What is the difference between abduction and adduction?
To abduct is to move the limb away from the central line of the body: to adduct is to move it towards the central line of the body.
What muscles are involved in knee abduction?
Abduction of the knee involves the gluteus medius, gluteus minimus and tensor fascia lata.
Peer-reviewed papersQuote from peer-reviewed paper:
"....Controlling the frontal plane pelvic position during landing may help to avoid injurious ground reaction forces and consequent knee abduction moment....."
Citation: Ueno R, Navacchia A, DiCesare CA, Ford KR, Myer GD, Ishida T, Tohyama H, Hewett TE. Knee abduction moment is predicted by lower gluteus medius force and larger vertical and lateral ground reaction forces during drop vertical jump in female athletes. J Biomech. 2020 Apr 16;103:109669. doi: 10.1016/j.jbiomech.2020.109669. Epub 2020 Jan 27. PMID: 32019678; PMCID: PMC7149737.
What is the knee abduction moment?
During gait analysis the way the athlete's foot lands on the force plate during running, cutting and landing manoeuvres allows the measurement of the contribution of different forces acting through the knee.
Thus one can measure the 'abduction moment', or the contribution to landing that is absorbed by the abductors of the knee. By measuring these various moments, the examiner can determine how balanced the muscles are. These measurements can predict to some extent the likelihood of any one athlete developing patellofemoral pain or tearing their anterior cruciate ligament.
Peer-reviewed papersQuote from peer-reviewed paper:
"....In adolescent girls aged 13.3 years, >15 Nm of knee abduction load during landing is associated with greater likelihood of developing PFP. Also, in girls aged 16.1 years who land with >25 Nm of knee abduction load during landing are at increased risk for both PFP and ACL injury...."
Citation: Myer GD, Ford KR, Di Stasi SL, Foss KD, Micheli LJ, Hewett TE. High knee abduction moments are common risk factors for patellofemoral pain (PFP) and anterior cruciate ligament (ACL) injury in girls: is PFP itself a predictor for subsequent ACL injury? Br J Sports Med. 2015 Jan;49(2):118-22. doi: 10.1136/bjsports-2013-092536. Epub 2014 Mar 31. PMID: 24687011; PMCID: PMC4182160.