Field of the invention

The present invention belongs to the field of medicine and medical accessories, more precisely to the field of orthopaedic devices for non-surgical treatment of bones and joints. The invention relates to a medical accessory for replacing lost or diminished function of a muscle, which enables flexion or extension of an extremity in a joint.

Background of the invention and the technical problem

In anatomy, movement or the process of movement is an expression that includes movement of organs, joints, extremities and particular parts of a human body. The terminology of movement depends on the direction with regards to the anatomical position of joints. In general, flexion and extension are examples of angle movement, wherein two axes of joints are moved closer (flexion, bending) or moved apart (extension), thereby changing the angle between two body parts. Rotational movement for example is carried out in the shoulder joint and can be inner or external. Body movement is enabled with a muscle tissue, which is in human body generally divided into skeletal muscles, smooth muscles and the heart muscle, wherein the skeletal muscles are those which are through tendons attached to bones and are responsible for movement of bones and consequently body parts. At the same time, skeletal muscles ensure the upright posture.

Muscles are commonly found in pairs, wherein one is an antagonist and the other is an agonist, wherein agonists cause movement and antagonists limit movement. Agonist is a muscle that is contracted (shortened) in an observed move, while the antagonist is a muscle that is relaxed (elongated) in the same observed move and produces the opposite movement with regards to the agonist. An example of an antagonistic pair are biceps and triceps muscles. The two-headed upper arm muscle or biceps can be found in the front side of the upper arm and the musculocutaneous nerve (C5 and C6) innervates the biceps brachii. The latter is the flexor of the elbow joint and is by strength also the main supinator of the forearm. The three-headed upper arm muscle or triceps is a muscle that has three heads and ensures extension in the elbow. It is innerved by a radial nerve (C7 to C8). For flexion of the arm, the triceps is relaxed and the biceps is contracted in order to lift the forearm.

In case one of the nerves or parts of the muscle is injured, function of the muscle is lost, thus meaning that a person is not able to bend or extend an extremity on his/her own, for example in case of biceps and triceps muscle loss, a person is not able to bend the arm in the elbow. This means a limited mobility and lost of an ability to perform everyday movements. As the muscle function is lost, it is not possible to restore its function with usual physiotherapy devices. The technical problem, solved by the present invention, is thus construction of a medical accessory for replacing a lost muscle function, which enables flexion or extension of an extremity in a joint, wherein the accessory has to be arranged to perform a movement that a person cannot perform using muscles. The accessory has to be used in a simple manner, wherein it has to ensure reliable flexion or extension of an extremity, for example of the arm in the elbow.

State of the art

In the field of medicine, kinesiology and physiotherapy several different accessories intended to improve muscle condition and their function in flexion and extension of extremities are known. However, said accessories are entirely arranged to improve muscle power or restoration of muscle function after a prolonged immobilization due to injury treatment. Such devices are not suitable for persons with nerve injury, as they cannot restore lost muscle function. Examples of such accessories are described in the webpage of a manufacturer Dynasplint, as well as in patent applications US 4485808, US 4508111 , US 4538600 and US4947835.

Document US 4370977 discloses an improved splint for a knee or an elbow. The splint for a knee comprises attachment means for the thigh and calf, identical side parts with a hinge, that allows a pre-defined movement in the knee. The torsion spring can be used for inhibition of the quadriceps or for setting the tension during rehabilitation exercises. The torsion spring can be equipped with a special screw, with which the knee can be immobilized, thus disabling flexion and extension. The splint for the elbow operates in a similar way as the knee splint, wherein the hinge enables movement in the elbow and the spring inhibits the biceps or ensures the required tension during rehabilitation exercises. The described spring does not allow replacement of a muscle function, for example, it does not ensure flexion or extension of an arm in the elbow on its own.

Patent application JP2008272312 describes a splint for a knee, which helps in improving leg power. It comprises a support for the upper part of the leg, a second support for the lower part of the leg, a pair of torsion springs for connecting both supports and suitable attachments means. When the knee is bent and the weight is transferred to the support for the upper part of the leg, elastic energy is stored in torsion springs and returns via the back part for supporting the thigh and the back part for supporting the calf. Consequently, during running or a similar activity the elastic energy is used for pushing the thigh from behind, which improves muscle power.

