The investigator's purpose is to compare the effects of talocrural joint mobilization with movement versus thrust mobilization on functional performance in subjects reporting chronic ankle instability (CAI).

Joint mobilizations are reported to increase range of motion (ROM), postural control and proprioception, and decrease pain in individuals with CAI. However, there is no research comparing the effects of mobilization with movement (MWM) versus thrust mobilization (TM) directed at the talocrural joint on functional performance in this population.

Inclusion and exclusion criterion have been established utilizing the International Ankle Consortium guidelines. Using a convenience sampling, participants will be randomized into the MWM or TM group.

The MWM group will receive manual therapy with the following protocol: the participant will be relaxed and standing in a staggered stance with the involved foot on an eight inch step and both feet facing forward . The clinician will be positioned in front of the participant's leg and a non-elastic belt will be placed around the distal leg of the participant and the clinician's pelvis. The clinician will then apply a sustained posteroanterior glide to the tibia through the belt by leaning backwards, while stabilizing the fixed talus and forefoot with both hands. The participant will perform a slow lunge until the end range of motion without their heel lifting off the ground. The belt will be kept perpendicular to the tibia throughout the movement and 2 sets of 10 repetitions will be applied.

The talocrural joint TM will be a high velocity low amplitude manual therapy technique. This technique will be applied with the participant in the supine position on a plinth. The clinician grasps the foot with one hand with the fifth finger contacting the anterior surface of the ankle at the talus. The other hand reinforces the contact points and both thumbs are placed on the sole of the participant's foot. The clinician gives slight caudal traction focused on the talocrural joint with the ankle dorsiflexed and everted. The therapist then applies a high-velocity thrust distraction technique to the talocrural joint. Only one thrust will be applied and no audible cavitation is required. Each manual therapy technique will be performed once.

An examiner, who is blinded to involved limb and group allocation, will perform a baseline, immediate follow-up, and one-week follow-up examination of range of motion and functional performance. The participants will complete subjective outcome measures at baseline, immediately post intervention, and at 1 week post intervention including the Foot and Ankle Ability Measurement (FAAM), FAAM-Sport, and the Cumberland Ankle Instability Tool (CAIT). Participants will also complete baseline, immediate follow-up, and one-week follow up assessments of the Multiple Hop Test (MHT), three directions of the Star Excursion Balance test (SEBT), and weight bearing lunge test (WBLT).

Data analysis will be performed using International Business Machines Statistical Package for the Social Sciences (SPSS). Alpha level will be set p<0.05. Expecting to utilize separate 2 x 2 repeated measures analysis of variance (ANOVA) to assess changes in the FAAM, FAAM-Sport, CAIT, MHT, WBLT, and three directions of the SEBT.

Criteria:

As adapted from the position statement from the International Ankle Consortium.

Inclusion Criteria:

• 18-35 years of age
• A history of at least 1 significant ankle sprain (The initial sprain must have occurred at least 12 months prior to study enrollment, associated with inflammatory symptoms (pain, swelling, etc), created at least 1 interrupted day of desired physical activity)
• The most recent injury must have occurred more than 3 months prior to study enrollment.
• A history of the previously injured ankle joint "giving way" and/or recurrent sprain and/or "feelings of instability."
• Cumberland Ankle Instability Tool (CAIT) < 24
• Foot and Ankle Ability Measure (FAAM)42: ADL scale < 90%, Sport scale < 80%

Exclusion Criteria:

• A history of previous surgeries to the musculoskeletal structures (i.e., bones, joint structures, nerves) in either limb of the lower extremity.
• A history of a fracture in either limb of the lower extremity requiring realignment
• Acute injury to musculoskeletal structures of other joints of the lower extremity in the previous 3 months, which impacted joint integrity and function (i.e., sprains, fractures) resulting in at least 1 interrupted day of desired physical activity