The Impact of Knee Anterior Translation Variability Across the Menstrual Cycle on Knee Kinematics During Walking, Running and Single Leg Squatting
Aim
Identify if fluctuations in knee laxity (anterior translation) occur across the menstrual cycle and then understand if these fluctuations in knee laxity impact on movement kinematics.
Background
Injury to the ACL is devasting requiring prolonged rehabilitation often following surgery to repair the ligament, there is also a relatively high secondary ACL injury rate within two years and a large rate of failure to return to preinjury activity levels. Alongside these issues, there are long-term health consequences, individuals who injury their ACL have a significantly increased risk of developing patellofemoral and tibiofemoral joint osteoarthritis. Females have been reported has having up to a x8 elevated risk of injuring their ACL’s. This elevated risk has been related to specific deleterious movements and forces applied to the knee (increased knee abduction angle and moment, reduced knee flexion and increased knee anterior translation) during landing and cutting manoeuvres; the fluctuations of specific hormone concentrations during the menstrual cycle may have a role in these movement changes. Oestrogen upregulates relaxin receptors in ligaments, the levels of Oestrogen vary across the menstrual cycle with the highest concentrations in the pre-ovulatory period (day 7-14 of a 28-day cycle). Research has found knee laxity (anterior translation) to be greater during this period and this increased translation to be linked to changes in knee abduction and hip internal rotation moments during cutting and landing, both of which have been linked to ACL injury. Alongside this several retrospective studies found ACL injury rates are higher in the pre-ovulatory period. What has yet to be investigated is if the potential change in translation related to menstrual cycle phase brings about a change in knee laxity which can be directly related to changes in knee kinematics.
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