Remotely Activated Piezoelectric Pump for Delivery of Biological Agents to the Intervertebral Disc and Spine

Abstract

A remotely activated piezoelectric pump for delivery of biological agents to the intervertebral disc and spine in order to achieve spinal fusion. A spinal pump is implanted on the vertebrae of a patient and a spinal cage is inserted in between two adjacent vertebrae after removal of the vertebrae disc. A piezoelectric motor drives the pump and pushes osteogenetic agent through the spinal cage and into a sponge disposed within the cage. The pump is charged by an external removable induction belt worn by the patient. Delivery duration and delivery frequency may be changed before implantation of the spine pump according to the specific needs of the patient. The current device employs a mathematical model that enables the regulation as well as attenuation of the bone fusion process by extending and generalizing the model to enhance and optimize the delivery of osteogenetic agent in a regulated manner.

Description

RELATED APPLICATIONS[0001]The present application is a divisional application of U.S. patent application Ser. No. 12 / 581,785, filed Oct. 19, 2009, which is incorporated herein by reference and to which priority is claimed under 35 USC 120.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention relates to the field of implantable drug delivery systems, specifically to a remotely activated piezoelectric pump for the controlled delivery of biological agents to the disc space and spine.[0004]2. Description of the Prior Art[0005]Scientists and spinal surgeons have demonstrated that a genetically produced protein, recombinant human bone morphogenetic protein-2, or rhBMP-2, has the ability to stimulate a patient's own cells to make more bone. This finding has obvious beneficial implications for the treatment of many bone fractures and bone defects. More importantly, though, rhBMP-2 can be tremendously beneficial to patients undergoing spinal fusion. RhBMP-2 will elimi...

AI Technical Summary

Benefits of technology

"The present invention is directed to the delivery of biological agents to the spine and intervertebral disc space for the treatment of degenerating discs and spine disorders. The invention provides an apparatus for constructing a remotely activated piezoelectric pump for delivery of biological agents to the intervertebral disc and spine. The apparatus includes a mathematical model that regulates the growth and differentiation of chondrocytes, the cells responsible for bone formation. The invention also allows for the controlled infusion of biological agents such as BMP-2 for up to 3 months, providing a more sustained infusion compared to other methods. The invention also includes a protective housing for the piezoelectric pump to withstand impacts and changes in pressure within the spinal column due to body motion. The invention also provides a method for directing the intradiscal delivery of BMP-2 to the specific fusion site and monitoring the progress of the fusion using mechanosensors. The invention also includes the concept of restoration, where the pump can be activated to deliver biological agents to the spine and intervertebral disc space to promote bone growth and spine fusion."

Problems solved by technology

Back pain not only has a profound effect on patients, it has an exceedingly high societal cost.

Back pain is the second most common cause of lost productive time of the pain disorders and results in the largest amount of total lost time.

It has been stated that of all medical conditions, back pain results in the most lost productivity.

As the disc degenerates hypertrophy is increased in order to support the body weight, eventually leading to back pain.

However, even with the use of iliac crest autograft and spinal fixation, the development of a biologic fusion—i.e., new bone formation at the fusion site, is not consistent.

Spinal fixation allows for short term mechanical stabilization, but lacks the capacity to produce a consistent biologic fusion.

Iliac crest autografts have associated morbidities related to the harvesting, including pain at the donor site.

DBM, however, is not capable of forming new bone (osteoinductive).

The posterolateral fusions appear to be effective with BMP-2 (although there was concern that it may actually work too well, and cause spinal stenosis).

The anterior cervical fusions were effective from the standpoint of cervical fusions, but often induced tracheal-esophageal swelling, leading to emergency intubations in some patients.

When the sponge is implanted, any squeezing or manipulation of the sponge results in loss of BMP-2, making the delivery technique inefficient. ii) BMP-2 half-life and time in circulation is short, usually less than a week, and an average fusion takes 3-6 months to complete. iii) Current BMP-2 has to be delivered at massive quantities compared to what is actually needed (milligram doses, as opposed to nanogram or mircogram doses of what is needed), costing health insurance and consumers up to $8,000 to $10,000 per implant.

Moreover, increased amounts of BMP-2 placed in the cervical or lumbar spine can lead to a tremendous amount of swelling. iv) BMP-2 delivery is not well directed, and is only passively absorbed.

As a result, BMP-2 placed posterolaterally has the potential of fusing too much, leading to spinal stenosis.

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