This is prescribed depending on your foot position when weight bearing. We would identify if your foot pronates (flattened arches) or supinates (higher arches). This changes the angle of your heel and predisposes you to several conditions such as Achilles pain, plantar fasciatis, bunions, calcaneal spurs, ankle sprains, knee pain, lower back pain and pelvic asymmetry
In order to prescribe the orthotics we would consider if you really needed one or if you have a structural limb length difference. In the later, you may require a heel lift We also prescribe orthotics depending on the type of sport you play and would recommend a good sports shop where you could get sound advice on different shoes.