In-shoe plantar pressures within ankle-foot orthoses: implications for the management of achilles tendon ruptures.
Kearney RS., Lamb SE., Achten J., Parsons NR., Costa ML.
BACKGROUND: Advances in the management of Achilles tendon rupture have led to the development of immediate weightbearing protocols. These vary regarding which ankle-foot orthoses (AFOs) are used and the number of inserted heel wedges used within them. PURPOSE: This study was conducted to evaluate plantar pressure measurements and temporal gait parameters within different AFOs, using different numbers of heel wedges. STUDY DESIGN: Controlled laboratory study. METHODS: Fifteen healthy participants were evaluated using 3 different AFOs, with 4 different levels of inserted heel wedges. Therefore, a total of 12 conditions were evaluated, in a sequence that was randomly allocated to each participant. Pressure and temporal gait parameters were measured using an in-shoe F-Scan pressure system, and range of movement was measured using an electrogoniometer. RESULTS: Ankle-foot orthoses that were restrictive in design, combined with a higher number of inserted heel wedges, reduced forefoot pressures, increased heel pressures, and decreased the amount of time spent in the terminal stance and preswing phase of the gait cycle (P = .029, .002, and .001). CONCLUSION: The choice of AFO design and the number of inserted heel wedges have a significant effect on plantar pressure measurements and temporal gait parameters. The implications of these changes need to be applied to the clinical management of acute Achilles tendon ruptures. This clinical management requires a balance between protected weightbearing and functional loading, requiring further research within a clinical context. CLINICAL RELEVANCE: The biomechanical data from this research imply that a carbon-fiber AFO, with 1 heel raise, protects against excessive dorsiflexion while facilitating the restoration of near-normal gait parameters. This could lead to an accelerated return to function, avoiding the effects of disuse atrophy. This is in contrast to the rigid rocker-bottom AFO design with a greater number of heel-wedge inserts. However, research within a clinical context would be required to ascertain if these biomechanical advantages translate into a functional benefit for patients. The results should also be considered in relation to the amount of force a healing Achilles tendon can withstand.