WO2011123951A1

WO2011123951A1 - Frontal joint mechanism for orthotic devices

Info

Publication number: WO2011123951A1
Application number: PCT/CA2011/000397
Authority: WO
Inventors: Dany Lachance; Stéphane BÉDARD
Original assignee: B-Temia Inc.
Priority date: 2010-04-06
Filing date: 2011-04-04
Publication date: 2011-10-13

Abstract

A frontal joint mechanism to be coupled to an orthotic device having a distal and a proximal support elements linked together by a joint component, comprising a first displacement element connected to the joint component, a second displacement element connected to the distal or the proximal support element and a rigid link connecting the first and the second displacement elements. The combination of the first and second displacement elements provides rotational and translational displacements in the coronal plane of the distal support element with respect to the proximal support element of the orthotic device.

Description

FRONTAL JOINT MECHANISM FOR ORTHOTIC DEVICES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefits of U.S. provisional patent application No. 61/282,817 filed on April 6, 2010, which is herein incorporated by reference.

TECHNICAL FIELD

[0002] The present disclosure relates to a frontal joint mechanism for orthotic devices.

BACKGROUND

[0003] All joint-segments structures of the human body comprise complex joint rotational mobility with multiple degrees-of-freedom (DOFs) in order to execute a set of infinite movements that are essential for the mobility of body limbs. For upper extremities, this multiple DOFs mobility is critical for the performing of basic daily-life movements. More importantly, it is mandatory that each joint-segments body structure DOF of the three biomechanical planes (sagittal, coronal and transversal) have full range-of-motion (ROM) in order to adequately move the upper extremities in all directions. For the wrist, the elbow, the shoulder and the neck, at least one DOF for each biomechanical plane with the right ROM becomes the bottom line in respective upper extremities biomechanics. For the lower extremities, despite most of the metabolic energy expenditure coming from motions in the sagittal plane during locomotion, the rotational mobility into the two other biomechanical planes, the coronal plane and the transversal plane, is essential to perform a natural and low energy-cost locomotion. From a biomechanical point of view, for each lower extremity joints (i.e. the hip, the knee and the ankle) the lateral DOFs in the sagittal plane and the frontal DOFs in the coronal plane are part of a natural walking path.

[0004] From basic biomechanical principles, it becomes obvious that, for the upper and the lower extremities, the frontal DOFs, permitting rotation and translation movements in the coronal plane, are an important part of the limb's

2285375.1 mobility. Without these specific DOFs, basic movements of upper extremities become impossible and the whole locomotion is jeopardized.

[0005] Common orthotic devices are crafted to precisely secure the joint- segments body structures against biomechanical dislocation while unfortunately secluding the mobility of the body structure into one biomechanical plane, i.e. the sagittal plane. In general, these devices are provided with efficient joint mechanisms providing a biomechanically compatible ROM for the rotation around the transversal axis (sagittal plane) but do not address the two other rotation axes and more specifically the antero-posterior axis (coronal plane).

[0006] Based on these last observations, it clearly appears that there is a need for an improved orthotic device that assist a user to maintain, restore or enhance the kinematic and kinetic properties of a targeted joint-segments body structure without applying undesired forces or torque on the segments of the joint- segments body structure.

SUMMARY

[0007] The present disclosure provides a frontal joint mechanism for orthotic devices allowing biomechanically compatible mobility in the coronal plane, providing additional degree-of-freedom movement for the upper extremities as well as a more natural walking path during locomotion. The frontal joint mechanism for orthotic devices is designed to provide additional mobility in the coronal plane for any orthotic device aimed at stabilizing, maintaining, restoring or enhancing the biomechanical capability of a given joint-segments body structure.

[0008] In the case of a passive orthotic device specifically designed to stabilize a given joint-segments body structure, the integration of the frontal joint mechanism improves the biomechanical capacity of the orthotic device to adequately secure the body structure because the device tends to more naturally follow the complex mobility pattern of the joint.