Patent application JP2009279130 is the only among the mentioned documents that relates to use in flexion and extension of an extremity in the elbow, knee or wrist, wherein the movement is allowed by an air cylinder installed on a support for supporting the upper bone above the joint and on a second support for the lower bone below the joint. This solution differs from the present invention in its constructional design. Description of the solution to the technical problem

The essence of the medical accessory according to the invention is in that for replacement of lost or diminished muscle function, which allows flexion or extension of an extremity in a joint, a torsion spring is used, said spring being suitably shaped and/or pre-tensed, so that:

- In case of missing function of an active muscle (agonist) for flexion, the extension of the extremity is ensured by the tension of the torsion spring, in which energy is stored, the said stored energy being released upon relaxation of the antagonist and thereby automatically flexing the extremity and thus replacing agonist function; or

- In case of missing function of antagonist muscle for extension of an extremity, flexion of the extremity causes the tension to be stored in the torsion spring, which upon relaxation of the agonist automatically extends the extremity and thus replaces the antagonist function.

In case the accessory is arranged to enable flexion, the torsion spring is shaped so that the legs of the spring are pointing in the same direction or the angle between them is around 90° or the angle is up to around 135°. In case the accessory is arranged to enable extension, the torsion spring is shaped so that the legs of the spring are pointing in different (opposite directions) and are basically horizontal (in the same axis).

The medical accessory may be adapted for elbow, knee, wrist or any other joint that needs a working antagonistic pair of muscles for its movement.

Preferably the medical accessory is designed as an elbow splint, which comprises at least:

- an upper cuff for installation on an upper arm of a person;

- a lower cuff for installation on a forearm,

- the torsion spring, which connects: o at least one bottom support rod on the other side attached into the upper cuff; and o at least one upper support rod on the other side attached into the lower cuff; wherein one leg of the torsion spring is attached to the upper support rod, while the second leg of the torsion spring is attached to the bottom support rod.

The torsion spring may be made from any suitable material, preferably from a stainless wire for springs, wherein its R _mr 5 Nmm/° or more. The said value represents the torque needed to bend or move the spring for one degree. Preferably, the Rmr is higher than 10 Nmm/°, so that the return movement can be achieved in an adult person. Depending on the selected Rmr of the spring, the accessory according to the invention can be adapted with regards to needs and physical characteristics of the user, wherein children and those with lower weight or muscle strength have the accessory with a spring having a lower Rmr, while adults and stronger as well as heavier people have the accessory with a spring having a higher Rmr.

The torsion spring is activated by extending or flexion of the arm, so that energy is stored in the spring, said energy allowing the return movement of the arm. Muscle function replaced by the accessory is defined by the shape of the torsion spring as described above. Two torsion springs may be provided, one on each side of the elbow, wherein consequently two supporting rods (left and right) are provided for the upper arm and the forearm, respectively.

In addition, the accessory may have two springs, each on one side of the elbow. Optionally, it may also be provided with a movement limiter, which prevents extension or flexion in pre-defined angles. The spring may be provided with a lock, which allows activation or deactivation of the spring function. The lock may be designed in any suitable way, while some exemplary and preferred embodiments are described below.

In the first possible embodiment of the lock the lower leg of the spring, which is attached to the bottom support rod, the spring leg is connected to the support rod in a flexible manner using a blocking element, which can be rigidly connected to the support rod or removed from the latter, so that it cannot be moved together with the spring, thereby preventing flexion of an arm. The element can be controlled with a suitable trigger/button and is arranged to either press onto the element to ensure connection or the leg relaxes the spring and removes it from the support rod.

In the second embodiment of the lock, instead of the blocking element, a pair of strong magnets is used, wherein one is installed on a leg of the spring, and the other is installed on the lower supporting rod. With the button on the exterior of the accessory, a distancing element shaped as an elongated element with increasing height can be moved, the said distancing element arranged to be with its higher part inserted between the two magnets, thereby interrupting the connection between the spring and the lower supporting rod. When a connection between the spring and the bottom support rod is established, the distancing element is with its flatter part between the magnets, which does not affect the attraction between the magnets.

