Lower Extremity Alignment and Dynamic Control With Associated Injury Risk in College Athletes With Knee Hyperextension

Investigators expect to recruit 100 subjects into 2 group- control group and knee hyperextension group (KH group). In knee hyperextension group, investigators will include college athletes having knee hyperextension alignment, no lower extremity injuries in past three months, and participating in jump-landing activities. Control group will match the gender, age, height, weight and sports to KH group. Inclusion criteria is the same as KH group, except the knee hyperextension angle is <5⁰ in control group. Every subjects will receive the first time assessment and follow up by filling the injury-follow-up form every months for about four months.

At the first assessment, investigators will measure lower extremity alignments include pelvic angle in sagittal plane, hip anteversion, tibiofemoral angle, knee hyperextension angle in supine and standing position, tibial rotation angle, and navicular drop; lower extremity muscle flexibility include rectus femoris, hamstrings, gastrocnemius, soleus, iliotibial band; lower extremity muscle strength include hip, knee, muscle group; dynamic control task will record tibio-femoral acceleration, angle change ground reaction force and EMG muscle firing during vertical jump and drop jump.

Inclusion criteria

• age ≥ 20 years old
• knee hyperextension ≥ 5⁰
• participate in jump- landing sports
• training at least 3 days per week
• no lower extremity injury last 3 months

Exclusion criteria

• having knee surgery before
• In the past three months have occurred lower extremity musculoskeletal injury leading the person can't participate in training or competition for at least three days