Biomedical subjects

Carrie L Docherty

Publications and source records attributed to Carrie L Docherty.

10 recordsLinked to original sources

PubMed2006

Contralateral force sense deficits are related to the presence of functional ankle instability.

Residual symptoms that often follow lateral ankle sprains can lead to functional ankle instability. Proprioceptive deficits have been identified as one factor that may contribute to the presence of functional ankle instability. Sixty participants were recruited to participate in the study. Seven questions were used to determine the presence of functional ankle instability in each participant. A point was added for each "yes" response to produce an index that represents an interval data scale of functional ankle instability. Contralateral force sense and active joint reposition sense were measured in all participants. Pearson product moment correlations were calculated to determine the relationship between functional ankle instability and force sense and active joint reposition sense. We found a significant relationship with force sense and functional ankle instability. Specifically, force sense variable error at both test forces (10 and 30% of maximal voluntary isometric contraction) were positively correlated to the presence of functional ankle instability, r=0.26; p<or=0.05 and r=0.25; p<or=0.05, respectively. All other force sense correlations were not statistically significant. No significant correlations were identified between active joint reposition sense and functional ankle instability. This study indicates that participants with functional ankle instability have deficits in low load force sense, but not active joint reposition sense.

Adolescent↗

PubMed2006

Postural control deficits in participants with functional ankle instability as measured by the balance error scoring system.

OBJECTIVE: To determine if postural control deficits are present in participants with functional ankle instability (FAI) as measured by the Balance Error Scoring System (BESS). DESIGN AND SETTING: We used a between-groups design to assess postural control. All testing was conducted in a university athletic training facility. PARTICIPANTS: Sixty collegiate Division I athletes were included in this study. Thirty participants had functional ankle instability and thirty participants had no history of ankle injuries. MAIN OUTCOME MEASUREMENTS: Postural control was measured using the BESS. The BESS test battery requires participants to stand unsupported on two different surfaces (firm and foam) in three different stances (double, single, and in tandem). Each condition lasted 20 seconds. The number of errors were calculated for each individual condition and then summed to produce a total BESS score. RESULTS: We found a significant group by condition interaction (F5,290 = 5.12, P < 0.001) and significant main effects for group (F1,58 = 16.01, P < 0.001) and condition (F5,290 = 228.88, P < 0.001). Post hoc analyses revealed that subjects with functional ankle instability scored more errors (poorer balance) on the single stancefirm condition (2.9 +/- 2.1 versus 1.6 +/- 1.3 errors), tandem stancefoam condition (4.3 +/- 2.4 versus 2.7 +/- 1.6 errors), single stancefoam condition (7.0+/-1.6 versus 5.6 +/- 1.8 errors), and total BESS score (15.7 +/- 6.0 versus 10.7 +/- 3.2). CONCLUSIONS: Postural control deficits were identified in participants with functional ankle instability using the BESS. These deficits could be a contributing factor to the repeated episodes of instability and giving way that often occurs following an inversion ankle sprain. These results suggest the BESS, traditionally used for monitoring recovery from mild head injury, may also be useful in screening athletes for postural deficits following lower extremity injury.

Adolescent↗

PubMed2005

Arthrogenic muscle inhibition in the leg muscles of subjects exhibiting functional ankle instability.

BACKGROUND: Functional ankle instability or a subjective report of ;;giving way'' at the ankle may be present in up to 40% of patients after a lateral ankle sprain. Damage to mechanoreceptors within the lateral ankle ligaments after injury is hypothesized to interrupt neurologic feedback mechanisms resulting in functional ankle instability. The altered input can lead to weakness of muscles surrounding a joint, or arthrogenic muscle inhibition. Arthrogenic muscle inhibition may be the underlying cause of functional ankle instability. Establishing the involvement of arthrogenic muscle inhibition in functional ankle instability is critical to understanding the underlying mechanisms or chronic ankle instability. The purpose of this investigation was to determine if arthrogenic muscle inhibition is present in the ankle joint musculature of patients exhibiting unilateral functional ankle instability. METHODS: Twenty-nine subjects, 15 with unilateral functional ankle instability and 14 healthy control subjects, consented to participate. Bilateral soleus, peroneal, and tibialis anterior H-reflex and M-wave recruitment curves were obtained. Maximal H-reflex and maximal M-wave values were identified and the H:M ratios were calculated for data analysis. Separate 1 x 2 ANOVA were done for both the functional ankle instability and control groups to evaluate differences between limbs on the H:M ratios. Bonferroni multiple comparison procedures were used for post hoc comparisons (p < or = 0.05). RESULTS: The soleus and peroneal H:M ratios for subjects with functional ankle instability were smaller in the injured limb when compared with the uninjured limb (p < 0.05). No limb difference was detected for the tibialis anterior H:M ratio in the functional ankle instability group (p = 0.904). No side-to-side differences were detected for the H:M ratios in patients reporting no history of ankle injury (p > 0.05). CONCLUSIONS: Depressed H:M ratios in the injured limb suggest that arthrogenic muscle inhibition is present in the ankle musculature of patients exhibiting functional ankle instability. Establishing and using therapeutic techniques to reverse arthrogenic muscle inhibition may reduce the incidence of functional ankle instability.