The cuffs may be any suitable cuffs, while their attachment may be achieved using tapes with hooks and loops, with buttons or any other ways for installation of medical accessories onto a part of a human body. The cuffs for attaching the accessory may be several. Preferably, the accessory also extends over the shoulder joint, wherein in the shoulder area the accessory is shaped in any known suitable manner for shoulder braces or similar accessories, as such shape improves arm stability.

Supporting rods may be uniform or telescopic in order to adjust the accessory to arms of different lengths. Preferably the supporting rods are made from plastic, aluminium, fiberglass, carbon fibres or any other materials suitable for skin contact. Said rods are attached to the torsion spring using s pomocjo razdruzjive zveze, kot je pritrditev s pomocjo posebno oblikovanega pritrdilnega elementa kot je opisan zgoraj za variante z zaklepom ali s pomocjo varjenja ali katerekoli druge nerazdruzljive zveze, ce pripomocek nima zaklepa in se delovanja vzmeti ne more prekiniti. Vzmet je lahko pritrjena tudi s pomocjo vijaka z matico, pri cemer ima vijak luknjo, skozi katero se napelje krak vzmeti. Podporne palice imajo lahko katerikoli obliko prereza (lahko so okrogle ali ploscate), pri cemer se vstavijo v ustrezna vpetja ali zepe v pritrdilnih mansetah pripomocka po izumu. The described solution for the elbow may also be useful for making the medical accessory suitable for flexion or extension of a leg in the knee joint or in the ankle, wherein such knee accessory comprises at least the following:

- an upper cuff for attachment to the thigh,

- a lower cuff for attachment to the calf,

- a torsion spring, which connects: o at least one bottom support rod on the other side attached into the upper cuff; and o at least one upper support rod on the other side attached into the lower cuff; wherein one leg of the torsion spring is attached to the upper support rod, while the second leg of the torsion spring is attached to the bottom support rod.

The torsion spring may be made from any suitable material, preferably from stainless wire for springs, R _mr is at least 15 Nmm/°, so that return movement may be achieved. The torsion springs may be two, one of each side of the knee.

The torsion spring is activated with flexion or extension of the leg, thereby storing an energy, which ensures the return movement of the leg. In case the accessory is arranged for flexion, the torsion spring is shaped in such a manner that the legs of the spring are pointing in the same direction or the angle between them is around the right angle or an angle up to approximately 135°. In case the accessory is arranged for flexion, the torsion spring is shaped in such a manner that the legs of the spring are pointing into opposite directions, so that they are basically parallel or in the same axis, respectively.

Use of the medical accessory according to the invention is suitable for persons that have lost function of one of the muscles in an antagonistic pair due to a disease or injury, for example:

- Loss of biceps function due to damaged nerve C5 and/or C6,

- Loss of triceps function due to damaged nerve C7 and/or C8,

- Loss of function of one of the muscles in any antagonistic pair.

During use of the accessory according to the invention in case of damaged nerve C5 and/or C6, upon extension of an arm energy is stored in the torsion spring, which is released upon relaxation of the triceps muscle, thereby moving the arm into flexed position.

Furthermore, the described accessory may be upgraded in order to replace any other missing or diminished muscle function. In case of the elbow accessory, limited or diminished function of muscles that enable pronation or supination of the arm can be replaced. Pronation is a move in which the palm of an arm is turned downwards, while supination is a move in which the palm is turned upwards, if the arm is extended before the body. For this upgrade the accessory has at least the following components:

- An upper cuff for installation on the upper arm,

- A lower cuff for installation on the forearm,

- A torsion spring, which connects: o an upper support rod, on the other end attached to the upper cuff, and o a bottom support rod, on the other end attached to the lower cuff, wherein one leg of the torsion spring is attached to the upper support rod, while the other leg of the torsion spring is attached to the bottom support rod,

- an elbow hinge with the said torsion spring,

- at least one element for return movement, preferably an elastic band, one end of which being arranged for installation around the thumb, and

- at least two stabilization rings installed on each of the two bottom support rods, wherein the ring closer to the wrist has a suitably shaped opening for installation of the second end of the elastic band.

For ensuring pronation (the user may on his own turn the palm upwards, but not downwards), the elastic band is preferably installed onto a guide on the outer side of the forearm and is led along the wrist on the bottom side of the palm to the thumb.

