The Role of Muscle in Knee Stability

Study Overview
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Brief Summary
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This project aims to compare the difference in muscle strength, muscle elasticity and muscle coordination of quadriceps and hamstring muscle and their association with knee biomechanics during single leg hop landing in patients with anterior cruciate ligament reconstruction.

Detailed Description
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In Hong Kong, over 3000 cases of Anterior Cruciate Ligament Reconstruction (ACLR) are operated annually to restore knee stability. Despite recovery of knee passive laxity and muscle strength, dynamic knee stability is often not restored. In additional to muscle strength, muscle elasticity and muscle coordination may also play an important role in knee stability. However, there is no evidence regarding the changes in muscle elasticity after ACLR and its contribution to dynamic knee stability. This study is a cross-sectional study designed to compare the the difference in muscle strength, muscle elasticity and muscle coordination of quadriceps and hamstring muscle in 30 ACLR patients and investigate its relationship with knee biomechanics during single leg hop landing. Patient selection was base on medical records and subjective knee functional scores. Patient enrollment and informed consent was conducted first. Muscle strength was measured by isokinetic muscle testing(Biodex) at two speeds. Muscle elasticity was assessed by ultrasound shear wave elastography. Muscle coordination evaluated by electromyography(EMG) and knee biomechanics including kinematics and kinetics was measured by 3D motion analysis system(VICON) and all the assessments were done in CUHK-ORT Sports Injury Research Laboratory in the Prince of Wales Hospital, Hong Kong. All data was collected and analyzed by qualified personnel.

Official Title
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The Role of Quadriceps and Hamstring Muscles in Knee Stability During Single Leg Hop Landing in Patients With Anterior Cruciate Ligament Reconstruction

Conditions
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Anterior Cruciate Ligament Injuries

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: (1) Male aged 18-35 (2) With pre-injury activity level of more than 6 in Tegner score (3) Within their post-operative 6-18 months (4) Without injury history for the contralateral limb Exclusion Criteria: (1) With concomitant fracture, meniscus injury or chondral lesion (2) With preoperative radiographic signs of arthritis (3) With revision ACL surgery (4) With injury history of the spine or hamstring strain during the past 6 months.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| knee biomechanics during single leg hop landing | knee kinematics(peak knee flexion, knee valgus, knee internal rotation, knee flexion excursion, valgus excursion and internal excursion) and kinetics(vertical ground reaction force, knee extension moment, knee valgus moment) were collected by 3D motion analysis system(VICON) during the landing phase of single leg hop test | post-operatively 6-18 months | 
| muscle strength | muscle peak torque of knee extension and knee flexion at 60°/s and 180°/s tested with isokinetic mode by Biodex | post-operatively 6-18 months | 
| muscle elasticity | muscle shear elastic modulus of vastus medialis, rectus femoris, vastus lateralis, semimembranosus,semitendinosus and biceps femoris was measured by ultrasound shear wave elastography | post-operatively 6-18 months | 
| muscle coordination | muscle activity level and onset time of vastus medialis, vastus lateralis, semimembranosus,and biceps femoris was assessed by electromyography(EMG) during the landing phase of single leg hop test | post-operatively 6-18 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| knee laxity | anterior displacement of the tibia was measured using the KT-1000 arthrometerat 134 N with knee flexed at around 20° | post-operatively 6-18 months | 
| subjective knee function | International Knee Documentation Committee (IKDC) scoring system, which is consisted of 10 questions about symptoms and activity ranging from 0 to 100 | post-operatively 6-18 months | 
| Psychological readiness for return-to-play | Anterior Cruciate Ligament-Return to Sport after Injury(ACL-RSI)-on a scale from 0 to 100 | post-operatively 6-18 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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muscle strength, muscle elasticity, muscle coordination, knee stability