Lateral ankle sprains, which are primarily caused by an

Transcription

1 Erin Caffrey, MS, ATC1 Carrie L. Docherty, PhD, ATC2 John Schrader, HSD, ATC3 Joanne Klossner, PhD, ATC 4 The Ability of 4 Single-Limb Hopping Tests to Detect Functional Performance Deficits in Individuals With Functional Ankle Instability Lateral ankle sprains, which are primarily caused by an inversion stress to the joint, account for 34% of all injuries in athletics. 13 Additionally, up to 40% of individuals report a sense of instability after an initial sprain that may lead to recurrent instability. 15 Functional ankle instability (FAI) is described as a feeling of giving way in the ankle joint, 8-11,15,19,35 which may or may not occur in the presence of laxity of the lateral ligaments. 8,19,21,27 t Study Design: Experimental laboratory testing using a cross-sectional design. t Objectives: To determine if functional performance deficits are present in individuals with functional ankle instability (FAI) in 4 single-limb hopping tests, including figure-of-8 hop, side hop, 6-meter crossover hop, and square hop. t Background: Conflicting results exist regarding the presence of functional deficits in individuals with FAI. It is important to evaluate whether functional performance deficits are present in this population, as well as if subjective feelings of giving way can assist in identifying these deficits. t Methods: Sixty college students volunteered for this study. Thirty participants with unilateral ankle instability were placed in the FAI group and 30 participants with no history of ankle injuries were placed in the control group. The FAI group was subsequently further divided to indicate those that reported giving way during the functional test (FAI-GW) and those that did not (FAI-NGW). Time to complete each test was recorded and the mean of 3 trials for each test were used for statistical analysis. To identify performance differences, we used 4 mixed-design 2-way (side-by-group) ANOVAs, 1 for each hop test. A Tukey post hoc test was completed on all significant findings. t Results: We identified a significant side-bygroup interaction for all 4 functional performance tests (P.05). Specifically, for each functional performance test, the FAI limb performed significantly worse than the contralateral uninjured limb in the FAI-GW group. Additionally, the FAI limb in the FAI- GW group performed worse than the FAI limb in the FAI-NGW group, and the matched limb in the control group in 3 of the 4 functional performance tests. t Conclusion: We found that functional performance deficits were present in participants with FAI who also experienced instability during the test. This difference was identified when comparing the FAI limb to the contralateral uninjured limb as well as control participants. However, the performance deficits identified in this study were relatively small. Future research in this area is needed to further evaluate the clinical meaningfulness of these findings. Finally, we found that limb dominance did not affect performance. J Orthop Sports Phys Ther 2009;39(11): doi: /jospt t Key words: 6-meter crossover hop, agility, figure-of-8 hop, side hop, square hop How these subjective feelings of giving way affect actual functional performance or sport participation remains an area of debate. While it seems inherent that those with FAI will have functional deficits, this has not been consistently reported in the literature. Developed with the intentions of tracking rehabilitation and determining return-to-play criteria, functional performance testing provides an unbiased means of measuring functional ability. 10 Most of the research on functional performance testing relates to the knee and, more specifically, to testing individuals with anterior cruciate ligament-deficient and reconstructed knees. 4,12,16,20,24-26,28,29,34,37 Functional performance tests range from general lower extremity tests to unilateral hopping tests. 1,2,4,6,12,16-18,20,22,24,29-33,37 Limited studies exist evaluating the presence of functional deficits in patients with FAI. 7,9,10,21,27,39 Even with the small amount of research available, the studies present with conflicting results, adding to the confusion regarding the nature of this condition. Studies that used general lower extremity tests, such as the 6-meter shuttle run 9,27 and cocontraction test, 9 found no performance deficits in participants with FAI. Of 6 studies that used unilateral 1 Athletic Trainer, Saint Gertrude High School, Bon Secours Richmond Health System, Midlothian, VA. 2 Associate Professor, Department of Kinesiology, Indiana University, Bloomington, IN. 3 Clinical Professor, Department of Kinesiology, Indiana University, Bloomington, IN. 4 Clinical Assistant Professor, Department of Kinesiology, Indiana University, Bloomington, IN. The protocol for this study was approved by the Indiana University Institutional Review Board. Address correspondence to Dr Carrie L. Docherty, Department of Kinesiology, Indiana University, 2805 E 10th St, Bloomington, IN cdochert@indiana.edu journal of orthopaedic & sports physical therapy volume 39 number 11 november

