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Background: After anterior cruciate ligament reconstruction (ACLR), asymmetry is likely to persist in single-leg (SL) vertical jump and drop jump performance than in SL hop distance. However, its relationship with the return to sport (RTS) remains unclear. Hypothesis/Purpose: This study aimed to determine the association between vertical jump performance after primary ACLR using hamstring tendon autograft and RTS at a pre-injury competitive level. Study design: Cross-sectional study Methods: Patients who underwent primary ACLR using hamstring tendon autograft were recruited for this study. Participants who returned to pre-injury competition after ACLR were recruited at least eight months postoperatively. Knee condition was assessed, including joint laxity, range of motion, muscle strength, and knee pain intensity during sports activities. Performance variables were also assessed, including SL hop distance, jump height in SL vertical jump, and reactive strength index (RSI; jump height/contact time) in SL drop jump. Participants were asked to subjectively report whether they had returned to the same level of competition as pre-injury and their perceived sport performance intensity. Those who answered "Yes" to the dichotomous question and had a postoperative subjective athletic performance of > 80% were categorized into the Yes-RTS group. The primary outcome was the ability to achieve RTS at the preinjury level. Results: Sixty-five patients (female, 35; male, 30) at 13.0 (13.0) [median (interquartile)] months after ACLR participated in this study. Thirty-nine (60%) were assigned to the Yes-RTS group. Regarding knee conditions, the No-RTS group had a significantly higher knee pain intensity, as assessed using a numerical rating scale (p<0.001, effect size -0.45). In the performance tests, the No-RTS group exhibited a significantly lower limb symmetry index of RSI during the SL drop jump compared to the Yes-RTS group (p=0.002, effect size 0.81). Conclusion: Patients unable to achieve RTS after primary ACLR using hamstring grafts are more likely to exhibit asymmetric performance during the SL drop jump test, suggesting the significance of assessing jump symmetry when evaluating post-ACLR rehabilitation success. Level of Evidence: 3c [ABSTRACT FROM AUTHOR]

This study aimed to determine differences in the hip abductor muscle activity during clam exercise at different hip flexion and femoral anteversion angles. Thirty healthy females were divided into two groups based on the femoral anteversion angle: the excessive femoral anteversion group and the normal group. Clam exercise was performed at three different hip flexion angles (60°, 45°, and 30°). Tensor fascia latae, gluteus medius, and superior portion of gluteus maximus activities were measured during the exercise, and the results were normalized to the activity during maximum voluntary isometric contraction to calculate the gluteal-to-tensor fascia latae muscle activation index. The superior portion of gluteus maximus activities at a hip flexion of 60° and 45° were greater than that at 30°. The excessive femoral anteversion group had a lower gluteal-to-tensor fascia latae muscle activation index than the normal group; the gluteal-to-tensor fascia latae muscle activation index for hip flexion at 60° was higher than that at 45°, and the gluteal-to-tensor fascia latae muscle activation index for hip flexion at 60° and 45° were higher than that at 30°. Therefore, the femoral anteversion angle and hip joint position were related to the activity of the hip abductor muscles during clam exercise. These findings may provide a rationale for instructing exercises to maximize the activity of the hip abductor muscles in individuals with an excessive femoral anteversion angle. [ABSTRACT FROM AUTHOR]

Context: Deficits in knee extension strength after anterior cruciate ligament reconstruction have been a major problem. The inadequate recovery of the knee extension strength of surgical limb reportedly delays return to sports and increases reinjury risk. Accordingly, the early detection of knee extension strength deficits after reconstruction may help plan early interventions to manage impairment. This study aimed to clarify the association between knee extension strength at 3 and 6 months after anterior cruciate ligament reconstruction. Design: Retrospective study. Methods: Fifty patients who underwent primary anterior cruciate ligament reconstruction using hamstring grafts were included. At 3 months postoperatively, the limb symmetry index (LSI) of isokinetic knee extension strength (IKE) at 60°/s, degree of swelling, passive range of motion of knee flexion and extension, and anterior leg reach distance were measured. At 6 months postoperatively, the LSI of IKE was measured at 60°/s, which was used as the main outcome. A correlation analysis was performed with the LSI of IKE at 6 months postoperatively as the dependent variable and the LSI of IKE at 3 months postoperatively as the independent variable. Subsequently, a multiple regression analysis was performed, with LSI of IKE at 6 months postoperatively as the dependent variable; LSI of IKE at 3 months postoperatively as the independent variable; and other variables, demographic information, and surgical data as covariates. Results: The correlation analysis revealed that the LSIs of IKE at 3 and 6 months postoperatively were correlated (r =.535, P <.001). In the multiple regression analysis, the LSI of IKE at 3 months postoperatively was significantly associated with that at 6 months postoperatively, even when other variables were included as covariates (R2 =.349, P =.004). Conclusion: Asymmetry of knee extension strength at 3 months postoperatively could be more useful than other variables related to knee strength in predicting the asymmetry of knee extension strength at 6 months postoperatively. [ABSTRACT FROM AUTHOR]

