Bone clamp
Patent Information
- Application Number
- EP2024701557
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-04-19
- Filing Date
- 2024-01-17
- Publication Date
- 2024-12-25
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing bone clamps are not gentle enough on the patient's bone surface and do not provide optimal contact, leading to potential trauma and slow healing.
A bone clamp design featuring a dual-arm bone fixing element with articulated clamping jaws and a spring-loaded mechanism that allows for improved contact with the bone surface, reduced trauma, and balanced clamping force, along with a secure clamping mechanism using a sleeve section and internal thread, enabling precise positioning and reduced force requirements.
The bone clamp achieves better contact with the bone surface, reduces trauma, and promotes faster healing by minimizing the amount of bone material displaced, while maintaining secure clamping force and allowing for easy attachment of a reference marker.
Smart Images
Figure EP2024051035_24102024_PF_FP_ABST
Abstract
Description
[0001] bone clamp
[0002] DESCRIPTION:
[0003] The invention relates to a bone clamp having a first lever and a second lever, which are connected to one another via a clamp joint, and having at least one bone fixing element associated with the distal end of the first lever or the second lever, which is mounted on the distal end by a fixing joint, wherein at least one clamping jaw is mounted in an articulated manner on the bone fixing element via a jaw joint.
[0004] Imaging techniques such as computed tomography (CT) using X-rays, magnetic resonance imaging (MRI), positron electron tomography (PET), and ultrasound imaging are used in medicine for diagnostic purposes and are also used to guide a surgeon during an operation and to support them during the surgical procedure by providing up-to-date information that can be provided in real time with high spatial and temporal resolution. Navigation systems are used to ensure correct spatial orientation; these can also record and evaluate patient movements during the operation. These navigation systems include a reference marker that must be positioned on the patient. This should preferably be reversible and detachable, yet still have a stable, stationary connection to avoid data offset.In addition to bone anchors, which are inserted invasively into the bone, bone clamps are also suitable for this purpose, although the specific application influences the choice between a bone anchor and bone clamps. Bone clamps are used in particular in spinal surgery because sufficiently large and stable bones are available. EP 3 247 297 B1 discloses a bone clamp for attachment to a bone, which consists of a first lever and a second lever that are connected to one another in an articulated manner. The position of one lever can be determined relative to the other lever by adjusting a sliding block mounted on one lever relative to one lever by means of a screw that is rotatably and immovably mounted in the sliding block, so that it rests against a sliding surface on the other lever.US 2009 / 0062869 A1 discloses a bone clamp in which a pivoting lever is pivotally mounted on a rigid rod, wherein clamping plate supports are mounted on the free ends of the pivoting lever and the rod, which carry clamping plates.
[0005] It is the object of the present invention to provide a bone clamp that enables improved contact with the bone surface and is gentler for the patient.
[0006] This object is achieved by a bone clamp having the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.
[0007] The bone clamp of the type mentioned above is characterized by the fact that the interaction of the jaw joint and the fixation joint allows the clamping jaw to more easily adhere to the surface of the bone. This is particularly promoted when the bone fixation element is formed from a first arm and a second arm, there are two clamping jaws, and one of the clamping jaws is articulated on each arm via the jaw joint. The clamping jaws are individually pivotable, so that, including the fixation joint and the two jaw joints, three pivot axes are available. This allows the clamping jaws to function like a kinematic multi-body chain and further improve contact with the outer contour of the bone. In this context, it is advantageous, also for reasons of symmetry, if the fixation joint is arranged between the two arms.
[0008] It is further preferred if a groove delimited by two groove webs is formed in the free end of the arm, into which the clamping jaw is inserted, wherein bearing receptacles are formed in the two groove webs, into which a joint bolt carrying the clamping jaw is inserted in order to form the jaw joint in a simple manner.
[0009] The clamping jaw is expediently formed from a bolt carrier having a through-opening and a clamping plate arranged on the bolt carrier, since in this way the functions of the clamping jaw can be separated and assigned to separate components.
