EP4719259A1 - Orientation aid for orienting a bone section - Google Patents

Abstract

An orientation aid (1) for orienting a bone section (10) of a bone (11), for example, in a osteotomy tilting surgery, wherein it includes a first orientation reference (31) defining a first 3D axis system (X, Y, Z), and a second orientation reference (32) defining a second 3D axis system (X', Y', Z') rotated through at least a rotation angle (α, β, γ) in relation to the first 3D axis system (X, Y, Z), wherein the at least one rotation angle (α, β, γ) corresponds to a predetermined rotation angle (α, β, γ) of the bone section (10) in relation to a reference section (17) of the bone (11) which is different from this bone section (10).

Description

ORIENTATION AID FOR ORIENTING A BONE SECTION

The invention relates to an orientation aid for orienting a section of a bone during, for example, an osteotomy tilting surgery. The bone may be part of a joint. Further, the invention also relates to a computer-implemented method for designing and manufacturing such an orientation aid.

An example of a bone or joint to which the invention may be applied is the hip joint, which is a ball and socket joint in which a hip head of the femur moves in a hip socket of the hip bone. Patients who suffer, for example, from hip dysplasia struggle with inadequate or improper coverage of the hip head by the hip socket. This may be caused by, for example, a malformed hip socket.

These patients may possibly be treated by means of a surgical procedure called a peri-acetabular osteotomy, also called a triple pelvic osteotomy, Ganz osteotomy or Bernese osteotomy (hereinafter referred to as PAO surgery). In this type of surgery, all or part of the hip socket, also called the acetabulum, is separated from the surrounding bone of the pelvis. The surrounding pubis, ischium and/or ilium are sawn through for this purpose by means of osteotomes or oscillating saw blades. The bone section containing the acetabulum can then be reoriented in relation to the surrounding pelvis.

This surgical procedure is performed to improve the coverage, or also cover-over, of the hip socket over the femur's femoral head in the hip joint. After reorientation of the hip socket in the hip bone, the bone section containing this hip socket is fixed with screws and/or plates to secure the hip socket in its new position in the hip bone. After healing and rehabilitation, the hip socket should cover the femoral head better, improving the alignment and stability of the hip joint. This reduces pressure on the articular cartilage, pain and limping, and can prevent (sub)luxation of the joint.

The main disadvantage of this peri-acetabular osteotomy (PAO), besides a long rehabilitation for the patient, is that the surgical procedure is difficult to plan in advance and, when performed, accurate and optimal orientation of the hip socket is difficult to ensure. The outcome of the surgical procedure depends mainly on the experience and feeling of the surgeon. Under- or overcompensation of the coverage of the hip socket over the femoral head is common, leading to complications, such as, for example, limitation in the mobility of the hip joint due to impingement of the femoral head, and/or partial dislocation at the front of the hip socket. This ultimately leads to a non-optimal outcome for the patient, possibly resulting in more surgery and/or premature placement of a total hip prosthesis.

A computer-assisted planning of a PAO and intra-operative navigation during the PAO using an orientation reference fastened to the bone is described by Liu et al. in "Computer Assisted Planning, Simulation and Navigation of Periacetabular Osteotomy," Aug. 14, 2016. SAT 2015 18th International Conference, Austin, TX, USA, September 24-27, 2015; [Lecture Notes in Computer Science; Leet. Notes Computer], Springer, Berlin, Heidelberg, page(s) 15-26. However, the used navigation and tracking system is quite complex.

The invention aims to propose a device and method to remedy these disadvantages. In particular, the invention aims to remedy these disadvantages by proposing an orientation aid and method making it possible to plan the surgical procedure with the optimal desired orientation of a bone section to be reoriented, thereby designing and manufacturing the orientation aid so that it provides a simple way to accurately perform the planned surgical procedure with the planned orientation of the bone section.

To this end, the orientation aid comprises, as also claimed in the appended claims:

- a first orientation reference defining a first 3D axis system and a second orientation reference defining a second 3D axis system rotated about at least one rotation angle in relation to the first 3D axis system, wherein the at least one rotation angle corresponds to a predetermined rotation angle of the bone section in relation to a reference section of the bone different from said bone section;

- a fastener to fasten the orientation aid at least partially to the bone section, with at least the second orientation reference to the bone section. The 3D axis systems are preferably orthogonal axis systems. However, they may also be oblique axis systems in which one or more axes are at an angle to each other that is different from 90°. Further, aligning the 3D axis system preferably includes positioning the axes of this axis system parallel to a reference line, a reference plane and/or the corresponding axes of a reference axis system or another 3D axis system.

Practically, the orientation aid has at least one lockable rotation point around which the first orientation reference including the first 3D axis system and the second orientation reference including the second 3D axis system can rotate together in relation to the fastener. Preferably, this rotation point is located between the fastener and the orientation references.

