Patient-specific navigation guide for spinal surgery

Abstract

A patient-specific navigation guide for use in spinal surgery comprises: a bearing frame having an arcuate shape with two arms, each having a respective patient-specific contact area, each configured to rest on a respective contact area of a patient's vertebra, in order to define a unique coupling configuration; a single main guide sleeve, positioned at one side of the bearing frame, extending longitudinally between a proximal end and a distal end and having a central hole passing axially through the longitudinal extension of the main guide sleeve itself, for guiding a surgical instrument on a patient's vertebra. The main guide sleeve has, near the proximal end, a respective patient-specific contact surface to abut on an area of the patient's vertebra, on which the operation is to be performed, in a coupling configuration. The guide also comprises at least one stiffening element placed between the two arms and provided with at least one central portion designed to override, with or without contact, a spinous process of the vertebra. In addition, the guide comprises a bridge-joining element extending between the two arms and placed in a position between the contact areas of the arms with the vertebra and the central portion of the stiffening element that overrides the spinous process. The two arms comprise a bearing arm connected to the main guide sleeve and a resting arm with no connection to its own guide sleeve.

Description

[0001] “PATIENT-SPECIFIC NAVIGATION GUIDE FOR SPINAL SURGERY” TECHNICAL FIELD

[0002] The present invention relates to the technical field of orthopaedic surgery. More specifically, the invention relates to a patient-specific navigation guide that can be used in spinal surgery.

[0003] Patient-specific guides are disposable templates, which are individually designed to match the anatomy of the bone derived from computed tomography images of a given patient. Surgical operations such as perforations and cuts can be planned pre-operatively using computer- assisted technology, and the resulting patient-specific guides subsequently allow the surgeon to accurately replicate the planned operations on the patient's body.

[0004] Patient-specific guides have been used in various fields of orthopaedic surgery, including spinal surgery.

[0005] In this field, patient-specific guides are mainly used to help the surgeon during the insertion of the pedicle screw, so that the screw can be inserted into the bone structure according to a pre-planned optimal insertion direction.

[0006] PRIOR ART

[0007] Examples of patient-specific guides are known from patents EP 2749235, EP 2502582, US 8758357, WO 2014 / 090908, EP3863532, WO 2013 / 158521 , WO 2014 / 197844 o even WO2014 / 070889.

[0008] As is known in the state of the art, navigation guides comprise two or more tubular guide members integral with a bearing frame.

[0009] The two tubular guide members define the insertion axes for two pedicle screws, which can be inserted into the patient's vertebra at an angle planned in the pre-operative phase. The insertion axes correspond to the longitudinal axes of the tubular guide members. Therefore, tubular guide members have an axial through cavity from where a surgical instrument can be inserted, for example in order to prepare the pedicle to receive the pedicle screw.

[0010] The guides currently used for such operations have rather large dimensions with two or more tubular guide members, having to operate simultaneously on several points of the same vertebra or even on adjacent vertebrae.

[0011] As the preference in recent years in spinal surgery is to proceed by means of minimally invasive surgery, the tendency is to minimise the size of the wound.

[0012] With the guides currently known and used, the cut must be rather extensive in order to widen the wound, insert and position the guide in the correct position.

[0013] If the cut is extensive, surgery can no longer be defined as minimally invasive, resulting in longer operating and recovery times for the patient during convalescence. Moreover, if such a cut extends to particularly mobile areas of the skin, such as near the coccyx, the wound will struggle to heal.

[0014] An object of the present invention is to overcome the drawbacks of the prior art. In particular, the object of the present invention is to propose a patient-specific navigation guide that is compact and can be used in minimally invasive surgery and on any vertebra.

[0015] A further object of the present invention is to provide a patient-specific navigation guide that allows the screws to be inserted safely and accurately even with difficult trajectories, without continuous control with radii, and even in different positions on the same side of the vertebra.

[0016] It is also the object of the present invention to provide a patient-specific navigation guide that can provide simplified positioning on the patient's bone structure in a stable and safe manner.

[0017] These and further objects and advantages are achieved by a patientspecific navigation guide according to the appended claims and a patientspecific navigation kit according to claim 11 . SUMMARY

[0018] A first aspect of the present invention provides for a patient-specific navigation guide for use in spinal surgery, comprising a bearing frame having an arcuate shape with two arms, each having a respective patientspecific contact area, each configured to abut on a respective contact area of a patient’s vertebra, in order to define a unique coupling configuration.

[0019] The two arms comprise a bearing arm, connected to its own guide elements, and a resting arm, with no connection to its own guide elements.

