OBJECTIVE:To investigate the effects of swelling on postural control and patient-reported outcomes in individuals with chronic ankle instability (CAI). DESIGN:Cross-sectional study. SETTING:Controlled laboratory. PARTICIPANTS:A total of 60 participants-20 CAI individuals with swelling (swelling), 20 CAI individuals without swelling (nonswelling), and 20 healthy controls (control)-were recruited. INDEPENDENT VARIABLES:Group (swelling, nonswelling, and control). MAIN OUTCOME MEASURES:Participants performed 3 trials of single-leg hop-to-stabilization and single-leg stance tasks, along with patient-reported outcomes. A one-way analysis of variance was used to assess group differences in dynamic and static postural control and patient-reported outcomes. RESULTS:The swelling group exhibited worse dynamic postural control in vertical stability index and dynamic postural stability index compared with the nonswelling ( P = 0.03, P = 0.04) and control ( P < 0.01 and P < 0.01) groups. The nonswelling group showed similar dynamic postural control with the control group. Swelling ( P < 0.01 and P < 0.01) and nonswelling ( P = 0.01 and P < 0.01) groups showed worse static postural control center of pressure mediolateral velocity and center of pressure anteroposterior velocity compared with the control group. Swelling and nonswelling groups showed differences in patient-reported outcomes about ankle function and instability compared with the control group, but there was no difference in patient-reported outcomes between the swelling and nonswelling groups themselves. CONCLUSION:Ankle swelling contributes to altered neuromuscular control, resulting in worse dynamic postural control, but affects neither static postural control nor patient-reported outcomes in CAI individuals.

PURPOSE:To investigate differences in neuromechanics during walking between individuals with chronic ankle instability (CAI) reporting high and low chronic pain, and healthy controls, with a focus on stance-phase joint kinematics and muscle activation patterns. METHODS:Sixty physically active participants were classified into three groups: CAI with high pain (n=20), CAI with low pain (n=20), and controls (n=20). Pain severity was determined using the Foot and Ankle Outcome Score pain subscale. Three-dimensional lower extremity kinematics and surface electromyography activation of six lower extremity muscles were recorded during overground walking at self-selected speed. Functional data analysis was used to identify stance-phase differences between groups. RESULTS:Relative to controls, both CAI groups exhibited reduced activation of the peroneus longus and gluteal muscles across multiple stance subphases, with more widespread reductions in the high pain group-particularly diminished tibialis anterior (0-15%), gluteus medius (15-45%), and gluteus maximus (0-20%, 30-50%). Compared with the low pain group, the high pain group demonstrated greater ankle dorsiflexion during midstance (20-45%), greater knee flexion in early stance (5-15%) and preswing (85-95%), and greater hip flexion throughout early stance (0-20%). Increased hip adduction occurred in midstance (30-50%). CONCLUSIONS:Individuals with CAI who report greater pain severity demonstrate distinct, time-specific gait deviations and greater neuromuscular inhibition, which may extend beyond the effects of instability alone. These findings highlight the potential role of pain in influencing gait adaptations in chronic ankle instability and underscore the importance of considering pain in the evaluation and rehabilitation of these individuals.

