or body symmetry rather than function. • But passive prostheses can assist with some actions like pushing, pulling, stabilizing, supporting, light grasping and typing. • Another category of passive terminal devices resembles children's mittens, and hence they are called "mitts." The passive mitt is usually a soft, flexible humanoid shape similar to the cupped human hand.
Terminal devices • Voluntary Opening:  Lower Maximum grip  In closed position, by springs  Patient pulls the cable to open  Prehensile force – spring, relaxed full grip  Simple mechanism • Voluntary Closing:  Higher maximum grip  In open position  Patient pulls the cable to close  Prehensile force – patient, sustained tension for grip  Cumbersome  Greater proprioceptive input
Voluntary Opening Hooks • Hosmer-Dorrance work hooks • Sierra two-load hook • United States Manufacturing Company (USMC) hook • CAPP terminal device (originally developed at the Child Amputee Prosthetics Project at UCLA) • Otto Bock and Hugh Steeper
Cont.
Voluntary Closing Hook • APRL hook developed by the Army Prosthetics Research Laboratory
Voluntary-Opening Hands Voluntary Closing Hands • Becker Plylite Hand • Becker Lock-Grip and Imperial Hands • Robin-Aids Mechanical Hand • Robin-Aids Soft Mechanical Hand • Sierra Voluntary-Opening Hand • Hosmer-Dorrance Functional Hands • APRL Voluntary Closing Hand • Otto Bock System Hand
Becker Plylite Hand • Laminated wood • Movable thumb only • Light weight
Becker Lock-Grip and Imperial Hands • Round wire fingers • Adaptive grasp • Irregular objects • All fingers are movable • Grip adjustable
Robin-Aids Mechanical Hand • Digits 2, 3, 4, and 5 to move away from a stationary thumb • Thumb can be manually prepositioned for normal or large opening prehension. • Very long trans-radial and wrist disarticulation amputation levels • Adjustable length
Robin-Aids soft mechanical hand • The thumb and first two fingers to open • 5 sizes
Sierra Voluntary-Opening Hand • has a two-position stationary thumb • first two fingers to move away from the thumb • "Bac Loc" feature
Hosmer-Dorrance Functional Hands • Permits the prosthetist to adjust finger prehension by the installation of different tension springs. • The hands are available in four sizes.
CAPP Voluntary Opening Hand • “Alligator” or “helper” mechanism • Less body powered force • Children only
APRL Voluntary Closing Hand • Automatic locking when grasp is accomplished • Small opening (with thumb in the standard position) • Large opening (with thumb in the second position) • Adult position only
Otto Bock system hands • a lightweight and inexpensive • several sizes.
Prosthetic Wrist Units • Provide receptacle for connecting terminal device. • Pronation and supination or flexion based on functional activities of patient. Friction Wrist Unit- oOval Friction Wrist Unit Constant Friction Wrist Unit Quick Change Disconnect Wrist Unit Wrist Flexion Units- oSierra Wrist flexion Unit oAPRL Wrist Flexion Unit Rotational Wrist Unit Ball and Socket Wrist Unit
Friction Wrist Units • Supination and pronation by manually rotating the terminal device • Bilateral amputees usually preposition the terminal devices for use by striking one device against the other, thereby rotating it to the desired position of function. • Friction wrist units designed specifically for wrist disarticulation levels of amputation are made as thin as possible to conserve the length of the prosthetic forearm.
Oval-shaped friction wrist units • Available in adult and medium sizes. • The oval configuration provides better cosmesis in cases of long trans-radial levels of amputation. • Since most prosthetic hands have an oval base, the oval-shaped wrist unit provides for a smoother transition from the prosthetic hand to the prosthetic forearm.
Constant Friction Wrist Unit • Provide constant friction throughout the range of rotation of the terminal device. • Constant-friction wrist units are available in both the round and oval configurations
Quick-change wrist units • Designed to facilitate rapid interchange of different terminal devices, usually a hook and a hand-  Remove the terminal device from the wrist unit  Replace the terminal device with a different terminal device  Manually position the terminal device in supination or pronation  Lock the terminal device in the desired attitude of supination or pronation • Adult size and round configuration only.
