Upper Limb Prosthetics

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).

⭐ 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.

Upper Limb Prosthetics - Pick Your Power-Arm

⭐ 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.