Advantageously, the first orientation reference is provided to be aligned with the first 3D axis system with respect to a reference.

The second orientation reference may be provided to be aligned with the second 3D axis system with respect to the reference.

The reference preferably defines at least a basic 3D reference axis system (X°, Y°, Z°) and/or an external 3D reference axis system.

The reference may include at least a horizontal plane and/or a straight line.

In a particular manner, the orientation aid is provided with an additional reference aid, wherein said reference aid comprises a third orientation reference defining a third 3D axis system and is provided to align this third orientation reference including the third 3D axis system with the first 3D axis system and/or with the reference, and further includes a reference fastener to fasten the reference aid with the third orientation reference and the third 3D axis system to the reference section of the bone.

Preferably, the second orientation reference is provided to be aligned with the second 3D axis system in relation to the third 3D axis system.

In particular, the first, the second and/or the third orientation reference include at least a spirit level and/or visualizable reference points that at least partially define the 3D axis systems. Thus, the first and second orientation references may each include at least two visualizable reference points, preferably at least three visualizable reference points each that are not in line, in particular at least four visualizable reference points each that are not situated in a plane.

In a very advantageous manner, the second orientation reference is provided to be aligned with the second 3D axis system with respect to the first 3D axis system, preferably together with the fastener.

In an interesting manner, the second orientation reference including the second 3D axis system is rotatable and lockable with respect to the first orientation reference including the first 3D axis system.

In a further interesting manner, the second orientation reference including the second 3D axis system is detachable from the first orientation reference including the first 3D axis system. Thus, the first and second orientation references can be detached from each other.

In a very interesting manner, the fastener comprises a first fastener for fastening the first orientation reference including the first 3D axis system to the bone's reference section and a second fastener to fasten the second orientation reference including the second 3D axis system to the bone section to be reoriented.

In an efficient manner, the second orientation reference including the second 3D axis system is fixed to the first orientation reference including the first 3D axis system and, preferably, it is made in one piece.

Thus, the invention also further relates to a computer- implemented method for designing and manufacturing the orientation aid, as is also claimed in the appended claims, which includes:

- generating a 3D model of at least a section of the bone and/or joint, for example, based on medical imaging techniques;

- defining a basic 3D axis system for the reference section of the bone;

- virtually positioning the bone section from an original position into a desired position by rotating this bone section in relation to the reference section about the at least one rotation angle and determining this rotation angle in the basic 3D axis system;

- integrating, in this orientation aid, the first 3D axis system in the first orientation reference and the second 3D axis system in the second orientation reference rotated about the at least one rotation angle with respect to the first 3D axis system;

- providing the fastener in this orientation aid to fasten the orientation aid at least partially to the bone section, preferably with at least the second orientation reference to the bone section.

The orientation aid according to the invention may further be used in the surgical treatment of hip dysplasia.

The orientation aid is preferably designed and manufactured in such a manner that the desired position of the bone section containing a hip socket is determined by improving the coverage of a femur's hip head by the hip socket without any undesirable obstruction, impingement and/or interference between the femur and the bone section with the hip socket in the desired position.

Other particularities and advantages of the invention will become apparent from the following description of some specific embodiments of the device and method according to the invention. This description is given by way of example only and does not limit the scope of the claimed protection in any way; the reference numerals used hereinafter refer to the figures added thereto.

Figure 1 is a schematic view in perspective of a right hip joint.

Figure 2 is a schematic representation of a right hip joint diagram showing the radial overlay of the femoral head by the hip socket for analysis of this coverage.

Figure 3 is a schematic view in perspective of a hip bone of the right hip joint in which a bone section containing the hip socket is rotated with respect to the surrounding hip bone.

Figure 4 is a schematic view in perspective of an orientation aid according to a first embodiment of the invention. Figure 5 is a schematic view in perspective of an orientation aid as shown in Figure 4, fastened to a bone section containing the hip socket of a hip bone, wherein the first orientation reference including the first 3D axis system is aligned in relation to the reference.

Figure 6 is a schematic view in perspective, as in Figure 5, wherein the bone section is rotated with respect to the surrounding hip bone, with the second orientation reference including the second 3D axis system being aligned in relation to the reference.

Figure 7 is a schematic view in perspective of an orientation aid according to a second embodiment of the invention.

Figure 8 is a schematic view in perspective of an orientation aid according to a fifth embodiment of the invention.

Figure 9 is a schematic view in perspective, as in Figure 8, wherein the second orientation reference including the second 3D axis system is aligned in relation to the first orientation reference including the first 3D axis system.

Figure 10 is a schematic view in perspective of an additional reference aid according to a sixth embodiment of the invention.

In the different figures, the same reference numerals refer to the same or analogous elements.

