FIELD OF THE INVENTION:

This invention relates to the field of biomedical engineering.

Particularly, this invention relates to a stance controlled knee-ankle foot orthosis.

BACKGROUND OF THE INVENTION:

Poliomyelitis, often called polio or infantile paralysis, is an infectious disease caused by the poliovirus. In about 0.5 percent of cases there is muscle weakness resulting in an inability to move.

Knee ankle foot orthoses (KAFO) are prescribed to patients whose knee joints can’t function normally for reasons ranging from injuries to disease so as to support the knee joint. Current KAFO designs lock knee joints in both stance and swing phase resulting in unnatural gait like circumduction causing fatigue. Additionally, imported KAFOs are expensive and an orthosis resulting in natural gait can be useful.

According to Artificial Limbs Manufacturing Corporation of India (ALMICO) year-wise annual report 2017-2018, orthotic lower kits and components had production of 23,948 and 31 ,293 (In no’s) over the years 2016-2017 and 2017- 2018 respectively with % increase over 201-2017 as 30.67%.

Statistical data from Jaipur Foot show that from 1991 to 31/03/2016 they have distributed a total of 409944 calipers to disabled persons. Patients are prescribed an orthosis to take away the load on the knees exerted during the walking. This may be due to reasons ranging from disease to injury.

Prior art designs do not have an actuation mechanism that uses or understands human weight.

Prior art devices, such as knee ankle foot orthoses, use a droplock mechanism to lock and unlock the device which leads to circumduction and a tiring gait. This leads to an inefficient gait which leads in more energy spent during walking electric and electronic versions are heavy, bulky, and expensive.

One prior art which was a Stance Controlled Knee Ankle Foot Orthosis (SCKAFO) locks (heel strike) and unlocks (heel off) according to the gait cycle thus providing a human like gait. (SCKAFO) which use electric and electronic components are expensive and out of reach for a vast strata of society apart from being bulky because they need a battery.

There is a need for an orthoses which solves the above-mentioned problems.

OBJECTS OF THE INVENTION:

An object of the invention is to improve gait of persons with weak knee joints or polio.

Another object of the invention is to provide persons with weak knee joints in walking with a natural gait. Yet another object of the invention is to provide a stance-controlled knee ankle foot orthosis for weak knee patients.

Yet another object of the invention is to provide an orthosis which assists in achieving a normal gait cycle.

SUMMARY OF THE INVENTION:

According to this invention, there is provided a stance controlled knee-ankle foot orthosis, comprising:

a thigh assembly configured to provide thigh support;

a knee assembly configured to provide knee support;

a shank assembly configured to provide shank support;

a foot assembly configured to provide foot support;

characterised in that,

said foot assembly comprising a base plate on which a foot rests, said base plate comprising a heel pressure plate configured to senses pressure from heel of a wearer of said orthosis in a stance phase of a gait cycle and to sense lack of pressure in a swing phase of the gait cycle or in a squatting phase;

an actuating assembly comprising:

o a ratchet which extends, operatively downwards, from lateral edges of said thigh assembly;

o a pawl which extends, operatively upwards, from lateral edges of said shank assembly;

o said pawl and said ratchet form the core actuator assembly and engage with each other during said stance phase and disengage with each other during said swing phase or squatting phase; a normally compressed resilient element at the heel end of said base plate configured such that upon application of force on said base plate, said normally compressed resilient element stays compressed and upon removal of force from said base plate, said normally compressed resilient element decompresses;

a normally stretched resilient element which borrows support, at its one end from said thigh assembly and is engaged, at its other end, with a non-engaging end of said pawl, said normally stretched resilient element being configured to space apart the engaging end of said pawl from said ratchet; and

a connecting wire being lodged, at its first end, with said base plate near said normally compressed resilient element and being lodged, at its second end with an engaging end of said pawl.

Typically, said normally compressed resilient element is a compression spring.

Typically, said normally stretched resilient element is a tension spring.

Typically, said normally stretched resilient element borrows support, at its one end from said second actuating member.