Wrist flexion unit • Useful for activities at the midline • Unilateral and bilateral amputee (dominant side) • Replaces the common constant-friction wrist and allows manual prepositioning of the hook in neutral, 30 degrees of volar flexion, or 50 degrees of volar flexion.
Sierra Wrist Flexion Unit • Used in addition to the friction wrist. • This dome-shaped device also has three locking positions at zero, 30, and 50 degrees of volar flexion. • Because the entire unit can rotate where it mounts to the wrist, the terminal device covers a much wider arc than with the first alternative. This can be advantageous for the bilateral amputee struggling to perform midline activities. • Significantly heavier than the Flexion Wrist.
APRL Wrist Flexion Unit • 0 deg and 36 deg flexion position • Children only
Rotational wrist units • Amputees who engage in work or avocational activities that exert high rotational loads on the terminal device. • Cable-controlled, positive-locking mechanisms. • In the unlocked mode, these units permit manual prepositioning of the terminal device in almost any attitude of supination or pronation through a 360- degree range. • Once locked in position, these units provide much greater resistance to rotation than do friction units.
Ball-and-Socket Wrist Unit • Permits universal prepositioning of the terminal device with constant friction. • The magnitude of the friction loading can be easily adjusted by the amputee.
Prosthetics Elbow Units • External with or without spring assisted flexion (elbow disarticulation) • Internal, with or without spring assisted flexion • Internal, with rotating turntable (allows internal/ external rotation)
Socket design for partial hand amputation • Socket designs for partial hand prostheses preserve function of wrist joint and other proximal jt. • Trimlines and socket contours are generally dictated by the geometry of the remaining portions of the hand and fingers. Goals:- 1. Protection of the residual limb. 2. bimanual stability 3. provide acceptable cosmesis and durability
Trans-radial and Wrist Disarticulation Prostheses
Sockets • Socket designs and careful consideration- 1. maximizing range of motion. 2. providing stability throughout daily activities. 3. comfortably distributing the forces exerted on the residual limb during movement and suspension. • Socket design for body powered prosthesis- 1. Harness suspended 2. Self suspended
Cont. Socket designs fall into four categories:- 1. Supracondylar brims 2. External suspension sleeves 3. Suprastyloid suspensions 4. Internal roll-on locking liners
SUPRACONDYLAR DESIGNS 1. Muenster socket 2. Northwestern supracondylar socket 3. Modified supracondylar brim 4. Floating brim suspension
MUENSTER SOCKET • Self suspended • Short Trans-radial amputation • The forearm was set in a position of initial flexion (average 35 deg.). • The anterior trim line extended to the level of the antecubital fold, a channel for the biceps tendon. • The posterior aspect of the socket enclosed the olecranon. • The trim line was just above the level of the epicondyles.
• Advantages- 1. Comfort and security. 2. Lifting and holding forces generally superior. 3. "Axial load"—resisting vertical downward force with the elbow extended. • Disadvantages- 1. Active pronation & supination is eliminated. 2. Difficulty in donning and doffing as stump length increases. 3. Decrease in flexion range required modification in case of bi-lateral socket.
NORTHWESTERN SUPRACONDYLER SOCKET • Accommodate all lengths of trans-radial amputations. • Provide an improved range of motion at the elbow. • Narrow M-L dimension • Anterior trimline is below antecubital area, • The anterior trimline, superior to the humeral condyles, should be at least 3/8 inch smaller than the measured M-L dimension at the humeral condyles. • Posterior trimlines be well rounded to accept The contour of the upper arm, proximal to the Humeral condyles. 1/2inch over the olecranon process
MODIFIED SUPRACONDYLER BRIM • Mainly for myoelectric Trans-radial prosthesis. • For long trans-radial amputations. • Has a olecranon cut-out. • Also called three-quarter type below-elbow socket. • Cut-out length should not exceed 50% of the axial stump length.
