ASTM F648-21 Standard Specification for Ultra-High Molecular Weight Polyethylene Powder and Manufactured Form for Surgical Implants

The standard “ASTM F648-21 Standard specification for ultra-high molecular weight polyethylene powder and manufactured forms for surgical implants” developed by the American Society for Testing and Materials (ASTM) covers ultra-high molecular weight polyethylene powder (UHMWPE) and manufactured forms designed for use in surgical implants.

The requirements of this standard apply to UHMWPE in two forms. One is pure polymer powder, the second is any form produced from this powder from which a finished product is then manufactured. This standard addresses material properties and does not apply to the finished implant that has been packaged and sterilized. Furthermore, the requirements of this standard do not apply to pure UHMWPE powder or manufactured forms that have been intentionally crosslinked or blended with other additives, such as antioxidants.

In this standard, the biological response to polyethylene in soft tissue and bone has been well characterized by clinical use history and laboratory studies.

For the purposes of this standard, the following terms and definitions apply:

• Processed form refers to any bulk form of UHMWPE produced from pure polymer powder used in the manufacturing process of surgical implants prior to packaging and sterilization. This form results from the application of heat and pressure to the pure polymer powder and the material properties of this form are subject to the applicable requirements of this specification. In current practice, this includes ram-extruded rods or molded blocks that are processed to the final product form, or a molded shape that is subsequently trimmed.
• The general property refers only to the property of the pure polymer determined by its chemical composition and structure.
• The morphology index expresses the ratio of the total number of type A and B indications to the total surface area examined in cm2.
• A Type A unfused flake is a gauge with a substantially complete peripheral black border and a white center that is visible under the conditions described in the standard.
• A Type B unfused flake is an indicator with a partially circumferential black border following 50 percent to 99 percent of the flake's circumference, visible under the conditions described in the standard.
• Pure polymer powder refers to the form of UHMWPE obtained from the powder manufacturer before it is converted into a bulk form.

Pure UHMWPE polymer is a homopolymer of ethylene in accordance with the standard “ASTM D4020-18 Standard specification for ultra-high molecular weight polyethylene molding and extrusion materials”. The resin type and solution viscosity number requirements are listed in the table in the standard.

When a 300 g sample is prepared and examined in accordance with the standard, there should be no more foreign material particles than specified in the table. To promote uniformity between different polymer powder batches, concentration limits for trace elements are specified and listed in the table. UHMWPE powder described in this standard shall be manufactured in accordance with a certified quality management system.

No stabilizers, antioxidants or processing aids shall be added to the pure polymer powder during the production of the manufactured UHMWPE polymer. No stabilizers, antioxidants or processing aids shall be added to the manufactured form during the production of the final implant. When evaluated according to this standard, no more than ten particles of foreign matter shall be visible on the surface when visually examined by a person with normal or fully corrected vision when 5000 cm2 is evaluated. When evaluated during consolidation process verification, the calculated morphology index and the total surface area examined shall be reported. Evaluation of the morphology index during routine monitoring of a validated manufacturing process is not required because alternative test methods in this standard, such as density and mechanical properties as required in the table included in the standard, already provide reasonable, redundant assurance of successful consolidation.

Among the numerous testing, measurement, analysis and evaluation studies that our organization has carried out for businesses in various sectors, our organization also provides testing services defined in the standard “ASTM F648-21 Standard specification for ultra-high molecular weight polyethylene powder and its manufactured form for surgical implants” with its trained and expert staff and advanced technological equipment.