Typically, said the actuating assembly is offset from a knee-thigh-calf axis of a person.

Typically, a first actuating member, which borrows support from said thigh assembly, comprises said ratchet which is an operative lower end part- circumferential toothed end and said ratchet being angled away from the axis towards the rear of a person, thereby causing the offset. Typically, a second actuating member, which borrows support from said shank assembly, locates a pawl on it, which second actuating member being angled away from the axis towards the rear of a person such that the engaging end of the pawl is offset and engage-able with the teeth of the pawl.

Typically, said ratchet comprises teeth covering more than half of its circumferential edge; thereby allowing a full uninhibited squatting position for a wearer of said orthosis.

Typically, said orthosis comprises a hinge provided with its first end driving support from said foot assembly and with its second end providing an anchor for an auxiliary connecting wire which runs from said hinge to said ratchet.

Typically, in a walking gait cycle, in stance phase, force is applicable via a heel of a person to said base plate which keeps said normally compressed resilient element compressed, said connecting wire, in its normal operative condition, and said normally stretched resilient element, in its normal resting condition, and does not space apart said pawl from said ratchet and keeps it engaged; thereby, locking said knee assembly and lending support to a user of the orthosis to stand.

Typically, in a walking gait cycle, in swing phase, force, from a heel, is lifted and, hence, is not applicable to the base plate which decompresses said normally compressed resilient element, the connecting wire acts due to this to space apart said pawl from said ratchet and keeps it disengaged, said normally stretched resilient element being compressed from its normal tensioned state; thereby, unlocking said knee joint and allowing a user of the orthosis to angularly displace the shank portion about the knee assembly allowing a user to walk / run / cycle. Typically, for every cycle of a walking gait, there is a locking step (for stance phase) and an unlocking step (for swing phase).

Typically, said thigh assembly comprising a thigh socket which is a contoured plate / curved plate coupled at its one lateral side / lateral end to a first lateral elongate member and at its other lateral side / lateral end to a second lateral elongate member, said first lateral elongate member connecting said thigh assembly to a first actuating member of a knee part and said second lateral elongate member connecting said thigh assembly to a third actuating member of a knee part.

Typically, said knee assembly comprising said first actuating member coupled to a second actuating member and said third actuating member coupled to a fourth actuating member, each of said coupling being formed by a corresponding ratchet and pawl mechanism

Typically, said shank assembly comprising a shank socket being embracing / contoured plate coupled at its one lateral end to a third lateral elongate member and at its other lateral end to a fourth lateral elongate member.

Typically, the second actuating member is connected to the third elongate member by means of fifth elongate member.

Typically, the second actuating member is connected to the fourth elongate member by means of a sixth elongate member, said shank socket joined to a footplate. Typically, said foot assembly comprising a foot enclosing assembly with a resilient element configured to be located at an operative top edge of said foot enclosing assembly and is in correspondence / correlative to an ankle of a user wearing said orthosis to provide angular displacement of an operative top edge of said foot enclosing component with respect to an operative bottom edge of said shank socket.

Typically, foot enclosing component’s said resilient element being a curvilinear element.

Typically, said thigh assembly comprises a thigh socket which is a contoured plate / curved plate coupled at its one lateral side / lateral end to a first lateral elongate member and at its other lateral side / lateral end to a second lateral elongate member, characterised in that, said elongate members running down the free lateral ends of said curved plate and their operative lower ends being longer than the lateral sides of the thigh socket.

Typically, fastening elements couples:

- said first elongate member to said thigh socket;

- said first lateral elongate member to actuating members; and

- said second lateral elongate member to actuating members.

Typically, said first actuating member comprising a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a second actuating member. Typically, said first actuating member comprises a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a second actuating member, characterised in that, said pawl which engages with said circumferentially toothed end of said first actuating member, said pawl resting on a protrusion which is a part of said second actuating member and is free to angularly displace about said protrusion.

