Personalized volumetric assessment of lower body muscles in patients with knee injuries: A descriptive case series.

BACKGROUND: Patients with knee joint pathology present with variable muscular responses across the muscles of the lower limb and pelvis. Conventional approaches to characterizing muscle function are limited to gross strength assessments that may overlook subtle changes both in the thigh, hip and shank musculature. PURPOSE: To describe individualized patterns of lower extremity muscle volumes in patients with knee pathologies. METHODS: This was a retrospective case series performed in a University medical center. Nine patients diagnosed with meniscus tear recommended to undergo meniscectomy volunteered. Participants underwent 3.0 Tesla magnetic resonance imaging (MRI) of the lower extremities. Thirty-five MRI-derived muscle volumes were compared between limbs and expressed as percentage asymmetry. For additional context, z-scores were also calculated for mass- and height-normalized muscles and pre-determined muscle groupings relative to a normative database. RESULTS: There were no consistent patterns observed when considering between-limb asymmetries among all patients. The ankle musculature (dorsiflexors, plantar flexors, and invertors) was the only muscle group to be consistently smaller than normal for all patients, with the psoas major and flexor hallucis longus being the only individual muscles. The severity or chronicity of injury and presence of surgical intervention did not appear to have a clear effect on muscle volumes. CONCLUSION: Patients with a history of meniscal pathology demonstrate inconsistent patterns of lower extremity muscle volumes about the hip, knee, and ankle between limbs and in comparison to uninjured individuals. These data support the need for individualized assessment and intervention in this population.

Quantifying the relationship between quadriceps strength and aerobic fitness following anterior cruciate ligament reconstruction.

OBJECTIVE: To quantify the relationship between quadriceps strength and aerobic fitness following ACLR. METHODS: 42 individuals with ACLR (29F/13M, 20.2 ± 3.3years, 71.8 ± 17.4 kg, 171.1 ± 9.4 cm, 21.9 ± 21.5months post-surgery) and 38 healthy controls (24F/14M, 20.1 ± 1.4years, 69.8 ± 10.2 kg, 172.9 ± 8.7 cm) completed quadriceps strength testing using an instrumented dynamometer then completed an incremental treadmill test to determine aerobic fitness (VO2max). Bivariate Pearson's correlations were calculated between strength and VO2max. Significant correlations were retained for a regression analysis. RESULTS: Healthy controls demonstrated significantly greater VO2max compared to the ACLR group (d = 0.56). Unilateral strength variables were significantly correlated with VO2max (P ≤ 0.006) for both groups. Normalized peak isokinetic knee extensor torque was retained in the model, which explained 20.5% of the variance in healthy VO2max and 37.2% of the variance in ACLR VO2max. CONCLUSIONS: Aerobic fitness was reduced in the ACLR group in comparison to the healthy controls, despite unrestricted return to activity and similar activity levels between groups. Unilateral quadriceps strength was significantly correlated with aerobic fitness, which may be an indicator that greater unilateral strength may be a proxy for assessing aerobic fitness. Furthermore, sports medicine professionals may consider incorporating techniques and exercises during rehabilitation to improve cardiovascular fitness following ACLR.

Designing a screening battery for exercisers with Parkinson's disease.

PURPOSE: Develop a screening battery for persons with Parkinson's Disease (PD) that is easily administered in a short amount of time by community exercise professionals and measures changes in function. METHODS: An integrated, stakeholder-engaged, mixed methods approach included interviews and meetings with community exercise professionals on the development of a screening battery. Persons with PD (n = 57, age = 72.1 ± 8.1 years) who were already enrolled in fitness classes or individualized training at three locations participated in the screening battery twice over 8-16 weeks and provided feedback. Trends from interviews and meeting notes were identified using summative content analysis. Quantitative changes in performance were compared with paired t-tests. Cohen's d effect sizes were calculated for all significant differences. RESULTS: Current barriers for functional screenings included time and space. Using this feedback, we developed a screening battery that took under 20 min, required little equipment, had been previously validated, could be performed in individual and group settings, and provided objective feedback that was motivating for persons with PD to continue exercising. Persons with PD demonstrated improved functional performance on sit-to-stand (d = -0.71), two-minute walk test (d = -3.83), and arm curls (d = -0.78). CONCLUSION: Test results can be a motivator for persons with PD and lead to increased exercise adherence. Easily administered tests can show improvements in this population. Community exercise professionals are able to safely screen persons with PD to detect functional deficits and assist with programming.Implications for RehabilitationRegular exercise can slow declines in physical function and quality of life in people with Parkinson's disease.Use of physical assessments in community exercise programs can improve motivation to exercise for this population.Physical assessments such as sit-to-stand and arm curls can be used to demonstrate improvements in people with Parkinson's disease.