The invention generally relates to a method for designing and manufacturing an orientation aid during the planning of a surgical procedure in which a bone section is reoriented into a desired position. To this end, said bone section may need to be at least partially detached from the surrounding bone and rotated in relation to its original position. While planning, the desired position of the bone section is virtually determined. In the process, the rotation angles through which the bone section must be rotated from its original pre-surgical position into the desired position are determined. The orientation aid allows for a simple transposition of these rotation angles during the surgical procedure to thus reorient the bone section into the desired predetermined position or also the planned position. In particular, the invention relates to a method for planning a peri-acetabular osteotomy (PAO) prior to performing the surgical procedure. An orientation aid is thereby designed and manufactured that allows the planned reorientation of a bone section with the hip socket (acetabulum) to be reliably and accurately performed during the surgical procedure.

The invention is described below in more detail with respect to PAO but, of course, it can also be applied analogously to other rotational osteotomies, for example, osteotomy of the bone at the jaw, knee or shoulder. At the knee, for example, it can be applied at the level of the upper leg (femur) and/or shin bone (tibia), for example to correct bowlegs or knock-knees.

According to a first embodiment of the method, a digital 3D model is made of the bone 11, in particular the pelvis with the hip joint, or at least of a part of the femur 23 with the hip head 22 and a part of the hip bone 24 with the hip socket 19, as is shown, for example, in Figure 1 for the right hip joint. The 3D model can be based on data obtained by inherently known medical imaging techniques such as, for example, an X-ray scan, a CT scan, and/or an MRI scan. Based on this imaging, the coverage of the hip head 22 by the hip socket 19 can be determined and analysed.

The PAO surgery aims to optimize the coverage of the hip head 22 by rotating the hip socket 19, or also the bone section 10 containing the hip socket 19, after it has been at least partially detached from the surrounding hip bone 24, or also the surrounding bone 11, into a new position in relation to the original pre-surgical position. Thus, for example, an attempt can be made to increase the lateral and anterior coverage of the hip socket 22 in relation to the situation in the pre-surgical position. The optimal orientation of the hip socket 19 in relation to the pre-surgical position depends on several factors and can be determined by the orthopaedic surgeon. Factors that may play a role include, for example, improved lateral and anterior coverage of the femoral head 22 without any undesirable obstruction, the mobility (flexion/extension, abduction/adduction, internal and external rotation) of the femur 23 in relation to the hip bone 24 without any interference between the femur 23 and the reoriented bone section 10 with the hip socket 19.

The analysis can be based at least partly on a comparison of the coverage of the hip head 22 in the patient compared to that in an average population. Schematically, this can be represented in a diagram as shown in Figure 2 for a right hip joint, for example. In this bell diagram, the radial coverage, measured in relation to the vertical direction or also the coverage of the hip head 22 by the hip socket 19 is shown in different directions, in particular laterally 34, medially 35, anteriorly 37 and posteriorly 36. In the lateral direction, the value of the curve corresponds to the known 'Lateral Centre Edge' (LCE) angle, which is classically derived from an X-ray image increased by 90 degrees.

Line 21 represents the coverage of a patient suffering from hip dysplasia. Line 38 shows the coverage for the same patient where the bone section 10 with the hip socket 19 is virtually reoriented. By each time performing a kinematic analysis based on a virtually reoriented position to check the range-of- motion of the femur 23, it can be avoided that a virtually reoriented position would lead to unwanted interference (impingement) with the femur 23 or the attached muscles and/or tendons. In this way, distinct positions of the hip socket 19 can be compared and analysed, for example, with respect to their more optimal overlay of the femoral head 22 and the resulting kinematic range of motion, in order to derive an optimal position. Thus, it is possible for the practitioner to determine an optimal position of the hip socket 19.

The reorientation of the bone section 10 containing the hip socket 19 with respect to its pre-surgical position can be defined by the rotation about one to three axes of a preferably orthogonal 3D axis system (X°, Y°, Z°), as shown in Figure 3, possibly neglecting any translation. Thus, it may be assumed that the hip socket 19 is rotated about a pivotal point 25 of the hip head 22. Thus, for example, an angle of rotation a, |3 and/or y can be determined about each of the axes X°, Y° and/or Z°, respectively, in the 3D axis system (X°, Y°, Z°) having its origin 26 in this pivotal point 25. To surgically perform the planned reorientation of the hip socket 19, according to this first embodiment, an orientation aid 1 is manufactured that can transpose at least one of the planned rotation angles a, |3 and/or y, and that can preferably transpose all planned rotation angles a, p and y, as shown in Figures 4, 5 and 6.

Thus, a first, preferably orthogonal, 3D axis system (X, Y, Z) and a second, preferably orthogonal, 3D axis system (X', Y', Z') is integrated in the orientation aid 1 via a first orientation reference 31 and a second orientation reference 32, respectively. Here, the second 3D axis system (X', Y', Z') is rotated in relation to the first 3D axis system (X, Y, Z) about the planned rotation angles a, |3 and/or y. Thus, the 3D axis systems represent 3D coordinate systems here. Obviously, all spatial coordinates known as such can be used in this case such as, for example, cartesian coordinates, polar coordinates or spherical coordinates, cylinder coordinates and/or vector coordinates.