[0009] For an active orthotic device equipped with a motorized joint, the frontal joint mechanism provides improved synchronization of the motion of the

2285375.1 motorized device with the natural biomechanics of the joint-segments body structure. A high level of synchronization between the active orthotic device and the body structure is mandatory when the supporting device is powered. Assisting a given joint-segments structure with an active orthotic device and excluding complex DOF mechanism at the respective apparatus' pivot component produces misalignments between the both motions, i.e. forced movements supplied by the active orthotic device and the natural movements intrinsic to the body structure, that would induce directly acute and chronic joint-related injuries.

[0010] The frontal joint mechanism is designed to be part of the main pivot component of the orthotic device responsible for the rotational mobility at the transversal axis in the sagittal plane. In an illustrative embodiment of the present disclosure, the frontal joint mechanism is positioned between the main pivot and a distal support element of the orthotic device. The frontal joint mechanism works in mechanical connection with the supporting device's main pivot by adding one or more DOF along the antero-posterior axis in the coronal plane. In the illustrative embodiment, the frontal joint mechanism includes two DOFs that work independently: a rotation motion and a transversal motion. This allows linear and angular displacements of the distal support element with respect to the proximal support element in the coronal plane.

[0011] Accordingly, the present disclosure provides a frontal joint mechanism to be coupled to an orthotic device having a distal and a proximal support elements linked together by a joint component, comprising:

a first displacement element connected to the joint component;

a second displacement element connected to the distal or the proximal support element; and

a rigid link connecting the first and the second displacement elements;

wherein the combination of the the first and second displacement elements provides rotational and translational displacements in the coronal plane of the

22S5375.1 distal support element with respect to the proximal support element of the orthotic device.

[0012] In an alternative embodiment of the present disclosure, there is provided a frontal joint mechanism to be coupled to an orthotic device having a distal and a proximal support elements linked together by a joint component, comprising:

a displacement element connected to the joint component and to the distal or to the proximal support element; wherein the displacement element provides rotational and/or translational displacement in the coronal plane of the distal support element with respect to the proximal support element of the orthotic device.

[0013] There is further provided a frontal joint mechanism as any of the above wherein the displacement elements are rotational elements allowing rotational displacement in the coronal plane, compliant elements allowing rotational and/or translational displacements in the coronal plane or a combination thereof, allowing rotational and/or translational displacements in the coronal plane; wherein the rotational displacement is parallel to the antero-posterior axis of the orthotic device.

BRIEF DESCRIPTION OF THE FIGURES

[0014] Embodiments of the disclosure will be described by way of example only with reference to the accompanying drawings, in which:

[0015] Figure 1 is a perspective view of an example of an orthotic device including a frontal joint mechanism in accordance with an illustrative embodiment of the present disclosure;

[0016] Figure 2 is a perspective view of the frontal joint mechanism including two degrees-of-freedom in the coronal plane in accordance with an illustrative embodiment of the present disclosure;

2285375.1 [0017] Figures 3A and 3B are perspective front views of a lower portion of the orthotic device of Figure 1 illustrating the first main degree-of-freedom; and

[0018] Figures 4A and 4B are perspective front views of a lower portion of the orthotic device of Figure 1 illustrating the second main degree-of-freedom.

DEFINITIONS

[0019] The detailed description and figures refer to the following terms which are herein defined:

Distal: situated away from the center of the body (i.e. the heart); and

Proximal: situated towards the center of the body (i.e. the heart).

DETAILED DESCRIPTION

[0020] Generally stated, the non-limitative illustrative embodiment of the present disclosure provides a frontal joint mechanism for orthotic devices that allows mobility in the coronal plane during locomotion.

[0021] An orthotic device's goal is to assist a user maintain, restore or enhance the kinematic and the kinetic properties of a targeted joint-segments body structure by assisting it in one or more degrees-of-freedom (DOFs) while keeping the other DOFs unconstrained. The main DOFs generally include the rotation at the transversal axis in the sagittal plane, but without applying undesired forces or torque on the segments of the joint-segments body structure. Such undesired forces or torques exert additional stress on the joint and may lead to user discomfort or even injury. To avoid reactive forces or torques from developing between the body segments and the orthotic device, it is then necessary to allow free motion of the distal element with respect to the proximal element of the orthotic device in all other directions.

