Pathology Specific and Specialty Orthoses
Topcovers, Extensions and Additions
Cast Fill and Arch Height
What are the differences between vacuum-formed and direct-milled (CD) polypropylene orthoses?
There are three main differences:
- Production Method
- a. A vacuum-formed device is a ProLab exclusive technique which results in the polypropylene being precisely formed over the positive. The mold can be either a wood positive or a plaster positive mold. This vacuum-forming method ensures an exacting fit, long life, and allows the widest variety of orthotic modifications.
- b. The direct-milled method produces a custom orthotic device without creating a physical positive mold. We individually scan, correct, and store the image of each cast in our CAD/CAM system. The orthoses are then milled directly from polypropylene based on the individually-corrected “virtual mold”. This production method allows us to offer fully corrected custom orthoses at a value price.
- Rigidity or thickness - For the same thickness of polypropylene, a direct-milled orthosis will be more rigid than a vacuum-formed orthosis allowing you to prescribe a thinner device when using a direct-milled orthosis. Practitioners can indicate the desired rigidity and the patient’s weight on the prescription form and we will select the appropriate thickness to provide the correct rigidity.
- Available options - There are a few modifications that can only be accomplished with the vacuum-formed method: sweet spot, plantar facial groove, EVA rearfoot post, Blake inversion, extra high medial flange.
When do you recommend using a graphite shell?
The advantage of graphite orthoses is that they are very thin for their relative rigidity. The disadvantage is that they have a greater tendency to fracture compared to polypropylene. We recommend using graphite for shallower or narrower shoes, and for activities that do not involve repetitive impact. The best use for graphite is in women’s dress shoes.
What makes some orthoses thicker than others?
Several prescription items can increase orthotic thickness: shell choice, patient weight, rearfoot posts, and additions such as metatarsal bars and forefoot extension. Graphite is the thinnest shell material; however it is not always the most appropriate choice. Polypropylene thickness varies based on flexibility and patient weight (see chart on prescription form ). Additional layers of cushioning added to the orthosis cover also increases the overall thickness of the device.
Do you accept foam box impressions for functional orthoses?
Several studies have demonstrated that foam box impressions capture excessive forefoot varus relative to non-weightbearing impressions. This leads to excessive varus in the orthosis, and excessive varus in the orthosis can exacerbate certain pathologies, such as functional hallux limitus. More information is provided on our casting page.
When should I recast my patient for functional foot orthoses?
ProLab stores digital images of your patient’s feet for at least seven years. Although there are no hard and fast rules, we recommend recasting after 5 – 7 years or anytime that there has been a change in the foot. Always recast after surgery or significant trauma.
Why do I need to recast my patient for their Stabilizer Gauntlet AFO?
ProLab strives to make the best possible product for your patient. Every AFO cast is evaluated by one of our Medical Consultants. If the foot was not captured in the proper position, the resulting AFO will likely have fitting, comfort, compliance, and effectiveness issues. In order to avoid this, Medical Consultants will contact you if they find anything questionable with the cast and may ask that it be redone. The most common casting error occurs when the ankle joint is not at a 90°. You can watch our video on proper casting technique.
Why did the orthosis come with a metatarsal bar, when I didn’t order it?
Part A of our prescription form provides predetermined prescriptions designed to facilitate prescription writing with our one-check options. When you check a box in Part A, you will receive a device as described on the back of the Rx form. For example, if you check "Metatarsalgia", you are prescribing an orthosis that is optimized to treat metatarsalgia with a minimum fill, no skive on the distal edge, a topcover, and a metatarsal bar. For a complete description of each of the Pathology Specific and Specialty Orthoses, look on the back of the ProLab prescription form.
Why is the front of the orthosis thicker on the Metatarsalgia device?
We leave the front edge of the orthosis thick in order to transfer force off of the metatarsal heads and onto the metatarsal necks. This acts like an intrinsic metatarsal bar. If it causes irritation it can easily be beveled.
What is the best orthosis for a dress shoe?
A graphite orthosis with a shallow heel cup, narrow width, and vinyl topcover will fit many dress shoes. However, depending on your patient’s shoe collection, it may not be reasonable to expect one type of orthosis to fit all dress shoes, making it essential to discuss these issues with your patients before ordering. If the device is going to be used in a variety of shoes with a heel height of 2” or more, the cobra device will probably work best. We recommend sending a sample dress shoe in with the order.
