A study investigating the effects of three types of orthoses on gait biomechanics in individuals with posterior tibial tendon dysfunction (PTTD) found that custom orthoses may be more suitable than prefabricated to decrease the pathological biomechanical outcomes in PTTD. The authors cautioned, however, that custom orthoses may cause unwanted collateral biomechanical effects at the knee.
The 14 participants had painful stage 1 or 2 PTTD based on Johnson and Strom’s classification. Quantitative gait analysis of the affected limb was performed in four conditions: shoes only (Shoe), prefabricated foot orthosis (PFO), neutral custom FO (CFO) and custom varus FO (CVFO) with a 5 degree medial wedge and a 4mm medial heel skive. A curve analysis assessed differences in lower-limb joint motion, joint moments, and muscle activity over the stance phase of gait across conditions.
The data indicated decreased hindfoot eversion angles, decreased ankle inversion moments, and increased ankle eversion moments with the CFOs and CVFOs compared to the Shoe and PFO conditions. CFOs and CVFOs induced an increased knee adduction moment compared to Shoe. No changes in hip kinematics and kinetics or in EMG activity of tested muscles were observed between conditions.
The researchers concluded that decreased ankle inversion moments during the stance phase could explain why custom orthoses are effective at reducing pain in PTTD patients.
The study, “Biomechanical effects of three types of foot orthoses in individuals with posterior tibial tendon dysfunction,” was published in Gait & Posture.
