Method and apparatus for implanting a hydrogel prosthesis for a nucleus pulposus
Inventors
Vresilovic, Edward • Keane, Michael • Schaer, Thomas Peter • Arthur, Amy • Singhatat, Wamis
Assignees
Synthes GmbH • DePuy Spine LLC • DePuy Synthes Products Inc • ReGelTec Inc
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Publication Number
US-7850730-B2
Publication Date
2010-12-14
Expiration Date
Abstract
An instrument for inserting an elongated hydrogel prosthesis into an intervertebral disc includes an insertion cannula that is inserted through the annulus fibrosus of an intervertebral disc to provide access to the nucleus region of the disc, an elongated hydrogel prosthesis packaged within a tubular container adapted to be coupled to a proximal end of the insertion cannula, and a source of fluid pressure adapted to be coupled to a proximal end of the tubular container. Auxiliary instruments for use in convenient insertion of the insertion cannula through the nucleus pulposus and providing for a complete and controlled passage of the hydrogel prosthesis through the insertion cannula are provided in a kit with the insertion cannula. A sizing apparatus for determining the volume of prosthesis to be inserted includes a catheter or cannula capable of being inserted through the insertion cannula into the nucleus region of the intervertebral disc and having at its distal end a balloon capable of being inflated within the intervertebral disc with a measurable volume of a fluid in order to determine the amount of hydrogel prosthesis to be injected.
Core Innovation
The invention relates to implanting an injectable hydrogel prosthesis within an intervertebral disc. A method uses guidewires and a prosthesis insertion cannula to advance through tissue surrounding an intervertebral disc, through an annulus fibrosus, and into a nucleus pulposus region, leaving an open channel into the nucleus pulposus region after guidewire removal.
The invention determines a volume within the intervertebral disc to be filled by the hydrogel prosthesis using an inflatable highly compliant balloon. The balloon is inserted in a collapsed state, inflated to a fully distended state when inflated with about 3 psi, and further expanded until the disc is adequately pressurized to restore natural mechanical properties at a balloon pressure between 20 psi to 40 psi.
The measured volume is used to select a predetermined amount of hydrogel prosthesis, which is pressurized with a source of fluid pressure to force the hydrogel through the delivery lumen into the nucleus pulposus region. Related embodiments include an access incision, a sizing balloon, and optional intradiscal pressure transducer monitoring to terminate injection when a target pressure is reached.
Claims Coverage
The partial content includes four independent claims. Across these claims, the coverage centers on disc access with cannulas and guidewires, balloon-based determination of intervertebral disc target volume using a highly compliant balloon, and insertion or injection of a measured volume of a hydrogel prosthesis matched to the measured balloon volume.
Guidewire and cannula path to nucleus pulposus region
Advancing guidewires and a prosthesis insertion cannula through tissue surrounding an intervertebral disc, through an annulus fibrosus, and into a nucleus pulposus region, and leaving an open channel into the nucleus pulposus region after guidewire removal.
Balloon sizing to restore natural mechanical properties and measure fluid volume
Inserting an inflatable highly compliant balloon, inflating it to a fully distended state when inflated with about 3 psi, continuing to a balloon pressure between 20 psi to 40 psi at which the intervertebral disc is adequately pressurized to restore natural mechanical properties, and measuring the volume of fluid required to reach that pressure.
Pressurized storage tube delivering a predetermined hydrogel amount matching measured balloon volume
Coupling a storage tube containing a predetermined amount of hydrogel prosthesis substantially corresponding to the measured volume of fluid, applying fluid pressure, and forcing the hydrogel through the delivery lumen into the nucleus pulposus region.
Access incision cannula injection with balloon sizing and matched prosthesis volume
Forming an access incision, inserting a cannula into the intervertebral disc, determining disc size with a sizing balloon, selecting a tube containing a volume of hydrogel prosthesis at least substantially equal to the inflated volume of the sizing balloon, and inserting the hydrogel prosthesis through the cannula.
Collectively, the claims cover disc-access and delivery using cannulas and guidewires, together with balloon-based sizing at a target pressure between 20 psi to 40 psi and insertion or injection of a hydrogel prosthesis volume at least substantially equal to the measured balloon-inflation volume.
Stated Advantages
Restore the natural mechanical properties of the intervertebral disc by adequately pressurizing the intervertebral disc at a balloon pressure between 20 psi to 40 psi.
Achieve a predetermined hydrogel prosthesis amount that substantially corresponds to the measured volume of fluid required to inflate the balloon to the target pressure.
Documented Applications
Implanting a hydrogel prosthesis within an intervertebral disc by creating an open channel into a nucleus pulposus region and forcing the hydrogel through a delivery lumen.
Implanting an injectable prosthesis within an intervertebral disc by accessing the disc, pressurizing it with a highly compliant balloon, measuring required fluid volume, and injecting the measured volume of fluid of the injectable prosthesis into the intervertebral disc.
Injecting a hydrogel prosthesis into an intervertebral disc using an access incision and cannula, where disc size is determined with a sizing balloon and the prosthesis volume is selected to match the inflated balloon volume.
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