[0022] Each joint-segments structure of the human body has up to six DOFs; three biomechanical planes and two types of motion, namely rotation and translation. In the design of an orthotic device providing biomechanical assistance, some DOFs must be taken into account because of their high level biomechanical

2285375.1 constraint at the joint while other DOFs may be ignored because their involvement in terms of biomechanical constraint and metabolic energy expenditure is relatively low compared to others.

[0023] For most cases, the lateral rotation DOF in the sagittal plane is the main DOF in overall mobility because its biomechanics is highly active for any kind of movements, as much for the upper as for the lower extremities. The importance of the five remaining DOFs is strongly dependant on the application, that is to say the joint itself and what kind of environment the joint has to evolve in.

Knee-Thigh/Shank Structure Embodiment

[0024] Regarding the knee-thigh/shank structure, the main DOF for all joint- segments structures of the lower extremities is the lateral rotation DOF in the sagittal plane because the biomechanical (kinematic and kinetic) properties in the sagittal plane shows the highest level of range-of-motion and torque at the joint- segments structure during locomotion movements.

[0025] For the knee-thigh/shank structure, there are two other DOFs that are considered important for any design of active (motorized) assistive apparatus (i.e. orthotic device): the frontal rotation in the coronal plane; and the frontal translation in the coronal plane.

[0026] For the frontal rotation in the coronal plane, this constraint can cause reaction torque in the coronal plane to develop between the leg segments in the case of non-zero valgum/varum of the user's leg. This torque comes from lateral compression forces between the orthotic device and the leg tissues, and the forces involved are deemed to be considerable. This constraint should be eliminated in order to avoid undesired torque at the knee in the coronal plane. For the frontal translation in the coronal plane, the constraint can cause a reaction force along the transversal axis to develop between the leg segments in the case where the user's leg is not perfectly aligned with the proximal and distal support elements of the orthotic device (due to different muscle sizes). This force is the result of

2285375.1 compression forces between the orthotic device and the leg tissues, and the forces involved are deemed to be high. This constraint should be eliminated in order to avoid undesired force at the knee along the transversal axis.

[0027] Concerning the three remaining DOFs, namely the longitudinal rotation in the transversal plane, the longitudinal translation in the transversal plane and the lateral translation in the sagittal plane, it may be assumed that the constraints exerted by the DOFs are at a negligible level.

[0028] For the longitudinal rotation in the transversal plane, this constraint would cause reaction torque in transversal plane to develop between the two leg segments. This reaction torque is based on tangential shearing forces between the leg tissues and the orthotic device. Such shearing forces are deemed to be significantly lower than compressive forces between the orthotic device and the leg tissues. Since there are no positive contact forces between the leg and the orthotic device to constrain this rotation, the magnitude of the associated reaction torque is low. The constraint is assessed as a weak constraint and is deemed acceptable.

[0029] For the longitudinal translation in the transversal plane, the related constraint can cause a reaction force along the leg's longitudinal axis to develop between the two leg segments. This reaction force is based on vertical shearing forces between the leg tissues and the orthotic device contact elements. Such shearing forces are deemed to be significantly lower than compressive forces since there is no positive contact between the leg and the orthotic device. The magnitude of the associated reaction force is low. Therefore, the constraint is assessed as being at a low level.

[0030] For the lateral translation in the sagittal plane, this constraint can cause a reaction force along the antero-posterior axis to develop between the two leg segments. This reaction force is caused by compression forces on the leg segments along the antero-posterior axis. These forces are necessary to provide sagittal plane torque at the knee and cannot be eliminated. This last constraint cannot be easily removed, since a single translation mechanism along anteroposterior axis can generate this specific reaction force. However, this constraint

2285375.1 can be minimized by allowing proper adjustment of the orthotic device contact elements on the leg in the antero-posterior axis.

[0031] Accordingly, the present disclosure provides an adjustment mechanism designed to properly adjust the contact elements of the orthotic device to the user's leg and avoid undesired contact forces along this axis. To avoid the occurrence of undesired contact forces, the orthotic device should be adjusted for each user. At rest, the contact elements should be in contact with the leg, but no pressure should be felt by the user at the contact elements. When the orthotic device applies torque at the knee, the reactions forces developing at each of the contact elements should be equal in magnitude and in opposed directions (for each body segment), thus resulting in a net reaction force in the antero-posterior axis of zero for both body segments. This constraint is then under control as long as proper adjustment is made.