[0010] In a preferred embodiment, the fixation joint in the bone fixation element is formed by a joint passage accommodating a joint axis, which is traversed by a spring passage into which a spring is inserted, which is supported on the two clamping jaws assigned to the arms. This spring ensures that the two clamping jaws in the bone fixation element are held in a neutral position, which is advantageous when the bone clamp is initially only brought into contact with the bone through a tissue opening. This neutral position is maintained until contact with the bone is achieved, whereby an at least partial compensation of the clamping force between the clamping jaws can be achieved.
[0011] To improve the grip of the clamping jaw on the bone surface, at least one pin is arranged on the clamping plate, preferably multiple pins. The pin is formed from two intersecting cutting edges that converge arrow-like into a point at the free end. This design reduces the forces required to perforate the bone, as only a small amount of bone material needs to be displaced. Another positive aspect is that the trauma is less than with, for example, a pyramidal shape of the pins, so that the bone can heal more quickly after the bone clamp is removed. In principle, it is conceivable to assign the fixation element to only one of the levers and to secure the other lever to the bone using friction or a differently designed clamping device.However, it is particularly preferred if the fixing element according to the invention is present twice and if one of the fixing elements is assigned to the distal end of both the first lever and the second lever.
[0012] It is further particularly preferred if a sleeve section is formed on the proximal region of the first lever, on the inside of which sleeve section an internal thread is formed, into which a clamping element having an external thread can be screwed so that its free end rests against the proximal region of the second lever. This simple construction, which does not require a sliding block, allows the position of the two levers to be secured in a clamped position. The clamping force achieved is thereby permanently maintained. It should also be noted that the design of this securing mechanism in the proximal region can be implemented independently of the measures at the distal end of the two levers, even if the advantages of securing the clamping force are particularly evident when using the bone fixation elements according to the invention with the clamping jaws.
[0013] It is also advantageous to have a biasing spring acting between the first and second levers, which urges the first and second levers toward closing their distal ends. This spring ensures that both levers remain in a closed configuration, which offers advantages when inserting the sleeve clamp into the patient.
[0014] Good contact between the clamping element and the proximal region of the second lever, regardless of its position, is achieved when the free, distal end of the clamping element is free of threads and rounded. A reference marker can be coupled to the bone clamp as intended. For this purpose, a clamping surface is expediently formed on the outside of the sleeve section, to which the reference marker is attached. The sleeve section thus has a dual function, which in turn promotes the simple construction of the bone clamp. The assembly of the reference marker can be simplified by forming an annular collar at the distal end of the sleeve section.
[0015] The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figure, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also considered to be encompassed and disclosed by the invention that are not explicitly shown or explained in the figure, but which emerge and can be produced through separate feature combinations from the explained embodiments.
[0016] Further advantages, features, and details of the invention will become apparent from the claims, the following description of preferred embodiments, and the drawings. Herein:
[0017] Figure 1 is a side view of a bone clamp shown in the configuration suitable for insertion,
[0018] Figure 2 is a perspective view of the bone clamp of Figure 1 in the configuration suitable for gripping a bone section,
[0019] Figure 3 shows a representation of the bone clamp corresponding to Figure 2, in the configuration determined for clamping by a clamping element,
[0020] Figure 4 is a perspective view of the bone clamp of Figure 3, carrying a reference marker,
[0021] Figure 5 is an exploded view of the clamping section of the bone clamp with the bone fixation elements,
[0022] Figure 6 shows detail VI from Figure 5,
[0023] Figure 7 is an exploded view of the bone fixation element from Figure 6,
[0024] Figure 8 shows a representation of a bone fixing element corresponding to Figure 6 in a first pivoting position of the clamping jaws,
[0025] Figure 9 shows a representation of a bone fixing element corresponding to Figure 6 in a further pivoting position of the clamping jaws,
[0026] Fig. 10 shows a representation of a bone fixing element corresponding to Figure 6 in a further pivoting position of the clamping jaws,
[0027] Fig. 1 1 an isolated, perspective view of a clamping jaw,
[0028] Fig. 12 is a plan view of the clamping jaw of Figure 11,
[0029] Fig. 13 a perspective view of the bone clamp attached to a cervical spine, carrying a reference marker,
[0030] Fig. 14 the detail XIV from Figure 13,
[0031] Fig. 15 is a perspective view of the bone clamp attached to a lumbar spine, carrying a reference marker, and
[0032] Fig. 16 the detail XVI from Figure 15. Fig. 17 a perspective view of the bone clamp from Figure 1, with screwed-in clamping element, in the closed configuration,
[0033] Fig. 18 is a view corresponding to Figure 17, without clamping element, in the open configuration, and
[0034] Fig 19 is an exploded view of the bone clamp from Figure 18.
