Polymer sleeve for inhibiting stem wear and improving taper-lock in modular and non-modular orthopedic implants and the fabrication and processing thereof
Inventors
Prabhu, Balaji • Wood, Andrew • Dadsetan, Mahrokh • Karau, Andreas • Patel, Harsh • Knebel, Marc • BANDI, Suneel
Assignees
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Publication Number
US-11771801-B2
Publication Date
2023-10-03
Expiration Date
Abstract
The present invention comprises a polymer and/or polymer composite based sleeve to be fitted between an extended body, such the neck, trunnion, and/or stem of a hip implant, and a receiving body, such as a femoral head in a hip implant, that reduces wear, decreases toxic material from wear debris, enhances the mechanical connection of the extension and receiving body, reduces or eliminates impingement with receiving body, delocalize stress concentrations, and may also serve as a modifying junction between an extension and receiving body of unmatched size. The polymeric based sleeve presently disclosed comprises an inert and/or biologically favorable material which may be used in its virgin form or contain biocompatible additives. In order to best match patient and implant requirements, modifications may be made in the length, thickness, composition, as well as the presence of a taper, or lack thereof, in order to be compatible with existing devices.
Core Innovation
The invention provides a polymeric sleeve for an implant, where the polymeric sleeve includes a distal end and a proximal end. The sleeve height measured from the distal end to the proximal end is between 5 and 50 mm, and the angle of the taper is adjustable between 5 and 7 degrees.
The polymeric sleeve is configured to address issues at a taper junction and to reduce fretting corrosion and metal debris, including heavy metal ions, while mitigating impingement and delocalizing stress concentrations. The polymeric sleeve is described as improving taper-lock and mechanical connection and stability, and as mitigating catastrophic failure.
The polymeric sleeve is described with selectable polymer materials and composite options, including polyaryletherketone, polyetheretherketone, and polyethylene, with polyethylene including PE, UHMWPE, crosslinked PE, and Vitamin-E infused PE. The sleeve can include additive material amounting to up to 50% by weight of the sleeve’s polymeric material, and is described with geometric configurations such as tapered or non-tapered sleeves and fully-bored or partially-bored sleeves.
Claims Coverage
The independent claim defines a polymeric sleeve with three core inventive constraints: sleeve height (5 to 50 mm), an adjustable taper angle (5 to 7 degrees), and a polymeric sleeve structure having a distal end and proximal end. Dependent claims further add wall thickness limits, additive loading, polymer selections, polyethylene subtypes, and comparative performance attributes versus a non-polymeric sleeve.
Polymeric sleeve with defined distal and proximal ends and sleeve height
A polymeric sleeve for an implant comprising a polymeric material, the polymeric sleeve comprises a distal end and a proximal end, wherein the height measured from the distal end to the proximal end of the sleeve is between 5 and 50 mm.
Adjustable taper angle between 5 and 7 degrees
The polymeric sleeve has an angle of the taper, wherein the angle of the taper is adjustable between 5 and 7 degrees.
Sleeve wall thickness between 0.2 and 20 mm
The polymeric sleeve has an internal and external surface with thickness measured from the internal surface to the external surface between 0.2 and 20 mm.
Additive material amount up to 50% by weight
The polymeric sleeve includes an additive material amounting to up to 50% by weight of the sleeve’s polymeric material.
Polymer selection including polyaryletherketone and polyethylene
The polymeric sleeve specifies a polymeric material selected from polyaryletherketone, polyetheretherketone, and polyethylene, and the implant is a joint implant including an extended body and a receiving body.
Polyethylene subtypes including PE, UHMWPE, crosslinked PE, and Vitamin-E infused PE
The polymeric sleeve is defined such that the polyethylene includes PE, UHMWPE, crosslinked PE, Vitamin-E infused PE, and other polymerization material and compounds of the parent polymer.
Improved performance attributes compared to a non-polymeric sleeve
A polymeric sleeve is claimed to have improved wear resistance, mechanical properties, coefficient of friction, taper lock, improved biological response, or improved wear resistance compared to a non-polymeric sleeve.
Overall claim coverage centers on a polymeric sleeve defined by a distal end/proximal end with a 5 to 50 mm height and a taper angle adjustable between 5 and 7 degrees. Dependent claims further specify wall thickness, additive loading, polymer selections including polyethylene subtypes, and comparative performance relative to a non-polymeric sleeve, including taper lock and biological response.
Stated Advantages
Reduce fretting corrosion and metal debris, including heavy metal ions.
Improve taper-lock and mechanical connection and stability.
Mitigate impingement.
Delocalize stress concentrations.
Mitigate catastrophic failure.
Improve wear resistance, mechanical properties, and coefficient of friction.
Improve biological response relative to a non-polymeric sleeve.
Documented Applications
Use in orthopedic modular and non-modular implants, including hip taper junctions between a stem/trunnion/neck and a femoral head.
Comparative performance support using finite element analysis and mechanical testing (pull-off force stability after static loading, cyclic loading, and creep hold).
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