Furthermore, the orientation aid 1 is provided with one or more fasteners 2 for fastening the orientation aid 1 to the bone section 10 of the hip bone 24, in the vicinity of the hip socket 19. Suitable fasteners 2 for the bone are known as such and may include, for example, Steinmann or Schanz pins, screws, and/or Kirschner wires (K-wires).

Preferably, the orientation aid 1 has a distal end provided with the one or more fasteners 2 and a proximal end provided with the first and the second orientation references 31 and 32.

According to the first embodiment, the first orientation reference 31 for the first 3D axis system (X, Y, Z) comprises two transverse levels 12 and 13 and two reference points 8 and 9.

The levels 12 and 13 define a plane that is horizontal when both levels are horizontal, as in the case of orientation reference 31 in Figure 5. The plane defined by the levels 12 and 13 is preferably parallel to the plane defined by the X and Y axes of the first 3D axis system (X, Y, Z). The reference points 8 and 9 are fixed with respect to the levels 12 and 13 and define a line that is not transverse to the plane defined by the levels 12 and 13 but is preferably parallel thereto.

The levels 12 and 13 visualise a rotation about the X° axis and the Y° axis, respectively, of a 3D reference axis system (X°, Y°, Z°) of a reference 14. The two reference points 8 and 9 visualise a rotation about the Z° axis of the 3D reference axis system (X°, Y°, Z°).

Furthermore, the orientation reference 32 for the second 3D axis system (X', Y', Z') also contains, in an analogous manner, two transverse levels 12' and 13' and two points 8' and 9'. Here, these levels 12' and 13' and the points 8' and 9' of the orientation reference 32 are rotated about the axes X, Y and Z of the first 3D axis system (X, Y, Z), through the planned rotation angles a, |3 and y, respectively.

Preferably, the first 3D axis system (X, Y, Z) and the second 3D axis system (X', Y', Z') and therefore also the spirit levels 12, 13, 12' and 13' and the reference points 8, 9, 8' and 9' are fixed, or at least can be fixed, with respect to each other. The levels 12, 13, 12' and 13' may be analogue and/or digital. They could possibly also be laser spirit levels projecting reference lines onto external visualisation planes.

The reference points 8, 9, 8' and 9' may possibly be visualised by, for example, fluoroscopy, X-rays or other medical imaging that can, preferably, provide an anterior-posterior image of the pelvis and orientation aid. These reference points may also be replaced by and/or supplemented with, for example, a laser beam and/or a laser spirit level projecting a vertical reference line. The spirit levels placed transversely in this first embodiment may form a cross level and/or may be replaced by a circular vial spirit level.

Furthermore, the orientation aid 1 also includes a lockable rotation point 4 between the fastener 2, on the one hand, and the first and second orientation references 31 and 32, on the other hand, and, consequently, also the first 3D axis system (X, Y, Z) and the second 3D axis system (X', Y', Z'). Thus, the first and second orientation references 31 and 32 may rotate together about the rotation point 4 in relation to the fastener 2 and, for example, be fixed in a particular orientation in relation to the hip bone 24.

Preferably, the first and second orientation references 31 and 32 are provided as a fixed assembly in the orientation aid 1. This may be manufactured by means of an additive manufacturing technique known as such.

Optionally, the orientation aid could also be provided so that the first and second orientation references 31 and 32 can be rotated and locked with respect to each other, so that the rotation angle a, |3 and/or y between the first and second 3D axis systems can be adjusted and set, for example, in accordance with a planned acetabular reorientation for a specific patient.

The PAO surgical procedure using the orientation aid 1 according to the first embodiment can be divided into essentially four steps. It is understood that such a surgery also involves several other steps, which, however, are not relevant to the present invention and are not described here for clarity's sake.

At the start of the surgical procedure, in a first step, the patient and the orientation aid 1 are aligned with a reference 14. The reference 14 defines, for example, a basic coordinate system or also a basic 3D reference axis system (X°, Y°, Z°). Possibly, said reference 14 defines an external coordinate system or also an external 3D reference axis system. In this first embodiment, the reference 14 comprises a horizontal plane (A, B) and a straight line corresponding to the longitudinal axis C of the patient's body when it lies in or on the horizontal plane (A, B). The orientation aid 1 is fastened to the bone section 10 of the hip bone 11 in the vicinity of the hip socket 19 by means of the fastener 2. Using the orientation reference 31, the orientation aid 1 is aligned with the first 3D axis system (X, Y, Z) with respect to the reference 14. Thus, the orientation reference 31 can be rotated with the first 3D axis system (X, Y, Z) about the rotation point 4 between the fastener 2 and the first 3D axis system (X, Y, Z). In this way, the axes X, Y, Z are oriented parallel to the reference axis system (X°, Y°, Z°) with which the patient and the hip bone 24 are aligned. Thus, the spirit levels 12 and 13 are aligned with the horizontal plane (A, B) and the reference points 8 and 9 are aligned with the longitudinal axis C located in the sagittal plane, as shown in Figure 5. Consequently, the line determined by the reference points 8 and 9 is directed towards the skull and aligned parallel to the patient's spine.

