upper limb prosthesis (pmr)

UPPER LIMB PROSTHESISUPPER LIMB PROSTHESIS

Astha PatniAstha Patni

IntroductionIntroduction• 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

• A successful 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

• 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

• Reasons for upper limb amputation – 0-15 years: Correction of a congenital

deformity or tumor – 15-45 years: Trauma, tumor – 60 years: Rare ; tumor or medical

disease

AMPUTATION LEVELSAMPUTATION LEVELS• Transphalangeal amputation: Resection of the

thumb or fingers at distal interphalangeal (DIP), proximal interphalangeal (PIP), or metacarpophalangeal (MCP) levels, or at any level in between

• Transmetacarpal amputation: Resection through the metacarpals

• Transcarpal amputation: Resection through the carpal bones

• Wrist disarticulation: Transection between the carpals and radius/ulna

AMPUTATION LEVELSAMPUTATION LEVELS• Transradial amputation: Below-elbow amputation

(may be classified as long, medium, or short)

• Elbow disarticulation: Transection through the elbow joint

• Transhumeral amputation - Above-elbow (Standard length is 50-90% of humeral length.)

• Shoulder disarticulation: Transection through the shoulder joint

• Interscapulothoracic disarticulation (forequarter): Amputation removing the entire shoulder girdle (scapula and all or part of the clavicle

TYPES • Body powered or conventional• External powered or electric • Cosmetic or passive• Hybrid

Body powered or Body powered or conventionalconventional

• Pros– low cost– Moderately lightweight– Most durable

• Cons– Most body movement to operate– Most harnessing– Least satisfactory appearance

External powered or electricExternal powered or electric• Pros

– Moderate or no harnessing– Least body movement to operate– Moderate cosmesis– More function – proximal levels

• Cons– Heaviest – Most expensive– High maintenance– Limited sensory feedback

Cosmetic or passiveCosmetic or passive• Pros

– Most lightweight– Best cosmesis– Least harnessing

• Cons– High cost if custom made– Least function

Upper limb prosthesisUpper limb prosthesis• Prosthetic components

– Terminal devices– Wrists– Elbows– Shoulders

• Socket • Suspension

Terminal devicesTerminal devices• Functional activities of hand

– Non prehensile– Prehensile

Terminal devicesTerminal devices• Non prehensile

– Touching, feeling, pressing down with fingers, tapping, vibrating the cord of musical instrument, lifting or pushing with hand

• Prehensile– Precision grip (i.e. pincher grip), Tripod

grip, Lateral grip, Hook power grip, Spherical grip

Terminal devicesTerminal devices• Active

– Hooks– Functional hands– Activity specific devices

• Passive– Cosmetic hands

Hook / Hand

Mechanical Electrical

VO VC Electrical Myoelectric

Digital Proportional

PassiveActive

Terminal devicesTerminal devices• Lack sensory feedback• Limited mobility and dexterity

• Hand – three-jaw chuck• Hook – lateral pinch

Terminal devicesTerminal devices• VO

– Practical– In closed position, by springs– Patient pulls the cable to open– Prehensile force – spring

• VC– Physiological– In open position– Patient pulls the cable to close– Prehensile force – patient – Greater proprioceptive input

Voluntary-Closing HooksVoluntary-Closing Hooks

• APRL hook developed by the Army Prosthetics Research Laboratory

Voluntary-Opening Hook Voluntary-Opening Hook Terminal DevicesTerminal Devices

• 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

. Voluntary-opening hook-. Voluntary-opening hook-type terminal devicetype terminal device

Voluntary-Closing HandsVoluntary-Closing Hands

Otto Bock system hands

Voluntary-Opening HandsVoluntary-Opening 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

ELECTRIC TERMINAL DEVICESELECTRIC TERMINAL DEVICES

Hand like shape

• Otto Bock System Electric Hands

• Steeper Electric Hands

Not having hand like shape

• Otto Bock System Electric Greifer

• Hosmer NU-VA Synergetic Prehensor

• Steeper Powered Gripper

• NY-Hosmer Prehension Actuator

Otto Bock System Electric Hand (left) and Steeper Electric Hand (right). A with mechanism covered by handlike shells; B with internal mechanism exposed.

• A "palmar" and B lateral views of the Steeper Powered Gripper (left), Otto Bock System Electric Greifer (center), and Hos-mer NU-VA Synergetic Prehensor (right).

