Materials Used for Making Orthoses
Orthoses are commonly made from a variety of materials including polypropylene, thermoplastics, fibreglass, foam, neoprene, and various composite materials, with material selection based on the specific orthotic application and patient needs. 1
Common Orthotic Materials
Plastic Materials
Polypropylene: Most widely used thermoplastic for orthoses due to its:
ABS (Acrylonitrile Butadiene Styrene):
- Suitable for moving parts like hinges 3
- More rigid than some other thermoplastics
PETG (Polyethylene Terephthalate Glycol):
- Used in 3D-printed orthoses 3
TPU (Thermoplastic Polyurethane):
- Highly flexible material
- Used for straps and components requiring elasticity 3
PP (Polypropylene):
Composite Materials
Fiber-reinforced composites:
- Kenaf composite has potential as an alternative material due to:
- Similar tensile strength to polypropylene
- Cost-effectiveness
- Abundance of raw materials
- Biocompatibility 4
- Kenaf composite has potential as an alternative material due to:
Carbon composites:
- High strength-to-weight ratio
- More expensive than other materials 4
Specialized Materials
UHMWPE (Ultra-High Molecular Weight Polyethylene):
- Used in joint replacement orthoses
- Enhanced wear resistance
- Reduced friction coefficients compared to other polymers 1
Mesh plastic sheets:
- "POROPLAST" - mesh plastic sheets combined in cross-like weave
- Provides good ventilation
- Comfortable in hot and humid conditions 5
Hybrid materials:
- Polypropylene covered with canvas fabric
- Provides similar functional benefits as conventional plastic AFOs
- Superior in terms of patient satisfaction and lighter weight 6
Material Selection Based on Orthotic Type
Foot Orthoses
- Custom-made insoles:
- Thermoplast materials for rigid support
- Neoprene for flexible applications 1
Ankle-Foot Orthoses (AFOs)
- Removable AFOs:
Knee Orthoses
- Frame components: PLA (Polylactic Acid) 3
- Moving parts: PLA or ABS 3
- Padding: PP (Polypropylene) 3
- Straps: TPU or PP 3
Hand/Wrist Orthoses
- Thumb base orthoses:
- Custom-made thermoplast for long-term wear
- Custom-made neoprene for night use 1
Clinical Considerations for Material Selection
Functional Requirements
- Weight-bearing needs: Select materials with appropriate strength-to-weight ratio
- Joint mobility: Choose materials that allow necessary movement while providing support
- Pressure distribution: Consider materials that can effectively distribute pressure
Patient Factors
- Climate considerations: In hot/humid environments, ventilative materials like mesh plastics may be preferred 5
- Skin sensitivity: Consider hypoallergenic materials for patients with sensitive skin
- Activity level: More durable materials for highly active patients
Emerging Trends in Orthotic Materials
- 3D printing technologies: Enabling customized orthoses using various polymer materials 3
- Beta-titanium alloys: For joint replacement orthoses, incorporating non-toxic elements like zirconium, tantalum, molybdenum, and niobium 1
- Diamond-like carbon coatings: Reducing wear and enhancing corrosion resistance in joint replacement orthoses 1
Pitfalls and Considerations
- Material selection should account for the specific orthotic application and patient needs
- Consider the trade-offs between rigidity, flexibility, weight, and durability
- Some materials like carbon composites offer excellent properties but at higher costs 4
- Proper fitting is crucial regardless of material choice to ensure effectiveness and patient compliance 1
- Long-term use of orthoses (at least 3 months) is recommended for optimal therapeutic benefit 1