Anatomy of Upper Limb Orthosis

Anatomy-Related Principles: Upper Limb Orthosis

• The upper extremity is complex, encompassing shoulder, arm, forearm, wrist, and hand.
• Bones, muscles, nerves, and soft tissues interact to enable a wide range of movement.
• Disruptions to this intricate system can lead to dysfunction, including pain, weakness, and reduced range of motion (ROM).

Arches of the Hand

• The hand has three interconnected arches crucial for a wide range of motion.
• The proximal transverse arch is formed by distal carpal bones and a taut volar carpal ligament.
• The mobile distal transverse arch is located at the level of the metacarpal heads, adapting based on CMC joint mobility.
• The longitudinal arch, spanning from metacarpals to distal phalanges, is maintained by intrinsic hand muscles.
• Disruption to the longitudinal arch, potentially from ulnar nerve injuries, can cause a claw-like deformity.

Palmar Creases

• The palm's surface features creases formed by fibrous connections attaching thick skin to underlying structures.
• These creases serve as anatomical guides when designing orthosis patterns.
• Careful clearing of the creases during orthosis fabrication is crucial for unrestricted range of motion at the metacarpophalangeal (MCP) joints.
• Excessive clearing can impact the orthosis' mechanical efficiency.

Wound Healing Principles & Tissue Response to Stress

• Orthoses are frequently utilized to aid in healing injuries.
• The specific type of orthosis used depends on the stage of tissue healing.

Inflammatory Phase

• Characterized by increased blood flow, redness, heat, swelling, and pain.
• Rest is prioritized, and immobilization devices (orthoses) protect the injured area.

Fibroplasia/Proliferation Phase

• New granulation tissue forms, collagen and blood vessels develop, and the wound closes.
• Mobilization orthoses provide controlled stretching to promote tissue growth and improve range of motion (PROM).

Scar Maturation/Remodeling Phase

• Scar tissue reorganizes and strengthens.
• Orthoses assist in mobilizing joints to improve scar tissue alignment and flexibility.

Categorization of UL Orthoses

• The American Society of Hand Therapists' Splint Classification System (ASHTSCS) offers a comprehensive splint categorization system.
• This system aids in communicating about splints amongst hand therapists, physicians, and healthcare professionals.

Splint Classification System (Expanded)

• Splints/orthoses are categorized by location (articular or non-articular).
• Further categorized by direction (immobilization, mobilization, restriction, torque transmission).

Location (Articular/Non-articular)

• Articular orthoses affect joints using three-point pressure systems. They can immobilize, mobilize, restrict movement, and transmit torque.
• Non-articular orthoses use two-point pressure to stabilize/immobilize body segments (long bones). The term "non-articular" should always be included in the orthosis's name.

Location (further categorized)

• Articular orthoses are further named after the joint(s) affected (e.g., elbow orthosis, thumb metacarpal orthosis).
• Non-articular orthoses are named after the affected long bone (e.g., ulna orthosis, humerus orthosis).

Direction (e.g. immobilization)

• Orthoses, with this classification, are categorized based on the movement they restrict/enable.
• Immobilization orthoses (static) secure joints to aid in healing, without any active movement.
• Mobilization orthoses aid in joint movement.

Effective Orthotic Design

• Orthoses should be simple, easy to don/doff, and avoid unnecessary components.
• Joints should not be included unnecessarily, unless it improves leverage or mechanical advantage.
• A professional appearance is prioritized, with smooth edges and rounded corners.
• Materials used should ensure durability.

Wrist Orthoses (forearm-based):

• Circumferential supports typically immobilize fractures/maintain alignment without significant joint restriction.

Problem Solution in Orthosis Use

• Orthosis use should not excessively press on skin, leading to color changes and temperature alterations.
• Skin should be protected using perforations and/or lightweight materials to mitigate pressure-related breakdown.
• Proper use/fitting should be monitored for edema reduction (movement of fluid in the body).

Improper Positioning of Joints

• Carefully assess joint positioning during orthosis use with attention to wrist, thumb, and finger placements.
• Orthoses should not hinder natural/needed movement or cause skin irritation.
• Potential complications, including compromised cognition or allergic reactions to materials, need careful attention during orthosis use.

Appropriate considerations when using orthotics

• Pay attention to how orthosis affects the joints (and placement), and the general well-being of the patient.