Myoelectric controlMyoelectric control

• tranradial myoelectric prosthesis (Otto Bock type) The system uses two myoelectric sites on the residual limb. the signal flow in a two-site, two-function myoelectric hand prosthesis

Activity specific devicesActivity specific devices• Farming• Construction• Cooking• Photography • Sports: golf, fishing, skiing

Cosmetic glovesCosmetic gloves• Digit, hand, extend

till elbow• Custom made

silicone cosmetic covers – expensive and difficult to maintain

Prosthetic wristsProsthetic wrists• Provide receptacle for connecting

terminal device• Pronosupination or flexion based on

functional activities of patient

Prosthetic wrists Prosthetic wrists Types• Mechanical

– Pronosupination• Friction (Can rotate)• Quick-disconnect• Spring-assisted (B/L amputee)

– Flexion (B/L amputee , longer side)• Spring-assisted internal or external

Prosthetic wristsProsthetic wrists• Electric (B/L trans-humeral)

– Pronosupination• Myoelectric (B/L amputee)• Switch control

Friction wrist units. Friction wrist units.

Round and oval configurations Round and oval configurations of constant friction wrist unitsof constant friction wrist units

Quick-change wrist unitsQuick-change wrist units

Flexion wrist unitsFlexion wrist units

Electric wrist unitsElectric wrist units

• The Otto Bock Electric Wrist Rotator. The rotator, shown alone at the bottom, mechanically and electrically interfaces with the quick-disconnect adaptor of the System Electric Hand or Greifer

Prosthetic elbowsProsthetic elbowsClassification• Body-powered elbow

– External with or without spring assisted flexion (elbow disarticulation)

– Internal, with or without spring assisted flexion

– Internal, with rotating turntable (allows internal/ external rotation)

Prosthetic elbowsProsthetic elbows• Externally powered elbow

– Digital switch control– Proportional switch control– Digital myoelectric control– Proportional myoelectric control

• Passive elbow– Manual lock

Elbow units Elbow units Flexible hinges Rigid hinges

Elbow Elbow Polycentric hinges Step up hinges

ELBOW UNITELBOW UNIT

OUTSIDE LOCKING INSIDE LOCKING

Electrical powered elbowsElectrical powered elbows

• Boston Elbow,• NY-Hosmer Electric Elbow, • Utah Arm. These elbows differ from one another

in mechanical configuration, drive mechanism, and control options.

Prosthetic socketsProsthetic socketsFunctions

– Comfortable residual limb – prosthesis interface

– Efficient energy transference to the prosthesis

– Secure suspension of the prosthesis– Adequate cosmesis

Prosthetic socketsProsthetic sockets• Wood

– Chronic edema– Trophic skin changes

• Plastic – Total contact– Decreased weight– Increased durability

Prosthetic socketsProsthetic sockets• Two layers

• Inner-contoured to the residual limb• External- gives length and shape

• Components are attached to external layer

Prosthetic socketsProsthetic sockets• Process

– Negative impression of residual limb (POP)– Positive mold– Modify positive mold (remove from

pressure tolerant and add to pressure sensitive)

– Transparent / check socket – Trial fit and modify– New positive mold– Final socket

Negative mold

Positive mold

socket

Various socketsVarious sockets• Wrist disarticulation socket• long Below elbow socket• Short below elbow socket• Very short below elbow socket [ Split sockets] Muenster sockets

• Elbow disarticulation socket• Standard above elbow socket• Short above elbow socket• Shoulder disarticulation socket• Forequarter amputation socket

Suspension systemsSuspension systems• Functions

– Suspension – securing prosthesis to residual limb

– Control of prosthesis / terminal devices• Types

– Harness• Figure of 8 (traditional)• Chest strap (proximal amputation)• Shoulder saddle (proximal amputation)

Harness

Suspension systemsSuspension systems• Self suspension

– Condylar– Muenster (Self suspending; Not

preferred in B/L transradial amputation)– Northwestern

• Semisuction– Hypobaric– Semisuction

• Suction– Full suction– Silicone sock

Suction suspension preferred for Tranhumeral amputee with normal contrlateral limb

• Sock• Interface between residual limb and

socket• Layers adjustable to volume changes• Protect skin and improve hygiene• Socks with special silicone band and

socket with one way valve are used in semisuction type of suspension systems

Silicone suction suspensionSilicone suction suspension• Kristinsson in 1986• Improved suspension with negative

atmospheric pressure• Reduction of shear forces on skin• Allows volume adjustment with

residual limb girth changes• Simplified donning, better elbow

range of motion, lighter

Silicone suction suspensionSilicone suction suspension• Silicone sleeve with distal

attachment pin that fits into shuttle lock mechanism in socket

• Rolls silicone liner directly over skin after spraying alcohol

• Socks over silicone to improve fit

Silicone suction suspensionSilicone suction suspension• Patients with problems of skin

integrity– Skin grafting for burns, – degloving injury, – insensate skin (diabetes, scleroderma),– adhesive scar tissue

Control mechanismsControl mechanisms• Body powered (harness)

– Scapular abduction– Chest expansion– Shoulder depression, extension,

abduction, flexion– Elbow flexion, extension

• Discomfort• Less cosmetic

MECHANICS OF THE BELOW-ELBOW (TRANSRADIAL) CONTROL SYSTEM

• Glenohumeral joint flexion for operating a terminal device.

