Insufficiency fractures of the tibia and fibula

Objective: Insufficiency fractures (IF) occur when normal or physiological muscular activity stresses a bone that is deficient in mineral or elastic r esistance. IF of the tibia and fibula are probably less common than IF of t he ribs, vertebrae, hip, pelvis, and distal ulna, and therefore they are fr equently underrecognized and mistaken for other conditions. Our aim was to analyze the main features and outcome of IF of the tibia and fibula in pati ents attending our Rheumatology Service. Methods: IF was considered when occurring spontaneously or with minimal tra uma. Between January 1984 and July 1997, 25 patients were diagnosed as havi ng IF of the tibia and fibula. The main predisposing factors, clinical feat ures, therapy, and outcome were retrospectively reviewed. Results: All the patients except four were women (mean age, 66 +/- 12 years ). Three cases were diagnosed between 1984 and 1990 (0.42 cases/year) and 2 2 between 1991 and 1997 (three cases/year). Eighteen patients had an underl ying condition: rheumatoid arthritis (RA, 13 cases), psoriatic arthritis (2 ), systemic lupus erythematosus (SLE) (1), kidney transplant (1), and Crohn 's disease (1). Eleven patients had osteoporotic fractures in other locatio ns. Risk factors for osteoporosis were corticosteroids (13 cases), prolonge d immobilization (10), early menopause (2), and methotrexate therapy (10). All patients had pain on weight bearing and marked functional impairment, 1 6 had local inflammatory signs, and 10 had deformity. In only five patients the diagnosis of IF was considered at the first examination. The diagnosti c delay was 76 +/- 117 days (median, 21). The initial radiograph was diagno stic in 20 patients, and in the remaining the diagnosis was made by compute d tomography (CT) scan (three cases), magnetic resonance imaging (MRI) (1), and bone scan (1). IF were located as follows: tibia (10 cases), fibula (s even), tibia and fibula (eight). Nineteen patients were treated with conser vative management, four received no specific treatment, and two required su rgery. Sixteen patients were hospitalized for a mean period of 12 +/- 8 day s. Most patients had complete recovery. The high frequency of IF seen in RA patients is probably due to the severe disease in patients treated by our Service and that such patients have a higher risk for osteoporosis and its complications. Conclusions: IF of the tibia and fibula are probably more common than previ ously thought. They usually occur in patients with underlying rheumatic dis eases, mainly RA, and are frequently mistaken for other joint and bone cond itions. Despite a frequent delay in diagnosis, they have a good prognosis w ith conservative management. Nonetheless, a higher index of suspicion may a void unnecessary investigations and treatments. Copyright (C) 1999 by W.B. Saunders Company.