Implantable medical device with varied composition and porosity, and method for forming same

Inventors

Farris, Jeffery A • Brown, Kevin Lee • Snell, Douglas B. • Roeder, Ryan K. • MESSMAN, Mark G.

Assignees

Happe Spine LLC

Abstract

A method for forming a thermoplastic body having regions with varied material composition and/or porosity. Powder blends comprising a thermoplastic polymer, a sacrificial porogen and an inorganic reinforcement or filler are molded to form complementary parts with closely toleranced mating surfaces. The parts are formed discretely, assembled and compression molded to provide a unitary article that is free from discernible boundaries between the assembled parts. Each part in the assembly has differences in composition and/or porosity, and the assembly has accurate physical features throughout the sections of the formed article, without distortion and nonuniformities caused by variable compaction and densification rates in methods that involve compression molding powder blends in a single step.

Core Innovation

The invention relates to forming a unitary article by providing at least two powder blends that differ in content of polymer powder, porogen powder, and inorganic particle powder. The powder blends are dispensed into at least one mold and compacted into two or more preforms, where the preforms are then machined into two or more parts with complementary mating surfaces and assembled before compression molding.

In particular, at least two parts are discretely formed from powder blends by compression molding or cold pressing, followed by machining each part to provide interfitting machined parts with complementary mating surfaces. The interfitting machined parts are assembled and compression molded to provide the unitary article consisting of materials from the at least two powder blends, free from discernible boundaries between portions derived from the interfitting machined parts.

The method is directed to implantable articles and includes using different powder blends to create at least one porous preform and a porous region in the unitary article. Porogen can be leached from the unitary article to form porous structures, and compression molding is applied at a specified pressure to prevent volumetric expansion during heating while preserving accurate geometry.

Claims Coverage

The provided partial content contains three independent claims. The independent claims cover methods for forming a unitary article from at least two differing powder blends by discretely forming and machining parts or preforms with complementary mating surfaces, assembling them, and using compression molding to obtain a unitary article without discernible boundaries, including porogen leaching or porous-region preservation.

Across the independent claims, the core coverage is the fabrication of a unitary article or implantable unitary article from multiple powder blends by discretely forming and machining components to create complementary or interfitting mating surfaces, assembling them, and compression molding to eliminate discernible boundaries while preserving or creating porous regions derived from porogen-containing powder blends.

Stated Advantages

Documented Applications