Effects of Exercise on Lower Extremity Muscle Function After Anterior Cruciate Ligament Reconstruction

Kuenze, Christopher; Hertel, Jay; Hart, Joseph M.

doi:10.1123/jsr.22.1.33

Cited by 32 publications

(35 citation statements)

References 47 publications

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“…32 For the effect of ACLR on quadriceps CAR, the Cohen d effect size was 1.2; therefore, a minimum of 20 participants per group was needed 32 to find differences while maintaining a statistical power of 80% and an a level of .05.…”

Section: Lsi ¼ Aclr Limb Uninvolved Limb ð2þmentioning

confidence: 99%

Persistent Neuromuscular and Corticomotor Quadriceps Asymmetry After Anterior Cruciate Ligament Reconstruction

Kuenze

Hertel

Weltman

et al. 2015

Journal of Athletic Training

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105

116

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Context: Return to activity in the presence of quadriceps dysfunction may predispose individuals with anterior cruciate ligament reconstruction (ACLR) to long-term joint degeneration. Asymmetry may manifest during movement and result in altered knee-joint-loading patterns; however, the underlying neurophysiologic mechanisms remain unclear.Objective: To compare limb symmetry of quadriceps neuromuscular function between participants with ACLR and participants serving as healthy controls.Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: A total of 22 individuals with ACLR (12 men, 10 women) and 24 individuals serving as healthy controls (12 men, 12 women).Main Outcome Measure(s): Normalized knee-extension maximal voluntary isometric contraction (MVIC) torque (Nm/ kg), quadriceps central activation ratio (CAR) (%), quadriceps motor-neuron-pool excitability (Hoffmann reflex to motor wave ratio), and quadriceps active motor threshold (AMT) (% 2.0 T) were measured bilaterally and used to calculate limb symmetry indices for comparison between groups. We used analyses of variance to compare quadriceps Hoffmann reflex to motor wave ratio, normalized knee-extension MVIC torque, quadriceps CAR, and quadriceps AMT between groups and limbs.Results: The ACLR group exhibited greater asymmetry in knee-extension MVIC torque (ACLR group ¼ 0.85 6 0.21, healthy group ¼ 0.97 6 0.14; t 44 ¼ 2.26, P ¼ .03), quadriceps CAR (ACLR group ¼ 0.94 6 0.11, healthy group ¼ 1.00 6 0.08; t 44 ¼ 2.22, P ¼ .04), and quadriceps AMT (ACLR group ¼ 1.13 6 0.18, healthy group ¼ 1.02 6 0.11; t 34 ¼À2.46, P ¼ .04) than the healthy control group.Conclusions: Asymmetries in measures of quadriceps function and cortical excitability were present in patients with ACLR. Asymmetry in quadriceps strength, activation, and cortical excitability persisted in individuals with ACLR beyond return to recreational activity. Measuring the magnitude of asymmetry after ACLR represents an important step in understanding long-term reductions in self-reported function and increased rate of subsequent joint injury in otherwise healthy, active individuals after ACLR.Key Words: quadriceps activation, limb symmetry index, transcranial magnetic stimulation Key PointsThe anterior cruciate ligament reconstruction (ACLR) group exhibited a weaker, less activated quadriceps and less cortical excitability in the reconstructed limb than in the contralateral limb and in the limbs of the healthy control group. Asymmetry in quadriceps strength, activation, and cortical excitability persisted in individuals with ACLR beyond return to recreational activity. Chronic asymmetry indicated reduced dynamic force absorption at the knee and may explain the increased rate of knee reinjury and chronic joint degeneration after ACLR.

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Section: Lsi ¼ Aclr Limb Uninvolved Limb ð2þmentioning

confidence: 99%

Persistent Neuromuscular and Corticomotor Quadriceps Asymmetry After Anterior Cruciate Ligament Reconstruction

Kuenze

Hertel

Weltman

et al. 2015

Journal of Athletic Training

Self Cite

105

116

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“…1 A history of ACL-R is also associated with a greater risk for chronic degeneration of the articular tissues of the knee, which leads to early-onset osteoarthritis. 2,3 Posttraumatic changes in quadriceps motor function may be associated with long-term disability in patients who have had ACL-R. 4,5 A wealth of evidence has suggested that ACL-R causes both immediate and long-term changes in quadriceps motor function, which can manifest as weakness, 6,7 inhibition, 6,8 and diminished power 9,10 and motor control. 11,12 Impaired quadriceps motor function is concerning to clinicians and scientists due to the primary role the quadriceps play in lower extremity locomotion, force attenuation, and functional stability about the knee.…”

mentioning

confidence: 99%

Knee-Extension Torque Variability and Subjective Knee Function in Patients With a History of Anterior Cruciate Ligament Reconstruction