Advantages- • Ventilation greatly improved, • The skin of the stump remains dry making for a cooler socket in the summer and a warmer stump in the winter. • Skin problems caused by maceration are eliminated • Comfort and wearing tolerance are greatly improved. • Suspension improved • Anatomical elbow is free to move. • Increased elbow flexion range. • Reduced bulkiness at olecranon areas. • Cosmetically pleasing.
FLOATING BRIM SUSPENSION • For long Transradial amputations and wrist disarticulation. • Provides some natural rotation at the wrist and allows for maximum elbow freedom and movement
SUPRASTYLOID SUSPENSIONS For wrist disarticulation with prominent styloid process. 1. Silicone bladder suspension- Allow volume adjustability of stump. 2. Window/door suspension
TRAC SOCKET • Incorporates design elements from both the muenster and northwestern interfaces with more aggressive contouring of the anatomy to maximize load tolerant areas of the residual limb. • Compression anterior and slightly inferior to the epicondyles, specifically about the radial head on the lateral aspect. • On anterior/posterior plane, suspension is achieved by compression into the cubital fold and supra- olecranon region. • Relies on hydrostatic pressure.
Cont. • The position and degree of displacement of the skeletal substructure while wearing the TRAC interface are less affected during loading. • The TRAC addresses the deficits of previous designs by contouring five key areas: 1) the antecubital region, 2) the olecranon region, 3) the epicondylar region, 4) the distal radial region, and 5) the wrist extensor and flexor musculature
CRS SOCKET • Compression/Release Stabilized socket • Longitudinal depressions added in the socket walls with open release areas between the depressions that receive the displaced tissue . • Reduce motion of the underlying bony structures with respect to both the socket and the rest of the prosthesis. • The depressions and releases during cast- taking but only by radically changing the way casts are taken. • Requires selective pressure during cast-taking
Elbow Units for the Transradial Amputee Flexible Hinges • Attached proximally to the triceps pad and distally to the prosthetic forearm. • Permit the transmission of approximately 50% of the residual forearm rotation to the terminal device.
Rigid Hinges • Amputations at or above the mid forearm level obviate the possibility of transmitting active supination or pronation to the terminal device. At these levels of amputation the amputee must resort to manual prepositioning of the terminal device. • Types- 1. Single axis hinges 2. Polycentric hinges 3. Step-up hinges 4. Stump activated hinges
Single-axis hinges • Designed to provide axial (rotational) stability between the prosthetic socket and residual forearm. • Correctly aligned single-axis hinges should not restrict the normal flexion-extension range of motion of the anatomic elbow joint. • Available in both adult and child sizes.
Polycentric Hinges • Short transradial levels of amputation require that the anteroproximal trim line of the prosthetic socket be close to the elbow joint. With a high anterior socket wall, complete elbow flexion tends to be restricted by the bunching of soft tissues in the antecubital region. • Polycentric hinges help to increase elbow flexion by reducing the tendency for bunching of the soft tissues. • Available in adult, medium, and child sizes.
Step-Up Hinges • Amputations immediately distal to the elbow joint require a prosthetic socket with extremely high trim lines. • The use of step-up hinges requires that the prosthetic forearm and socket be separated. Consequently, protheses employing step-up hinges are frequently referred to as split-socket prostheses. • Amplify the excursion of anatomic elbow joint motion by a ratio of approximately 2:1. Sixty degrees of flexion of the anatomic elbow joint causes the prosthetic forearm (and terminal device) to move through a range of approximately 120 degrees of motion. • Adult, medium, child sizes.
Cont.
Stump-Activated Locking Hinge • Amputees with very high transradial levels of amputation are often unable to operate a conventional transradial prosthesis. • A split socket prosthesis is used. • Shoulder flexion on the amputated side flexes the mechanical elbow joint. • The residual limb is used only for locking and unlocking the mechanical elbow joint. • Adult and small size.
Cont.
Control Mechanism
Control Cable
Cont.
Bi-scapular abduction, shoulder flexion, elbow extension for terminal device opening.
