Upper Limb Prosthetics

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Upper Limb Prosthetics - Limb Loss Lowdown

  • Prosthesis: Artificial device replacing a missing body part. Orthosis: Device supporting/correcting a body part or its function.

  • Goals of UL Prosthetics: Restore function (grasp, reach), cosmesis, enable Activities of Daily Living (ADLs).

  • Amputation Levels & Fitting Implications:

    • Forequarter: Loss of entire shoulder girdle; complex fitting, often cosmetic or body-powered hook.
    • Shoulder Disarticulation (SD): Through shoulder joint; socket covers shoulder, suspension can be challenging.
    • Transhumeral (TH/AE): Above elbow; requires elbow unit, good for myoelectric control.
    • Elbow Disarticulation (ED): Through elbow joint; humeral condyles aid suspension, external elbow hinges.
    • Transradial (TR/BE): Below elbow; common, good prosthetic function, some forearm rotation preserved.
    • Wrist Disarticulation (WD): Through wrist; preserves distal radioulnar joint (DRUJ), allows some forearm rotation.
    • Transcarpal: Through carpal bones; partial hand, often custom silicone restoration.
    • Digital: Finger/thumb amputation; can be cosmetic or functional (e.g., opposition post).

Upper Limb Amputation Levels Diagram

⭐ The transradial amputation is the most common major upper limb amputation level, offering good prosthetic function and versatility with various prosthetic designs.

Upper Limb Prosthetics - Armamentarium Array

  • Socket:
    • Design: Total contact for optimal load distribution.
    • Materials: Thermoplastic (e.g., polyethylene), laminated resins.
  • Suspension Systems:
    • Harness (e.g., Figure-of-8), suction (valve/sleeve), anatomical (supracondylar), osseointegration.
  • Control Systems:
    • Body-powered: Cables transmit body motion.
    • Myoelectric: EMG sensors detect muscle signals.
  • Terminal Devices (TDs):
    • Hooks: Durable, precise, functional. Hands: Cosmetic, varied grip.
    • Types: Passive (cosmetic), Body-powered (Voluntary Opening - VO / Voluntary Closing - VC), Externally powered (myoelectric).

    ⭐ Voluntary opening (VO) hooks are generally more durable and require less effort to operate for sustained grip than voluntary closing (VC) hooks.

  • Wrist Units:
    • Friction control, quick-disconnect, flexion/extension, rotation units.
  • Elbow Units:
    • Locking mechanisms (manual/automatic), passive (friction), active (body/external power).
  • Shoulder Units:
    • For high-level amputations (disarticulation/forequarter); passive or specialized joints.

Above-elbow upper limb prosthesis components

Upper Limb Prosthetics - Pick Your Power-Arm

TypeMechanism of ActionControl MethodEnergy SourceAdvantagesDisadvantages
PassiveStatic, cosmetic appearanceNoneNoneLightweight, good cosmesisNo active function
Body-PoweredCables & harness, body movement drivenGross body motionUser's bodyDurable, proprioception, lower costHarness discomfort, high effort
MyoelectricEMG signals from residual musclesMuscle contractionBatteryIntuitive control, strong grip forceHeavy, expensive, needs maintenance
HybridCombination of body & external powerMixedMixedOptimizes function/weight/costCan be complex to operate/maintain

⭐ Myoelectric prostheses offer more natural control and grip strength but are heavier, more expensive, and require more maintenance than body-powered options.

Upper Limb Prosthetics - Fit, Function, Fixes

  • Prosthetic Prescription Principles:
    • Consider: Level of amputation, patient's functional needs, vocation, age, cognitive ability, personal preference, and cost.
  • Key Prosthetic Checkout Points (Static & Dynamic Assessment):
    • Fit: Snug socket, no pistoning, pressure distribution.
    • Comfort: Absence of pain, wearable for daily activities.
    • Function: Smooth operation of terminal device and controls.
    • Alignment: Anatomically correct joint positioning, good posture.
    • Cosmesis: Patient satisfaction with appearance.
  • Common Stump & Prosthetic Complications:
    • Stump Issues: Skin breakdown, edema, neuromas, phantom limb pain/sensation.
    • Prosthetic Issues: Mechanical failure, socket discomfort, harness issues.
  • Prosthetic Training & Rehabilitation Goals:
    • Master donning/doffing, control strategies, functional task integration.
    • Achieve maximal independence in Activities of Daily Living (ADLs).

⭐ The 'golden period' for fitting an upper limb prosthesis is generally considered to be within the first 30-90 days post-amputation for optimal functional outcomes.

High‑Yield Points - ⚡ Biggest Takeaways

  • Transradial amputations (below-elbow) are the most common upper limb level.
  • The Krukenberg operation creates a functional pincer from forearm bones (radius and ulna).
  • Myoelectric prostheses are controlled by EMG signals from residual limb muscles.
  • Terminal devices: Hooks offer superior function; hands provide better cosmesis.
  • Proper socket fit is crucial for comfort, suspension, and prosthetic control.
  • Shoulder disarticulation prostheses often require an external power source.
  • Phantom limb pain is a frequent complication managed with multimodal therapy, not solely by prosthesis use.

Practice Questions: Upper Limb Prosthetics

Test your understanding with these related questions

Extensive surgical debridement, decompression or amputation may be indicated in the following clinical setting except

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Flashcards: Upper Limb Prosthetics

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_____ due to discomfort and poor appearance is the most common complication of bracing.

TAP TO REVEAL ANSWER

_____ due to discomfort and poor appearance is the most common complication of bracing.

Poor compliance

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