Anatomic tissue-engineered osteochondral implant and method for fabrication thereof
Inventors
STOECKL, BRENDAN D. • Mauck, Robert L. • ZLOTNICK, HANNAH • Farrell, Megan • Miller, Liane • Steinberg, David
Assignees
University of Pennsylvania Penn • US Department of Veterans Affairs
Publication Number
US-11633879-B2
Publication Date
2023-04-25
Expiration Date
2041-01-19
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Abstract
A method for forming a prosthesis comprising a bone-like portion and a cartilage-like portion can comprise additively manufacturing a first positive mold in accordance with a portion of a first three-dimensional model of a portion of a bone. A first negative mold can be formed from the first positive mold. The bone-like portion can be created within the first negative mold. A second positive mold of the bone and a cartilage can be additively manufactured from a second three-dimensional model. A portion of the second three-dimensional model can correspond to a portion of the first three-dimensional model. A second negative mold can be formed from the second positive mold. The bone-like portion can be positioned in the second negative mold so that the second negative mold and the bone-like portion can define a cartilage space that can be filled with a material to form the cartilage-like portion of the prosthesis.
Core Innovation
The invention relates to a method for forming a prosthesis comprising a bone-like portion and a cartilage-like portion. The method includes additively manufacturing a first positive mold based on at least a portion of a first three-dimensional model of a bone, forming a first negative mold from that positive mold, and creating the bone-like portion within the first negative mold. Then, a second positive mold of the bone and cartilage is additively manufactured from a second three-dimensional model, where a portion corresponds to the first model. A second negative mold is formed from this second positive mold. The bone-like portion is positioned in the second negative mold so that together they define a cartilage space, which is then filled with a material to form the cartilage-like portion of the prosthesis.
The problem being solved addresses issues related to trapeziometacarpal (TMC) osteoarthritis, a common condition in middle and older aged adults, where conservative treatments often fail and surgical interventions may sacrifice grip strength and cause disfigurement. The invention provides a prosthesis that anatomically replicates bone and cartilage surfaces, aiming to replace damaged cartilage and bone tissue with a structure that mimics a healthy, natural joint. The bone-like portion is configured to promote bone integration and ingrowth, while the cartilage-like portion replicates cartilage morphology and function.
Claims Coverage
The patent includes one independent claim defining a method with multiple inventive features related to forming a prosthesis with bone-like and cartilage-like portions using specific molding and material steps.
Method for forming prosthesis using additive manufacturing of molds and molding techniques
The method involves additively manufacturing a first positive mold from a three-dimensional bone model, forming a first negative mold, creating a bone-like portion within the first negative mold, additively manufacturing a second positive mold from a second three-dimensional model including bone and cartilage, forming a second negative mold, positioning the bone-like portion in the second negative mold to define a cartilage space, and filling that space with material to form the cartilage-like portion.
Use of polydimethylsiloxane (PDMS) for forming negative molds
The first negative mold is formed from the first positive mold using PDMS, which is resistant to solvents and optically transparent.
Creation of bone-like portion using polycaprolactone (PCL) dissolved in chloroform
The bone-like portion is formed by filling the first negative mold with a mixture comprising PCL dissolved in chloroform followed by solvent evaporation to produce a porous foam structure.
Incorporation of sodium chloride crystals and subsequent salt leaching to create porosity
The mixture includes sodium chloride crystals with defined size, and after molding, the prosthesis is soaked in water to dissolve the salt, creating pores to promote bone ingrowth.
Inclusion of bone-promoting factors in bone-like portion
The bone-like portion contains factors such as hydroxyapatite or similar to promote bone integration.
Use of hydrogel for cartilage-like portion with on-demand crosslinking
The cartilage space is filled with a hydrogel, such as methacrylated hyaluronic acid (meHA), which is subsequently irradiated (e.g., UV light) to crosslink and solidify the cartilage-like portion.
Inclusion of stem cells in the cartilage-like hydrogel
The hydrogel can be cell-laden, containing between 10 million and 100 million cells per milliliter, including autologous mesenchymal stem cells or similar cells.
Creation of three-dimensional models from medical imaging
Both first and second three-dimensional models are created from imaging data captured via CT scan, MRI, or laser scan of ex vivo samples, allowing anatomical accuracy and customization.
Modification and editing of three-dimensional models to remove clinical damage and add fixation features
The models can be edited to remove holes or osteophytes and to add fixation features such as keels or through-holes, enabling secure prosthesis attachment to remaining bone tissue.
The invention covers a comprehensive method for producing anatomically accurate osteochondral prostheses by combining advanced three-dimensional modeling, additive manufacturing of molds, fabrication of bone-like portions with porous polymer structures, and formation of cartilage-like portions with cell-laden hydrogels. The method includes steps for anatomical data acquisition, mold formation using PDMS, and material processing that together provide a biocompatible, functional prosthesis designed for integration and regeneration of osteochondral tissues.
Stated Advantages
Enables fabrication of anatomically-shaped osteochondral constructs that closely mimic native bone and cartilage.
Provides a prosthesis designed to promote bone integration and tissue ingrowth through controlled porosity.
Utilizes optically transparent and chemically resistant negative molds, allowing photocrosslinking of cartilage hydrogels in complex geometries.
Facilitates on-demand crosslinking of hydrogels containing live stem cells, improving cartilage tissue formation.
Allows customization of the prosthesis to either the original or an idealized bone shape, accounting for individual anatomical variations and defects.
Documented Applications
Replacement of damaged osteochondral tissue in trapeziometacarpal (TMC) osteoarthritis affecting human patients.
Fabrication of prostheses for animal model bones, such as porcine accessory carpal bones, to study device performance and joint biomechanics.
Repair or replacement of articular surfaces including but not limited to femoral condyles, tibial plateaus, humeral heads, scapular glenoid, carpal bones, talus, and calcaneus joints.
Use in pre-clinical large animal testing for osteochondral implant evaluation and surgical implantation.
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