Biomechanics clinicians rightly focus on the relationship between the patient’s anatomy and how it may be positively impacted by use of a corrective device. However, the orthotic device is not the only factor in determining a successful clinical outcome, as it must be placed within some sort of shoe gear in order to function properly. In other words, you may be able to create an orthotic device that functions precisely as you desire, created following a precise physical examination, and an accurate impression and prescription, yet the results are less than optimum due to not having the device utilized properly in the correct shoe gear. So, let's talk a little about shoes, how they are made, and how we can make correct choices with our orthotic devices.
Shoes are generally constructed upon a physical form called a “last”. According to Wikipedia, “A last is a mechanical form shaped like a human foot”. Traditionally they were handmade in wood, with a library of sizes and shapes. Today, plastic is used most frequently, manufactured with computer aided design systems. A quick internet search for “shoe lasts for sale” will provide a myriad of choices for all kinds of shoes. Lasting can also be a term used for the actual construction process of the shoe, and basically can be divided into the following categories; slip lasting, combination lasting and board lasting.
Slip last shoes generally are the most flexible type shoe, the upper of the shoe wraps around the last completely and is sewn to itself on the bottom surface, then the sole of the shoe is attached. A modification of the slip last is the Strobel last, which has a reinforced bottom surface. Many contemporary shoes, including athletic shoes, are made with this technique.
Combination lasting involves a Strobel type last with a reinforced toe cap area. This allows more solid construction in the forefoot, such as hiking boots.
Board lasted shoes are the most stable, and durable constructed shoes, they are made with the upper pulled over a stiff material on the bottom of the last and attached either by glue or stitching. This technique is used for many leather dress shoes, work boots and supportive running shoes.
There are many variations of these categories and resources are available to familiarize yourself with the art of shoemaking.
Another classification of shoe lasting to touch upon is based on the shape of the shoe last. A shoe or boot may be either a straight last, curved last or semi-curved last. Examples of these shapes are based on the alignment between the front and back halves of the shoe. A good shortcut is to describe the straight last shoe as shaped like an upside down bowling pin, and the curved last shoe shaped as a kidney and the semi curved last shoe as in between. Generally speaking, the straighter the last, the more supportive the shoe. Knowing the shape of the shoe is critical when using full length orthotics, especially when curved lasted shoes are being used by the patient so the lab may adjust the extension accordingly.
Shoe history and examination should be performed whenever considering a biomechanics based treatment plan is being implemented. Subjectivity plays a large role when determining what course to take in terms of orthotic control. What does the patient find most comfortable? How is the shoe wearing out? Is the shoe the proper length and width? Are they willing to change their preferences based upon your advice? Examine their shoes, can you ring it out like twisting a towel or fold it in the midfoot? Is there flexibility or is there a rocker action in the forefoot? How much is the shoe choice contributing to the chief complaint?
Today’s trend in shoes is lightweight athletic looking shoes either slip lasted or Strobel lasted on a foam sole material. They are lightweight and initially comfortable to wear, also relatively inexpensive to manufacture. This also weakens the foundation upon which the orthotic must seat. When making an orthotic for this type of shoe a firm frame reinforcement should be utilized to allow the highest amount of contact area between the orthotic and the shoe.
The shoe is often the overlooked variable in your biomechanics based equation. Please consult with the KevinRoot Medical website for further information.
