Aim and Hyopthesis: This systematic review and the metanalysis were performed to investigate the relation between football activity and the potential risk of knee osteoarthritis (possible occupational disease). It was hypothesised that soccer players suffer more than controls from knee osteoarthritis also in cases with an absence of documented major injuries.
The review and the metaanalysis were performed accordingly to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. On 2014.02.01 a search was conducted within the medical databases PubMed, Medline, Cochrane, EMBASE und Web-of-Science. A total of 4,649 papers underwent a "Title-Abstract-Review". Finally 6 publications were included in the metaanaylsis.
There were no longitudinal community-based studies as well as no Cochrane Reviews regarding the risk of knee osteoarthritis in soccer players. After adjustment of major injuries of the knee, soccer players have a slightly increased risk for knee osteoarthritis: relative risk 1.3 (95 % CI 1.0 - 1.7); I(2) = 37.4 %; p = 0.002. In contrast, in studies without differentiation of injured and non-injured knees, the relative risk was significantly increased: 2.9 (95 % CI 2.0 - 4.1); I(2) = 56.3 %; p < 0.001.
Soccer players are a very heterogeneous group. The soccer player's knee undergoes different loadings including minor and major injuries. But the individual load also strongly depends on the player's status, his position within the football field and many other factors. In the absence of a major trauma the soccer player has only a slightly increased risk for the development of osteoarthritis. Thus we conclude that an injury in professional football does not fulfil the characteristics of an occupational disease.