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 (

Post-traumatic osteoarthritis diagnosed within 5 years following ACL reconstruction.

PURPOSE: The purpose was to calculate the incidence of osteoarthritis in individuals following Anterior Cruciate Ligament Reconstruction (ACLR) in a large, national database and to examine the risk factors associated with OA development. METHODS: A commercially available insurance database was queried to identify new diagnoses of knee OA in patients with ACLR. The cumulative incidence of knee OA diagnoses in patients after ACLR was calculated and stratified by time from reconstruction. Odds ratios were calculated using logistic regression to describe factors associated with a new OA diagnosis including age, sex, BMI, meniscus involvement, osteochondral graft use, and tobacco use. RESULTS: A total of 10,565 patients with ACLR were identified that did not have an existing diagnosis of OA, 517 of which had a documented new diagnosis of knee OA 5 years after ACL reconstruction. When stratified by follow-up time points, the incidence of a new OA diagnosis within 6 months was 2.3%; within a 1-year follow-up was 4.1%; within 2 years, follow-up was 6.2%, within 3 years, follow-up was 8.4%; within 4 years, follow-up was 10.4%; and within 5 years, follow-up was 12.3%. Risk factors for new OA diagnoses were age (OR 2.44, P < 0.001), sex (OR 1.2, P = 0.002), obesity (OR 1.4, P < 0.001), tobacco use (OR = 1.3, P = 0.001), and meniscal involvement (OR 1.2, P = 0.005). CONCLUSION: Approximately 12% of patients presenting within 5 years following ACLR are diagnosed with OA. Demographic factors associated with an increased risk of a diagnosis of PTOA within 5 years after ACLR are age, sex, BMI, tobacco use, and concomitant meniscal surgery. Clinicians should be cognizant of these risk factors to develop risk profiles in patients with the common goal to achieve optimal long-term outcomes after ACLR. LEVEL OF EVIDENCE: III.

Sex Differences in Y-Balance Performance in Elite Figure Skaters.

Slater, LV, Vriner, M, Schuyten, K, Zapalo, P, and Hart, JM. Sex differences in Y-balance performance in elite figure skaters. J Strength Cond Res 34(5): 1416-1421, 2020-Asymmetrical dynamic balance compared with normative populations have been associated with increased risk of injury in athletes; however, it is unclear if the current data are similar to balance performance in figure skaters. Therefore, the purpose of this study was to compare performance on the Y-balance test between sexes and disciplines in elite figure skaters. Thirty-two senior level figure skaters from 3 different disciplines (singles, dance, and pairs) completed the Y-balance test on the take-off and landing leg. Absolute differences between limbs (cm), normalized differences between limbs (% leg length), and composite scores (CSs; % leg length) were calculated for all skaters. A multivariate analysis of variance was used to identify differences in performance based on discipline and sex. Females had a greater absolute difference between limbs (mean difference = -3.62 cm) and a greater normalized difference between limbs on the posterolateral (PL) reach compared with males (mean difference = -4.26% leg length). Ice dancers had larger CSs on the take-off leg compared with pair skaters (mean difference = 6.42%). These results suggest that male and female figure skaters demonstrate differences in dynamic balance in the PL direction, with female skaters exhibiting decreased reach on the landing leg, which may suggest asymmetrical hip strength in female figure skaters and increase risk of lower extremity injury in the landing leg. Sport performance professionals should consider these sex differences when designing strength programs for elite figure skaters.

