Risk factors for developing jumper's knee in sport and occupation: a review

A systematic search of the international scientific literature was performed until November 2008 in the scientific databases (a) Medline, (b) Embase, and (c) SportDiscus. All types of studies were included. The search strategy retrieved ten articles about risk factors in sport that met the inclusion criteria. Risk factors that could be identified are; playing volleyball (4 studies), playing basketball (3 studies), training and playing volleyball/basketball more than 12 hours per week (2 studies), in combination with weight-bearing activities of at least 5 hours per week (1 study) and playing or training on a hard surface (1 study). No studies were found regarding occupation that fulfilled the inclusion criteria.Playing volleyball and basketball has a positive association with the onset or worsening of jumper's knee. Other risk factors are training and playing hours of at least 12 hours per week and/or in combination with weight training of at least 5 hours per week, and/or with playing or training on a hard surface. We did not find a specific occupational risk factor.Jumper's knee is among the most frequent injuries in sports [1,2] and it has upset many professional sporting careers. The prevalence of jumper's knee ranged from 30%–51% in volleyball [3-10]; 25%–32% in basketball [2,8]; to 0% for cycling and wrestling [2]. The term "jumper's knee" was first introduced by Blazina et al. [11]: a gradual insidious onset of aching in the knee centered over the infrapatellar or suprapatellar region, especially localized to the superior or inferior poles of the patella. It is generally accepted that jumper's knee is caused by a dynamic overload, mainly eccentric, of the extensor mechanism of the knee joint [12-14]. Jumper's knee is associated with sports and sporting activities, especially with repetitive activities such as jumping, climbing, kicking or running [12-14]. Therefore, jumper's knee is perhaps a misleading term.Not only with sports and sporting activities, but a