Addressing shoe gear, medial tibial stress syndrome and other factors unique to runner patients, these experts share their experiences with orthotic features, modifications and materials for optimal outcomes.
When treating patients who have injuries that seem to be caused mostly by their running activities and not so much by their walking activities, how do you specifically design their custom foot orthoses? Are the orthotics running-specific or is your design geared to accommodate running and walking activities? Alternatively, do you make one set of orthoses which is running-specific and another that is walking-specific?
Kevin Kirby, DPM, and Simon Spooner, PhD, opt for a running-specific orthotic if the patient has only developed injuries as a result of running activities and has no symptoms when walking.
“I want to specifically design the orthosis for the very different foot and lower extremity biomechanics that occur with running,” states Dr. Kirby.
In his experience, Bruce Williams, DPM, notes that runners often only wear their orthotics when they run. In these cases, he notes he will modify the device specifically for their running type. Dr. Williams says he encourages runners to wear their orthotics for all activities so he prefers a device that is appropriate for both running and walking. He adds that he rarely chooses separate prescriptions for each type of activity.
Conversely, Dr. Kirby prefers one running-specific pair of orthotics and one walking-specific pair if cost is not an issue. He cites the opportunity to biomechanically tune each pair as a benefit but will make one pair for both activities if necessary.
There seems to be a growing belief that runners should only use custom foot orthoses in “neutral” running shoes and not use them in either “stability” or “motion control” running shoes. How do you alter running shoe recommendations for your runner patients with custom foot orthoses?
Dr. Williams feels practitioners need to ask themselves if the shoe and orthotics are built to do the same things.
“I think a lot of docs are concerned and rightfully so about overcorrection,” notes Dr. Williams.
He goes on to relate that recommending motion control shoes with an aggressive custom foot orthotic could lead to a potential overtreatment scenario.
Dr. Kirby and Dr. Spooner feel the association is less clear. Dr. Kirby cites a lack of research evidence supporting the idea that a neutral running shoe is preferred for runners with custom orthoses. Using the example of over-pronation, he relates he will design an orthotic to counteract this with features such as a medial heel skive, an inverted balancing position and a congruent medial arch. Dr. Kirby subsequently recommends a running shoe that will not allow the orthotic to excessively evert inside of it.
Dr. Kirby additionally recommends a weight-based system of choosing the appropriate running shoe for such a patient. For lighter runners less than 150 pounds, he may choose a more cushioned, neutral shoe. For runners between 150 and 200 pounds that have more pronated feet, he recommends a stability shoe with a less cushioned medial rearfoot midsole. Lastly, for runners over 200 pounds, in order to avoid overcompression of the midsole, Dr. Kirby advocates a motion-control shoe.
In certain cases, Dr. Spooner has found that a change in shoe type in isolation may resolve the injury, even without an orthotic. However, he adds that one cannot solve all running-related injuries with one type of shoe. Both Dr. Williams and Dr. Spooner advocate for patient-specific selection of a shoe and orthotic combination.
“If we view that most running-related injuries are due to forces exceeding the loading capacity of the tissue and that both footwear and orthoses are devices that have the potential to modify ground-reactive forces to the lower limb, we must consider their effects as an additive series,” maintains Dr. Spooner.
Dr. Spooner illustrates his point with an example of a runner with tibialis posterior tendonitis and a markedly medially deviated subtalar joint axis who presents in a motion control shoe. He points out that this patient would obviously need foot orthoses to continue to increase the external supination moment acting on the foot, more so than the shoe achieves alone.
When treating medial tibial stress syndrome in runners, what specific custom foot orthosis modifications have you found to be most helpful? What other treatment suggestions have you also found to be most effective at returning these patients to pain-free running?
Dr. Spooner cites the goals of his orthotics for medial tibial stress syndrome are to reduce the valgus bending moment through the tibial shaft and decrease the tensile force in the muscular and fascial attachments of the medial tibia. Accordingly, he usually incorporates a cast balanced inverted by about six degrees with a minimal arch fill and a medial heel skive, depending on patient weight. Dr. Spooner also uses a three to five mm polypropylene shell with an extrinsic rearfoot post of approximately four degrees. He advocates for a full-length topcover of three mm high-density ethylene vinyl acetate (EVA) and a four degree EVA forefoot varus extension under the first through the fourth rays.