Typically, said first actuating member comprises a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a second actuating member, characterised in that, at least one resilient element is provided which is connected, at its one end, to said second actuating member and, at its other end, to said pawl.

Typically, said first actuating member comprises a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a second actuating member, characterised in that, at least one resilient element is provided to join said pawl and an outer force transmitter [seventh elongate member].

Typically, said first actuating member comprises a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a second actuating member, characterised in that, said second actuating member being joined to a sixth elongate member. Typically, said third actuating member comprises a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a fourth actuating member.

Typically, said third actuating member comprises a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a fourth actuating member, characterised in that, said pawl which engages with said circumferentially toothed end of said third actuating member, said pawl resting on a protrusion which is a part of said fourth actuating member and is free to angularly displace about said protrusion.

Typically, said third actuating member comprises a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a fourth actuating member, characterised in that, at least one resilient element is provided which is connected, at its one end, to the fourth actuating member and, at its other end, to the pawl.

Typically, said third actuating member comprises a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a fourth actuating member, characterised in that, at least one resilient element is provided to join said pawl to an outer force transmitter [eighth elongate member]. Typically, said third actuating member comprises a ratchet wheel (having a circumferential toothed end) at its operative lower end, said ratchet wheel being configured to engage with a pawl at an operative upper end of a fourth actuating member, characterised in that, said fourth actuating member being joined to a fifth elongate member.

Typically, said first actuating member is joined by a pin joint to said second actuating member and is free to angularly displace about said pin that is formed by joining a knee pin male and a knee pin female.

Typically, said third actuating member is joined by a pin joint to said fourth actuating member and is free to angularly displace about said pin that is formed by joining a knee pin male and a knee pin female.

Typically, a fifth elongate member and a sixth elongate member are rigidly joined to said shank socket.

Typically, said shank socket being joined to a footplate by a pin that consists of two components; a male ankle pin and a female ankle pin.

Typically, an outer lever and an inner lever are mounted over said foot enclosing component, each of said levers configured to transmit corresponding force, from a corresponding seventh elongate member and a corresponding eighth elongate member, to corresponding resilient components.

Typically, an outer lever is mounted on a protrusion on said foot plate and being free to angularly displace about said protrusion. Typically, an inner lever is mounted on a protrusion on said foot plate and being free to angularly displace about said protrusion.

Typically, an outer lever and an inner lever are mounted over said foot enclosing component, each of said levers configured to transmit corresponding force, from a corresponding seventh elongate member and a corresponding eighth elongate member, to corresponding flexible components, characterised in that, said resilient element being joined to said outer lever and said seventh elongate member being mounted on said protrusion on said outer lever.

Typically, an outer lever and an inner lever are mounted over said foot enclosing component, each of said levers configured to transmit corresponding force, from a corresponding seventh elongate member and a corresponding eighth elongate member, to corresponding flexible components, characterised in that, said resilient element being joined to said inner lever and said eighth elongate member being mounted on said protrusion on said inner lever.

Typically, said seventh elongate member joins inner lever and said second actuating member on an operative right side.

Typically, said eighth elongate member joins outer lever and said first actuating member on an operative left side.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

The invention will now be described in relation to the accompanying drawings, in which: Figure 1 (assembly) is a complete view of the stance controlled knee-ankle orthosis showing all the components assembled;

Figure 1(a) shows an upper part of the orthosis which consists of a socket and supporting strips, this upper part being the thigh part (1) / thigh assembly (1);

Figure 1 (b) an exploded view of the upper part of the orthosis assembly, this upper part being the thigh part (1) / thigh assembly (1);

Figure 2(a) shows a knee part (2) / knee assembly (2) of the orthosis;

Figure 2(b) shows an exploded view of the knee part (2) / knee assembly (2) of the orthosis;

Figure 3 (a) shows an assembled shank part (3) / shank assembly (3) of the orthosis;

Figure 3 (b) shows the exploded view of the shank part (3) / shank assembly (3) of the orthosis;

Figure 4 shows an exploded view of the foot part (4) / foot assembly (4) of the orthosis;

Figure 5a illustrates a side view of the orthosis of this invention, in one of its embodiments;

Figure 5b illustrates an enlarged version of the actuator assembly of the orthosis of Figure 5 a;

Figure 6a illustrates a side view of the orthosis of this invention, in one of its alternative embodiments; and

Figure 6b illustrates an enlarged version of the actuator assembly of the orthosis of Figure 6a.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

According to this invention, there is provided a stance controlled knee-ankle foot orthosis. Figure 1 (assembly) is a complete view of the stance controlled knee-ankle orthosis showing all the components assembled.

