Effects of Blood Flow Restriction on Balance Performance During Dynamic Balance Exercises in Individuals With Chronic Ankle Instability.

CONTEXT: Blood flow restriction (BFR) is a rehabilitation tool which may introduce a constraint, similar to muscle fatigue, that challenge patients' sensorimotor system during balance exercises. The purpose of our study was to examine whether adding BFR to dynamic balance exercises produced a decrease in balance performance and an increase in ratings of perceived exertion and instability in individuals with chronic ankle instability (CAI) compared with dynamic balance exercises without BFR. DESIGNS: Crossover design. METHODS: Our sample included N = 25 young adults with a history of CAI. Participants completed 2 laboratory visits. At each visit, participants completed 4 sets (30×-15×-15×-15×) of dynamic balance exercises, performed similar to the modified star excursion balance test (SEBT), once with BFR and once with control (no BFR) conditions. We measured composite SEBT scores at baseline and during the final repetitions of each set of balance exercise (sets 1-4). We also measured ratings of perceived exertion and instability following each balance exercise set. RESULTS: We observed no difference in composite SEBT scores between conditions at baseline; however, composite SEBT scores were significantly lower during all balance exercises sets 1 to 4 with the BFR condition compared with control. During the BFR condition, composite SEBT scores were significantly lower during all balance exercise sets compared with baseline. During the control condition, composite SEBT scores did not significantly change between baseline and each balance exercise set. Ratings of perceived exertion and instability scores were significantly greater in the BFR group compared with the control group during all balance exercise sets. CONCLUSIONS: Individuals with CAI demonstrated lower composite SEBT scores and greater perceived instability and exertion during dynamic balance exercise with BFR compared to without BFR. BFR introduced a novel muscle fatigue constraint during dynamic balance exercises in individuals with CAI. Additional research is needed to determine if adding BFR to balance training could improve clinical outcomes in CAI patients.

Exploration of the Golf-Specific Low Back Pain Questionnaire.

OBJECTIVE: The primary purpose of this study was to determine internal consistency and concurrent validity of the Golf-specific Low Back Pain questionnaire (GLBP). DESIGN: Cross-sectional study. SETTING: Online questionnaire. PARTICIPANTS: Fifty-two adult golfers with a history of LBP. INTERVENTIONS: GLBP, Oswestry Disability Index (ODI). MAIN OUTCOME MEASURES: Cronbach alpha values for the GLBP and its 3 subscales. Pearson correlations between the ODI, GLBP, and the GLBP subscales. RESULTS: Cronbach alpha for the GLBP was 0.94. Cronbach alpha for the 3 GLBP subscales ranged from 0.85 to 0.91. All Pearson correlations were significant at P < 0.05. The correlation between the ODI and GLBP was -0.64, and correlations between the ODI and GLBP subscales ranged from -0.53 to -0.63. Mean GLBP score was 72.01% ± 16.15%, and mean ODI score was 12.00% ± 7.98%. CONCLUSIONS: The GLBP has excellent concurrent validity to quantify LBP in golfers. The GLBP total and each individual subscale have excellent internal consistency and a moderate inverse relationship with the ODI. The GLBP offers a more sport-specific patient-reported outcome measure for this population. The GLBP may more adequately quantify LBP-related disability, especially at lower levels of disability. Findings provide initial evidence that the GLBP may be a valid tool to quantify LBP symptoms and dysfunction in golfers. CLINICAL RELEVANCE: Clinicians should consider using sport-specific outcome measures when evaluating for LBP-related disability.

Youth sport specialization associated with poorer lower extremity function & pain as young adults.

OBJECTIVE: Examine the link between youth sports specialization and long-term lower extremity joint health after sports by comparing lower extremity function, pain, and history of sport-related injuries between young adults that were highly, moderately, and low specialized in youth sports. METHODS: We used a cross-sectional design, and all data was collected using an electronic survey. Our sample included N = 356 young adults who participated in a primary sport during youth and high school sports but were no longer participating in that sport as a young adult. Participants were stratified into high (n = 111), moderate (n = 119), and low (n = 126) specialization groups using a 3-criteria sport specialization questionnaire based on youth sports participation prior to high school. We compared participants current Lower Extremity Functional Scale (LEFS) score (0-80), the proportion of participants with clinically important deficits in LEFS score (≤71/80), current lower extremity (foot/ankle, knee, hip) pain scores (0-10), and history of lower extremity (foot/ankle, knee, hip) injuries between the high, moderate, and low specialization groups. RESULTS: The high specialization group reported significantly lower overall LEFS scores, and a greater proportion (40%) reported clinically important deficits in LEFS scores compared to the low specialization group (20%). The high specialization group also reported greater foot/ankle and knee pain and a greater proportion of sport-related knee injuries than the low specialization group (49% vs 25%). CONCLUSIONS: Our findings suggest that even after discontinuing sports, young adults who were highly specialized in youth sports before high school reported clinically important deficits in lower extremity function, greater foot/ankle and knee pain, and a greater history of knee injuries than young adults who were not specialized in youth sports, suggesting a possible link between youth sports specialization and long-term lower extremity health after sports.

