PERIPROSTHETIC HIP FRACTURE CABLING SYSTEM
20220338911 · 2022-10-27
Inventors
Cpc classification
A61B17/8861
HUMAN NECESSITIES
International classification
Abstract
An improved fracture cabling system has one or more spacers. Each spacer has a longitudinal length extending along a body of the spacer. The body has an upper portion with an aperture configured to receive a wire or cable and a lower portion having one or more pairs of feet spaced by a longitudinal gap or groove. Each of the one or more pairs of feet is located on a lateral side of the spacer body and configured to contact a bone with a fracture. The gap is configured to be positioned over the fracture with each foot positioned on a side of the bone spaced from the fracture. The longitudinal length of the one or more spacers is preferably curved or arcuate. Each body of the one or more spacers has a leading end and a trailing end.
Claims
1. An improved fracture cabling system comprises: one or more spacers, each spacer has a longitudinal length extending along a body of the spacer, the body having an upper portion with an aperture configured to receive a wire or cable and a lower portion having one or more pairs of feet spaced by a longitudinal gap or groove, each of the one or more pairs of feet being located on a lateral side of the spacer body and configured to contact a bone with a fracture, wherein the gap is configured to be positioned over the fracture with each foot positioned on a side of the bone spaced from the fracture.
2. The fracture cabling system of claim 1 wherein the longitudinal length of the one or more spacers is curved or arcuate.
3. The fracture cabling system of claim 1 wherein each body of the one or more spacers has a leading end and a trailing end.
4. The fracture cabling system of claim 3 wherein the improved fracture binding comprises a plurality of spacers, each spacer abutting an adjacent spacer at the leading end or trailing end.
5. The fracture cabling system of claim 4 wherein each spacer has a leading end and a trailing end spaced arcuately between 15 degrees to 180 degrees.
6. The fracture cabling system of claim 4 wherein each spacer has a leading end and a trailing end spaced arcuately from 90 degrees to 180 degrees.
7. The fracture cabling system of claim 6 wherein the one or more spacers have a pair of sides, each side having the pairs of feet configured to engage the bone at longitudinally spaced locations, wherein the feet at the leading or trailing ends are partially rounded in shape and wherein the pairs of feet located from the ends are rounded in shape.
8. The fracture cabling system of claim 7 wherein each of the feet has a width of 3.0 mm to 4.0 mm or greater.
9. The fracture cabling system of claim 1 further comprises: a cable, the cable being inserted through the aperture of each of the one or more spacers and when tightened, secures each spacer in contact with the bone securely to set the fracture.
10. An improved bone stabilizing cabling system comprises: one or more spacers, each spacer has a longitudinal length extending along a body of the spacer, the body having an upper portion with an aperture configured to receive a wire or cable and a lower portion having one or more pairs of feet spaced by a longitudinal gap or groove, each of the one or more pairs of feet being located on a lateral side of the spacer body and configured to contact a bone in near proximity to a femoral head of the bone, wherein the gap is configured to be positioned over the bone with each foot positioned on a side of the bone spaced from the femoral head to stabilize and reinforce the bone.
11. The improved bone stabilizing cabling system of claim 10 wherein the longitudinal length of the one or more spacers is curved or arcuate.
12. The improved bone stabilizing cabling system of claim 10 wherein each body of the one or more spacers has a leading end and a trailing end.
13. The improved bone stabilizing cabling system of claim 12 wherein the improved fracture binding comprises a plurality of spacers, each spacer abutting an adjacent spacer at the leading end or trailing end.
14. The improved bone stabilizing cabling system of claim 13 wherein each spacer has a leading end and a trailing end spaced arcuately between 15 degrees to 180 degrees.
15. The improved bone stabilizing cabling system of claim 13 wherein each spacer has a leading end and a trailing end spaced arcuately from 90 degrees to 180 degrees.
16. The improved bone stabilizing cabling system of claim 15 wherein the one or more spacers have a pair of sides, each side having the pairs of feet configured to engage the bone at longitudinally spaced locations, wherein the feet at the leading or trailing ends are partially rounded in shape and wherein the pairs of feet located from the ends are rounded in shape.