In at least an embodiment, this orthosis is comprised, substantially, of four main parts:

1) a thigh part (1) / thigh assembly (1);

2) a knee part (2) / knee assembly (2);

3) a shank part (3) / shank assembly (3); and

4) a foot part (4) / foot assembly (4).

Figure 1(a) shows an upper part of the orthosis which consists of a socket and supporting strips, this upper part being the thigh part (1) / thigh assembly (1). Figure 1(b) an exploded view of the upper part of the assembly, this upper part being the thigh part (1) / thigh assembly (1).

In at least an embodiment of the thigh part (1) / thigh assembly (1), a thigh socket (la) is an embracing plate / contoured plate / curved plate coupled at its one lateral side / lateral end to a first lateral elongate member (lc) and at its other lateral side / lateral end to a second lateral elongate member (lb). These elongate members (lc, lb) may run down the free lateral ends of the curved plate and their operative lower ends may be longer than the lateral sides of the thigh socket (la). Component (Id) resembles fastening elements which fastens / joins the first elongate member (lc) to the thigh socket (la), joins the second elongate member (lb) to the thigh socket (la), joins the first lateral elongate member (lc) to actuating members (2b), and joins the second lateral elongate member (lb) to actuating members (2a). Additionally, the first lateral member (lc) connects the thigh socket (la) to a first actuating member (2a) of the knee part (lb). Similarly, the second lateral member (lb) connects the thigh socket (la) to the third actuating member (2b) of the knee part (lb).

Figure 2(a) shows a knee part (2) / knee assembly (2) of the orthosis.

Figure 2(b) shows an exploded view of the knee part (2) / knee assembly (2) of the orthosis.

In at least an embodiment of the knee part (2) / knee assembly (2), a left side of the orthosis is disclosed, in that, a first actuating member (2a) with a circumferentially toothed end is connected to a second actuating member (2d) by a pin with a stub (2g) and corresponding lock (2h). A pawl (2e) which engages with the circumferentially toothed end i.e. a ratchet (2i) of the first actuating member (2a) rests on a cylindrical protrusion which is a part of the second actuating member (2d). At least one resilient element (2f) is provided which is connected, at its one end, to the second actuating member (2d) and, at its other end, to the pawl (2e).

In at least an embodiment of the knee part (2) / knee assembly (2), a right side of the orthosis is disclosed, in that, a third actuating member (2b) with a circumferentially toothed end (2i) is connected to a fourth actuating member (2c) by a pin with a stub (2g) and corresponding lock (2h). A pawl (2e) which engages with the circumferentially toothed end i.e. a ratchet (2i) of the third actuating member (2b) rests on a cylindrical protrusion which is a part of the fourth actuating member (2c). At least one resilient element (2f) is provided which is connected, at its one end, to the fourth actuating member (2c) and, at its other end, to the pawl (2e). The knee part (2) / knee assembly (2) may also be an actuator assembly.

Typically, when the orthosis, of this invention, is worn, the knee assembly (1) correlates / positions with respect to the knee of a person wearing this orthosis.

Left toothed knee first actuating member (2a) is joined by a pin joint (2h, 2g) to left knee second actuating member (2d) and is free to angularly displace about the pin that is formed by joining two components namely, knee pin male (2g) and knee pin female (2h). The pawl (2e) is mounted over a cylindrical protrusion which is a part of first actuating member (2a) and is free to angularly displace about the protrusion. The resilient element (2f) is attached to the pawl (2e) and left knee second actuating member (2d). Another piece of the resilient element (2f) is used to join the pawl (2e) and an outer force transmitter (4e). The left knee second actuating member (2d) is joined to left below knee strip (3b) by the pin (Id).

