BIASING DEVICE FOR SPINAL DEVICE

Abstract

A spinal device includes a rod which has a first end disposed in a housing and a second end which protrudes out of the housing through an aperture and which is movable to protrude more out of the housing or less out of the housing. A biasing device, mounted on the rod, includes a series of connected at-least partial coils. A first end of the biasing device is arranged to abut against the housing and a second end of the biasing device, opposite to the first end, is affixed to the rod.

Claims

1. A spinal device, comprising: an implantable elongated member; and an implantable biasing device coupled to said implantable elongated member, said implantable biasing device including a series of connected partial coils extending partially and not completely around said implantable elongated member.

2. The spinal device according to claim 1, wherein said series of connected partial coils subtends an angle of less than 360°.

3. The spinal device according to claim 2, wherein said series of connected partial coils includes pairs of connected neighboring coils, and wherein said pairs of connected neighboring coils are circumferentially separated from one another by a circumferential gap.

4. The spinal device according to claim 3, comprising: a polyaxial-joint attachment member, wherein said implantable elongated member extends from said polyaxial-joint attachment member.

5. The spinal device according to claim 4, comprising: a fastener affixing said implantable biasing device to said implantable elongated member, wherein said implantable biasing device includes an end portion, and said fastener affixes said end portion of said implantable biasing device to said implantable elongated member.

6. The spinal device according to claim 5, wherein said fastener is a set screw.

7. The spinal device according to claim 3, comprising: a fastener affixing said implantable biasing device to said implantable elongated member, wherein said implantable biasing device includes an end portion, and said fastener affixes said end portion of said implantable biasing device to said implantable elongated member.

8. The spinal device according to claim 7, wherein said fastener is a set screw.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0014] The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

[0015] FIG. 1 is a simplified pictorial illustration of a spinal device, constructed and operative in accordance with an embodiment of the invention;

[0016] FIG. 2 is a simplified enlarged illustration of a biasing device of the spinal device of FIG. 1;

[0017] FIG. 3 is another simplified illustration of the biasing device, showing circumferential gaps between ends of partial coils of the biasing device; and

[0018] FIG. 4 is a simplified sectional illustration of the spinal device.

DETAILED DESCRIPTION OF EMBODIMENTS

[0019] Reference is now made to FIGS. 1-3, which illustrate a spinal device 10, constructed and operative in accordance with a non-limiting embodiment of the invention.

[0020] Spinal device 10 includes a rod 12 which has a first end 14 (FIG. 4) disposed in a housing 16 and a second end 18 which protrudes out of housing 16 through an aperture 19 and which is movable to protrude more out of housing 16 or less out of housing 16. The term “rod” throughout encompasses any element with a round or non-round, regular or irregular perimeter, such as but not limited to, a rod, bar, lug, wire, post and others.

[0021] As seen in FIG. 4, rod 12 may be coupled with a ratchet mechanism 20 for controlling the amount rod 12 protrudes out of housing 16. Ratchet mechanism 20 may include ratchet teeth 22 formed along an axial portion of rod 12, and a pawl 24 arranged to catch on one of the teeth 22. Pawl 24 may extend from a controller element 26 mounted about a pivot 27 and provided with an eccentric cam 28. Rotation of eccentric cam 28 moves pawl 24 to one of three positions: a) in ratchet engagement with teeth 22 so that rod 12 can incrementally move in one direction, b) in locked engagement with teeth 22 so that rod 12 cannot move at all, and c) moved out of engagement with teeth 22 so that rod 12 can move in both directions freely. Other ratchet mechanisms can be used. Alternatively, no ratchet mechanism is used; for example, rod 12 may be urged by an internal spring inside housing 16.

[0022] Two polyaxial-joint attachment members 30 (such as but not limited to, a bearing race or simple hole) may be provided in device 10, one at the second end 18 of rod 12 and the other one at another portion 21 of housing 16. Both polyaxial-joint attachment members 30 are used to attach device 10 to available bone structure of the spine, such as by means of pedicle screws that pass through members 30. It is noted that even after tightening a fastener to member 30, the fastener securely holds the pedicle screw in place while enabling polyaxial rotation, as shown in U.S. patent Ser. No. 10/245,081.

[0023] Device 10 includes a biasing device 32, which may be an add-on accessory which can be added to device 10 prior to or after installation in a patient; alternatively device 10 can be provided by the manufacturer with biasing device 32.

[0024] The biasing device 32 may include a series of connected at-least partial coils 34 (e.g., spring coils). In one embodiment, coils 34 are full coils (full 360°). In another embodiment, coils 34 are partial coils that do not extend completely around rod 12 but instead subtend an angle of less than 360° and each pair of neighboring partial coils are connected by a connection member 36. As seen in FIG. 3, the connection members 36 are separated from one another by a circumferential gap 38.

[0025] If biasing device 32 includes partial coils 34, it can be placed directly over any axial portion of rod 12 as opposed to full coils which have to be slipped over an end of rod 12 and then slid axially to a desired axial position (a device with full coils can be supplied by the manufacturer. This feature allows adding biasing device 32 to device 10 even after device 10 has been installed in a patient.

[0026] A first end 40 of biasing device 32 is arranged to abut against housing 16 and a second end 42, opposite to the first end 40, is provided with a fastener 44, such as a set screw to affix the second end 42 to rod 12. The axial fixation of the second end 42 determines the pretension of biasing device 32.

[0027] After installation of device 10 in a patient, in a typical treatment plan, the biasing device 32 provides an urging force to the opposite ends of device 10, such as to help straighten the patient's spine.