CONTEXT:Chronic ankle instability (CAI) patients exhibit altered movement patterns during jump landing/cutting movements. Persistent pain is one of the residual symptoms that may affect movements. Calculating joint energetics affected by chronic pain offers a novel method to understand how chronic pain influences energetics of lower extremity joints in CAI patients. OBJECTIVE:To identify the effects of chronic pain on lower extremity energy dissipation and generation during jump landing and cutting in patients with CAI. DESIGN:Cross-sectional study. SETTING:Laboratory. PATIENTS OR OTHER PARTICIPANTS:Fifteen CAI patients with higher pain (6 men and 9 women; age = 22.1 ± 2.1 years, height = 1.74 ± 0.09 m, mass = 71.3 ± 10.6 kg, pain = 66.9 ± 9.4), 15 patients with CAI and lower pain (6 men and 9 women; age = 22.3 ± 2.1 years, height = 1.74 ± 0.08 m, mass = 70.1 ± 10.7 kg, pain = 89.3 ± 2.6), and 15 healthy control individuals (6 men and 9 women; age = 21.3 ± 1.7 years, height = 1.73 ± 0.08 m, mass = 70 ± 10.3 kg, pain = 100 ± 0). MAIN OUTCOME MEASURE(S):Ground reaction force data were collected during 5 trials of maximal jump landing/cutting tasks. Joint power was defined as the product of angular velocity and joint moment. Energy dissipation and generation by the ankle, knee, and hip joints were calculated by integrating regions of the joint power curve. RESULTS:CAI patients with higher pain displayed less ankle energy dissipation (P = .013 and P = .018) and generation in the ankle (P = .002 and P = .028) than CAI patients with lower pain and healthy control individuals during the jump landing/cutting phase. CAI patients with higher pain showed more hip energy generation than CAI patients with lower pain (P = .038) and healthy control individuals (P = .013) during the cutting phase. CONCLUSIONS:CAI patients with higher pain changed both energy dissipation and generation in the lower extremities, reducing the burden of the ankle joint during jump landing/cutting and having a hip-dominant compensatory strategy during the cutting phase. Our results suggest that chronic pain could be one of the factors that affect motor strategies in the CAI population.

Time spent in moderate-to-vigorous physical activity (MVPA) is linked to biomarkers associated with knee osteoarthritis development following anterior cruciate ligament reconstruction (ACLR). It remains unclear whether distinct MVPA trajectories exhibited during the first 12 months post-ACLR are linked to early markers of knee osteoarthritis. PURPOSE:To identify distinct MVPA trajectories between 2 and 12 months post-ACLR and compare tibiofemoral articular cartilage composition changes and patient-reported outcomes (PROs) between trajectory groups. METHODS:Device-measured MVPA was collected at 2, 4, 6, and 12 months post-ACLR in individuals with ACLR. MVPA trajectories were identified using group-based trajectory modeling. Cartilage composition was measured preoperatively and at 12 months post-ACLR using change in T1ρ (ΔT1ρ) magnetic resonance imaging relaxation times in the lateral (lateral femoral condyle [LFC], lateral tibia) and medial (medial femoral condyle, medial tibia) femoral and tibial compartments. The Knee Injury and Osteoarthritis Outcomes Score (KOOS) was used to assess PROs preoperatively and at 2, 4, 6, and 12 months post-ACLR. Differences in KOOS subscale scores and ΔT1ρ were compared between MVPA trajectory groups. RESULTS:We identified a consistent MVPA (74.5%) and a high-increasing MVPA trajectory (25.5%). The high-increasing trajectory group engaged in more MVPA at all time points compared with the consistent group. The high-increasing trajectory group demonstrated greater ΔT1ρ in the LFC (i.e., deleterious changes in cartilage composition, P = 0.006) and higher KOOS sport compared with the consistent MVPA group ( P = 0.037). CONCLUSIONS:Individuals between 2 and 12 months post-ACLR most commonly engage in the consistent MVPA trajectory. The high-increasing MVPA trajectory group demonstrated worsening LFC cartilage composition. These data indicate that high MVPA in the first 12 months post-ACLR may be linked to deleterious knee tissue changes but not worse PROs.

BACKGROUND:Individuals with chronic ankle instability (CAI) exhibit deficits in postural control and muscle activation, with bilateral changes suggesting central alterations in sensorimotor function. However, differences in postural control and muscle activation between bilateral and unilateral CAI remain unclear. Understanding these differences is crucial for developing targeted rehabilitation strategies. RESEARCH QUESTION:Do individuals with bilateral CAI, unilateral CAI, and healthy controls have differences in postural control and muscle activation? METHODS:18 individuals with bilateral CAI (bilateral), 18 individuals with unilateral CAI (unilateral), and 18 healthy controls (control) were recruited. To assess center of pressure (COP) and integrated electromyography (iEMG), participants performed 3 trials of single-leg stance tasks and lower extremity muscle activation was recorded simultaneously. One-way ANOVA was used to assess differences in the self-reported functional outcomes, postural control, and muscle activation among the three groups. RESULTS:The bilateral group showed worse postural control in COP mediolateral velocity and COP anteroposterior velocity compared to the unilateral and control groups. However, the unilateral group showed similar postural control with the control group. The bilateral group showed greater iEMG in the tibialis anterior compared to the unilateral and control groups. The unilateral group showed lower iEMG in the tibialis anterior compared to the control group. SIGNIFICANCE:Individuals with bilateral and unilateral CAI show significant differences in postural control and muscle activation during single-leg stance, suggesting that the central nervous system may process sensorimotor function differently. Understanding these differences can guide personalized treatments, which may enhance patient outcomes and reduce recurrent sprain risk.