Frontal joint mechanism

[0032] Referring to Figure 1 , there is shown an example of an orthotic device 100 for the knee joint that includes a proximal support element 1 10 for transferring torque from the compensating joint 130 to the upper leg segment of a user via contact elements 1 12 and a distal support element 120 for transferring torque from the compensating joint 130 to the lower leg segment of the user via the frontal joint mechanism 140, having two DOFs, and contact elements 122 in accordance with an illustrative embodiment of the present disclosure.

[0033] The purpose of the frontal joint mechanism 140 is to allow two DOFs free motion between the proximal 1 10 and distal 120 support elements of the orthotic device 100 without impairing its primary function, which is to provide opposite torques to both leg segments in the sagittal plane.

[0034] Referring now to Figure 2, the frontal joint mechanism 140 comprises, as mentioned above, two DOFs provided via two displacement elements 141 and 142, which in the illustrative embodiment are two parallel axis revolution joints, linked by a rigid link 143. The frontal joint mechanism 140 is oriented in such a way that the axes of both revolution joints 141 and 142 are

2285375.1 parallel to the antero-posterior axis of the orthotic device 100, forming a plane parallel to the sagittal plane. The frontal joint mechanism 140 is secured between the compensating joint 130 and the distal support element 120 by two end attachments 144 and 145.

[0035] Referring to Figures 3A and 3B, the proximal revolution joint 141 allows free rotation of the rigid link 143 with respect to the proximal end attachment 144 which causes a lateral displacement 1 of the axis of the distal revolution joint 142. This lateral displacement 1 of the axis of the distal revolution joint 142 constitutes the first main DOF exerting a frontal translation of the distal support element 120 along the transversal axis in the coronal plane.

[0036] Referring now to Figures 4A and 4B, the distal revolution joint 142 allows free rotation 2 of the distal support element 120 with respect to the rigid link 143. This free rotation 2 of the distal support element 120 is the second main DOF.

[0037] The combination of both revolution joints 141 and 142 provides all of the combinations of frontal translation, along the transversal axis in the coronal plane, and frontal rotation, in the coronal plane, of the distal support element 120 of the orthotic device 100 with respect to the proximal end attachment 144 of the frontal joint mechanism 140.

[0038] Since the axes of both revolution joints 141 and 142 are perpendicular to the main axis of the orthotic device's 100 joint (i.e. compensating joint 130), which is the transversal axis, the torque component coming from the compensating joint 130, passively or actively produced, is fully transferred through the frontal joint mechanism 140 without loss, and is fully applied to the distal support element 120. Consequently, there is no undesired residual torque or lateral force developing in the frontal plane when the orthotic device 100 is under load, i.e. the torque passively or actively applied to the transversal axis of the orthotic device's 100 joint.

[0039] In the illustrative embodiment, the displacement elements 141 and 142 may be in the form of rotational elements such as pivots, hinges, spring mechanisms or any other such mechanisms, either passive or active (i.e. actuated,

2285375.1 providing additional energy). In an alternative embodiment, the displacement elements 141 and 142 may be compliant elements, for example a semi-rigid material such as a high density polymer. In a further alternative embodiment, the displacement elements 141 and 142 may be a combination of the above.

[0040] In another alternative illustrative embodiment, the frontal joint mechanism may be provided with a single displacement element. If the provided displacement element is in the form of a rotational element, the frontal joint mechanism will only have one DOF providing rotational displacement in the coronal plane of the distal support element with respect to the proximal support element. However, if the provided displacement element is a compliant element, then the frontal joint mechanism will either have one DOF as described above, or two DOFs as per the illustrative embodiment. In order for the frontal joint mechanism to have two DOFs, the compliant element is such as to allow providing rotational and translational deformation in the coronal plane.

[0041] The frontal joint mechanism 140 allows the distal support element 120 to move laterally and rotate freely in the coronal plane. The user can wear the orthotic device 100 while the frontal joint mechanism 140 adjusts itself to the user's leg. Therefore, the lateral reaction force and the frontal plane reaction torque are eliminated, avoiding the overstraining constraint of the knee when the user wears the orthotic device 100.

