The present invention relates to external fixators, intramedullary pins, and nails, and an improved method of fixation.
It is well known that fractured bones may be effectively healed by fixing the fractured bone in a secure position to prevent slippage or separation. With a bone so secured, bone tissue will grow and bone cells will multiply in the region of the fracture.
One common technique for securing fractures is an external fixation pin or screw that extends into or through the bone fragments to secure the fragments in a fixed position. Typically, the fixation pin pierces the outer cortex of the fractured bone, crosses the medullary canal and embeds in or passes through the opposite cortex.
Another technique is the use of intramedullary pins (also known an IM pin) or intramedullary nail (also known as an IM nail, or inter-locking nail, or Küntscher nail), that are driven through the bone and across the fracture. Intramedullary pins tend to be round where as nails tend to have a series of holes through the proximal and distal portion of the nail through which a series of pins are driven through the bone and through the nail to further strengthen the construct.
Like plates and screws, external fixators, intramedullary pins, or nails provide strong support for broken bones. External fixators, intramedullary pins, or nails provide the advantage of minimal tissue disruption which allows for rapid healing. Unlike plates or pins, part of the external fixator sits outside the body; pins run from the bone to outside the skin where they connect to a weight bearing rod.
External fixation involves placing either threaded or unthreaded pins percutaneously through the skin and overlying tissues and through a bone. The external fixator pin is driven through or screwed into the bone and may or may not exit the skin on the other side opposite the insertion side. Once the fixator pins are set in the bone and the fracture is aligned as desired, the pins are held in place or fixed by a rod, modular device, tubular device, or the like, that is clamped to the pins external to the limb. Recently, the rod and clamp configuration has been replaced in some instances by a polymer that secures the pins external to the limb. The polymer is typically an epoxy or similar product. The apparatus holds the bones in position until healed at which time the entire apparatus is removed.
Typically, a hole is drilled through the bone and the external fixator pin, intramedullary pin, or nail is then placed through this hole. Failure to do so may result in cracking of the bone at the pin site. This is one cause of early pin failure and loosening may result or the bone fragment may shift resulting in a more complicated fracture. Because of this, the surgeon usually drills an initial hole through the bone and overlying tissues. The surgeon then must pull the drill back out, set the drill down and pick up the external fixator pin and then search for the hole that was drilled in order to place the pin through the bone. This can be time consuming and complicated since the overlying tissues are mobile and often obscure the drill hole. The surgeon may be unable to locate the drill hole to place the pin. This may necessitate the redrilling of the hole further weakening the bone and potentially leading to fracture.
Some fixator pins are self-drilling and self-tapping. These pins have smooth, cylindrical shafts with the points matched into a pointed spade configuration which formed the drill tip, knife edges that scraped away the bone when the shaft was turned, and a self-tapping thread. The self-tapping thread continued up the shaft for a distance sufficient to pass through the bone for which the pin was designed.
Self-drilling, self-tapping screws, pins, and nails have several disadvantages. First, the knife edge of the drill point is not very sharp. Consequently, the drill advances at a relatively slow speed through the bone. This slow speed was generally slower than the speed with which the self-tapping thread would advance if the hole were pre-drilled before attempting to tap the pin into the bone. This speed differential caused the thread portion to strip out the threads just cut in the bone because of the inability to advance as fast as the self-tapping thread would normally advance. A second disadvantage is that the relatively slow speed of drill bore progression achieved by this structure resulted in higher temperatures from friction heating of the bone surrounding the hole.
Another self-tapping, self-drilling orthopedic fixation screw includes a cannula through the shaft of the screw. The cannula is placed over a guide pin mounted in a guide hole in a bone to drill and tap a hole at predetermined location in the bone. In this manner the fixation pin is attached to the bone.