CONTEXT:Individuals with chronic ankle instability (CAI) have deficits in postural control. Previous studies assessing postural control have been limited by minimal environmental perturbations. The purpose of this study is to identify the effects of virtual reality (VR)-based perturbation on static postural control among CAI individuals, copers, and healthy controls. DESIGN:Cross-sectional study. METHODS:A total of 60 participants (20 individuals with CAI, 20 copers, and 20 healthy controls) performed 3 trials of a single-leg stance for 10 seconds with eyes open and eyes closed (EC) and VR. Static postural control was analyzed by 2-way analysis of variance. RESULTS:CAI individuals showed worse static postural control in the center of the pressure mediolateral range and ellipse area under VR than copers and healthy controls. Copers showed better static postural control in the center of pressure mediolateral range and in the ellipse area under VR and EC than individuals with CAI and healthy controls. Both VR and EC resulted in worse static postural control than eyes open across the 3 groups. However, there were no differences in static postural control between VR and EC within each group. CAI individuals demonstrated worse static postural control under VR than copers and healthy controls, whereas copers exhibited better postural stability under VR than CAI individuals and healthy controls. CONCLUSIONS:VR may serve as a means for understanding differences in postural control mechanisms in individuals with CAI and copers.

CONTEXT:Individuals with chronic ankle instability (CAI) have deficits in force accuracy in evertors and hip abductors due to impaired neuromuscular control. Individuals with CAI rely more on visual information during force accuracy following lateral ankle sprain. To identify the effects of using stroboscopic glasses following a 4-week rehabilitation on force accuracy of ankle evertors, invertors, and hip abductors and visual reliance in individuals with CAI. DESIGN:Randomized controlled clinical trial. METHODS:A total of 50 CAI individuals were assigned to a strobe or control group. The strobe group wore stroboscopic glasses during rehabilitation, while the control group did not. Force accuracy was measured at 10% and 20% of maximum voluntary isometric contraction (MVIC). Romberg ratios were calculated as strobe vision/eyes open to identify visual reliance. RESULTS:The strobe group showed a greater force accuracy in 10% of evertors MVIC under the strobe vision than the control group. The strobe group showed a greater force accuracy in 10% of evertors MVIC under the strobe vision than with the eyes open. The strobe group showed an improved Romberg ratio in 10% of evertors MVIC between the pretest and posttest. CONCLUSION:Stroboscopic glasses may offer clinicians a new means to reduce visual reliance, allowing them to utilize the somatosensory system more effectively around the foot/ankle complex. This may indicate reweighting of sensory systems in CAI individuals during rehabilitation.

BackgroundAlthough individuals with anterior cruciate ligament reconstruction (ACLR) are at high risk for posttraumatic osteoarthritis, mechanisms underlying the relationship between running and knee cartilage health remain unclear.ObjectiveWe aimed to investigate how 30 min of running influences femoral cartilage thickness and composition and their relationships with running biomechanics in patients with ACLR and controls.MethodsTwenty patients with ACLR (time post-ACLR: 14.6 +/- 6.1 months) and 20 matched controls participated in the study. A running session required both groups to run for 30 min at a self-selected speed. Before and after running, we measured femoral cartilage thickness via ultrasound imaging. A MRI session consisted of T2 mapping.ResultsThe ACLR group showed longer T2 relaxation times in the medial femoral condyle at resting compared with the control group (central: 51.2 +/- 16.6 vs. 34.9 +/- 13.2 ms, p = 0.006; posterior: 50.2 +/- 10.1 vs. 39.8 +/- 7.4 ms, p = 0.006). Following the run, the ACLR group showed greater deformation in the medial femoral cartilage than the control group (0.03 +/- 0.01 vs. 0.01 +/- 0.01 cm, p = 0.001). Additionally, the ACLR group showed significant negative correlations between resting T2 relaxation time in the medial femoral condyle and vertical impulse (standardized regression coefficients = -0.99 and p = 0.004) during running.ConclusionsOur findings suggest that those who are between 6 and 24 months post-ACLR have degraded cartilage composition and their cartilage deforms more due to running vGRF.

