Performance on the modified star excursion balance test at the time of return to sport following anterior cruciate ligament reconstruction.

Performance on the modified Star Excursion Balance Test at the time of Return to Sport following Anterior Cruciate Ligament Reconstruction Sarah Clagg, PT, DPT, SCS, AT1 Mark V. Paterno, PT, PhD, SCS, AT2 Timothy E. Hewett, PhD, FACSM3 Laura C. Schmitt, PT, PhD4

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1Physical

Therapist, Sports Certified Specialist, Athletic Trainer, OSU Sports Medicine, The Ohio State University Wexner Medical Center, Columbus, OH. 2Associate Professor, Sports Medicine Biodynamics Center, Division of Occupational Therapy and Physical Therapy, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 3Professor and Director of Research, Sports Health & Performance Institute, The Ohio State University, Columbus, OH; Professor, Departments of Physiology and Cell Biology, Orthopaedic Surgery, Family Medicine, Biomedical Engineering and School of Health and Rehabilitation Sciences, College of Medicine, Ohio State University, Columbus, OH; Professor, Sports Medicine Biodynamics Center and Human Performance Laboratory, Cincinnati Children's Hospital Medical Center, Cincinnati, OH; Professor, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH. 4Assistant Professor, Division of Physical Therapy, School of Health and Rehabilitation Sciences, Ohio State University, Columbus, OH; Adjunct Faculty, Sports Medicine Biodynamics Center, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH.

The Cincinnati Children’s Hospital Medical Center Institutional Review Board approved the protocol for this study. Funding: This work was funded by support from the National Institutes of Health grant F32AR055844 and the National Football League Charities Medical Research Grants 2007, 2008, 2009, 2011.

The authors certify that they have no affiliations with or financial involvement in any organization or entity with a direct financial interest in the subject matter or materials discussed in the article. Address correspondence to Dr. Laura C. Schmitt, 453 W 10th Avenue, 516 Atwell Hall, Columbus, OH 43210. E-mail: [email protected] 1


Study Design: Cross-sectional.

1 2 3

Objectives: To compare performance on the modified star excursion balance test (SEBT)

4

between participants with anterior cruciate ligament reconstruction (ACLR) at the time of return

5

to sport and uninjured control participants.

6

Background: The modified SEBT is a clinical tool to assess neuromuscular control deficits.

7

Deficits in dynamic stability and neuromuscular control persist after ACLR, but assessment with

8

the modified SEBT in this population at the time of return to sport has not been reported.

9

Methods: Sixty-six participants (mean age: 17.6 years) at the time of return to sport following

10

unilateral primary ACLR (ACLR group) and 47 uninjured participants (mean age: 17.0 years)

11

serving as a control group (Control group) participated. For the modified SEBT, the anterior,

12

posteromedial, and posterolateral reach distances were recorded. Lower extremity muscle

13

strength was quantified with isokinetic dynamometry. Independent samples t-tests were used to

14

evaluate performance differences between the ACLR and Control groups and between ACLR

15

sub-groups. In the ACLR group, bi-variate correlations determined the association of modified

16

SEBT performance with time since surgery and lower extremity muscle strength.

17

Results: The ACLR group had lower anterior reach distance on the involved and uninvolved

18

limbs compared to the Control group. There were no differences observed between groups in

19

reach distances for the posteromedial and posterolateral directions or limb symmetry indices for

20

any of the reach directions. In the ACLR group, time from surgery and meniscal status at the

21

time of ACLR did not influence modified SEBT performance while participants with patellar

22

bone-tendon-bone grafts had lower posterolateral reach distance compared to those with

23

hamstring grafts. In the ACLR group, involved limb hip abduction strength positively correlated

24

with all reach distances and quadriceps strength positively correlated with posterolateral reach.

25

Conclusion: At the time of return to sport, participants post-ACLR demonstrated reduced

26

modified SEBT anterior reach in both involved and uninvolved limbs compared to uninjured

2


27

participants, with no other group differences. In the ACLR group, modified SEBT reach distance

28

was associated with lower extremity muscle strength, but not with time from reconstruction or

29

meniscal status at the time of ACLR. Lower extremity muscle strength and graft type may

30

interact to influence modified SEBT posterior reach performance but this requires further study.

31

Level of Evidence: Prognosis, level 2b–.

