FI126006B

FI126006B - Anatomically personified and mobilizing external support

Info

Publication number: FI126006B
Application number: FI20146121A
Authority: FI
Inventors: Roy Björkstrand
Original assignee: Aalto Korkeakoulusäätiö
Priority date: 2014-12-19
Filing date: 2014-12-19
Publication date: 2016-05-31
Also published as: FI20146121A7; WO2016097483A1

Description

ANATOMICALLY PERSONALIZED AND MOBILIZING EXTERNAL

SUPPORT

TECHNICAL FIELD OF THE INVENTION:

[0001] Aspects of the present invention relate to tissue-damage rehabilitation devices. In particular, aspects of the present invention relate to an anatomically personalized and mobilizing external support. Aspects of the present invention are further directed to the creation of an external support for damaged tissue, in order to support the tissue during rehabilitation. Additionally, aspects of the present invention relate to a method for controlling a path of a second external auxiliary frame of an anatomically personalized and mobilizing external support relative to a first external auxiliary frame.

BACKGROUND OF THE INVENTION:

[0002] As is known, the care of serious damage to a synovial joint resulting from accidents is challenging. For example, falling accidents often result in serious damage to the ankle, which is caused by the ankle bone impacting the cartilage surface of the tibia, which in the worst case can even lead to the crushing of the lower end of the tibia. Recovery from injuries like those described usually takes several months. In typical care following a falling accident, the damaged ankle is repaired operatively and fixed, i.e. supported rigidly, using, for example, locking and nonlocking plates and screws, Ilizahrov rings, and similar care accessories. However, in order to recover to full functionality, the cartilage requires nutrition, the transportation of which - unlike that in other tissues - is based on the tissue being loaded in cycles, so that fluid dynamics appear inside the cartilage. The recovery of cartilage is, for example, described in detail in the publication, ‘Influence of cyclic loading on the nutrition of articular cartilage’ (O’Hara B., Urban J., & Maroudas A., Ann. Rheum. Dis. 1990 July; 49(7): 536 - 539). If mobilization that transports nutrients is not arranged, the cartilage surface repaired by the operation may be destroyed, which will be followed in a couple of years by a state corresponding to osteoarthritis, i.e. invalidity. Precisely because osteoarthritis patients are mostly young people or those of working age, such as building workers, invalidizing osteoarthritis leads to not only personal misfortune, but also a significant economic cost.

[0003] In the publication ‘Articulated external fixation of the ankle: minimizing motion resistance by accurate axis alignment’ (Bottas M., March. L., & Brown T., Journal of Micromechanics, Vol. 32, No. 1, January 1999, pp. 63 - 70), it is stated that factors promoting recovery from, for example, the ankle-fracture injuries referred to above are protection from loads, early post-operative movement, a reduction in splinter fractures, and minimal disturbance of the injured area. For this reason, postoperative supports for damaged joints have been developed, so that in aftercare it will be possible to take into account mobilization of the joint as a precondition for recovery.

[0004] However, it should be noted that, besides the mobilization of a damaged joint, its correct timing is of considerable significance in the success of rehabilitation. Ankle mobilization, for example, cannot wait as long as the bone healing takes place in order to avoid post-traumatic stiffness. Correspondingly, a movement of the wrong kind can have disadvantageous consequences. It is therefore of decisive importance to find the joint’s anatomically correct path, in order to minimize the resistance to motion and avoid sudden damage caused by the wrong kind of movement. Thus, significant expectations are directed to post-operative supports, in relation to both being able to be rapidly installed and to creating the correct type of path.

[0005] Many external supports are known. However, the majority of supports intended for the aftercare of synovial joint injuries are either rigid, i.e. the supports do not permit therapeutic movement, or supports permitting movement, the motion permitted typically allows only a rotational movement and the location of the joint is a rough approximation of the real movement of the joint. In a simple model of an ankle, movement takes place around only a single axis of rotation, with a limited extent of movement. This is the simplest model of a moving joint, due to which it is used as an illustrative example in this connection. In other types of synovial joint, rotation and sliding in the direction of several axes or planes of movement can take place simultaneously. These can be controlled equally by means of the technology disclosed here. Rigid supports are, among others, Ilizahrov rings, which are external supports attached on both sides of the damaged joint. Ilizahrov rings are a way of implementing joint support that penetrates the tissue, i.e. it is invasive. In the method, the rings are attached to the patient’s bone by using tensioning cables and bone screws. Ilizahrov rings and their use are described in greater detail in the publications ‘Pilon fractures. Treatment protocol based on severity of soft tissue injury’ (Watson J. T., Moed B. R., Karges D. E., Cramer K. E.. Clin. Orthop. 2000; 375: 78 - 90) and ‘Two-ring hybrid external fixation of distal tibial fractures: A review of 47 cases' (Ristiniemi J., Flinkkilä T., Hyvönen P., Lakovaara M., Pakarinen H., Biancari F., Jalovaara P., J. Trauma 2007; 62: 174 - 183), the contents of which is included in this as a reference. In addition, non-invasive rigid supports are known, such as traditional plaster casts and similar. Supports permitting movement have been created, for example, by arranged external hinge-type plates, with the aid of which an attempt has been made to imitate the movement of the damaged joint. An example of the said plate in cases like the ankle fracture described above is a kind of pedal, on top of which the base of the foot is placed and which is adjusted to permit only such a tilting movement as would be natural for a healthy ankle.