Patients with chronic ankle instability (CAI) consistently display postural control alterations, which may result from sensorimotor dysfunction. This study aimed to compare muscle activity in the lower extremity and postural control among individuals with CAI, copers and uninjured controls during a static balance test. A total of 57 physically active participants were categorized into three groups (CAI, copers and controls) and performed a single-leg balance test with two visual conditions: eyes open and eyes closed. Muscle activity in six lower extremity muscles and center of pressure (CoP) variables were recorded and analyzed. Patients with CAI exhibited greater muscle activity in the medial gastrocnemius and gluteus maximus compared to controls or copers, regardless of the visual condition. Copers displayed increased gluteus medius activity compared to controls. Additionally, all groups demonstrated increased muscle activity and CoP variables when visual feedback was disrupted. These findings suggest that patients with CAI may have less effective recruitment of motor units during static balance. On the other hand, greater muscle activity in the gluteus medius in copers may represent a coping mechanism to avoid further ankle injuries. Further research on muscle activity during dynamic postural control is warranted to explore sensorimotor alterations in patients with CAI.

CONTEXT:Therapeutic interventions for individuals with chronic ankle instability (CAI) are recommended to improve muscle strength, postural control, and range of motion. However, their effects on neuromechanics during a drop landing remain unclear. In addition, even though therapeutic interventions with stroboscopic glasses appear to effectively improve postural control, how they affect landing neuromechanics remains unclear. OBJECTIVE:To identify the effect of balance training with stroboscopic glasses on neuromechanics during a single-legged drop landing in patients with CAI. DESIGN:Randomized controlled clinical trial. SETTING:Laboratory. PATIENTS OR OTHER PARTICIPANTS:A total of 50 participants with CAI were randomly assigned to 1 of 2 groups: strobe (n = 25; age = 22 ± 3 years, height = 174.7 ± 8.2 cm, mass = 71.8 ± 12.2 kg) or control (n = 25; age = 21 ± 2 years, height = 173.1 ± 8.3 cm, mass = 71.1 ± 13.5 kg). INTERVENTION(S):The 4-week rehabilitation (3 sessions per week) included hop-based tasks and single-legged stance. The strobe group wore stroboscopic glasses during the training, whereas the control group did not. MAIN OUTCOME MEASURE(S):Ankle-, knee-, and hip-joint kinematics and 4 lower extremity muscle activations 150 milliseconds before and after initial contact during a single-legged drop landing in the 2 groups. RESULTS:The strobe group showed greater eversion (from 150 milliseconds before to 30 milliseconds after initial contact) and dorsiflexion (from 30 to 96 milliseconds after initial contact) angles and peroneal longus (from 35 milliseconds before to 5 milliseconds after initial contact) and tibialis anterior (from 0 to 120 milliseconds after initial contact) activation in the posttest than the pretest. CONCLUSIONS:Patients with CAI who underwent a 4-week rehabilitation with stroboscopic glasses demonstrated changes in neuromechanics, including increased ankle-dorsiflexion and -eversion angles and tibialis anterior and peroneus longus activation, during a single-legged drop landing. This finding suggests that use of stroboscopic glasses during rehabilitation could help patients with CAI develop safe landing mechanics.