Instrumented measures of postural control in college dancers with and without chronic ankle instability.

OBJECTIVES: To determine whether collegiate dancers with chronic ankle instability (CAI) demonstrated impaired postural control during instrumented measures of single-leg static balance compared to dancers without CAI. DESIGN: Cross sectional design. SETTING: University dance studios. PARTICIPANTS: We included N = 39 dance majors from a large, public university. We stratified participants into CAI (n = 20, age = 20 ± 1.8, IdFAI = 17.3 ± 5.7, number of sprains = 1.9 ± 1.1) and Control groups (n = 19, age = 20 ± 1.2, IdFAI = 2.5 ± 3.0). MAIN OUTCOME MEASURES: Participants performed 3 x 10-s single-leg, static balance trials on a pressure mat in two different conditions, foot-flat eyes closed and demi-pointe eyes open. We measured six different time-to-boundary (TTB) measurements during each balance trial and calculated the average of the 3 trials for each condition. Participants also completed the Foot and Ankle Ability Measure (FAAM) sport and activities of daily living (ADL) questionnaires. RESULTS: The CAI group reported greater IdFAI and lower FAAM-ADL and FAAM-Sport scores compared to the control group. We observed no significant differences in TTB measurements between the CAI and control groups during either balance conditions. CONCLUSIONS: Instrumented measures of static postural control were not impaired in college dancers with CAI compared dancers without CAI.

Early Sport Specialization Linked to Throwing Arm Function and Upper Extremity Injury History in College Baseball Players.

BACKGROUND: Evidence suggests that shoulder and elbow injuries account for 31% to 37% of all National Collegiate Athletic Association (NCAA) baseball injuries, and up to 69% of NCAA baseball injuries are the result of noncontact and overuse mechanisms. Early sport specialization may contribute to the high rates of upper extremity injuries in college baseball players. HYPOTHESIS: Higher specialization by age 13 years would be associated with worse subjective throwing arm function and a greater history of shoulder and elbow injury. STUDY DESIGN: Cohort study. LEVEL OF EVIDENCE: Level 2. METHODS: Survey data were collected from college baseball players (N = 129) during midseason of the spring 2019 baseball season. Participants were stratified in low, moderate, and high specialization groups based on a 3-criteria sports specialization questionnaire. Participants' throwing arm function was measured using the Functional Arm Scale for Throwers and the Kerlan-Jobe Orthopaedic Clinic shoulder and elbow questionnaires. Participants' history of a shoulder or elbow injury that resulted in missing ≥2 weeks of baseball activity at any point in their baseball career was also collected. RESULTS: The high specialization group reported worse subjective throwing arm function on the Functional Arm Scale for Throwers questionnaire than the low (P = 0.03) and moderate (P = 0.01) specialization groups. The high specialization group was over 5 times more likely to report a history of shoulder injury than the moderate (odds ratio [OR] = 5.42; 95% CI [1.71, 17.2]; P = 0.004) and low (OR = 5.20; 95% CI [1.87, 14.5]; P = 0.002) specialization groups, and over 3 times more likely to report a history of elbow injury than the moderate specialization group (OR = 3.77; 95% CI [1.05, 13.6]; P = 0.04). CONCLUSION: College baseball players that were highly specialized by age 13 years reported worse subjective throwing arm function and were more likely to have a history of upper extremity injury than players that were moderate or low specialization. CLINICAL RELEVANCE: Early specialization in baseball may be detrimental to long-term upper extremity health in college baseball players.

Effects of Blood Flow Restriction on Muscle Activation During Dynamic Balance Exercises in Individuals With Chronic Ankle Instability.