2 hopping tests, only 3 reported significant differences in performance between FAI and uninjured participants. 7,10,21 Due to the conflicting results with previous performance studies and the importance of understanding if functional deficits exist when making return-to-play decisions, continued research in this area is needed. Therefore, the purpose of this study was to determine if functional performance deficits are present in individuals with FAI in 4 single-limb hopping tests, including figure-of-8 hop, side hop, 6-meter crossover hop, and square hop tests, when compared to their contralateral uninjured ankle and healthy control participants. METHODS Subjects We recruited 60 physically active participants from a large university. Participants were separated into 2 groups: 30 with FAI (15 males, 15 females; mean SD age, years; height, cm; body mass, kg) and 30 control subjects (15 males, 15 females; mean SD age, years; height, cm; body mass, kg). In the FAI group, all participants had unilateral ankle instability, as determined with the Ankle Instability Instrument (APPENDIX). 11 All participants with FAI needed to answer yes to questions 1 and 4 on the Ankle Instability Instrument, which asked if an ankle had ever been sprained before and if a feeling of giving way was ever present. 11 Participants also needed to answer yes to at least 1 of questions 5 through 9 regarding if instability was felt while walking on a flat surface, walking on an uneven surface, during recreational or sport activity, going up stairs, or coming down stairs. 11 For the 30 subjects with FAI, 21 (70%) reported seeing a physician after their initial ankle sprain. Of these, 4 were diagnosed with a mild ankle sprain and 17 were diagnosed with a moderate ankle sprain. Additionally, 13 required the use of crutches after their initial ankle sprain. We excluded potential participants with FAI if they had a history FIGURE 1. Functional performance tests. of injury to the involved lower limb besides the ankle, had acute symptoms of an ankle sprain (including swelling and redness), history of injury in the contralateral limb, or were currently undergoing a formal rehabilitation program. Participants included in the control group had no previous history of ankle injury to either limb, as well as answered no to all questions on the Ankle Instability Instrument. We also excluded participants from either group if they had a history of a lower limb fracture, surgery, or low back injury. All participants engaged in physical activity, including activities such as jogging, biking, or swimming at least 3 times a week for an hour each session. Indiana University s Institutional Review Board approved the study, and all participants read and signed a written informed consent prior to testing. Procedures Each participant performed a 5-minute warm-up on a stationary bike at a moderate intensity, as defined by an 11 or 12 on the Borg Rate of Perceived Exertion Scale (scores range from 6 [ very, very light ] to 20 [ very, very hard ]). 36 Participants then completed 4 functional performance tests, the figure-of-8 hop, side hop, 6-meter crossover hop, and square hop. We timed each test with an electronic timer (Speedtrap 2, Brower Timing Systems, Draper, UT). Prior to testing, a standardized video recording, along with verbal instructions demonstrated how to perform each functional test for each participant. After warming up, we recorded the dominant limb for each participant as the limb chosen to kick a ball. Limb dominance and gender were subsequently used as the criteria to match limbs between the FAI and control groups. All participants performed up to 3 practice trials of each performance test to familiarize themselves with the testing procedures, followed by 3 trials at maximal effort. The participants rested for at least 1 minute between each individual trial. We counterbalanced the order of functional performance test and limb for all participants. For the figure-of-8 hop test, a 5-m course outlined by cones was used (FIG- URE 1). Each participant was instructed to hop on 1 limb, twice around the course, as fast as possible. We marked any trials in which a participant put the contralateral foot down, fell, missed the stopwatch pad, or did not complete the course as outlined as unacceptable and asked to perform the trial again. 10,20 Prior to data collection, trial reliability was conducted for each test. Using 3 trials, reliability for this test was excellent, with an intraclass correlation coefficient (ICC 2,1 ) of 0.95 (SEM, 1.66 seconds; MDC 95 [minimal detectable change], 4.59 seconds). For the side hop test, all participants were instructed to hop on 1 limb laterally over a 30-cm distance (FIGURE 1). One repetition constituted hopping laterally 30 cm and back to the starting location. Each participant completed 10 repetitions and was instructed to do so 800 november 2009 volume 39 number 11 journal of orthopaedic & sports physical therapy

