These “off the shelf” orthoses have been specifically designed for patients with a medially deviated subtalar joint (STJ) axis. With a 4mm built-in heel skive, they offer excellent biomechanical support for patients whose foot type is difficult to control.

As with all of the Bio-Insoles, Bio-Skive can be specifically tailored to your patients’ needs with additional adhesive components or heat moulding.


What is a Medial Heel Skive?

A medial heel skive is a modification which is made to a positive cast by taking away small amounts of the medial portion of the plantar heel.  This creates an intrinsic varus wedge effect within the heel cup of the foot orthotic. The result is increased pronation control within the foot orthotic.

Until recently, this technique could only be achieved with custom made orthoses. Bio-Skive are the first “off the shelf” devices with this modification incorporated.


What is a Medially Deviated Axis?

Most patients have what is called a “normal STJ axis”. However, this axis can also occur more medially or more laterally. Effectively if you put a force (such as a strip of posting) under the medial side of an orthotic you will cause the foot to supinate at the axis line. If you put forefoot posting under a medially deviated axis, you will cause the foot to pronate rather than supinate because it’s the wrong side of the axis. Basically the only area you can moderate is the small section of the orthotic which is medial to the axis line; this is why medial heel skives can be very effective.

     Medial               Normal                Lateral

For further information about medially deviated axes, watch our 40-minute webinar which explains what it looks like, how to test for it and how to manage it.

Watch our Tissue Stress Theory Webinar


Key features

  • 4mm built in heel skive = Combats medially deviated STJ axes
  • Removable 1st met and 1st ray plugs = Helps functional hallux limitus or plantar flexed 1st
  • Includes additional adhesive components = Increase control
  • Heat mouldable low or medium density EVA = Can be shaped to the contour of the foot
  • Soft spot under the heel = Plantar heel cushioning
  • Deep heel cup = Increased calcaneal support
  • Contoured arch = Supports the sustentaculum tali


Ideal for

  • Patients with a medially deviated STJ axis
  • Patients with Adult Acquired Flatfoot
  • Tibialis Posterior Dysfunction
  • The hypermobile foot
  • Paediatric flexible flat foot
  • Patients with a High Supination Resistance test
  • Any patient requiring additional amounts of pronation control


Treatment Tips

  1. Although the Bio-Skives are indicated for patients with a medially deviated axis, they can in fact be used for any lower limb pathology which is aggravated by excessive STJ pronation. The inbuilt skive, coupled with additional posting, can be very effective where conventional orthoses do not offer enough control.
  2. The Bio-Skive has a standard 4mm skive incorporated. This is usually enough when used in conjunction with additional external posting. However, for increased pronation control, additional layers of mole-skin or thin semi-compressed felt can be added to the skived area on the inside of the Bio-Skive’s heel cup. This should be applied in line with the clinician’s judgement and the patient’s tolerance.
  3. Avoid using the Bio-Skive for patients who suffer from conditions such as plantar heel spurs, plantar heel bursitis and medial calcaneal nerve entrapment. The flattened area on the inside of the heel cup may aggravate symptoms.
  4. Avoid using Bio-Skive for patients with a laterally deviated STJ axes or lateral ankle instability. Due to the longer lever arm created by the device, these patients may be at a higher risk of lateral ankle sprain.