The present disclosure relates to devices used in orthopedic surgical procedures and methods of inserting those devices in a medical patient. Specifically, the present disclosure relates to devices that can be used to correctly position a pair of adjacent interspinous processes and methods of inserting these devices between the pair of adjacent interspinous processes.
Surgical techniques have been developed to treat spinal stenosis, a condition of the spine characterized by a narrowing of the spinal canal. With spinal stenosis, the spinal canal narrows and pinches the spinal cord and nerves, causing pain in the back and legs. One such surgical technique developed is to separate a pair of adjacent vertebrae and insert an interspinous implant between the interspinous processes to maintain the desired separation between the vertebrae. However, the steps required to separate the pair of adjacent vertebrae and to insert the interspinous implant can be time consuming and difficult since different instruments are often used to perform each step.
As with any surgery, one consideration when performing surgery to insert an interspinous implant between adjacent vertebrae is the size of the incision that is required to allow introduction of the implant. Minimally invasive techniques are generally preferred since the patient usually requires less recovery time than with a traditional or open surgery. For a minimally invasive surgery, a small incision in the patient is created to form an implantation profile in which instruments and an interspinous implant are inserted into a patient. Next, the surgeon using the instruments must carefully separate the pair of adjacent vertebrae and insert the interspinous implant between the interspinous processes on the pair of vertebrae.
Working through a small incision to insert instruments and an interspinous implant between a pair of vertebrae requires particular devices as well as abundant care on the part of the surgeon.
For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the claims is thereby intended, such alterations and further modifications in the illustrated devices, and such further applications of the principles of the disclosure as illustrated therein, being contemplated as would normally occur to one skilled in the art to which the disclosure relates.
Referring generally to
Implant 30 is formed of a flexible material which allows legs 34, 36, 38, and 40 to bend during insertion of implant 30 between a pair of interspinous processes and to flex back to implant 30's original shape after insertion. As illustrated in
As illustrated, body portion 32 has a thickness slightly greater than legs 34, 36, 38, and 40. In other forms, body portion 32 has a thickness equal to legs 34, 36, 38, and 40. Body portion 32 includes a pair of curved surfaces 33 to engage the interspinous processes. As illustrated, legs 34, 36, 38, and 40 each form a triangular or wedge shape; however, in other forms, legs 34, 36, 38, and 40 can be shaped differently. By non-limiting example, legs 34, 36, 38, and 40 can be rectangle or curved shapes.
Implant 30 may be formed from a wide variety of biocompatible materials that can undergo reversible elastic deformation. Examples of such materials include elastic or rubbery polymers, hydrogels, or other hydrophilic polymers, or composites thereof. Some suitable elastomers include silicone, polyurethane, copolymers of silicone and polyurethane, polyolefins, neoprene, nitrile, vulcanized rubber, and combinations thereof. In other embodiments, implant 30 is made of a metal that can undergo reversible elastic deformation, such as shape-memory metals or nickel-titanium.
The nature of the materials employed to form implant 30 should be selected so that implant 30 has sufficient load-bearing capacity. For example, in some embodiments, a compressive modulus of at least about 0.1 Mpa is desired, although compressive strengths in the range of about 1 Mpa to about 20 Mpa are also desired. Often the compressive modulus is at least about 5 Mpa.
In some embodiments, implant 30 may also deliver desired pharmacological agents. The pharmacological agent may be a growth factor that may repair damaged tissue or bone and may include an osteoinductive factor, transforming growth factors, a platelet-derived growth factor, or other similar growth factors or combinations thereof having the ability to repair tissue or bone.
In other forms, implant 30 may comprise a pharmacological agent used for treating various spinal conditions, including degenerative disc disease, spinal arthritis, spinal infection, spinal tumor, and osteoporosis. Such agents include antibiotics, analgesics, anti-inflammatory drugs, including steroids, and combinations thereof.
The pharmacological agents, if any, can be dispersed within implant 30 for in vivo release. The pharmacological agents may be dispersed in implant 30 by adding the agents to implant 30 when it is formed, by soaking a formed implant 30 in an appropriate solution containing the agent, or by other appropriate methods. In other forms, the pharmacological agents may be chemically or otherwise associated with implant 30. For example, the agents may be chemically attached to an outer surface of implant 30.
In some embodiments, implant 30 may include an x-ray marker, such as a tantalum marker, to assist in positioning the implant. In other embodiments, a combination of larger x-ray markers and smaller x-ray markers may be used to facilitate observing the orientation of implant 30 when it is implanted into a medical patient. The x-ray markers can be more readily observed on x-rays, making the positioning and orientation of implant 30 more easily observed and corrected. To use implant 30, legs 34, 36, 38, and 40 are manipulated to form an “X”-shaped configuration with body portion 32 as shown in
Also shown in
In other embodiments, implant 30 can have indents and/or other surface features to facilitate collapsing and implanting implant 30 or to avoid cracking or tearing implant 30 when legs 34, 36, 38, and 40 are folded and unfolded. Features such as ridges to facilitate gripping the interspinous processes may also be included on implant 30.
Referring generally to
Implant 50 may be formed from a wide variety of biocompatible materials that are substantially rigid. Examples of such materials include plastics, metal, and/or combinations thereof. The nature of materials selected to form implant 50 should be selected such that implant 50 has a sufficient load-bearing capacity. In preferred embodiments, a compressive modulus of at least about 0.1 Mpa is desired, although compressive strengths in the range of about 1 Mpa to about 20 Mpa are more preferred. In other embodiments, the compressive modulus is at least about 5 Mpa.
To use implant 50, implant 50 is inserted in ramp 64 of positioning instrument 60. Implant 50 is then moved or pushed along ramp 64 to distal portion 62. As illustrated by pair of arrows A in
To use positioning instrument 60, a surgeon forms an incision in the medical patient. Next, the surgeon inserts the distal portion 62 of ramp 64 through the incision in the medical patient and positions the distal portion 62 between a pair of adjacent interspinous processes. Next, the surgeon loads an implant, such as implant 30 or implant 50, in the implant entry 65. The surgeon then pushes down on pusher handle 66 while holding ramp secure handle 70 to steady the positioning instrument 60. Next, the surgeon continues to push pusher handle 66 down thereby moving pusher 72 into ramp 64 to engage the implant and move the implant along the ramp 64. As the first pair of legs of the implant exit the distal portion 62, a surgeon starts to remove distal portion 62 from between the interspinous processes. The first pair of legs of the implant are positioned longitudinally along one side of the interspinous processes. By removing distal portion 62 from the interspinous processes and pushing pusher handle 66 towards ramp 64, the remaining two legs of the implant exit from distal portion 62 and are positioned longitudinally along the other side of the interspinous processes. During this process, all four legs of the implant are positioned longitudinally along the adjacent pair of interspinous processes. The adjacent pair of vertebrae are now separated to a corrected position by the implant. The implant positioned between the interspinous processes can be further connected to other orthopedic devices.
Illustrated in
While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.