[0020] There is a single main guide sleeve, positioned at one side of the bearing frame and connected only to the bearing arm, extending longitudinally between a proximal end and a distal end and having a central hole passing axially through the longitudinal extension of the main guide sleeve itself, for guiding a surgical instrument on a patient's vertebra.

[0021] The main guide sleeve has, near the proximal end, a respective patientspecific contact surface to abut on an area of the patient's vertebra, on which the operation is to be performed, in a coupling configuration.

[0022] The guide also comprises at least one stiffening element placed between the two arms and provided with at least one central portion designed to override, with or without contact, a spinous process of the vertebra to be operated on.

[0023] In addition, the guide comprises at least one bridge-joining element extending between the two arms and placed in a position between the contact areas of the arms with the vertebra and the central portion of the stiffening element that overrides the spinous process.

[0024] Preferably, the joining element has an arcuate conformation with a concavity directed towards the guide itself. The joining element protrudes transversely with respect to a plane passing through the longitudinal axes of the arms of the bearing frame.

[0025] The stiffening element has a substantially V-shaped conformation with the concavity directed towards the vertebra. The guide also comprises at least one support foot, protruding from one of the arms of the bearing frame, to give sagittal stability to the guide itself.

[0026] The support foot comprises a spherical tip, adapted to be accommodated in hollows of the vertebra.

[0027] Advantageously, the support foot protrudes from the arm bearing the main guide sleeve, the arm being more unstable as a result of the stress caused by the passage of surgical instruments.

[0028] The guide comprises at least one auxiliary guide sleeve, which is connected to the bearing arm of the bearing frame by means of a support extending protruding from the bearing arm, transversely with respect to a plane passing through the longitudinal axes of the bearing frame arms.

[0029] The auxiliary guide sleeve extends longitudinally between a proximal end and a distal end, with its axis being inclined with respect to the longitudinal axis of the main guide sleeve; the auxiliary guide sleeve has a central hole passing axially through the longitudinal extension of the auxiliary guide sleeve itself, to guide a surgical instrument on a patient's vertebra.

[0030] Advantageously, the guide comprises a plurality of auxiliary guide sleeves, aligned in sequence on the same support and having longitudinal axes inclined with respect to one another.

[0031] Preferably, the guide comprises a gripping element placed at the top of the bearing frame, which can be positioned above the central portion of the stiffening element.

[0032] A second aspect of the present invention provides a patient-specific navigation guide kit comprising two navigation guides wherein a first guide has a main guide sleeve associated with one arm of the bearing frame, and a second navigation guide has a guide sleeve associated with the other arm placed on the opposite side of the bearing frame, in order to be able to operate on two opposite sides of the same vertebra. The two navigation guides each have a respective bearing arm connected to a respective main guide sleeve; the bearing arms are located on opposite sides of each navigation guide. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] A patient-specific navigation guide as described and claimed is also illustrated in the following figures, which are illustrative and not exhaustive, wherein:

[0034] - Figure 1 is a perspective view of a patient-specific navigation guide in accordance with the present invention, associated with a vertebra to be operated on and according to a first embodiment;

[0035] - Figure 2 is a perspective view of a specific navigation guide associated with a vertebra to be operated on and according to a second embodiment, which involves a technical modification to the first embodiment;

[0036] - Figure 3 is a bottom view of the guide shown in Figure 1 ;

[0037] - Figure 4 is a front view of the guide shown in Figure 2;

[0038] - Figure 5 is a perspective view of a patient-specific navigation guide in accordance with the present invention and in accordance with a third embodiment involving a technical variant with respect to the first embodiment; solely by way of example;

[0039] - Figure 6 is the second guide, which, together with the guide illustrated in Figure 5, makes up the kit of the present invention and according to a possible embodiment, in particular according to the third embodiment;

[0040] - Figure 7 is a perspective view from below of the guide shown in Figure 5;

[0041] - Figure 8 is a top view of the guide shown in Figure 7;

[0042] - Figure 9 is a front view of the guide in accordance with a fourth embodiment, given by the composition of the technical variants incorporated together on the first embodiment;

[0043] - Figure 10 is a top view of the guide of the present invention according to a fourth embodiment; - Figure 11 is a front view of the guide of the present invention according to the first embodiment and in a use configuration associated with a different vertebra from that illustrated in Figures 1 and 2.

[0044] DESCRIPTION

[0045] With reference to the accompanying figures, 1 indicates a patient-specific navigation guide in accordance with a first aspect of the present invention. The guide 1 comprises a bearing frame 2 which may preferably have an arcuate inverted U-shape, as illustrated in the accompanying figures, or an inverted V-shape, with two resting arms 3. Each arm 3 comprises a respective contact area 4 that is conformed according to the specific patient; in other words, each contact area 4 is configured to rest on a respective contact area of a patient's vertebra 100 in order to define a unique coupling configuration that conforms to the patient's anatomy.

