Systems and methods for using polyaxial plates
Certain embodiments of the invention provide plates for treating periarticular fractures or other non-full body weight bearing applications that combine polyaxial fixation with a low profile and enhanced contouring that more closely conforms to bone. Such plates can be designed to achieve buttressing effect and/or to be used in a reinforcement mode. Other features can be combined with these. Such plates can be created for use on bone sites such as on a tibia, fibula, metatarsal, calcaneous, other foot bone, humerus, radius, ulna, spinal, maxillofacial, as well as sites on other bones.
1. A bone fixation assembly for treating a fracture of a bone site, the assembly comprising:
a bone plate having an interior surface configured to contact bone and an exterior surface, the bone plate comprising:
a head portion configured to conform to a metaphysis of the bone, the head portion having one or more polyaxial openings, and
a shaft portion that extends from the head portion and that is generally elongated and configured to conform to a diaphysis of the bone, the shaft portion defining a first slot and having one or more polyaxial openings, the first slot having parallel side walls;
wherein the one or more polyaxial openings each comprises an inner surface having a plurality of fins protruding from the inner surface.
2. The assembly of claim 1 , wherein the head portion is approximately delta-shaped.
3. The assembly of claim 1 , wherein the first slot is elongated along a length of the shaft.
4. The assembly of claim 1 , wherein the head portion includes three or more polyaxial openings arranged along a direction substantially transverse to a length of the shaft.
5. The assembly of claim 1 , further comprising one or more fasteners for engaging the one or more polyaxial openings, wherein the plurality of fins are deflectable relative to a head of the one or more fasteners when the one or more fasteners is inserted into the one or more polyaxial openings such that the one or more fasteners may be inserted and retained at any one of a plurality of angles relative to the one or more polyaxial openings.
6. The assembly of claim 5 , wherein the plurality of fins comprise a concave upper surface portion.
7. The assembly of claim 1 , wherein the exterior surface is convex.
8. The assembly of claim 1 , wherein the interior surface is concave.
9. The assembly of claim 1 , wherein the interior surface comprises one or more undercuts that traverse across the interior surface.
10. The assembly of claim 1 , wherein the bone plate further comprises an edge comprising at least one scallop.
11. The assembly of claim 1 , wherein the first slot is at least partially threaded, is non-threaded, or comprises an inner surface and a plurality of fins protruding from at least a portion of the inner surface.
12. The assembly of claim 1 , wherein the first slot is configured to accept cortex, compression, osteopenic, or locking screws.
13. The assembly of claim 1 , wherein the bone plate comprises a thickness of approximately 2 mm or less.
14. The assembly of claim 1 , wherein the head portion defines a second slot, the second slot having parallel side walls.
15. The assembly of claim 14 , wherein the second slot is elongated along a direction substantially perpendicular to a length of the shaft.
16. The assembly of claim 4 , wherein a central axis of at least one of the three or more polyaxial openings in the head portion is oriented orthogonally relative to the interior or the exterior surface of the bone plate, and wherein a central axis of at least another one of the three or more polyaxial openings in the head portion is oriented non-orthogonally relative to the interior or the exterior surface of the bone plate.
17. The assembly of claim 1 , wherein an axis of at least one of the one or more polyaxial openings in the shaft portion is oriented non-orthogonally relative to the interior surface of the bone plate.
18. The assembly of claim 1 , wherein the plurality of fins protruding from the inner surface of each of the one or more polyaxial openings have bases that intersect the inner surface, the intersection between the bases and the inner surface defining a single plane.
19. A low profile bone plate having an interior surface configured to contact bone and having an exterior surface, the bone plate comprising:
a head portion that is approximately delta-shaped, the head portion defining a plurality of polyaxial openings; and
a shaft portion that extends from the head portion and that is generally elongated, the shaft portion defining a plurality of polyaxial openings along a length of the shaft and defining a first slot, the first slot having parallel side walls,
wherein the one or more polyaxial openings each comprises an inner surface having a plurality of fins protruding from the inner surface and deflectable relative to a head of a fastener such that the fastener may be inserted and retained at any one of a plurality of angles relative to the one or more polyaxial openings, at least one of the one or more polyaxial openings comprising a concave upper surface portion.
20. The low profile bone plate of claim 19 , wherein each of the one or more polyaxial openings includes five fins.
21. The low profile bone plate of claim 19 , wherein at least one of the head portion or the shaft portion defines one or more provisional pin openings.
22. The low profile bone plate of claim 19 , wherein the plurality of fins protruding from the inner surface of each of the one or more polyaxial openings have bases that intersect the inner surface, the intersection between the bases and the inner surface defining a single plane.
23. The low profile bone plate of claim 19 , wherein the head portion includes three or more polyaxial openings arranged along a direction substantially transverse to the length of the shaft.
24. The low profile bone plate of claim 23 , wherein a central axis of at least one of the three or more polyaxial openings in the head portion is oriented orthogonally relative to the interior or the exterior surface of the bone plate, and wherein a central axis of at least another one of the three or more polyaxial openings in the head portion is oriented non-orthogonally relative to the interior or the exterior surface of the bone plate.