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
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Publication Number
US-12570028-B2
Publication Date
2026-03-10
Expiration Date
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 disclosed invention relates to a method for forming a unitary article from at least two powder blends selected from polymer powder, polymer powder with porogen powder, polymer powder with inorganic particle powder, or polymer powder with porogen powder and inorganic particle powder. The powder blends differ in the content of the polymer powder, porogen powder, inorganic particle powder, or combinations thereof, so that the resulting article contains regional differences in material composition and/or porosity.
The powder blends are dispensed into at least one mold, and each powder blend is compacted into two or more parts having complementary mating surfaces. The complementary mating surfaces are assembled to form an article assembly and compression molded to form a unitary article free from discernible boundaries between portions derived from the two or more parts.
Porogen is leached from the unitary article after compression molding, and optional formation of additional features is described. In representative embodiments, the unitary article is an implantable medical device, and the document includes representative compositional and mechanical/fatigue/subsidence testing results.
Claims Coverage
The document contains three independent claims. Each independent claim centers on assembling complementary mating parts that include porogen, compression molding into a unitary article that is free from discernible boundaries, and leaching porogen, with one claim further requiring at least two distinct powder blends compacted into complementary parts.
Differently composed powder blends compacted into complementary mating parts
Provide at least two powder blends selected from polymer powder; polymer powder with porogen powder; polymer powder with inorganic particle powder; and polymer powder with porogen powder and inorganic particle powder, such that the at least two powder blends differ in content of the polymer powder, porogen powder, inorganic particle powder, or a combination thereof; dispense each into at least one mold; compact each into two or more parts with complementary mating surfaces.
Compression molding into a unitary article without discernible boundaries
Assemble the two or more parts with complementary mating surfaces to form an article assembly and compression mold the article assembly to form a unitary article.
Porogen leaching from the unitary article
Leach porogen from the unitary article.
Unitary article free from discernible boundaries derived from assembled parts including porogen
Assembling two or more parts with complementary mating surfaces to form an article assembly, at least one of the two or more parts with complementary mating surfaces including at least one porogen; compression molding the article assembly to form a unitary article free from discernible boundaries between portions derived from the two or more parts; optionally forming additional features; and leaching the at least one porogen from the unitary article.
Unitary article portions formed from powder blend preforms
At least one of the two or more parts with complementary mating surfaces is formed by dispensing a powder blend into at least one mold, the powder blend including at least one polymer powder, at least one porogen in powder form, and optionally at least one inorganic particle powder, and compacting the powder blend in the at least one mold to form at least one preform.
Porogen-containing complementary mating part assembly compression molded into a boundary-free unitary article
Assembling two or more parts with complementary mating surfaces to form an article assembly, at least one including at least one porogen; compression molding the article assembly to form a unitary article free from discernible boundaries between portions derived from the two or more parts; optionally forming additional features; and leaching the at least one porogen from the unitary article.
Across the independent claims, the core inventive coverage is the use of porogen-containing complementary mating parts, optionally formed from different polymer/porogen/inorganic powder blends, compression molded into a unitary article that is free from discernible boundaries between portions derived from the assembled parts, and leaching porogen to form the final unitary article.
Stated Advantages
Designed to prevent distortion and nonuniformities caused by differing powder compaction/densification behaviors during single-step molding.
Produces a unitary article free from discernible boundaries between portions derived from the assembled parts.
Documented Applications
The unitary article is a biomedical implant, and the described approach is used for forming thermoplastic biomedical implants.
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