For ensuring supination (the user can turn the palm downwards on his own, but not upwards), the elastic band is preferably installed on the inner guide on the forearm and is led along the wrist on the upper side of the palm to the thumb.

The elastic band can be additionally installed via a suitable cylinder or a suitable element, which is mounted on the opposite side of the ring from the elastic band, as this reduces point loads of the elastic band. For more equal distribution of forces, the elastic band is preferably affixed to the thumb using a glove such as a cycling glove. This positively affects blood circulation in the thumb during prolonged active use of the accessory, which can be hampered in the embodiment without the glove.

Instead of the rubber band used for the return movement a suitably shaped bearing shaped as a ring placed around the arm can be used, said ring-shaped bearing having in its interior suitable springs or weights, which return the arm into the required position. One possible embodiment of the bearing is preferably oiled cylinder bearing, which instead of the free rotation always gravitates into a stable state. A complete rotation is impossible with such a bearing. The cylinder bearing has in its interior a suitable number of free leaf springs, two cylinders are attached, one on the inner and the second on the outer circumference (rim). In the embodiment with the bearing, the inner ring of the bearing has to rest against the arm without sliding, while the embodiment without bearings the rings may slide along the skin of the arm.

Said rings are preferably two-part rings or can be opened, respectively, so that the arm can be placed in the accessory, wherein the rings preferably do not touch the arm or are only in a slight touch. It is important that the rings do not squeeze the arm. The rings may be installed on the support rods in any known manner, preferably they are mounted using ears or screwing.

The upper cuff may be arranged to cover the shoulder as some of the currently known accessories, which are installed over one arm to the second armpit around the body. This part of the cuff may be made from any suitable materials and is preferably installed using Velcro tapes with hooks and loops.

The described upgrade of the medical accessory according to the invention, which may replace more than one missing muscle function, may be made in different combinations, namely the accessory may enable replacing:

- flexion,

- extension,

- flexion and pronation, - flexion and supination,

- extension and pronation, or

- extension and supination.

During development of the invention, it has been observed that the medical accessory is also suitable for persons with extremely diminished muscle function, wherein nerves are not hampered, but instead the muscle tissue is so weak that flexion or extension cannot be performed.

The medical accessory for replacing lost or diminished function of a muscle, which enables flexion or extension of an extremity in a joint according to the invention will be described in further detail based on exemplary embodiments and figures, which show:

Figure 1a Shape of the torsion spring for the accessory for flexion Figure 1b Shape of the torsion spring for the accessory for extension Figure 1c A possible embodiment of the shape of the torsion spring shown in figures 1a and 1b

Figure 2 A schematic view of the working principle of the medical accessory according to the invention

Figure 3 An embodiment of the medical accessory according to the invention for an elbow

Figure 4 An embodiment of the medical accessory according to the invention for a knee

Figure 5 An embodiment of the medical accessory according to the invention for an elbow, which also allows replacement of muscle function for supination

Figure 6 An embodiment of the medical accessory according to the invention for an elbow, which also allows replacement of muscle function for pronation The medical accessory according to the invention may be adapted for elbow, knee, wrist or any other joint that needs a working antagonistic pair of muscles for its movement. Preferably the medical accessory is designed as a splint for an elbow comprising at least:

- an upper cuff for installation on an upper arm of a person;

- a lower cuff for installation on a forearm,

- the torsion spring, which connects: o at least one bottom support rod on the other side attached into the upper cuff; and o at least one upper support rod on the other side attached into the lower cuff; wherein one leg of the torsion spring is attached to the upper support rod, while the second leg of the torsion spring is attached to the bottom support rod.

The torsion spring is activated by extension or flexion of the arm, thus storing an energy that enables the return stroke (movement) of the arm. The muscle function, which is replaced with the accessory, is defined with the choice of the torsion spring shape. In case the accessory is arranged for flexion the torsion spring is shaped as shown in figure 1a, so that the legs of the spring are pointing to the same direction or the angle between them is approximately 90° or up to 135°. In case the accessory is arranged for extension, the torsion spring is shaped as shown in figure 1b, so that the legs of the spring are pointing into opposite directions and practically horizontal (in the same axis). Figure 1c shows a preferred embodiment of the torsion spring, wherein both legs have a right angle between them.