Right toothed knee third actuating member (2b) is joined by a pin joint (2h, 2g) to right knee fourth actuating member (2c) and is free to angularly displace about the pin that is formed by joining two components namely, knee pin male (2g) and knee pin female (2h). The pawl (2e) is mounted over a cylindrical protrusion which is a part of third actuating member (2b) and is free to angularly displace about the protrusion. The resilient element (2f) is attached to the pawl (2e) and right knee fourth actuating member (2c). Another piece of the resilient element (2f) is used to join the pawl (2e) and an outer force transmitter (4e). The right knee fourth actuating member (2c) is joined to right below knee strip (3a) by the pin (Id).

Figure 3 (a) shows an assembled shank part (3) / shank assembly (3) of the orthosis. Figure 3 (b) shows the exploded view of the shank part (3) / shank assembly (3) of the orthosis.

In at least an embodiment of the shank part (3) / shank assembly (3), an shank socket (3c) is an embracing / contoured plate coupled at its one lateral end to a third lateral elongate member (3f) and at its other lateral end to a fourth lateral elongate member (3g). The second actuating member (2d) is connected to the third elongate member (3f) by means of fifth elongate member (3a). Further, the second actuating member (2d) is connected to the fourth elongate member (3g) by means of a sixth elongate member (3b).

As seen in Figure 3(a) right below knee strip [fifth elongate member] (3 a) and left below knee strip [sixth elongate member] (3b) are rigidly joined to the shank socket (3c) by a pin (Id). The shank socket (3c) is joined to a footplate (4d) by a pin that consists of two components; a male ankle pin (3d) and a female ankle pin (3e)

Figure 4 shows an exploded view of the foot part (4) / foot assembly (4) of the orthosis.

In at least an embodiment of the foot part (4) / foot assembly (4), a foot enclosing component (4d) is provided. A resilient element (4a) is provided which is a curvilinear element configured to be located at the operative top edge of the foot enclosing assembly (4) and is in correspondence / correlative to an ankle of the user wearing this orthosis and plays a role in spacing apart / angular displacement (of) the operative top edge of the foot enclosing component (4d) with respect to the operative bottom edge of the shank socket (3 c). Two levers (4c) and (4b) are mounted over the component foot enclosing component (4d). A seventh elongate member (4e) and an eighth elongate member (4f) transmit force from the levers (4c) and (4b) to the flexible component (2f) and (2a).

Outer lever (4b) and inner lever (4c) are mounted on a cylindrical protrusion on the foot plate (4d) and are free to angularly displace about the protrusion. The flexible / resilient element (4a) is joined to outer lever (4b). Outer force transmitter (4e) is mounted on a protrusion on the outer lever (4b) and is free to rotate It joins outer lever (4b) and the flexible component (2f). Inner force transmitter (4c) is mounted on a protrusion on the inner lever (4c) and is free to angularly displace. Inner force transmitter (4c) joins inner lever (4c) and right teethed knee upper [second actuating member] (2b) on the right side. On the left side another piece of the inner force transmitter (4c) is, similarly, joined to the inner lever (4c) to left teethed knee upper [first actuating member] (2a).

When this assembly is worn by a human being on their legs and when the leg is in its final phase of swing, the heel part of the assembly comes in contact with the ground. Outer lever (4b) touches the ground, it angularly displaces around the protrusion and pulls the outer force transmitter (4e) which in turn exerts force over the flexible component (2f) which extends in length till a limit after which the pawl (2e) starts to angularly displace around the protrusion on left knee lower [second actuating member] (2d) and right knee lower [fourth actuating member] (2c). The pointed part of the pawl (2e) engages with the teeth on the left teethed knee upper [first actuating member] (2a) and right teethed knee upper [third actuating member] (2b). The shape and location of the teeth is designed such that the angularly displacement of the left teethed knee upper [first actuating member] (2a) with respect to left knee lower [second actuating member] (2d) in the counterclockwise direction is allowed and not in the other direction.