3 Square Hop (s) Figure-of-Eight Hop (s) Side Hop (s) 6-Meter Crossover Hop (s) * * * * FAI/GW FAI/NGW Control FAI/matched limb Uninjured FIGURE 2. Mean time values for the involved and uninvolved limbs of the 3 groups. *Denotes a significant difference between the subjects with FAI (functional ankle instability) and uninjured limb in the FAI-GW (subjects with FAI who reported giving way during functional test) group. Denotes a significant difference between the FAI limb in the FAI-GW group and the FAI limb in the FAI-NGW (subjects with FAI who did not report giving way during functional test) group, and the matched limb in the control group. as quickly as possible. If a participant fell, put the contralateral foot down, missed the stopwatch pad, or did not completely clear the 30-cm distance while hopping the trial, we recorded the trial as unacceptable and the participant repeated the trial again. 10,20 Again, trial reliability was conducted for this test and determined to be good with an ICC 2,1 of 0.84 (SEM, 2.10 seconds; MDC 95, 5.82 seconds). In the 6-meter crossover hop test, a line 6 m long was used. The participants were instructed to hop on 1 limb diagonally over the 15-cm-wide line, alternating sides for the entire 6 m, as fast as possible (FIGURE 1). We recorded a trial as unacceptable if the participant put the contralateral foot down, fell, missed the stopwatch pad, or did not completely clear the width of the line. The trial was repeated if not acceptable. Trial reliability for this test was excellent, with an ICC 2,1 of 0.96 (SEM, 0.37 seconds; MDC 95, 1.03 seconds). The square hop consists of a cm square marked on the floor with tape (FIGURE 1). Starting outside of the square, participants were instructed to hop in and out of the square as fast as possible for 5 repetitions. One repetition constituted hopping in and out of the tape outline completely around the square back to the starting point. With the right limb, participants hopped in a clockwise direction and, with the left limb, they hopped in a counterclockwise direction. When a participant fell, put the contralateral foot down, hopped in the wrong direction, missed the stopwatch pad, did not completely clear the outline of the tape on the right and left sides of the square, or did not clear the outline of the tape on the top and bottom of the square with the balls of the feet, we marked the trial as unacceptable and the participant repeated the trial. Trial reliability for this test was good, with an ICC 2,1 of 0.90 (SEM, 1.40 seconds; MDC 95, 3.88 seconds). For all participants, we recorded the time to complete each test and used the mean of the 3 trials for each test for statistical analysis (FIGURE 2). After each functional performance test, subjects journal of orthopaedic & sports physical therapy volume 39 number 11 november

4 TABLE were asked if they felt unstable or had a feeling of giving way during that trial. The answer was recorded for each trial. To identify performance differences, we used 4 mixed-design 2-way (side-bygroup) ANOVAs, 1 for each test, with side (FAI limb versus uninjured limb) as the repeated factor and group (FAI versus control) as the independent factor. Tukey post hoc analysis was conducted on any significant findings. The alpha level for all analyses was P.05. RESULTS We found a significant side-bygroup interaction in the figureof-8 hop (F 1,58 = 6.23, P =.02) and side hop (F 1,58 = 6.10, P =.02). Specifically, these differences were identified between the limbs (injured versus uninjured) in the FAI group. Based upon our inclusion criteria, subjects performed worse on the FAI limb than the uninjured limb on the figure-of-8 hop (mean difference, 0.24 seconds; 95% confidence interval [CI]: 0.01 to 0.50 seconds; P =.06) and the side hop (mean difference, 0.37 seconds; 95% CI: 0.01 to 0.73 seconds; P =.05). No differences were observed for the 6-meter cross- Mean and Standard Error for Each Functional Performance Test* Subjects With FAI FAI Limb uninjured Limb FAI with giving way during FPTs Figure-of-8 hop Side hop meter crossover hop Square hop FAI with no giving way during FPTs Figure-of-8 hop Side hop meter crossover hop Square hop Control Subjects Matched Involved Limb Matched Uninjured Limb Figure-of-8 hop Side hop meter crossover hop Square hop Abbreviations: FAI, functional ankle instability; FPTs, functional performance tests. * Data are mean standard error seconds. over hop and the square hop between the limbs or between the groups (P.05). Additionally, we did not identify a significant difference between the limbs of the control group for any of the 4 tests (P.05). After the initial analysis, we determined that subjects in the FAI group could be further divided, depending on individual reports of instability or giving