17. The fracture cabling system of claim 16 wherein each of the feet has a width of 3.0 mm to 4.0 mm or greater.
18. The improved bone stabilizing cabling system of claim 10 further comprises: a cable, the cable being inserted through the aperture of each of the one or more spacers and when tightened, secures each spacer in contact with the bone securely to reinforce the bone.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The patent or application file contains at least one drawing/photograph executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
[0018] The invention will be described by way of example and with reference to the accompanying drawings in which:
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DETAILED DESCRIPTION OF THE INVENTION
[0042] The present invention increases the contact area to bone such that the cable 40 is restricted from penetrating the bone 2 as the cable 40 is tensioned. This prevents additional fracturing of the bone 2. It also improves the mechanical strength of the fracture repair construct.
[0043] Stainless Steel, titanium, or any other non-corrosive material, whether permanent or resorbable can be used to make the spacer body 11.
[0044] The present invention improves the repair of periprosthetic hip fractures. Currently a cable tensioned around a PPHF penetrates the proximal femur resulting in secondary femur fractures and loss of fixation of the periprosthetic fracture repair construct. The present invention limits and prevents cortical penetration of a tensioned cable. Thereby the fracture is stabilized, which permits fracture union.
[0045] The strength of any bone is directly proportional to how much of a load it bears from day-to-day. This process is very similar to muscle size and strength. Working out, exercising and lifting weights will result in increased muscle mass and strength. The same principle applies to bone. Normally, human bone is very tough and feels hard to the touch. Osteoporosis, is one circumstance whereby bone loses its strength. Another situation where bone becomes weaker is when it contains a metal implant. The femur or thigh bone on the occasion of a hip replacement has a metal stem placed in the upper portion of it. When this hip stem sits in the upper femur for a period of time, the surrounding bone weakens. This weakening is due to stress shielding. The process of stress shielding simply means that the metal stem bears all of the load with standing and it shields the adjacent bone from the stresses or work of standing. This may at first sound like a favorable process, except the bone that is shielded from stress will weaken slowly over time. The end result is twofold. First, the hip stem may loosen. Secondly, a peri-prosthetic femur fracture (PPFF) will occur more easily in the upper part of the thigh bone. Repair of a PPFF is challenged by the presence of the hip stem. The hip stem limits passage of screws across the width of the broken bone because the hip stem is in femoral canal. The best option at this point to fix a PPFF is to use cables. Except, the bone is weak and any cable tightened around the bone will simply cut into the bone and lose the ability to hold a fracture in place until it heals. A simplistic analogy would be to imagine a warm knife cutting through butter. The cables that are currently available for PPFF repairs are commonly only 1.7 mm in width or diameter, typically between 1.6 mm and 2.0 mm in width or diameter. This narrow width or diameter is part of the problem and why cables around a PPFF do not provide any fixation. The solution this invention offers is to pass a spacer 11 with feet 20 that are wider than the cable 40 over the cable 40, preferably by passing the cable 40 through an aperture in the spacer 11. The feet 20 are twice the width or diameter of a cable 40. The spacer 11 has two feet fore or leading and two feet after or trailing. Every foot 20 has a diameter or width twice the width of a cable 40. Accordingly, for a cable diameter of 1.5 mm to 2.0 mm, each foot will have a width of 3.0 mm to 4.0 mm or greater. Therefore, the two fore or leading feet offer four times the surface area of a cable 40. Likewise, the two after or trailing feet 20 offer four times the surface area of a cable 40. This increased surface area of the feet 20 on the cable spacer 11 improves the fixation of a cable 40 tensioned around a stress shielded bone 2 because the cable 40 cannot cut into the weakened bone 2. A simplistic analogy would be to imagine trying to pass a spoon through butter.
[0046] These features are explained in reference to the detailed drawings. In some embodiments, the spacer 11 is a single piece structure with an arcuate or curved shape to fit about an exterior surface of the bone 2. This single piece structure typically extends about 90 degrees to 180 degrees, but can extend from 15 degrees to 180 degrees, preferably 30 degrees or 45 degrees to 180 degrees. In other embodiments, the spacer 11 has a short circumferential arc of say 30 degrees to 60 degrees or 15 degrees to 90 degrees and can be stacked in a plurality of such spacers 11 around a cable 40 to create a variety of circumferential or arcuate lengths extending around the bone 2 to completely encircle the bone 2 up to 360 degrees if so desired. Normally this encirclement can be less than that to achieve the desired protection of the bone 2.