32

Key Words: ACL, ACL reconstruction, dynamic stability, knee, performance

3

Knee ligament injury is common in athletics, and affects both male and female athletes who compete in cutting and pivoting sports. A recent study in the United States followed high school athletes for 5 years and reported an injury rate that required surgery of 1.45 athlete per 10 000 athlete exposures.43 Of the 1380 injuries that required surgery, 49.4% were knee


injuries, with the most common injury being complete ligament tears.43 Anterior cruciate ligament (ACL) rupture is one of the most common and devastating injuries in high-school age individuals and young adults.26, 33 A majority of young individuals with ACL injury undergo reconstruction to return to higher level activities, with significant costs to society.33 Beyond the societal impact, ACL injury and reconstruction results in significant personal burden in the shortterm, including functional deficits and increased risk of second ACL injury, and in the long-term with increased likelihood of joint morbidity.16, 26, 32, 40, 55 Several studies show significant and persistent deficits in activity participation and function following ACL reconstruction (ACLR). A recent systematic review shows moderate rates of return to sport following ACLR, with only 44% of athletes returning to competitive play.3 Residual impairments are cited as a common limiting factor in return to pre-injury level of activity.3 At the time of return to sport, recent work in young individuals with ACLR showed significant deficits in quadriceps strength in approximately 44% of the sample.46 Further, those with deficits in quadriceps femoris muscle strength demonstrated decreased function and performed worse on single leg hop tests compared to those without strength deficits and uninjured individuals.46 Other studies show that these deficits in strength and quadriceps activation may persist for up to 2 years following ACLR.44 Persistent deficits in dynamic stability, specifically measures of proprioception and neuromuscular control, are also observed following ACLR.9 Recent prospective work identified deficits in postural stability, a component of dynamic stability, as a predictor of second ACL injury in young individuals with ACLR after return to sport.40 Dynamic postural control or stability is typically measured in the laboratory using force platforms or other sophisticated equipment. 4

However, clinical tools to evaluate dynamic postural control, defined as maintenance of a stable base of support while performing prescribed tasks, have also been developed. The modified star excursion balance test (SEBT) is a functional screening tool to assess lower extremity dynamic stability and neuromuscular control,9, 27, 35, 53 encompassing lower extremity strength,


coordination, balance, and flexibility.2,8, 15 Following lower extremity injury, the modified SEBT is used to measure the extent of remaining deficits and to evaluate recovery. The modified SEBT has been found to be a reliable assessment tool with high test-retest reliability20, 23, 45 and has been shown to discriminate dynamic balance and neuromuscular control strategies between limbs following unilateral lower extremity injury.18, 53 Despite the clinical utility of the modified SEBT, only 1 published study has reported performance on the modified SEBT following ACLR.7 At an average of 2.9 years following ACLR, females post-ACLR demonstrated lower posterior reach distances with altered hip and knee kinematic strategies compared to uninjured females.7 Further evaluation of the modified SEBT in this population may offer insights to guide rehabilitation progression and return to sport decision-making. The purpose of this study was to compare the performance on the modified SEBT test (Y balance test) between participants with ACLR at the time of return to sport (ACLR group) and uninjured participants (Control group) and evaluate the influence of concomitant injury, surgery, and strength factors on modified SEBT performance after ACLR. We hypothesized that the ACLR group would show reduced performance and greater limb asymmetry on the modified SEBT compared to the Control group. In the ACLR group, we hypothesized that performance on the modified SEBT would not differ by graft type or meniscal status at the time of ACLR. Further, we hypothesized that performance on the modified SEBT in the ACLR group would not be associated with time since surgery, but would be positively associated with lower extremity muscle strength.

5

METHODS Participants A total of 113 participants, ages 13-27 years, were recruited from the community to participate in this study (TABLE 1). Sixty-six participants were recruited from orthopaedic