way during the actual performance of the test. Thirteen (43%) of the subjects in the FAI group reported a sensation of giving way during performance of the figureof-8 test, 14 (47%) while performing the side hop, 8 (27%) while performing the crossover hop, and 11 (37%) during the square hop. This distribution allowed us to re-analyze the data using 3 groups (FAI subjects who reported giving way during functional test [FAI-GW], FAI subjects who did not report giving way during functional test [FAI-NGW], and control subjects). For this analysis we again used 4 mixed-design 2-way (side-by-group) ANOVA, one for each test, with side (FAI limb versus uninjured limb) as the repeated factor and group (FAI-GW, FAI-NGW, control) as the independent factor. The secondary analysis yielded a significant side-by-group interaction for all 4 functional performance tests (figureof-8 hop [F 1,57 = 3.46, P =.04], side hop [F 1,57 = 3.83, P =.03], 6-meter crossover hop [F 1,57 = 6.22, P =.01], and square hop [F 1,57 = 3.25, P =.05]). Results of the Tukey post hoc tests are reported individually for each functional performance test. Means and standard errors for all tests are located in the TABLE. Figure-of-8 For the figure-of-8 test, there was a significant difference between the FAI and uninjured sides for the FAI-GW group (mean difference, 0.37 seconds; 95% CI: 0.01 to 0.75 seconds; P =.05). However, we did not identify any performance differences between the 3 groups or between the sides of the control group (P.05) (FIGURE 2). Side Hop For the side hop, the subjects in the FAI- GW group performed worse on the FAI limb than subjects in the FAI-NGW group (mean difference, 2.00 seconds; 95% CI: 0.70 to 3.31 seconds; P =.01) and the control group (mean difference, 1.61 seconds; 95% CI: 0.51 to 2.72 seconds; P =.01). We also found that subjects in the FAI-GW group performed worse on their FAI limb than their uninjured limb (mean difference, 0.57 seconds; 95% CI: 0.08 to 1.06 seconds; P =.02). No difference between the limbs was identified in either the FAI-NGW or control groups (P.05) (FIGURE 2). 6-Meter Crossover Hop We found that with the 6-meter crossover hop subjects in the FAI-GW group performed worse on the FAI limb than subjects in the FAI-NGW group (mean difference, 0.96 seconds; 95% CI: 0.32 to 1.60 seconds; P =.01) and the control group (mean difference, 0.93 seconds; 95% CI: 0.31 to 1.55 seconds; P =.01). Also, subjects in the FAI-GW group performed worse on their FAI limb than their uninjured limb (mean difference, 0.42 seconds; 95% CI: 0.16 to 0.68 seconds; P =.01). No difference between the limbs was identified in either the FAI-NGW or control groups (FIGURE 2). 802 november 2009 volume 39 number 11 journal of orthopaedic & sports physical therapy

5 Square Hop For the square hop, we found that subjects in the FAI-GW group performed worse on the FAI limb than subjects in the FAI-NGW group (mean difference, 3.78 seconds; 95% CI: 0.76 to 6.80 seconds; P =.02) and the control group (mean difference, 3.28 seconds; 95% CI: 0.51 to 6.04 seconds; P =.02). Subjects in the FAI-GW group also performed worse on their FAI limb than their uninjured limb (mean difference, 2.22 seconds; 95% CI: 0.34 to 4.09 seconds; P =.02). No difference between the limbs was identified in either the FAI-NGW or control groups (FIGURE 2). DISCUSSION The purpose of this study was to evaluate the presence of functional performance deficits in individuals with FAI on 4 single-limb hopping tests. To date, previous research has provided conflicting results when determining if performance deficits exist in individuals with FAI. Only a small number of studies have actually reported differences in performance between individuals with FAI and healthy participants, 7,21 or even between limbs in participants with unilateral FAI. 10,21 This study provides a unique contribution to the literature, based on how we classified the groups. For the initial statistical analysis, a significant difference was identified for 2 of the 4 functional tests; however, the differences between the FAI and control groups were relatively small. By further separating the FAI group into those that experienced giving-way during the actual functional test and those that did not, we combined both the subjective perception of FAI and the objective performance measures. Interestingly, we found that the group that reported feelings of instability during the functional task also yielded the largest side-to-side performance differences. Subsequently, the participants that were identified as FAI by the questionnaire but did not report instability during the functional tests had very small, nonsignificant, side-to-side performance differences. Because the majority of other studies did not consider further dividing the subjects in this manner, this might be a reason for the inconsistencies in the literature. Type of Functional Performance Tests We chose these 4 functional tests based on their ability to stress the lateral aspect of the ankle joint and to recreate the mechanisms that may lead to the perception of functional instability. 