[0047] With reference to
[0048] With reference to
[0049] With reference to
[0050] Importantly, with reference to
[0051] With reference to
[0052] With reference to
[0053] With reference to
[0054] With reference to
[0055] In a second embodiment shown in
[0056] With reference to
[0057] With reference to
[0058] As illustrated in
[0059] With reference to
[0060] When the cable 40 is passed through the opening 30, the cable 40 can be crimped together by a crimping device 50 that allows one end of the cable 42 to be positioned in the crimping device 50 and the other end 41 to be inserted through another opening in the cable crimping device 50. Therefore, when tensioned and crimped, the embodiments will be held in positioned tightly against the bone 2.
[0061] In
[0062] With reference to
[0063] Alternatively, in the prior art, flat devices are commonly employed. However, these flat devices are limited in that they provide a flat surface around which the bone 2 is to be accommodated whereas the feet provide an arcuate shape that better contacts the bone 2 locally and provides a superior contact point that is stabilized due to the fact that the aperture 30 for receiving the cable 40 has a slot 32 that centralizes the cable 40 in such a fashion that it cannot shift. This allows the radially inner portion of the spacer 11 to be stabilized by effective use of pairs of feet 20 on each lateral side of the device 10.
[0064] With reference to
[0065] As further illustrated in
[0066] With reference to
[0067] The photographs of
[0068] Fractures of the femur after a total knee or a total hip replacement procedure are common. These fractures are called periprosthetic fractures (PPF). They are increasing in frequency due to the steady increase in adult joint reconstruction procedures performed annually. There are two significant challenges in repairing a PPF. First, the joint replacement implants interfere with application of fracture repair implants, such as plates and screws. As a result, metal cables are used. Normally, in non-osteoporotic bone cables provide adequate circumferential placement around a femur without cable penetration as shown in the photograph of
[0069] The inventor of the present invention has directly observed cables penetrating femurs applied in PPFF repairs. He studied this phenomenon further by obtaining 24 cadaver femurs that had a hip arthroplasty stem in place for a minimum of 6 months. In every cadaveric femur specimen, the cable penetrated the femoral bone when tensioned to the cable manufacturer's recommended tension level as shown in
[0070] It is believed that the improved device 10 will distribute the loads against the bone 2 in such a fashion that bone repair of a fracture or stabilization of a weakened bone as in a hip replacement can be achieved without inducing any further fractures to the bone 2. This greatly enhances the procedure and makes it more likely for a favorable outcome for those who receive hip or knee replacements. These and other attributes of the present invention are as claimed in the claims as presented hereinafter.
[0071] The radius of curvature in conjunction with the fore and aft feet provide limited contact of a cable around a femoral bone. This is similar to the previously published spacer
[0072] The improved fore and aft feet design prevents cable penetration or cortical fracture in stress shielded femurs. This is a new feature and different than the published spacer. Ironically, the published spacer is all about limited contact, whereas this new spacer adds contact area slightly to distribute tensioning forces to prevent cable penetration and cortical fracture in stress shielded femurs.
[0073] Periprosthetic femur fractures (PPFF) near hip or knee replacements are common. PPFF have osteoporotic bone from stress shielding which limits the use of cables for fixation of a PPFF. Stress shielding is a bone remodeling process. Femoral bone stress shielding occurs within 6 months of a joint reconstruction procedure. When a metal implant is placed in the femur for a joint reconstruction procedure, it shields the adjacent bone from weight bearing loads. This is stress shielding. In response to decreased loads to bone adjacent to a total joint implant, the bone becomes less dense or osteoporotic. This can lead to fractures. The fractures are difficult to treat because the bone is weaker and less able to hold metal fracture repair implants such as plates, screws, or cables. We have observed that metal cables 40 penetrate the femur bone, and fracture stress shielded PPFF as shown in
[0074] Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described, which will be within the full intended scope of the invention as defined by the following appended claims. The surgical access window described herein encompasses the dimensions presented and any and all variations applicable to the methods and surgical technique described directly or indirectly intended with this device.