When aligning the first 3D axis system (X, Y, Z), the second orientation reference 32 is also moved through the rotation point 4 together with the first orientation reference 31.

Then, the rotation point 4 is locked in a fixed position so that the first 3D axis system (X, Y, Z) of the orientation aid 1 is aligned and firmly fastened to the hip bone 24.

In a second step, the bone section 10 containing the hip socket 19 is at least partially detached from the surrounding hip bone 24. To this end, use is made of means known per se, such as, for example, osteotomes and/or saw blades.

The order of the first and second steps may possibly be reversed and/or interchanged. For example, the bone section 10 might be at least partially detached from the surrounding bone 11 before fastening and aligning the orientation aid 1 with the first 3D axis system (X, Y, Z). Possibly, after that, the bone section 10 can be further detached.

In a third step, the bone section 10 is rotated into the desired predetermined and/or also the planned position. The orientation aid 1, which has been firmlyfastened to the bone section 10, is then aligned together with the bone section 10 with respect to the reference 14, which may be and/or include the reference axis system (X°, Y°, Z), by means of the second orientation reference 32 including the second 3D coordinate system (X', Y', Z'). Thus, the spirit levels 12' and 13' are aligned with the horizontal plane (A, B) and the reference points 8' and 9' are aligned with the longitudinal axis C, as shown in Figure 6. This results in a rotation of the bone section 10 containing the hip socket 19 with respect to the surrounding hip bone 24 through the planned rotation angles a, |3 and/or y. Consequently, after aligning the second orientation reference 32 with the second 3D axis system (X', Y', Z'), the bone section 10 with the hip socket 19 will be in the planned position. In a fourth step, the at least partly loose bone section 10 is again firmly fastened to the surrounding bone of the hip bone 24 with the hip socket 19 in the planned position. For this purpose, fasteners, screws and/or plates known as such can be used.

To fix the patient's hip bone 24 during surgery, and to fix the loose bone section 10 in its new position in relation to the surrounding bone of the hip bone 24 after the planned rotation through the angles a, |3 and/or y before being able to fix both together, use can be made of known external fixation mechanisms such as articulating arms that can be fixed to the operating table. To this end, additional fasteners, such as, for example, Steinmann or Schanz pins, can be fastened to the hip bone 24, and the fasteners 2 connected to the hip bone 24 as well as the loose bone section 10 can be rigidly connected to the operating table via an articulating arm. This allows a final verification of the reoriented position and prevents unwanted rotations.

During such surgery, the position of the orientation aid 1 and therefore also of the bone section 10 can be constantly checked, for example by means of fluoroscopy, more specifically dorsal-ventral and/or lateral fluoroscopy. This technique is known as such. The reference points 8, 9, 8' and 9' are also, preferably, reference points that can be visualised by fluoroscopy. Radiopaque markers that can serve as reference points herein are also known as such. Several additional reference points can be provided for this purpose.

When changing the position of the bone section 10, the orientation aid 1 will possibly also undergo a translation if it is not positioned in the centre 25 of the rotation. However, this translation does not affect the method according to the invention, as the 3D systems of axes (X, Y, Z) and (X', Y', Z') integrated in the orientation aid 1 and the fixed rotation angles a, |3 and/or y through the respective axes still correspond to the planned rotation angles a, |3 and/or y, independently of said translation.

A second embodiment of the orientation aid 1, shown in Figure 7, differs from the previous embodiment in that the first 3D axis system (X, Y, Z) and the second 3D axis system (X', Y' Z') are orthogonal axis systems, each of which is visualised by the first orientation reference 31 and the second orientation reference 32 through three reference points 5, 6 and 7, and 5', 6' and 7', respectively, which are not situated in line, and possibly a reference point in the origin 26. The first and second 3D axis systems can possibly be chosen with the same origin 26. Furthermore, the rotation point 4 and/or the origin 26 of the first 3D coordinate system (X, Y, Z) and/or the second 3D coordinate system (X', Y', Z') can also serve as additional reference points. Preferably, these reference points can be visualised by fluoroscopy. The reference points may replace the spirit levels 12, 13, 12' and 13' and the reference points 8, 9, 8' and 9' from the first embodiment. Possibly, they can also be additionally provided in the orientation aid 1 according to, for example, the first embodiment.

