Key Insights On Orthotic Fabrication And Replacement
These expert panelists expound on replacing orthoses, determining which type of orthoses to fabricate and what types of shoes patients should wear with orthoses.
How can you tell when it is time to replace orthotic devices and do you rely on objective or subjective measures?
David Levine, DPM, CPed, notes the question of replacement frequently arises even when a patient presents for a non-orthotic related visit. If the patient is not experiencing any new symptoms or having any problems with the existing devices, he sees no need to replace them. He and the other panelists note that if the symptoms are increasing in type, frequency or severity, that might be an indication that it is time to fabricate new devices.
However, when a more detailed examination is necessary, Dr. Levine advises considering certain factors, one of which is how well the devices conform to each foot. For functional types of devices, with the foot in subtalar neutral, Dr. Levine says the orthotic should fit the contour of the foot intimately with no gapping between the orthotic device and the foot. However, he does note this is not objective criteria.
Dr. Levine says another factor for replacement is how well the orthotic conforms to the positive cast as this helps determine whether a change in the shape of the material has occurred. He notes that with softer accommodative material, wear is more visible. In many cases, Dr. Levine says it may be more cost-effective for patients to refurbish existing devices. He notes that DPMs tell patients that orthotic devices typically last from three to five years but during that time, material can wear and feet can change.
One should replace orthotic devices if there has been a change in foot morphology, material deformation or an inability of the current devices to maintain optimum alignment or function, according to Joseph D’Amico, DPM. He says improvements in arch morphology are common with the continued use of prescription foot orthoses. Dr. D’Amico adds that one can confirm this by placing the device against the foot in a non-weightbearing subtalar joint neutral position and noting whether the device contours to the foot as well as it did when one first dispensed the device. If there is a gap on the medial border, Dr. D’Amico says upon weightbearing, the foot will have to collapse down to the orthotic before it can begin to function. This may occur anywhere from six months to two years after initial dispensing, according to Dr. D’Amico. He says one should also examine patients while they are weightbearing in the neutral position in the devices.
When it comes to replacing orthotics, Lee Firestone, DPM, generally recommends replacing orthotics if they are greater than seven to 10 years old. However, he notes this timeframe changes if the integrity of the shell is compromised or if there has been significant structural change to the patient’s foot from trauma, surgery and even pregnancy. Dr. Firestone will not hesitate to replace the orthotic if the patient complains that the orthotics are no longer supportive. In addition, he will recondition an old orthotic for up to 10 years as long as the patient is happy with the orthotics and he or she remains asymptomatic.
“The bottom line is that there is a range of time that orthotic devices will last,” says Dr. Levine. “It is not as if they go bad all of a sudden so it may be worthwhile to modify, refurbish and work with existing devices prior to remaking unless they are beyond repair.”
In general, Dr. D’Amico says one should biomechanically reassess the individual every two years to see if the original device prescription agrees with the current examination findings. If there is still doubt as to whether the orthoses are functioning satisfactorily, he notes a computer assisted gait analysis may document the effectiveness of the devices.
Why do some patients prefer OTC devices to custom orthotics?
Dr. Firestone points out that patients often prefer OTC orthotics as a first-line treatment because they are more cost-effective than custom-molded devices. In addition, he says many patients present with acute situations, such as posterior tibial tendinitis and plantar fasciitis, that require immediate support. Lastly, many of his patients are runners who are currently training for a race and are in need of an orthotic on the spot.
“Since no two feet are identical in terms of structural imperfections and lower extremity influences, not only from patient-to-patient but from right to left, an OTC device can never provide individualized alignment and function for anyone,” notes Dr. D’Amico.
Since the majority of podiatric patients present with a chief complaint that has been precipitated, perpetuated or aggravated by pedal pathomechanics, Dr. D’Amico says it is not only inappropriate but also inadequate to merely treat symptoms without addressing the underlying pathology. He has found there is nothing more tolerable or preferred by the patient than a properly prescribed custom foot orthotic that addresses the underlying cause of the presenting concern.
In regard to orthotic efficacy, a factor that DPMs often overlook is the type of shoe in which the patient is using the device, notes Dr. Levine. As he explains, if one is placing a rigid device into a motion control shoe, there may be too much control and limitation of motion, making the feet, ankle and legs uncomfortable. Take the same device and place it into a more neutral shoe, and it will feel totally different, notes Dr. Levine.
Consider standing on a rigid orthotic as standing on top of a pillow, says Dr. Levine. He notes that no matter how much control the orthotic device has, there will still be instability. Do the same thing with the orthotic device on top of a book and he says the device will feel much more supportive.
