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- PATIENTS AND METHODS
Stress fractures, although commonly seen by health care professionals caring for athletes, are a source of major and increasing importance for rheumatologists, because pain is the main symptom (1–4). Stress fractures can be classified into 2 groups. Fatigue fractures and insufficiency fractures (1–5). The first may occur when repetitive muscular forces or stresses are applied to a normal bone (6–8), and are most common in adolescents, athletes, and military recruits (3–5, 7–10). Insufficiency fractures, in contrast, are found when physiologic forces are applied to a weakened bone in patients with diseases such as osteoporosis, osteomalacia, and fibrous dysplasia (3, 5). Although insufficiency fractures and fatigue fractures are somehow overlapping conditions, in this report we have focused on patients with a diagnosis of fatigue fracture. Knowledge of the activities and risk factors associated with these disorders may increase clinical suspicion and help direct an appropriate evaluation. Thus, to further investigate this condition we have examined the etiologic factors, clinical features, diagnostic approach, and outcome in a series of consecutive patients with fatigue fracture diagnosed at the single referral hospital for a defined population in northwest Spain over a 14-month period.
- Top of page
- PATIENTS AND METHODS
Fatigue fractures are still not very familiar to many clinicians, including rheumatologists. The recognition of this entity may be particularly difficult in some cases, as initial plain radiographic findings may be normal (14). They result from repetitive, cyclic loading of bone, which overwhelms the reparative ability of the skeletal system (7, 8). Due to the higher incidence among athletes (15), the effect of exercise on bone fractures has received much attention in recent years. Among female athletes, a number of risk factors including low bone mineral density, menstrual irregularities, dietary factors, and prior fractures have been associated with an increased risk for fatigue fractures (16). In adolescents and children, fatigue fractures have been reported (17) and in these cases a differential diagnosis with other conditions such as osteomyelitis, eosinophilic granuloma, osteogenic sarcoma, and Ewing sarcoma is required (18).
Our prospective study constitutes an attempt to examine the frequency and features of fatigue fractures in a series of adults diagnosed at the single rheumatology division for a defined population. Thus, the present study provides the first analysis on epidemiologic, clinical, and laboratory features, as well as treatment and outcome in a series of unselected patients with fatigue fracture. Due to this, patients with osteoporotic insufficiency fractures were excluded.
Our division provides medical care to patients complaining of rheumatic features who attend both the outpatient rheumatology clinic and the emergency department of our hospital. This fact gives us more comprehensive information on patients presenting at the hospital with musculoskeletal manifestations. The relative frequency of fatigue fractures with regard to all patients diagnosed as having monarthritis within the study period was 3%.
As previously reported in our series, women outnumbered men. However, none of the patients was engaged in sporting activities. In addition, we did not diagnose adolescents with this problem during the period of study. In most cases, these fractures mimicked a monarthritis due to their proximity to the joints.
In athletes, fatigue fractures were more commonly found in tibia, metatarsal, femur, and tarsal navicular bones (2, 3, 15). In the present series, besides the former sites, midtarsal bones, talus, and calcaneus were also involved. It is difficult to explain the reasons for fatigue fractures in our series of nonathletes. It is possible that a history of repetitive loading, including prolonged standing and walking at work, and alcoholism in individuals with normal or low body mass index might have played a role.
Conventional radiographs continue to be used as a primary method for the diagnosis of fatigue fractures. However, as in our cases, initial plain radiographs may be normal (19). Although bone scintigraphy has generally been considered the gold standard test for the diagnosis of fatigue fractures (2), in our experience MRI proved to be more precise at detecting the injury site, extent, and characteristics of the lesion early in the course of the disease (14).
Rest with progressive reintroduction of activity is the treatment chosen for the majority of patients with fatigue fractures (19). However, as observed in our series, when the condition is untreated for a long time, osteoarthritis and chronic pain are likely to occur.
In conclusion, fatigue fractures are not exceptional in unselected adults. Rheumatologists should consider this diagnosis in patients presenting with monarthritis.