According to a further refined third embodiment of the orientation aid, not shown in the figures, it is provided with digital orientation references that at least partly replace and/or supplement the analogue orientation references. These may include, for example, one or several digital spirit levels, laser spirit levels, angle indicators, inclinometers, protractors, MEMS gyroscopes, gyroscopic compasses and/or digital compasses. They can potentially generate a visual, light and/or audio signal when aligned with a reference, an external coordinate system and/or an external 3D reference axis system. This is possible, for example, when they are horizontally aligned. These digital orientation references may also be able to display a numerical value of the inclination and/or the angle of rotation.

According to an even further refined fourth embodiment of the orientation aid, not shown in the figures, it is provided with digital orientation references with one or several 3D motion sensors whose 3D movement can be monitored in real-time. To this end, the orientation references include 3D motion sensors, such as, for example, one or several MEMS gyroscopes ('Micro-electro- mechanical system' gyroscopes), a signal generator and a programmable processor with, preferably, a memory. The planned rotation angles a, |3 and/or y, the first 3D axis system (X, Y, Z) and the second 3D axis system (X', Y', Z') are programmed in the orientation reference processor. It may also be possible to programme a range of these planned rotation angles within which the rotation through these angles to the new planned position of the bone section 10 is acceptable. The orientation aid can then track the movement and rotation of the bone section 10 and, using the signal generator, generate a numerical, visual and/or auditory signal indicating when the bone section 10 is in the planned position in relation to the reference 14 and/or the original pre-surgery position.

The orientation reference with the 3D motion sensor must be firmly fastened to the bone section 10. The processor and the signal generator may be at least partly provided on a separate part of the orientation aid 1 that does not need to be fastened to the bone section 10 or the surrounding bone of the bone 11.

A fifth embodiment of the orientation aid 1, shown in Figures 8 and 9, differs from the preceding embodiments in that the orientation aid 1 is provided to be firmly fastened to the bone section 10 with the second orientation reference 32 including the second 3D axis system (X', Y', Z') and to the surrounding bone of the bone 11 with the first orientation reference 31 including the first 3D axis system (X, Y, Z). For this purpose, the fastener 2 comprises a first fastener 2' to fasten the first orientation reference 31 to a reference section 17 of the surrounding bone of the bone 11 and a second fastener 2" to fasten the second orientation reference 32 to the bone section 10.

Furthermore, in this fifth embodiment, the first orientation reference 31 including the first 3D axis system (X, Y, Z) and the second orientation reference 32 including the second 3D axis system (X', Y', Z') are detachable from each other, so that the second 3D axis system (X', Y', Z') can be aligned with respect to the first one, as shown in Figure 9. Detachable in this case means that the first orientation reference 31 and the second orientation reference 32 can be disconnected from each other, allowing them to move freely in relation to each other. This can be achieved, for example, by providing a screw clamp and/or by giving the orientation references a fitting shape. The orientation aid 1 optionally allows to rotate the two axis systems together for aligning the first 3D axis system (X, Y, Z) as in the embodiments described above, on the one hand, and to subsequently align the second 3D axis system (X', Y', Z') with respect to the first 3D axis system (X, Y, Z), on the other hand.

However, aligning the first 3D axis system (X, Y, Z) is not necessary in this embodiment. It suffices to fix both orientation references with their axis systems rotated in relation to each other through the planned rotation angles a, |3 and/or y to the reference section 17 and the bone section 10, respectively. The bone section 10 can then be placed in the planned rotated position by rotating it together with the second orientation reference 32 and aligning the second 3D axis system with the first 3D axis system. Thus, in this fifth embodiment, the first orientation reference 31 including the first 3D axis system (X, Y, Z) and the second orientation reference 32 including the second 3D axis system (X', Y', Z') are rotatable and lockable in relation to each other.

Further, in a sixth embodiment of the orientation aid 1, an additional reference aid 15, shown in Figure 10, may be provided which includes a third orientation reference 33 including a third 3D axis system (X'", Y'", Z'") to align the latter with the first 3D coordinate system (X, Y, Z) and/or with the reference 14. This reference aid 15 is provided with a reference fastener 16 to be fastened to the reference section 17. When rotating the bone section 10, the second 3D axis system (X', Y', Z") can then be aligned with the third 3D axis system (X'", Y'", Z'") of the reference aid 15. This embodiment avoids, for example, unwanted rotations of the hip bone 24 affecting the reorientation of the bone section 10, as the reference aid 15 fastened to reference section 17 will move along with the hip bone 24.

A method according to the invention for orienting a bone section 10 of a bone 11 using an orientation aid 1, for example, in an osteotomy tilting surgery, such as for the treatment of hip dysplasia, includes the following steps:

- fastening the orientation aid 1 with at least the second orientation reference 32 to the bone section 10 of the bone 11 and with the first orientation reference 31 and the second orientation reference 32 rotated in relation to each other through the at least one determined rotation angle a, |3, y; - at least partially detaching the bone section 10 from the surrounding bone as well as the reference section 17 from the bone 11;

- after fastening the orientation aid 1, aligning the second orientation reference 32, as a result of which the bone section 10 is positioned from an original position into a desired position by rotation of this bone section 10 in relation to the reference section 17 through the at least one rotation angle a, , v;

- fixing the bone section 10 in the desired position.