[0042] It is to be understood that although the illustrative embodiment of the frontal joint mechanism 140 has been described in the context of the knee joint, it may be applied to other joints as well. Furthermore, the use of the specific design of the orthotic device 100 is used for illustrative purposes only and it is to be understood that the frontal joint mechanism 140 may be used with other types of orthotic devices as well, for example a passive orthotic device wherein the compensating joint 130 is a passive joint component instead of an active one. Moreover, although the illustrative embodiment of the frontal joint mechanism 140 has been described by way of a two DOFs joint mechanism, it is to be understood that the frontal joint mechanism 140 may be provided with a different number of

2285375.1 DOFs (i.e. one DOF or three or more DOFs). For example, the frontal joint mechanism 140 may be provided with a single DOF, the design of which may include joint 141 but omit joint 142. It is to be further understood that the frontal joint mechanism 140 may alternatively be provided between the compensating joint 130 and the proximal support element 110.

[0043] Although the present disclosure has been described by way of particular non-limiting illustrative embodiments and examples thereof, it should be noted that it will be apparent to persons skilled in the art that modifications may be applied to the present particular embodiment without departing from the scope of the present disclosure.

2285375.1

Claims

1. A frontal joint mechanism to be coupled to an orthotic device having a distal and a proximal support elements linked together by a joint component, comprising:

a first displacement element connected to the joint component;

a rigid link connecting the first and the second displacement elements;

wherein the combination of the first and second displacement elements provides rotational and translational displacements in the coronal plane of the distal support element with respect to the proximal support element of the orthotic device.

2. A frontal joint mechanism in accordance with claim 1 , wherein the first and second displacement elements are rotational elements and wherein the frontal joint mechanism is oriented in such a way that the axes of revolution of the first and second rotational elements are parallel to the antero-posterior axis of the orthotic device, forming a plane parallel to the sagittal plane.

3. A frontal joint mechanism in accordance with either of claims 1 or 2, wherein the first displacement element allows rotational displacement in the coronal plane.

4. A frontal joint mechanism in accordance with either of claims 1 or 2, wherein the second displacement element allows rotational displacement in the coronal plane.

5. A frontal joint mechanism in accordance with any of claims 1 to 4, wherein the combination of the first and the second displacement elements allows translational displacement in the coronal plane.

2285375.1

6. A frontal joint mechanism in accordance with any of claims 1 to 5, wherein at least one of the first and second displacement elements is actuated.

7. A frontal joint mechanism in accordance with claim 1 , wherein at least one of the first and second displacement elements is a compliant element.

8. A frontal joint mechanism in accordance with claim 7, wherein the compliant element allows a displacement in the coronal plane selected from the group consisting of a rotational displacement, a translational displacement and a combination thereof.

9. A frontal joint mechanism to be coupled to an orthotic device having a distal and a proximal support elements linked together by a joint component, comprising:

a displacement element connected to the joint component and to the distal or to the proximal support element;

wherein the displacement element provides displacement in the coronal plane of the distal support element with respect to the proximal support element of the orthotic device.

10. A frontal joint mechanism in accordance with claim 9, wherein the displacement in the coronal plane is selected from the group consisting of a rotational displacement, a translational displacement and a combination thereof.

11. A frontal joint mechanism in accordance with claim 9, wherein the displacement element is a rotational element and wherein the frontal joint mechanism is oriented in such a way that the axis of revolution of the rotational element is parallel to the antero-posterior axis of the orthotic device.

12. A frontal joint mechanism in accordance with claim 11 , wherein the displacement element allows rotational displacement in the coronal plane.

13. A frontal joint mechanism in accordance with any of claims 10 to 12, wherein the displacement elements actuated.

2285375.1

14. A frontal joint mechanism in accordance with claim 10, wherein the displacement element is a compliant element.

15. A frontal joint mechanism in accordance with claim 14, wherein the compliant element allows a displacement in the coronal plane selected from the group consisting of a rotational displacement, a translational displacement and a combination thereof.

16. A frontal joint mechanism in accordance with any of claims 1 to 15, wherein the joint component is an active compensating joint providing torque between the proximal and the distal support elements.

17. A frontal joint mechanism in accordance with any of claims 1 to 15, wherein the joint component is a passive joint.

2285375.1