Transradial Harness Systems • Figure 8 Harness:  Axillary Loop  O ring  Control Attachment Strap  Inverted Y strap • Figure 9 Harness: In case of self suspended sockets  Axillary loop  O ring  Control attachment strap • Shoulder Saddle with Chest Strap: For Heavy Duty Users  Shoulder Saddle  Chest Strap  Medial and Lateral Straps  Control Attachment Strap
Fig.8 Harness
Fig.9 Harness
Shoulder Saddle with Chest Strap
Bilateral Transradial Harnessing
Transhumeral and Elbow Disarticulation Prostheses Elbow disarticulation sockets- 1. Windowed socket 2. Screw-in socket 3. Flexible open frame 4. Flexible Inner bladder socket
Windowed Socket Screw-in Socket
Flexible Inner Bladder Socket
Flexible Open Frame Socket
TRANSHUMERAL DESIGN • OPEN SHOULDER ABOVE ELBOW SOCKET • CLOSED ENCAPSULATED DESIGN
Utah Dynamic Socket
Cont.
ACCI SOCKET • Inspired from Utah dynamic socket. • Reduction in the lateral trim line of the socket • An aggressive modification into the deltopectoral groove anteriorly • A flattened socket just inferior to the spine of scapula, • A firmly compressed anterior-posterior (AP) dimension for rotational control along the humeral axis . • A compressed medial-lateral (ML) dimension at the level of the axilla
Humeral AP clasp design • Wedge shaped cross-section in the midsection of the socket. • Humeral shaft lies in the angle of the wedge. • Flattening lateral aspect of the anterior and posterior socket walls creates the sides of the wedge.
CRS SOCKET • The anti-rotation wings are based on original design of Utah socket. • But this wings are smaller for added stability.
Outside-Locking Hinges • Elbow disarticulation and transcondylar levels of amputation • The standard units provide seven different locking positions throughout the range of flexion and come in adult, medium, and child sizes. • The heavy duty units provide five different locking positions and come in adult size only.
Inside Locking Hinges • Amputations through the humerus approximately 5 cm (2 in.) proximal to the elbow joint. • Inside-locking units permit the amputee to lock the elbow in any of 11 positions of flexion. • In addition, inside-locking units incorporate a friction-held turntable. • The turntable permits manual prepositioning of the prosthetic forearm as a substitute for external and internal rotation of the humerus.
Dual Control Cable System (Fair-Lead)
Body-powered Movements for Transhumeral Amputation- • Bi-scapular abduction and shoulder flexion for terminal device operation and elbow flexion/extension. • Shoulder depression, extension, internal rotation and abduction for elbow locking/unlocking. • Chest expansion, scapular abduction and shoulder flexion for terminal device operation and elbow flexion/extension. (In case of shoulder saddle with chest strap harness).
Fig.8 Harness
Modifications to Fig.8 Harness
Shoulder Saddle with Chest Strap
Bilateral Transhumeral Harnessing Systems
Shoulder Disarticulation Prostheses
Sockets • Conventional socket • Infraclavicular socket • X frame socket • Perimeter frame type socket • Micro frame-base socket
Infraclavicular socket • Does not enclose shoulder to support the weight of the prosthesis. • Relies on deltopectoral muscle group anteriorly And scapular region posteriorly. • Acromioclavicular complex free to move within the socket. • Less noticeable under the clothing.
X-Frame socket • Myoelectric use • Full contact socket for amputations at the shoulder level, • It permits the user to bend forward and to move the shoulder while maintaining good contact with electrodes. • It stabilizes the prosthesis against rotation at its superior and inferior borders • Covers far less surface area of the thorax for increased heat dissipation.
Perimeter frame type socket • Includes large windows or cutouts, in the anterior, posterior, and acromio-clavicular regions. • By moving the acromio-clavicular area or humeral neck inside the socket, the amputee can activate switches controlling electronic devices.
Micro frame-base socket
Bulkhead or Nonarticulated Locking Shoulder Joint (36 positions)
Ball and socket shoulder joint Shoulder swing joint
Body-powered movements for shoulder disarticulation- • Triple control cable systems • Contralateral scapular abduction for terminal device operation, mechanical shoulder and elbow flexion. • Chest expansion and shoulder elevation for elbow locking/unlocking. • Elbow locking and unlocking can also be achieved through chin/sound limb.
Chest strap with Waist belt harness system