[0006] Alternative methods are known for defining the natural movement of a synovial joint. In camera-based methods, the movement is recorded by using, for example, a video camera and alignment marks, which are attached to the object to be moved. After recording the movement, the preferably digital video material is analysed using special software and the movement information obtained with the aid of the alignment marks is captured, in order to form the path of movement. This method is utilized widely, for example, in sports applications and in the film industry, for which the technology was originally developed. Because the method does not require physical contact with the patient, the method is quite user-friendly from the patient’s point of view. The accuracy of the method varies from the accuracy required for making animations to the accuracy required for quality control. However, in the final resort the accuracy of the method depends on the resolution of the camera and on the measurement volume used. Typically, sufficiently accurate information is obtained by means of the method for animation of the movement of an entire limb, but this technology does not provide an answer to the movements of the bones that act as counter-surfaces in an individual joint.

[0007] A drawback of the method is that, in terms of the area of the theme of the invention, the method cannot be used to determine reliably the movement of the bones under the actual tissues, but rather the movement of the tissue on top of the bones. In addition, these methods do not reveal the fine-dynamic flexing under the soft tissue, i.e. the dynamics between the bones. Because it has not been possible to accurately define the precise anatomic movement, it has also not been possible, on the basis of these methods, to design anatomically personalized external supports.

[0008] An alternative to camera-based methods are three-dimensional or radiographic methods, in which a three-dimensional model of the bones is formed on the basis of either computer tomography (CT) or magnetic-resonance imaging (MRI). The methods are suitable for modelling the shape of an individual bone. MRI is not, however, suitable for situations in which non-MRI compliant screws are used - for example different kinds of steel screws or other attachment means - in the area of the joint already attached for old injuries or installed for the care of a new injury. In the said cases, CT imaging would be a possible method, but it suffers from imaging interference caused by metals and from the great radiation stress caused to the patient.

[0009] In known applications, a damaged synovial joint and its part are modelled on the basis of CT or MRI, when a virtual kinetic model corresponding to the damaged joint is obtained. This solution has been typically used in early motion analysis studies of cases of injury, because the technology used has been readily available in a hospital environment. For example, publication US2008312659 discloses a method for manufacturing a prosthesis, in which a patient-specific image, which is used as an aid in the manufacture of the prosthesis, is formed from data obtained from MRI imaging. For its part, publication US2007118243 discloses a method, in which a computer-based model, which is exploited to manufacture implants, prostheses, and similar, is created from data obtained on the patient’s anatomy in CT imaging. Though CT and MRI-based methods are indeed suitable for the manufacture of patient-specific artificial joints and other implants, the use of the said methods does not achieve sufficient accuracy as would permit preserving and saving a patient’s own joint after injury. Traditionally, it has been possible to achieve an accuracy of about 10 millimetres, whereas achieving a good result would require an accuracy of at least 1 ... 3 millimetres, preferably at least 0.5 millimetres. Typically, significant swelling also occurs in the area of a limb joint after injury, which reduces the accuracy if the definition of movement or the support is based on skin contact.

[0010] In general, significantly unknown tolerances relate to the technology used in the creation of bone models, which derive from the imaging quality and the grey-tome values available in sectioning. In addition, the joints, locations, and attitudes of three-dimensional models are fitted together visually in a 3D environment, which further reduces the method’s reliability and repeatability. Tolerance errors made in the creation of bone models accumulate, when the attachment points are designed on the basis of the models. All in all, at least up until now, the CT and MRI-based three-dimensional method have not been applied, because sufficient accuracy cannot be achieved using the methods.

[0011] Thus, problems are related to the determining of the path of a damaged joint. Because each joint, tissue, and injury is different, a statistical approximation and present modelling methods have not been able to provide a solution for creating an anatomically personalized support. More specifically, using present postoperative external supports, i.e. supports external to the body, it has not been possible to place artificial or auxiliary joints sufficiently precisely on the paths of movement of the joint, so that the mobilization of an injured limb or similar will not succeed, due to which the cartilage of the joint will not receive nutrition reliably. As stated, in mechanical design, as is known, reference geometries can be utilized, either by creating them in a three-dimensional 3D-CAD system, or by bringing a camera-based digital geometry to the design system, by using various methods and various formats. Challenges generally arise in the combination of a reliable design geometry, referencing digitalization, and a real application. Thus, the known joint supports have been rigid, which is not optimal from the point of view of the recovery of a joint.