A brief moment later (depending on walking speed), inner lever (4c) comes in contact with the ground and angularly displaces around the protrusion and pulls the inner force transmitter (4f) which in turn exerts the force on left teethed knee upper [first actuating member] (2a) and right teethed knee upper [third actuating member] (2b) on both sides which in turn pulls the upper part of the assembly consisting of the thigh socket (la).

When the human leg leaves the ground, the outer lever (4b) and inner lever (4c) go back to their original position. The flexible component (2f) regains its original shape. The pawl (2e) on both sides disengages from the left teethed knee upper [first actuating member] (2a) and right teethed knee upper [third actuating member] (2b) and the knee joint can rotate freely.

This invention allows patients with weak knee joints in walking with a natural gait. The upper part of the mechanism consists of a socket to accommodate the thigh and metal strips to support it along with the pins used to hold them in place. The major components of the knee part of the device include a pawl and ratchet mechanism along with the springs which on activation ensure the locking and unlocking of the assembly according to the gait of the person. The shank part of the assembly consists of the socket to hold the legs and leg strips to support them. The foot part of the assembly consists of the ankle support, the two levers which actuate the member that exerts force on the springs which in turn exert force on the pawl This stance controlled knee ankle foot orthosis uses the body weight to exert on the described mechanism which locks and unlocks according to the need and thus results in a better and human like gait.

This stance controlled knee ankle foot orthosis uses human body weight and heel strike for functioning of the pawl and ratchet locking mechanism. The force transmitter helps in making the leg straight. The pawl (2e) and ratchet mechanism (2i) allows the rotation of the mechanism in one direction and not the other

Figure 5a illustrates a side view of the orthosis of this invention, in one of its embodiments.

Figure 5b illustrates an enlarged version of the actuator assembly of the orthosis of Figure 5 a.

The foot part (4) / foot assembly (4) comprises, in one of the embodiments, a base plate on which a foot rests, the base plate (51) comprising a heel pressure sensor or a heel pressure plate or a heel pressure element, in that, it senses pressure from heel of a wearer of this SCAFO. In other words, the pressure sensor / plate / element is senses pressure in stance phase of a gait cycle and activates / engages pertinent components of the actuator assembly to assist in the stance phase. In the swing phase, pressure is not sensed and this activates / engages pertinent components of the actuator assembly to assist in the swing phase. Additionally, in this stance phase, the actuator assembly engages pertinent components to allow a person to squat completely providing adequate support and locking.

In at least an embodiment, the base plate (51) is located underneath the foot part (4) / foot assembly (4). The base plate (51) comprises a normally compressed resilient element (53) at the heel end of the base plate. This normally compressed resilient element (53) is a compression spring (53). Upon exertion of force / application of force on the base plate (51), the normally compressed resilient element (53) stays compressed and upon removal of force from the base plate (51), i.e. upon lifting of heel, the normally compressed resilient element (53) decompresses / releases and actuates further corresponding members of the actuating assembly.

In at least an embodiment, the actuating assembly is comprised of:

- a ratchet (2i) which extends, operatively downwards, from lateral edges of the thigh part (1) / thigh assembly (1);

- a pawl (2e) which extends, operatively upwards, from lateral edges of the shank part (3) / shank assembly (3).

The pawl (2e) and ratchet (2i) form the core actuator assembly and engage with each other, advantageously, as discussed below.