According to a possible embodiment of this method, it further comprises the following steps:

- fastening the orientation aid 1 including the first orientation reference 31 to the bone section 10 of the bone 11, with a lockable rotation point 4 between the fastener 2 and the first orientation reference 31 and the second orientation reference 32, and with, preferably, the first orientation reference 31 and the second orientation reference 32 fixed to each other;

- after fixing the orientation aid 1 and before aligning the second orientation reference 32, aligning the first orientation reference 31 with respect to a reference 14 by rotating it through the lockable rotation point 4 and subsequently locking said rotation point 4;

- after aligning the first orientation reference 31 and after locking the rotation point 4, aligning the second orientation reference 32 in relation to the reference 14.

According to another possible embodiment of this method, it further includes the following steps:

- fastening the orientation aid 1 with the first orientation reference 31 to the reference section 17 of the bone 11, different from the bone section 10, and with the first orientation reference 31 and the second orientation reference 32 detachable from each other;

- after fastening the orientation aid 1, aligning the second orientation reference 31 with respect to the first orientation reference 31. Of course, the invention is not limited to the above-described devices and methods and the embodiments thereof represented in the accompanying figures. Thus, the various features of these embodiments and variants can be mutually combined.

Claims

1. An orientation aid (1) for orienting a bone section (10) of a bone (11), for example, in a osteotomy tilting surgery, wherein the orientation aid (1) includes a first orientation reference (31) defining a first 3D axis system (X, Y,

Z), characterised in that the orientation aid (1) includes a second orientation reference (32) defining a second 3D axis system (X', Y', Z') rotated through at least a rotation angle (a, |3, y) in relation to the first 3D axis system (X, Y, Z), wherein the at least one rotation angle (a, |3, y) corresponds to a predetermined rotation angle (a, |3, y) of the bone section (10) in relation to a reference section (17) of the bone (11) which is different from this bone section (10); wherein the orientation aid (1) includes a fastener (2) for fastening the orientation aid (1) at least partly to the bone section (10), with at least the second orientation reference (32) to the bone section (10).

2. An orientation aid (1) according to claim 1, wherein it has at least one lockable rotation point (4) about which the first orientation reference (31) including the first 3D axis systems (X, Y, Z) and the second orientation reference (32) including the second 3D axis system (X', Y', Z') can rotate together in relation to the fastener (2).

3. An orientation aid (1) according to claims 1 or 2, wherein the first and/or the second orientation reference (31, 32) comprise at least a spirit level (12, 13, 12', 13').

4. An orientation aid (1) according to any one of claims 1 to 3, wherein the first and/or the second orientation reference (31, 32) comprise visualisable reference points (5, 6, 7, 8, 9, 5', 6', 7', 8', 9') which at least partly define the 3D axis systems.

5. An orientation aid (1) according to any one of claims 1 to 4, wherein the first orientation reference (31) is provided to align it with the first 3D axis system (X, Y, Z) with respect to a reference (14) and the second orientation reference (32) is provided to align it with the second 3D axis system (X', Y', Z') in relation to said reference (14).

6. An orientation aid (1) according to claim 5, wherein the reference (14) defines at least an external and/or a basic 3D reference axis system (X°, Y°, Z°), and/or wherein the reference (14) includes at least a horizontal plane (A, B) and/or a straight line (C).

7. An orientation aid (1) according to claims 5 or 6, provided with an additional reference aid (15) wherein this reference aid (15) comprises a third orientation reference (33) defining a third 3D axis system (X”', Y'", Z"') and is provided to align this third orientation reference (33) including the third 3D axis system (X”', Y"', Z'") with the first 3D axis system (X, Y, Z) and/or with the reference (14), and further comprises a reference fastener (16) to fasten the reference aid (15) with the third orientation reference (33) and the third 3D axis system (X”', Y'", Z'") to the reference section (17).

8. An orientation aid (1) according to claim 7, wherein the second orientation reference (32) is provided to align it with the second 3D axis system (X', Y', Z') in relation to the third 3D axis system.

9. An orientation aid (1) according to claims 7 or 8, wherein the third orientation reference comprises at least a spirit level.

10. An orientation aid (1) according to any one of claims 7 to 9, wherein the third orientation reference comprises visualisable reference points defining the 3D axis systems at least partly.

11. An orientation aid (1) according to any one of claims 1 to 10, wherein the first and second orientation references (31, 32) each comprise at least two visualisable reference points (8, 9, 8', 9'), preferably each comprise at least three visualisable reference points (5, 6, 7, 5', 6', 7') which are not in line, in particular each comprise at least four visualisable reference points (5, 6, 7, 5', 6', 7', 26) which are not situated in a plane.

