The effect of factors from different time points on psychological readiness following ACL reconstruction.

OBJECTIVE: The purpose of this study was to examine factors correlated with psychological readiness to return to activity after ACLR. DESIGN: cross sectional study. SETTING: controlled laboratory. PARTICIPANTS: 164 patients (82 M/82 F, 22.5 ± 8.9yr, 171.6 ± 11.0 cm, 77.4 ± 18.6 kg, 8.6 ± 3.4 months post-ACLR) participated in this study after a primary, isolated, and uncomplicated ACLR. MAIN OUTCOME MEASURES: ACL Return to Sport Index (ACL-RSI). RESULTS: ACL-RSI scores demonstrated a weak positive correlation with activity level at the time of injury and a fair positive correlation with activity level at the time of post-operative testing (p-values: 0.004, <0.001). ACL-RSI scores showed a statistically significant fair negative correlation with pain and a moderate negative correlation with kinesiophobia during rehabilitation (p-values: <0.001, <0.001). There was no statistical significance between ACL-RSI and the surgical variables (p-value range: 0.10-0.61). CONCLUSIONS: Outcomes from testing during postoperative rehabilitation were most correlated with psychological readiness to return to activity after ACLR. Increased pain and kinesiophobia were associated with a decreased psychological readiness. Increased activity level prior to injury and activity level at the time of testing during rehabilitation were both correlated with increased psychological readiness. Psychological readiness to return to activity may need to be customized based on potentially modifiable patient-specific factors during the post-operative rehabilitation.

Associations Between Race & Socioeconomic Status, Lower Extremity Strength, and Patient Reported Outcomes Following Anterior Cruciate Ligament Reconstruction.

CONTEXT: There are significant disparities in access to health care, but there are limited data about the impact of race and socioeconomic status (SES) on postoperative outcomes following anterior cruciate ligament (ACL) reconstruction (ACLR) surgery. OBJECTIVE: To identify associations between area deprivation index (ADI), strength measures and patient-reported outcomes (PROs) following ACLR as well as to examine differences in outcomes between race, sex, and race. DESIGN: Case control study in a single hospital setting. SETTING: Database secondary analysis. PATIENTS OR OTHER PARTICIPANTS: Data was collected from 340 patients who underwent primary, isolated, unilateral ACLR. MAIN OUTCOME MEASURES: Strength measures and PROs were obtained at patients' postoperative assessments at approximately six months post-surgery. Area Deprivation Index values were calculated on each patient's census tract, determined through medical records review. Correlations were conducted to determine the relationship between ADI and KOOS measures, IKDC, and limb symmetry on strength measurements. The racial composition of the sample was heavily skewed and was excluded from statistical analyses. RESULTS: ADI was weakly correlated with IKDC (ρ=0.11, p=0.04) outcomes, with more disadvantaged patients reporting better quality of life and knee function. ADI was not correlated with other outcomes of interest. The median ADI value of the sample was 32 (range 1-86 [IQR 19-47]). CONCLUSIONS: Our study revealed a weak correlation between higher levels of socioeconomic disadvantage as measured by ADI and improved subjective assessment of knee function and quality of life as measured by IKDC. These findings are contrary to what other studies on this subject have found and highlight the importance of further research into the impact of SES and other social determinants of health on post ACLR outcomes.

Transference of outdoor gait-training to treadmill running biomechanics and strength measures: A randomized controlled trial.