Goetschius¹,

Hart

2016

Journal of Athletic Training

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Context: When returning to physical activity, patients with a history of anterior cruciate ligament reconstruction (ACL-R) often experience limitations in knee-joint function that may be due to chronic impairments in quadriceps motor control. Assessment of knee-extension torque variability may demonstrate underlying impairments in quadriceps motor control in patients with a history of ACL-R.Objective: To identify differences in maximal isometric knee-extension torque variability between knees that have undergone ACL-R and healthy knees and to determine the relationship between knee-extension torque variability and selfreported knee function in patients with a history of ACL-R.Design: Descriptive laboratory study. Setting: Laboratory. Patients or Other Participants: A total of 53 individuals with primary, unilateral ACL-R (age ¼ 23.4 6 4.9 years, height ¼ 1.7 6 0.1 m, mass ¼ 74.6 6 14.8 kg) and 50 individuals with no history of substantial lower extremity injury or surgery who served as controls (age ¼ 23.3 6 4.4 years, height ¼ 1.7 6 0.1 m, mass ¼ 67.4 6 13.2 kg).Main Outcome Measure(s): Torque variability, strength, and central activation ratio (CAR) were calculated from 3-second maximal knee-extension contraction trials (908 of flexion) with a superimposed electrical stimulus. All participants completed the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, and we determined the number of months after surgery. Group differences were assessed using independent-samples t tests. Correlation coefficients were calculated among torque variability, strength, CAR, months after surgery, and IKDC scores. Torque variability, strength, CAR, and months after surgery were regressed on IKDC scores using stepwise, multiple linear regression.Results: Torque variability was greater and strength, CAR, and IKDC scores were lower in the ACL-R group than in the control group (P , .05). Torque variability and strength were correlated with IKDC scores (P , .05). Torque variability, strength, and CAR were correlated with each other (P , .05). Torque variability alone accounted for 14.3% of the variance in IKDC scores. The combination of torque variability and number of months after surgery accounted for 21% of the variance in IKDC scores. Strength and CAR were excluded from the regression model.Conclusions: Knee-extension torque variability was moderately associated with IKDC scores in patients with a history of ACL-R. Torque variability combined with months after surgery predicted 21% of the variance in IKDC scores in these patients.

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“…103,132 After ACLR, individuals also experience alterations in walking gait compared to healthy individuals years after surgery, including reductions in peak knee flexion angle, knee flexion moment, and knee extension moment during stance phase. 60,199,202 121,195 Therefore, it is imperative that return to sport assessments for this population include functional assessments during exercise when risk of second injury is greatest and neuromuscular control is compromised.…”

Section: Discussionmentioning

confidence: 99%

“…73,106,107,144 Patients with ACLR experience a significant decline in quadriceps strength compared to both the contralateral limb and healthy matched limb, 144,190 leading to asymmetric quadriceps strength. 91,174,208 These strength deficits in the involved limb may be from atrophied quadriceps 105 after surgical intervention causing a shift towards fatigue-resistant quadriceps 103,132,183 or may be changes in quadriceps activation. 73,144 Quadriceps activation failure is common bilaterally years after ACLR 73 even when quadriceps atrophy is no longer present.…”

Section: 137mentioning

confidence: 99%

“…Graded treadmill exercise has been used previously to test cardiopulmonary fitness, 1,204 however has been used for knee rehabilitation because it increases quadriceps activation 110 and is a popular choice to induce neuromuscular fatigue. 38,44,103 These types of aerobic protocols are not applicable to sporting environments that require both high-intensity aerobic and anaerobic components. 163 …”

Section: Applying Exercise Protocols To the Athlete Population (For Amentioning

confidence: 99%

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Biomechanical Adaptations After Fatiguing Exercise in Healthy and ACL Reconstructed Individuals

Slater

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Effects of Exercise on Lower Extremity Muscle Function After Anterior Cruciate Ligament Reconstruction

Cited by 32 publications

References 47 publications

Persistent Neuromuscular and Corticomotor Quadriceps Asymmetry After Anterior Cruciate Ligament Reconstruction

Persistent Neuromuscular and Corticomotor Quadriceps Asymmetry After Anterior Cruciate Ligament Reconstruction

Knee-Extension Torque Variability and Subjective Knee Function in Patients With a History of Anterior Cruciate Ligament Reconstruction

Biomechanical Adaptations After Fatiguing Exercise in Healthy and ACL Reconstructed Individuals

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