Figure 2 shows a schematic view of the operation principle of the medical accessory according to the invention. The accessory has a suitably shaped torsion spring, which ensures one of the following functions: a) In case of missing function of an active muscle (agonist) for flexion, the extension of the extremity is ensured by the tension of the torsion spring, in which energy is stored, the said stored energy being released upon relaxation of the antagonist and thereby automatically flexing the extremity and thus replacing agonist function; or b) In case of missing function of antagonist muscle for extension of an extremity, flexion of the extremity causes the tension to be stored in the torsion spring, which upon relaxation of the agonist automatically extends the extremity and thus replaces the antagonist function.

In case of a) the torsion spring is shaped so that the legs of the spring are pointing in the same direction or the angle between them is around 90° or the angle is up to around 135°. In case the accessory is arranged to enable extension. The user extends the arm, with which he uses triceps to overcome the force of the spring. When the user wishes to bend the arm, the triceps is relaxed, which means that the force of the spring is higher and thus moves the lower part of the arm towards the upper. In case the spring is equipped with a limiter, the flexion ends at the angle, which has been predefined with the limiter.

In case the accessory is arranged for extension (b) the torsion spring is shaped so that the legs of the spring are pointing in different (opposite directions) and are basically horizontal (in the same axis). The user bends the arm in the elbow and thos overcomes the force of the spring, wherein upon relaxation of the biceps, the force of the spring is higher and leads to extension of the arm. In case the spring is equipped with a limiter, the extension of the arm ends at the angle, which has been predefined with the limiter.

Figure 3 shows a possible embodiment of the medical accessory 1 for an elbow, wherein the accessory 1 comprises:

- an upper cuff 1 a for installation on an upper arm of a person;

- a lower cuff 1 b for installation on a forearm,

- the torsion spring 3, which connects: o at least one bottom support rod 2a on the other side attached into the upper cuff 1a; and o at least one upper support rod 2b on the other side attached into the lower cuff 1 b;

- wherein one leg 3a of the torsion spring 3 is attached to the upper support rod 2a, while the second leg 3b of the torsion spring 3 is attached to the bottom support rod 2b.

Figure 4 shows a possible embodiment of the medical accessory 21 for a knee, wherein the accessory 21 comprises:

- an upper cuff 21a for installation onto a thigh,

- a lower cuff 21 b for installation on calf,

- a torsion spring 23, which connects: o the upper support rod 22a on the other end attached to the upper cuff 21a, and o the bottom support rod 22b on the other side attached to the lower cuff 21b, wherein one leg 23a of the torsion spring 23 is attached to the upper support rod 22a, while the second leg 23b of the torsion spring 23 is attached to the lower support rod 22b.

Figure 5 shows a possible embodiment of the medical accessory 10 for an elbow, which also enables replacement of muscle function for supination, wherein the accessory 10 comprises the following components:

- an upper cuff 10a for installation on the upper arm,

- a lower cuff 10b for installation on the forearm,

- a torsion spring 13, which connects: o the upper support rod 12a on the other end attached to the upper cuff 10a, and o the bottom support rod 12b on the other side attached to the lower cuff 10b, wherein one leg 13a of the torsion spring 13 is attached to the upper support rod 12a, while the second leg 13b of the torsion spring 13 is attached to the lower support rod 12b; - at least two rings 14, which do not squeeze the arm and allow its movement,

- and an elastic band 15, wherein the elastic band is preferably installed on an inner guide on the forearm and is led along the wrist on the upper side of the palm to the thumb.

Figure 6 shows a possible embodiment of the medical accessory 100 for an elbow, which also enables replacement of muscle function for pronation, wherein the accessory 100 comprises the following components:

- an upper cuff 100a for installation on the upper arm,

- a lower cuff 100b for installation on the forearm,

- a torsion spring 103, which connects: o the upper support rod 102a on the other end attached to the upper cuff 100a, and o the bottom support rod 102b on the other side attached to the lower cuff 100b, wherein one leg 103a of the torsion spring 103 is attached to the upper support rod 102a, while the second leg 103b of the torsion spring 103 is attached to the lower support rod 102b;

- at least two rings 104, which do not squeeze the arm and allow its movement,

- and an elastic band 105, wherein the elastic band is preferably installed on an guide on the outer side of the forearm and is led along the wrist on the bottom side of the palm to the thumb.