When prescribing orthoses we need to take into account our orthotic casting method. This casting method can change a variety of parameters. This will alter the finished product and effect its ability to do its job and be comfortable. In today’s post we will examine the difference between weight-bearing and non-weight-bearing casting.
This is done with the patients foot suspended in the air and the subtalar joint placed into neutral. A cast is then taken using plaster or a 3D scanner. This technique allows the podiatrist more control of the positioning of the foot. Thereby, allowing them to capture the foot in the ideal position. However, this does come with some faults. Subtalar joint neutral is not an exact science and thus differences between podiatrists are common. Furthermore, arch height is increased with non-weight-bearing compared to weight-bearing. This must be considered when prescribing for arch fill. Also, foot length and width are reduced in non-weight-bearing. The orthotic will need to be enlarged to account for the expanded width and length.
Weight-bearing orthotic Casting
Semi weight-bearing is with the patient seated with foot on the scanner/foambox. Full weight-bearing is with the patient standing. This orthotic casting technique is thought to be more representative of the foot during gait. Therefore, the arch height is reduced compared to non-weight bearing. This means less arch height adjustment is needed for the orthotic to be comfortable. Furthermore, as weight is applied during casting, little to no width or length expansion is needed. A limitation of this method however is the tendency for the patients foot to move during casting. This can lead to a flattened arch contour or a navicular bulge, reducing its ability to do its job.
So Who Wins?
Most patients find orthotics made from weight-bearing casts are more comfortable. Comfortable orthotics are worn orthotics. This is important when trying to treat a patient. However, non-weight-bearing casts can be done right too. So who wins? Well that’s up to you. As long as you know the pros and cons for both techniques and adjust the prescription appropriately the patient should be a happy customer.