In this month’s discussion, our expert panelists discuss the importance of an arthrometric exam, whether one should lean more toward accommodation or control with orthotic prescriptions, and share a few key pearls they have learned over the years in optimizing the effectiveness of prescription orthoses.
Q: Do you feel that the arthrometric examination plays a relevant role in your orthosis prescribing?
A: For Kevin Kirby, DPM, the arthrometric examination along with the physical exam and gait exam enable podiatrists to best ascertain the biomechanical etiology of the patient’s symptoms or gait pathology. Whenever Dr. Kirby performs an arthrometric examination, he records the following information for each patient: hip range of motion (ROM), frontal and sagittal plane knee position, malleolar torsion, ankle joint dorsiflexion, hallux dorsiflexion, plantar fascial bowstringing, subtalar joint range of motion, forefoot to rearfoot relationship, first ray range of motion and subtalar joint axis spatial location.
“Even though many times I find there are only a few abnormalities in the patient’s arthrometric examination, if I had not performed this examination, I would have much less objective information available for prescribing the optimal foot orthosis for my patient,” maintains Dr. Kirby.
Scott Spencer, DPM, says combining a gait exam with an arthrometric exam provides an appropriate frame of reference for prescribing an orthotic device that can achieve a change in function for the patient.
Justin Wernick, DPM, concurs about the importance of an arthrometric exam, citing its importance in determining the pathomechanics of the complaint and formulating a treatment. He does not believe most DPMs take reliable quantitative measurements. Dr. Wernick quantifies his assessment with a three-motion scale. Using this scale, Dr. Wernick is able to determine whether the joint ROM is flexible, average or restricted. He says this is beneficial in diagnosing the complaint and formulating an appropriate treatment.
Q: Some sentiment has been expressed of late that foot orthoses are over-prescribed. Do you think this is true?
A: From Dr. Spencer’s perspective, he does not think orthoses are over-prescribed. He says patients who get prescribed orthoses need them.
Similarly, when podiatrists who have a good education in biomechanics and orthotic therapy prescribe foot orthoses, they “have a great likelihood of improving a patient’s function and comfort with a minimum of potential side effects,” according to Dr. Kirby. When a podiatrist with such education and technical skills takes advantage of the full potential of prescription foot orthosis therapy, Dr. Kirby says foot orthoses “are probably under-prescribed since nearly all of their patients could benefit from prescription foot orthosis therapy.”
In contrast, Dr. Kirby notes that when DPMs without such education use orthoses, the devices do not have “near the potential” to encourage favorable outcomes for patients. Orthoses are over-prescribed in that instance as he notes such DPMs “will make many useless and uncomfortable orthoses for their patients.” Dr. Kirby says probably less than 25 percent of practicing DPMs have adequate training and experience in biomechanics and foot orthosis therapy to realize the full therapeutic potential of foot orthoses due to more of an emphasis on surgery in podiatric colleges, residency programs and podiatric seminars.
Dr. Spencer notes other healthcare professionals and general businesses that “prescribe” foot orthotics. “I am sure many of these people do a fine job,” he says. “However, I am sometimes leery of these other ‘prescribers’ due to a lack of knowledge on my part of the training they have and the ideas behind the actual device itself.”
Dr. Wernick thinks orthoses are under-prescribed. “There are so many over-the-counter (OTC) or prefabricated devices available today that, too often, people use them when a functional device would be a better choice,” he says. “You can buy glasses at a pharmacy but are they of any benefit to you?” As he emphasizes, orthotics are not arch supports but are specifically designed devices to control the joints and architecture of the lower extremity rather than just the foot.
Q: When prescribing foot orthotic devices in general, do you lean more toward accommodation or control?
A: Dr. Kirby says all of the prescription foot orthoses he makes for his patients are functional in that he designs them to reduce the magnitude of pathological internal loading forces within the foot and lower extremity. He emphasizes these orthoses also improve the patient’s abnormal gait function and accordingly relieve symptoms and restore more normal gait function. If one requires accommodation to reduce the magnitude of pathological external loading forces acting on isolated plantar areas, Dr. Kirby says one may easily modify the functional orthoses to improve their therapeutic benefit for the patient.
If the patient has an adequate range of motion in the joints one is attempting to control, Dr. Wernick notes you can influence the joints with a functional device. He does emphasize caution when it comes to determining the direction and amplitude of motion. If a patient’s deformity cannot tolerate functional control, one should use an accommodative device, according to Dr. Wernick.
When prescribing orthotic devices, Dr. Spencer tends to emphasize motion and function control rather than accommodation. As far as control goes, he does lean toward decreased control, particularly in those who have never worn orthoses. With the vast majority of his prescribed orthoses, Dr. Spencer still uses a shell of variable rigidity. He does not use an accommodative device unless his goal is even distribution of pressure across the plantar aspect of the foot as would be the case for diabetic patients with peripheral neuropathy and a gait that is primarily apropulsive.
Q: Are there any “tricks” you have found that enhance the effectiveness of your prescription orthoses?
A: For 16 years, Dr. Kirby has used a medial heel skive to selectively increase the subtalar joint supination moment from foot orthoses for more effective treatment of those with symptoms and pathologies caused by excessive subtalar joint pronation moments. He also commonly uses a lateral heel skive to treat symptoms such as peroneal tendonitis and chronic lateral ankle instability, as well as lateral midfoot and forefoot symptoms caused by excessive subtalar joint supination moments. Dr. Kirby notes that adding 3 to 6 mm heel lifts to orthoses frequently abates plantar arch irritation from orthoses and permits resupination of the foot to occur earlier during gait.
Dr. Kirby also says having the anterior edge of the orthosis 5 to 6 mm thick, as opposed to skived thin, frequently leads to great improvements with metatarsalgia and other metatarsal head symptoms. Not only do plantar fascial accommodations make orthoses more comfortable but Dr. Kirby emphasizes the accommodations’ importance in improving the orthoses’ therapeutic effectiveness for various pathologies.
Dr. Wernick cites the “trick” of viewing the position of the hallux in relation to the first metatarsal shaft. He says the normal resting position should be 15 degrees of dorsiflexion of the hallux. If the angle is diminished or the toe is directly aligned with the metatarsal, this indicates that the first metatarsal is dorsally dislocated, according to Dr. Wernick.
When casting the orthotic devices, Dr. Wernick advises one to dorsiflex the hallux to approximately 15 degrees. He says one can do this by dorsiflexing the toe while plantarflexing the metatarsal.
Dr. Spencer is interested in some of the different ways one can assess patient function and prescribe a foot orthotic device. He is “especially intrigued” by using the F-Scan to assess and prescribe foot orthotics by looking at the distribution of pressure and progression of the center of mass. By modifying an orthotic shell to create a more symmetrical presentation of those two factors, one can alleviate pathology. As Dr. Spencer says, the F-Scan method eliminates “much of what we do now in orthotic assessment but it is more time consuming.”
Dr. Kirby is an Adjunct Associate Professor in the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt College. He is also the Director of Clinical Biomechanics for Precision Intricast Orthosis Laboratory. Dr. Kirby has a private practice in Sacramento, Ca.
Dr. Spencer is an Associate Professor of Orthopedics/Biomechanics at the Ohio College of Podiatric Medicine. He is also a Diplomate of the American Board of Orthopedics and Primary Podiatric Medicine.
Dr. Wernick is Professor and Chairman of the Department of Orthopedic Sciences at the New York College Of Podiatric Medicine (NYCPM). He is also a Diplomate of the American Board of Podiatric Orthopedics and is the Medical Director of Eneslow Comfort Shoes and Langer, Inc.