[0012] Document WO 2011/042598 A1 discloses a method for providing a personalized and mobilizing external support for supporting moveably a synovial joint between a first bone group and a second bone group, wherein the movement between the first and the second bone groups is measured with the aid of a part of the external support invasively attached to at least one of said bone groups. Document WO 2011/042598 A1 further describes an anatomically personalized and mobilizing external support. The external support comprises at least one first external modular auxiliary frame, at least one second external modular auxiliary frame, at least one external modular auxiliary joint, and at least one personalized adapter component. The external support is configured to permit a rotation of the second external modular auxiliary frame relative to the first external modular auxiliary frame about an axis of rotation. The hinge component can further be shaped in such a way that it permits sliding of the rotational centre point and the alteration of the radius of the path.

[0013] In severe ankle traumas where Talus bone has damaged Tibia cartilage it is found that early mobilization improves healing results remarkably. It is also known that ankle movement is anatomically personal. The current method in trauma treatment is to fixate the ankle complex using a screw in Talus and a screw in Calcaneus and two in Tibia. Using fixators, ankle is fixated to prevent it from damage. A one-axis fixator joint apparatus can be attached as a part of the fixator to provide mobility. In clinical trauma treatment an external fixator is hardly ever located on right location since positioning is made freehand and typically based on unclear anatomical landmarks.

SUMMARY OF THE INVENTION:

[0014] An object of certain embodiments of the present invention is to provide an anatomically personalized and mobilizing external support. In particular, an object of certain embodiments of the present invention is to provide an anatomically personalized and mobilizing external support configured to be arranged to support a physical joint between a first and a second bone group. Additionally, an object of certain embodiments of the present invention is to provide a method for controlling a path of a second external auxiliary frame of an anatomically personalized and mobilizing external support relative to a first external auxiliary frame.

[0015] These and other objects are achieved by the embodiments of the present invention, as hereinafter described and claimed. According to an aspect of the invention, there is provided an anatomically personalized and mobilizing external support arranged to support a physical joint between a first and a second bone group, which support comprises: - at least one first external auxiliary frame, which is configured to be attached to the first bone group using invasive attachment means, - at least one second external auxiliary frame, which is configured to be attached to the second bone group using invasive attachment means, - wherein the external support is configured to permit: • a rotation of a portion of the second auxiliary frame about a first axis of rotation relative to another portion of the second auxiliary frame, and which said rotation causes • a rotation of the second external auxiliary frame about a second axis of rotation relative to the first external auxiliary frame.

[0016] In an embodiment, the external support is configured to permit a rotation of a first moveable mechanism of the second auxiliary frame relative to a second moveable mechanism of the second auxiliary frame about the first axis of rotation.

[0017] According to an embodiment, the external support is configured to vary an orientation of the first axis of rotation relative to the second axis of rotation during rotation of the first moveable mechanism.

[0018] According to another embodiment, the second moveable mechanism comprises a cylindrical inner surface and at least one groove in the cylindrical inner surface. In an embodiment, the at least one groove is configured to interact with a portion the first moveable mechanism. In another embodiment, an orientation of the at least one groove circumferentially varies in a direction of a centre axis of the cylindrical inner surface. According to an embodiment, a radius between an inner surface of the at least one groove and the centre axis of the cylindrical inner surface is essentially constant or constant.

[0019] In an embodiment, the second moveable mechanism comprises three grooves and the first moveable mechanism comprises a tripod configured to rotate about the first axis of rotation. In another embodiment, each end of an arm of the tripod is inserted into the respective groove of the second moveable mechanism.

[0020] According to an embodiment, the first moveable mechanism comprises a connector configured to rotate about the first axis of rotation and arranged to connect invasive attachment means to the first moveable mechanism. According to another embodiment, the first moveable mechanism comprises at least two bone screws, which are connected to the connector and arranged substantially parallel to the first axis of rotation.

[0021] In an embodiment, the first moveable mechanism comprises a cog wheel configured to rotate about the first axis of rotation. In another embodiment, the first auxiliary frame comprises at least a portion of a cog wheel configured to interact with the cog wheel of the first moveable mechanism of the second auxiliary frame.

[0022] According to an embodiment, an adapter component is connected to the first external auxiliary frame and is arranged to connect the second external auxiliary frame to the first external auxiliary frame via an external auxiliary joint.

[0023] According to another aspect, the object of the embodiments of the invention can be also achieved by a method for controlling a path of a second external auxiliary frame of an anatomically personalized and mobilizing external support relative to a first external auxiliary frame, the method comprising: • rotating a first portion of a second auxiliary frame relative to a second portion of the second auxiliary frame about a first axis of rotation, which rotating causes • rotating the second external auxiliary frame relative to a first external auxiliary frame about a second axis of rotation.