[0035] Figure 1 shows a bone clamp 1 in a closed configuration, as it exists at the beginning of a placement of the bone clamp 1 through a tissue opening in a patient. The bone clamp 1 is formed by a first lever 2 and a second lever 3, which are connected to one another via a clamp joint 4. The levers 2, 3 are rounded and, in the area intended for insertion into the patient, complement one another in cross-section to form an almost circular shape. Along the main axis of the first lever 2 and the second lever 3, a cylindrical outer surface is approximated at least in sections, wherein when the distal clamping area is opened by pressing the two proximal lever ends together, the inner side of the second lever 3 projects into the cylindrical inner opening of the first lever 2 (Figure 18). The sleeve section of the first lever 2 projects beyond the length of the second lever 3 in the proximal direction (Figure 1).
[0036] A biasing spring 5 is arranged between the first lever 2 and the second lever 3, which urges the first lever 2 and the second lever 3 toward closing the distal ends. In the embodiment shown, the biasing spring 5 is assigned to the proximal region of the two levers 2, 3 and is designed as a compression spring.
[0037] At the proximal region of the first lever 2, there is a sleeve portion 6, on the inside of which an internal thread 7 is formed, into which a clamping element 8 having an external thread 9 can be screwed. The clamping element 8 can be screwed into the sleeve portion 6 so that its free end rests against the proximal region of the second lever 3. The free, distal end of the clamping element 8 is free of threads and rounded.
[0038] This design holds the bone clamp 1 in the closed configuration shown in Figure 1, which is particularly suitable for inserting the bone clamp 1 into patients because the tissue is protected. Once the bone clamp 1 is close to the bone, the two levers 2, 3 can be adjusted against the force of the preload spring 5 (Figure 2). The desired configuration can be secured by the clamping element 8 and the required clamping force can be applied (Figure 3).
[0039] Once this is achieved, a reference marker 10 can be coupled to the bone clamp 1, as shown in Figure 4. For this purpose, a clamping surface 11 is formed on the outside of the sleeve section 6, to which the reference marker 10 is attached. The sleeve section 6 can also have an annular collar 12 as a stop in order to clearly define the position of the reference marker 10 relative to the bone clamp 1.
[0040] It is particularly important that a reference marker 10 fixed relative to the bone permanently maintains its position, regardless of whether the contour of the bone surface is rounded or rather flat, as can be described with regard to the spinous process 13 of the vertebrae in a spinal column 14 (Figures 13 to 16).
[0041] For this purpose, the bone clamp 1 has at least one bone fixation element 15 assigned to the distal end of the first lever 2 or the second lever 3. In the embodiment shown, the bone fixation element 15 is present twice, with one of the bone fixation elements 15 being assigned to the distal end of both the first lever 2 and the second lever 3. The distal end of the levers 2, 3 has a slightly larger outer diameter than the proximally adjacent section (Figure 1). The bone fixation element 15 is mounted on the distal end by a fixation joint 16 (Figure 5), with at least one clamping jaw 17 being articulated on the bone fixation element 15 via a jaw joint 18.In the embodiment shown, the bone fixing element 15 is formed from a first arm 19 and a second arm 20, so that the clamping jaw 17 is present twice and one of the clamping jaws 17 is articulated on each of the arms 19, 20 via the jaw joint 18 (Figure 7).
[0042] Figure 7 shows in detail the structure of one of the bone fixation elements 15. The fixation joint 16 is arranged between the two arms 19, 20 and in the free end of each arm 19, 20 a groove 22 is defined by two groove webs 21, into which the clamping jaw 17 is inserted. Figure 7 also shows that bearing receptacles 23 are formed in the two groove webs 21, into which a hinge pin 24 carrying the clamping jaw 17 is inserted. At the distal end of the first lever 2 and the second lever 3, a surface section is arranged such that a stop surface 34 is provided for the bone fixation element 15, specifically on the groove webs 21, wherein the clamping plate 27 is wider than the groove 22. The stop surface can be angled (Figure 19) to allow for greater deflection.