10 Because we timed all 4 tests over a set distance or course, we classified the tests as agility movements. 14 Agility maneuvers consist of sudden changes in direction that occur in response to a stimulus, which are a required element in many competitive sports, and encompass many physical components, like coordination and speed. 14 In general, tests requiring agility may better represent functional movements necessary for athletic participation, and thus may be more difficult to perform. Specifically with FAI, these tests may include the motions during sport activity that bring about feelings of instability. Previous FAI studies using single-limb functional tests were based on either agility movements, such as the single-limb hopping course, 7,21 or muscular power movements like the single-limb hop for distance. 10,39 Muscular power movements are those requiring maximal muscle strength to produce a force at a high speed over a given period. 23 Of the previously reported FAI studies, none of the muscular power performance tests and only a few agility tests identified performance deficits in individuals with FAI. 9,10,21,27,38,39 Of the agility tests that did not produce performance differences, the tests were either completed primarily in the frontal plane, requiring little rotational or lateral movements, or were not timed. 9,10,39 All of the tests in our study forced participants to perform them not only as quickly as possible but also while moving in the sagittal plane or multiple directions. Combining these aspects of functional performance allowed us to detect deficits in the subjects with FAI. Therefore, development of functional per- formance tests for FAI should emphasize timed agility movements that focus on faster, complex sagittal plane or rotational motions rather than muscular power. Classification of Patients With FAI Like many orthopedic injuries, FAI may also include a range of severities. This is evident in the current investigation. When simply using the questionnaire to identify those with FAI, we found a wide range of performance values. When subjects were asked to perform a functional task and report instability during that task, a separate cohort emerged. This led us to conclude that patients who report instability during actual functional performance may have more severe FAI. In fact, those identified as having FAI by the traditional classification (initial ankle sprain and repeated episodes of giving way), but did not have giving way during the functional task, actually performed very similarly to the control subjects. Therefore, adding this functional component to the inclusion criteria should be considered in future FAI investigations. These findings also reiterate that (1) accurate classification of FAI is critical, (2) patients with FAI have a range of severity, and (3) criteria that combine both subjective and objective measures might be the best method to classify those with FAI. Performance Differences Between FAI and Control Groups An objective of this study was to determine if subjects with FAI performed worse on the single-limb hopping tests when compared to those in the control group. Our findings support the hypothesis that performance deficits are present in those with more severe FAI. We identified statistically significant performance differences between the FAI-GW and control groups in 3 of the 4 hopping tests. While these findings agree with other previously published studies, 7,21 it is important to acknowledge that the performance deficits identified in the FAI-GW were relatively small. In some situations the performance deficit was smaller than the SEM values identified during reliability journal of orthopaedic & sports physical therapy volume 39 number 11 november

6 testing. Therefore, when evaluating patients in a clinical setting, it may be difficult to identify deficits in performance based on these functional tests, because variation in performance on repeated testing are likely greater than any difference in performance due to FAI. Future research is needed to determine the range of performance times that should be present in a normal population and what values may be indicative of a patient with ankle pathology. Other FAI functional performance research comparing groups reported an array of conflicting results. In a previous study, performance deficits in participants with FAI were identified in 2 of 4 functional tests. Interestingly, they identified deficits when performing figure-of-8 hop and side hop tests, yet no deficits were identified with the up-down hop and single-limb hop for distance. 