Bone stress injuries of the talus in military recruits.

The purpose of the present study was to assess the incidence, anatomic distribution, and nature of fatigue bone stress injuries of the talus in military recruits based on magnetic resonance imaging (MRI). Military recruits referred to MRI examination due to exercise-induced ankle and/or foot pain were identified from the MRI archives. MR images of cases with bone stress injury findings in the talus were retrospectively re-evaluated concerning the anatomic location and type of the bone stress injury. During 96 months, fifty-one consecutive recruits displayed bone stress injuries of the talus in the population base of 117,149 person-years, yielding an incidence of 4.4 (3.2-5.5)/10,000 person-years. Bilateral injuries were seen in five of the patients. Of the 56 bone stress injuries, 40 occurred in the head, 15 in the body, and 5 in the posterior part of the talus. In four cases, both the head and the body were affected. Solitary, the talus was affected in 12 cases. In 44 cases, a stress injury was also present in other tarsal bones. Assessing the severity of the bone stress injury, a grade I-III injury was found in 46 and a grade IV injury with a fracture line in 10 of the cases. Injuries of the upper part of the body were associated with calcaneal stress injuries in 78% of the cases (P=0.03), and injuries of the head of the talus were associated with stress injuries in the naviculare in 60% of the cases (P=0.04). Age, sex, height, weight, body mass index, or physical fitness failed to reach statistical significance as risk factors for fatigue bone stress injuries of the talus. On MRI, the majority of the bone stress injuries of the talus were revealed in the head. A grade IV injury was discovered in 18% of the cases; in the remaining 82%, only grade I-III injuries were ascertained. In all locations, the lower grade bone stress injuries dominated. This study established the incidence of fatigue bone stress injury of the talus and indicated that these injuries are rare but not unseen in military recruits.