CONTEXT: Dynamic balance exercises are commonly utilized during ankle sprain and chronic ankle instability (CAI) rehabilitation. Blood flow restriction (BFR) has been used to enhance muscle activity during exercise and improve outcomes of traditional rehabilitation exercises in clinical populations. OBJECTIVE: Examine the effects of BFR on lower-extremity muscle activation during dynamic balance exercises in individuals with CAI. DESIGN: Crossover study design. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-five (N = 25) young adults with a history of CAI. INTERVENTIONS: Participants performed dynamic balance reaching exercises during 2 randomized order conditions, BFR, and control. For each condition, participants performed 2 trials of balance exercises. Each trial included 4 sets (30 × 15 × 15 × 15) of reaches in anterior, posteromedial, and posterolateral directions. For the BFR condition, the authors placed a cuff around the proximal thigh at 80% of arterial occlusion pressure. For the control condition, no cuff was worn. MAIN OUTCOME MEASURE(S): The authors recorded normalized electromyography muscle activation of the vastus lateralis, soleus, tibialis anterior, and fibularis longus during balance exercise trials and recorded participants' ratings of perceived postural instability and exertion after each trial of balance exercises. RESULTS: The authors observed greater vastus lateralis (P < .001, d = 0.86 [0.28 to 1.44]) and soleus (P = .03, d = 0.32 [-0.24 to 0.87]) muscle activation during balance exercises with BFR than control. The authors observed no differences in tibialis anterior (P = .33, d = 0.09 [-0.46 to 0.65]) or fibularis longus (P = .13, d = 0.06 [-0.50 to 0.61]) muscle activation between the conditions. The authors observed greater ratings of perceived postural instability (P = .004) and exertion (P < .001) during balance exercises with BFR than control. CONCLUSIONS: Individuals with CAI demonstrated large increases in vastus lateralis and small increases in soleus muscle activation during dynamic balance exercises with BFR. The BFR had no effect on fibularis longus and tibialis anterior muscle activation. Individuals with CAI perceived greater postural instability and exertion during dynamic balance exercises with BFR.

Influence of Patient Demographics and Surgical Characteristics on Pass Rates of Return-to-Activity Tests in Anterior Cruciate Ligament-Reconstructed Patients Before Physician Clearance.

OBJECTIVE: To identify the frequency of passing return-to-activity tests after anterior cruciate ligament reconstruction (ACLR) and to investigate the influence of patient-specific factors on pass rates. We hypothesized that isolated strength tests would be most difficult to pass and that graft type would be the most influential factor. DESIGN: Cross-sectional. SETTING: Laboratory. PARTICIPANTS: Eighty patients with a history of primary, unilateral ACLR, and 80 healthy controls participated. INTERVENTIONS: Bilateral isokinetic strength, isometric strength, and single-leg hop tests were recorded during a single visit. The International Knee Documentation Committee (IKDC) Subjective Knee Evaluation measured subjective knee function, and the Tegner Activity Scale measured physical activity level. MAIN OUTCOME MEASURES: Pass rates were calculated for 3 thresholds of absolute between-limb asymmetry: 0% to 10%, 11% to 15%, and 16% to 20%. Pass rates were compared by sex (male and female), graft type (patellar and hamstrings), meniscal procedure (yes and no), physical activity level (

Effect of Grade and Surface Type on Peak Tibial Acceleration in Trained Distance Runners.

Runners experience repeated impact forces during training, and the culmination of these forces can contribute to overuse injuries. The purpose of this study was to compare peak vertical tibial acceleration (TA) in trained distance runners on 3 surface types (grass, asphalt, and concrete) and 3 grades (incline, decline, and level). During visit 1, subjects completed a 1-mile time trial to determine their pace for all running trials: 80% (5%) of the average time trial velocity. During visit 2, subjects were outfitted with a skin-mounted accelerometer and performed 18 separate running trials during which peak TA was assessed during the stance phase. Each subject ran 2 trials for each condition with 2 minutes of rest between trials. Peak TA was different between decline (8.04 [0.12] g) and incline running (7.31 [0.35] g; P = .020). On the level grade, peak TA was greater during grass (8.22 [1.22] g) compared with concrete (7.47 [1.65] g; P = .017). On the incline grade, grass (7.68 [1.44] g) resulted in higher peak TA than asphalt (6.99 [1.69] g; P = .030). These results suggest that under certain grade conditions grass may result in higher TA compared with either concrete or asphalt.