practices and physical therapy clinics following primary unilateral ACLR (ACLR group) (TABLE 2). Forty- seven uninjured participants were recruited from the community to serve as the control group (Control group). Participants in the ACLR group were enrolled in the study at the time of return to sport and were included if they had completed their rehabilitation program, were cleared to return to all high-level athletic activities by their surgeon and treating rehabilitation specialist, and planned to return to cutting and pivoting sports on a regular basis (≥ 50 hours/year). Neither the rehabilitation program nor the decision for return to sports was monitored by the study, as we were interested in the spectrum of patient presentation at the time of discharge using the practice standards of the treating clinician. Enrolled participants were cleared for sports participation at the discretion of their surgeon and treating physical therapist, but were not necessarily cleared by means of performance on any functional testing protocol. Participants with all graft types and with and without concomitant meniscus involvement (either repaired or debrided) were included. Exclusion criteria were a history of low back pain, lower extremity injury requiring the care of a physician in the past year, lower extremity surgery (beyond ACL injury), concomitant ligament injury beyond grade 1 medial collateral ligament injury, or skeletal immaturity requiring modification of the ACLR procedure due to open epiphyseal plates in the femur or tibia. Participants were included in the Control group if they reported no history of low back pain, lower extremity injury requiring the care of a physician in the past year, or surgery and participated regularly in pivoting and cutting sports (>50 hours/year). This study was approved by the Cincinnati Children’s Hospital Medical Center institutional internal review board and written consent was obtained prior to testing from all 6

participants and their parent/guardian, if applicable. The sample included in this study is a subset of an ongoing study of outcomes following ACLR at our institution. Procedures Initial testing included the collection of demographic and anthropometric information,


including leg length (LL) which was measured from the most distal aspect of the anterior superior iliac spine to the most distal aspect of the medial malleolus for each limb.11 For the ACLR group, the involved limb was identified as the injured limb. For the Control group, the preferred limb was designated as the first limb to contact the ground (identified via force plate data) during a bilateral landing from an elevated surface and the second limb to contact the ground was designated as the non-preferred limb.39 Each participant completed a modified SEBT (Y balance test), completing reaches in 3 directions, while wearing athletic shoes.19, 42 For the test, each participant received visual demonstration and verbal instructions by the examiner. The participants were instructed to stand in single limb stance on the test limb with the most distal aspect of their great toe at the center of a modified SEBT grid (FIGURE 1). Participants were instructed to perform maximal reaches with the non-stance limb in the anterior (ANT), posteromedial (PM), and posterolateral (PL) directions, while maintaining single leg stance on the test limb (FIGURE 1). Six practice trials were performed in each reach direction prior to formal testing.19, 42 On the seventh trial, the examiner recorded the distance (centimeters) of the most distal portion of the reach foot as it contacted the grid in each of the 3 reach directions. Hertel et al19 found a significant learning effect with the modified SEBT where the longest reach distance occurred after 6 trials followed by a plateau; therefore, the same protocol was used in this study, which was also used by Plisky and colleagues.42 Trials were discarded and repeated if the individual was unable to maintain single limb stance throughout the test, the hands came off of the hips during the test, the heel of the stance foot did not maintain contact with the floor throughout the test, weight was shifted onto the reach foot in any of the 3 reach distances, or the reaching limb did not return to the 7

start position prior to reaching in another direction. This same testing process was repeated on the opposite limb. The order of limb testing was randomized for each participant prior to testing. For each participant, thigh and hip muscle strength was quantified as torque output from an isokinetic dynamometer (Biodex Medical Systems, Shirley, NY). For quadriceps and


hamstring strength, participants were seated with their trunk fully supported, hips flexed to approximately 90°, the knee joint aligned with the dynamometer axis, and the dynamometer resistance arm secured to the distal shank. Straps secured the trunk, thigh, and pelvis to the apparatus to minimize compensatory body movement. Following up to three warm-up trials, the test protocol consisted of performing 5 maximum effort trial repetitions at 180°/s through the full available knee range of motion. Real-time verbal and visual feedback was provided throughout testing to promote maximum effort. The peak torque output (normalized to body weight) during the extension phase was recorded as quadriceps strength and peak force output during the flexion phase recorded as hamstrings strength. Hip abduction strength was assessed from a standing position in which the participants stood on the non-test limb facing the dynamometer head, as previously described.5 A strap that wrapped around the waist above the iliac crests secured the participant to a stationary platform on the non-test side. On the test limb, the dynamometer head was aligned in parallel with the coronal plane of the body with the axis of rotation aligned with the center of rotation of the hip. A custom-made attachment extending from the dynamometer arm was placed superior to the knee and secured around the thigh with a strap. Participants were instructed to grasp the top of the dynamometer head for support and to minimize movement of the torso. Following approximately 5 practice trials, 5 trial repetitions at 120°/s were performed with verbal encouragement for maximal effort. The peak torque output (normalized to body weight) during the abduction phase of the test limb was recorded. Data Management Three different measures were calculated to quantify performance on the modified SEBT: normalized reach distances, a composite score, and limb symmetry indices. For each 8

