Tibial stress fracture in a runner

Clinical History

The patient, a female runner, presented with pain at the right lower leg, aggravating by walking.There was no previous history of direct trauma

Imaging Findings

The patient presented with pain at the right lower leg, aggravating by walking. There was no previous history of direct trauma The pain was mild but subsequently the pain worsened and occurred earlier, limiting participation in sports activities. She reported pain upon palpation or percussion of the affected area. The plain radiograph showed normal findings. The MR imaging protocol included gradient T2 weighted, Axial T1 weighted (Fig 3) and STIR in coronal plane (Fig 1). It showed oedema in the soft tissues around the diaphysis of the tibia, and a fracture line. No soft tissue mass was seen. CT examination (Fig 2) showed a horizontally oriented, linear lucency in the posterior tibial cortex, with adjacent periosteal new bone formation. CT confirmed the diagnosis of a stress fracture.

Discussion

Stress fractures are overuse injuries of bone. These fractures, which may be incomplete or complete, result from repetitive subthreshold loading that, over time, exceeds the bone's intrinsic ability to repair itself.
Range of the annual incidence of stress fractures among athletes and military recruits is 5-30%. Stress fractures, like most overuse injuries, typically are multifactorial in etiology; thus, if the diagnosis has been made or is suspected, it is important to determine the risk factors. Intrinsic risk factors are low BMD, lower limb malalignment, foot structure height, tall stature, muscle fatigue, strength imbalance, pathologic bone states, menstrual/hormonal irregularities and genetic predisposition. Extrinsic risk factors are excessive volume or intensity of training in sport disciplines – for example, runners are prone to tibial shaft stress fractures, whereas tennis players appear to be most vulnerable to navicular injuries, and volleyball players may be at a relatively increased risk of pars interarticularis injuries. Worn-out training shoes, inadequate nutrition, calcium, vitamin D medication usage - for example, chronic steroid use.
Note that no single physical examination test is sufficiently sensitive and specific to permit the unequivocal diagnosis of a stress fracture.
It is very important to exclude differential diagnosis like tumours of the bone, especially osteoid osteomas etc.
Imaging studies can help the physician confirm the suspected clinical diagnosis. Conventional radiographic findings are often unremarkable, particularly early in the continuum that leads from stress reaction to stress fracture. In some cases, conventional radiography remains negative, despite clear diagnostic evidence of fracture on bone scan or cross-sectional imaging. Other conventional radiographic findings include an area of cortical lucency that suggests a nonhealing stress fracture. Computed tomographic (CT) examination is a useful diagnostic imaging tool. A 3-phase bone scan (scintigraphy) may be indicated if conventional radiographic findings are negative or nondiagnostic and the clinical suspicion of stress fracture remains high. The bone scan is diagnostic of stress fracture if focal isotope uptake occurs in the area of clinical interest on the third phase of the scan. Scintigraphy is extremely sensitive but the drawbacks of scintigraphy include a relative lack of specificity and anatomic resolution. Because of the limitations inherent to scintigraphy, MRI may be a reasonable first-line imaging procedure. MRI provides greater anatomic detail of the area in question, and fat-suppressed (short TI inversion recovery [STIR]) and water-weighted (T2) signal sequences permit detection of marrow edema and/or periosteal reaction occurring during the earliest stages of stress fracture formation with a level of sensitivity that rivals bone scanning. Treatment consists of activity restriction to minimize symptoms before engaging in a program of increasingly demanding strengthening and conditioning exercise, leading to an eventual return to play in 8-12 weeks. Some authors recommend immobilization as initial therapy. Failure of nonoperative care warrants consideration of surgical intervention. Options include reamed intramedullary nailing and internal fixation with bone grafting. Postoperative recovery time averages 6 months. Complications of stress fracture may include avascular necrosis, nonunion, malunion, posttraumatic arthrosis, and persistent disabling pain.

Differential Diagnosis List

Final Diagnosis

Tibial stress fracture in a runner

URL:	https://www.eurorad.org/case/7349
DOI:	10.1594/EURORAD/CASE.7349
ISSN:	1563-4086