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Kimmery Migel and Erik Wikstrom

Clinical Scenario Approximately 3.1 million lateral ankle sprains (LASs) are diagnosed each year. 1 These seemingly innocuous injuries are significant as about 30% of all first-time patients with LAS develop chronic ankle instability (CAI). 2 CAI is a musculoskeletal condition characterized by

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Gregory M. Gutierrez and Thomas Kaminski

Lateral ankle sprains (LAS) are among the most common joint injuries, and although most are resolved with conservative treatment, others develop chronic ankle instability (AI). Considerable attention has been directed toward understanding the underlying causes of this pathology; however, little is known concerning the neuromuscular mechanisms behind AI. A biomechanical analysis of the landing phase of a drop jump onto a device that simulates the mechanism of a LAS may give insight into the dynamic restraint mechanisms of the ankle by individuals with AI. Furthermore, work evaluating subjects who have a history of at least one lateral ankle sprain, yet did not develop AI, may help elucidate compensatory mechanisms following a LAS event. Identifying proper neuromuscular control strategies is crucial in reducing the incidence of AI.

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Jonathan K. Holm, Jonas Contakos, Sang-Wook Lee and John Jang

This study investigated the energetics of the human ankle during the stance phase of downhill walking with the goal of modeling ankle behavior with a passive spring and damper mechanism. Kinematic and kinetic data were collected on eight male participants while walking down a ramp with inclination varying from 0° to 8°. The ankle joint moment in the sagittal plane was calculated using inverse dynamics. Mechanical energy injected or dissipated at the ankle joint was computed by integrating the power across the duration of the stance phase. The net mechanical energy of the ankle was approximately zero for level walking and monotonically decreased (i.e., became increasingly negative) during downhill walking as the slope decreased. The indication is that the behavior of the ankle is energetically passive during downhill walking, playing a key role in dissipating energy from one step to the next. A passive mechanical model consisting of a pin joint coupled with a revolute spring and damper was fit to the ankle torque and its parameters were estimated for each downhill slope using linear regression. The passive model demonstrated good agreement with actual ankle dynamics as indicated by low root-mean-square error values. These results indicate the stance phase behavior of the human ankle during downhill walking may be effectively duplicated by a passive mechanism with appropriately selected spring and damping characteristics.

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Rebecca L. Begalle, Meghan C. Walsh, Melanie L. McGrath, Michelle C. Boling, J. Troy Blackburn and Darin A. Padua

The ankle, knee, and hip joints work together in the sagittal plane to absorb landing forces. Reduced sagittal plane motion at the ankle may alter landing strategies at the knee and hip, potentially increasing injury risk; however, no studies have examined the kinematic relationships between the joints during jump landings. Healthy adults (N = 30; 15 male, 15 female) performed jump landings onto a force plate while three-dimensional kinematic data were collected. Joint displacement values were calculated during the loading phase as the difference between peak and initial contact angles. No relationship existed between ankle dorsiflexion displacement during landing and three-dimensional knee and hip displacements. However, less ankle dorsiflexion displacement was associated with landing at initial ground contact with larger hip flexion, hip internal rotation, knee flexion, knee varus, and smaller plantar flexion angles. Findings of the current study suggest that restrictions in ankle motion during landing may contribute to contacting the ground in a more flexed position but continuing through little additional motion to absorb the landing. Transverse plane hip and frontal plane knee positioning may also occur, which are known to increase the risk of lower extremity injury.