limb, the reach distance in each direction was normalized by LL and expressed as %LL.55 For each limb, the modified SEBT composite reach distance was calculated as the sum of the ANT, PM, and PL reach distances divided by 3 times LL and multiplied by 100 ([(ANT+PM+PL)/(LL*3)]x100).42 A limb symmetry index for each reach direction and the


composite score was calculated to evaluate symmetry of limb performance. For the ACLR group, limb symmetry indices were calculated by dividing the performance of the involved limb by the performance of the uninvolved limb and multiplying by 100, with 100% indicating perfect performance symmetry between the involved and uninvolved limbs. For the Control group, limb symmetry indices were calculated by dividing performance of the non-preferred limb by the preferred limb and multiplying by 100. Statistical Analysis Statistical analysis was conducted in PASW Statistics GradPack 21.0 (SPSS Inc, Chicago, IL). Independent samples t-tests and Chi square test for frequency distribution were used to assess for differences between the ACLR and Control groups in demographics, anthropometric data, and modified SEBT reach distances and limb symmetry indices. For these analyses, statistical significance was established a priori ( ≤ .05). In the ACLR group, independent samples t-tests were used to examine differences between sub-cohorts. Modified SEBT performance was compared between participants with patellar bone-tendon-bone autografts (n=26) and hamstring autografts (n=32); due to low number of participants with allograft (n=8), they were not included in the comparison. Modified SEBT performance was also compared between participants with concomitant meniscus injury at the time of ACLR (n=32) and without (n=34). For these analyses, statistical significance was established a priori ( ≤ .025) to account for multiple comparisons.

9

In the ACLR group, separate bi-variate correlations examined the association between modified SEBT performance and time from surgery to testing, as well as quadriceps, hamstrings, hip abduction strength. Statistical significance was established a priori ( ≤ .05). RESULTS


Between the ACLR and Control groups, there were no differences observed in age (P=.21), height (P=.42), LLs (P>.20), and frequency distribution of males and females (P=.85; TABLE 1). The ACLR group was heavier than the Control group (P=.01; TABLE 1). Quadriceps strength was lower on the involved limb of the ACLR group compared to the nonpreferred limb of the Control group (mean +/- SD for ACLR group: 1.57 +/- 0.30 Nm/kg, Control group: 1.73 +/- 0.29 Nm/kg; P=.005), with no other differences in muscle strength observed between the groups (P>.05). On the modified SEBT, the ANT reach distance in the ACLR group was less than for the Control group for both the involved versus non-preferred limb (P.05) reach distances. On the involved limb, hip abduction strength was positively associated with all reach distances (ANT: r=0.31, P=.01; PM: r=0.41, P=.01; PL:


r=0.28, P=.03). In the Control group, the only significant association in the non-preferred limb was between PL reach distance and hip abduction strength (r=0.31, P=.04). DISCUSSION The results partially confirmed our a priori hypotheses. The ACLR group showed worse ANT reach performance on both the involved and uninvolved limbs compared to the Control group. There were no differences between the ACLR and Control groups in the PM and PL reach directions or in limb symmetry indices for any of the reach directions. In the ACLR group, we did not observe differences in modified SEBT performance between those with and without concomitant meniscus injuries. However, decreased PL reach distance was observed in those with patellar bone-tendon-bone grafts compared to those with hamstrings graphs, with no differences in the other reach directions. Consistent with our hypothesis, modified SEBT performance was not associated with time from surgery to testing, but was positively associated with hip abduction strength for all reach directions and with quadriceps strength for the PL direction. To our knowledge, this is the first study to evaluate performance on the modified SEBT at the time of return to sport following ACLR. Previous studies have reported the ability of the modified SEBT to differentiate performance in those with pathology, primarily chronic ankle instability, ACL deficiency, and patellofemoral pain syndrome.15, 18, 34, 38, 42, 47 While we did observe reduced ANT reach performance on the involved limb of the ACLR group compared to the Control group, we also observed reduced ANT reach performance of the uninvolved limb of the ACLR group compared to Controls. Plisky et al42 reported that an ANT reach difference between the left and right limbs of greater than 4 cm was significantly associated with risk of 11