Transverse abdominis activity and ultrasound biofeedback in college golfers with and without low back pain.

OBJECTIVES: To compare transverse abdominis (TrA) muscle activity in college golfers with and without a history of low back pain (LBP) and examine the effects of ultrasound biofeedback and a functional golf-setup position on TrA activity. DESIGN: Crossover study. SETTING: Laboratory. PARTICIPANTS: Thirty-two (n = 32) collegiate golfers were stratified into either the LBP group (n = 16, 4.6 ± 4.5 LBP episodes) or non-LBP group (n = 16, 0.1 ± 0.3 LBP episodes) based on LBP episodes in the last 6-months. MAIN OUTCOME MEASURES: Ultrasound measures of TrA activity were performed during standard contractions and contractions with ultrasound biofeedback. Contraction-type order was randomized between two visits. Testing was performed in two positions, supine and golf-setup positions. RESULTS: We observed no significant differences in TrA activity between the LBP and non-LBP groups. Overall, TrA activity was greater during biofeedback contractions compared to standard contractions, and TrA activity was lower in the golf-setup position compared to the supine position. CONCLUSIONS: We observed no differences in TrA activity between college golfers with and without LBP. College golfers with and without LBP demonstrated a greater ability to contract their TrA with real-time ultrasound biofeedback and a lower ability to contract their TrA in the functional golf-setup position compared to the traditional supine position.

Test-Retest Reliability and the Effects of Exercise on the King-Devick Test.

OBJECTIVE: To determine the test-retest reliability and the influence of exercise on King-Devick (K-D) test performance. DESIGN: Crossover study design. SETTING: Controlled laboratory. PARTICIPANTS: Participants consisted of 63 (39 women and 24 men) healthy, recreationally active college students who were 21.0 + 1.5 years of age. INDEPENDENT VARIABLES: Participants completed the K-D test using a 2-week, test-retest interval. The K-D test was administered before and after a counterbalanced exercise or rest intervention. Reliability was assessed using testing visits (visit 1 and visit 2) as the independent variables. Exercise or rest and time (baseline, postintervention) were used as independent variables to examine the influence of exercise. MAIN OUTCOME MEASURES: Intraclass correlation (ICC) coefficients with 95% confidence intervals were calculated between visits to assess reliability of K-D test completion time. A repeated-measure 2 x 2 analysis of variance (intervention × time) with post hoc paired t tests was used to assess the influence of exercise on K-D test performance. RESULTS: The K-D test was observed to have strong test-retest reliability [ICC2,1 = 0.90 (0.71, 0.96)] over time. No significant intervention-by-time interaction (P = 0.55) or intervention main effects (P = 0.68) on K-D time were observed. Mean differences of -1.5 and -1.7 seconds (P < 0.001) were observed between baseline and rest and exercise interventions for K-D test performance, respectively. Up to 32% (20/63) of participants were observed to have a false-positive K-D test performance before and after each intervention. CONCLUSIONS: Although strong test-retest reliability coefficients were observed using clinically relevant time points, a high false-positive rate warrants caution when interpreting the K-D test.

Early Sport Specialization and Subjective Hip and Groin Dysfunction in Collegiate Ice Hockey Athletes.

CONTEXT: Sport specialization is a popular trend among youth athletes that has been associated with an increased risk for developing lower extremity overuse injuries. Early ice hockey specialization may contribute to the high rates of noncontact and overuse hip and groin injuries in collegiate ice hockey athletes. OBJECTIVE: To examine the effects of high, moderate, and low levels of sport specialization on subjective hip and groin dysfunction in collegiate ice hockey athletes. DESIGN: Retrospective cohort study. SETTING: Data were collected during the midseason of the 2018-2019 hockey season at a local ice hockey arena. PATIENTS OR OTHER PARTICIPANTS: National Collegiate Athletic Association Division III and club ice hockey players from Midwestern college programs (n = 187; 81 women, 106 men). MAIN OUTCOME MEASURE(S): Participants were stratified into high-, moderate-, and low-specialization groups based on ice hockey participation before grade 9 of high school. The 6 subscales of the Hip and Groin Outcome Score questionnaire were used to assess current subjective hip and groin dysfunction. RESULTS: The high-specialization group had lower scores than the low-specialization group on the Symptoms (P = .001), Pain (P = .003), Activities of Daily Living (P = .001), Sport and Recreation (P = .014), and Quality of Life (P = .002) subscales. The moderate-specialization group had lower scores than the low-specialization group on the Symptoms (P = .015) and Activities of Daily Living (P = .006) subscales. CONCLUSIONS: Collegiate ice hockey athletes who were highly specialized before high school reported greater current hip and groin pain, symptoms, and dysfunction during activities of daily living and sport and recreation and lower current hip- and groin-related quality of life compared with low-specialization ice hockey athletes. Early ice hockey specialization may be detrimental to hip and groin function in collegiate ice hockey athletes.