[0043] The clamping jaw 17 itself is formed from a bolt carrier 26 having a through-opening 25 and a clamping plate 27 arranged on the bolt carrier 26.
[0044] In the bone fixation element 15, the fixation joint 16 is formed by a joint passage 29 receiving a joint axis 28, which is crossed by a spring passage 30 into which a spring 31 is inserted, which is supported on the two clamping jaws 17 assigned to the arms 19, 20, namely the bolt carriers 26. This spring 31 aligns the clamping jaws 17 in a rest position shown in Figure 9, from which the clamping jaws 17 can be deflected (Figures 8 and 10) in order to adapt to the contour of the bone surface. If the contact of the clamping jaws 17 with the bone surface is lost again, the clamping jaws 17 return to the rest position due to the action of the spring 31.
[0045] Furthermore, at least one mandrel 32 is arranged on the clamping plate 27, of which there are multiple ones in the embodiment shown. The mandrel 32 itself is formed from two intersecting cutting edges 33 which converge towards a point like an arrow at the free end. This design means that only low forces are required to perforate the bone because only a small amount of bone material needs to be displaced, which also promotes healing because only small areas are affected. In addition, the shape prevents the bony structure (spinous process) from being accidentally "pinched off". The vertical extent of the arrow-shaped cutting edges 33 is relatively large. This promotes stabilization against the bone. The number of cutting edges 33 is not necessarily limited to two; for example, there could also be three blades at an angle of 120°.
[0046] The following briefly describes the use of the bone clamp 1 according to the invention. An access to the bone to which the bone clamp 1 is to be attached is created in the patient. Starting from the configuration shown in Figure 1, the bone clamp 1 is inserted toward the bone, protecting the patient's tissue from the aggressive spikes 32 of the bone fixation element 15. The configuration shown in Figure 1 is determined by the preload spring 5 and the spring 31.
[0047] Once the bone clamp 1 is close to the bone, the proximal ends of the levers 2, 3 can be pivoted toward each other to open the distal ends. The pivoting can be done manually or by screwing the clamping element 8 into the sleeve section 6 until the desired opening angle is reached. In this configuration, the bone fixation elements 15 can adapt to the bone contour by pivoting the clamping jaws 17 via the jaw joints 18, and the bone fixation element 15 aligns itself via the fixation joint 16. Once this has been achieved, the clamping force is increased by further twisting the clamping element 8 in the sleeve section 6.
[0048] The reference marker 10 can then be fastened to the outer clamping surface 11 of the sleeve section 6 using a clamping ring.
[0049] After the end of use, the reference marker 10 and the bone clamp 1 are removed in the reverse order, whereby after the mandrels 32 are removed from the bone, rapid wound healing is promoted due to the low trauma.
[0050] LIST OF REFERENCE SYMBOLS:
[0051] Bone clamp first lever second lever clamping joint preload spring sleeve section
[0052] Internal thread clamping element external thread reference marker clamping surface collar pedicle
[0053] spine
[0054] Bone fixation element Fixation joint Clamping jaw Jaw joint First arm Second arm Groove web Groove
[0055] Bearing holder, hinge pin, through hole, bolt carrier, clamping plate
[0056] Joint axis Joint passage Spring passage Spring
[0057] mandrel
[0058] Cutting edge 34 stop surface
Claims
CLAIMS:
1. Bone clamp (1) with a first lever (2) and a second lever (3), which are connected to one another via a clamp joint (4), and with at least one bone fixing element (15) assigned to the distal end of the first lever (2) or the second lever (3), which is mounted on the distal end by a fixing joint (16), characterized in that at least one clamping jaw (17) is mounted in an articulated manner on the bone fixing element (15) via a jaw joint (18).
