A novel dynamic ankle-supinating device

Ankle taping can reduce external ankle joint moments during drop landings on a tilted surface

Ankle taping is commonly used to prevent ankle sprains. However, kinematic assessments investigating the biomechanical effects of ankle taping have provided inconclusive results. This study aimed to determine the effect of ankle taping on the external ankle joint moments during a drop landing on a tilted surface at 25°. Twenty-five participants performed landings on a tilted force platform that caused ankle inversion with and without ankle taping. Landing kinematics were captured using a motion capture system. External ankle inversion moment, the angular impulse due to the medio-lateral and vertical components of ground reaction force (GRF) and their moment arm lengths about the ankle joint were analysed. The foot plantar inclination relative to the ground was assessed. In the taping condition, the foot plantar inclination and ankle inversion angular impulse were reduced significantly compared to that of the control. The only component of the external inversion moment to change significantly in the taped condition was a shortened medio-lateral GRF moment arm length. It can be assumed that the ankle taping altered the foot plantar inclination relative to the ground, thereby shortening the moment arm of medio-lateral GRF that resulted in the reduced ankle inversion angular impulse.

Minimum reporting standards for copers in chronic ankle instability research

Lateral ankle sprains (LASs) are among the most common sports-related injuries and a high percentage of individuals who sprain their ankle go on to develop chronic ankle instability (CAI). The condition of CAI is often classified as having pain, loss of function, and a restriction of, or failure to, return to levels of previous activity. Historically, uninjured healthy controls are used as a comparison group to study the biomechanical and neuromuscular consequences of CAI. However, this model is not ideal to determine why a portion of the population experiencing an ankle sprain does not recover. A more appropriate comparison may be individuals who had an ankle sprain, and thus the exposure, but did not go on to develop CAI (i.e., copers). Thus, the purpose of this review was to determine the existing discrepancies and common standards in definitions of, terminology used for, and the inclusionary/exclusionary criteria used to describe copers within the CAI literature. Multiple databases were searched by keywords and specific authors. Potential studies were screened independently by both authors. Inclusion criteria consisted of an explicit definition of copers and explicit inclusionary/exclusionary criteria. A total of 21 studies were included in the current study and had four outcomes extracted: (1) the definition of copers; (2) the terminology used; (3) specific inclusionary/exclusionary criteria; and (4) injury characteristics of the copers. Based on the included operational definitions, it is recommend that future operational definitions of copers include three key components: (1) an initial LAS; (2) subsequent lack of CAI symptoms (i.e., no complaints of disability or giving way); and (3) a time since injury component. The term coper was overwhelming used within the existing literature (n = 15) and is thus recommended to be used in future studies when describing individuals who have suffered an LAS but failed to develop CAI. Minimal inclusionary criteria should consist of three things: (1) an initial LAS severe enough to warrant either the use of a protective device (e.g., ankle brace) for at least 1 week or immobilization and/or non-weight bearing for at least 3 days, or both; (2) a return to at least moderate levels of weight-bearing physical activity for at least 12 months without recurrent injury, episodes of giving way, and/or feelings of instability; and (3) minimal, if any, level of self-reported disability. Acute head and/or lower extremity injuries that occurred ≤3 months prior to testing, a history of ankle fractures and/or surgeries, and the presence of pain (constant or intermittent) should be used as minimal exclusionary criteria in future investigations dealing with copers. Finally, at least seven items should be reported to better contextualize copers across investigations. These items should include the initial mechanism of injury, the presence of mechanical laxity, number of days immobilized and/or non-weight bearing after the initial ankle sprain, time since the latest ankle sprain, percentage of coper participants with a recurrent ankle sprain or giving way episode, current physical activity levels, and whether copers attended formal rehabilitation for their involved ankle.

Foot structure and muscle reaction time to a simulated ankle sprain

CONTEXT

Foot structure has been shown to affect aspects of neuromuscular control, including postural stability and proprioception. However, despite an association between pronated and supinated foot structures and the incidence of lateral ankle sprains, no one to our knowledge has measured muscle reaction time to a simulated ankle-sprain mechanism in participants with different foot structures.

OBJECTIVE

To determine whether pronated or supinated foot structures contribute to neuromuscular deficits as measured by muscle reaction time to a simulated ankle-sprain mechanism.

DESIGN

Cross-sectional study.

SETTING

University biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty volunteers were categorized into 3 groups according to navicular-drop-height measures. Ten participants (4 men, 6 women) had neutral feet (navicular-drop height = 5-9 mm), 10 participants (4 men, 6 women) had pronated feet (navicular-drop height ≥ 10 mm), and 10 participants (4 men, 6 women) had supinated feet (navicular-drop height ≤ 4 mm).