HEAVY-DUTY HEAVY-DUTY TRANSRADIAL HARNESS TRANSRADIAL HARNESS

BILATERAL TRANSRADIAL BILATERAL TRANSRADIAL HARNESSHARNESS

TRANSHUMERAL CONTROL TRANSHUMERAL CONTROL

SYSTEMSYSTEM Two types of

control cable

1.Elbow flexion/terminal device control cable

2.Elbow lock control cable

Trans humeral hareness controlTrans humeral hareness control

The operating sequence of the two The operating sequence of the two cable systems cable systems

• Tension applied to the elbow flexion/terminal device control cable causes the elbow to flex;

• When the desired angle of elbow flexion is achieved, the rapid sequential application and release of tension on the elbow lock control cable locks the elbow

• With the elbow locked, the reapplication of tension on the elbow flexion/terminal device control cable permits operation of the terminal device

SHOULDER DISARTICULATION SHOULDER DISARTICULATION HARNESSHARNESS

Control mechanismsControl mechanisms• Externally powered prostheses• Electric motors inside prosthesis for

wrist rotation / elbow flexion or extension

• Motors controlled by switches, myoelectric signals, acoustic signals

Control mechanismsControl mechanismsSwitch

• Inside or outside socket• Activated on contact by amputee

Control mechanismsControl mechanismsMyoelectric controls

• Electrical activity generated during muscle contraction to control flow of energy from a battery to a motor in prosthetic device

• Antagonistic muscles in distal portion with normal voluntary activity


• Electrodes inside socket detect muscle action potentials, amplify them to turn on motor which brings about movements

• Single channel: two electrode sites, one for each function (open & close terminal device)

• Multi-channel: single electrode, amplitude of signal determines function


• High cost• Low reliability• Heavy (motors, batteries)

– India: electrodes rust quickly because of sweat, electronic circuits fail due to dust / sweat

Prostheses by level of Prostheses by level of amputationamputation


Partial hand• Prosthesis not necessary• Surgical reconstruction – opposition – for

prehension with proprioception


• Wrist disarticulation– Distal radial-ulnar articulation preserved

for prono-supination– Socket: tapered and flattened distally

forming an oval shape– Wrist unit: thin, to minimize length– Cosmetically: trans radial


Transradial amputationClassification (based on length)

• Very short (<35%): rigid elbow hinges• Short (35-55%): <60º pronosupination,

flexible elbow hinges• Long (55-90%): 60-120 º

pronosupination, flexible elbow hinges

Below elbow prosthesis


Transradial amputation with decreased elbow ROM• Polycentric elbow joints or split socket

with step-up hinges used to provide additional flexion

• Decreased elbow flexion power


Elbow disarticulation• Sockets: flat and broad distally (like

epicondyles)• External elbow joint with cable operated

lock in medial joint• Suspension: figure of 8, shoulder saddle,

chest strap• Control system: 2 cables, one to lock the

elbow, other opens terminal device or flexes elbow


Transhumeral amputationClassification (based on length of

humerus)• Very short (<30%)• Short (30-50%)• Standard (50-90%)


Transhumeral amputation• Sockets:

– Residual limb greater than 35% - proximal trimline within 1cm of acromion, suspension with figure of 8, shoulder saddle, or chest strap

– Residual limb smaller than 35% - proximal trimline 2.5cm medial to acromion, suspension with chest strap or suction socket


Transhumeral amputation• Elbow joint

– Internal elbow joint• Preferred • Level of amputation 4 cm or more proximal from

epicondyles• Allows passive internal / external rotation• Elbow spring-lift assist available

– External elbow joint• Distal amputation• Maintains elbow center with contralateral side


Transhumeral amputation• Control system

– Dual cable (like elbow disarticulation)

Above elbow prosthesis

Shoulder disarticulation and Shoulder disarticulation and forequarter amputationforequarter amputation

• Socket– Extends to thorax– Open –frame socket to decrease weight

and heat• Similar to transhumeral + shoulder

unit

Bulk headFlex / ext

Universal


• Control: – Triple cable system– One for elbow flexion when opposite

humerus is flexed– Second cable opens terminal device

with chest expansion– Third cable locks / unlocks elbow with

chin / opposite hand


• Externally powered prosthesis preferred

• Passive cosmetic prosthetic restoration in some patients

upper limb prosthesis (pmr)

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