It is an object of this invention to provide an external fixator pin, intramedullary pin, or intramedullary nail with a removable or non-removable drill portion. The drill portion is removed when no longer necessary leaving the threaded and engaged portion of the external fixator, intramedullary pin, or nail placed within the bone. The removable drill portion would also be applicable to smooth, non-threaded variants of fixator pins allowing quick and easy removal of the sharpened drill bit portion of the fixator. The external fixator pin is useable in all applications including but not limited to unilateral uniplanar applications, uniplanar bilateral applications, bilateral biplanar applications, unilateral biplanar applications, and the like. Both planar and circular external fixators can be used with the disclosed external fixator pins. Similarly, the intramedullary pin or nail may be placed in any direction with respect to the bone.
As used herein, the term fixator pin is used to include an external fixator pin, an intramedullary pin, an intramedullary nail, Schanz screw, inter-locking nail, Küntscher nail, half pins, centrally threaded full pins, Steinmann pins, smooth transfixation pins, positive or negative profile transfixation pins, and the like.
The disclosed external fixator pin allows better purchase and positive thread engagement into the bone. Better purchase is important since the bone is only solid on the outer portion with soft bone or marrow internally. Thus, threads only have purchase on the outer two sides of the bone, referred to as the outer cortices of the bone. The disclosed external fixator pin substantially eliminates the risk of the external fixator threads stripping out of the bone if the drill bit did not move through the second cortex of bone at the same rate as the threaded portion of the fixator.
Combining the drill bit onto the external fixator pin, intramedullary pin, or nail in a removable configuration allows the surgeon to drill the guide hole and set the pin without removing it from the drilled hole, which simplifies the placement of the fixator pin, intramedullary pin, or nail, saving time and reducing complications. The drill bit is a fluted drill bit, a twist drill bit, a brad point bit, a high speed steel bit, a titanium nitride coated bit, a cobalt high speed steel bit, an auger, a spade, or the like.
As discussed above, another problem encountered with prior art pins is that once a hole is drilled through both cortices of the bone and a pin, screw or nail is inserted, the pin, screw or nail may not enter the hole on the far side of the bone. If the external fixator pin, IM pin or IM nail misses the far cortex hole, it often results in cracking of the bone near the drilled hole or a stripping of the threads in the near hole. This problem is eliminated when the drill is combined with the pin or nail.
According to one aspect of the invention, a snap-off or separation point is incorporated between the external fixator pin, intramedullary pin, or nail portion and the drill bit portion that allows simple removal of the drill bit when no longer necessary.
According to one aspect of the invention, a right-handed thread, or a thread that is the same as the drill direction and the fixator pin thread, is incorporated between the external fixator pin portion and the drill bit portion that allows simple removal of the drill bit when no longer necessary.
According to one aspect of the invention, a left-handed thread, or a thread that is opposite the drill direction and the fixator pin thread, is incorporated between the external fixator pin portion and the drill bit portion that allows simple removal of the drill bit when no longer necessary.
According to one aspect of the invention, the external fixator pin is unthreaded, has a positive profile, or a negative profile.
According to one aspect of the invention, a snap-off drill bit comprising a fluted drill bit of various drill designs is joined to the external fixator pin via a frangible connection comprising at least one feature formed through the outer surface of the shaft at a point either near the threaded or non-threaded portion of the external fixator pin in the case of a pin that does not pass through the patient's tissues on the far side of the limb or a suitable distance away from the threaded or non-threaded portion of the external fixator pin for pins that are placed completely through both sides of the limb.
According to one aspect of the invention, a cut-off drill bit comprising a fluted drill bit of various drill designs and lengths is joined to the external fixator pin near the threaded or non-threaded portion of the external fixator pin and removed by a cut-off tool.
According to one aspect of the invention, a machine threaded drill bit comprising a fluted drill bit of various drill designs and lengths is joined to the external fixator pin near the threaded or non-threaded portion of the external fixator pin via internal or external threads or features and removed by unthreading or unscrewing from the external fixator pin.
According to one aspect of the invention, the drill bit, which is removable via a frangible connection, brittle snap off section, threaded features, cut-off tools or processes, and the like, is joined to a threaded fixator pin, a non-threaded fixator pin, an intramedullary pin, an intramedullary rod, or the like.