The Effects of Blood Flow Restriction on Muscle Activation and Hypoxia in Individuals With Chronic Ankle Instability.

CONTEXT: Muscle dysfunction is common in patients with chronic ankle instability (CAI). Blood flow restriction (BFR) may enhance muscle responses during exercise and provide an opportunity to enhance muscle adaptations to ankle rehabilitation exercises; however, there is no evidence examining the effect of BFR on muscle function in CAI patients. OBJECTIVE: Examine the effects of BFR on muscle activation and oxygen saturation during submaximal ankle eversion and dorsiflexion exercises in individuals with CAI. DESIGN: Cross-over study design. SETTING: Laboratory setting. Patients (or Other Participants): Nineteen young adults with a history of CAI. INTERVENTIONS: Participants performed 4 sets (30, 15, 15, and 15) of eversion and dorsiflexion resistance exercises at 30% of maximum voluntary isometric contraction during 2 conditions, BFR and control. For BFR, a cuff was applied above the knee at 80% of blood flow occlusion. For control, the cuff was not inflated. MAIN OUTCOME MEASURES: Fibularis longus and tibialis anterior electromyography muscle activation, lower-leg muscle oxygen saturation, and ratings of perceived exertion were recorded during exercises. RESULTS: Average grand mean muscle activation was 5.6% greater during eversion (P = .03) and 7.7% greater during dorsiflexion (P = .01) resistance exercises with BFR compared with control; however, the magnitudes of the effects of BFR were only clinically important during the dorsiflexion exercises. Lower-leg muscle oxygen saturation was 31% to 44% lower (P < .001) during BFR exercises. Ratings of perceived exertion were significantly higher during BFR exercises (P < .001). CONCLUSIONS: Greater muscle activation and hypoxia were present during submaximal resistance exercise with BFR in participants with CAI. Greater muscle activation and hypoxia during BFR exercises may be important acute responses mediating the training-related muscle adaptations that have been observed with BFR. The presence of these acute responses in CAI patients supports further research examining BFR as a potential ankle rehabilitation tool.

The effects of patellar tendon vibration on quadriceps strength in anterior cruciate ligament reconstructed knees.

OBJECTIVES: To examine the immediate effects of prolonged patellar tendon vibration on quadriceps strength in anterior cruciate ligament reconstructed (ACLR) knees with bone-patellar tendon-bone (BTB) grafts and non-BTB grafts, and healthy control knees. DESIGN: Pretest-posttest design. SETTING: Laboratory. PARTICIPANTS: Young adult participants were stratified into one of three groups: non-BTB graft (n = 25), BTB graft (n = 26), and controls without ACLR (n = 21). MAIN OUTCOME MEASURES: Maximum voluntary isometric contraction (MVIC) knee extension torque was measured at baseline and following a 20-min vibration intervention applied locally to the patellar tendon. RESULTS: Our findings suggest there was no difference in the effects of vibration on knee extension torque between the three groups. Knee extension torque significantly increased (effect size = 0.52 [0.18 to 0.81]) from baseline to post-vibration across all three groups (0.30 ±â€¯0.26 Nm/kg, 21.8 ±â€¯20.0%). Both ACLR groups demonstrated significantly lower knee extension torque compared the control group. CONCLUSIONS: The vibration intervention had a net excitatory effect on quadriceps strength in all three groups and there were no differences in the magnitude of change between the three groups. Vibration could become a useful tool for enhancing quadriceps strength in ACLR and healthy knees.

The relationships between kinesiophobia and clinical outcomes after ACL reconstruction differ by self-reported physical activity engagement.