lower extremity injury in a population of male and female high school basketball players.42 On average, the absolute difference between limbs for the ACLR group was 3.36 cm and for the Control group was 4.31 cm. Using the 4 cm or greater criteria of Plisky et al,42 33% (22/66) of the ACLR group and 38% (18/47) of the Control group demonstrated an absolute difference of


greater than 4 cm difference between limbs. For our analysis, we evaluated limb asymmetries using a limb symmetry index, a common clinical method to evaluate performance differences between the limbs.1, 14, 17, 30 The limb symmetry index of the ACLR group was 97% for the ANT reach, a value typically within the standard differences between limbs on performance tasks (85-90%).25, 31 It is unknown if a difference of 3% in limb symmetry in this screening tool is clinically meaningful in this population. Plisky et al42 did not report limb symmetry values in their study, hence it is unknown how the 4 cm or greater difference in limb performance translates into a limb symmetry index. However, an important point is that both the involved and uninvolved limbs of the ACLR group had lower ANT reach distances compared to the Control group. So, while the symmetry between the limbs for the ANT reach in the ACLR group is within appropriate performance values in the literature, the raw reach distances of both limbs are statistically lower than uninjured participants. The difference in the ANT reach between the ACLR and Control group was 5.1 cm and 4.1 cm for the involved versus non-preferred and uninvolved versus preferred limbs, respectively. Whether 4 cm is also a clinically meaningful difference between groups is unknown. Our findings are in contrast to those of Delahunt et al7 who reported worse performance on the PM and PL reaches, but no differences in the ANT reach, in females an average of 2.9 years (range from 10 months to 6 years) after ACLR compared to controls. In terms of raw values, the reach distances of the ACLR group in both studies are comparable for all 3 reach distances (Delahunt et al7/current study; ANT: 68/65 %LL; PM: 96/99 %LL; PL: 90/94 %LL). The reach distances for the Control groups were comparable as well (Delahunt et al7/current

12

study; ANT: 71/72 %LL; PM: 105/99 %LL; PL: 99/95 %LL). There are differences in sample characteristics that may relate to the difference in statistical findings (eg, sample size). In the current study, several factors may contribute to the performance of the modified SEBT in the ACLR group, relative to the Control group. The ACLR group was heavier compared


to the Control group which could have influenced their performance on the modified SEBT. For the entire cohort, weight was negatively associated with ANT reach on the involved/nonpreferred (r=-0.28, P=.003) and uninvolved/preferred (r=-0.27, P=.003) limb, with no significant associations for the PM or PL reaches. In a recent study evaluating functional outcomes following ACLR (median age 22 years), Krych et al24 reported that lower body mass index was significantly associated with an excellent 6-month functional and isokinetic outcomes. Beyond this, there is limited research examining the influence of post-surgical anthropometric factors on functional performance after ACLR, and future work in this area appears warranted. Previous studies report that quadriceps weakness is related to poor function and may persist following ACLR,6, 22, 41, 46, 54 which may impact performance on the modified SEBT. Delahunt and colleagues7 reported altered kinematic patterns during modified SEBT performance in females an average of 2.9 years following ACLR compared to controls, finding that those with ACLR demonstrated less knee flexion during all 3 reach directions. In our sample, the involved quadriceps was weaker in the ACLR group compared to Controls; however, involved quadriceps strength was only associated with PL reach distance in the ACLR group. Delahunt and colleagues7 did not report muscle strength or muscle activation data, so further comparisons cannot be made. Further study evaluating the interaction among quadriceps strength, muscle activation patterns, and kinematic patterns during the reach task will provide further insight into factors impacting the performance of the modified SEBT. Deficits in hip strength have been implicated in movement patterns associated with risk of second ACL injury following ACLR.40 Interestingly, Delahunt and colleagues7 evaluated kinematic patterns during the modified SEBT observing increased hip adduction motion during 13

performance of all 3 reach distances in their sample of ACLR participants compared to a control group. In the current study, hip abduction strength, while not different between the ACLR and Control groups, consistent with previous work,52 was positively correlated with reach distance in all 3 directions. The hip abductor muscles work to stabilize the pelvis during single leg dynamic


