Table 1

A snapshot of the current binary categorisation of intrinsic and extrinsic risk factors for non-contact anterior cruciate ligament injury*

Modifiable risk factorsNon-modifiable risk factors
Environmental Environmental
 Meteorological conditions (E)Playing situation (E)
 Playing surface (E)Opponent behaviour (E)
 Rules (E)Unanticipated events during play (E)
 Referees (E) Anatomical
 Coaching (E)Q angle (I)
Equipment Navicular drop (I)
 Footwear (E)Structural knee valgus (I)
 Knee braces (E)Postural alignment (I)
Anatomical Notch size, ACL geometry and properties (I)
 Foot pronation (I)Tibial slope angle (I)
 Body composition and body mass index (I)Generalised joint hypermobility or laxity (I)
Neuromuscular Hormonal
 Dynamic knee valgus (I)Menstrual phase (I)
 Muscle strength (I)Hormone concentrations (I)
 Muscle strength ratios (I) Demographic
 Muscle activation patterns (I)Age (I)
 Muscle stiffness (I)Maturation (I)
 Physical fitness and muscle fatigue (I)Previous contralateral knee ACL injury (I)
 Skill level (I)Familial history and genetics (I)
 Neuromuscular control (I)Sex (I)
 Proprioception (I)Height (I)
Psychological (I)Race (I)
 Personality (I)Sports played (I)
 Stress response (I)
  • *Table collated and modified from 92,103; and based on 31,104-107.

  • E, extrinsic; I, intrinsic.