[0024] According to an embodiment, an orientation of the first axis of rotation is varied relative to the second axis of rotation during rotating the first portion of the second auxiliary frame.

[0025] According to another embodiment, anatomical landmarks of at least one bone group are measured before rotating the first portion of the second auxiliary frame relative to the second portion of the second auxiliary frame about the first axis of rotation.

[0026] Considerable advantages are obtained by means of the embodiments of the present invention. An anatomically personalized and mobilizing external support arranged to support a physical joint between a first and a second bone group is provided according to certain embodiments of the invention. Further, a method for controlling a path of a second external auxiliary frame of an anatomically personalized and mobilizing external support relative to a first external auxiliary frame is provided according to certain embodiments of the invention.

[0027] The external support provides a six degrees of freedom joint designed to meet personal anatomical movement, thus providing improved movability of an ankle and best healing results. Two or more separate mechanisms of the joint construction form one synchronous six degrees of freedom movement. The multi-axis movement of the external support is anatomically personalized and highly natural. Errors resulting from unintentional freehand positioning of the external support on a non-right location can be compensated. According to certain embodiments, the external support is designed and manufactured based on precise anatomical landmarks.

BRIEF DESCRIPTION OF THE DRAWINGS:

[0028] For a more complete understanding of particular embodiments of the present invention and their advantages, reference is now made to the following descriptions, taken in conjunction with the accompanying drawings. In the drawings:

[0029] Fig. 1 illustrates a schematic perspective view of an anatomically customized and mobilizing external support according to document WO 2011/042598 Al,

[0030] Fig. 2 illustrates a schematic perspective view of an external support according to an embodiment of the invention, and

[0031] Fig. 3 illustrates a schematic perspective view of an external support according to another embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION:

[0032] In Fig. 1 a schematic perspective view of an anatomically customized and mobilizing external support according to prior art document WO 2011/042598 Al is illustrated. A damaged joint 40 is surrounded by at least two bone groups: a first bone group 10 and a second bone group 20. The first bone group 10 is the Tibia and the second bone group 20 is the Talus and the Calcaneus. In this connection, a group of bones, which consists of at least one bone, is regarded as being a bone group. Immediately after the injury has occurred, the patient’s ankle is typically fixed, i.e. supported rigidly using splints, a plaster cast, an external attachment device (external fixator), or some other rapidly applicable means, by which movement of the ankle is prevented. Often, swelling caused by the injury prevents the fracture pieces from being immediately returned to their places and the related internal attachment using screws, spikes, plates, or other implants. If the soft-tissue situation permits, the ankle is operated on, in connection with which the pieces of cartilage are lifted off the tibia and returned to their original location. Traditionally, in the operation fixation is performed using an Ilizahrov or other rigid support device, which is known.

[0033] According to document WO 2011/042598 Al, in connection with the operation, auxiliary frames 12, 22 are placed around the damaged joint 40, with the aid of which an anatomically personalized and mobilizing external support can be designed, manufactured, and installed outside the joint 40, which will permit the joint 40 to be able to be moved to the correct extent in the correct directions, according to all the directions of movement required and measured in each joint. The auxiliary frames 12, 22 are attached invasively to the bone groups 10, 20 surrounding the joint 40, for example, using bone screws or various suitable cable arrangements. In this connection, the term invasive refers to a part penetrating tissue and the term external refers to a part outside the tissue. In Figure 1, two invasive bone screws 21, which form the second attachment means, are attached to the second bone group 20. The first auxiliary frame 12, which is attached to the first bone group 10 invasively with the aid of the first attachment means, which comprise the bone screws and cables according to Figure 1, is fitted to the first bone group 10 surrounding the joint 40. The first auxiliary frame 12 is preferably, for example, an Ilizahrov ring arrangement, which is easy to fit to the Tibia. In the attachment of the auxiliary frame, the actual attachment point is, according to the invention, of no particular importance: the attachment point, for example for bone screws, is chosen on the conditions of the best possible contact and the most accommodating soft-tissue situation. Also the position and attitude of the auxiliary frame 12, 22 can be selected quite freely, but, however, in such a way that the distance of the closest point of the auxiliary frame from the coming external auxiliary joint is the smallest possible, either by visual estimate or by calculation.

[0034] Document WO 2011/042598 A1 also describes that the second auxiliary frame 22 fitted to the second bone group 20 comprises the heads of the bone screws 21. Alternatively, the second auxiliary frame 22 could be, for example, a horseshoe-shaped ring resembling an Ilizharov ring, which is attached to the second bone group by bone screws 21. Generally, the auxiliary frame can be an arbitrary component, which can be fixed to the bone group and to which an auxiliary joint 30 or adapter 32 can be fitted externally.

