Surgical instrument for positioning a spinal rod

A surgical instrument including an elongate member, a support for engaging a rod receiving element, and a connection between the elongate member and the support. This connection comprises a pivotal articulation, and the elongate member is connected to the support via the pivotal articulation so as to be able to pivot independently around at least two perpendicular axes. The elongate member is also longitudinally movable with respect to the support. The elongate member has, at a first end, a device for holding a rod.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of European Patent Application No. 10306349.1, filed on Dec. 3, 2010.

TECHNICAL FIELD

The systems devices and methods in the present disclosure relate to a surgical instrument and in particular to a surgical instrument for introducing a rod in a rod receiving element of an orthopaedic device.

One field of application for this instrument is the assembly of orthopaedic devices for holding bones in a relative position, for example to aid in the healing of breaks or the positioning of bones in the treatment of spinal deformities or spinal degenerative diseases or trauma diseases, or otherwise to correct abnormal curvatures of the spine. Other bone deficiencies and abnormalities may also benefit from embodiments of the invention.

BACKGROUND

The spine is formed of superposed vertebrae, normally aligned along a vertebral axis, from the lumbar vertebrae to the cervical vertebrae, each having a posterior wall from which projects a spinous process and two lateral edges from the walls of which there project ribs and/or transverse processes and/or lamina. If the spine of a person has abnormal curvature, the vertebrae are typically inclined relative to one another and relative to the vertebral axis.

In order to straighten the vertebral column as a remedy for this situation, the lateral edges of the vertebrae on the concave side can be moved away from one another and supported at distances from one another substantially equivalent to the distances between the lateral edges on the other side. Devices known in the art for holding the vertebrae relative to one another include rods that are held by rod-receiving elements attached to the vertebrae, for example using screws, hooks, or flexible ligatures.

The assembly of the rods to the rod receiving elements is normally carried out, in the operating theatre, after the rod-receiving elements have been surgically anchored to an osseous structure of the patient. It is therefore a delicate operation requiring significant skill. In order to facilitate it, it is known in the art to use specialised surgical instruments, such as a so-called persuader, which is a surgical instrument comprising an elongate member with, at a first end, a device for holding the rod substantially transversally to the elongate member. While such a persuader is adequate for pushing the rod in the direction of the elongate member, it is less useful for translating the rod laterally, that is, perpendicularly to both this elongate member and the rod. This is a significant drawback in particular when the rod-receiving elements are not top- but side-loading, and therefore require a lateral translation of the rod to properly engage it.

Another surgical instrument has been proposed, which is sold by Medtronic under the trade name CD Horizon® Legacy™ 5.5 Translator Rod Pusher, and comprises comprising an elongate member with a support for engaging a rod receiving element, and a hinged connection between the support and the elongate member. The elongate member comprises, at its distal end, a device for holding a rod to be introduced into the rod-receiving element.

SUMMARY

A first object of the disclosure is that of providing a surgical instrument which allows an easier and more accurate and reliable lateral positioning of the rod, in particular with respect to the rod-receiving element.

Accordingly, in at least one illustrative embodiment, a surgical instrument according to the present disclosure comprises an elongate member with, at a distal first end, a device for holding a rod, a support for engaging a rod receiving element, and a connection between the support and the elongate member, the connection comprising a pivotal articulation, wherein the elongate member is connected to the support via the pivotal articulation so as to be able to pivot independently around at least two non-coincident, and in particular perpendicular axes, and is also movable along its longitudinal axis with respect to the support.

Consequently, the support is freely orientable with respect to the rod-receiving element, facilitating its use and simplifying the assembly of the orthopaedic device.

In some embodiments, the support comprises pliers for grasping the rod receiving element at a distal end of the pliers. As a result, the support can be secured in all directions with respect to the rod-receiving element, facilitating even more its use and allowing the user to translate the rod in various directions without the concerning of losing its support on the rod-receiving element.

In particular, the pliers may be biased towards a closed position, further ensuring their grasp on the rod-receiving element.

In some exemplary embodiments, two arms of the pliers converge towards the distal end of the pliers, forming a tapering passage between them so that, in use, the rod is embraced between these two arms of the pliers and centered towards the rod receiving element when it is pushed distally by the elongate element.

In further exemplary embodiments, the articulation releasably connects the elongate member to the support, in particular via a releasable form-locking connector, such as, for example, releasable form-locking connector comprises a sliding bolt biased towards a closed position in which the form-locking connector is engaged, possibly with a push button for sliding the bolt from the closed position to an open position in which the form-locking connector is disengaged. Alternatively, the releasable form-locking connector may comprise a rotating lock. The elongate element can thus be eventually released from its support, on a specific user command, for further flexibility in its use.

