The present invention relates generally to anchoring structures for orthopedic devices, and particularly to a connector assembly for connecting rods and the like to bone anchoring elements, such as pedicle screws.
Many spinal fixation systems are found in the prior art for fixing connecting rods and the like to pedicle screws. Some systems have a disadvantage in that the rod must be bent after coupling to the pedicle screw because of anatomical considerations. Some systems attempt to solve this problem with different kinds of connectors that secure the rod to a polyaxial pedicle screw head and permit spatial adjustments before locking the rod in place. It is imperative to lock the connecting rod with respect to the pedicle screw (or any other kind of bone anchoring element) in order to prevent loosening of the spinal fixation system that could have undesirable consequences to the patient. Nevertheless, no design is free of problems and there is still a need for a connector that is “user-friendly” and permits adjustments before locking the rod in place.
The present invention seeks to provide an improved connector for connecting rods and the like to bone anchoring elements, such as pedicle screws, as is described more in detail hereinbelow. The connector of the invention permits rotational and translational adjustments before locking the rod in place.
There is thus provided in accordance with an embodiment of the present invention a connector assembly including a bone anchoring element, an articulating interface element including a bone-anchoring-element interface portion extending from a connecting-element interface portion, the bone-anchoring-element interface portion including a plurality of resilient fingers adapted to resiliently clamp on the bone anchoring element, and wherein the connecting-element interface portion includes a pair of arms that define a channel for receiving therein a connector element, a ring placed over the articulating interface element on the bone-anchoring-element interface portion, and a cap member that fastens on to the arms.
The connector assembly may further include a connector element received in the channel, wherein the cap member is tightened against the connector element to force the connector element against the ring, which causes squeezing of the fingers to clamp them on the bone anchoring element. In this embodiment, there is no contact between the connector element and the spherical head of the bone anchoring element.
The resilient fingers may be spaced around a longitudinal axis of the articulating interface element. The resilient fingers may have a wedge portion that flares conically outwards. The arms may define a U-shaped channel. The upper portion of the arms may be threaded, and the cap member may threadedly fasten on to the upper portion of the arms.
The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:
Reference is now made to
In a non-limiting embodiment of the invention, the bone anchoring element 12 includes a threaded mechanical fastener (for example, without limitation, a pedicle screw, a pedicle anchor device, a blocking screw for a pedicle anchoring device or any other device for attachment to the pedicle, vertebral body or any other bone) having a spherical proximal portion 14 (also referred to as a spherical head 14) and a (pointed) distal portion 16. Alternatively, bone anchoring element 12 can be a hook or other mechanical fastener with a spherical head. The spherical head 14 may be formed with a socket for an Allen wrench or the like.
Reference is now made additionally to
Reference is now made to
A ring 50 (
The connector assembly 10 may be constructed of any suitable, medically safe material, such as but not limited to, stainless steel alloy (e.g., AISI 316L), titanium or titanium alloy or chrome cobalt alloy, PEEK, shape memory alloys or polymers, including resorbable materials, or any combination of the above. Any material may be coated, such as with HA, any factors or substances including active or passive antibiotics, etc. Different parts of connector assembly 10 may be constructed of different materials with different resilience or hardness, or of the same material but treated to have different resilience or hardness.
The connector element 40 is illustrated as a rod with a cylindrical cross section. However, the invention is not limited to this construction, and connector element 40 may be any slender elongate element, such as but not limited to, a bar of hexagonal, rectangular or square cross section, a rod of elliptical cross section, and many others.
Assembly of connector assembly 10 is straightforward and easy. After bone anchoring element 12 (e.g., pedicle screw) is in place, the user places the bone-anchoring-element interface portion 20 of articulating interface element 18 over spherical head 14 of bone anchoring element 12. Ring 50 is then placed over articulating interface element 18 and sits against wedge portion 28. The connector element 40 is placed in U-shaped channel 34 of connecting-element interface portion 22. Cap member 42 is then tightened to tighten central hub 48 against connector element 40. This forces connector element 40 against ring 50, which presses wedge portion 28 and squeezes fingers 24 to clamp them on spherical head 14 of bone anchoring element 12. There is no contact between connector element 40 and spherical head 14 of bone anchoring element 12.
Reference is now made to
The connector assembly 60 may include an articulating interface element 62 that includes a bone-anchoring-element interface portion 64 extending from a connecting-element interface portion 66. Bone-anchoring-element interface portion 64 may include a plurality of resilient fingers 68 spaced around a longitudinal axis thereof. Resilient fingers 68 may have a wedge portion 70 that flares conically outwards. The inside surfaces of resilient fingers 68 define a clamping portion that resiliently clamps on spherical head 14 of bone anchoring element 12. Connecting-element interface portion 66 may include a pair of arms 72 that define a channel 74, shaped to receive therein connector element 40. The upper portion of arms 72 is threaded to receive cap member 42.