Sex affects gait adaptations after exercise in individuals with anterior cruciate ligament reconstruction.

BACKGROUND: Osteoarthritis after anterior cruciate ligament reconstruction has been linked with changes in gait. Individuals with reconstruction demonstrate gait changes after exercise, however there is no information on altered gait after exercise based on sex. The purpose of this study was to examine the association of sex on changes in running gait after exercise in individuals with reconstruction compared to healthy. METHODS: Forty females (22 reconstructed) and 22 men (11 reconstructed) ran before and after exercise. Triplanar lower extremity kinematics and kinetics were measured on the involved limb. Data were reduced to 0-100% of gait. Change scores were calculated for each 1% with 90% confidence intervals. Mean differences were calculated for all significant differences. FINDINGS: After exercise, females with reconstruction increased knee valgus (1.81°), knee external rotation (2.02°), lateral trunk flexion (1.24°) and trunk rotation (2.15°) compared to healthy females. Females with reconstruction increased knee extension moment (0.07 Nm/kg), knee abduction moment (0.08 Nm/kg), hip extension moment (0.14 Nm/kg) and hip internal rotation moment (0.04 Nm/kg) compared to healthy females. After exercise, males with reconstruction decreased knee varus (-4.83°), hip adduction (-1.99°), and hip internal rotation (-4.44°), however increased lateral trunk flexion (1.94°) compared to healthy males. Males with reconstruction increased knee extension moment (0.07 Nm/kg), knee adduction moment (0.31 Nm/kg), knee internal rotation moment (0.13 Nm/kg), hip flexion moment (0.17 Nm/kg), and hip external rotation moment (0.05 Nm/kg) compared to healthy males. INTERPRETATION: Males with reconstruction increased hip loading while women with reconstruction increased trunk motion post-exercise. Sex should be considered when evaluating response to exercise after reconstruction.

Single-Leg Jump Performance Before and After Exercise in Healthy and Anterior Cruciate Ligament Reconstructed Individuals.

CONTEXT: Many clinicians measure lower-extremity symmetry after anterior cruciate ligament reconstruction (ACLR); however, testing is completed in a rested state rather than postexercise. Testing postexercise may better model conditions under which injury occurs. OBJECTIVE: To compare changes in single-leg performance in healthy and individuals with history of ACLR before and after exercise. DESIGN: Repeated-measures case-control. SETTING: Laboratory. PATIENTS: Fifty-two subjects (25 control and 27 ACLR). INTERVENTION: Thirty minutes of exercise. MAIN OUTCOME MEASURES: Limb symmetry and involved limb performance (nondominant for healthy) for single-leg hop, ground contact time, and jump height during the 4-jump test. Cohen d effect sizes were calculated for all differences identified using a repeated-measures analysis of variance. RESULTS: Healthy controls hopped farther than ACLR before (d = 0.65; confidence interval [CI], 0.09 to 1.20) and after exercise (d = 0.60; CI, 0.04 to 1.15). Those with ACLR had longer ground contact time on the reconstructed limb compared with the uninvolved limb after exercise (d = 0.53; CI, -0.02 to 1.09), and the reconstructed limb had greater ground contact time compared with the healthy control limb after exercise (d = 0.38; CI, -0.21 to 0.73). ACLR were less symmetrical than healthy before (d = 0.38; CI, 0.17 to 0.93) and after exercise (d = 0.84; CI, 0.28 to 1.41), and the reconstructed limb demonstrated decreased jump height compared with the healthy control limbs before (d = 0.75; CI, 0.19 to 1.31) and after exercise (d = 0.79; CI, 0.23 to 1.36). CONCLUSIONS: ACLR became more symmetric, which may be from adaptations of the reconstructed limb after exercise. Changes in performance and symmetry may provide additional information regarding adaptations to exercise after reconstruction.

Trends in Recurrent Anterior Cruciate Ligament Injuries Differ From New Anterior Cruciate Ligament Injuries in College and High School Sports: 2009-2010 Through 2016-2017.