Adult↗

PubMed2005

Functional-Performance Deficits in Volunteers With Functional Ankle Instability.

Context: Although functional-performance tests are dynamic measures used to assess general lower body function, studies investigating these tests for ankle instability have yielded conflicting results.Objective: To determine if a relationship exists between a measure of functional ankle instability and deficits in functional performance.Design: A case-control study correlating subject performance on a set of lower extremity functional-performance tests with a measure of ankle instability.Setting: University athletic training research laboratory.Patients or Other Participants: We recruited 60 participants (43 females, 17 males, age = 22.4 +/- 4.9 years, height = 169.9 +/- 9.7 cm, mass = 72.6 +/- 16.3 kg; 42 injured, 18 uninjured) to participate in the study. Six questions were used to determine if functional ankle instability was present in each participant. A point was added for each yes response to produce an index that represents a continuous variable of functional ankle instability.Main Outcome Measure(s): Four unilateral hopping tests were used in this study: figure-of-8 hop, side hop, up-down hop, and single hop. For the first 3 tests, the total time was recorded with a handheld stopwatch to the nearest 0.01 second; for the single hop-for-distance test, the distance was recorded to the nearest 0.01 m. Correlations were computed with the functional ankle instability index and each of the 4 functional-performance tests.Results: No relationship was revealed between the functional ankle instability index and single hop for distance or up-down hop, with r values of -.008 and .245, respectively. A significant relationship was found between the functional ankle instability index and the side hop (r = .35, P </= .01) and the figure-of-8 hop (r = .31, P </= .02).Conclusions: A positive relationship existed between functional ankle instability and performance deficits on the side hop and figure-of-8 hop. Conversely, a relationship did not exist between functional ankle instability and frontal-plane functional-performance activities.

Journal Article↗

PubMed2004

Bracing and rehabilitation--what's new.

Based on the recent evidence, ankle bracing and taping do appear to have positive effects on ankle support. For example, both bracing and taping restrict inversion range of motion, with tape and stirrup-style braces providing the best support. Although exercise reduces this restriction, the range remains consistent with levels considered to be within the normal range. Ankle supports also appear to improve the strength of the muscular response to perturbation, potentially providing a stronger muscular contraction. In contrast, ankle supports fail to improve the neuromuscular response time to unexpected perturbations. Thus, it appears that the stronger response may occur too slowly to protect the joint. This slowness of the neuromuscular response, however, may be offset by the support's ability to slow the inversion motion. The slowing of inversion appears to allow the neuromuscular system to respond at or before the point of ligament damage. Finally, ankle supports appear to improve balance only in individuals with previously injured ankles. This suggests that supports may have a selective effect in protecting injured but not uninjured individuals. Despite these positive effects, some cautions should be emphasized. First, most of the studies cited have been performed in the laboratory setting with joint velocities and loads much below what are encountered in the athletic and daily activities. Whether tape and braces can maintain their effectiveness under the more extreme conditions of functional activities remains unclear. Additionally, some evidence suggests that ankle supports may transfer loads to other joints putting them at risk for injury. Thus, further study is needed to determine the risk-to-benefit ratio of ankle supports. Finally, much of the research presented has been done only on uninjured ankles. Based on the current evidence, it seems possible that the effectiveness of ankle supports may differ depending on the population, and it seems clinically important to know whether we can expect the same results for injured and uninjured ankles. Proper and early rehabilitation is important in preventing residual ankle symptoms. Reports indicate that up to 73% of people who sustain a lateral ankle sprain have recurrent sprains, but it is unknown how many of these participants partake in rehabilitation. Proper immobilization and acute care of the injured ankle is imperative. An immobilization boot or strapping that can be removed during early non-weight bearing exercises seems to be most effective. Strength and balance training of the uninjured contralateral limb can be used to assist reaching full recovery in a shorter period of time. Functional exercises can also be performed earlier in the rehabilitation process by reducing the gravitational forces so patients can perform in a pain-free range and still receive the benefits of early activity. Evidence shows that daily ankle disk training assists in preventing ankle sprains, and is a relatively inexpensive and easy alternative to traditional rehabilitation protocols.

