What is Medical Polyoxymethylene?

Polyoxymethylene (POM), commonly known by the trade names Delrin or Acetal, is a semicrystalline thermoplastic material belonging to the polyoxymethylene family. It is a light-colored polymer that has high strength and rigidity even at elevated temperatures, together with self-lubricating properties. POM has exceptional machinability and dimensional stability.

Characteristics and Properties

Some key characteristics and properties of POM that make it suitable for medical applications include:

- High strength and rigidity: POM has high tensile strength and flexural modulus comparable to engineering thermoplastics like Medical Polyoxymethylene.

- Wear resistance: Its self-lubricating properties impart excellent wear resistance, making it suitable for bearing surfaces.

- Chemical resistance: POM has good resistance to a wide range of chemicals, reactions and sterilization methods.

- Low friction: Its low coefficient of friction allows smooth articulation of moving parts.
- Biocompatibility: POM is biocompatible and passes USP Class VI biological tests. It does not leach or bond to tissue during implantation.

- Low moisture absorption: POM absorbs minimal moisture which is important to retain mechanical properties over the lifetime of an implant.

- Machinability: It can be easily machined, molded, tapped or formed to close tolerances for complex parts.

- X-ray transparency: POM is radiolucent and does not interfere with medical imaging like CT scans.

Applications in Surgery

Given the above properties, POM has found widespread application in surgical tools and medical devices:

Surgical Instruments

Implants and Prosthetics

Load-bearing POM components are used in total joint replacement implants for hips, knees and shoulders. Dental prosthetics and bone fixation plates also use POM. Its mechanical properties are well-suited for long-term implants.

Diagnostic Medical Polyoxymethylene

Components in medical imaging equipment like X-ray tables, CT and MRI machines use POM for its non-ferromagnetism and non-artifact properties. Dialysis machine parts also employ POM for its durability in aqueous environments.

Orthopedic Tools

Cutting guides, drills and other orthopedic tools use POM parts that do not decay over multiple sterilization cycles. Surgeons value POM’s tactile feel and machinability for intricate bone procedures.

Dental Materials

Denture bases, repairs, models and impression trays make use of POM’s abrasion-resistance. Its self-lubricity allows smooth articulation during lateral jaw movements for superior patient comfort.

Advantages in Manufacturing

POM polymer stock offers distinct advantages in manufacturing medical components:

- Injection molding enables mass production of complex parts with tight tolerances.
- CNC machining produces precise intricate details for complex instruments and tools.
- Aqueous chemical etching permits fabrication of miniature parts for advanced devices.
- 3D printing of POM powder allows low-volume customized production.
- Single-use medical devices use low-cost POM components.
- Secondary operations like tapping, coating and assembly are easily done.
- Superior lot traceability meets stringent medical industry protocols.

POM components are commonly used in forceps, clamps, retractors and other handheld surgical instruments. Its self-lubricity prevents instrument parts from binding or seizing up. Complex, small instruments can be precisely machined from POM stock.