Outdoor gait-training has been successful in improving pain and reducing contact time during outdoor running for runners with exercise-related lower leg pain (ERLLP). However, it is unclear if these adaptations translate to gold standard treadmill running and clinical strength assessments. The study purpose was to assess the influence of a 4-week outdoor gait-training intervention with home exercises (FBHE) on treadmill running biomechanics and lower extremity strength compared to home exercises alone (HE) among runners with ERLLP. Seventeen runners with ERLLP were randomly allocated to FBHE and HE groups (FBHE: 3 M, 6F, 23 ± 4 years, 22.0 ± 4.6 kg/m2; HE: 3 M, 5F, 25 ± 5 years, 24.0 ± 4.0 kg/m2). Both groups completed eight sessions of home exercises over 4 weeks. The FBHE group received gait-training through wearable sensors to reduce contact time. Treadmill running gait and clinical strength assessments were conducted at baseline and 4-weeks. Multivariate repeated measures analyses of variance were used to assess the influence of group and timepoint for all outcomes. The FBHE group demonstrated significantly decreased contact time at 4-weeks compared to baseline and the HE group (Mean Difference [MD] range: -42 ms - -39 ms; p-range: <0.001-0.02). The FBHE group had significantly increased cadence (MD: +21 steps/min; p = 0.003) and decreased loading impulse (MD: -51, p < 0.001) during treadmill running at 4-weeks compared to the HE group. Strength did not significantly differ adjusting for multiple comparisons (p > 0.007). The outdoor FBHE intervention transferred to favorable changes in treadmill running biomechanics. Clinicians treating runners with ERLLP patients should implement data-driven outdoor gait-training to maximize patient benefits across running locations.

Knee extensor torque-velocity relationships following anterior cruciate ligament reconstruction.

BACKGROUND: The inherent nature of the torque-velocity relationship is the inverse nature between the velocity of muscle contraction and torque production and is an indication of muscle function. The purpose of this study was to characterize the torque-velocity relationship in the quadriceps following anterior cruciate ligament reconstruction compared to healthy limbs. METHODS: 681 participants were included, 493 of which were patients at least four months following anterior cruciate ligament reconstruction (23.2 ± 10.08 yr, 6.6 ± 5.37 months post-surgery) and 188 were healthy participants (21.6 ± 3.77 yr). A subset of 175 post-surgical participants completed a repeated visit (8.1 ± 1.71 months post-surgery). Participants completed isokinetic knee extension at 90°/s and 180°/s. A one-way ANOVA was used to compare torque velocity relationships by limb type (surgical, contralateral, healthy). Paired samples t-tests were conducted to analyze the torque-velocity relationship across limbs and across time. FINDINGS: There was a large effect for limb type on torque-velocity (F(2, 1173) = 146.08, p < 0.001, η2 = 0.20). Surgical limbs demonstrated significantly lower torque-velocity relationships compared to the contralateral limbs (ACLR: 0.26 Nm/kg, contralateral:0.55 Nm/kg, p < 0.001, d = 1.18). Healthy limbs had similar torque-velocity relationships bilaterally (dominant limb: 0.48 Nm/kg, non-dominant limb: 0.49 Nm/kg, p = 0.45). The torque velocity relationship for the involved limb significantly increased in magnitude over time (+0.11 Nm/kg, p < 0.001, d = -0.61) while the contralateral limb torque-velocity relationship remained stable over time (0.0 Nm/kg difference, p = 0.60). INTERPRETATION: Following surgery, the knee extensors appear to have altered torque-velocity relationships compared to contralateral and healthy limbs. This may indicate a specific target for assessment and rehabilitation following surgery.

Hip Strength Recovery After Anterior Cruciate Ligament Reconstruction.

Background: Return-to-play (RTP) assessment after anterior cruciate ligament reconstruction (ACLR) rarely includes hip strength. Hypothesis: It was hypothesized that (1) patients after ACLR will have weaker hip abduction (AB) and adduction (AD) strength compared with the contralateral limb, with larger deficits in women, (2) there will be a correlation between hip and thigh strength ratios and patient-reported outcomes (PROs), and (3) hip AB and AD strength will improve over time. Study Design: Descriptive laboratory study. Methods: Included were 140 patients (74 male, 66 female; mean age, 24.16 ± 10.82 years) who underwent RTP assessment at 6.1 ± 1.6 months after ACLR; 86 patients underwent a second assessment at 8.2 ± 2.2 months. Hip AB/AD and knee extension/flexion isometric strength were measured and normalized to body mass, and PRO scores were collected. Strength ratios (hip vs thigh), limb differences (injured vs uninjured), sex-based differences, and relationships between strength ratios and PROs were determined. Results: Hip AB strength was weaker on the ACLR limb (ACLR vs contralateral: 1.85 ± 0.49 vs 1.89 ± 0.48 N·m/kg; P < .001) and hip AD torque was stronger (ACLR vs contralateral: 1.80 ± 0.51 vs 1.76 ± 0.52 N·m/kg; P = .004), with no sex-by-limb interaction found. Lower hip-to-thigh strength ratios of the ACLR limb were correlated with higher PRO scores (r = -0.17 to -0.25). Over time, hip AB strength increased in the ACLR limb more than in the contralateral limb (P = .01); however, the ACLR limb remained weaker in hip AB at visit 2 (ACLR vs contralateral: 1.88 ± 0.46 vs 1.91 ± 0.45 N·m/kg; P = .04). In both limbs, hip AD strength was greater at visit 2 than visit 1 (ACLR: 1.82 ± 0.48 vs 1.70 ± 0.48 N·m/kg; contralateral: 1.76 ± 0.47 vs 1.67 ± 0.47 N·m/kg; P < .01 for both). Conclusion: The ACLR limb had weaker hip AB and stronger AD compared with the contralateral limb at initial assessment. Hip muscle strength recovery was not influenced by sex. Hip strength and symmetry improved over the course of rehabilitation. Although strength differences across limbs were minor, the clinical importance of these differences is still unknown. Clinical Relevance: The evidence provided highlights the need to integrate hip strength into RTP assessments to identify hip strength deficits that may increase reinjury or lead to poor long-term outcomes.

