When it comes to prescribing foot orthotics, a one-size-fits-all approach does more harm than good. Notably, patients have unique characteristics and needs that can only be addressed effectively with custom orthotics. Thus, podiatrists must consider each patient's particular dysfunction to achieve a satisfactory treatment outcome. For instance, prescribing orthotics designed for posterior tibial dysfunction to a plantar fasciitis patient yields undesirable outcomes. That said, constructing custom foot orthotics requires a systematic approach to ensure the devices achieve the objective. This article highlights critical steps in custom orthotics fabrication.
History of Injury and Biomechanical Exam
The first thing a podiatrist will discuss when you walk in with a foot or leg complaint is the injury history. You will do most of the talking at this stage as a podiatrist tries to establish the problem's progression. It is crucial because injury history dictates the type of biomechanical tests a podiatrist administers. After discussing your injury history, a podiatrist will proceed with a biomechanical examination. Here, a podiatrist evaluates your feet while you stand or lay supine and notes any abnormalities in joint motion and bone alignment. Any misalignments or abnormalities can cause overuse stress, leading to tissue damage, pain, and instability.
Podiatrists cannot construct or prescribe custom orthotics without gait analysis. Therefore, a podiatrist will ask you to walk and run to analyze your frame. Overall, gait analysis refers to the study of body motion using augmented instruments that measure body movements, mechanics, and muscles activity. Gait analysis is essential to podiatrists because it helps confirm if further biomechanical testing is necessary. Notably, a gait analysis determines if you have unbalanced legs or flat feet. In addition, an in-shoe pressure measurement might be necessary for advanced analysis, helping a podiatrist construct fitting custom foot orthotics.
Plaster Casting and Fabrication
The final step in custom foot orthotics is plaster casting and construction of the device. Plaster casting captures the exact form of a foot and is determined by joint flexibility. If you have an existing foot issue, such as arthritis, that reduces your foot range of motion, a podiatrist uses a semi-weight bearing casting technique. In this case, the casting is taken with you in the seated position, with the knee joint at a right angle. Podiatrists often use a foam box for this type of foot casting. On the other hand, podiatrists use neutral position casting if you do not have joint restrictions on your foot. Unlike semi-weight bearing casting, neutral position casting is performed when lying on an examination table. Once the casting is ready, it is used to make a mould to fabricate your custom orthotics.