Ankle Injuries↗

PubMed2004

Relationship between two proprioceptive measures and stiffness at the ankle.

Previous research has investigated the role of proprioception and stiffness in the control of joint stability. However, to date, no research has been done on the relationship between proprioception and stiffness. Therefore, the purpose of this study was to determine the relationship between force sense, joint reposition sense, and stiffness at the ankle. A heterogeneous sample was obtained for this study; 20 of the 40 participants had a history of ankle sprains, and 13 of the 20 had been diagnosed by a physician (two mild ankle sprains, seven moderate sprains, four severe sprains). All subjects were asymptomatic and active at the time of the study. Active joint reposition sense was measured using a custom-built ankle goniometer, force sense was measured unilaterally and contralaterally with a load cell, and ankle muscle stiffness was measured via transient oscillation using a custom-built inversion-eversion cradle. We found no significant correlations between stiffness and joint reposition sense, with values of r ranging from 0.01 to 0.21. Significant correlations were found between stiffness and force sense. Specifically, contralateral force sense reproduction was significantly correlated to stiffness in the injured or "involved" ankle (r's ranging from 0.47 to 0.65; P< or =0.008). Whether the decreased ability to appropriately sense force (increased error) sends information to the central nervous system to increase muscle stiffness in response to an unexpected loss of stability, or whether these two phenomena function independently and both change concurrently as a result of injury to the system requires further investigation.

Adult↗

PubMed2002

Chronic Ankle Instability Does Not Affect Lower Extremity Functional Performance.

OBJECTIVE: To determine if functional performance is impaired in individuals with self-reported chronic ankle instability. DESIGN AND SETTING: We used a between-groups design to assess 3 functional variables. All data were collected at a Division III college and a military academy. Before testing, all subjects performed a 5-minute warm-up, followed by a series of stretches for the lower extremity muscles. Subjects then performed cocontraction, shuttle run, and agility hop tests in a counterbalanced fashion. Three trials for each functional test were completed and averaged for analysis. SUBJECTS: Twenty men with a history of at least 1 significant ankle sprain and episodes of at least 1 repeated ankle injury or feelings of instability or "giving way" were compared with 20 men with no prior history of ankle injury. Subjects were matched by age, height, weight, and activity level. MEASUREMENTS: Time to completion was measured in seconds for the cocontraction and the shuttle run tests. The agility hop test was measured on an error point scale. RESULTS: Using 3 separate, independent, 2-tailed t tests, we found no significant difference between groups for the cocontraction (P =.452), shuttle run (P =.680), or agility hop (P =.902) tests. CONCLUSIONS: Chronic ankle instability is a subjectively reported phenomenon defined as the tendency to "give way" during normal activity. Although athletes commonly complain of subjective symptoms associated with chronic ankle instability, our findings suggest that these symptoms do not negatively influence actual functional performance. Future researchers should evaluate other, more demanding functional-performance tests to further substantiate these findings.

Journal Article↗

PubMedDate not supplied

Development and reliability of the ankle instability instrument.

CONTEXT: Functional ankle instability has been defined in a variety of ways. Factors that are frequently used in this definition include a history of a severe ankle sprain, a history of multiple ankle sprains, and a recurrent feeling of instability or "giving way." With all the variations in defining functional ankle instability, it becomes increasingly important to develop a more consistent framework for assessing this instability. OBJECTIVE: To develop a new ankle instability assessment tool, the Ankle Instability Instrument, and evaluate the reliability of this instrument. DESIGN: Test-retest reliability was evaluated using intraclass correlation coefficients (2,1) for each item, each factor, and the total score between test days 1 and 2. Cronbach alpha was calculated to estimate internal consistency of the 12 items. SETTING: Classrooms, offices, athletic fields, and private residences. PATIENTS OR OTHER PARTICIPANTS: College students (29 males, 72 females, age = 20.7 +/- 2.7 years), including 73 (72%) with and 28 (28%) without a history of ankle injury. MAIN OUTCOME MEASURE(S): Subjects were asked to complete the Ankle Instability Instrument on 2 occasions approximately 1 week apart. RESULTS: An exploratory factor analysis of the Instrument produced 3 factors and reduced it from 21 to 12 items. The factors accounted for 32.3%, 10.7%, and 7.0% of the variance, respectively. Together, these factors accounted for 50.0% of the variance in the responses to the Instrument. Test-retest reliability ranged from .70 (SEM = 0.28) to .98 (SEM = 0.06) for the individual items and .95 (SEM = 1.85) for the Instrument overall. The Cronbach alpha coefficient was .92 for factor 1 (severity of initial ankle sprain), .87 for factor 2 (history of ankle instability), .81 for factor 3 (instability during activities of daily life), and .89 for the Instrument overall. CONCLUSIONS: The creation of the Ankle Instability Instrument is a first step in recognizing a more objective way of identifying patients suffering from functional ankle instability. The high reliability we found shows that self-reporting of ankle symptoms is a feasible, appropriate way to obtain information on the presence of instability symptoms. Additionally, through this preliminary study, we found 3 factors that represent unique and important components of functional ankle instability. Clinicians and researchers can, therefore, use these 12 items, either alone or in combination with other information, to determine if functional ankle instability is present.