2. Bone clamp (1) according to claim 1, characterized in that the bone fixing element (15) is formed from a first arm (19) and a second arm (20), that the clamping jaw (17) is present in duplicate and that one of the clamping jaws (17) is articulated on each of the arms (19, 20) via the jaw joint (18).
3. Bone clamp (1) according to claim 2, characterized in that the fixing joint (16) is arranged between the two arms (19, 20).
4. Bone clamp (1) according to claim 2 or 3, characterized in that in the free end of the arm (19, 20) there is formed a groove (22) delimited by two groove webs (21) into which the clamping jaw (17) is inserted.
5. Bone clamp (1) according to claim 4, characterized in that bearing receptacles (23) are formed in the two groove webs (21), into which a hinge pin (24) carrying the clamping jaw (17) is inserted.
6. Bone clamp (1) according to one of claims 1 to 5, characterized in that the clamping jaw (17) is formed from a bolt carrier (26) having a through-opening and a clamping plate (27) arranged on the bolt carrier (26).
7. Bone clamp (1) according to one of claims 1 to 6, characterized in that at least one surface section is arranged at the distal end of the first lever (2) and / or the second lever (3) in such a way that a stop surface (34) is provided for the associated bone fixing element (15).
8. Bone clamp (1) according to one of claims 4 to 7, characterized in that the clamping plate (27) is wider than the groove (22) delimited by two groove webs (21).
9. Bone clamp (1) according to claim 7 or 8, characterized in that the groove webs (21) have two surface sections which serve as stop surfaces (34) for the clamping plate (27).
10. Bone clamp (1) according to one of claims 6 to 9, characterized in that in the bone fixing element (15) the fixing joint (16) is formed by a joint passage (29) receiving a joint axis (28) which is crossed by a spring passage (30) into which a spring (31) is inserted, which is supported on the two clamping jaws (17) assigned to the arms (19, 20). 1 1. Bone clamp (1) according to claim 6 to 9, characterized in that at least one mandrel (32) is arranged on the clamping plate (27).
12. Bone clamp (1) according to claim 1 1, characterized in that the mandrel (32) is present in multiple quantities and that the mandrel (32) is formed from intersecting cutting edges (33) which converge in an arrow-like manner to a point at the free end.
13. Bone clamp (1) according to one of claims 1 to 12, characterized in that the bone fixing element (15) is present twice, and that one of the bone fixing elements (15) is assigned to the distal end of both the first lever (2) and the second lever (3).
14. Bone clamp (1) according to one of claims 1 to 13, characterized in that a sleeve section (6) is formed on the proximal region of the first lever (2), on the inside of which an internal thread (7) is formed, into which a clamping element (8) having an external thread (9) can be screwed for abutment with its free end on the proximal region of the second lever (3).
15. Bone clamp (1) according to claim 14, characterized in that the free, distal end of the clamping element (8) is free of threads and is rounded or conical.
16. Bone clamp (1) according to one of claims 1 to 15, characterized in that a reference marker (10) is coupled.
17. Bone clamp (1) according to claim 16, characterized in that a clamping surface (11) is formed on the outside of the sleeve portion (6), on which the reference marker (10) is fastened.
18. Bone clamp (1) according to one of claims 1 to 17, characterized in that a pretensioning spring (5) acting between the first lever (2) and the second lever (3) is present, which biases the first lever (2) and the second lever (3) in the direction of closing the distal ends.
19. Bone clamp (1) according to one of claims 15 to 18, characterized in that a cylindrical outer surface is approximated at least in sections along the main axis of the first and second lever (2, 3).
20. Bone clamp (1) according to one of claims 14 to 19, characterized in that when the distal clamp region is opened by pressing the two proximal lever ends together, the inside of the second lever (3) projects into the cylindrical inner opening of the first lever (2).
21. Bone clamp (1) according to one of claims 14 to 20, characterized in that, in its open state, a clamping element (8) is mounted within the proximal sleeve portion (6) of the first lever (2), and by axial displacement of the clamping element (8) in the distal direction, the second lever (3) above, proximal to the clamping joint (4), is forced radially outward.
22. Bone clamp (1) according to one of claims 1 to 21, characterized in that the sleeve portion (6) of the first lever (2) projects beyond the length of the second lever (3) in the proximal direction.