OBJECTIVES: To investigate whether relationships between kinesiophobia, lower extremity function, and patient-reported function differ by self-reported physical activity engagement after ACL reconstruction (ACLR). DESIGN: Cross-sectional. SETTING: Laboratory. PARTICIPANTS: Seventy-seven patients with a primary, unilateral ACLR. MAIN OUTCOME MEASURES: Kinesiophobia (TSK-17) was the primary outcome. Lower extremity function included quadriceps and hamstrings strength, fatigue, and hop performance. Patient-reported function included regional function (IKDC, KOOS subscales) and physical activity engagement (Godin Leisure-Time Exercise). Patients were evaluated together, then stratified by LOW and HIGH physical activity. Correlations and multiple regression analyses identified relationships between kinesiophobia and outcome measures. RESULTS: Greater kinesiophobia was associated with lesser hamstrings strength, hop performance, and patient-reported function. Greater hamstrings fatigue and lesser KOOSADL explained greater kinesiophobia in patients reporting LOW physical activity. Lesser triple hop symmetry, crossover hop distance, and IKDC explained greater kinesiophobia in patients reporting HIGH physical activity. CONCLUSIONS: Greater kinesiophobia associated with worse outcomes after ACLR. Relationships differed by self-reported physical activity engagement. Interventions that improve the ability to perform knee-related activities of daily living may be appropriate to minimize the impact of fear in less active patients, while those targeting hop performance and knee-related sport activities may be better suited for more active patients.

Relationship Between Physical Therapy Characteristics, Surgical Procedure, and Clinical Outcomes in Patients After ACL Reconstruction.

CONTEXT: Postoperative rehabilitation is critical to optimize outcomes after anterior cruciate ligament reconstruction (ACLR). However, the relationship between physical therapy (PT) and clinical outcomes is unclear. OBJECTIVE: To describe PT characteristics following ACLR and to assess the relationships between PT characteristics, surgical procedure, and clinical outcomes. DESIGN: Cross-sectional. SETTING: Laboratory. Patients (or Other Participants): A total of 60 patients (31 females/29 males, age = 22.4 [9.2] y, height = 171.7 [9.9] cm, and mass = 70.2 [14.7] kg) with a history of primary unilateral ACLR (53.6% patellar tendon and 46.4% hamstring) participated. INTERVENTION(S): Patients completed a performance assessment and rated subjective knee function prior to physician clearance (mean = 6.3 [1.3] mo postoperatively) and were contacted within 6 months of clearance to complete a PT questionnaire. MAIN OUTCOME MEASURES: PT questionnaire item response, knee extension maximum voluntary isometric contraction (MVIC) torque, peak isokinetic knee extension torque, single leg hop distance, and International Knee Documentation Committee were measured. Correlations assessed relationships between PT quantity and clinical outcomes. Independent t tests compared PT quantity and clinical outcomes based on return-to-sport status, readiness to return to sport, and surgical procedure. RESULTS: Patients completed regular PT (2 d/wk, 25 wk, 58 visits) and were most likely to conclude when discharged by the therapist (68.3%). More than half (56.7%) returned to sport, yet most (73.3%) felt unready at discharge. Isokinetic torque was correlated with days of PT/week (r = .29, P = .03). Isokinetic torque and hop symmetry were reduced in patients who returned to sport (P < .05). Patients who felt ready to return completed fewer weeks of PT (P < .05). Patients with a patellar tendon graft completed more days of PT/week and total visits, but demonstrated lower MVIC torque, MVIC symmetry, and isokinetic symmetry (P < .05). CONCLUSIONS: Many patients felt unready to return to sport at PT discharge. PT frequency was associated with isokinetic torque, yet this relationship was small. Outcomes were reduced in patients who returned to sport, suggesting premature resumption of preinjury activity.

ACL reconstructed individuals do not demonstrate deficits in postural control as measured by single-leg balance.

