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Individuals with anterior cruciate ligament reconstruction (ACLR) often fail to return to their previous level of sport performance. Although multifaceted, this inability to regain preinjury performance may be influenced by impaired plyometric ability attributable to chronic quadriceps dysfunction. Whole-body vibration (WBV) acutely improves quadriceps function and biomechanics after ACLR, but its effects on jumping performance outcomes such as jump height, the reactive strength index (RSI), and knee work and power are unknown. To evaluate the acute effects of WBV on measures of jumping performance in those with ACLR. Crossover study design. Research laboratory. Thirty-six individuals with primary, unilateral ACLR. Participants stood on a WBV platform in a mini-squat position while vibration or no vibration (control) was applied during six 60-second bouts with 2 minutes of rest between bouts. Double-leg jumping tasks were completed preintervention and postintervention (WBV or control) and consisted of jumping off a 30-cm box to 2 force plates half the participant's height away. The jumping task required participants to maximally jump vertically upon striking the force plates. Whole-body vibration did not produce significant improvements in any of the study outcomes (ie, jump height, RSI, and knee work and power) in either limb (P =.053–.839). These results suggest that a single bout of WBV is insufficient for improving jumping performance in individuals with ACLR. As such, using WBV to acutely improve jumping performance post-ACLR is likely not warranted. Future research should evaluate the effects of repeated exposure to WBV in combination with other plyometric interventions on jumping performance. [ABSTRACT FROM AUTHOR]

Background Muscular strength deficits are common after ACL injury. While the Limb Symmetry Index (LSI), using the uninvolved limb as a reference, is widely used, negative strength adaptations may affect both limbs post-injury. It is uncertain how the strength of the uninvolved limb in those with an ACL injury compares to uninjured individuals, making it unclear whether it is appropriate as a benchmark for determining sufficient strength. Purpose To compare the strength of key lower extremity muscles of the uninvolved limb in those with history of ACL injury (ACL-I) to the dominant limb in individuals with no history of ACL injury (control). Study Design Cross-sectional study. Methods: A total of 5,727 military cadets were examined, with 82 females and 126 males in the ACL-I group and 2,146 females and 3,373 males in the control group. Maximum isometric strength was assessed for six muscle groups measured with a hand-held dynamometer. Separate two-way ANOVAs with limb and sex were performed for each muscle group. Results Significant main effects for limb were observed with the uninvolved limb in the ACL-I group displaying greater strength compared to the dominant limb in the control group for the quadriceps, hamstrings, and gluteus medius, but effect sizes were small (Cohen's d <0.25). Significant main effects for sex were observed with greater male muscular strength in all six muscle groups with small to large effect sizes (Cohen's d 0.49-1.46). No limb-by-sex interactions were observed. Conclusions There was no evidence of reduced strength in the uninvolved limb in those with a history of ACL injury compared to the dominant limb in those with no prior ACL injury. This finding suggests that, after clearance to return to activities, the uninvolved limb can be used as a standard for comparison of sufficient strength, including when using the LSI. Level of Evidence: Level 3 [ABSTRACT FROM AUTHOR]