Assembly of connector assembly 60 is straightforward and easy. The user places the bone-anchoring-element interface portion 64 over spherical head 14 of bone anchoring element 12. Ring 50 is then placed over articulating interface element 62 and sits against wedge portion 70. The connector element 40 is placed in channel 74 of connecting-element interface portion 66. Cap member 42 is then tightened to tighten central hub 48 against connector element 40. This forces connector element 40 against ring 50, which presses wedge portion 70 and squeezes fingers 68 to clamp them on spherical head 14 of bone anchoring element 12. There is no contact between connector element 40 and spherical head 14 of bone anchoring element 12.
The embodiment of
Reference is now made to
Connector assembly 80 differs from connector assembly 60 in that connector assembly 80 employs a ring 82 that not only contacts wedge portion 70 but also extends upwards for abutting against the bottom edge of cap member 42. When cap member 42 is tightened to tighten central hub 48 against connector element 40, cap member 42 also pushes down against ring 82, which presses wedge portion 70 and squeezes fingers 68 to clamp them on spherical head 14 of bone anchoring element 12. Thus cap member 42 directly pushes wedge portion 70 and not indirectly through connector element 40. There is contact between connector element 40 and spherical head 14 of bone anchoring element 12.
Reference is now made to
The connector assembly 90 may include an articulating interface element 92 that includes a bone-anchoring-element interface portion 94 extending from a connecting-element interface portion 96. Bone-anchoring-element interface portion 94 may include a plurality of resilient fingers 98 spaced around a longitudinal axis thereof. Resilient fingers 98 may have a wedge portion 100 that flares conically outwards. The inside surfaces of resilient fingers 98 define a clamping portion that resiliently clamps on spherical head 14 of bone anchoring element 12. Connecting-element interface portion 96, unlike the previous embodiments, is offset from the longitudinal axis of bone anchoring element 12. Connecting-element interface portion 96 may include a pair of arms. One arm 102 extends sideways from wedge portion 100 of articulating interface element 92. Another arm 104 has one portion that fits over arm 102 to define a channel 106, shaped to receive therein connector element 40. Another portion of arm 104 sits against wedge portion 100. An upper portion 108 of connecting-element interface portion 96 is threaded to receive cap member 42.
Assembly of connector assembly 90 is straightforward and easy. The user places the bone-anchoring-element interface portion 94 over spherical head 14 of bone anchoring element 12. The connector element 40 is placed in channel 106 on arm 102 of connecting-element interface portion 96. Arm 104 is then placed over connector element 40 and sits against wedge portion 70. Cap member 42 is then tightened to tighten arm 104 against connector element 40. Arm 104 also presses wedge portion 100 and squeezes fingers 98 to clamp them on spherical head 14 of bone anchoring element 12. There is no contact between connector element 40 and spherical head 14 of bone anchoring element 12. It is noted that arm 104 may be hinged to arm 102 or connected with an extra fastener (e.g., screw) for improved locking.
Reference is now made to
The connector assembly 120 may include an articulating interface element which is shaped and also referred to as an internal finger ring 122. Finger ring 122 includes a bone-anchoring-element interface portion 124 extending from a connecting-element interface portion 126. Bone-anchoring-element interface portion 124 may include a plurality of resilient fingers 128 spaced around a longitudinal axis thereof. Resilient fingers 128 may have a wedge portion 130 that flares conically outwards. Fingers 128 define a clamping portion that resiliently clamps on spherical head 14 of bone anchoring element 12. Connecting-element interface portion 126 may include a pair of arms 132 that define a channel, shaped to receive therein connector element 40. The upper portion of arms 132 is threaded to receive cap member 134. A ring 136 is placed around fingers 128.
In the assembly of connector assembly 120, instead of the ring wedging against the wedge portion of the fingers as in the previous embodiments, the opposite is true. By tightening cap member 134 against connector element 40, fingers 128 and wedge portion 130 are forced and wedged outwards against the internal circumference of the rigid ring 136. This internal wedging force tightens fingers 128 and wedge portion 130 against spherical head 14.
Reference is now made to
Reference is now made to
The connector assembly 160 may include an articulating interface element 162 that includes a bone-anchoring-element interface portion 164 extending from a connecting-element interface portion 166. Bone-anchoring-element interface portion 164 may include a plurality of resilient fingers 168 spaced around a longitudinal axis thereof. The articulating interface element 162 is disposed inside a wedging ring 170, which has an upper end that is threaded to receive cap member 42. The action of tightening cap member 42 onto ring 170 causes cap member 42 to press against connector element 40 and force articulating interface element 162 with its fingers 168 to move downwards with respect to wedging ring 170. This action wedges and forces fingers 168 against spherical head 14.
The connector assemblies of the invention permit rotational adjustments of the articulating interface element with respect to the spherical head of the bone anchoring element and translational adjustments of the connector element before locking the connector element in place.
It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art.