BACKGROUND: Following anterior cruciate ligament reconstruction (ACLR), patients undergo a battery of performance assessments to determine progression of return to sport activity. Rates of reinjury following ACLR are high, indicating that current assessments may not accurately identify deficits at the time point of return to sport progression. RESEARCH QUESTION: To assess single-leg postural control in ACLR patients around the time point of return to sport progression and their relationships to subjective function. STUDY DESIGN: Descriptive Laboratory Study. METHODS: 198 individuals (108 ACLR, 90 healthy) participated. All ACLR participants were at the time point of return to play progression. Postural stability was quantified by center of pressure (COP) average velocity measured through a straight-knee single-leg balance assessment for 10-seconds with the participant's eyes closed. Subjective knee function was measured from the International Knee Documentation Committee (IKDC) Subjective Knee Form and the Knee Osteoarthritis Outcome Score (KOOS) subscales. RESULTS: No significant differences existed between COP average velocity between limbs (uninvolved, involved) or groups (ACLR, Healthy). As a secondary aim, no significant relationships existed between measures of subjective knee function and postural stability. SIGNIFICANCE: Individuals following ACLR demonstrate similar patterns of postural stability as healthy individuals in a straight knee single leg balance task. Single-leg balance in a straight knee position may not be sensitive enough to detect impairments and does not predict subjective function in ACLR patients at the time of return to sport progression.

Gait Biomechanics in Anterior Cruciate Ligament-reconstructed Knees at Different Time Frames Postsurgery.

PURPOSE: To examine knee and hip biomechanics during walking and jogging in groups of ACLR patients at early, mid, and late time frames postsurgery and healthy controls. METHODS: Participants included individuals with a history of primary, unilateral ACLR, stratified into early (1.4 ± 0.4 yr post, n = 18), mid (3.3 ± 0.6 yr post, n = 20), and late (8.5 ± 2.8 yr post, n = 20) ACLR groups based on time postsurgery, and a healthy control group (n = 20). Walking and jogging motion capture analysis of knee and hip kinetics and kinematics were measured in the sagittal and frontal planes. Interlimb (within groups) and between-group comparisons were performed for all gait variables. Statistical comparisons were made across the gait cycle by plotting graphs of means and 90% confidence intervals and identifying regions of the gait cycle in which the 90% confidence intervals did not overlap. RESULTS: Early ACLR group demonstrated reduced knee flexion, knee extension, knee adduction, and hip adduction moments on the ACLR limb. Mid ACLR group demonstrated no gait differences between limbs or other groups. Late ACLR group demonstrated reduced knee flexion moments, and greater knee and hip adduction moments in their ACLR limb. Control group demonstrated no interlimb differences. CONCLUSIONS: Walking and jogging gait biomechanics presented differently in patients at different stages in time after ACLR surgery. The early ACLR group demonstrated lower sagittal and frontal plane joint loading on the ACLR limb compared with contralateral and control limbs. The mid ACLR group did not demonstrate any gait differences compared with the contralateral or control limb. The late ACLR group demonstrated lower sagittal plane joint loading compared with control limbs and greater frontal plane joint loading compared to contralateral and control limbs.

Validating Center-of-Pressure Balance Measurements Using the MatScan® Pressure Mat.

CONTEXT: Measurements of center-of-pressure (COP) excursions during balance are common practice in clinical and research settings to evaluate adaptations in postural control due to pathological or environmental conditions. Traditionally measured using laboratory force plates, pressure-mat devices may be a suitable option for clinicians and scientist to measure COP excursions. OBJECTIVE: Compare COP measures and changes during balance between MatScan® pressure mat and force plate. DESIGN: Validation study. SETTING: Laboratory. PARTICIPANTS: 30 healthy, young adults (19 female, 11 male, 22.7 ± 3.4 y, 70.3 ± SD kg, 1.71 ± 0.09 m). MAIN OUTCOMES: COP excursions were simultaneously measured using pressure-mat and force-plate devices. Participants completed 3 eyes-open and 3 eyes-closed single-leg balance trials (10 s). Mean of the 3 trials was used to calculate 4 COP variables: medial-lateral and anterior-posterior excursion, total distance, and area with eyes open and eyes closed. Percent change and effect sizes were calculated between eyes-open to eyes-closed conditions for each variable and for both devices. RESULTS: All COP variables were highly correlated between devices for eyes-open and eyes-closed conditions (all r > .92, P < .001). Bland-Altman plots suggest the pressure-mat COP measurements were smaller than those of the force-plate, and the differences between devices appeared to increase as the measurement magnitude increased. Percent change in COP variables was highly correlated between devices (r > .85, P < .001). Cohen d effect sizes between eyes-open and eyes-closed were all large (d > 2.25) and similar in magnitude between devices. CONCLUSION: COP measures were correlated between devices, but values tended to be smaller using the pressure mat. The pressure mat and force plate detected comparable magnitude changes in COP measurements between eyes-open and eyes-closed. Pressure mats may provide a viable option for detecting large magnitude changes in postural control during short-duration testing.