Objective: The association between knee injury and knee osteoarthritis (OA) is understudied relative to its importance, particularly in younger populations. This study was undertaken to examine the association of knee injury with radiographic features of knee OA in military officers, who have a physically demanding profession and high rates of knee injury. Methods: Participants were recruited in 2015–2017 from an existing program that enrolled 6,452 military officers during 2004–2009. Officers with a history of knee ligament or meniscal injuries (n = 117 via medical record review) were compared to officers with no history of knee injury (n = 143). Bilateral posteroanterior knee radiographs were obtained using a standardized fixed‐flexion positioning frame. All images were read for Kellgren/Lawrence (K/L) grade, osteophyte (OST), and joint space narrowing (JSN) scores. Data were analyzed using linear‐risk regression models with generalized estimating equations. Results: Injured and noninjured participants were similar (mean age 28 years, mean body mass index 25 kg/m2, ~40% female). The mean time from first knee injury to imaging among injured participants was 9.2 years. Compared with noninjured knees, greater prevalence of radiographic OA (K/L grade ≥ 2), OST (grade ≥ 1), and JSN (grade ≥ 1) was observed among injured knees, with prevalence differences of +16% (95% confidence interval [95% CI] 10%, 22%), +29% (95% CI 20%, 38%), and + 17% (95% CI 10%, 24%), respectively. Approximately 1 in 6 officers with prior knee injury progressed to radiographic OA by age 30 years. Conclusion: At the midpoint of a projected 20‐year military career, officers with a history of traumatic knee injury have a markedly increased prevalence of knee radiographic OA compared to officers without injury. [ABSTRACT FROM AUTHOR]

The Osteoarthritis Action Alliance formed a secondary prevention task group to develop a consensus on secondary prevention recommendations to reduce the risk of osteoarthritis after a knee injury. Our goal was to provide clinicians with secondary prevention recommendations that are intended to reduce the risk of osteoarthritis after a person has sustained an anterior cruciate ligament injury. Specifically, this manuscript describes our methods, literature reviews, and dissenting opinions to elaborate on the rationale for our recommendations and to identify critical gaps. Consensus process. Virtual video conference calls and online voting. The Secondary Prevention Task Group consisted of 29 members from various clinical backgrounds. The group initially convened online in August 2020 to discuss the target population, goals, and key topics. After a second call, the task group divided into 9 subgroups to draft the recommendations and supportive text for crucial content areas. Twenty-one members completed 2 rounds of voting and revising the recommendations and supportive text between February and April 2021. A virtual meeting was held to review the wording of the recommendations and obtain final votes. We defined consensus as >80% of voting members supporting a proposed recommendation. The group achieved consensus on 15 of 16 recommendations. The recommendations address patient education, exercise and rehabilitation, psychological skills training, graded-exposure therapy, cognitive-behavioral counseling (lacked consensus), outcomes to monitor, secondary injury prevention, system-level social support, leveraging technology, and coordinated care models. This consensus statement reflects information synthesized from an interdisciplinary group of experts based on the best available evidence from the literature or personal experience. We hope this document raises awareness among clinicians and researchers to take steps to mitigate the risk of osteoarthritis after an anterior cruciate ligament injury. [ABSTRACT FROM AUTHOR]

Those with chronic ankle instability (CAI) demonstrate deleterious changes in talar cartilage composition, resulting in alterations of talar cartilage loading behavior. Common impairments associated with CAI may play a role in cartilage behavior in response to mechanical loading. To identify mechanical and sensorimotor outcomes that are linked with the magnitude of talar cartilage deformation after a static loading protocol in patients with and those without CAI. Cross-sectional study. Laboratory setting. Thirty individuals with CAI and 30 healthy individuals. After a 60-minute off-loading period, ultrasonographic images of the talar cartilage were acquired immediately before and after a 2-minute static loading protocol (single-legged stance). Talar cartilage images were obtained and manually segmented to enable calculation of medial, lateral, and overall average talar thickness. The percentage change, relative to the average baseline thickness, was used for further analysis. Mechanical (ankle joint laxity) and sensorimotor (static balance and Star Excursion Balance Test) outcomes were captured. Partial correlations were computed to determine associations between cartilage deformation magnitude and the mechanical and sensorimotor outcomes after accounting for body weight. In the CAI group, greater inversion laxity was associated with greater overall (r = −0.42, P =.03) and medial (r = −0.48, P =.01) talar cartilage deformation after a 2-minute static loading protocol. Similarly, poorer medial-lateral static balance was linked with greater overall (r = 0.47, P =.01) and lateral (r = 0.50, P =.01) talar cartilage deformation. In the control group, shorter posterolateral Star Excursion Balance Test reach distance was associated with greater lateral cartilage deformation (r = 0.42, P =.03). No other significant associations were observed. In those with CAI, inversion laxity and poor static postural control were moderately associated with greater talar cartilage deformation after a 2-minute static loading protocol. These results suggest that targeting mechanical instability and poor balance in those with CAI via intervention strategies may improve how the talar cartilage responds to static loading conditions. [ABSTRACT FROM AUTHOR]