BACKGROUND: Knee injuries are common and result in extended time missed from sports participation. Little is known regarding the comparative characteristics of recurrent versus first-time anterior cruciate ligament (ACL) injuries sustained during athletic events and how they are influenced by sex, sports participation level, and game-time features. PURPOSE: To evaluate the characteristics (sex, sports level, and game timing [ie, early vs late in the game]) of recurrent ACL injury in National Collegiate Athletic Association (NCAA) and high school athletes compared with first-time ACL injury. STUDY DESIGN: Descriptive epidemiology study. METHODS: Athletic trainers reported ACL injury occurrences and characteristics for collegiate athletes during the 2009-2010 through 2016-2017 academic years and for high school athletes during the 2011-2012 through 2013-2014 academic years. Logistic regression was used to estimate odds ratios (ORs) and 95% CIs for recurrent versus first-time ACL injury. The number of ACL injuries, proportions, and ORs were calculated by sex, competition level, and time in game played. Results were also classified according to injury mechanism: noncontact, overuse, or surface contact. RESULTS: A total of 705 ACL injuries were reported, including 644 first-time injures and 61 recurrent injuries. When restricting to noncontact ACL injuries, 416 were reported (373 first-time injuries and 43 recurrent injuries). The odds of a recurrent versus new ACL injury in NCAA student-athletes were 4.6 times that of high school student-athletes (95% CI, 1.41-15.24; P = .01). When restricting to noncontact ACL injuries, the odds of a recurrent versus new ACL injury during postseason and preseason were 4.5 and 2.8 times that during the regular season, respectively. Athletes in limited-contact and noncontact sports had greater odds of a recurrent versus new ACL injury compared with athletes playing football and other contact and collision sports. There was no significant difference in the odds of a recurrent ACL injury by sex or time in game. CONCLUSION: Based on the current study, the odds of recurrent ACL injuries are associated with the level of competition but not associated with sex or timing of game play. Determinants of reinjury after primary ACL reconstruction will help advance care for young injured athletes who continue to participate in competitive sports.

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.

Peak Lower Extremity Landing Kinematics in Dancers and Nondancers.

CONTEXT: Anterior cruciate ligament (ACL) injuries often occur during jump landings and can have detrimental short-term and long-term functional effects on quality of life. Despite frequently performing jump landings, dancers have lower incidence rates of ACL injury than other jump-landing athletes. Planned versus unplanned activities and footwear may explain differing ACL-injury rates among dancers and nondancers. Still, few researchers have compared landing biomechanics between dancers and nondancers. OBJECTIVE: To compare the landing biomechanics of dancers and nondancers during single-legged (SL) drop-vertical jumps. DESIGN: Cross-sectional study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 39 healthy participants, 12 female dancers (age = 20.9 ± 1.8 years, height = 166.4 ± 6.7 cm, mass = 63.2 ± 16.4 kg), 14 female nondancers (age = 20.2 ± 0.9 years, height = 168.9 ± 5.0 cm, mass = 61.6 ± 7.7 kg), and 13 male nondancers (age = 22.2 ± 2.7 years, height = 180.6 ± 9.7 cm, mass = 80.8 ± 13.2 kg). INTERVENTION(S): Participants performed SL-drop-vertical jumps from a 30-cm-high box in a randomized order in 2 activity (planned, unplanned) and 2 footwear (shod, barefoot) conditions while a 3-dimensional system recorded landing biomechanics. MAIN OUTCOME MEASURE(S): Overall peak sagittal-plane and frontal-plane ankle-, knee-, and hip-joint kinematics (joint angles) were compared across groups using separate multivariate analyses of variance followed by main-effects testing and pairwise-adjusted Bonferroni comparisons as appropriate ( P < .05). RESULTS: No 3-way interactions existed for sagittal-plane or frontal-plane ankle (Wilks λ = 0.85, P = .11 and Wilks λ = 0.96, P = .55, respectively), knee (Wilks λ = 1.00, P = .93 and Wilks λ = 0.94, P = .36, respectively), or hip (Wilks λ = 0.99, P = .88 and Wilks λ = 0.97, P = .62, respectively) kinematics. We observed no group × footwear interactions for sagittal-plane or frontal-plane ankle (Wilks λ = 0.94, P = .43 and Wilks λ = 0.96, P = .55, respectively), knee (Wilks λ = 0.97, P = .60 and Wilks λ = 0.97, P = .66, respectively), or hip (Wilks λ = 0.99, P = .91 and Wilks λ = 1.00, P = .93, respectively) kinematics, and no group × activity interactions were noted for ankle frontal-plane (Wilks λ = 0.92, P = .29) and sagittal- and frontal-plane knee (Wilks λ = 0.99, P = .81 and Wilks λ = 0.98, P = .77, respectively) and hip (Wilks λ = 0.88, P = .13 and Wilks λ = 0.85, P = .08, respectively) kinematics. A group × activity interaction (Wilks λ = 0.76, P = .02) was present for ankle sagittal-plane kinematics. Main-effects testing revealed different ankle frontal-plane angles across groups ( F2,28 = 3.78, P = .04), with male nondancers having greater ankle inversion than female nondancers ( P = .05). CONCLUSIONS: Irrespective of activity type or footwear, female nondancers landed with similar hip and knee kinematics but greater peak ankle eversion and less peak ankle dorsiflexion (ie, positions associated with greater ACL injury risk). Ankle kinematics may differ between groups due to different landing strategies and training used by dancers. Dancers' training should be examined to determine if it results in a reduced occurrence of biomechanics related to ACL injury during SL landing.

