Polymer Implantable Material Application Segments
Implantable devices are medical devices surgically placed within the body for diagnostic, monitoring, or therapeutic purposes, and are intended to remain in place for extended periods of time. Implantable applications encompass a wide range of medical devices and technologies introduced into the body through surgery or other interventions, serving various functions like drug delivery, disease monitoring, and enhancing quality of life.
Plastic materials can be, and are, used in a myriad of implantable medical devices. Implantable devices restore or enhance physical function, provide long-term medical management, and reduce the need for frequent medications or surgeries and are one of the fastest growing areas of medical science today.
The availability of plastic materials for implantable applications is increasing in recent years which gives device developers a chance to optimize (including miniaturization) their designs to a greater degree than in the past. We see this trend continuing into the future…which is great news for medical device developers.
Below is a synopsis of the types of implantable applications and the types of plastic materials that are candidates for specific application segments.
Note:
Biodurable: plastic materials implanted in the body that don’t break down
Non-durable: bioabsorbable plastic materials that eventually break down in the body
- Joint replacements: For hips, knees, shoulder, etc (UHMWPE, ketones, biodurable)
- Fracture fixation: Plates, screws, nails, pins (metal and biodurable)
- Bone Grafts/Substitutes: (ketones, PLA)
- Spinal implants: Used in spinal surgeries to stabilize the spine (ketones, TPU, biodurable)
- Craniomaxillofacial implants: Used in surgeries of the skull and face (ketones, biodurable)
- Candidate for 3D printing
- Sports medicine: Repair shoulder, foot, ankle, hand, wrist, knee: (metal, ketones, PLA, biodurable and non-durable)
- Pacemakers: Regulates hearts rhythm (metal for the casing, TPU or silicone for the leads)
- Cardiac defibrillators: Treats irregular heart rhythms (metal for the casing, TPU or silicone for the leads)
- Cochlear Implants: provide for a sense of sound to people with severe hearing loss (silicone, metals)
- Breast implants: Used for breast augmentation (shell is made of silicone, gel is made of silicone)
- Neurostimulators: Used to treat chronic pain or neurological conditions (metal for the casing, TPU or silicone for the leads)
- Implantable Infusion Pumps: Deliver medications continuously or intermittently over extended periods (metals for the casing and silicone, PLA or PLGA for the catheter and other components)
Metal Versus Plastics in Implant Applications
The choice between metals and plastics for medical implant applications depends on the specific application, desired properties, and cost considerations. Metals offer strength and durability, while plastics excel in biocompatibility, lightweight design, and cost-effectiveness. In many cases, the use of specialized polymers with metal-like performance is changing the landscape of medical implants, offering a wider range of options for manufacturers and healthcare professionals.
Plastic Advantages Over Metal:
- Excellent Biocompatibility: Medical-grade resins are designed to be biocompatible, minimizing the risk of adverse reactions.
- Lightweight and Compact: Plastics are generally lighter and more easily designed for compactness, which can be beneficial for patient comfort and device design.
- Cost-Effectiveness: Plastics are often less expensive than metals, especially for high-volume production.
- High Design Flexibility: Plastics offer greater design freedom, allowing for complex shapes and textures.
- Chemical Resistance: Plastics are often more resistant to chemicals and corrosion than metals.
- Durable polymers match cortical bone properties bone closely: Minimal stress cracking around the implant
- Minimal thermal and chemical conductivity: Increased stability in the body
- Color is similar to bone
- Chemical constituents are similar to normal biological tissue: Acceptance of the plastic long-term
- Hi corrosion resistance…assures functionality for long periods of time in the body
- Does not cause metal toxicity: Minimal health affects
- Design Flexibility: Metal is generally used for geometrically simple parts due to machining limitations
Metal Advantages Over Plastics:
- Strength & Durability: While some plastics are strong, they may not be as durable as certain metals…especially under high stress or temperature
- Sterilization: Some plastics may be more difficult to sterilize than metals
- Properties: Lower mechanical, tensile, shear strength, under fatigue loading
- Variation in chemical and structural changes
- Properties influenced by changes in environment and composition
- Surface Energy: Low attachment strengths for some polymers at the substrate interface
- Absorption: Can absorb nutrients and water from blood