tasks, and previous work in healthy individuals shows gluteus medius muscle activity, as measured by surface electromyography, between 22% to 49% of an maximal volitional isometric contraction during anterior, medial, and posteromedial reaches (other directions not reported).37 Further study of the kinematic and muscle activation patterns of individuals with ACLR will provide further insight into the influence of hip abduction strength on kinematic patterns and neuromuscular control strategies during functional performance tasks. Several studies have compared outcomes between patella bone-tendon-bone and hamstring grafts with mixed findings over various times from ACLR.29, 49 The current study focuses on comparison between graft type groups on a performance-based measure of function at the time of return to sport. On the modified SEBT, the patellar bone-tendon-bone group had lower performance on the PL reach compared to the hamstring group. Given our finding that quadriceps strength was also associated with this reach direction, we further investigated the strength of these 2 sub-groups. On the involved limb, the quadriceps was weaker in the patellar bone-tendon-bone group (1.40 ± 0.26 Nm/kg) compared to the hamstring group (1.74±0.26 Nm/kg, P90%) on hop test measures at the time of return to sport.10 Further study of the


modified SEBT and other functional performance measures in active individuals with ACLR will shed light on the use of objective-based assessments to guide rehabilitation progression and return to sport decision-making. This study is not without limitations which may have influenced our findings. There are several factors that likely contribute to performance on the modified SEBT that were not evaluated in this study. In healthy individuals, available ankle dorsiflexion motion is correlated with ANT reach distance.11, 21 We did not evaluate ankle range of motion in this study and are unable to comment on the potential influence of ankle motion in our sample. Kinematic differences in hip and knee motion are noted in modified SEBT performance in those with ankle pathology12, 13 and in female athletes an average of 2.9 years post-ACLR.7 In this study, we did not analyze lower extremity movement patterns or muscle activation patterns during task performance or perform specific analyses comparing males and females, but this is a focus of our future analysis for both the ACLR and Control groups. Also, our findings in young, active individuals with ACLR at the time of return to sport may not be generalizable to patients with ACLR in different age groups or activity levels. CONCLUSION At the time of return to sport, participants who were post-ACLR demonstrated reduced modified SEBT ANT reach in both involved and uninvolved limbs compared to uninjured participants. In the ACLR group, modified SEBT reach distance is associated with lower extremity muscle strength, but not with time from reconstruction or meniscal status at the time of ACLR. Lower extremity muscle strength and graft type may interact to influence modified SEBT posterior reach performance but this requires further study. 16

KEY POINTS Findings: At the time of return to sport, individuals post-ACLR demonstrate reduced modified SEBT ANT reach in both involved and uninvolved limbs compared to uninjured individuals. In the ACLR group, modified SEBT reach distances are associated with lower extremity muscle


strength, but not with time from reconstruction or meniscal status at the time of ACLR. Implications: It is unknown if observed differences in the ACLR group relative to uninjured individuals represent a clinically meaningful difference in performance. Caution: There are several factors that likely contribute to performance on the modified SEBT that were not evaluated in this study. These findings in young, active individuals with ACLR at the time of return to sport may not be generalizable to all patients following ACLR.

Acknowledgements We would like to thank the staff at the staff at the Sports Medicine Biodynamics Center, specifically Staci Thomas, and the Sports and Orthopaedic Team in the Division of Occupational Therapy and Physical Therapy at Cincinnati Children’s Hospital Medical Center for their contributions to this work.

17

1

TABLE 1. Participant characteristics*


ACLR Group n=66 17.6 +/-2.9 69.4 +/-16.3 168.8 +/-8.8 90.4 +/-5.4 90.4 +/-5.4

2 3 4 5 6

Control Group n=47 17.0 +/-2.3 62.5 +/-12.6 167.4 +/-9.3 89.3 +/-5.5 89.0 +/-5.5

P-value

Age (years) Weight (kg) Height (cm) Right leg length (cm) Left leg length (cm) Sex (n) Female 46 32 Male 20 15 * Data are mean +/- standard deviation except for sex.

