SOLE OR INSOLE FOR CORRECTING POSTURE WITH AN INVERTED DROP

Scope of the invention

The present invention refers to a sole or an insole of any footwear for correcting posture providing an inverted drop, by comprising higher thickness in the front (metatarsal zone) of the sole or insole and lower thickness in the back end (calcaneus zone) of the sole or insole. The present invention may also provide a higher thickness in the medial part in order to control dynamic pronation of the ankle and the consequent dynamic knee valgus that overloads the medial compartment of the knee.

Framework of the invention

Musculoskeletal pain is one of the main morbidity causes in contemporary societies, being associated with high amounts of spending by the healthcare systems. Low back pain and knee pain are some of the most frequent causes of musculoskeletal pain.

Posture is one of the main causes of biomechanical imbalances that originates musculoskeletal pain: low back pain is mostly caused by imbalances in the sagittal plane whereas knee pain is mostly caused by imbalances in the coronal plane. These imbalances are a consequence of the contemporary sedentary lifestyle that predispose to weakness of relevant muscle groups.

Knee hyperextension that is caused by weak knee extensors provide an anteriorization of the centre of mass that is compensated by an exaggerated lumbar hyperlordosis, which in turn overloads the posterior part of the disc and the zygapophyseal joints. These combined effects result in lumbar back pain to the individual.

On the other hand, hip adduction that is caused by weak hip abductors provide a dynamic knee valgus that overloads the medial aspect of the knee and the lateral aspect of the hip, causing knee and hip pain.

The present invention addresses these effects and proposes a solution to prevent back pain and knee pain from afflicting the user of the invention.

Background of the invention

A few patent documents were found that propose solutions similar to the solution proposed in the present invention but address different problems, such as "extend the leg straight" and "improve the natural healing power" (JP2005160560A), "straightening the knees" (JP2020058747A), "reduce the load on the knee during walking" (JP2005279293A) or "correct standing" (W00019851A1).

Document JP2005160560A refers to an inverted drop sole with two variants:

1. with constant inclination from heel to toe;

2. with 3 zones each with its own degree of inclination;

The construction of this sole is made in both variants with a thicker lateral side of the sole with the goal of hyperextending and forcing a knee valgus (the opposite of the purpose of the present invention: a flat sole or a thicker medial side of the sole in order to fulfil the goal of providing a knee flexion). Document JP2020058747A refers to an inverted drop sole with a constant inclination from toe to heel (different from the 3 zone construction) with the goal of "straightening the knees" (the opposite of the goal of the present invention: to provide a knee flexion).

Document JP2005279293A refers to a quadrangular foot sole support (not a sole or insole) that functions by exercising the legs of older people, with the goal of being inclined forward (the opposite of the goal of the present invention: to provide a sole or insole that aims a posteriorization of the centre of mass).

Document W00019851A1 refers to an inverted drop sole for exercise with a constant inclination from toe to heel that is higher in the lateral aspect of the foot, with the goal of forcing a knee valgus (the opposite of the goal of the present invention: to have a neutral or higher medial aspect of the foot in order to control a knee valgus).

Advantages of the invention

The present invention addresses several issues, and proposes technical solutions for:

1. Problem: lumbar spine overload due to hyperlordosis: the weakness of the quadriceps muscle and rectus abdominis muscles leads to knee hyperextension and an anteriorization of the centre of mass that is compensated by the lumbar hyperlordosis,

Solution: by tensioning the gastrocnemius muscle (a bi- articular muscle that encompasses the knee and ankle) with an inverted drop insole/sole the knee flexion is forced, with the consequent posteriorization of the centre of mass. Consequently the lumbar hyperlordosis is decreased (the lumbar spine does not have to compensate the anteriorization of the centre of mass anymore);

2. Problem: dynamic foot pronation: dynamic foot pronation during the stance phase of the gait cycle leads to a dynamic knee valgus that overloads the medial aspect of the knee,

Solution: the dynamic foot pronation may be compensated with a higher medial thickness of the sole;

3. Problem: chronic venous insufficiency: leading to tiredness of the legs,

Solution: stretching the calf muscles can compress its rich venous system and increase the blood return;

4. Problem: calf soreness after exercise in amateur or professional athletes,

Solution: the stretching of this group of muscles during the daily activities decreases soreness and improves recovery.