12. An orientation aid (1) according to any one of claims 1 to 11, wherein the second orientation reference (32) is provided to align it with the second 3D axis system (X', Y', Z') in relation to the first 3D axis system (X, Y, Z).

13. An orientation aid (1) according to any one of claims 1 to 12, wherein the second orientation reference (32) including the second 3D axis system (X', Y', Z') is rotatable and lockable in relation to the first orientation reference (31) including the first 3D axis system (X, Y, Z).

14. An orientation aid (1) according to any one of claims 1 to 13, wherein the second orientation reference (32) including the second 3D axis system (X', Y', Z') is detachable from the first orientation reference (31) including the first 3D axis system (X, Y, Z).

15. An orientation aid (1) according to any one of claims 1 to 14, wherein the fastener (2) comprises a first fastener (2') to fasten the first orientation reference (31) including the first 3D axis system (X, Y, Z) to the reference section (17) and comprises a second fastener (2") to fasten the second orientation reference (32) including the second 3D axis system (X', Y', Z') to the bone section (10).

16. An orientation aid (1) according to any one of claims 1 to 11, wherein the second orientation reference (32) including the second 3D axis system (X', Y', Z') is fixed to the first orientation reference (31) including the first 3D axis system (X, Y, Z) and is preferably made in one piece.

17. An orientation aid (1) according to any one of claims 1 to 16 for use in the surgical treatment of hip dysplasia.

18. A computer-implemented method for designing and manufacturing an orientation aid (1) according to any one of claims 1 to 17, wherein this method comprises:

- generating a 3D model of at least a part of the bone (11);

- defining a basic 3D axis system (X°, Y°, Z°) for the reference section (17) of the bone (11);

- virtually positioning the bone section (10) from an original position into a desired position by rotating this bone section (10) in relation to the reference section (17) about the at least one rotation angle (a, |3, y) and determining this rotation angle (a, |3, y) in the basic 3D axis system (X°, Y°, Z°); - integration in the orientation aid (1) of the first orientation reference (31) including the first 3D axis system (X, Y, Z) and of the second orientation reference (32) including the second 3D axis system (X', Y', Z') rotated about the at least one rotation angle (a, |3, y) in relation to the first 3D axis system (X, Y, Z);

- providing the fastener (2) in this orientation aid (1) to fasten the orientation aid (1) at least partly to the bone section (10), with at least the second orientation reference (32) to the bone section (10).

19. A method according to claim 18, wherein the orientation aid (1) is designed and manufactured to be used in the surgical treatment of hip dysplasia, wherein the desired position of the bone section (10) containing a hip socket (19) is determined by improving the coverage of the femur's (23) hip head (22) by the hip socket (19) without any undesirable obstruction, impingement and/or interference between the femur (23) and the bone section (10) with the hip socket (19) in the desired position.

20. A method for orienting the bone section (10) of a bone (11) using an orientation aid according to claim 1, for example in an osteotomy tilting surgery comprising the following steps:

- fastening the orientation aid (1) with at least the second orientation reference (32) to the bone section (10) of the bone (11) and with the first orientation reference (31) and the second orientation reference (32) being rotated in relation to each other through the at least one defined rotation angle (a, 3, v);

- at least partially detaching the bone section (10) from the surrounding bone as well as the reference section (17) from the bone (11);

- after the orientation aid (1) has been fastened, aligning the second orientation reference (32), as a result of which the bone section (10) is positioned from an original position into a desired position by rotating this bone section (10) in relation to the reference section (17) through the at least one rotation angle (a, 3, y);

- fixing the bone section (10) in the desired position.

21. A method according to claim 20, further comprising the following steps:

- fastening the orientation aid (1), also with the first orientation reference (31), to the bone section (10) of the bone (11), with a lockable rotation point (4) between the fastener (2) and the first orientation reference (31) and the second orientation reference (32), and, preferably, with the first orientation reference (31) and the second orientation reference (32) fixed to each other;

- after fastening the orientation aid (1) and before aligning the second orientation reference (32), aligning the first orientation reference (31) in relation to a reference (14) by rotating it through the lockable rotation point (4) and subsequently locking said rotation point (4);

- after aligning the first orientation reference (31) and after locking the rotation point (4), aligning the second orientation reference (32) in relation to the reference (14).

22. A method according to claim 20, further comprising the following steps:

- fastening the orientation aid (1) with the first orientation reference (31) to the reference section (17) of the bone (11), which is different from the bone section (10), and with the first orientation reference (31) and the second orientation reference (32) being detachable from each other;

- after fastening the orientation aid (1), aligning the second orientation reference (31) in relation to the first orientation reference (31).

23. A method according to anyone of claims 20 to 22 for treating hip dysplasia.