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Jack R. Engsberg, Richard E. A. Van Emmerik, Sandy A. Ross and David R. Collins

This investigation developed a measure of motor control at the ankle for persons with CP using relative phase. Twenty-nine subjects, 14 with spastic diplegia cerebral palsy (CP group) and 15 without disability (WD group) were tested once. Video data were collected as a seated subject performed four full range of ankle plantar and dorsiflexion movement tasks (right ankle, left ankle, ankles in-phase with each other, and ankles antiphase to each other) at four different frequencies (self-paced, 0.5, 0.75, 1.0 Hz). The relative phase measure was able to discern the differences between the two groups of children. The CP group had poorer motor control than the WD group, based upon the measure. Both groups had more difficulty performing the antiphase than the in-phase movements. The investigation adds to the body of knowledge in that the concept of relative phase was used as a measure of motor control at the ankle in persons with CP. Results indicated that the measure was adequately sensitive to quantify differences between a group with CP and a group without disability. Clinically the measure could eventually be used as both an assessment and outcome tool.

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Nick Caplan, Andrew Forbes, Sarkhell Radha, Su Stewart, Alistair Ewen, Alan St Clair Gibson and Deiary Kader

Context:

Ankle immobilization is often used after ankle injury.

Objective:

To determine the influence of 1 week’s unilateral ankle immobilization on plantar-flexor strength, balance, and walking gait in asymptomatic volunteers.

Design:

Repeated-measures laboratory study.

Setting:

University laboratory.

Participants:

6 physically active male participants with no recent history of lower-limb injury.

Interventions:

Participants completed a 1-wk period of ankle immobilization achieved through wearing a below-knee ankle cast. Before the cast was applied, as well as immediately, 24 h, and 48 h after cast removal, their plantar-flexor strength was assessed isokinetically, and they completed a single-leg balance task as a measure of proprioceptive function. An analysis of their walking gait was also completed

Main Outcome Measures:

Peak plantar-flexor torque and balance were used to determine any effect on muscle strength and proprioception after cast removal. Ranges of motion (3D) of the ankle, knee, and hip, as well as walking speed, were used to assess any influence on walking gait.

Results:

After cast removal, plantar-flexor strength was reduced for the majority of participants (P = .063, CI = −33.98 to 1.31) and balance performance was reduced in the immobilized limb (P < .05, CI = 0.84−5.16). Both strength and balance were not significantly different from baseline levels by 48 h. Walking speed was not significantly different immediately after cast removal but increased progressively above baseline walking speed over the following 48 h. Joint ranges of motion were not significantly different at any time point.

Conclusions:

The reduction in strength and balance after such a short period of immobilization suggested compromised central and peripheral neural mechanisms. This suggestion appeared consistent with the delayed increase in walking speed that could occur as a result of the excitability of the neural pathways increasing toward baseline levels.

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Ben Langley, Mary Cramp and Stewart C. Morrison

running shoes; (2) motion control running shoes will reduce the magnitude of ankle joint eversion compared with neutral and cushioned running shoes; and (3) cushioned running shoes will increase the magnitude of ankle joint eversion compared with neutral and motion control running shoes. Methods Based

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Ufuk Ersoy, Umut Ziya Kocak, Ezgi Unuvar and Bayram Unver

hypothesed that activating joint receptors of ankle joint through mobilization might result in an increase in the dorsiflexor muscles due to the AKR mechanism. Therefore, the aim of this study was to investigate the acute effect of talocrural joint mobilization on ankle dorsiflexor muscle strength in healthy

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Mary Hellen Morcelli, Dain Patrick LaRoche, Luciano Fernandes Crozara, Nise Ribeiro Marques, Camilla Zamfolini Hallal, Mauro Gonçalves and Marcelo Tavella Navega

gait speed. 7 , 8 Poor lower limb strength has been associated with slow gait speed and the likelihood of falling, making it an important predictor of functional status in older adults. 9 – 12 The association exists because joint torques at the hip, knee, and ankle are summed in a coordinated fashion

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Kimberly Somers, Dustin Aune, Anthony Horten, James Kim and Julia Rogers

Possessing adequate ankle dorsiflexion (DF) range of motion (ROM), or, by extension, improving ROM when deficient, has the potential to prevent ankle and knee injuries that may result in lower-extremity (LE) dysfunction. 1 , 2 An inverse relationship was observed between DF ROM and ankle injuries