Overview of PECOS eligibility criteria
| Participants | Human female athletes (defined as one who takes part in an individual or organised team sport wherein: (i) they compete regularly against others; (ii) excellence and achievement are emphasised and (iii) systematic intensive training is required32) and female exercisers (defined as one who engages in physical activity with the will to: (i) augment their fitness level; (ii) improve their health; (iii) ameliorate their physique and (iv) acquire or improve skills33) of reproductive age (ie, postmenarche and premenopausal) will be included. Specifically, eumenorrheic, naturally menstruating women, women with menstrual irregularities (eg, oligomenorrhoea, polymenorrhoea, amenorrhoea, anovulatory and luteal phase deficient cycles) and hormonal contraceptive users (eg, combined and progestogen-only OCPs, injections, implants, patches, intra-uterine systems) will be included; with pregnant and perimenopausal women excluded. Participants must not be using any form of medication known to affect ovarian hormone profiles (with the exception of hormonal contraceptives) or the musculoskeletal system. |
| Exposures | Of interest will be habitual exposures affecting the endogenous ovarian hormone status of the participants; that is, menstrual cycle and associated disturbances and hormonal contraceptives. |
| Comparators | Where relevant, hormonal contraceptive users will be compared with non-hormonal contraceptive users. |
| Outcomes | Outcomes relating to the physical assessment of AK laxity (primary outcomes) and the occurrence of non-contact ACL injuries (secondary outcomes). The primary outcomes are focused on micro changes (ie, physiological changes to the AK laxity that potentially occur due to changes in ovarian hormone concentrations) and the secondary outcomes are focused on macro changes (ie, number of non-contact ACL injuries that may potentially occur due to micro changes). AK laxity refers to the degree of tightness/looseness of the AK in a sagittal plan; in the knee, ligaments are present to connect and stabilise the various bones that are present by keeping the knee joint flexible enough to move but also firm enough to provide support. It is measured using (i) clinical examination (eg, Lachman test—manual test to assess the AK laxity; subjective measure) and (ii) equipment designed to evaluate the AK laxity by quantifying the anterior displacement of the anterior tibial tubercle relative to the femur when a predefined anteriorly directed force is applied, from the upper calf (eg, arthrometers; objective measure). Within this systematic review and meta-analysis, we will exclusively focus on studies reporting primary non-contact ACL injuries (defined as sudden-onset injuries resulting from a non-contact mechanism showing no evidence of direct or indirect physical disruption or perturbation of the player’s movement pattern by an external source.34 |
| Study designs | Observational studies will be considered for inclusion if they meet the following inclusion criteria: (i) published, in full, in a peer-reviewed journal; (ii) have the objective of assessing changes in AK laxity in response to phases of the menstrual cycle, menstrual irregularities and/or hormonal contraceptive use and (iii) report the incidence of ACL injuries aligned with phases of the menstrual cycle, menstrual irregularities and/or hormonal contraceptive usage. Cohort studies and case–control studies will be included when reporting primary outcomes (ie, the physical assessment of AK laxity). Cross-sectional studies, cohort studies and case–control studies will be included when reporting secondary outcomes (ie, the occurrence of non-contact ACL injuries). Case studies, review articles, protocol papers, editorials, conference abstracts and commentaries will be excluded. |
AK, anterior knee; OCPs, Oral contraceptive pills.