Bone screws and wires have been in clinical use for decades for bone fixation. These important bone fixation devices have evolved from rigid stainless steel or titanium wires and screws to shape changing nitinol implants that through their expansion are fixated in bone. These implants are commonly placed along the centerline of bone and thus reside within the bone's intra-medullary canal.
The early rigid bone fixation devices were commonly threaded or drilled into bone where the more modern devices are implanted in drilled holes and expand through mechanical means to lock into bone but none, other than the invention described herein, lock into bone and then shorten to pull together and compress the bony segments. Intra-medullary bone fixation technology includes: (1) wires, (2) screws, (3) multi-component screws, (4) heat sensitive shape memory alloy implants cut from plates, and (5) polymer pins intended to degrade over time.
The implant embodiments of the present invention have advantages over the prior art because they store mechanical energy and impart that energy to bone through shape change and predictable bone-to-bone compression. The implant embodiments of the present invention pull together and compress bone to promote healing. The implant embodiments of the present invention are hollow, which allow bone to grow within the implants so as to further lock the implant into bone and conduct new bone through the implants' lumen to bridge bones intended to heal together.
Some prior art implants may change shape or be caused to change shape but do not lock into the separate bone segments and then act to pull together and compress bone.
Instruments, to place the implants into bone, complements the implants' method of action by holding the implants extended and at their minimum diameter, allowing the implants to be manipulated in bone, releasing the implants when fully inserted, and protecting the implants during handling and shipment.
As will be clear in the following detailed description of the prior art, the embodiments disclosed and taught in the present Application overcome the prior art deficiencies in ease of use, manufacturing, mode of operation, strength, cost and allows hospital procedures that limit disease transmission.
Expanding and Bone Locking Implants
The embodiments of the present invention overcome the deficiencies of other within bone fixation implants such as (1) requiring heating or cooling, (2) having a temperature dependent fixation force, (3) requiring ancillary equipment to manipulate the implant, (4) being implanted in the soft martensitic phase of nitinol, (5) requiring an expensive multiple step manufacturing process to set both the staple shape and transition temperatures, and (6) others that become more clear in the review of the embodiments of the present invention.
The embodiments of the present invention overcome the deficiencies of the prior elastic staples and intramedullary bone shape changing bone fixation devices such as (1) providing the surgeon limited time to place it in bone, (2) designs that cannot contract their length, (3) requiring expensive ancillary equipment to manipulate the implant, (4) cooling of the implant prior to opening for placement, (5) designs that can not simultaneously expand to lock into bone and contract to pull together and compress bone, and (6) others deficiencies that will become more clear in the review of the embodiments of the present invention.
Instrument and Implant Devices and Methods
The foregoing discussion illustrates the deficiencies of the prior art and the lack of a simple shape changing bone fixation implant, instrument for its implantation and method of use consistent with the demands of surgery. Product packaging may be in reusable hospital sterilization tray and a manufactured sterile kit containing the implant and instruments required for surgery. In the discussion of the embodiments of the subject invention its benefits will be realized as a simple, reliable, low cost solution to present an elastic energy storing shape changing staple to bone and releasing the staple so that it can pull together and compress bone even in the presence of gaps that can form during bone healing.