Magnetic resonance imaging findings in patients with fibular stress injuries

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SCIENTIFIC ARTICLE

Magnetic resonance imaging findings in patients with fibular stress injuries Michael Woods & Richard Kijowski & Matthew Sanford & James Choi & Arthur De Smet

Received: 31 January 2008 / Revised: 28 February 2008 / Accepted: 3 March 2008 / Published online: 13 June 2008 # ISS 2008

Abstract Objective The objective was to evaluate magnetic resonance imaging (MRI) findings in patients with fibular stress injuries. Materials and Methods The study group consisted of 20 patients with clinically diagnosed fibular stress injuries who were evaluated with MRI. Radiographs were performed in 14 of the 20 patients. The MRI examinations and radiographs were retrospectively reviewed in consensus by two musculoskeletal radiologists. Results All 20 patients with clinically diagnosed fibular stress injuries had periosteal edema and bone marrow edema within the fibula on MRI. The periosteal reaction and bone marrow edema were present within the distal fibula in 14 patients, the middle fibula in 1 patient, and the proximal fibula in 5 patients. The periosteal reaction was located on the anterior cortex in 1 patient, the posterior cortex in 4 patients, the lateral cortex in 11 patients, and circumferentially distributed throughout the cortex in 4 patients. Nine patients had abnormal T1 and T2 signal intensity within the fibular cortex. Initial and follow-up radiographs showed periosteal reaction in 15% and 50% of patients with fibular stress injuries respectively. Conclusions The majority of fibular stress injuries involve the lateral cortex of the distal fibula. Keywords Stress fractures . Fibula . Radiographs . MRI

M. Woods (*) : R. Kijowski : M. Sanford : J. Choi : A. De Smet Department of Radiology, University of Wisconsin, Clinical Science Center–E3/311, 600 Highland Avenue, Madison, WI 53792-3252, USA e-mail: [email protected]

Introduction Stress injuries represent a spectrum of osseous abnormalities that occur in response to chronic repetitive stress applied to healthy bone. Stress injuries are most commonly seen in athletes and military recruits who are involved in strenuous running activities [1–4]. Chronic repetitive stress results in an imbalance between osteoclastic and osteoblastic activity, which ultimately weakens bone. If the repetitive stress continues, repair mechanisms may be overwhelmed and a true fracture may develop. However, most stress injuries represent stress reaction and show no evidence of a break in the continuity of bone on histologic analysis [5–8]. The vast majority of stress injuries involve the tibia, followed in order of decreasing frequency by the metatarsals, fibula, navicular, femur, and pelvis [1–4]. Fibular stress injuries are relatively uncommon. In a review of multiple clinical series of stress injuries in athletes and military recruits, the fibula was noted to be involved in an average of 11.9% of cases [1–4]. Most previous studies have reported only the clinical and radiographic findings in patients with fibular stress injuries [9–11]. The magnetic resonance imaging (MR