Risk factors for lower limb injury in female team field and court sports : A systematic review, meta-analysis, and best evidence synthesis

Background
Identifying risk factors for lower limb injury is an important step in developing injury risk reduction training and testing for player monitoring. Female athletes are distinct from male athletes, warranting separate investigation into risk factors.

Objective
To systematically review the literature and synthesise the evidence for intrinsic risk factors for lower limb injury in female team field and court sports.

Methods
Five online databases were searched from inception to April 2020. To be eligible for inclusion, studies were required to be a prospective study presenting intrinsic risk factors for lower limb injury in female team field or court sport athletes. Risk of bias was assessed using the Quality of Prognosis Studies tool.

Results
Sixty-nine studies, capturing 2902 lower limb injuries in 14,492 female athletes, and analysing 80 distinct factors met the inclusion criteria. Risk factors for any lower limb injury included greater body mass (standardised mean difference [SMD] = 0.24, 95% confidence interval [95% CI]  0.18–0.29), greater body mass index (BMI) (SMD = 0.22, 95% CI  0.05–040), older age (SMD = 0.20, 95% CI  0.09–0.31), greater star excursion balance test (SEBT) anterior reach distance (SMD = 0.18, 95% CI   0.12–0.24), and smaller single-leg hop distance (SMD = − 0.09, 95% CI  − 0.12 to − 0.06). Lower knee injury and osteoarthritis outcome score (KOOS) increased the risk of knee injury. Anterior cruciate ligament (ACL) injury risk factors included prior ACL injury (odds ratio [OR] = 3.94, 95% CI  2.07–7.50), greater double-leg postural sway (SMD = 0.58, 95% CI   0.02–1.15), and greater body mass (SMD = 0.25, 95% CI  0.12–0.39). Ankle injury risk factors included smaller SEBT anterior reach distance (SMD = − 0.13, 95% CI  − 0.14 to − 0.13), greater single-leg hop distance asymmetry (OR = 3.67, 95% CI   1.42–9.45), and slower agility course time (OR = 0.20, 95% CI 0.05–0.88). Remaining factors were not associated with injury or had conflicting evidence.

Conclusion
Prior injury, older age, greater body mass, and greater BMI are risk factors for lower limb injury in female athletes. Limited evidence showed an association between KOOS, SEBT anterior reach, single-leg hop distance and asymmetry, double-leg postural sway, agility, and lower limb injury. PROSPERO ID: CRD42020171973.