Fixation device with electromagnetic pump
An assembly for promoting interstitial fluid flow can include an implant having first and second electrodes, a control unit, and one or more magnets. The implant can be disposed at a selected site of a subject, and the control unit can be electrically coupled to the first and second electrodes and can provide power to the first and second electrodes to generate an electric field at the selected site. The one or more magnets can be disposed adjacent to the selected site and can generate magnetic field in a direction orthogonal to the electric field in order to drive electrically conductive interstitial fluid flow at the selected site.
1 . An assembly for promoting interstitial fluid flow, comprising:
an implant configured to be disposed at a selected site of a subject, the implant comprising spaced apart first and second electrodes;
a control unit electrically coupled to the first and second electrodes, the control unit configured to provide power to the first and second electrodes to generate an electric field at the selected site, and measure an electrical impedance between the first and second electrodes; and
one or more magnets disposed adjacent to the selected site, the one or more magnets configured to generate a magnetic field in a direction orthogonal to the electric field in order to drive interstitial fluid flow at the selected site at a specified flow rate and direction, and wherein the control unit is configured to adjust voltage applied to the first and second electrodes to adjust the electric field based on the measured electrical impedance to adjust the flow rate of the interstitial fluid flow.
2 . The assembly of claim 1 , wherein the selected site is a fracture in a subject's bone, wherein the implant and the control unit are implanted within the subject at the selected site, and wherein the implant is configured to be placed in contact with the subject's bone and span the fracture, with the first and second electrodes disposed on either side of the fracture.
3 . The assembly of claim 1 , wherein the one or more magnets are disposed in a wearable harness that is configured to be worn by the subject, external and adjacent to the selected site.
4 . The assembly of claim 1 , wherein the control unit is disposed on the implant.
5 . The assembly of claim 1 , wherein the control unit comprises a microcontroller, a power supply, and a power regulator, and wherein the control unit is connected to the first and second electrodes by wires.
6 . The assembly of claim 5 , wherein the control unit further comprises:
relays which are configured to switch between sensing and stimulating modes, wherein in the sensing mode a signal from the first and second electrodes provides feedback as to a status of a tissue at the selected site as it heals, and wherein in the stimulating mode the first and second electrodes supply the electric field for generating the interstitial fluid flow; and
a network analyzer which is configured to measure the electrical impedance between the first and second electrodes, for determination of the status of the tissue.
7 . The assembly of claim 1 , wherein the one or more magnets includes a pair of magnets that are placed at a perpendicular orientation relative to the first and second electrodes.
8 . A method of treating a subject in need thereof, comprising disposing the assembly of claim 1 at the selected site and generating the electric field orthogonal to the magnetic field at the selected site for a predetermined duration of time.
9 . The method of claim 8 , wherein generating the electric field comprises applying pulsed input voltage to the first and second electrodes for the predetermined duration of time at a non-50% on/off pulsed amplitude cycle.
10 . The method of claim 8 , wherein the subject has a bone fracture, a laceration, or a shallow tissue injury at the selected site.
11 . The method of claim 8 , wherein the predetermined duration of time is in a range of 15-25 minutes, and further comprising generating the electric field orthogonal to the magnetic field at the selected site for the predetermined duration of time starting at 14-21 days following implantation of the implant at the selected site and at a frequency of two to three times per week.
12 . The method of claim 8 , further comprising switching from a stimulating mode where the electric field is generated by the first and second electrodes to a sensing mode where a signal from the first and second electrodes is obtained by the control unit and processed to determine an impedance of a tissue at the selected site for a determination of a healing status of the tissue.
13 . An assembly for promoting interstitial fluid flow, comprising:
a bone fixation implant comprising:
a bone fixation plate configured to be coupled to a bone of a subject at a location of a fracture;
first and second electrodes that are spaced apart from one another; and
a control unit electrically coupled to the first and second electrodes, wherein the control unit is configured to actuate the first and second electrodes to generate an electric field at the fracture and adjust the generated electric field based on an electrical impedance measured between the first and second electrodes; and
one or more magnets disposed adjacent to the fracture, wherein the one or more magnets are configured to generate a magnetic field in a direction orthogonal to the electric field in order to drive interstitial fluid flow at the fracture at a specified flow rate and direction for bone healing.
14 . The assembly of claim 13 , wherein the bone fixation plate comprises a plurality of apertures, each aperture configured to receive a fastener for fixing the bone fixation plate to the bone of the subject.
15 . The assembly of claim 13 , wherein the control unit comprises a microcontroller, a power supply or coil, a power regulator, relays which are configured to switch between sensing and stimulating modes, and a network analyzer which is configured to measure the electrical impedance of the bone at the fracture, between the first and second electrodes, for determination of a status of the bone, wherein in the sensing mode a signal from the first and second electrodes provides feedback as to the status of bone at the fracture as it heals, and wherein in the stimulating mode the first and second electrodes supply the electric field for generating the interstitial fluid flow at the specified flow rate and direction.
16 . The assembly of claim 13 , wherein the one or more magnets includes two magnets disposed on an outside of a body of the subject, adjacent to the fracture.
17 . The assembly of claim 16 , wherein the two magnets are spaced apart from one another on or in a wearable harness that is configured to be positioned around the body of the subject, at a region of the fracture of the bone to which the bone fixation implant is coupled.
18 . An assembly for promoting interstitial fluid flow, comprising:
a bone fixation implant comprising:
a bone fixation plate configured to be coupled to a bone of a subject at a location of a fracture;
first and second electrodes that are spaced apart from one another; and
a control unit electrically coupled to the first and second electrodes, wherein the control unit is configured to actuate the first and second electrodes to generate an electric field at the fracture; and
one or more magnets disposed adjacent to the fracture, wherein the one or more magnets are configured to generate a magnetic field in a direction orthogonal to the electric field in order to drive interstitial fluid flow at the fracture, wherein the bone fixation plate comprises an elongated main body and first and second extension members extending in a same direction from opposite sides of the main body such that the first and second extension members are spaced apart from one another.
19 . The assembly of claim 18 , wherein the first electrode is disposed on or in the first extension member and the second electrode is disposed on or in the second extension member, and wherein the first and second extension members extend from a central portion of the main body.
20 . The assembly of claim 18 , wherein the control unit is disposed on or in a central portion of the main body.