“Just like glasses, there are over-the-counter reading glasses that work well for many but if there is asymmetry or they just are not quite right, then prescription glasses are necessary. The same is true with feet and the need for prescription orthotic devices,” says Dr. Levine.
How do you determine the type of orthotic device to make for your patients?
One should start with a thorough biomechanical examination when determining what orthosis to make, suggests Dr. Levine, noting that determining the mechanical characteristics of the lower extremities will start the process. For instance, he says in a foot with ligamentous laxity, a more rigid device is necessary in comparison to a foot post-triple arthrodesis. He notes the material selection depends upon the flexibility of the foot and the need for biomechanical control.
After selecting material, Dr. Levine turns his attention to casting technique. He says neutral suspension plaster, digital and foam box impressions will provide different types of devices, and different pathomechanical conditions require different approaches. Dr. Levine cautions that there is more than one type of successful device for each patient and successful devices require attention to detail, including the amount of posting and control of the foot desired. As he notes, heel and forefoot posting rely upon findings from the biomechanical exam and the goal of the treatment that one is trying to provide. Other considerations are topcover materials and orthotic width.
Dr. Firestone will generally stick with carbon fiber orthotics when he is looking for a lightweight, durable orthotic, which is important in runners who are looking to keep their running shoes as light as possible. He will also use carbon fiber for dress orthotics since that material is generally lower profile. Dr. Firestone uses polypropylene orthotics for severe overpronators, patients who need better accommodation in the shell and those he feels may need a future adjustment to the shell. He prefers full-length orthotics for athletic shoes and three-quarter length orthotics for dress shoes. Dr. Firestone will fabricate a tri-laminate orthotic with a combination of polyethylene, PPT, ethylene vinyl acetate (EVA) and Plastazote when he is looking for better accommodation.
Dr. D’Amico suggests examining the treatment objectives, which can include restriction of motion and enhancement of motion, in order to better select the type and prescription needs for the individual orthotic. The more information one gathers and the more thorough the examination, it is more likely that one will select the ideal foot orthosis and achieve the optimum foot function.
Dr. Levine adds that often there is a challenge with lab consistency in regard to the fabrication of orthotic devices. The amount of fill a lab uses on the positive cast will determine how closely the device fits up against the foot, according to Dr. Levine. As he notes, there are some devices that fit like a glove and others that have very little contour.
How do you address shoe selection when recommending orthotic devices?
As the shoe is an extension of and container for the orthotic device, Dr. D’Amico emphasizes it can either assist or detract from the orthotic’s function. Since shoes that have become misshapen as a result of compensatory pathomechanics prior to orthotic dispensing will negatively impact orthotic effectiveness and function, he advises starting with a relatively new shoe when dispensing orthotic devices. Dr. D’Amico says this allows one to house the device on a flat surface with medial and lateral “walls” to keep it in place and securely positioned. Along these lines and for most patients, he would recommend straight last shoes with a rigid counter, a longitudinal stability and a shoe capable of sagittal plane flexibility at the MPJs (or forefoot). The type of device would indicate whether there would be the need for a removable insole.
The key to an effective outcome, says Dr. Levine, is to prepare the patient for what to expect when receiving the orthotic devices so he or she will understand how they will fit and function the best.
“Dispensing a pair of orthotic devices for athletic shoes when the patient only wears dress shoes will be a failure. The orthotic device will only be as good as the shoe in which it is placed,” explains Dr. Levine.
Dr. Firestone recommends that patients bring their orthotics to the shoe store when purchasing new shoes. He also suggests buying shoes with removable insoles when possible to better accommodate the orthotics. Furthermore, Dr. Firestone says patients should purchase dress shoes with heel heights of no more than 1.5 inches and purchase new shoes later in the day after feet have had a chance to swell a little.
Dr. D’Amico is a Professor and Past Chairman in the Division of Orthopedics at the New York College of Podiatric Medicine. He is a Diplomate of the American Board of Podiatric Medicine, and a Fellow of the American Academy of Foot and Ankle Pediatrics. Dr. D’Amico is in private practice in New York City.
Dr. Firestone is board certified in Foot Surgery by the American Board of Podiatric Surgery. He is a Fellow of the American College of Foot and Ankle Surgeons, and the American Academy of Podiatric Sports Medicine. Dr. Firestone is in private practice in Washington, DC.
Dr. Levine is in private practice and is also the director and owner of Physician’s Footwear, an accredited pedorthic facility, in Frederick, Md.