[0035] Additionally, document WO 2011/042598 A1 teaches that once the injured joint 40 has been repaired in an operation and the external auxiliary frames 12, 22 have been fitted to the bone groups 10, 20 surrounding the joint 40, the movement of the joint 40 is modelled for the design of a correct type of mobilizing external support. Immediately after the operation, the joint 40 is, however, fixed temporarily, for example for a couple of days, by securing the auxiliary frames 12, 22 to each other by a suitable intermediate part. Prior to this the movement is modelled preferably using a digitalization device, by means of which numerical and correct information is created. In this connection, the term digitalization refers to a device, by means of which movement information can be captured from a physical object and data, such as a set of coordinates, for processing is created. The digitalization device may be a coordinate device by means of which in the best case accuracy of as much as 0.05 millimetres can be obtained. Alternatively, it is possible to use, for example, a three-dimensional laser scanner, or camera based device.

[0036] In the measuring process according to document WO 2011/042598 Al, the intention is to obtain information of the kinetic dynamics of the joint, i.e. as to study the bone groups around the joint move relative to each other, by means of the joint. More specifically, in the measurement, the movement between the first and second bone groups 10, 20 in respect to the joint 40 is measured with the aid of the auxiliary frames 12, 22 attached to the bone groups 10, 20 by attachment means 21. The coordinates of the measurement points of the auxiliary frame 12 attached to the first bone group 10, i.e. the Tibia, are measured first. Once the locations of the measurement points of the auxiliary frame 12 of the first bone group 10 have been measured, the path of the measurement point or points of the second auxiliary frame 22 relative to the first auxiliary frame 12 is measured. In camera based systems measurements are taken simultaneously.

[0037] After, or during the measurements, the measurement data is transferred to a CAD system according to document WO 2011/042598 Al. The measurement data is transferred from the coordinate measuring device directly to the CAD system. Alternatively, the information can also be recorded in a file, from which the measurements points are loaded as points into the CAD program. Once the measurement information is in the CAD system, the kinetic dynamics of the joint 40 are modelled on the basis of the information. In the modelling of the kinetic dynamics 60, the movement of the joint 40 can be approximated and modelled very accurately on the basis of the measurements obtained from the second auxiliary frame 22. In a joint comprising several degrees of freedom, each rotation and sliding movement combination is defined, as well as their mutual rhythm in each plane in a corresponding manner.

[0038] Document WO 2011/042598 Al further teaches that a CAD model is arranged from the auxiliary frames 12, 22. The components used, such as the auxiliary frames 12, 22, the attachment means 21, and the auxiliary joint 30 may be, for example, standard components, of which there are ready-made CAD models. In addition, a CAD model is arranged of the auxiliary joint 30 used in the external support. The auxiliary joint 30 is preferably of a general-purpose model and a simple, readily available hinge-type pin joint, the path permitted by which can be limited mechanically. The hinge component can further be shaped according to modelling, in such a way that it permits sliding of the rotational centre point and the alteration of the radius of the path. This is necessary, for example, when modelling the movements of the knee.

[0039] Subsequently, document WO 2011/042598 A1 furthermore discloses that once the kinetic dynamics of the joint 40 have been created in the CAD system, the arranged CAD models of the auxiliary frames 12, 22 are adapted to the path in the CAD system. In the case of the ankle example, the surface of the first auxiliary frame 12 closest to the second auxiliary frame 22 is placed, on the basis of the measurement results, in an attitude on the created plane, in which the measurement points coincide with each other. Correspondingly, the CAD model of the auxiliary joint 30 is placed on the path, in such a way that the axis of the auxiliary joint 30 and the axis of the path coincide, so that the CAD model of the auxiliary joint 30 simulates the joint permitted by the path brought into the CAD system. Preferably, the kinetic centre point of the model of the auxiliary joint 30 coincides with the centre point 62 of the modelled motion. Once the length of the path is known on the basis of the model of the path, the extent of motion of the real auxiliary joint 30 is adjusted preferably to correspond to the measured natural extent of motion of the joint 40. Correspondingly, the CAD model of the second auxiliary frame 22 is aligned in place in the CAD system on the basis of the model of the path. The modelled measurement point or points are also preferably modelled in the CAD model of the second auxiliary frame 22.