Researchers have not established if overloading or underloading movement profiles are present in symptomatic and asymptomatic athletes with patellar tendon structural abnormality (PTA) compared with healthy athletes. To compare involved-limb landing biomechanics between male athletes with and those without patellar tendinopathy. Cross-sectional study. Laboratory. A total of 43 male athletes were grouped based on patellar tendon pain and ultrasound imaging of the proximal patellar tendon: symptomatic with PTA (SYM; n = 13; age = 19.62 ± 1.61 years, height = 1.82 ± 0.05 m, mass = 83.46 ± 5.12 kg), asymptomatic with PTA (ASYM; n = 15; age = 21.13 ± 1.88 years, height = 1.84 ± 0.07 m, mass = 81.45 ± 13.26 kg), and healthy control (CON; n = 15; age = 19.60 ± 1.55 years, height = 1.84 ± 0.09 m, mass = 79.09 ± 12.37 kg). Three-dimensional biomechanics were collected during a double-limb jump-landing task. Kinematic (knee-flexion angle [KF]) and kinetic (vertical ground reaction force, internal knee-extension moment [KEM], patellar tendon force [FPT]) variables were analyzed as continuous waveforms during the stance phase for the involved limb. Mean values were calculated for each 1% of stance, normalized over 202 data points (0%–100%), and plotted with 95% CIs. Statistical significance was defined as a lack of 95% CI overlap for a minimum of a consecutive 3% of the stance phase. The SYM group had less KF than the CON group throughout the stance phase (8%–76%: Cohen d = 1.14 ± 0.12, mean difference [MD] = 15.83° ± 2.71°). The ASYM group had less KF than the CON group in the early (8%–13%: Cohen d = 0.99 ± 0.04, MD = 7.99° ± 0.39°; 21%–24%: Cohen d = 1.01 ± 0.01, MD = 11.11° ± 0.32°) and late (74%–94%: Cohen d = 0.96 ± 0.07, MD = 9.55° ± 1.13°) stance phases. The SYM group had a smaller KEM (6.5%–9%: Cohen d = 1.21 ± 0.08, MD = 0.04 ± 0.004 N·m/[Nbw·mht]) and less FPT (6%–9%: Cohen d = 1.15 ± 0.15, MD = 0.85 ± 0.15 body weight) than the CON group in the early stance phase. The SYM group also displayed a smaller KEM (38%–56%: Cohen d = 1.17 ± 0.06, MD = 0.03 ± 0.001 N·m/[Nbw·mht]) and less FPT (36%–60%: Cohen d = 1.22 ± 0.08, MD = 0.66 ± 0.05 body weight) than the ASYM group in the midstance phase. The SYM group demonstrated a patellar tendon load-avoidance profile compared with the ASYM and CON groups. The ASYM group showed no evidence of overloading compared with the CON group. Our findings support the need for individualized treatments for athletes with tendinopathy to maximize load capacity. [ABSTRACT FROM AUTHOR]

Byline: Daniel C. Herman, PhD (University of North Carolina, Chapel Hill, North Carolina, dpadua@email.unc.edu); Paul S. Weinhold, PhD (University of North Carolina, Chapel Hill, North Carolina, dpadua@email.unc.edu); Kevin M. Guskiewicz, [...]

Background: Supraspinatus strengthening is an important component of shoulder rehabilitation. Previous work has determined that the full-can and empty-can exercises elicit the greatest amount of supraspinatus activity. However, scapular kinematics [...]