# Upper Limb Prosthetic Options and Training

## Introduction

Upper limb amputation accounts for approximately **20% of all amputations** in the United States, with trauma being the leading cause. Unlike lower limb prosthetics where the primary goal is ambulation, upper limb prosthetics must address complex prehension, proprioception, and cosmesis. Prosthetic rejection rates remain high (20-50%), making appropriate prescription and training essential.

## Amputation Levels

**Partial hand/finger**: Most common level; often functional without prosthesis. **Wrist disarticulation**: Preserves pronation/supination. **Transradial**: Below elbow; most successful prosthetic outcomes. **Elbow disarticulation**: Long lever arm; limits elbow unit options.

**Transhumeral**: Above elbow; requires prosthetic elbow and terminal device. **Shoulder disarticulation and forequarter**: Highest complexity; lowest prosthetic use rates.

## Prosthetic Categories

### Body-Powered Prostheses
**Cable-operated** via figure-of-nine harness system. Terminal devices: **Voluntary-opening** (most common) or voluntary-closing hooks. Advantages: Durable, proprioceptive feedback through cable, lower cost, lighter weight. Disadvantages: Limited grip force, harness discomfort, restricted range of motion. Preferred for heavy manual labor and outdoor activities.

### Myoelectric Prostheses
**EMG signals** from residual muscles control motorized components. Two-site (biceps/triceps) or pattern recognition control. Advantages: Improved cosmesis, greater grip force, no harness required. Disadvantages: Heavier, expensive, requires battery charging, moisture-sensitive. Preferred for light to moderate activities, cosmesis priority.

### Activity-Specific Prostheses
Sport-specific terminal devices (cycling, swimming, golf). Work-specific tools (adapted for vocational tasks). Musical instrument adaptations.

### Passive/Cosmetic Prostheses
Custom silicone restorations with realistic appearance. No active function; body image and symmetry benefits. Lowest rejection rate of all prosthetic types.

| Prosthetic Type | Control Method | Advantages | Disadvantages | Best For |
|----------------|---------------|-----------|---------------|----------|
| Body-powered | Cable/harness | Durable, feedback, lightweight, low cost | Limited grip, harness discomfort | Heavy labor, outdoor use |
| Myoelectric | EMG signals | Better cosmesis, grip force, no harness | Heavy, expensive, moisture-sensitive | Light activity, cosmesis |
| Activity-specific | Varies | Task-optimized | Limited to specific activities | Sports, vocation |
| Passive/Cosmetic | None | Realistic appearance, low rejection | No active function | Body image, symmetry |

![Comparison of body-powered and myoelectric transradial prostheses with terminal device options](images/upper-limb-prosthetic-types.jpg)

## Advanced Prosthetic Technologies

### Pattern Recognition Control
**Multiple EMG electrode arrays** classify muscle patterns. Intuitive simultaneous multi-joint control. Commercially available systems (e.g., Coapt pattern recognition). Requires structured training and calibration.

### Targeted Muscle Reinnervation (TMR)
Residual nerves transferred to denervated muscle segments. Creates **additional EMG control sites**. Improves myoelectric control and may reduce phantom/neuroma pain. Ideally performed at time of amputation.

### Osseointegration
Titanium implant directly anchored in bone. Eliminates socket; improves proprioception (osseoperception). Requires staged surgical procedure and strict rehabilitation protocol.

### Sensory Feedback Systems
Vibrotactile or electrotactile feedback for grip force. Emerging neural interface technologies. Improves functional performance and embodiment.

![Targeted muscle reinnervation concept showing nerve transfer sites for enhanced myoelectric control](images/targeted-muscle-reinnervation.jpg)

## Prosthetic Training Protocol

### Pre-Prosthetic Phase
Residual limb desensitization and shaping. ROM and strengthening of proximal joints. One-handed techniques for ADL independence. Mirror therapy for phantom limb management. Psychosocial counseling and peer support.

### Initial Prosthetic Training
**Controls training**: Learning to activate terminal device (cable pull or EMG signals). Repetitive grasp-release practice with graded objects. Isolated component control before integrated use. Donning and doffing independence.

### Functional Training
**Bimanual coordination** activities (prosthesis as assist hand). ADL tasks: Eating, dressing, grooming, writing. Kitchen and household management. Driving evaluation with adaptive equipment. Vocational tasks and return-to-work planning.

### Advanced Training
Sport and recreational activities. Fine motor tasks for myoelectric users. Community integration activities. Maintenance and troubleshooting of prosthetic components.

## Outcome Measures

**Assessment of Capacity for Myoelectric Control (ACMC)**. Box and Blocks Test. Southampton Hand Assessment Procedure (SHAP). Disabilities of the Arm, Shoulder, and Hand (DASH). Trinity Amputation and Prosthesis Experience Scales (TAPES).

![Prosthetic training progression from controls training to functional bimanual activities](images/upper-limb-prosthetic-training.jpg)

## Complications and Challenges

**Prosthetic rejection**: Higher in upper limb than lower limb (20-50%). Overuse injuries in the intact contralateral limb. Socket discomfort and skin breakdown. Neuroma pain and phantom sensations. Psychosocial adjustment and body image concerns.

## Key Clinical Pearls

1. **Prosthetic rejection rates** are highest for transhumeral and shoulder disarticulation levels; early fitting (within 30 days) improves acceptance. 2. Body-powered prostheses provide superior proprioceptive feedback through cable tension, making them preferred for tasks requiring force modulation. 3. Pattern recognition myoelectric control offers more intuitive multi-joint operation compared to traditional two-site control. 4. Successful upper limb prosthetic use depends more on quality of training and patient motivation than on device sophistication.

## References

1. Resnik L, Meucci MR, Lieberman-Klinger S, et al. Advanced upper limb prosthetic devices: implications for upper limb prosthetic rehabilitation. *Archives of Physical Medicine and Rehabilitation*. 2012;93(4):710-717.
2. Carey SL, Lura DJ, Highsmith MJ. Differences in myoelectric and body-powered upper-limb prostheses: systematic literature review. *Journal of Rehabilitation Research and Development*. 2015;52(3):247-262.
3. Dumanian GA, Potter BK, Mioton LM, et al. Targeted muscle reinnervation treats neuroma and phantom pain in major limb amputees. *Annals of Surgery*. 2019;270(2):238-246.
4. Biddiss EA, Chau TT. Upper limb prosthesis use and abandonment: a survey of the last 25 years. *Prosthetics and Orthotics International*. 2007;31(3):236-257.