Activity monitoring in men's college soccer: a single season longitudinal study.

Performance in soccer has been characterized previously using time-motion analyses; however, it is unclear if men's college soccer shares performance characteristics with women's college or men's professional soccer. The purpose of this study was to compare proportions of matches spent walking, jogging, running, and sprinting in men's college soccer. Twenty-two male college soccer players wore global positioning system units during matches. Proportions of walking, jogging, running, high-speed running, and sprinting were calculated for each player based on time period (first half, second half, extra time) and outcome (win, loss, tie). Multivariate analyses of variance were run for each time period to compare positions. Means, 95% confidence intervals, and effect sizes were calculated for each position based on time period and match outcome. There were differences in low-speed and high-speed activities based on position, with forwards and midfielders demonstrating increased high-speed activities. Positional differences may require different physiological profiles and should be a consideration during training.

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.

Biomechanical adaptations during running differ based on type of exercise and fitness level.

Lower extremity injuries are most common in more active and fit individuals, suggesting that adaptations from neuromuscular fatigue may differ depending on type of exercise and fitness level. The purpose of this study was to compare changes in gait in highly fit and recreationally active individuals before and after two exercise protocols. Lower extremity kinematics and kinetics were measured on the dominant leg during running before and after two exercise protocols (walking/sport) from 0 to 100% of gait in 24 healthy individuals divided into higher (n=13) and lower fitness (n=11) groups. Change scores were calculated for each point of the gait cycle with 95% confidence intervals. There were no differences between groups in knee or hip kinematics and kinetics in response to the walking exercise protocol, however the higher fit group increased trunk extension and the lower fit group increased trunk lateral flexion after walking exercise. After the sport exercise, the higher fit group increased knee extension, knee valgus, trunk extension, knee flexion moment, knee varus moment, knee abduction moment, knee internal rotation moment, and hip flexion moment compared to the lower fit group. The lower fit group increased hip extension, hip abduction, hip internal rotation, trunk lateral flexion, trunk rotation, and knee external rotation moment compared the higher fit group after sport exercise. Greater between group differences were found with sport exercise compared to walking exercise. It is important to consider type of exercise and fitness level when assessing altered movement patterns in response to fatiguing exercise.

Progressive Changes in Walking Kinematics and Kinetics After Anterior Cruciate Ligament Injury and Reconstruction: A Review and Meta-Analysis.