In at least an embodiment of this invention, the actuating assembly (2i, 2e) is offset from a knee-thigh-calf axis of a person. The first actuating member (2a), which borrows support from the thigh part (1) / thigh assembly (1), comprises a ratchet (2i) which is an operative lower end part-circumferential toothed end and this ratchet (2i) is angled away from the axis towards the rear of a person. This causes the offset. The second actuating member (2d), which borrows support from the shank part (3) / shank assembly (3), locates a pawl (2e) on it, which second actuating member (2d) is angled away from the axis towards the rear of a person such that the engaging end of the pawl (2e) is offset and engage-able with the teeth of the pawl (2e). In cases where a person’s thigh is not aligned along a normal axis, this offset allows the thigh part (1) / thigh assembly (1) to be pushed forward, i.e. in line with the axis, when the actuator assembly (2i, 2e) and allows the person to assume normal / correct stance. In cases where a person’s knee is not aligned along a normal axis, this offset allows the knee part (2) / knee assembly (2) to be pushed forward, i.e. in line with the axis, when the actuator assembly (2i, 2e) and allows the person to assume normal / correct stance.

In at least an embodiment, a normally stretched resilient element (55), i.e. a tension spring, is provided on the second actuating member (2d) which borrows support, at its one end from the second actuating member (2d) and is engages at its other end with a non-engaging end of the pawl (2e). The tension spring (55), essentially, spaces apart the engaging end of the pawl (2e) from the ratchet (2i).

In at least an embodiment, a connecting wire (57) is lodged, at its first end, with the base plate (51) near the normally compressed resilient element (53) and is lodged, at its second end with the engaging end of the pawl (2e). The tension spring (55) ensures that if the connecting wire (57) fails / snaps and does not engage with the engaging end of the pawl (2e), the tension spring (55) keeps the engaging end of the pawl (2e) spaced apart from the ratchet’s (2i) teeth. Thus, unnecessary and surprise locking of knee is avoided by providing a fail-safe mode.

In a walking gait cycle, in stance phase, force is applicable via the heel of a person to the base plate (51) - which keeps the normally compressed resilient element (53) compressed - the connecting wire (57), in its normal operative condition, and the normally stretched resilient element (55), in its normal resting condition, does not space apart the pawl (2e) from the ratchet (2i) and keeps it engaged; thereby, locking the knee joint and lending support to a user of the orthosis to stand. In a walking gait cycle, in swing phase, force, from the heel, is lifted and, hence, is not applicable to the base plate (51) - which decompresses the normally compressed resilient element (53) - the connecting wire (57), acts due to this to space apart the pawl (2e) from the ratchet (2i) and keeps it disengaged - the normally stretched resilient (55) element is compressed from its normal tensioned state; thereby, unlocking the knee joint and allowing a user of the orthosis to angularly displace the shank portion about the knee allowing the user to walk / run / cycle.

Thus, for every cycle, there is a locking step (for stance phase) and an unlocking step (for swing phase).

Similarly, for sitting and squatting, once force from the heel on to the base plate is released, the joint unlocks. The ratchet comprises teeth covering more than half of the circumferential edge; thereby allowing a full uninhibited squatting position for a wearer of the orthosis of this invention.

Reference numeral 59 represents connecting rod (from thigh part to ratchet and from base plate to shank part).

Figure 6a illustrates a side view of the orthosis of this invention, in one of its alternative embodiments.

Figure 6b illustrates an enlarged version of the actuator assembly of the orthosis of Figure 6a.

In this alternative embodiment, a hinge (52) is provided with its first end driving support the foot assembly and with its second end providing an anchor for an auxiliary connecting wire (54) which runs from this hinge to the ratchet (2i). The TECHNICAL ADVANCEMENT of this invention lies in providing an orthosis which improves walking gait. This invention uses a drop lock to arrest the movement of the assembly. This device uses body weight of the wearer to lock and unlock the device. Essentially, the orthosis, of this invention, locks in stance phase and unlocks in swing phase whenever activated by weight. The core mechanism consists of a pawl and ratchet mechanism that locks on heel strike and unlocks when heel is not in contact with ground.

In the stance phase when the heel strikes the ground, the mechanism is activated and locks itself - with the cumulative effect of pressure plate, spring, and connective wire. The mechanism unlocks in the swing phase thus allowing the user to walk in a natural human gait for their daily activities.

While this detailed description has disclosed certain specific embodiments for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.