According to one aspect of the invention, the external fixator pin or nail includes multiple frangible points on either or both the far side of pin or near side of pin to break off at set distance from threads (a set distance away from the threads nearer the surgeon). This would avoid having to cut and grind pin on near side of fracture and give surgeon options for where to break off the pin. This may be useful with external fixator pin or IM pins that can be broken off at a set distance from the pins.
One advantage of this drill/pin configuration is that the drill bit is only used once and then broken or cut off and discarded. This ensures that the drill bit is always sharp easing the creation of the drill hole. Reusable drill bits, which are commonly used in surgery, become dulled with repeated use and so lead to increased friction and heating of the bone. This results in bone death adjacent to the drill hole. This bone is quickly resorbed by the body leading to premature loosening of the pin, increased infection rates, and poor or delayed healing. The use of one-time use drill bits in this embodiment reduces these problems.
In the drawings:
External skeletal fixation is used for primary or secondary stabilization of open or closed long bone fractures, spinal fractures and luxations, luxations or arthrodesis of certain joints, and to provide support following ligament or tendon reconstruction. External skeletal fixation can also be used to dynamically enhance long bone growth following premature physeal closure, and to facilitate and reestablish limb alignment in juvenile patients and select adult patients. External skeletal fixators use percutaneous transfixation implants that may be stainless steel wires (Kirschner wires), pins, or both, coupled with an external frame that may be linear (connecting bars), circular (transfixation pins connected to rings, which are connected by threaded bars), or a hybrid, which is a combination of linear and circular external skeletal fixation elements, and may be placed into various geometric configurations.
External skeletal fixator frames can be composed of a variety of materials such as stainless steel, carbon fiber, titanium, polymers, or acrylics. The final frame design may function as a supportive exoskeleton for fractures and osteotomies, or as rigid immobilization for transarticular applications. External skeletal fixation is especially effective with highly complex fractures. While widely used in humans, external skeletal fixators are well tolerated by animals including dogs and cats, allowing early return to limb function following fracture fixation, and usually can be removed without the need for administration of general anesthesia to the patient. Finally, external skeletal fixation systems are generally more economical for the surgeon and the client. Following cleaning and sterilization, some components can be reused on multiple patients over time.
The external fixator pin 10 shown in
As shown in
The external fixator pins 10 and 12, shown in
The external fixator pin 112 is installed using the following procedure. After an incision is made in the skin, a sleeve is inserted through the incision and pushed onto the bone. The sleeve is held steady and a trocar is tapped on the bone surface to create an initial impression. The impression prevents slipping of the drill bit during drilling. The trocar is removed and a long drill bit is inserted through the sleeve and both cortices are drilled through. The drill bit is withdrawn and the external fixator pin is introduce through the sleeve threaded into bone so that the thread 126 is securely engaged into the far cortex. The external fixator pin 112 is then attached to a connecting bar 30 via a clamp 20. Alternatively, the external fixator pin 112 is installed without a sleeve or trocar in a two-step process. In the two-step process a hole is drilled with a drill bit. Once the hole through the bone is drilled, the drill bit is removed and the external fixator pin is installed in the hole that was drilled in the bone. This external fixator pin 112 suffers from the limitations discussed above.
The external fixator pin 12 shown in
According to one aspect of the invention shown in
The external fixator pin 80 shown in
According to one embodiment of the invention, the screws or bolts 96 have a removable drill tip and a separable connection. In this manner, the hole for the bolt 96 can be drilled and the drill tip can be removed in a manner similar to the fixator devices discussed above.
While this invention has been described by reference to a preferred embodiment, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Multiple variations and modifications are possible in the embodiments of the invention described here. Although certain illustrative embodiments of the invention have been shown and described here, a wide range of modifications, changes, and substitutions is contemplated in the foregoing disclosure. In some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is intended that the invention not be limited to the disclosed embodiment, but that it have the full scope permitted by the language of the following claims.
Filing Document | Filing Date | Country | Kind |
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PCT/US2019/017677 | 2/12/2019 | WO | 00 |
Number | Date | Country | |
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62637783 | Mar 2018 | US |