Journal Article↗

PubMedDate not supplied

Low-load eversion force sense, self-reported ankle instability, and frequency of giving way.

CONTEXT: Functional ankle instability has been attributed to proprioceptive loss. However, in previous studies of proprioception,authors have not investigated the ability to sense force at the ankle. Additionally, previous investigators have viewed functional ankle instability as either a present or absent condition,rather than a continuum. OBJECTIVE: To determine the relationship of ankle giving-way frequency and perceived ankle instability to ankle eversion force sense. DESIGN: Cohort design. SETTING: Sports medicine research laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty individuals (5 men,15 women) with a history of unilateral ankle instability. INTERVENTION(S): We tested subjects with 2 loads: 10% and 30% of maximal voluntary isometric contraction. MAIN OUTCOME MEASURE(S): We measured eversion force sense by calculating absolute, constant, and variable errors from a 3-trial force-matching procedure. Furthermore, subjects reported their frequency of giving way in units of times per day,week, or month, and these data were extrapolated to estimate annual giving-way frequency. Finally, subjects answers to 6 questions about ankle stability during typical daily or sports activities were summed to create a perceived ankle instability index. RESULTS: Significant relationships were found for only the 10% maximal voluntary isometric contraction. For absolute error,a positive relationship existed between the number of self reported episodes of giving way and eversion force sense for both ipsilateral (r .58) and contralateral (r .49) testing of the injured ankle. Constant error was correlated with giving way(r = -.56) for ipsilateral testing of the injured ankle. The ankle instability index was also positively correlated with eversion force sense absolute error (r .51) for ipsilateral testing only. CONCLUSIONS: Our results suggest that subjects with ankle instability had difficulty replicating eversion forces. Specifically,larger errors were related to both self-reported giving-way episodes and perceived ankle instability.

Journal Article↗

PubMedDate not supplied

Prophylactic ankle braces and knee varus-valgus and internal-external rotation torque.

CONTEXT: Although prophylactic ankle bracing has been shown to be effective in reducing the incidence of ankle sprains,how these ankle braces might affect the other joints of the lower extremity is not clearly understood. OBJECTIVE: To determine the effects of a prophylactic ankle brace on knee joint varus-valgus and internal-external rotation torque during a drop landing onto a slanted surface. DESIGN: A repeated-measures design. SETTING: Biomechanics research laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-four physically active college students. INTERVENTION(S): Participants were tested in a brace and no brace condition. MAIN OUTCOME MEASURE(S): We measured 3 dependent variables:(1) peak ankle inversion-eversion torque, (2) peak knee varus-valgus torque, and (3) peak knee internal-external rotation torque. A force plate was used to collect ground reaction force data, and 6 motion analysis cameras collected kinematic data during the unilateral drop landing. An adjustable bar was hung from the ceiling, and a slant board was positioned over the center of the force plate, so that the ankle of the participant's dominant leg would invert upon landing. Peak torque was measure din both the brace and no-brace conditions. The average of the peak values in 3 trials for both conditions was used for the statistical analysis. RESULTS: Ankle eversion torque was significantly greater in the brace condition (F1,23 19.75, P < .01). Knee external rotation torque was significantly greater in the brace condition(F1,23 4.33, P <.05). Valgus knee torque was smaller in the brace condition, but the difference was not statistically significant(F1,23 3.45, P .08). CONCLUSIONS: This study provides an important first step in understanding the effects of prophylactic ankle bracing on other joints of the lower extremity. We found that prophylactic ankle bracing did have an effect on knee torque when the subject was landing on a slanted surface. Specifically, knee external rotation torque increased when the ankle was braced.

Journal Article↗