[0046] In this way, the guide 1 presents optimal stability by having not discrete resting points but two extended surfaces, each configured according to the anatomy of the specific patient.

[0047] The two arms 3 are, in particular, a bearing arm 3’ and a resting arm 3”.

[0048] The bearing arm 3’ is connected to other functional elements of the guide (such as guide sleeves described below), while the resting arm 3” has no connection to other functional elements of the guide, but at most is connected to structural elements and only has the function of an additional resting point on the vertebra, to balance the force applied by the surgeon on the guide itself and distribute it evenly over the vertebra. In other words, the resting arm 3” is not connected to any guide sleeve or other functional elements: it is only connected to other structural elements such as to the bearing arm 3’, via the frame 2 or via a joining element 8 described below, and possibly to a further resting element as described below. Only one side of the bearing frame 2, thus associated with only one arm 3, in particular the bearing arm 3’, has a guide sleeve 5.

[0049] The other arm 3, the resting arm 3” which is opposite the one connected to the guide sleeve 5, is not connected to any other guide sleeve: it therefore has no connection to its own guide elements. This resting arm 3” has only the contact area 4 below, for resting on the patient's vertebra. Therefore, in this configuration, it appears that the guide sleeve 5 is only arranged on one side of the bearing frame 2, with respect to a plane orthogonal to the plane passing through the two arms 3.

[0050] The first arm 3 or bearing arm 3’ is a support arm for further guide elements such as guide sleeve 5 and others described below; this bearing arm 3’ also has, of course, a resting part for the guide on the vertebra: the contact area 4 below. The second arm 3, or resting arm 3”, on the other hand, is only a resting arm, thus not having any guide sleeve or other connections to other elements of the guide.

[0051] The guide sleeve 5 extends longitudinally between a proximal end 5p and a distal end 5d and has a central hole 6 passing axially through the longitudinal extension of the sleeve 5 itself. This guide sleeve 5 is used to guide a surgical instrument on a patient's vertebra 100.

[0052] The guide sleeve 5 also has, at the proximal end 5p, a respective patient contact surface specifically designed to abut on an area of the patient's vertebra 100 on which the operation is to be performed.

[0053] Between the two arms 3 of the bearing frame 2, at least one stiffening element 7 is provided, comprising at least one central portion 7a intended to override, with or without contact, a spinous process 104 of the vertebra 100 on which the operation is to be performed. This stiffening element 7 is preferably placed immediately below the bearing frame 2. In particular, it is placed below the top 2a of the bearing frame 2.

[0054] Preferably, the stiffening element 7 has a substantially V-shaped conformation with the concavity directed towards the vertebra 100.

[0055] Advantageously, the guide 1 also comprises at least another structural element, such as a joining element 8, preferably a bridge, extending transversely to the two arms 3 in order to connect them rigidly. More preferably, the joining element 8 is located in a position comprised between the contact areas 4 of the arms 3 with the vertebra 100 and the central portion 7a of the stiffening element 7 that overrides the spinous process 104.

[0056] This joining element 8 is therefore a crosspiece, preferably not straight, which extends between the two arms 3 to distance them and keep them firmly in a predetermined mutual position.

[0057] Preferably, the joining element 8 has an arcuate or counter-shaped conformation to the spinous process 104 it embraces, with concavity directed towards the guide itself; in other words, the joining element 8 is transverse to a plane passing through the longitudinal axes 3a of the arms 3 of the bearing frame 2.

[0058] In accordance with some embodiments, the joining element 8 assumes an arcuate conformation so as to define, within itself, a seat 88 for housing the spinous process 104 of the vertebra 100.

[0059] The bearing frame 2 advantageously has at least one support foot 10, protruding from one of the arms 3, to give sagittal stability to the guide itself. Depending on the vertebra to be operated on, and consequently the size of the guide to be used, there may also be two support feet 10, one for each arm 3. The support feet 10 have a contact surface with the vertebra shaped according to the specific patient, i.e. shaped like the negative of the vertebra on which they are to rest, for greater stability.

