Pathogenesis of Fifth Metatarsal Stress Fractures in College Soccer Players

Abstract

Category: Sports Introduction/Purpose: The pathogenesis of fifth metatarsal stress fractures remains uncertain. We hypothesized that physical characteristics and environmental factors, which have received limited attention in the literature thus far, might be involved in the development of such fractures. To test our hypothesis, we performed a medical checkup and a survey of the living environment of athletes in college soccer teams, and subsequently, we investigated the existence of fifth metatarsal stress fractures, and examined the differences between the injury group and the non-injury group. Methods: The survey and measurements were conducted in 273 male athletes from the same college soccer team between 2005 and 2013. A medical checkup, comprising assessment of stature, body weight, body mass index, arch height ratio, toe-grip strength, quadriceps angle, leg-heel angle, functional reach test, one-leg standing time with eyes closed, straight leg raise test, finger-floor distance, heel-to-buttock distance, ankle joint range of motion, and general joint laxity test, and a questionnaire survey were performed once a year. A survey was conducted at the time of injury that resulted in fifth metatarsal stress fractures. The study participants were separated into an injury group and a non-injury group, depending on whether they had a fifth metatarsal stress fracture. The measurement items and survey items were compared, and the association between the presence or absence of injury and the measurement items was analyzed. Results: Toe-grip strength was significantly weaker in the injury group, compared with the non-injury group, suggesting that a weak toe-grip is associated with fifth metatarsal stress fracture (p < 0.05). In addition, injury on the non-dominant leg was more frequent in the fifth metatarsal stress fracture injury group (p < 0.05). Between-group comparisons of the other items showed no statistically significant differences. Conclusion: The association between weak toe-grip strength and fifth metatarsal fracture suggests that a weak toe-grip may lead to an increase in the load applied onto the lateral side of the foot; this may cause mechanical stress on the bone. In addition, the effect of the non-dominant leg on the fifth metatarsal bone may need to be studied further.