• Changes in muscle activation [ Time Frame: over a three week period ] [ Designated as safety issue: No ]
  

• changes in functional range of motion [ Time Frame: over a 3 week period ] [ Designated as safety issue: No ]
  
• changes in function [ Time Frame: over a three week period ] [ Designated as safety issue: No ]
  

Muscle weakness is a common impairment following injury to a joint. Individuals with lateral ankle sprains have been shown to demonstrate weakness and inhibition of the fibularis longus and soleus muscles. Recently, changes in the positional alignment of the talus, tibia, and fibula have been implicated in a subpopulation of individuals with chronic ankle instability (CAI). Clinically this manifests as a decrease in the posterior glide of the talus and decreased dorsiflexion ROM. Another positional fault has been noted to occur between the distal tibiofibular joint. A subpopulation of individuals with a history of CAI have demonstrated a slight anterior displacement of the fibula relative to the tibia. The cause of the malpositioning is unknown, but manual therapeutic interventions may offer the ability to restore normal joint arthrokinematics and muscle function. It is unknown if the correction of this positional fault will have an effect on muscle inhibition about the ankle.

Since muscle inhibition is a neurological reflexive reaction, it is thought that traditional strengthening treatment techniques may not fully address this dysfunction. Manual therapeutic interventions can have dual effects on the neuromuscular system and restore normal joint arthrokinematics. Evidence suggests a joint manipulation is able to disinhibit or even facilitate local and distant muscles. This likely occurs due to the afferent response from the structures in and around the manipulated joint. Comprehensive treatment interventions which restore normal joint function, optimal motoneuron pool excitability, strength, and pain-free previous level of function need to be developed to prevent future dysfunction and osteoarthritis.

Currently no study has examined the effects of tibiofibular joint manipulation on the neuromuscular response of ankle musculature or the effects on range of motion and function. The purpose of this study is to examine the acute effects of a tibiofibular joint manipulation on the neuromuscular response of the fibularis longus and soleus muscles and to determine the long term effects on range of motion and function in individuals with CAI.

The first research question will address how a tibiofibular joint manipulation immediately affects the activation of the fibularis longus and soleus muscles. The second question will address how this joint manipulation affects range of motion and functional outcomes over a three week period. Changes in ankle dorsiflexion range of motion (ROM), navicular drop, Step Down Test, Balance Error Scoring System, and the Foot and Ankle Ability Measure (FAAM) will be used to determine if clinically significant changes occurred during the intervention period.