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SPORTS MEDICINE STRESS FRACTURES PAIN positive x-ray or CT
stress fracture
N spot, which is located in the central region of the proximal dorsal area of the bone (fig 3).
silent stress reaction
positive bone scan or MRI
stress reaction
BONE STRAIN Figure 2: Stress continuum of bone strain
DIAGNOSIS History Athletes typically present with an insidious onset of activity-related pain, often complaining of a mild ache that occurs after, or towards the end of a period of physical activity. The pattern differs from that of soft tissue injuries where pain decreases after a short period of exercise, such as a warm up (6).
A progressing stress fracture will
produce a more rapid onset of pain that lasts for an increased duration after training has finished, possibly persisting into activities of daily living (12). With continued loading and without activity modification the bony injury may progress to a complete or even displaced fracture (12). The latter being a career threatening event, early diagnosis is crucial for a successful outcome. Potentially the best method for attaining a diagnosis is a high level of awareness to the possibility of a stress fracture amongst players, coaches and clinicians.
Physical examination A lack of substantial findings and vague symptoms that often mimic other musculoskeletal complaints such as tendon or muscle injuries, make the diagnosis difficult. A careful history coupled with a complete and meticulous physical examination is the key to accurate identification. Examination typically reveals
Investigations Since clinical evaluation may not be definitive, diagnostic imaging has a pivotal role in assessment and typically the first step is to use conventional x-rays as they are cheap and widely available. However, x-rays have a low sensitivity for stress fractures and are often no more helpful than clinical assessment. They will only show a stress fracture that has been present for some time (13). According to the literature up to 85% of stress fractures are overlooked in the first radiograph and up to 50% are overlooked in the second radiograph (12). In athletes with a concerning history and negative plain films, advanced imaging should be obtained.
anterior extensor hallucis longus ‘N’ spot
reproducible points of bony tenderness at the fracture site, assuming the location is directly palpable. It is therefore important to be aware of surface anatomy to comprehensively examine the affected area and compare to the uninjured side. Certain bones, such as the tibia, fibula, and metatarsals, lend themselves well to direct palpation because of the absence of overlying muscle. In contrast, stress fractures of the femoral neck and the pars interarticularis of the spine make direct palpation impossible and as a result of vague symptoms a delay in diagnosis is common (11).
Clinical tests for stress fractures such as pain associated with the athlete standing on their toes (navicular), hop test (tibia and navicular), fulcrum test (femur), and spinal extension test (pars interarticularis) are useful but not as reliable as direct palpation (6). Clinical suspicion of a navicular stress fracture should be high when palpation reveals a tender
tibial tendon
Figure 3: The ‘N’spot location on the navicular
Bone scans are very sensitive and demonstrate uptake in the affected bone well before radiographic changes occur (fig 4). However a bone scan is nonspecific and other bony abnormalities such as tumours and osteomyelitis may produce similar pictures (14). Since a bone scan is non-specific localising the exact site precisely may prove difficult, especially in a region like the foot where several small bones are in close proximity.
TIP: Magnetic resonance imaging (MRI) is used more frequently as the primary means of investigation.
MRI sensitivity is similar to that of a bone scan, however, it is much more precise in delineating the exact location and extent of the injury (1). Typically early MRI findings will demonstrate
Figure 4: Bone scan showing increase uptake in the navicular 23
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