Key Insights On Orthotic Materials
In order to help bring orthotic therapy into sharper focus, some of the top thinkers on biomechanics share their insights on various orthotic materials. They discuss the importance of addressing the patient’s specific activity and pathology in arriving at an appropriate orthotic prescription, and offer their views and experiences on the efficacy of various orthotic materials. Without further delay, here’s what they had to say to questions posed by Robert Phillips, DPM.
Q: What type of feet do you feel almost always need rigid orthotics? What type of feet should never be put into a rigid orthotic?
A: Christopher E. Smith, DPM, notes that he uses rigid orthotics for the mobile flatfoot to the rigid cavus foot. As long as there is free range of motion in the subtalar and midtarsal joints and one has taken a good neutral cast, Dr. Smith says these patients can “tolerate both extremes of biomechanical pathology.”
If one captures the negative cast correctly and the lab does a good job with the positive cast correction, “a rigid material can be well tolerated by most foot types,” says Douglas Richie Jr., DPM. However, he believes that activity and pathology may have a greater role than foot type in determining the success of the rigid orthotic.
William Olson, DPM, agrees that how one uses the orthotic goes a long way toward determining a successful outcome. As an example, Dr. Olson notes that runners do very well in rigid orthotics as running involves a linear, repetitive motion. In these applications, he notes the enhanced durability of a rigid device provides “a consistent degree of correction over an extended period of time.”
While Dr. Smith likes devices to be rigid, he says he’ll use softer flexes for those who participate in linear sports and devices with frontal plane motion for side-to-side activities like court sports.
Indeed, when it comes to treating athletes who participate in high-velocity, complex motion sports such as basketball, soccer and tennis, Dr. Olson says they require “more compliance in the device.” He points out that the position of the foot varies significantly from foot strike to foot strike as it contacts the supporting surface.
Dr. Richie concurs. He has found that athletes who participate in sports such as tennis and volleyball emphasize lateral movement and ballistic muscular contractions so they do not tolerate rigid orthoses well. He also attributes this to the posture of the foot during these activities, noting that sports that require lateral movement and jumping place the foot in a plantarflexed position at the ankle more consistently than activities such as walking and running.
As a result of this increased plantarflexion of the ankle, Dr. Richie says rigid orthoses seem to irritate the medial band of the plantar fascia more so than the semi-rigid devices. However, he also emphasizes that the rigid restriction of frontal plane movement of the rearfoot upon the forefoot is “unnatural” in jumping and lateral movement activities. “This intolerance is almost universal among all foot types,” explains Dr. Richie.