The lower-extremity kinematics associated with forward jump landing after an ankle injury is known to differ for patients with Chronic Ankle Instability (CAI), copers (injured but asymptomatic patients), and healthy individuals. However, the differences in the lower extremity kinematics of these groups associated with a Single-leg Lateral Drop Landing (SLDL) are unknown. The purpose of this study is to characterize the lower limb and foot kinematics during SLDL in CAI patients and to compare these characteristics with those of the copers and healthy individuals. This was a cross-sectional observational study. Nineteen participants, each, were selected from the CAI, Coper, and control groups. The lower-extremity kinematics during SLDL was measured using three-dimensional motion analysis over an interval progressing from 200 ms before landing to 200 ms after landing. Either one-way ANOVA or the Kruskal–Wallis test was used to compare the attributes of the respective groups, with each parameter measured every 10 ms. The maximum values and excursions of the parameters were established over time intervals progressing from 200 ms before landing to 200 ms after landing. Significant observations were subjected to post hoc analysis. Compared to the Coper group, the CAI group exhibited significantly smaller hip adduction angles at 160 ms, ankle dorsiflexion angles in the 110–150 ms interval, and maximum ankle dorsiflexion angles after landing. Compared to the control group, the CAI group exhibited significantly smaller excursions of MH inversion/eversion after landing. Our findings confirm the necessity of focusing on the kinematics of hip adduction/abduction and plantar/dorsiflexion during SLDL in evaluating patients with ankle injuries. [ABSTRACT FROM AUTHOR]

Introduction: Kinesiophobia is a fear of physical movement and activity and is known to affect return to sports and second injury after anterior cruciate ligament reconstruction. Objective: To determine the association among landing biomechanics, knee pain, and kinesiophobia in athletes following anterior cruciate ligament reconstruction. Design: A cross‐sectional study. Setting: Clinical center of sports medicine. Participants: This study included 31 athletes who participated in sports after primary, unilateral anterior cruciate ligament reconstruction (age, median [interquartile range]: 20.0 [7.0] years; body mass index: 22.2 [2.6] kg/m2; time from anterior cruciate ligament reconstruction: 24.0 [23.0] months). Interventions: Not applicable. Main Outcome Measures: Kinesiophobia was measured using the Tampa Scale for Kinesiophobia‐11. Knee function included joint laxity, strength, and single‐leg hop distance. Knee pain intensity during sports activities was measured using a numerical rating scale. Vertical ground reaction force was measured, and electromyography data for the vastus medialis and semitendinosus muscles during single‐leg jump landing were collected. Univariate correlation analysis and multiple regression analysis were performed to identify the associations between the Tampa Scale for Kinesiophobia‐11 score and outcome measures. Results: There was no correlation between peak vertical ground reaction force and Tampa Scale for Kinesiophobia‐11 score (Spearman's r = −0.17, p =.355). On multiple regression analyses, lower preparatory vastus medialis activity during landing (beta coefficient = −0.51, p <.001) and knee pain intensity (beta coefficient = 0.57, p <.001) were significantly associated with greater Tampa Scale for Kinesiophobia‐11 scores. Conclusions: In athletes who have participated in sports following anterior cruciate ligament reconstruction, lower preparatory vastus medialis activity during landing and knee pain intensity are associated with greater kinesiophobia. These findings indicate that interventions to address the landing muscle activity pattern and pain control should be performed to decrease kinesiophobia after anterior cruciate ligament reconstruction. [ABSTRACT FROM AUTHOR]