What makes a “dress” type of orthosis different than a regular orthosis?
The simplest answer is size. Dress devices are made narrower and generally with a shallow heel cup to fit into a greater variety of shoes. It is important to keep in mind that dress orthoses provide less control and can not be expected to provide the same control as a full-sized regular orthosis.
When do you recommend ordering a topcover?
Topcovers are not always necessary, and are often prescribed as a result of doctor and/or patient preference. Topcovers are necessary when the patient’s pathology requires a forefoot extension or if there is an accommodation, such as a sweet spot built into the orthotic shell. Both our vacuum-formed and direct-milled polypropylene orthoses are polished so they can be worn without a topcover. Graphite shells will always include a topcover due to the material composition.
When I request a forefoot valgus/varus extension how many degrees do I order?
Theoretically, you should match the amount of valgus or varus in the forefoot-to-rearfoot relationship. More than 5 degrees, however, can get quite thick and therefore difficult to fit in shoes. The average is usually 3 - 5 degrees.
What is the difference between minimum fill and maximum fill?
The fill denotes the amount of plaster that is added to the medial arch when making a positive cast. Since most of our corrections are done on computer now, this refers to the virtual plaster that is added in our corrections process. Minimum fill means that very little plaster is added to the medial arch, so that when an orthosis is made from this positive cast it will have a higher arch that hugs the arch of the foot. Maximum fill means that more fill is added and the orthosis will gap from the arch and the orthosis will have a lower arch.
When should I use minimum fill and when should I use standard or maximum fill?
Studies on orthotic therapy for hallux limitus, metatarsalgia, plantar fasciitis, tarsal tunnel syndrome, neuropathic ulcerations and pes cavus all indicate that orthoses that conform closely to the arch (total contact orthoses) are more effective at reducing abnormal tissue stress and symptoms than devices that gap from the arch. Therefore, we recommend minimum fill for most pathologies. Patients with equines often do not tolerate minimum fill so prescribe standard or maximum fill for those patients.
NOTE: Impeccable casting techniques are required for successful use of minimum fill since the orthoses will accurately mirror the foot position during casting. Watch our casting video or contact a Medical Consultant with any questions.
If my patient complains of arch irritation, can the orthoses be adjusted?
There are numerous factors that can cause arch irritation and the orthoses can be easily adjusted. For direct-milled polypropylene orthosis, simply grind the orthosis on the bottom of the shell to make it thinner. This increases the flexibility of the device and decreases the force it is applying to the foot. Graphite orthoses or vacuum-formed devices can be gently heated to lower the arch.
If someone is a runner, is it acceptable to order a semirigid or rigid device?
There is no evidence that runners should not use semi-rigid or rigid orthoses. In fact, studies show that orthoses work by reducing stress on tissue that is being overstressed, decreasing tension on a plantar fascia that is being overstretched. In order to resist abnormal forces a device must be rigid enough to resist deformation. Thus, in order to treat the more common problems treated with orthotic therapy, a device must be somewhat rigid, regardless of the patient’s activity.
Are there any special orthotic modifications that should be used for runners?
In general, you want to prescribe your orthoses to best treat the pathology – not the activity. There is, however, a study showing that adding extra cushion to the top of an orthosis will decrease shock throughout the lower extremity. Given that, we often recommend adding an extra 1.5mm layer of Poron under the topcover if the patient is going to use the orthoses for running.
What happens when I write “Call Doctor” in the special instructions?
These orders are held on a special shelf so that the medical consultant can call the prescribing doctor. This can delay the production of your order. If you need to talk to a consultant about an order, please call us before the casts are shipped. We have Medical Consultants available every weekday.
What are things that I can do to assure that my orthoses provide optimum clinical outcomes?
- Ensure you are educated on the latest research and recommendations regarding foot orthosis therapy. Attend seminars, subscribe to our E-Journal Club, and use our links to read the orthotic therapy articles available in our education section.
- Use evidence-based orthotic therapy by prescribing orthoses based on each patient’s specific pathology.
- Complete the Rx form.
- If you have questions on the best prescription for your patient, call one of our medical consultants.
- Take a negative cast with the subtalar joint in neutral, the midtarsal joint locked and the first ray plantarflexed (watch our casting video)