A 22-year-old college student comes to the office due to a 1-week history of right lower leg pain. She has mild dull pain at rest that becomes sharp and "bothersome" with exercise. She is an avid runner and has been preparing for an upcoming marathon event for the past 2 months. Her shoe has recently been bothering her, especially on the lateral side of the right foot. The patient has no other medical problems or history of recent trauma. Physical examination shows point tenderness and localized swelling over the right lower tibial border.
Which of the following is most likely to be seen on plain x-rays of the right lower extremity?

Question

A 22-year-old college student comes to the office due to a 1-week history of right lower leg pain.  She has mild dull pain at rest that becomes sharp and "bothersome" with exercise.  She is an avid runner and has been preparing for an upcoming marathon event for the past 2 months.  Her shoe has recently been bothering her, especially on the lateral side of the right foot.  The patient has no other medical problems or history of recent trauma.  Physical examination shows point tenderness and localized swelling over the right lower tibial border. 
Which of the following is most likely to be seen on plain x-rays of the right lower extremity?

Quizplus · Accepted Answer

Explanation: This patient, with lower leg pain and tibial tenderness in the setting of a vigorous running regimen, has features suggesting a tibial stress fracture. Stress fractures are a common injury in athletes (up to 15% incidence in runners) and nonathletes who suddenly increase their activity. Besides runners, stress fractures are common in ballet dancers, basketball and soccer players, and military recruits. The risk of stress fractures can be increased by activity-related (eg, excessive training or improper footwear), biomechanical (eg, weak calf muscles or high arched feet), and metabolic (eg, demineralized bone from hormonal or nutritional diseases) factors. Stress fractures occur due to a sudden increase in repeated tension or compression without adequate rest, which eventually breaks the bone. Patients usually initially develop medial tibial stress syndrome ("shin splints") without tibial tenderness; further activity can cause progression to a complete or incomplete fracture, resulting in tibial tenderness on palpation. A stress fracture is diagnosed clinically when there is pain at a specific area that increases with jumping or running and is associated with local swelling and point tenderness on examination. Initial plain x-rays of the tibia have low sensitivity and are negative during the first few weeks in over half of the cases. Possible abnormalities on x-ray may take up to 4 weeks to become apparent and include bone sclerosis, cortical thickening, periosteal elevation, and visible fracture line (Choices A, B, D, and E). If the initial x-ray is negative, patients may be managed empirically based on clinical findings. However, if a definitive diagnosis is needed, MRI is preferred over bone scan or ultrasound as it can show the fracture line that extends through the cortex into the medullary line. MRI can also identify ligament, muscle, and cartilage injuries. However, MRI findings may be persistently abnormal for up to 1 year after the stress fracture has healed. Educational objective: Tibial stress fractures are common in athletes and nonathletes who suddenly increase their physical activity. Clinical features include pain, localized tenderness, and swelling. Plain x-ray is <50% sensitive for stress fractures, especially in the first 2-3 weeks after the onset of symptoms. References: Stress fractures in athletes (http://www.ncbi.nlm.nih.gov/pubmed/17414993)

A 22-Year-Old College Student Comes to the Office Due to a 1-Week