In regard to adjunct treatment modalities, Dr. Spooner often recommends ice massage for medial tibial stress syndrome and line running drills if he notes that the patient has a crossover gait pattern.
Dr. Kirby and Dr. Williams also agree with the use of a medial heel skive. Dr. Kirby notes that he chooses a well-contoured and semi-rigid medial arch with a varus forefoot extension in a dual-density rearfoot-midsoled stability running shoe. For over two decades, he relates success with Plastazote® #3 shells, one-eighth inch neoprene topcovers and Korex forefoot varus extensions. For heavier runners, over 180 pounds, Dr. Kirby favors a motion control shoe with a polypropylene plate for added durability.
Dr. Kirby adds that patients should only wear these orthoses with a varus forefoot extension when running. If they use these orthoses during walking, a functional hallux limitus may result, according to Dr. Kirby.
Dr. Williams states he will often use a first ray cutout so any functional hallux limitus does not keep the patient pronated in midstance any longer than necessary.
Noting that he sees a fair amount of Division 1 NCAA runners with medial tibial stress syndrome, Dr. Williams notes most of these runners have minimal pronation excursion at the subtalar joint. In other words, he says these runners are “nearly rectus in resting calcaneal stance position.” Discussing a test previously described by Dr. Kirby, Dr. Williams says if these patients are unable to pronate more than one to two degrees in stance with their knees fully extended and locked, he will only post these patients no more than one to two degrees.
“If they have limited subtalar joint excursion and are close to a rectus heel in stance, … they will transmit a lot of forces upward through the tibia and this can lead to medial tibial stress syndrome,” notes Dr. Williams.
He adds that these patients often have limited ankle joint dorsiflexion as well. With this in mind, Dr. Williams will employ a 3 to 4 mm heel lift and post the runners no more than 1 to 2 degrees, usually with a medial heel skive.
Dr. Williams says increased fifth ray excursion is another common finding in runners with medial tibial stress syndrome and a three mm valgus wedge under the fourth and fifth rays may prove to be beneficial in these cases.
“A 3 mm valgus wedge in the forefoot under the fourth or fifth ray usually helps to significantly move plantar pressures toward the medial forefoot as the runners transition from midstance to propulsion,” adds Dr. Williams.
What orthosis shell material do you prefer in your custom foot orthoses for patients with running-related injuries, and why?
All of the panelists discuss use of polypropylene as a shell material. Dr. Kirby uses either polypropylene or Plastazote #3 (high density polyethylene foam) for runners, favoring Plastazote in lighter runners under 180 pounds. For heavier runners, he will choose polypropylene due to better resistance to deformation over time and the ability to adjust the thickness to account for flexibility.
Dr. Williams uses polypropylene almost exclusively. Most recently, he uses a PA11 material (Polyamide 11/Nylon 11, Go 4-D/HP). He feels the shell stiffness and material only matter if they match the foot type. Graphite is not Dr. William’s preferred shell material, however, due to excessive stiffness for most patients, necessitating aggressive arch fill for significant navicular drop.
Dr. Spooner cites polypropylene’s ability to be varied in thickness, allowing for manipulation of local stiffness characteristics. He continues to explain the convenience of adjustments chairside in that it is heat-moldable, easily grindable and resilient to fracture, creep and plastic deformation. Lastly, he notes that one can easily remove top covers from polypropylene without damaging the shell during refurbishing or adjustments.
Dr. Kirby is an Adjunct Associate Professor within the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University in Oakland, Calif. He is in private practice in Sacramento, Calif.
Dr. Spooner is in private practice at Peninsula Podiatry in Plymouth, United Kingdom.
Dr. Williams is a Past President and Fellow of the American Academy of Podiatric Sports Medicine. He is the Director of Breakthrough Sports Performance, LLC in Chicago. Dr. Williams has disclosed that he is the Medical Director for Go 4-D and a consultant for HP Fitstation.
This is an excellent Q & A article with sound and practical expert advice.