.21 .01 .42 .29 .20 .85

TABLE 2. Characteristics and functional outcome measures for those with ACLR.* ACLR Group Graft Type (n) PT-BTB HS Allograft Time from surgery (mos)

7 8 9 10 11 12 13 14 15 16

IKDC (0-100) Hop Test LSI (%) Single hop 94 +/-7 Triple hop 95 +/-7 Crossover hop 94 +/-9 Timed hop 97 +/-8 Abbreviations: ACLR, anterior cruciate ligament reconstruction; HS, hamstring autograft; IKDC, International Knee Documentation Committee subjective knee form score; LSI, limb symmetry index calculated as ratio of involved and uninvolved performance *100%; PT-BTB, patellar bone-tendon-bone autograft. *Data are mean +/- standard deviation unless otherwise indicated.

TABLE 3. Performance on the Modified SEBT for subsets of the ACLR group Sub-group Comparisons By Graft Type PT-BTB HS By Meniscus Injury ACLR+m ACLR

17 18 19 20 21 22

n=26 n=32 n=8 6.7 +/-1.6 (range: 4.2-11.1) 85.8 +/-10.9

ANT

PM

PL

63.9 +/-7.2 66.7 +/-9.1 P=.21

97.5 +/-11.8 100.6 +/-13.8 P=.36

90.4 +/-13.7 97.5 +/-8.3 P=.02*

65.1 +/-7.1 65.5 +/-8.9 P=.83

98.8 +/-15.7 99.0 +/-9.6 P=.96

92.1 +/-12.5 95.9 +/-9.7 P=.17

Abbreviations: ACLR, individuals with ACLR and no meniscus injury; ACLR+m, individuals with ACLR and concomitant meniscus injury; ANT, anterior; HS, hamstring autograft; LL, leg length; PM, posteromedial; PL, posterolateral; PT-BTB, patellar bone-tendon-bone autograft; *Data are mean +/- standard deviation in %LL

18


23 24 25 26 27 28 29 30

FIGURE 1. Performance of the modified star excursion balance test (SEBT) on the left lower extremity. For the test, each participant stands in single limb stance on the test limb and performs maximal reaches with the non-stance limb in the anterior (ANT) (left), posteromedial (PM) (middle) and posterolateral (PL) (right) directions.

31

19


32 33 34 35 36 37 38 39 40

FIGURE 2. Mean +/- standard deviations reach distances for all reach directions for both limbs of the ACLR and Control groups. There was a main effect for group in the anterior reach direction with the ACLR group having lower reach distances than the Control group for both lower extremities. A statistically significant difference was observed for the anterior direction only (P

Y BALANCE TEST™ ANTERIOR REACH SYMMETRY AT THREE MONTHS IS RELATED TO SINGLE LEG FUNCTIONAL PERFORMANCE AT TIME OF RETURN TO SPORTS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION.

Return to work in miners following anterior cruciate ligament reconstruction.

Strength Asymmetry and Landing Mechanics at Return to Sport after Anterior Cruciate Ligament Reconstruction.

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Return to sport after anterior cruciate ligament reconstruction in professional soccer players.

An Ecological Study of Anterior Cruciate Ligament Reconstruction, Part 2: Functional Performance Tests Correlate With Return-to-Sport Outcomes.

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The influence of quadriceps strength asymmetry on patient-reported function at time of return to sport after anterior cruciate ligament reconstruction.

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REPRODUCIBILITY OF THE MODIFIED STAR EXCURSION BALANCE TEST COMPOSITE AND SPECIFIC REACH DIRECTION SCORES.

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Knee contact force asymmetries in patients who failed return-to-sport readiness criteria 6 months after anterior cruciate ligament reconstruction.

Increased Compliance With Supervised Rehabilitation Improves Functional Outcome and Return to Sport After Anterior Cruciate Ligament Reconstruction in Recreational Athletes.

Editorial: Functional testing in the assessment of return to sports after anterior cruciate ligament reconstruction.

Factors affecting return to play after anterior cruciate ligament reconstruction: a review of the current literature.

[Reconstruction of the anterior cruciate ligament].

Reconstruction of the anterior cruciate ligament.

Contributing factors to star excursion balance test performance in individuals with chronic ankle instability.

Quadriceps Strength Asymmetry After Anterior Cruciate Ligament Reconstruction Alters Knee Joint Biomechanics and Functional Performance at Time of Return to Activity.

Athletic Performance at the National Basketball Association Combine After Anterior Cruciate Ligament Reconstruction.

Tibial cyst formation following anterior cruciate ligament reconstruction.