PT - JOURNAL ARTICLE AU - Takayuki Miyamori AU - Masashi Nagao AU - Ryuichi Sawa AU - Steve Tumilty AU - Masafumi Yoshimura AU - Yoshitomo Saita AU - Hiroshi Ikeda AU - Kazuo Kaneko TI - Playing football on artificial turf as a risk factor for fifth metatarsal stress fracture: a retrospective cohort study AID - 10.1136/bmjopen-2018-022864 DP - 2019 Feb 01 TA - BMJ Open PG - e022864 VI - 9 IP - 2 4099 - http://bmjopen.bmj.com/content/9/2/e022864.short 4100 - http://bmjopen.bmj.com/content/9/2/e022864.full SO - BMJ Open2019 Feb 01; 9 AB - Objective The fifth metatarsal stress fracture is a common injury among football players. Although several risk factors have been proposed, the association between the playing surface and development of fifth metatarsal stress fractures (MT-5) has not been evaluated. We conducted an epidemiological study using a computer-based survey to investigate the association between the playing surface and development of MT-5.Methods This study included 1854 football players, of which 41 experienced MT-5 within the past 24 months. Baseline demographic data and the percentage of time spent playing on artificial turf and clay fields were compared between the non-MT-5 and MT-5 player groups, and the risks for development of MT-5 associated with the playing surfaces were estimated by univariate and multivariate analyses.Results There were significant differences in body mass index, years of play, playing categories and playing time on artificial turf between non-MT-5 and MT-5 groups (p<0.05). Generalised estimating equations analyses adjusted for multiple confounders demonstrated that relative to the risk of playing <20% of the time on each surface, the OR (OR: 95% CI) for MT-5 for playing on artificial turf >80% of the time increased (3.44: 1.65 to 7.18), and for playing on a clay field 61%–80% of the time, the OR decreased (0.25: 0.11 to 0.59).Conclusions A higher percentage of playing time on an artificial turf was a risk factor for developing MT-5 in football players. This finding could be beneficial for creating strategies to prevent MT-5.