Recovery of the isokinetic knee extensor strength on the operated side following anterior cruciate ligament (ACL) reconstruction is commonly calculated as a ratio with the value from the non-operated side serving as the denominator. However, the validity of the values of the non-operated side remains unclear. This study aimed to determine the relationship between whole-body muscle mass and non-operated knee extensor strength after ACL reconstruction. In 27 patients who underwent ACL reconstruction, muscle mass was measured using bioelectrical impedance analysis, and bilateral concentric knee extensor strength was measured using an isokinetic dynamometer at angular velocities of 60∘/s and 180∘/s. Correlation and single regression analyses were performed to examine the relationship between whole-body muscle mass and knee extensor strength. There was a strong to very strong positive association between whole-body muscle mass and non-operated knee extensor strength (60∘/s: r= 0.85, 180∘/s: r= 0.90, P< 0.01). Univariate regression analysis showed that whole-body muscle mass was a strong predictor of non-operated knee extensor strength (R2= 0.71–0.81). Assessing both whole-body muscle mass and knee extensor strength may be used to determine whether muscle strength on the non-operated side is appropriate for the individual’s body composition. [ABSTRACT FROM AUTHOR]

Introduction: Kinesiophobia is a fear of physical movement and activity and is known to affect return to sports and second injury after anterior cruciate ligament reconstruction., Objective: To determine the association among landing biomechanics, knee pain, and kinesiophobia in athletes following anterior cruciate ligament reconstruction., Design: A cross-sectional study., Setting: Clinical center of sports medicine., Participants: This study included 31 athletes who participated in sports after primary, unilateral anterior cruciate ligament reconstruction (age, median [interquartile range]: 20.0 [7.0] years; body mass index: 22.2 [2.6] kg/m 2 ; time from anterior cruciate ligament reconstruction: 24.0 [23.0] months)., Interventions: Not applicable., Main Outcome Measures: Kinesiophobia was measured using the Tampa Scale for Kinesiophobia-11. Knee function included joint laxity, strength, and single-leg hop distance. Knee pain intensity during sports activities was measured using a numerical rating scale. Vertical ground reaction force was measured, and electromyography data for the vastus medialis and semitendinosus muscles during single-leg jump landing were collected. Univariate correlation analysis and multiple regression analysis were performed to identify the associations between the Tampa Scale for Kinesiophobia-11 score and outcome measures., Results: There was no correlation between peak vertical ground reaction force and Tampa Scale for Kinesiophobia-11 score (Spearman's r = -0.17, p = .355). On multiple regression analyses, lower preparatory vastus medialis activity during landing (beta coefficient = -0.51, p < .001) and knee pain intensity (beta coefficient = 0.57, p < .001) were significantly associated with greater Tampa Scale for Kinesiophobia-11 scores., Conclusions: In athletes who have participated in sports following anterior cruciate ligament reconstruction, lower preparatory vastus medialis activity during landing and knee pain intensity are associated with greater kinesiophobia. These findings indicate that interventions to address the landing muscle activity pattern and pain control should be performed to decrease kinesiophobia after anterior cruciate ligament reconstruction., (© 2022 American Academy of Physical Medicine and Rehabilitation.)

Context: Deficits in knee extension strength after anterior cruciate ligament reconstruction have been a major problem. The inadequate recovery of the knee extension strength of surgical limb reportedly delays return to sports and increases reinjury risk. Accordingly, the early detection of knee extension strength deficits after reconstruction may help plan early interventions to manage impairment. This study aimed to clarify the association between knee extension strength at 3 and 6 months after anterior cruciate ligament reconstruction., Design: Retrospective study., Methods: Fifty patients who underwent primary anterior cruciate ligament reconstruction using hamstring grafts were included. At 3 months postoperatively, the limb symmetry index (LSI) of isokinetic knee extension strength (IKE) at 60°/s, degree of swelling, passive range of motion of knee flexion and extension, and anterior leg reach distance were measured. At 6 months postoperatively, the LSI of IKE was measured at 60°/s, which was used as the main outcome. A correlation analysis was performed with the LSI of IKE at 6 months postoperatively as the dependent variable and the LSI of IKE at 3 months postoperatively as the independent variable. Subsequently, a multiple regression analysis was performed, with LSI of IKE at 6 months postoperatively as the dependent variable; LSI of IKE at 3 months postoperatively as the independent variable; and other variables, demographic information, and surgical data as covariates., Results: The correlation analysis revealed that the LSIs of IKE at 3 and 6 months postoperatively were correlated (r = .535, P < .001). In the multiple regression analysis, the LSI of IKE at 3 months postoperatively was significantly associated with that at 6 months postoperatively, even when other variables were included as covariates (R2 = .349, P = .004)., Conclusion: Asymmetry of knee extension strength at 3 months postoperatively could be more useful than other variables related to knee strength in predicting the asymmetry of knee extension strength at 6 months postoperatively.