[0040] Additionally, document WO 2011/042598 A1 discloses that once the auxiliary frames 12, 22 and the auxiliary joint 30 have been adapted in the CAD system to the created path model, the necessary adapter components 31, 32 for connecting the auxiliary joint 30 to the auxiliary frames 12, 22 are modelled in the system. In some cases, the auxiliary joint 30 can be adapted to be connected directly to the auxiliary frame 12, 22, in which case only a single adapter component 31, 32 will be required. An adapter component 31, 32 may be designed between both the first and the second auxiliary frame 12, 22 and the joint 30. It is particularly advantageous to design the adapter components 31, 32 directly in the CAD system to connect the joint 30 and the auxiliary frames 12, 22, in which case drawings for manufacture can be obtained especially easily from the CAD models of the components 31, 32. The adapter components 31, 32 may be manufactured using a 3D printer, or by some other instant manufacturing method, by means of which it is possible to manufacture, for example, polymer parts directly with the aid of CAD models. Alternatively, it is possible to use some other CAD-CAM system, by means of which a component of sufficient strength can be created, and which can be manufactured rapidly.

[0041] Once the adapter components 31, 32 have been manufactured, they are fitted to the corresponding auxiliary frames 12, 22. The auxiliary joint 30 is fitted between the adapter components 31, 32, in which case an anatomically personalized and mobilizing external support is created outside the joint 40 between the first and second bone groups 10, 20. As stated, the auxiliary joint 30 is preferably adjustable, in such a way that the angle between it and the movement of the actual joint 40 can be adjusted. Immediately after the operation, the auxiliary joint 30 is adjusted, preferably in such a way that the movement between the first and second bone groups 10, 20 does not permit the bone groups to fix. During the period of post-operative rehabilitation, the path and angle of the movement permitted by the auxiliary joint 30 is adjusted on the basis of the CAD model of the path to be anatomically correct and the extent of the paths of motion can be adjusted as required as care progresses.

[0042] In the following, certain embodiments of the external support according to the present invention are examined in greater detail in Fig. 2 and 3. Features of the external support described above can be also used in the embodiments of the external support described below.

[0043] In Fig. 2 a schematic perspective view of an external support according to an embodiment of the invention is illustrated. The anatomically personalized and mobilizing external support is configured to be arranged to support a physical joint 40 between a first bone group 10 and a second bone group 20. The bone groups 10, 20 and the physical joint 40 are not shown in Fig. 2.

[0044] The external support comprises at least one first external auxiliary frame 12, which is configured to be attached to the first bone group 10 using invasive attachment means 21, and at least one second external auxiliary frame 22, which is configured to be attached to the second bone group 20 using invasive attachment means 21. The first external auxiliary frame 12 may, for example, comprise so called Ilizahrov rings. The rings are then attached to the patient’s bone by using tensioning cables and/or bone screws as invasive attachment means 21. The term “invasive” refers to a part penetrating tissue and the term “external” refers to a part outside the tissue. The first external auxiliary frame 12 of the external support according to the present invention is not shown in Fig. 2. Instead of Ilizahrov rings, a so called monotube, which comprises a tubular component connected to invasive attachment means 21, which are attached to the first bone group 10, can be used according to certain embodiments.

[0045] The second external auxiliary frame 22 is rotatably connected to an adapter component 31, which is connected to the first external auxiliary frame 12 and is arranged to connect the second external auxiliary frame 22 to the first external auxiliary frame 12 via an external auxiliary joint 30. The personalized adapter component 31 may be, for example, an integral part of the first external auxiliary frame 12. According to certain other embodiments, the personalized adapter component 31 can be a separate part which is to be attached to the first external auxiliary frame 12. The personalized adapter component 31 comprises a portion of a cog wheel 101. The portion of the cog wheel 101 may be, for example, attached to the personalized adapter component 31 by means of screws, adhesive, or any other suitable attachment means. According to certain embodiments, the portion of the cog wheel 101 may be an integral part of the personalized adapter component 31.

[0046] The second auxiliary frame 22 comprises an outer section and an inner section. The inner section can be considered as “first moveable mechanism” and the outer section can be considered as “second moveable mechanism”. The outer section of the second auxiliary frame 22 comprises a movable module 102 including a cylindrical or conical inner surface 103. The moveable module 102 is typically formed as a ring-like element having a cylindrical inner surface 103. At least one groove 104 is arranged in the inner surface 103 of the module 102. According to certain embodiments, three or more groves 104 are arranged in the inner surface 103 of the module 102. The radius between a circumferential inner surface 110 of the groove 104 and the centre axis of the cylindrical inner surface 103 is typically substantially constant or constant. The orientation of the at least one groove 104 in the direction of the centre axis of the cylindrical inner surface 103 is personalized. In other words, the three-dimensional form of the groove 104 is depending on a measured natural path of the movement of e.g. the ankle complex. The orientation of the grooves 104 varies circumferentially in a direction of a centre axis of the cylindrical or conical inner surface 103. In other words, the grooves 104 are not formed ring-like. Each different external support may therefore have different grooves 104 depending on the natural movement of two bone groups relative to each other.

