Posts in orthotics
Orthotics Impact on Leg Mechanics

The use of foot orthotics are commonly prescribed for many lower quarter conditions including running injuries, foot and ankle pain, and even low back pain.  As we have described in previous posts off the shelf orthotics perform as well as more expensive custom orthotics, but overall their impact on many conditions is limited.  When compared to more active approaches including Physical Therapy and exercise, orthotics fall short of manufacturer's and clinician's promises of pain relief and improved function.  

A recent study out of the University of Wisconsin examined the impact of off the shelf orthotics on running mechanics (O'Conner et al. JOSPT. 2016).  Authors studied 31 recreational runners in a biomechanics laboratory while running with or without a foot orthotic.  In particular, the authors were interested in the amount of dynamic foot motion at the heel and mid foot during the stance phase of running.  Runners were then grouped based on the amount of motion in their feet during running.  They hypothesized that runners with the greatest amount of motion may benefit most from the orthotic.  The results of this study show that orthotics did not significantly impact motion at the hip or knee and thus the use of orthotics based on a patients degree of foot and ankle motion is not supported.

Athletes are advised to understand the limitations of orthotics to change lower quarter running mechanics and instead work with a local Physical Therapist to correct these running mechanics.

Weakened Foot Strength and Orthotic Use in Patients with Heel Pain

In our previous posts we have documented the weakness and atrophy of the foot's "core" muscles among patients with heel pain.   Heel pain is one of the most common foot and ankle diagnoses we see in our Boulder Physical Therapy Practice.  This condition is commonly treated with manual therapy and exercises targeting the lower quarter.  A targeted area for exercise involves the foot's core muscles which contribute to stability and function of our arch.  Without adequate strength and control of the arch we are more at risk for conditions such as heel pain and plantar fasciitis.  Recent research highlights the importance of these muscles and the negative impact foot orthoses may have on their function. 

McClinton and colleagues studies 27 patients with heel pain compared to matched peers who ddi not have any heel pain (JOSPT 2016).  Participants' foot strength was tested using two clinical tests for foot "core" strength.  Not surprisingly, the patients with heel pain had significantly less foot strength than their asymptomatic peers.  Interestingly, longer use of foot orthoses was associated with lower performance on these strength measurements.   Stabilization of the arch with foot orthotics may weaken the foot's core muscles because they prevent these muscles from performing their natural function.  

Patient's are encouraged to contact their local PT on the most appropriate treatments for their heel and foot pain.  

Foot Orthotics Impact on Running Economy

The human foot is a remarkable structure of 26 bones and 30+ joints integral to both walking and running.  The foot must be able to both flatten (pronate) and absorb the forces of the body, as well as, become rigid (supinate) in preparation for propelling us forward.  This balance of mobility and stability is accomplished through the coordination of forces and muscular contractions across the ankle and foot.  The "core" of the foot made up of small muscles in the arch is a key structure for optimal functioning of the foot and kinetic chain.  Authors believe the absorption and production of energy during walking and running conserves energy during the gait cycle making us more efficient in our daily movements and athletic adventures.   

Previous researchers have found up to 17% of the energy absorbed by the foot in stance is immediately returned to foot at push off during running (Ker et al. 1987).  More recently authors have corroborated this data and reported on the energy sparing effects of our longitudinal arch (Stearne et al. Nature. 2015).  Authors reported greater metabolic costs and worse running economies in runners with stiffer arch supports and orthotics.  It is believed the orthotics and arch supports restricted the ability of the arch to absorb and release energy during gait cycling placing a higher metabolic demand on the runner.  The orthotics likely also weaken the key intrinsic foot muscles of the arch.

Previous research has not supported the use of more expensive, customized arch supports (orthotics) on pain and injury over less expensive, off the shelf orthotics.  This article calls into question the ability of these orthotics and inserts to improve running economy and performance.  Runners are advised to choose a comfortable, self selected running shoe and avoid expensive inserts.   

Foot Orthotics and Overuse Injury

Customized foot orthotics based off a clinical examination, plaster or foam cast have been utilized for decades in order to treat overuse injuries of the foot, ankle, knee, hip and even spine.  These orthotics are usually not covered by insurance and usually run into the hundreds of dollars compared to an off the shelf model.  Many businesses have opened up lately specializing in the prescription and fabrication of orthotics for these conditions claiming correction of the foot and ankle can change the mechanics up the kinetic chain.  Up to this point, with a few patient exceptions, customized orthotics have not been proven more effective than cheaper off the shelf orthotics.  

This blog has previously posted on many aspects of achilles tendinopathy.  A recent article examined in the British Journal of Sports Medicine randomized 140 patients with achilles tendinopathy to either a sham orthotic or a customized orthotic (Munteanu et al. 2015).  In addition, both groups were given eccentric calf strengthening exercises.  The patients were followed over a total of 12 months.  Authors noted improvement in both groups, but no difference between groups at either short or long term functional or clinical outcomes.    It appears the orthotic did not improve symptoms or function above or beyond improvements noted with the eccentric exercise.  

In short, consistent with prior research, customized orthotics are not more effective than other interventions for overuse injuries of the lower extremity.  Future research should attempt to identify any individual factors that may indicate a need for an orthotic intervention.