10 This difference was probably due to the varying amount of stress placed on the ankle during each of these tests. Buchanan et al 7 found performance differences between a control and FAI group on a single-limb hopping test, but not during performance of the single-limb hurdle test. 7 The authors concluded that the hurdle test was too difficult to perform because they believed that the height of the hurdles was too high. 7 Finally, Demeritt et al 9 also compared FAI and control groups but failed to find performance deficits between the groups. Two of the functional performance tests were double-limb tests the cocontraction test and shuttle run. Their intended function was to stress the hamstrings and quadriceps muscle groups more so than the ankle joint, which could explain why no differences were found. The third test was a single-limb agility hop, but the test was not timed and required participants to balance for 5 seconds before proceeding to hop in the next direction. Even though the test consisted of lateral and diagonal movements, only the numbers of errors seen with balancing were measured. 9 Performance Differences Between the Limbs In addition to measuring performance Clinical Implications Clinically, these tests can be used in conjunction with subjective questiondifferences between the groups, we also evaluated the differences in performance of the FAI limb and uninjured limb of the FAI groups, as well as the sides of the control group. By evaluating both limbs, we attempted to establish the ability of using the uninjured limb as a control when conducting functional performance tests. First, by comparing the limbs in the control group, we evaluated the role of limb dominance on functional performance. We found no differences between sides in the control group, thus confirming that limb dominance does not play a role in performance of these functional tests. Jerosch and Bischof 21 found similar results with the control subjects on the agility hopping course. Other research using the single-limb hop for distance, 30-meter agility hop, and 6-meter timed hop also confirms that limb dominance does not affect performance. 3-6,17,22,24,30,31 Clinically, this finding may eliminate the need for pretest scores as a baseline, because the uninjured limb may be used for comparison. Next we evaluated the difference between the functionally unstable ankle and the uninjured ankle in the FAI groups. When conducting the secondary analysis, we found a significant difference between sides for the FAI-GW group; however, no side-to-side difference was found in the FAI-NGW group. When reviewing each test individually, during the figure-of-8 hop the FAI-GW group had a side-toside difference of 0.37 seconds, while it was only 0.13 seconds for the FAI-NGW group. With the side hop, a side-to-side difference of 0.57 seconds was seen in the FAI-GW group, whereas the difference in the FAI-NGW group was only 0.13 seconds. Performance in the 6-meter crossover hop yielded a side-to-side difference of 0.42 seconds in the FAI-GW group, compared to 0.01 seconds in the FAI- NGW group. Finally, during the square hop, the FAI-GW group had a side-toside difference of 2.22 seconds, while the FAI-NGW group had a difference of only 0.06 seconds. This again reiterates the major difference between these 2 cohorts of people with FAI. Jerosch and Bischof 21 also reported differences between the injured and uninjured sides of FAI participants when performing a single-limb hopping course; however, other FAI performance studies comparing limbs were unable to reproduce this finding. 27,39 This may be due to the nature of the performance tests evaluated. For example, tests that did not yield side-to-side differences included the triple-crossover hop for distance, 6-meter timed hop, single-limb hop for distance, and 30-meter agility hop. 27,39 Both the triple-crossover hop for distance and single-limb hop for distance primarily measure muscle power, and the 30-meter agility hop and the 6-meter timed hop do not require sharp lateral changes in direction. As previously described, the characteristics of these tests may have hindered their abilities to elicit significant differences. Future Research We recommend that future research investigate different tests modified or created specifically with the lateral and rotational aspects of movement at the ankle in mind. Once consistent results are obtained, sensitivity, specificity, and accuracy should also be evaluated in these functional performance tests. As we continue to develop tests that identify performance deficits in individuals with FAI, research should begin to move towards establishing a battery of screening tests that will help to prescreen individuals for early intervention. Research on functional performance tests developed for FAI should also be performed on control participants. The purpose of testing healthy individuals would be to establish a normal lower limb symmetry index for each functional performance test. This would help to determine lower limb symmetry ranges that could be used for reference when clinically evaluating a patient with FAI. 804 november 2009 volume 39 number 11 journal of orthopaedic & sports physical therapy