Comparison of Patient-Reported Outcomes, Strength, and Functional Performance in Primary Versus Revision Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Clinical outcomes after revision anterior cruciate ligament reconstruction (ACLR) are not well understood. HYPOTHESIS: Patients undergoing revision ACLR would demonstrate worse patient-reported outcomes and worse limb symmetry compared with a cohort undergoing primary ACLR. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: 672 participants (373 with primary ACLR, 111 with revision ACLR, and 188 uninjured) completed functional testing at a single academic medical center. Descriptive information, operative variables, and patient-reported outcomes (International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, and Tegner Activity Scale score) were assessed for each patient. Quadriceps and hamstring strength tests were conducted using a Biodex System 3 Dynamometer. Single-leg hop for distance, triple hop test, and the 6-m timed hop test were also assessed. Limb symmetry index (LSI) between the ACLR limb and contralateral limb was calculated for strength and hop testing. Normalized peak torque (N·m/kg) was calculated for strength testing. RESULTS: No differences were found in group characteristics, excluding body mass (P < .001), or in patient-reported outcomes. There were no interactions between revision status, graft type, and sex. Knee extension LSI was inferior (P < .001) in participants who had undergone primary (73.0% ± 15.0%) and revision (77.2% ± 19.1%) ACLR compared with healthy, uninjured participants (98.8% ± 10.4%). Knee flexion LSI was inferior (P = .04) in the primary group (97.4% ± 18.4%) compared with the revision group (101.9% ± 18.5%). Difference in knee flexion LSI between the uninjured and primary groups, as well as between the uninjured and revision groups, did not reach statistical significance. Hop LSI outcomes were significantly different across all groups (P < .001). Between-group differences in extension in the involved limb (P < .001) were noted, as the uninjured group exhibited stronger knee extension (2.16 ± 0.46 N·m/kg) than the primary group (1.67 ± 0.47 N·m/kg) and the revision group (1.78 ± 0.48 N·m/kg). As well, differences in flexion in the involved limb (P = .01) were found, as the revision group exhibited stronger knee flexion (1.06 ± 0.25 N·m/kg) than the primary group (0.97 ± 0.29 N·m/kg) and the uninjured group (0.98 ± 0.24 N·m/kg). CONCLUSION: At 7 months postoperatively, patients who had undergone revision ACLR did not demonstrate inferior patient-reported outcomes, limb symmetry, strength, or functional performance compared with patients who had undergone primary ACLR. Patients who had undergone revision ACLR exhibited greater strength and LSI than their counterparts with primary ACLR, but these parameters were still inferior to those of uninjured controls.

Microglial activation persists beyond clinical recovery following sport concussion in collegiate athletes.

