Foot malpositions; flat valgus foot, splayfoot, flatfoot, hollow foot

Posted by kyBoot Shoes on

Foot malpositions; flat valgus foot, splayfoot, flatfoot, hollow foot

Congenital or acquired foot deformities constitute a more or less pronounced deviation from the normal foot shape. They fundamentally impair body statics. Knee problems and other complaints often result.

In order to prevent the condition from deteriorating, it is important to treat the cause. In most cases there is an underlying foot instability, which can be significantly improved through strength, coordination and mobility training.

In the kyBoot/on the kyBounder, you can move your feet freely in all directions and thereby regain your natural mobility. You can easily strengthen your feet as part of your daily routine while actively counteracting pain and signs of wear in the joints at the same time.



  • Kinked foot, flatfoot, pes planus deformity
    Flatfoot refers to a flattening of the longitudinal arch from the heel to the ball of the forefoot. Typically the foot is abducted and the ankle protrudes on the inside (abducted foot). These two foot malpositions often occur in combination. If the condition worsens, the longitudinal arch lies fully on the floor (flatfoot).
  • Splayfoot:
    Splayfoot is the term used to denote the spreading of the metatarsal bones. Over time, the sinking of the transverse foot arch leads to foot complaints with widening of the forefoot. Load-dependent pain is the main symptom. This occurs primarily while walking and standing, and decreases at rest. Foot widening leads to complaints when wearing shoes.
  • Hollow foot:
    The term hollow foot refers to a foot deformity where the foot exhibits an overly defined longitudinal arch.



  • As a rule, the kinked flatfoot is caused by a weakness of the foot musculature which normally supports the foot arch. While this weakness is normal in infants, it should disappear within a few years. However, a lifestyle without sufficient exercise, reinforced by the immobilization of the feet in shoes, often means that the foot musculature is not given the training stimuli it needs. As a result, the muscle strength required for a stable foot arch is not developed, even in youths and adults. Foot weakness is almost always the cause of flatfoot.
  • Flatfoot can be a congenital or an acquired foot malposition.
    Congenital flatfoot is comparatively rare and occurs in combination with other malformations in about 50 per cent of cases.
    Acquired flatfoot usually results from inadequate muscle and ligament function. Possible causes include insufficient training (constant sitting and wearing of shoes), overtaxing of the feet due to excessive weight or standing for long periods, connective tissue weakness, heel bone fracture (‘post-traumatic flatfoot’) and diseases such as poliomyelitis, rickets and neurological and rheumatic disorders. The ankle bone is in the normal position on X-rays.
  • Splayfoot usually develops due to years of improper strain on the foot. Splayfoot is not caused by a lack of exercise, but usually by wearing unsuitable shoes and especially shoes with heels. Wearing high-heeled pumps increases front-foot load by a factor of five. Connective tissue weakness (especially among women, who have a genetic predisposition) is another reason for increased width of the front of the foot.
    Often, the affected individual rolls over the outside edge of the foot while walking. The right way would be to ‘push off’ over the big toe. Poor footwear or hard surfaces are usually the reasons for an ‘incorrect rollover’. Stiff shoes greatly limit the foot’s freedom of movement. The foot musculature grows increasingly weaker as a result and one begins to compensate with an unfavorable ‘rollover’ while walking. As a result, the foot keeps getting weaker, the transverse foot arch becomes insufficient and splayfoot develops.
  • A contracted foot is usually congenital, running in families.
    Other causes include paralysis and nerve damage to the foot musculature. A weakness in the foot musculature and ligaments can also be a cause. Sometimes the hollow foot is the first sign of muscle weakness or a muscle disorder.

Long-term consequences

A failure to address and treat foot malpositions and their causes usually results in pain and wear in the feet, and later in other joints as well.

Orthopaedic insoles are often prescribed. This can provide short-term foot relief, but is not a good solution over the long term in most cases since passive support is provided for the feet so that the muscles keep getting weaker. This does not improve the foot malposition over the long term. Quite to the contrary, the foot gets accustomed to the insoles and the pain often returns as a result.

Those who depend exclusively on passive insoles are not doing anything about the cause of an acquired foot malposition. Usually the foot musculature is severely weakened and foot mobility is restricted. Then, when the weakened feet are also supported by insoles, the foot moves even less freely and the foot musculature is weakened further. This causes the foot malposition to deteriorate further.

In the course of life, this leads to a risk of pain caused by excessive strain on the weak foot musculature, knee damage caused by incorrect force transmission while walking and standing, the development of a painful heel spur, intervertebral disc and back problems due to the disruption of movement patterns and inadequate dampening of impact because the arch of the foot has sagged.