CONTEXT:Individuals with chronic ankle instability (CAI) demonstrate altered movement patterns when their vision is disturbed during simple tasks, such as single-legged standing and walking. However, it remains unclear whether visual disruption by stroboscopic glasses alters movement patterns during landing-cutting movements, considered highly demanding sport maneuvers that mimic a typical athletic movement. OBJECTIVES:To identify altered lower extremity kinematics and muscle activation when vision is disrupted by stroboscopic glasses during landing-cutting tasks in individuals with CAI. DESIGN:Case-control study. SETTING:Laboratory. PATIENTS OR OTHER PARTICIPANTS:A total of 18 individuals with CAI (age = 22.3 ± 2.3 years, height = 1.75 ± 0.1 m, mass = 72.5 ± 9.8 kg) and 18 matched healthy controls (age = 21.7 ± 2.3 years, height = 1.75 ± 0.1 m, mass = 71.9 ± 10.3 kg). INTERVENTION(S):All participants performed 5 trials of a landing-cutting task with (SV) and without (NSV) stroboscopic glasses. MAIN OUTCOME MEASURE(S):Frontal- and sagittal-plane lower extremity kinematics and 6 lower extremity muscle activations during the stance phase of a landing-cutting task in the SV and NSV conditions. RESULTS:Individuals with CAI demonstrated more ankle-inversion angle from 18% to 22% and from 60% to 100% of the stance phase and more peroneus longus activation from initial contact to 18% of the stance phase under the SV condition than under the NSV condition. We observed no differences in knee- and hip-joint angles between the visual conditions for both groups. CONCLUSIONS:When wearing stroboscopic glasses, individuals with CAI showed altered movement patterns, including increased ankle-inversion angle and peroneus longus activation during the stance phase of a landing-cutting task. The results suggest that they may lack the ability to reweight sensory information to adapt their movement to visual disruption.

Clinical Scenario: Ankle sprains are highly common and can lead to chronic ankle instability (CAI). Individuals with CAI have a variety of sensorimotor impairments including poor postural control and altered sensory organization strategies. Visual occlusion modalities, if worn during neuromuscular control exercises, may facilitate greater postural control gains and a more appropriate sensory organization strategy. However, a cumulative review of the ability of visual occlusion modalities (e.g., stroboscopic goggles) to impair postural control and thus demonstrate the potential to facilitate greater postural gains has not yet been completed. Clinical Question: Does stroboscopic vision impair postural control in those with and without CAI, and if so, is the impairment comparable between the groups? Summary of Key Findings: Regardless of how postural control was assessed, stroboscopic vision impaired postural control relative to an eyes open (i.e., no goggles) condition. All studies demonstrated that those with and without CAI were impacted equally. Stroboscopic vision resulted in postural control impairments comparable to an eyes closed in some but not all studies. Clinical Bottom Line: Stroboscopic vision impairs postural control in both those with CAI and uninjured controls. Strength of Recommendation: There is moderate-quality evidence (Grade B) that stroboscopic vision impairs postural control in those with CAI and uninjured controls.

OBJECTIVE:To identify the effects of chronic pain levels on static and dynamic postural (DP) control in individuals with chronic ankle instability (CAI). DESIGN:Cross-sectional study. SETTING:Controlled laboratory. PARTICIPANTS:Sixty participants were divided into the following 3 groups: 20 high pain individuals with CAI (high pain), 20 low pain individuals with CAI (low pain), and 20 healthy controls (control). INDEPENDENT VARIABLES:Groups (CAI with high pain, CAI with low pain, and control) and visual conditions (eyes open and closed) for single-leg stance. MAIN OUTCOME MEASURES:Participants performed single-leg stance with eyes open and closed, the star excursion balance test, and single-leg hop to stabilization. RESULTS:The high pain group experienced worse self-reported outcomes, including Foot and Ankle Ability Measure activities of daily living and sports, than the low pain and control groups. Regardless of visual condition, both the high and low pain groups exhibited decreased static postural control in mediolateral (ML) compared with the control group. Specifically, the high pain group showed decreased static postural control in ML under closed eyes compared with the low pain and the control groups. The high pain group showed less reach distance than the control group and increased DP control in vertical and overall DP stability index compared with the low and control groups. CONCLUSIONS:Chronic pain can significantly affect both static and DP control in individuals with CAI. Therefore, clinicians should consider chronic pain as one of the factors affecting postural control in individuals with CAI.