Introduction: In concussion, clinical and physiological recovery are increasingly recognized as diverging definitions. This study investigated whether central microglial activation persisted in participants with concussion after receiving an unrestricted return-to-play (uRTP) designation using [18F]DPA-714 PET, an in vivo marker of microglia activation. Methods: Eight (5 M, 3 F) current athletes with concussion (Group 1) and 10 (5 M, 5 F) healthy collegiate students (Group 2) were enrolled. Group 1 completed a pre-injury (Visit1) screen, follow-up Visit2 within 24 h of a concussion diagnosis, and Visit3 at the time of uRTP. Healthy participants only completed assessments at Visit2 and Visit3. At Visit2, all participants completed a multidimensional battery of tests followed by a blood draw to determine genotype and study inclusion. At Visit3, participants completed a clinical battery of tests, brain MRI, and brain PET; no imaging tests were performed outside of Visit3. Results: For Group 1, significant differences were observed between Visits 1 and 2 (p < 0.05) in ImPACT, SCAT5 and SOT performance, but not between Visit1 and Visit3 for standard clinical measures (all p > 0.05), reflecting clinical recovery. Despite achieving clinical recovery, PET imaging at Visit3 revealed consistently higher [18F]DPA-714 tracer distribution volume (VT) of Group 1 compared to Group 2 in 10 brain regions (p < 0.001) analyzed from 164 regions of the whole brain, most notably within the limbic system, dorsal striatum, and medial temporal lobe. No notable differences were observed between clinical measures and VT between Group 1 and Group 2 at Visit3. Discussion: Our study is the first to demonstrate persisting microglial activation in active collegiate athletes who were diagnosed with a sport concussion and cleared for uRTP based on a clinical recovery.

Kinesiophobia Is Related to Acute Musculoskeletal Injury Incidence Following Concussion.

CONTEXT: Athletes with a history of sport concussion (SC) have an increased risk of musculoskeletal injury (MSK); however, the underlying mechanisms have yet to be determined. The purpose of our study was to evaluate kinesiophobia in college athletes with or without a time-loss MSK within 180 days of unrestricted return to play following a SC. DESIGN: This was a retrospective cohort study within a sports medicine facility. METHODS: Participants were eligible if they were diagnosed with a SC, completed the Tampa Scale of Kinesiophobia (TSK), and completed an unrestricted return to play. Fifty-six college athletes (40 men and 16 women) with an average age of 19.5 (1.25) years, height of 183.5 (10.45) cm, and mass of 94.72 (24.65) kg, were included in the study. MSK participants were matched to non-MSK participants 1:1. Demographic and TSK outcome scores were compared using independent t tests. The proportion of participants in each group who scored above the clinical threshold (TSK ≥ 37) was compared using a chi-square analysis. Alpha was set at α = .05. RESULTS: The MSK group (31.2 [6.30]) reported similar TSK scores to the matched group (28.9 [3.34]; t54 = 1.70, P = .10, d = 0.45 [-0.08 to 0.97]). A greater proportion of athletes who were diagnosed with an MSK-reported scores above the cutoff (χ2[1] = 6.49, P = .01). CONCLUSIONS: Athletes diagnosed with SC had similar kinesiophobia values regardless of MSK status. However, a higher proportion of athletes with a time-loss MSK injury reported a TSK score greater than the clinical cutoff. Our results suggest that factors such as kinesiophobia should be considered following a SC.

Sensor-based gait training to reduce contact time for runners with exercise-related lower leg pain: a randomised controlled trial.

Objectives: To assess the effects of a 4-week randomised controlled trial comparing an outdoor gait-training programme to reduce contact time in conjunction with home exercises (contact time gait-training feedback with home exercises (FBHE)) to home exercises (HEs) alone for runners with exercise-related lower leg pain on sensor-derived biomechanics and patient-reported outcomes. Design: Randomised controlled trial. Setting: Laboratory and field-based study. Participants: 20 runners with exercise-related lower leg pain were randomly allocated into FBHE (4 male (M), 6 female (F), 23±4 years, 22.0±4.3 kg/m2) or HE groups (3 M, 7 F, 25±5 years, 23.6±3.9 kg/m2). Interventions: Both groups completed eight sessions of HEs over 4 weeks. The FBHE group received vibrotactile feedback through wearable sensors to reduce contact time during outdoor running. Primary and secondary outcome measures: Patient-reported outcome measures (PROMs) and outdoor gait assessments were conducted for both groups at baseline and 4 weeks. PROMs were repeated at 6 weeks, and feedback retention was assessed at 6 weeks for the FBHE group. Repeated measures analyses of variance were used to assess the influence of group and timepoint on primary outcomes. Results: The FBHE group reported increased function and recovery on PROMs beyond the HE group at 6 weeks (p<0.001). There was a significant group by time interaction for Global Rating of Change (p=0.004) and contact time (p=0.002); the FBHE group reported greater subjective improvement and reduced contact time at 4 and 6 weeks compared with the HE group and compared with baseline. The FBHE group had increased cadence (mean difference: 7 steps/min, p=0.01) at 4 weeks during outdoor running compared with baseline. Conclusion: FBHE was more effective than HE alone for runners with exercise-related lower leg pain, manifested with improved PROMs, reduced contact time and increased cadence. Trial registration number: NCT04270565.