CONTEXT: Anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) result in persistent alterations in lower extremity movement patterns. The progression of lower extremity biomechanics from the time of injury has not been described. OBJECTIVE: To compare the 3-dimensional (3D) lower extremity kinematics and kinetics of walking among individuals with ACL deficiency (ACLD), individuals with ACLR, and healthy control participants from 3 to 64 months after ACLR. DATA SOURCES: We searched PubMed and Web of Science from 1970 through 2013. STUDY SELECTION AND DATA EXTRACTION: We selected only articles that provided peak kinematic and kinetic values during walking in individuals with ACLD or ACLR and comparison with a healthy control group or the contralateral uninjured limb. DATA SYNTHESIS: A total of 27 of 511 identified studies were included. Weighted means, pooled standard deviations, and 95% confidence intervals were calculated for the healthy control, ACLD, and ACLR groups at each reported time since surgery. The magnitude of between-groups (ACLR versus ACLD, control, or contralateral limb) differences at each time point was evaluated using Cohen d effect sizes and associated 95% confidence intervals. Peak knee-flexion angle (Cohen d = -0.41) and external knee-extensor moment (Cohen d = -0.68) were smaller in the ACLD than in the healthy control group. Peak knee-flexion angle (Cohen d range = -0.78 to -1.23) and external knee-extensor moment (Cohen d range = -1.39 to -2.16) were smaller in the ACLR group from 10 to 40 months after ACLR. Reductions in external knee-adduction moment (Cohen d range = -0.50 to -1.23) were present from 9 to 42 months after ACLR. CONCLUSIONS: Reductions in peak knee-flexion angle, external knee-flexion moment, and external knee-adduction moment were present in the ACLD and ACLR groups. This movement profile during the loading phase of gait has been linked to knee-cartilage degeneration and may contribute to the development of osteoarthritis after ACLR.

A Comparison of Cervical Spine Motion After Immobilization With a Traditional Spine Board and Full-Body Vacuum-Mattress Splint.

BACKGROUND: The National Athletic Trainers' Association (NATA) advocates for cervical spine immobilization on a rigid board or vacuum splint and for removal of athletic equipment before transfer to an emergency medical facility. PURPOSE: To (1) compare triplanar cervical spine motion using motion capture between a traditional rigid spine board and a full-body vacuum splint in equipped and unequipped athletes, (2) assess cervical spine motion during the removal of a football helmet and shoulder pads, and (3) evaluate the effect of body mass on cervical spine motion. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty healthy male participants volunteered for this study to examine the influence of immobilization type and presence of equipment on triplanar angular cervical spine motion. Three-dimensional cervical spine kinematics was measured using an electromagnetic motion analysis system. Independent variables included testing condition (static lift and hold, 30° tilt, transfer, equipment removal), immobilization type (rigid, vacuum-mattress), and equipment (on, off). Peak sagittal-, frontal-, and transverse-plane angular motions were the primary outcome measures of interest. RESULTS: Subjective ratings of comfort and security did not differ between immobilization types (P > .05). Motion between the rigid board and vacuum splint did not differ by more than 2° under any testing condition, either with or without equipment. In removing equipment, the mean peak motion ranged from 12.5° to 14.0° for the rigid spine board and from 11.4° to 15.4° for the vacuum-mattress splint, and more transverse-plane motion occurred when using the vacuum-mattress splint compared with the rigid spine board (mean difference, 0.14 deg/s [95% CI, 0.05-0.23 deg/s]; P = .002). In patients weighing more than 250 lb, the rigid board provided less motion in the frontal plane (P = .027) and sagittal plane (P = .030) during the tilt condition and transfer condition, respectively. CONCLUSION: The current study confirms similar motion in the vacuum-mattress splint compared with the rigid backboard in varying sized equipped or nonequipped athletes. Cervical spine motion occurs when removing a football helmet and shoulder pads, at an unknown risk to the injured athlete. In athletes who weighed more than 250 lb, immobilization with the rigid board helped to reduce cervical spine motion. CLINICAL RELEVANCE: Athletic trainers and team physicians should consider immobilization of athletes who weigh more than 250 lb with a rigid board.

