As these two cases show, stress fractures of the femoral neck are frequently associated with young adults who are physically active and running is considered a predominant cause of these types of fractures. The abnormal forces causing the excessive bone resorption may result from increased training intensity, hard training surfaces, inappropriate footwear or incorrect training techniques.25
However, factors like bone composition, vascular supply and poor anatomical alignment of the feet might play an important role as well.11
The higher reported incidence of stress fractures among female athletes could be triggered by a triad of eating disorders, amenorrhoea and osteoporosis.3 26
Johnson et al27
estimated the global incidence of stress injuries in sports to approximately 2% in men and 7% in women. Benell et al28
found a two to fourfold increased risk of stress fractures in women with menstrual disturbances and delayed menarche. Furthermore, Brunet et al29
reported that female athletes have up to four times higher risk of bone stress injury. However, some authors reported an equal risk of developing stress fractures in both sexes.30 31
Both of our patients had experienced deep pain in the groin region for several weeks before the acute displacement of the fracture. Although they might belong to risk groups, because of the age and high intensity training the symptoms were diagnosed as tendinitis and treated with NSAIDs. As we know, deep pain localised to the hip or groin region is the most prevalent symptom of stress fractures of the femoral neck. At the early stages the pain is present only during exercise. However, as the bone resorption progresses, the patient could experience intensive pain also at rest.3 32 33
Examination with plain radiographs was only performed in the second case and turned out to be normal. More advanced diagnostic procedures like CT, MRI or radionuclide scanning were not carried out in any of the cases. Although plain radiographs are a routine examination, they have only 15–35% sensibility; thus, making the stress fracture difficult to discover in the first weeks after the onset of symptoms.3
That is why careful clinical examination and previous history with focus on recent activities and nutritional status are essential in the diagnostic process.32 33
Radionuclide bone-scanning and MRI have nearly 100% sensitivity and should, therefore, represent ‘the golden standard’ for detecting an early stage stress fracture.31
Devas et al34
described two types of fatigue fractures of the femoral neck: (1) the compression type, which initially appears on the inferior aspect, and (2) the tension type, which initially appears on the superior aspect of the femoral neck. Compression fractures seem to be more common in young patients, are usually stable and might be treated conservatively. However, the tension type is more unstable and, therefore, is associated with a significant risk of displacement.33
In our cases, the preoperative radiographs showed displaced, tension-type fracture of the femoral neck.
Although the fractures healed in both of our reported cases, the displacement of stress fractures of the femoral neck might, in spite of proper treatment, lead to avascular necrosis of the femoral head. In a study performed by Visuri et al
, four cases of avascular necrosis were reported in a group of 12 patients treated with internal fixation.20
Johansson et al
reported 16 stress fractures of the femoral neck treated with internal fixation and three of the patients developed avascular necrosis.35
Both studies show a significant risk of necrosis after displacement of the fracture; thus emphasising the importance of early diagnosis and aggressive treatment in order to achieve proper fracture-healing and good quality of life afterwards.
Measures to avoid stress fractures of the femoral neck should include proper nutrition, suitable training techniques, training intensity and appropriate foot wear. Close follow-up of athletes with a history of deep groin pain during exercise might, together with swift examination by MRI or radionuclide scanning, be essential in preventing displacement of fractures and possible avascular necrosis of the femoral head as a consequence.
- Identification of risk groups, like hard-training young adults, especially female athletes with eating disorders and consequent menstrual disturbances and osteoporosis, is important.
- There should be close follow-up of athletes with history of deep groin pain during exercise.
- Plain radiographs have only 15–35% sensitivity in early stages.
- Radionuclide scanning and MRI is ‘golden standard’ and have nearly 100% sensitivity.
- Proper nutrition, suitable training techniques, training intensity and appropriate foot wear are important measures to prevent stress fractures.