7 naires to better classify the severity of disability in patients with FAI. This could assist clinicians in initiating rehabilitation protocols to reduce the risk of future episodes of instability or giving way during athletic participation. These functional performance tests could also be used to track progress during the rehabilitation process. CONCLUSION We found that individuals who were classified as FAI by a subjective questionnaire and who also reported instability during actual functional performance had significantly slower times in 3 of the 4 tests when compared to the healthy participants. Deficits for the limb with FAI compared to the contralateral uninjured limb were also identified in the FAI-GW group in all tests. Results from this investigation support prior studies establishing that performance deficits do exist in individuals with FAI when using single-limb functional tests. 10,21 Also, we further demonstrated that limb dominance does not affect performance. 4,6,17,21,22,24,30,31 t KEY POINTS Findings: We found functional performance deficits in participants with FAI who perceived instability during the test, when comparing the ankle with functional instability to the contralateral uninjured limb as well as to control participants. Implication: Interpretation of these results indicates that functional performance deficits exist in individuals with severe FAI and may be identified with functional tests that place stress on the lateral ankle structures. Caution: These results lead us to believe that, while people with FAI may have functional performance deficits, these may range substantially, depending on the severity of FAI. 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8 Scand J Med Sci Sports. 1998;8: Paterno MV, Greenberger HB. The test-retest reliability of a one legged hop for distance in young adults with and without ACL reconstruction. Isokinet Exer Sci. 1996;6: Perry MC, Morrissey MC, Jones JS, et al. Number of repetitions to maximum in hop tests in patients with anterior cruciate ligament injury. Int J Sports Med. 2005;26: dx.doi.org/ /s Petschnig R, Baron R, Albrecht M. The relationship between isokinetic quadriceps strength test and hop tests for distance and one-legged vertical jump test following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 1998;28: Risberg MA, Ekeland A. Assessment of functional tests after anterior cruciate ligament surgery. J Orthop Sports Phys Ther. 1994;19: Rozzi SL, Lephart SM, Sterner R, Kuligowski L. Balance training for persons with functionally unstable ankles. J Orthop Sports Phys Ther. 1999;29: Tabor M, Davies G, Kernozek T, Negrete R, Hudson V. A multicenter study of the test-retest reliability of the Lower Extremity Functional Test. J Sport Rehab. 2002;11: Wilk KE, Romaniello WT, Soscia SM, Arrigo CA, Andrews JR. The relationship between subjective knee scores, isokinetic testing, and functional testing in the ACL-reconstructed knee. J Orthop Sports Phys Ther. 1994;20: Wilson A. The effects of functional ankle instability on performance of the single-limb hurdle and single-limb hopping course in a braced and non-braced condition [thesis]. Bloomington, IN: Indiana University; Worrell TW, Booher LD, Hench KM. Closed kinetic chain assessment following inversion ankle sprain. J Sport Rehabil. more information Instructions appendix ANKLE INSTABILITY INSTRUMENT This form will be used to categorize your ankle instability. A separate form should be used for the right and left ankles. Please fill out the form completely. If you have any questions, please ask the administrator of the survey. Thank you for your participation. 1. Have you ever sprained an ankle? Yes No 2. Have you ever seen a doctor for an ankle sprain? Yes No If yes, 2a. How did the doctor categorize your most serious ankle sprain? Mild (grade 1) Moderate (grade 2) Severe (grade 3) 3. Did you ever use a device (such as crutches) because you could not bear weight due to an ankle sprain? Yes No If yes, 3a. In the most serious case, how long did you need to use the device? 1-3 days 4-7 days 1-2 weeks 2-3 weeks 3 weeks 4. Have you ever experienced a sensation of your ankle "giving way"? Yes No If yes, 4a. When was the last time your ankle "gave way"? 1 month 1-6 months ago 6-12 months ago 1-2 years ago 2 years ago 5. Does your ankle ever feel unstable while walking on a flat surface? Yes No 6. Does your ankle ever feel unstable while walking on uneven ground? Yes No 7. Does your ankle ever feel unstable during recreational or sport activity? Yes No N/A 8. Does your ankle ever feel unstable while going up stairs? Yes No 9. Does your ankle ever feel unstable while going down stairs? Yes No Reprinted with permission from the Journal of Athletic Training. "Docherty, Gansneder, Arnold, Hurwitz: Development and Reliability of the Ankle Instability Instrument. 2006; 41(2): november 2009 volume 39 number 11 journal of orthopaedic & sports physical therapy