[0060] In some configurations, preferably for guides dedicated to operations on the sacral vertebrae, the support foot 10 has a spherical tip 11 (as shown in Figures 2 and 4), which is adapted to be accommodated in hollows of the vertebra 100. Preferably, the support foot 10 always protrudes at least from the bearing arm 3 bearing the main guide sleeve 5, the side with the sleeve being the one most subject to stress because it is the one on which the surgeon operates. According to some embodiments, as illustrated in Figures 5-8, the guide 1 also comprises at least one auxiliary guide sleeve 12, which is always connected to arm 3 bearing the main guide sleeve 5, then connected to the bearing arm 3’. The auxiliary sleeve 12 is connected to the bearing arm 3’ via a support 13 which protrudes from that arm, transversely to the plane passing through the arms 3 of the bearing frame 2. In this case, it is this support 13 that acts as a support foot: an additional support foot (therefore considered a structural element of the guide and not a functional one) associated with the free arm can then be provided to balance the structure. In such cases, therefore, the foot 10 protrudes from the support arm 3”, the free one, i.e. the arm without main guide sleeve 5 and auxiliary guide sleeves 12, to counterbalance the guide 1.

[0061] The particular configuration, with the main guide sleeve 5 and any auxiliary sleeves 12 all arranged on the same side of the guide, in particular all associated with the same bearing arm 3’, allows a plurality of screws to be inserted on the same side of the vertebra, thus considerably reducing the overall dimensions of the guide itself and, therefore, the size of the wound itself.

[0062] The auxiliary guide sleeve 12 also extends longitudinally between a proximal end 12p and a distal end 12d, with axis 12a inclined with respect to the longitudinal axis 5a of the main guide sleeve 5. The auxiliary guide sleeve 12 also has a central hole 15 passing axially through the longitudinal extension of the auxiliary guide sleeve 12 itself, to guide a surgical instrument on a patient's vertebra 100.

[0063] Other embodiments (Figure 10) involve the presence of a plurality of auxiliary guide sleeves 12, aligned in sequence and with longitudinal axes having different inclinations, placed on the same support 13 protruding from the bearing arm 3’, associated with the main guide sleeve 5.

[0064] Other embodiments, illustrated for example in Figures 9 and 10, involve either support feet with a spherical tip, or auxiliary sleeves. The spherical support 11 is positioned where, for structural stability requirements, a greater grip on the vertebra is required.

[0065] For ease of handling, the bearing frame 2 comprises, substantially on the top 2a, above the central portion 7a of the stiffening element 7 coupled to the spinous process 104 or sacral crest, a gripping element 16, which also serves as a pressure point to keep the guide in a stable position during insertion of the surgical instruments into the guide channels.

[0066] Another aspect of the present invention is to propose a patient-specific navigation guide kit comprising two navigation guides in accordance with the above. Each guide comprises a main guide sleeve positioned on only one of the two arms. Specifically, the kit consists of two guides, one of which has the guide sleeve (and any auxiliary sleeves) on the right arm, and the other guide has the main guide sleeve (and any auxiliary sleeves) on the left arm. In this way, it is possible to operate, alternately and at different times during the operation, on both sides of the vertebra to be operated on.

[0067] The two navigation guides, therefore, each have a respective bearing arm 3’ connected to a respective main guide sleeve 5: the bearing arms 3’ are thus placed on opposite sides of each navigation guide.

[0068] An example of such a kit is shown in Figures 5 and 6, where Figure 5 shows a first guide with the main guide sleeve 5 on the left arm, and Figure 6 shows the second guide of the kit with the main guide sleeve 5 on the right arm.

[0069] The kit depicted in Figures 5 and 6 is shown solely by way of example, as the guides can be made in accordance with any of the described and illustrated embodiments, i.e. at least always with only the main sleeve (connected to one and only one bearing arm 3’) with which the support foot can be integrated, or one or more auxiliary sleeves (also always and only connected to the same bearing arm 3’), or even the combination of the two variants, i.e. With the support foot and auxiliary sleeves.

[0070] The guide according to the present invention allows easy use in minimally invasive surgery due to its small transverse dimensions. The presence of only one main guide sleeve provided on one side of the guide and connected to only one of the two arms, the bearing one, and the other arm still without any further guide elements, allows for a cut with more contained dimensions. The kit itself allows for a contained cut since it comprises two guides of the type described above, each with a main sleeve associated with a single respective and different bearing arm.

[0071] Within the same cut, it is in fact possible to insert a first guide with the guide sleeves located only on one side, e.g. at the bearing arm on the right. Once the guide is in place and stabilised, the surgeon proceeds with the operation. After operating on one side, the guide can be removed and, still in the same cut, the second guide inserted with the sleeves now on the opposite side, so for example associated with the bearing arm on the left, thus operating on the other side of the vertebra. Each guide then has only one support arm, devoid of any connection to guide sleeves or other elements adapted to operate on the vertebra.