The Utility of Objective Strength and Functional Performance to Predict Subjective Outcomes After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Many clinicians release patients to return to activity after anterior cruciate ligament reconstruction (ACLR) based on time from surgery despite deficits in muscle strength and function. It is unclear whether symmetry or unilateral performance is the best predictor of subjective outcomes after ACLR. PURPOSE: To determine physical performance predictors of patient-reported outcomes after reconstruction. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 88 participants (49 males, 39 females; mean ± SD height, 174.0 ± 9.6 cm; weight, 76.1 ± 18.5 kg; age, 19.4 ± 3.7 years) who underwent primary, unilateral ACLR volunteered for this study. Participants had undergone reconstruction a mean of 6.9 ± 1.8 months (range, 5.0-14.1 months) before the study. All participants underwent strength testing as well as hop testing and then completed the International Knee Documentation Committee (IKDC) and Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaires. Stepwise linear regression models were used for symmetry and unilateral performance to identify the proportion of variance explained in the IKDC score, KOOS total score, KOOS-sport subscale, and time from surgery, as well as receiver operating characteristic (ROC) curve analyses on those variables that explained the most variance in patient-reported outcomes to determine cutoff thresholds. RESULTS: No significant correlations were found between time from surgery and objective performance. The only significant predictors of IKDC score were single-hop limb symmetry index (LSI) and age (R2 = 0.177) and unilateral triple-hop performance and age (R2 = 0.228). The cutoff for single-hop symmetry was 0.92 (area under the curve [AUC], 0.703; P = .012), and the cutoff for normalized triple-hop distance was 3.93 (AUC, 0.726; P = .005). When stratified by age, the cutoff for single-hop symmetry was 0.81 (AUC, 0.721; P = .051) for younger patients (age <19.1 years) and was not significant for older patients (age ≥19.1 years). The cutoff for normalized triple-hop distance was 3.85 (AUC, 0.832; P = .005) in older patients and was not significant for younger patients. The only significant predictors of KOOS-sport subscale were single-hop LSI (R2 = 0.140) and normalized knee extensor power at 180 deg/s (R2 = 0.096). When subjective outcomes were predicted based on KOOS-sport subscale, the cutoff for single-hop symmetry was 0.85 (AUC, 0.692; P = .018). CONCLUSION: Hopping performance is the most predictive functional variable of subjective outcomes after reconstruction. Single-hop symmetry was most important for younger patients and unilateral triple-hop distance was most important for older patients. Clinicians should consider hopping performance when making return-to-activity decisions after ACLR.

Muscle Activation Patterns During Different Squat Techniques.

Slater, LV, and Hart, JM. Muscle activation patterns during different squat techniques. J Strength Cond Res 31(3): 667-676, 2017-Bilateral squats are frequently used exercises in sport performance programs. Lower extremity muscle activation may change based on knee alignment during the performance of the exercise. The purpose of this study was to compare lower extremity muscle activation patterns during different squat techniques. Twenty-eight healthy, uninjured subjects (19 women, 9 men, 21.5 ± 3 years, 170 ± 8.4 cm, 65.7 ± 11.8 kg) volunteered. Electromyography (EMG) electrodes were placed on the vastus lateralis, vastus medialis, rectus femoris, biceps femoris, and the gastrocnemius of the dominant leg. Participants completed 5 squats while purposefully displacing the knee anteriorly (AP malaligned), 5 squats while purposefully displacing the knee medially (ML malaligned) and 5 squats with control alignment (control). Normalized EMG data (MVIC) were reduced to 100 points and represented as percentage of squat cycle with 50% representing peak knee flexion and 0 and 99% representing fully extended. Vastus lateralis, medialis, and rectus femoris activity decreased in the medio-lateral (ML) malaligned squat compared with the control squat. In the antero-posterior (AP) malaligned squat, the vastus lateralis, medialis, and rectus femoris activity decreased during initial descent and final ascent; however, vastus lateralis and rectus femoris activation increased during initial ascent compared with the control squat. The biceps femoris and gastrocnemius displayed increased activation during both malaligned squats compared with the control squat. In conclusion, participants had altered muscle activation patterns during squats with intentional frontal and sagittal malalignment as demonstrated by changes in quadriceps, biceps femoris, and gastrocnemius activation during the squat cycle.