Long Saddle

Healthystep’s insoles offer superb 3-dimensional comfort contouring of the foot’s ‘arch’. 

The company’s clinical experts have always viewed the foot as possessing a complex multi-tied viscoelastic asymmetrical conical vault. This is a structure that enhances abilities to shock absorb and store energy. It does this through deformation and muscle-induced shape changes to alter stiffness and compliance across the foot in an adaptable manner. 

Although we won’t be changing our insole profiles (because we know they are the best standard profiles on the market), we recognise that sometimes muscle dysfunction is such that a higher profiled support is necessary. Commonly, this is just required on a temporary basis until rehabilitation can start to improve the situation.

Experienced experts in foot orthosis prescription have long used bespoke saddle-profiled additions, but these are the first commercially produced standardised saddles. Being made of TPU means they can both support and shock absorb under the planter foot when the natural ‘arch’ biomechanics are failing. This adds an extra dimension of customisation to HealthyStep’s inbuilt comfort contouring profiles across its orthotic ranges.

Engineering laws state that structures can stiffen by increasing their curvature (by decreasing the radius of curvature) and by shortening the distance between supports, known as the span distance. By having an asymmetrical concave under-surface, the plantar foot can alter both curvatures and span distances longitudinally, transversely, and obliquely. Increase the vaulted profile of the foot and it will stiffen. Increase the length of the longitudinal arch and it becomes more flexible. Muscle contractions and connective tissue tensions in ligaments and fascia also play an important part in creating greater compliance or stiffness. However, by having a plantar vault, soft tissues can create profile changes that enhance these properties. Stiffen a structure actively is easier to achieve by increasing curvatures across the shortest spans. Thus, stiffening the foot is easiest through the transverse plane, from medial to lateral, rather than trying to do so across longer longitudinal ‘arches’.  

During a step, the foot increases its vaulted profile before forefoot loading by activating muscles that create extra elastic stiffness. Once the forefoot makes ground contact, this elasticity is used as a shock absorber as stiffness is reduced through muscle relaxation. This allows the vaulted profile of the foot to flatten rapidly to act as a shock absorber. Thus, during the early stance phase, the foot should lengthen and widen more rapidly than at any other time, but in a controlled manner.  

Once bodyweight has passed in front of the ankle it is important for the foot that it starts to stiffen. The foot now continues to flatten, lengthen, and widen, but at a much slower rate as the foot’s connective tissues tension to stiffen and muscles supporting the foot become increasingly active. This mix of passive and active stiffening activity causes shape changes that increase the curvature of the forefoot transverse plane vaulted profile. This decreases the amount of muscle power required to make sure the foot is stiff enough for the heel to lift without the midfoot buckling (known as midfoot break).

Damage or weakness to muscles or ligaments within the vault can change all this ability and sometimes dramatically so. The standard comfort-contoured profiles of Healthystep insoles reflect the far more common but less severe issues with vault biomechanical dysfunctions. 

The X-line TPD design reflects the importance of tibialis posterior in foot vault mechanics.

The Long Midfoot Saddle is an addition that passively maintains longitudinal and more importantly, transverse plane contouring under the vault even when the natural soft tissue mechanisms have significantly failed. This is extra ‘arch’ support but applied in a far more scientific manner than adding material under the medial long arch alone.