[0072] Compared to commonly used guides, the guide according to the present invention, or unilateral guide, has a more contained profile, allowing easy insertion into the cut made in the patient, especially for entry points where the screw trajectories are large, without having to increase the size of the patient incision. This is possible precisely because the main guide sleeve and possibly the auxiliary sleeves are connected to only one arm, the bearing arm, while the other arm, the resting arm, is free from any additional guide elements, thus limiting the overall dimensions of the guide.

[0073] The guides that make up the kit are always produced in two versions, one for drilling the left side and one for the right side. In fact, the footprint of the guide sleeves is only on the affected side of the guide.

[0074] For all unilateral guides, stability is guaranteed due to the contact of the guide on both sides, making it possible to insert the screws safely and precisely. The largest contact area is located on the side of interest or where the operation is to be performed, as this is the side that is most stressed and most prone to instability, and a smaller contact area is present on the opposite side, ensuring good stability during use.

Claims

CLAIMS1. Patient-specific navigation guide (1 ) for use in spinal surgery, comprising:- a bearing frame (2) having an arcuate shape with two arms (3), each having a respective patient-specific contact area (4), each configured to abut on a respective contact area of a patient’s vertebra (100), in order to define a unique coupling configuration; said two arms (3) comprising a bearing arm (3’) connected to its own guide elements and a resting arm (3”), with no connection to its own guide elements;- a single main guide sleeve (5), positioned at one side of said bearing frame (2) and only connected to said bearing arm (3’); said main guide sleeve (5) extending longitudinally between a proximal end (5p) and a distal end (5d) and having a central hole (6) passing axially through the longitudinal extension of the main guide sleeve (5) itself, for guiding a surgical instrument on a patient’s vertebra (100);- said main guide sleeve (5) having, near said proximal end (5p), a respective patient-specific contact surface to abut on an area of said patient's vertebra (100), on which the operation is to be performed, in a coupling configuration;- at least one stiffening element (7) placed between said two arms (3) and provided with at least one central portion (7a) designed to override, with or without contact, a spinous process (104) of the vertebra (100) to be operated on,- at least one bridge-joining element (8) extending between said two arms (3) and placed in a position between the contact areas of the arms (3) with said vertebra (100) and the central portion (7a) of the stiffening element (7) overriding the spinous process.

2. Specific navigation guide according to claim 1 , wherein said joining element (8) has an arcuate shape with a concavity directed towards the guide (1 ) itself; said joining element protrudes transversely with respect toa plane passing through the longitudinal axes of the arms (3) of said bearing frame (2).

3. Specific navigation guide according to claim 1 , wherein the stiffening element (7) has a substantially V-shape conformation with the concavity directed towards the vertebra (100).

4. Specific navigation guide according to claim 1 , comprising at least one support foot (10), protruding from one of the arms (3) of said bearing frame (2), to provide sagittal stability.

5. Specific navigation guide according to the preceding claim, wherein said support foot (10) comprises a spherical tip (11 ), which is adapted to be accommodated in hollows of the vertebra (100).

6. Specific navigation guide according to claim 4, wherein said support foot (10) protrudes from the bearing arm (3’) of said main guide sleeve (5).

7. Specific navigation guide according to claim 1 , comprising at least one auxiliary guide sleeve (12), connected to the bearing arm (3’) of the bearing frame (2) by means of a support (13) extending from said bearing arm (3’) transversely with respect to a plane passing through the longitudinal axes of the arms (3) of said bearing frame (2).

8. Specific navigation guide according to the preceding claim, wherein said auxiliary guide sleeve (12) extends longitudinally between a proximal end (12p) and a distal end (12d), said longitudinal axis (12a) being inclined with respect to the longitudinal axis (5a) of the main guide sleeve (5); said auxiliary guide sleeve (12) having a central hole (15) passing axially through the longitudinal extension of the auxiliary guide sleeve (12) itself, to guide a surgical instrument on a patient’s vertebra (100).

9. Specific navigation guide according to the preceding claim, wherein there are a plurality of auxiliary guide sleeves (12) aligned sequentially on the same support (13).

10. Specific navigation guide according to any one of the preceding claims, comprising a gripping element (16) placed at the top of the bearing frame (2), which can be positioned above the central portion of the stiffening element (7).11 . Patient-specific navigation guide kit comprising two navigation guides (1 ) according to any one of claims 1 to 10, characterised in that the two navigation guides (1 ) each have a respective bearing arm (3’) connected to a respective main guide sleeve (5), said bearing arms (3’) being placed on opposite sides, one with respect to the other of each navigation guide.

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