Relationships of Functional Tests Following ACL Reconstruction: Exploratory Factor Analyses of the Lower Extremity Assessment Protocol.

CONTEXT: After ACL reconstruction (ACLR), deficits are often assessed using a variety of functional tests, which can be time consuming. It is unknown whether these tests provide redundant or unique information. OBJECTIVE: To explore relationships between components of a battery of functional tests, the Lower Extremity Assessment Protocol (LEAP) was created to aid in developing the most informative, concise battery of tests for evaluating ACLR patients. DESIGN: Descriptive, cross-sectional. SETTING: Laboratory. PARTICIPANTS: 76 ACLR patients (6.86±3.07 months postoperative) and 54 healthy participants. INTERVENTION: Isokinetic knee flexion and extension at 90 and 180 degrees/second, maximal voluntary isometric contraction for knee extension and flexion, single leg balance, 4 hopping tasks (single, triple, crossover, and 6-meter timed hop), and a bilateral drop vertical jump that was scored with the Landing Error Scoring System (LESS). MAIN OUTCOME MEASURES: Peak torque, average torque, average power, total work, fatigue indices, center of pressure area and velocity, hop distance and time, and LESS score. A series of factor analyses were conducted to assess grouping of functional tests on the LEAP for each limb in the ACLR and healthy groups and limb symmetry indices (LSI) for both groups. Correlations were run between measures that loaded on retained factors. RESULTS: Isokinetic and isometric strength tests for knee flexion and extension, hopping, balance, and fatigue index were identified as unique factors for all limbs. The LESS score loaded with various factors across the different limbs. The healthy group LSI analysis produced more factors than the ACLR LSI analysis. Individual measures within each factor had moderate to strong correlations. Isokinetic and isometric strength, hopping, balance, and fatigue index provided unique information. CONCLUSIONS: Within each category of measures, not all tests may need to be included for a comprehensive functional assessment of ACLR patients due to the high amount of shared variance between them.

Relationships of Muscle Function and Subjective Knee Function in Patients After ACL Reconstruction.

BACKGROUND: After anterior cruciate ligament reconstruction (ACLR), relationships between objective measures of muscle function and patient-reported outcomes may change over time. Examining these measures at different time frames after surgery may help develop individualized approaches to improve post-ALCR analysis. PURPOSE: To examine the associations between subjective knee function and lower-extremity muscle function in individual patients at various time points after ACLR. STUDY DESIGN: Descriptive laboratory study. METHODS: Fifty-one participants who underwent primary, unilateral ACLR (15 males, 36 females; mean age, 22.9 ± 4.5 years; mean height, 172.4 ± 10.1 cm; mean weight, 68.7 ± 13.1 kg) were separated into 3 groups depending on time since surgery (early, <2 years; middle, 2-5 years; late, >5 years). Subjective knee function was quantified using the International Knee Documentation Committee (IKDC) subjective knee form and the Knee injury and Osteoarthritis Outcome Score (KOOS). Isometric knee extension and flexion strength were collected at 90 deg/s. Single-leg hop performance was measured using the single hop, triple hop, cross-over hop, and 6-m timed hop. Coefficient correlations were calculated between subjective knee function and objective measures of muscle function for each group. RESULTS: The early group demonstrated moderate correlations between the KOOS and unilateral measures of flexion peak torque (r = 0.514, P = .035) and flexion power (r = 0.54, P = .027). The middle group demonstrated the strongest correlations between the KOOS and symmetry measures of the single hop (r = 0.69, P = .002) and extension work (r = 0.71, P = .002) as well as unilateral measures of the triple hop (r = 0.52, P = .034) and extension work (r = 0.66, P = .004). The late group demonstrated strong correlations between the 6-m timed hop symmetry and the IKDC (r = 0.716, P = .001) and KOOS (r = 0.71, P = .001). CONCLUSION: Patients with a post-ACLR status of less than 2 years exhibited stronger relationships with unilateral strength measures to subjective function; graft type was found to change these relationships. Patients at 2 to 5 years postsurgery demonstrated relationships with both unilateral and symmetry measures of muscle function to subjective function. Patients who were more than 5 years after ACLR exhibited strong associations between hopping symmetry and subjective function. CLINICAL RELEVANCE: Future clinical guidelines for patients after ACLR may need to consider time since surgery as a potential factor.