Disagreement in Pass Rates Between Strength and Performance Tests in Patients Recovering From Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Performance on strength and functional tests is often used to guide postoperative rehabilitation progress and return to activity decisions after anterior cruciate ligament reconstruction (ACLR). Clinicians may have difficulty in determining which criteria to follow if there is disagreement in performance outcomes among the tests. PURPOSE/HYPOTHESIS: The purpose of this study was to compare pass rates between strength tests and single-leg hop (SLHOP) tests among men and women and between patients with lower and higher preinjury activity levels recovering from ACLR. We hypothesized that pass rates would be nonuniformly distributed among test types, sex, and activity level and that more participants would pass hop tests than strength tests. DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 299 participants (146 men; 153 women)-at a mean of 6.8 ± 1.4 months after primary, unilateral, and uncomplicated ACLR (mean age, 23 ± 9.7 years; mean height, 172 ± 10.5 cm; mean mass, 75.8 ± 18.4 kg)-completed testing. Quadri.tif strength was evaluated using peak torque during isokinetic knee extension at 90 deg/s and 180 deg/s. Jump distance during the SLHOP and triple hop tests was measured (in cm). Strength and hop test measures were evaluated based on the limb symmetry index ((LSI) = (ACLR / contralateral side) × 100). We operationally defined "pass" as >90% on the LSI. RESULTS: Pass rates were nonuniformly distributed between isokinetic knee extension at 90 deg/s and the SLHOP test (χ2 = 18.64; P < .001). Disagreements between isokinetic testing at 90 deg/s and the SLHOP test occurred in 36.5% (109/299) of the participants. Among those who failed strength testing and passed hop testing, a greater portion reported higher activity levels before their injury (χ2 = 6.90; P = .01); however, there was no difference in pass rates between men and women. Similar patterns of disagreement were observed between all strength test and hop test outcomes. CONCLUSION: ACLR patients with higher activity levels may be more likely to pass hop testing despite failing quadri.tif strength testing. This may be an indicator of movement compensations to achieve jump symmetry in the presence of quadri.tif weakness.

Reevaluating clinical assessment outcomes after unrestricted return to play following sport-related concussion.

PRIMARY OBJECTIVE: The objective of this study was to examine neurocognition, postural control, and symptomology at multiple timepoints following concussion. We hypothesized that collegiate athletes would perform similar to or better than their baseline in terms of each outcome at both timepoints. RESEARCH DESIGN: This was a retrospective study of 71 collegiate athletes (18.3 ± 0.89 years old; 182.2 ± 10.05 cm; 84.2 ± 20.07 kg) to observe changes in outcomes from a previously established clinical protocol. METHODS AND PROCEDURES: Participants were administered ImPACT™, the Sensory Organization Test (SOT), and the revised head injury scale (HIS-r) prior to their seasons (baseline); upon reporting symptom-free following concussion (post-injury); and approximately 8-months after return-to-play to establish a new baseline. MAIN OUTCOMES AND RESULTS: There were no changes in ImPACT scores or HIS-r reporting over time. ImPACT total symptom score (TSS) decreased over time (p = .002, ηp2 = 0.08). Significant main effects occurred for the SOT equilibrium score (p < .01, ηp2 = 0.34) and Vestibular sensory ratio (p < .001, ηp2 = 0.22). CONCLUSIONS: Our data suggest no decline in neurocognition, balance, or symptom burden approximately eight months post-injury. As clinicians continue to explore "best practices" for concussion management and potential long-term implications of these injuries it is important to monitor outcome measures longitudinally.