Within the context of the present specification, it must be understood that by “independently pivotable around at least two non-coincident, and in particular perpendicular axes”, it is not meant that the articulation necessarily comprises two distinct physical axles, as in a Cardan joint. In particular, in at least some embodiments, these two degrees of freedom in rotation of the articulation are provided in a particularly simple and reliable manner by a ball-and-socket joint. In particular, the articulation may further comprise an inner screw thread within a through hole in a ball element of the ball-and-socket joint, the inner screw thread being engaged with an outer screw thread of the elongated member, and the ball-and-socket joint being lockable in rotation in the longitudinal axis of the elongated member, in particular by a longitudinal load in a direction of the axis. The longitudinal motion of the elongated member can thus be actuated, through the screw connection, by a relative rotation of the elongated member around its longitudinal axis. To actuate this rotation, the elongate member may in particular comprise a handle at a second end opposite to the first end.

In some of these embodiments, the inner screw thread is formed in an inner surface of a tube held within the through hole in the ball element. The length of the inner screw thread in engagement with the outer screw thread of the elongated member can therefore be increased, reducing the friction between the screw threads, in particular while the elongated member is being pushed to lock the ball-and-socket joint. The reliability and usability of the surgical instrument is thus improved.

Another object of the disclosure is that of providing a method for introducing a rod into a rod receiving element of an orthopaedic device, wherein the rod is held at a first end of an elongate member which is connected to a support via an articulation, the support is fixed to the rod receiving element, the elongate member is pivoted at the articulation and moved longitudinally with respect to the support in order to insert the rod into the rod receiving element.

The above summary of some example embodiments is not intended to describe each disclosed embodiment or every implementation of these embodiments. In particular, selected features of any illustrative embodiment or combination of embodiments within this specification may be incorporated into an additional embodiment unless clearly stated to the contrary.

DETAILED DESCRIPTION

A bone fixing system comprising at least one rod linking a plurality of rod receiving elements may be installed in a patient to hold or fix one structure in a selected relation with one or more other structures. As used herein, the term structure may refer to bones, portions of bones, or bone implants, as well as rods, elongated members, plates, or other implanted man-made devices. Such a bone fixing system may be installed using a minimally invasive surgery (MIS) procedure.

Such bone fixing systems are useful in repairing broken bones, correcting curvatures of the spine and for other surgical procedures that hold structures (e.g., bones) in a fixed relative position. They can be particularly useful for minimally invasive surgery (MIS) procedures, which can reduce trauma to soft tissue due to the relatively small incision made in a patient. For example, a surgical procedure may be performed through a 2 cm to 4 cm incision formed in the skin of the patient. Dilators, a targeting needle, and/or a tissue wedge may be used to provide access to structures without the need to form a larger incision with a scalpel through muscle and other tissue. A minimally invasive surgery (MIS) procedure may reduce an amount of postoperative pain felt by a patient as compared to invasive procedures. A minimally invasive procedure may also reduce recovery time for the patient as compared to invasive procedures. In some embodiments, the natural flexibility of skin and soft tissue may be used to limit the length and/or depth of an incision or incisions needed during the procedure. Minimally invasive procedures may provide limited direct visibility in vivo.

Such bone fixing systems may be used to correct problems due to spinal injury, deformity, or disease. For example, various bone fixing systems of this type may be used from the C1 vertebra to the sacrum to correct spinal problems. For example, a bone fixing system may be implanted posterior to the spine to maintain distraction between adjacent vertebral bodies in a lumbar portion of the spine. It may be useful for holding tendons, bones, or muscles during the healing process and may be implanted using MIS procedures and thus it is in this context that embodiments of the disclosure may be described. It will be appreciated, however, that bone fixing systems of this type may be applicable for stabilizing other areas of the body.

During surgery, at least some of the rod-receiving elements are first anchored to the underlying structure first, and then receive the rod. Maneuvering the rod, however, especially during MIS, is difficult and will often require a specific surgical instrument.

Components of surgical instruments in accordance with the disclosure may be made of materials including, but not limited to, titanium, titanium alloys, stainless steel, ceramics, and/or polymers. Some components of a surgical instrument may be autoclaved and/or chemically sterilized. Components that may not be autoclaved and/or chemically sterilized may be made of sterile materials. Components made of sterile materials can be used with other sterile components during assembly of a surgical instrument and of a bone fixing system.

An embodiment of a surgical instrument1according to the invention is illustrated inFIGS. 1 and 2. This surgical instrument1comprises pliers2with two arms3,4connected by a hinge5with a hinge axis X. Each arm3,4is prolonged beyond the hinge5by a handle6,7. A coil spring8between the handles6,7biases the handles6,7apart from each other, and the arms3,4towards each other and to a closed position of the pliers2, while a rack24can be used to lock the handles6,7, and therefore the arms3,4at any one of a plurality of predetermined angular positions with respect to each other. The handles6,7allow a user to open the pliers by unlocking the rack24and pushing the handles6,7towards each other. A ball-and-socket articulation9is connected to the pliers2over a releasable connector10. The ball-and-socket articulation9holds an internally screw-threaded tube11which is thus rotatable, with respect to the pliers2, around the center of the ball-and-socket articulation9. The surgical instrument also comprises an externally screw-threaded elongate member12with a rod holder13at a distal end and a handle14at a proximal end, wherein the screw thread44of the elongate member12is in engagement with the screw thread42of the tube11. In some examples, rod holder13is connected to elongate member12by pivotal and/or rotatable connection46.

