Biodegradable bone plates and bonding systems
Inventors
McCarthy, Stephen • Weinzweig, Jeffrey
Assignees
NOVAPLAST Corp • University of Massachusetts Lowell
Publication Number
US-9173970-B2
Publication Date
2015-11-03
Expiration Date
2027-04-13
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Abstract
The invention relates to novel internal fixation devices, such as bone plates, generally and novel craniomaxillofacial bone plates more specifically and systems for bonding the same. More specifically, the invention relates to bone plates made of a polymer blend of (poly)lactic acid and Ecoflex as well as a novel hot-melt adhesive polymer blend of the same material.
Core Innovation
The invention provides novel internal fixation devices, such as bone plates, fabricated from a blend of polymers comprising polylactic acid (PLA) or PLA-based polymers and a biodegradable polyester-based polymer, such as Ecoflex. These internal fixation devices are particularly suited for craniomaxillofacial applications, but may also be used for hand fractures and osteotomies. The polymer blends can be manufactured as a single plate or as multiple components assembled with adhesives or the disclosed hot-melt bonding system.
The invention overcomes problems associated with traditional fixation systems that require the use of metallic materials or resorbable screws, which necessitate additional power equipment and increase surgical time, training, and cost. The new devices eliminate the need for screws and drilling by utilizing a melt-adhesive system to affix the fixation device directly to tissue, streamlining the fixation process. Porosity can be introduced into the plate structure, allowing for impregnation with biologically-active molecules and controlled, earlier resorption compared to existing systems.
The invention also discloses a polymer-based hot-melt adhesive system, made from the same PLA and polyester-based polymers, for securely bonding the fixation device to tissue without secondary fixation devices such as screws or pins. Additionally, the invention provides methods for preparing, sterilizing, and storing the fixation devices, methods for direct plate-less tissue bonding using the same adhesive blend, and methods for constructing selectively porous plates that enable tuning of resorption rate and bioactive molecule delivery.
Claims Coverage
There are three independent inventive features covered by the independent claims of this patent.
Bonding a porous, bioactive plate to tissue using melt adhesion without secondary fixation devices
A method of bonding an internal fixation device, particularly a porous, bioactive plate, to tissue by: - Placing the device in contact with tissue to be fixed. - Applying energy (such as heat) to melt at least a portion of the device. - Allowing the melted portion to harden so the device is fixed to tissue, without use of a secondary fixation device (such as a screw, pin, or additional plate). The fixation device is specifically described as being a porous, bioactive plate.
Bonding bone tissue segments with a meltable, bioabsorbable polymer adhesive without secondary devices
A method for bonding bone tissue segments by: - Melting a bioabsorbable polymer adhesive composed of a first polymer or co-polymer (including polylactic acid) and a second polymer or co-polymer (including polyester) in a co-continuous phase. - Applying the melted adhesive to at least one bone tissue segment such that it contacts bone tissue. - Affixing the bone tissue segment(s) to one or more other portions of bone tissue, without use of a secondary fixation device (such as a plate, pin, or screw).
Affixing a porous, bioactive internal fixation device to tissue without drilling or perforating
A method of bonding an internal fixation device, specifically a porous, bioactive plate, to tissue by: - Placing the device in contact with tissue to be fixed. - Applying energy to melt at least part of the device. - Allowing the melted portion to harden, affixing the device without drilling or perforating through tissue. The method does not require drilling or perforating through the tissue for fixation.
The inventive features are centered on the use of PLA/polyester-based polymer blends to produce porous, bioactive internal fixation plates and associated polymer-based adhesives, enabling direct thermal bonding to tissue without screws or drilling, and the methods for their use in tissue and bone fixation.
Stated Advantages
Eliminates the need for screw fixation and drilling, simplifying and expediting intra-operative plate application.
Reduces the need for power equipment, thereby lowering cost, operating room time, and the need for additional staff training.
Facilitates controlled and earlier resorption of bone plates (within 3–6 months), better matching the bone healing timeline compared to existing systems.
Allows impregnation of plates with biologically-active molecules due to the introduction of controlled porosity.
Offers improved mechanical properties over PLA alone by blending with Ecoflex, including superior stiffness, toughness, and elongation to break.
The bonding system enables fixation in situations where use of plates, pins, or screws is not feasible, offering plate-less fixation options.
Documented Applications
Use as internal fixation devices in craniomaxillofacial surgery, including for congenital deformities, fractures, and post-tumor resection reconstruction.
Bone plates for treating hand fractures.
Plates used in conjunction with osteotomies.
Direct bonding of bone tissue segments (plate-less technique), especially where traditional approaches (plates, pins, screws) are contraindicated or unfeasible, such as near articular surfaces, epiphyseal growth plates, non-displaced/minimally displaced fractures, severely comminuted fractures, and elderly patients with inadequate bone stock.
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