Muscle atrophy contributes to quadriceps weakness after anterior cruciate ligament reconstruction

Lepley

2018

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Context: To quantify quadriceps weakness after anterior cruciate ligament reconstruction (ACLR), researchers have often analyzed only peak torque. However, analyzing other characteristics of the waveform, such as the rate of torque development (RTD), time to peak torque (TTP), and central activation ratio (CAR), can lend insight into the underlying neuromuscular factors that regulate torque development.Objective: To determine if interlimb neuromuscular asymmetry was present in patients with ACLR at the time of clearance to return to activity.Design: Cross-sectional study. Conclusions: Interlimb asymmetries at return to activity after ACLR appeared to be regulated by several underlying neuromuscular factors. We theorize that interlimb asymmetries in isometric and isokinetic quadriceps strength were associated with changes in muscle architecture. Reduced CAR, TTP, and RTD were also present, indicating a loss of motor-unit recruitment or decrease in firing rate.

Section: Isometric Interlimb Asymmetriesmentioning

confidence: 99%

Contribution of Neuromuscular Factors to Quadriceps Asymmetry After Anterior Cruciate Ligament Reconstruction

Johnson¹,

Lepley

2018

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“…Researchers [3][4][5]10,11,15,25 have reported deficits in patients with ACLR at RTA. We hypothesized that the ACL limb would exhibit strength and biomechanical deficits compared with the healthy limb at RTA and that these deficits would decrease over time.…”

Section: Discussionmentioning

confidence: 99%

“…In fact, at the time of RTA, patients often display substantial quadriceps weakness, with reported deficits exceeding 20% for the knee extensors when compared with the contralat-eral uninvolved limb. [3][4][5][6] Biomechanical asymmetries are also present in this population during basic movements such as walking and jogging. 7 Currently, no consensus exists on RTA criteria for patients with ACLR.…”

mentioning

confidence: 98%

Continued Improvements in Quadriceps Strength and Biomechanical Symmetry of the Knee After Postoperative Anterior Cruciate Ligament Reconstruction Rehabilitation: Is It Time to Reconsider the 6-Month Return-to-Activity Criteria?

Curran¹,

Lepley

2018

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Context:Patients who undergo anterior cruciate ligament reconstruction (ACLR) present with strength and biomechanical deficits at return to activity (RTA). Deficits in strength and biomechanical symmetry impair function during activity and may predispose patients to subsequent injury.Objective: To compare strength and biomechanical function in patients with ACLR at RTA and more than 12 months post-ACLR.Design: Descriptive laboratory study. Intervention(s): Strength was measured during knee extension and evaluated by the isometric and isokinetic quadriceps index. Biomechanical function was evaluated using symmetry values for sagittal-plane knee-joint rotations, changes in sagittal-plane knee-joint rotation, knee-extension moments, and changes in knee-extension moment that were recorded during a single-legged forward hop.Main Outcome Measure(s): Self-reported function was measured using the International Knee Documentation Committee Subjective Knee Evaluation Form. Participants were assessed at RTA (212.25 6 28.11 days) and more than 12 months post-ACLR (556.25 6 230.89 days).Results: At RTA, strength and biomechanical values were less than 80% symmetric. We observed improvements from RTA to more than 12 months post-ACLR for the isometric quadriceps index (F 1,18 ¼ 29.22, P , .001), isokinetic quadriceps index (F 1,18 ¼ 10.88, P ¼ .004), sagittal-plane knee-joint rotations (F 1,19 ¼ 9.58, P ¼ .006), change in sagittal-plane knee-joint rotations (F 1,19 ¼ 7.83, P ¼ .01), knee-extension moments (F 1,19 ¼ 5.73, P ¼ .03), change in knee-extension moments (F 1,19 ¼ 21.10, P , .001), and self-perceived function (F 1,19 ¼ 11.50, P ¼ .003). Of the 7 variables that showed improvement at more than 12 months post-ACLR, only 3 met the recommended criteria (!90%).Conclusions: Patients with ACLR showed asymmetry in strength and biomechanics at RTA. These asymmetries, along with self-perceived function, improved over time. However, despite improvements in strength and biomechanics at RTA, asymmetries of more than 10% were still present more than 12 months post-ACLR.

“…For participants in the ACL þ BB group and each image in which the BB appeared for both the tibia and the femur, the BB borders were traced by hand using ImageJ software (version 142q; National Institutes of Health, Bethesda, MD) and a pen tablet (model Intuos4; Wacom Technology Corporation, Vancouver, WA). 15 The maximum values for the tibial and femoral BBs among all slices were used to quantify the peak area (mm 2 ) of the contusion for the respective bones. A single investigator (A.C.T.)…”

Section: Magnetic Resonance Imaging and Bb Assessmentmentioning

confidence: 99%

Knee Frontal-Plane Biomechanics in Adults With or Without Bone Marrow Edema-Like Lesions After Anterior Cruciate Ligament Injury

Thomas

2017

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Context: Lateral subchondral bone bruises (BBs) occur frequently with anterior cruciate ligament (ACL) injuries. These BBs are associated with pain during weight bearing, leading individuals to increase medial tibiofemoral loading to alleviate pain laterally. Increased medial tibiofemoral loading may precipitate the development or progression of posttraumatic osteoarthritis; however, no in vivo biomechanical data exist to confirm that lateral BBs increase medial tibiofemoral loading as measured by the external knee-adduction moment (KAM).Objective: To determine whether lateral BBs after ACL injury increase the external KAM during walking.Design: Descriptive laboratory study. Intervention(s): We recorded peak KAM during 3 walking trials (1.1 6 0.6 m/s) in which participants walked over a force platform located in the field of view of a motion-capture system.Main Outcome Measure(s): Peak KAM was calculated during the first half of stance using standard inverse-dynamics analysis, averaged across trials, and examined via 1-way analysis of variance. Knee pain and function were determined from the International Knee Documentation Committee Subjective Knee Evaluation Form and compared among groups via the Kruskal-Wallis test.Results: Peak KAM did not differ among groups (ACL injury ¼ 0.14 6 0.07 NmÁkg À1 Ám À1 , ACL þ BB ¼ 0.21 6 0.08 NmÁkg À1 Ám À1 , control ¼ 0.20 6 0.08 NmÁkg À1 Ám À1 ; F 2,35 ¼ 3.243, P ¼ .052). Knee-pain frequency and severity were greater in the ACL-injury (frequency ¼ 2.55 6 1.81, severity ¼ 3.36 6 1.75; both P , .001) and ACL þ BB (frequency ¼ 3.58 6 2.81, severity ¼ 4.08 6 3.20; both P , .001) groups than in the control group (frequency ¼ 0.00 6 0.00, severity ¼ 0.00 6 0.00). Knee function was greater in the control group (100.00 6 0.00) than in the ACL-injury (59.35 6 17.31; P , .001) and ACL þ BB (46.46 6 25.85; P , .001) groups.Conclusions: The ACL þ BB groups did not walk with a greater external KAM than the ACL-injury or control groups. Thus, lateral tibiofemoral BB did not influence knee frontal-plane loading after ACL injury.