Notch morphology is a risk factor for ACL injury: a systematic review and meta-analysis

Importance Several bone morphological parameters have been identified in the scientific literature as risk factors for sustaining an anterior cruciate ligament (ACL) injury; however, a clear consensus on which are the most predisposing factors is still missing. Aim This systematic review and meta-analysis aims to investigate the association between bone morphological parameters and the risk of sustaining an ACL injury. Evidence review We conducted a comprehensive search using PubMed, Cochrane Library, Scopus, CINAHL and SPORTDiscus databases from 2005 until 2015. Two authors independently searched for relevant studies that assessed the association between bone morphology and ACL injury. Other search sources were used for hand-searching additional potential studies and the reference list of recent studies was screened. The methodological quality of the included studies was assessed through an adapted scale for radiological studies. A fixed-effects or random-effects model was used accordingly to estimate the mean differences with 95% CIs regarding the association of ACL injury with intercondylar notch (ICN) width, notch width index (NWI) and tibial slopes. Findings 23 studies were included for analysis comprising a total of 3452 participants, 1681 with an ACL injury and 1763 with an intact ACL. The ACL-injured individuals had narrower ICN width (p<0.001), smaller NWI (p=0.005) and steeper tibial slope (p