Unlike the documents disclosed in the prior art, the proposed invention promotes gastrocnemius muscle tensioning through ankle dorsiflexion by the use of a specific inverted drop in the sole or insole.

The gastrocnemius muscle is bi-articular, encompassing the ankle and knee joints. Consequently an inverted drop promotes knee flexion and a posteriorization of the centre of mass, provided by the tensioning of the gastrocnemius muscle. This posteriorization diminishes the lower lumbar lordosis and prevents lumbar overloading.

A higher medial aspect of the foot controls pronation of the ankle and the consequent dynamic knee valgus that overloads the medial structures of the knee. A flattened metatarsal zone prevents the foot from slipping backwards, improves foot contact with the ground during the push-off phase of the gait cycle and prevents a plantar fascia overload.

The gastrocnemius muscle has a rich venous plexus. The tensioning of this muscle promotes blood return that is relevant in venous insufficiency.

The calf muscles are a frequent aetiology of pain and soreness in recreational and competitive athletes. The stretching of this group of muscles promotes a resolution of this symptoms.

Brief description of the drawings

These characteristics, among others, can easily be understood by referring to the figures attached, which should be considered as mere examples and in no way restrictive of the scope of the invention. The figures are not to scale, and some measurements may be exaggerated for illustrative purposes. Absolute and relative dimensions do not correspond to real proportions for the use of the invention.

Figure la shows the imbalance in the sagittal plane that affects people with lower lumbar back pain: weaker Quadriceps and Rectus abdominis muscles leads to knee hyperextension with a consequent anteriorization of the centre of mass and an increase in the lumbar lordosis in order to posteriorize (compensate) the centre of mass. This increase in lumbar lordosis overloads the zygapophyseal joints and the posterior aspect of the discs. Figure lb represents the correction provided by the sole or insole of the invention: tensioning of the gastrocnemius muscle leads to a flexion of the knee and a posteriorization of the centre of mass with a correction of the lumbar lordosis (the lower back does not need to compensate the anteriorization of the centre of mass provided by knee hyperextension anymore).

Figure 2a represents the imbalance in the coronal plane that affects people with medial knee and lateral hip pain: weaker hip abductors lead to a dynamic knee valgus that overloads the medial aspect of the knee and the lateral aspect of the hip.

Figure 2b represents the correction provided by the sole or insole of the invention: pronation control of the ankle and a correction of the dynamic knee valgus.

Figure 3 represents a lateral view of the sole or insole of the invention highlighting the three zones of highlighting.

Figure 4 represents a posterior view of the sole or insole of the invention highlighting the medial thicker zone that prevents the foot from rolling inwards (foot pronation) additionally to the inverted drop sole or insole.

Detailed description of the invention

By "calcaneus zone" is meant the zone of the sole that is in contact with the heel.

By "metatarsal zone" is meant the zone of the sole or insole that is in contact with the toes. By "lateral zone" is meant the zone of the sole or insole that is in contact with the lateral border of the foot.

By "medial zone" is meant the zone of the sole or insole that contacts with the inner part of the foot.

Referencing to the figures, the invention refers to a sole on insole for correcting posture.

In an embodiment of the invention, the invention refers to a sole or insole for any footwear for correcting posture providing an inverted drop, with a thickness of the sole or insole in the metatarsal zone higher than the thickness in the calcaneus zone.

The sole or insole comprises 3 distinct zones:

- Calcaneus zone (1), a flat lower zone corresponding to from 20 to 30% of the sole or insole length;

- Transition zone (2), corresponding to a zone with a constant inclination that connects the surfaces of the calcaneus zone (1) and metatarsal zone (3);

- Metatarsal zone (3), an upper flat zone corresponding to from 30 to 40% of the sole or insole length;

- The difference of height from the calcaneus zone to the metatarsal zone is from 0,005 m to 0,03 m.

Because of this difference, the inclination of the transition zone (2) depends on the model and its purpose. For instance, the inclination of the transition zone (2) will be greater for an athlete than for an elderly person.

In a second embodiment, the invention provides medial reinforcement in order to control dynamic pronation of the ankle and the consequent dynamic knee valgus that overloads the medial compartment of the knee. This reinforcement is achieved by an inclination of the sole or insole from the lateral zone (5) to the medial zone (4), i.e., the height of the sole or insole in the lateral zone (5) is lower than the height of the sole or insole in the medial zone (4), with a constant inclination which as an angulation higher than 0° and up to 10°.