FIG. 3illustrates the ball-and-socket articulation9with the internally screw-threaded tube11. The tube11is press-fit within an orifice15athrough the ball element15of the ball-and-socket articulation9. A square-section shaft17with a transversal orifice17aprotrudes from one side of the annular socket16to provide the connection with the releasable connector10. The friction between the ball element15and the socket16is such that, while the ball is normally freely rotatable within the socket16, it can be frictionally locked by an axial load in the axis Z of the tube11, as may be exerted by a user pushing on the elongate member12through the handle14. Therefore, the elongate element12can normally be tilted around the two axes X, Y of the articulation9which are orthogonal to Z, but also advanced or retreated, along axis Z, with respect to the articulation9, by a combined axial load and rotation exerted through the handle14at its proximal end.

FIGS. 4 and 5illustrate the assembly of the ball-and-socket articulation9. Because of the part-spherical shape of the socket16, its top and bottom openings16a,16bare narrower than an outer diameter D of the ball element15. To be able to insert the ball element15into the socket16, the ball element15presents a narrower width d in a plane perpendicular to the orifice15a. Once the ball element15is inserted into the socket16as shown inFIG. 4, it can be tilted to align the orifice15awith the top and bottom openings16a,16bof the socket16. The screw-threaded tube11can then be press-fit into the orifice15a.

FIG. 6shows the releasable connector10of the articulation9to the pliers2. The shaft17is received in a complementary recess18, wherein it is held by a sliding bolt19going through the orifice17a. The bolt19is coupled to a spring-loaded push-button20, which can be pushed to disengage the pin19from the orifice17aand so release the articulation9from the pliers2.

FIGS. 7 to 10illustrate the use of the surgical instrument1to bring a rod21into a top-loading receiving portion22of a rod receiving element23anchored to an osseous structure in a patient. In a first step illustrated inFIG. 7, the operator engages the rod receiving element23with the pliers2, locking the arms3,4with the ratchet24. He can then engage the rod21with the rod holder13and tilt the elongate member12around the articulation9, as shown inFIG. 8, until aligning the rod21with the receiving portion22. From this position, as shown inFIG. 9, simultaneously pushing and rotating the handle14will push the rod21downwards into the receiving portion22. With the rod21in the receiving portion22, as shown inFIG. 10, the elongate member12can still be tilted around the articulation9to adjust the orientation of the rod21.

While the method illustrated inFIGS. 7 to 10applies to a rod receiving element23with a top-loading receiving portion22, this surgical instrument1can also be particularly useful for side-loading rods into rod receiving elements23. In this case, after engaging the rod21with the rod holder13and the rod receiving element23with the pliers2, locking the arms3,4with the rack24, and maneuvering the elongate member12to longitudinally align the rod21with the receiving portion22of the rod receiving element23, the elongate member12is tilted around the articulation9to introduce the rod21longitudinally into the side-loading rod receiving element23, as shown inFIG. 11.

While in the methods illustrated inFIGS. 7 to 11the pliers grasp the rod receiving element23substantially transversally to the receiving portion22, the pliers may also grasp the rod receiving element23in a substantially parallel direction to the receiving portion22, as shown inFIG. 12. For this, a surgical instrument1′ according to a second embodiment of the invention may be particularly advantageous, in which the releasable connector10′ is laterally offset with respect to the axis X′ of the hinge5′ of the pliers2′, as shown inFIG. 12. In particular, as shown in this drawing, the surgical instrument1′ may comprise two releasable connectors10′, each one offset to one side of the axis X′.

Each releasable connector10′ also differs from that of the first illustrated embodiment in that the closing member is not a sliding bolt operated by a push button, but a rotating lock19′ operated by wings20′. As illustrated inFIG. 13, in this embodiment, in order to connect the articulation9′ to the pliers2′, a square-section protrusion17′ of the articulation9′ is introduced vertically into a complementary recess18′ within the releasable connector10′, with the rotating lock19′ in an open position, like the right-hand releasable connector10′ ofFIG. 13. To lock the protrusion17′ within the recess18′, the rotating lock19′ is rotated to a closed position, like that of the left-hand releasable connector ofFIG. 13. The articulation9′ is thus secured with respect to the pliers2′. To release it again, the rotating lock19′ may then be rotated back into the open position.

Those skilled in the art will recognize that the invention may be manifested in a variety of forms other than the specific embodiment described and contemplated herein. Accordingly, departure in form and detail may be made without departing from the scope of the systems, devices and methods of the present disclosure as described in the appended claims.