Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2002-03-25
2004-10-26
Reip, David O. (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
Reexamination Certificate
active
06808527
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to intramedullary nails used for treatment of a fracture of a bone having a medullary canal extending longitudinally within the bone and, more particularly, to the structure of the intramedullary nail and/or spacer and methods for anchoring the intramedullary nail and spacers with respect to one or more fragments of the fractured bone.
BACKGROUND OF THE INVENTION
Intramedullary nails are used by orthopaedic surgeons to treat fractures involving long bones such as the femur, humerus, tibia, fibula, and others. In such treatment, the medullary canal of the various fragments or pieces of the fractured bone is drilled out, reamed, or otherwise opened from one end. The intramedullary nail is then longitudinally placed in the medullary canal to contact at least two of the fragments, i.e. such that the nail extends on both sides of the fracture. As used herein, the term “fragment” refers to a portion of a fractured bone regardless of whether the fracture is complete. When implanted, the intramedullary nail supports and strengthens fragments of the fractured bone during healing of the fracture.
Various types of intramedullary nails are well known within the medical device arts, and several different methods have been used to attach the intramedullary nail to and within the bone. As an example, in U.S. Pat. No. 4,338,926 to Kummer et al., an intramedullary nail is shown that provides a compressive force radially outward on an interior wall of the cortex structure surrounding the intramedullary nail. The compressive force secures the Kummer intramedullary nail within the medullary canal of the fragments. Similarly, in U.S. Pat. No. 5,514,137 to Coutts, cement is injected through a cannula in an intramedullary nail to the bone. Other intramedullary nails employ a more secure and mechanically positive attachment to the bone, such as through the use of one or more bone fasteners that extend generally transversely to the longitudinal axis of the intramedullary nail and through the cortex of the bone. The bone fasteners is received within a receiving recess or through-hole within the intramedullary nail to secure the intramedullary nail relative to the bone fastener. In a transverse attachment, the receiving opening of the intramedullary nail defines an axis that is at an angle to the longitudinal axis of the nail (commonly at 45° and 90° angles), and the bone fastener is advance on this receiving opening axis. U.S. Pat. No. 4,733,654 to Marino, U.S. Pat. No. 5,057,110 to Kranz et al., U.S. Pat. No. 5,127,913 to Thomas, Jr., U.S. Pat. No. 5,514,137 to Coutts (proximal end) and others disclose such a transverse bone fastener attachment in a bicortical attachment. U.S. Pat. No. 5,484,438 to Pennig shows a nail design with a recess that permits only unicortical attachment. The subject invention particularly pertains to intramedullary nails that utilize bone fasteners transversely through the cortex for attachment.
Problems may arise when attaching an intramedullary nail to a fragment with a bone fastener. It is occasionally difficult for the surgeon to properly align the bone fastener and/or a hole for the bone fastener with the receiving opening in the intramedullary nail. Part of the alignment problems is simply due to difficulty in aligning the bone fastener with the receiving opening when the receiving opening is within the bone. Additionally, the intramedullary nail may be slightly bent or distorted during insertion thereof into the medullary canal. Such bending and/or distortion may be desired in some instances so that the shape of the inserted intramedullary nail better matches the particular shape of the medullary canal for a particular patient.
Regardless of whether intended or unintended, such bending or distortion of the intramedullary nail creates further alignment errors between the bone fastener and/or a hole for the bone fastener and the receiving opening on the nail. Four types of alignment errors can be identified: (a) in transverse displacement (e.g., when the axis of the bone fastener is in the same transverse plane as the receiving opening in the intramedullary nail but does not intersect the axis of the intramedullary nail); (b) in longitudinal displacement (i.e., when the bone fastener is at a different longitudinal location than the receiving opening in the intramedullary nail); (c) in longitudinal angular misalignment (i.e., when the axis of the receiving opening and the axis of the bone fastener are at different angles relative to the longitudinal axis of the intramedullary nail); and (d) in transverse angular misalignment (i.e., when the axis of the receiving opening and the axis of the bone fastener are in the same transverse plane but at different radial positions relative to the intramedullary nail.
In view of the above, various types of jigs have been proposed to reduce alignment errors, such as shown in U.S. Pat. No. 4,733,654 to Marino and U.S. Pat. No. 5,776,194 to Mikol et al. Such jigs may be temporarily attached to the proximal end of the intramedullary nail to help align the bone fastener and/or the drill to the receiving opening in the intramedullary nail. While such jigs are helpful, the jigs become less reliable as distance from the proximal end of the intramedullary nail increases, particularly if any bending of the intramedullary nail has occurred. Additional solutions are needed, especially for attaching the distal end of the intramedullary nail to a distal fragment.
Another method to reduce such alignment problems is to locate the receiving opening(s) in-situ, such as through an x-ray or the use of magnets as taught in U.S. Pat. No. 5,127,913 to Thomas, Jr. Such methods are not typically preferred by surgeons in as much as the methods require significant additional time and effort during the orthopaedic surgery, to the detriment of the patient.
A third method to reduce such alignment problems is to drill the receiving opening into the intramedullary nail only after the intramedullary nail is placed into the bone, allowing the receiving opening to be formed at a range of locations. Such in-situ drilling is disclosed in U.S. Pat. No. 5,057,110 to Krans et al., wherein a tip section of the intramedullary nail is formed of a bioresorbable material. Bioresorbable materials, however, are not as strong as metals, leading to an intramedullary nail that is weaker than desired and has a weaker attachment than desired.
Further problems with intramedullary nails occur during placement of the intramedullary nail. For minimal damage to cortical tissue of the bone and most beneficial to healing, both the hole that is drilled in the medullary canal for the intramedullary nail and then the intramedullary nail itself, need to be precisely located and secured with respect to the medullary canal.
Additional problems with intramedullary nails occur due to the healing requirements of a bone with respect to the strength and rigidity of the intramedullary nail. U.S. Pat. No. 4,756,307 to Crowninshield and U.S. Pat. No. 4,338,926 to Kummer et al. disclose intramedullary nails with bioresorbable portions to weaken the mail relative to the bone over time. These intramedullary nails, however, forsake the use of a transverse bone fastener to achieve the benefit of the bioresorbable portions.
It would thus be advantageous to provide an intramedullary nail that overcomes the above-noted shortcomings. It would be further advantageous to provide an intramedullary nail and related portions and/or components that overcome the above-noted and other shortcomings.
SUMMARY OF THE INVENTION
The subject invention is an intramedullary nail for treatment of a fracture of a bone by placement of the intramedullary nail within the medullary canal of the fractured bone. The intramedullary nail is formed with at least one opening in an exterior side that is adapted to receive a spacer or window insert of a non-metal material. The opening and window insert have cooperating structures that provide a spring type elastic fit, sna
Lower Jerry L.
Overaker David W.
Baxter Jessica R.
DePuy Orthopaedics, Inc.
Maginot Moore & Beck
Reip David O.
LandOfFree
Intramedullary nail with snap-in window insert does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Intramedullary nail with snap-in window insert, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Intramedullary nail with snap-in window insert will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3286675