Conventional therapy

  • Orthopaedic insoles
  • Physiotherapy (foot exercises)
  • Medications (painkillers)

The kybun principle of operation – being proactive

We recommend both the kyBounder and the kyBoot for users with clubfoot, splayfoot or any other acquired foot malpositions (those that result from weak foot musculature). Standing directly on the soft, elastic surface trains the core foot musculature and improves foot mobility. The core foot musculature is often severely weakened in case of foot problems. As a result, the foot is no longer stabilized properly. This can lead to pain and even more severe malpositions over time.

With the kyBoot or kyBounder, the foot can again move freely in all directions, much like walking barefoot on a soft surface. This strengthens the core, stabilizing foot musculature. Stability is improved in cases of splayfoot, clubfoot or flat foot. It has been proven that an insufficient or flat arch of the foot can be stabilized by muscle training and the complaints are alleviated as a result. This can prevent the condition of the foot from worsening and protects the joints above the foot.

The more often the foot musculature is trained, the faster the foot position will improve and the pain alleviated. In the kyBoot/on the kyBounder, you can integrate the training into your everyday life without spending extra time and thereby challenge your foot musculature continuously over the course of the day.

Initial reactions

Specific initial reactions with foot malposition:

In the beginning, users with club foot or flatfoot may find that their feet tip slightly to the inside or that club feet cannot be held upright in the kyBoot/on the kyBounder. This can lead to foot pain or, often, to knee pain. Please read the ‘Application tips’ and ‘Exercises’, which will help you to avoid these initial reactions.

Users with splayfoot may experience pain in the front of the foot in the beginning when they are still unaccustomed to the kyBoot/kyBounder. This initial reaction will disappear as soon as your foot musculature has been strengthened in this area. Please read the ‘Application tips’ and ‘Exercises’ to avoid such foot pain.

Click here for the general initial reactions experienced by kyBounder and kyBoot beginners: Initial reactions

kybun exercises

For information about the special kyBoot exercises or the basic kyBounder exercises , please click here: kybun exercises

The following adaptations to the standard implementation of interval walking are important in case of clubfoot and splayfoot :


  1. Focus on slow exercises because it is then possible to consciously control the movements (correction of pronounced twisting to the inside)
  2. Switch to fast exercises if you get tired


  1. Avoid excessive strain on the forefoot (the arch is pushed down by a forefoot load)
    - Take shorter steps
  2. Perform slow exercises slightly faster in case of discomfort in the forefoot
  3. Alternate exercises as directed

Application tips

For active stabilization training of the foot, we advise wearing the kyBoot without orthopaedic insoles. The foot musculature needs several months of regular training before it is strong enough to walk several hours in the kyBoot. Until then, you can wear normal shoes with insoles for relief. After years of using insoles, wearing the kyBoot all the time may be too much for the feet in the beginning (in the first weeks/months).
Insoles provide passive support for the feet but do not improve the foot situation over the long term in any way. We recommend against constantly wearing orthopaedic insoles. It is best to listen to your body, since it tells you what is good for it and when it needs a break.

Pay attention to putting an even load on the sole in the kyBoot and ensure that the foot stands upright on the sole. This gives you a favorable leg axis and also prevents the feet and knees from ‘rolling in’ as much.

Avoid making your steps too long; this makes it easier to maintain a good foot position in the kyBoot. This reduces rolling to the inside.

Some people feel too unstable in the kyBoot. In this case, we advise you to try various kyBoot models; some models with a higher cut provide more stability. We also recommend that these customers try the second generation sole. It is a bit wider in the midfoot area, therefore making you feel more stable while walking (ask for advice in a kybun specialized shop).

If you still feel too unsafe walking in the kyBoot, we advise using the kyBounder. The kyBounder is available in three different thicknesses. This allows you to choose the thickness that is most comfortable for you (the thicker, the more unstable, the more intensive the training).
You can also hold on to a fixed object if you need additional support when using the kyBounder.

With splayfoot, it is important to train the core foot musculature and promote foot mobility.
If you experience pain in the kyBoot in the beginning, we recommend that you insert a small cushion or a fairly stiff insole (available at a chemist’s) under the arch. This supports the transverse arch and prevents hyperextension (pain). Once the foot musculature gets stronger (through training in the kyBoot/on the kyBounder among other things), the anterior transverse arch is stabilized and you may be able to do without the padding or stiff insole again.

Share this post

← Older Post Newer Post →