INTERVENTION(S)

Three perturbations on a standing tilt platform simulating the mechanics of an inversion and plantar-flexion ankle sprain.

MAIN OUTCOME MEASURE(S)

Muscle reaction time in milliseconds of the peroneus longus, tibialis anterior, and gluteus medius to the tilt-platform perturbation.

RESULTS

Participants with pronated or supinated foot structures had slower peroneus longus reaction times than participants with neutral feet (P = .01 and P = .04, respectively). We found no differences for the tibialis anterior or gluteus medius.

CONCLUSIONS

Foot structure influenced peroneus longus reaction time. Further research is required to establish the consequences of slower peroneal reaction times in pronated and supinated foot structures. Researchers investigating lower limb muscle reaction time should control for foot structure because it may influence results.

Chronic ankle instability: diagnosis and treatment

BACKGROUND

Chronic ankle instability (CAI) is a very common injury but still remains an area of debate.

QUESTIONS

This review aims to define the current diagnosis and treatment of persons with CAI.

METHODS

A PubMed (MEDLINE) search of the years 2010 and 2011 (1 January 2010 to 15 July 2011) was performed using three keywords: ankle and chronic and instability. The number of articles in English language that was identified was 57.

RESULTS

Low reliability has been found in effectively testing CAI in a clinical setting. No single force-plate measure is very effective in predicting if an individual had CAI or not. Availability of a nonradiographic device (ankle arthrometer) to measure ankle instability could improve diagnostic accuracy and facilitate decision making in patients with CAI. The sensitivity of magnetic resonance imaging (MRI) may not be adequate to detect lesions in these patients before surgery. In a symptomatic patient, negative results on MRI must be viewed with caution and an arthroscopy may still be required for a definitive diagnosis and treatment. Conservative treatment (rehabilitation, taping, brace) may reduce the occurrence of recurrent ankle sprains and may be effective in managing CAI. In patients with CAI, strengthening of the muscles around the ankle with well-planned proprioceptive exercises helped the patients return to normal living and sports activities, and prevents unnecessary surgery, especially in cases with functional instability. There is no consensus regarding optimum surgical treatment for CAI, but all of them often have good results.

CONCLUSIONS

Conservative treatment of patients with CAI must be the first-line therapy. Surgical treatment must be indicated only when conservative treatment fails.

Examining neuromuscular control during landings on a supinating platform in persons with and without ankle instability

BACKGROUND

Ankle instability is a costly public health concern because of the associated recurrent sprains. It is evident there are neuromuscular control deficits predisposing these individuals to their ankle "giving way." Individuals with a history of lateral ankle sprain, who did not develop instability, may hold the key to understanding proper neuromuscular control after injury.

HYPOTHESES

On the basis of previous research, the authors hypothesized that individuals with ankle instability would demonstrate reduced peroneal activation, causing a more inverted position of the ankle, before and after landing.

STUDY DESIGN

Controlled laboratory study.

METHODS

This study aimed to evaluate preparatory and reactive neuromuscular control when landing on a custom-designed ankle supinating device in individuals with ankle instability (AI), individuals with a history of lateral ankle sprains without instability (LAS), and uninjured controls (CON). Forty-five participants (15 per group) were asked to land on a device built to simulate the mechanism of a lateral ankle sprain (supination) while kinematics and muscle activity of the lower extremity were monitored.

RESULTS

Contrary to our hypotheses, the AI group displayed significantly increased preparatory (P = .01) and reactive (P = .02) peroneal activation, while the LAS group demonstrated a trend toward increased preparatory tibialis anterior muscle activation (P = .07), leading to a decreased plantar flexion of the ankle at landing.

CONCLUSION

The AI group was likely acting in a protective fashion to a potentially injurious situation, indicating these individuals can activate the peroneals if needed. The LAS group's strategy may be a safer strategy in that a less plantar-flexed position of the ankle is more close-packed and stable. Further, it appears the long-latency response of the peroneals may be enhanced in these individuals, which indicates motor learning at the supraspinal level to promote dynamic restraint.

CLINICAL RELEVANCE

Individuals with AI can increase peroneal activation when necessary to dynamically stabilize the ankle, indicating the potential for training/rehabilitation. Further, the LAS group may deploy a different control strategy after injury to protect the ankle from subsequent sprains, which deserves investigation during activities of daily living. A greater understanding of these strategies will lead to the development of more appropriate treatment paradigms after injury to minimize the incidence of instability.