[0047] Additionally, the outer section includes a bearing 105 in order to support a rotatable shaft of the first moveable mechanism. The bearing 105 may be, for example, formed by an element shaped in the form of an “X” such as shown in Fig. 4, which element is attached to the module 102 of the second moveable mechanism and comprises an opening in the centre of the circular opening 106 of the hollow module 102. According to certain embodiments, the baring may be, for example, formed by two longitudinal elements which extend from one side of the module 102 to the other side of the module 102 and cross each other in the centre of the circular opening 106 of the module 102, and wherein a boring or opening is located at the cutting point of the differently orientated longitudinal elements through both longitudinal elements. According to certain embodiments, the bearing 105 may be, for example, formed by one single longitudinal element extending from one side of the module 102 to the other side of the module 102 and comprising an opening in the centre of the circular opening 106 of the hollow module 102.

[0048] The inner section of the second auxiliary frame 22, i.e. the first moveable mechanism, comprises a shaft which is to be mounted in the boring or opening of the bearing 105. At one end of the shaft a cog wheel 107 is arranged which is adapted to interact with the portion of a cog wheel 101 of the first auxiliary frame 12. On the other side of the bearing 105 a so called tripod 108 is connected to the shaft. In this document, a tripod 108 has three arms which are located at an angle of 120° to each other in a plane. In the centre of the tripod 108 there is arranged a means for connecting the tripod 108 to the shaft of the first moveable mechanism. The ends of the arms of the tripod 108 are configured to be inserted into three grooves 104 of the moveable module 102 of the outer section of the second auxiliary frame 22, i.e. the second moveable mechanism. Further, a connector 109 is attached to the shaft or to the tripod 108. Two bone screws 21 are furthermore connected to the connector 109 as invasive attachment means. The connector 109 is configured to rotate about the first axis of rotation 111 and arranged to connect the invasive attachment means 21 to the first moveable mechanism. The cog wheel 107, the tripod 108, the connector 109, and the bone screws 21 are configured to simultaneously rotate about the first axis of rotation 111.

[0049] Movement of the ankle leads to a rotation of the tripod 108 around the first axis of rotation 111. The tripod 108 is guided by the three grooves 104 located in the cylindrical inner surface 103 of the module 102 of the second moveable mechanism. The orientation of the first axis of rotation 111 relative to the second axis of rotation 100 will vary during rotating the tripod 108 of the first moveable mechanism due to the form of the grooves 104. The guided movement represents a side-to-side translation and rotation in three dimensions. The first moveable mechanism of the second auxiliary frame 22 can be also considered as so called “master mechanism”.

[0050] The gear connected to the tripod 108 and formed by the cog wheel 107 of the first moveable mechanism of the second external auxiliary frame 22 and the pinions of the portion of a cog wheel 101 of the first external auxiliary frame further forces the second external auxiliary frame 22 to simultaneously rotate relative to the first external auxiliary frame 12 about the second axis of rotation 100 via the joint 30. The second moveable mechanism of the second auxiliary frame 22 can be therefore also considered as so called “slave mechanism”. The swinging movement represents up-down as well as front-back movements. In total, the external support according to certain embodiments of the present invention provides a synchronous movement having six degrees of freedom.

[0051] In Fig. 3 a schematic perspective view of an external support according to another embodiment of the invention is illustrated. The anatomically personalized and mobilizing external support is to be arranged to support a physical joint 40 between a first and a second bone group 10, 20, which support comprises at least one first external auxiliary frame 12, which is configured to be attached to the first bone group 10 using invasive attachment means 21, and at least one second external auxiliary frame 22, which is configured to be attached to the second bone group 20 using invasive attachment means 21. The first external auxiliary frame 12 as well as the first bone group 10 and the second bone group 20 are not shown in Fig. 3.

[0052] The external support is configured to permit a rotation of a portion of the second auxiliary frame 22 relative to another portion of the second auxiliary frame 22 about a first axis of rotation 111, which said rotation causes a rotation of the second external auxiliary frame 22 relative to the first external auxiliary frame 12 about a second axis of rotation 100.

[0053] Generally, reference geometries and ankle movement information is transferred to a computer aided design environment (3D-CAD) in the design procedure of the external support in order to form an anatomical reference frame showing sagittal, frontal and axial planes based on measured landmarks. The spatial movement is then split into six components by projections on said frame. The standard parts of the joint are located in the virtual environment such that the mechanism's translation directions are arranged parallel to the mentioned frame planes. Subsequently, the fixation attachment parts are designed. Then the movement and the components are analysed.

[0054] The results of the design procedure are used to dimension and manufacture the translation and rotation controls of the external support. The results may be also used to automatically configure pre-designed parts. The pre-designed parts may be adapted to anatomically personal dimensions. In particular, the adapter component 31 of the first auxiliary frame 12 and the at least one groove 108 in the cylindrical or conical inner surface 103 of the second moveable mechanism may be anatomically personalized according to certain embodiments of the invention. Personalization may take place manually or by means of a computer aided algorithm based on the measured landmarks. Synchronization of the master mechanism and the slave mechanism can be also analysed and optimized, thus resulting in a personalized set of personalized components. Of course, any part of the external support can be anatomically personalized according to certain embodiments of the invention, if required.

[0055] Although the present invention has been described in detail for the purpose of illustration, various changes and modifications can be made within the scope of the claims. In addition, it is to be understood that the present disclosure contemplates that, to the extent possible, one or more features of any embodiment may be combined with one or more features of any other embodiment.

[0056] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

List of reference numbers: 10 first bone group 12 first external modular auxiliary frame 20 second bone group 21 invasive attachment means 22 second external modular auxiliary frame 30 external auxiliary j oint 31 first adapter component 32 second adapter component 40 joint 100 second axis of rotation 101 portion of cog wheel 102 module 103 circular inner surface 104 groove 105 bearing 106 opening 107 cogwheel 108 tripod 109 connector 110 inner surface of groove 111 first axis of rotation

Claims

Anatomically personalized mobilizing external support arranged to support a physical joint (40) between the first and second bone groups (10, 20), wherein the support comprises: at least one first external subframe (12) configured to be attached to the first bone group (10) using an invasive securing means (21), - at least one second external subframe (22) configured for attachment to the second bone assembly (20) using an invasive attachment means (21), - wherein the external support (1) is configured to allow: rotation of a portion of the second subframe (22); rotating the first axis of rotation (111) relative to the second portion of the second subframe (22), and said rotation causing • rotation of the second outer subframe (22) around the second axis of rotation (100) relative to the first external subframe (12).

The anatomically personalized and mobilizing external support of claim 1, wherein the second subframe is configured to allow: rotation of the first movable mechanism of the second subframe (22) with respect to the second movable mechanism of the second subframe (22) about the first axis of rotation (111).

The anatomically personalized mobilizing external support of claim 2, wherein the external support is configured to vary the orientation of the first axis of rotation (111) relative to the second axis of rotation (100) during rotation of the first movable mechanism.

The anatomically personalized mobilizing outer support according to claim 2 or 3, wherein the second movable mechanism comprises a cylindrical or conical inner surface (103) and at least one groove (104) on the cylindrical or conical inner surface (103).

The anatomically personalized mobilizing external support of claim 4, wherein said at least one groove (104) is configured to interact with a portion of the first movable mechanism.

The anatomically personalized mobilizing outer support according to claim 4 or 5, wherein the orientation of said at least one groove (104) in a circumferential direction varies with the central axis of the cylindrical or conical inner surface (103).

The anatomically personalized mobilizing outer support of claim 6, wherein the radius between the inner surface (110) of said at least one groove (104) and the central axis of the cylindrical inner surface (103) is substantially constant or constant.

The anatomically personalized mobilizing external support according to any one of claims 4 to 7, wherein the second movable mechanism comprises three grooves (104) and the first movable mechanism comprises a tripod (108) configured to rotate about the first axis of rotation (111).

The anatomically personalized mobilizing external support of claim 8, wherein each end of the arm of the tripod (109) is inserted into a corresponding groove (104) of the second movable mechanism.

The anatomically personalized mobilizing external support according to any one of claims 2 to 9, wherein the first movable mechanism comprises a connector (109) configured to rotate about the first axis of rotation (111) and subsequently coupled to engage the first movable mechanism.

The anatomically personalized mobilizing external support of claim 10, wherein the first movable mechanism comprises at least two bone screws (21) connected to the connector (109) and tracked substantially parallel to the first axis of rotation (111).

The anatomically personalized mobilizing external support according to any one of claims 2 to 11, wherein the first movable mechanism comprises a gear (107) configured to rotate about a first axis of rotation (111).

The anatomically personalized mobilizing external support of claim 12, wherein the first subframe comprises at least a portion of the sprocket (101) configured to interact with the first movable mechanism of the second subframe (107).

The anatomically personalized external support according to any one of claims 1 to 13, wherein the adapter component (31) is connected to the first external subframe (12) and is mated to connect the second external subframe (22) to the first external subframe (12) via an external auxiliary joint.

A method for controlling the path of an anatomically personalized and mobilizing external support second outer subframe (22) relative to the first external subframe (12), the method comprising: rotating a first portion of the second subframe (22) relative to a second portion of the second subframe (22); rotation axis (111), where rotation causes the second outer subframe (22) to rotate relative to the first external subframe (12) about the second rotary axis (100).

The method of claim 15, further comprising: varying the orientation of the first axis of rotation (111) relative to the second axis of rotation (100) during rotation of the first portion of the second subframe (22).

The method of claim 15 or 16, further comprising: measuring anatomical markers of at least one set of bones (10, 20) before rotating the first portion of the second subframe (22) relative to the second portion of the second subframe (22) of the first axis of rotation (22). 111) around.