IS Case 215: 1. Stress fracture of the right distal tibia and 2. Bilateral shin splints.
Imaging Sciences URMC 2008
Publication Date: 2009-05-22
Patient is an 18-year-old female with three weeks of bilateral calf pain, right greater than left. Patient denies any injury or trauma. She is currently playing lacrosse and has continued to try and practice and play despite the pain. The pain is along the medial aspect of the gastroc on the right side and is getting worse. Patient has pain with walking, standing, running, and jumping, but no significant pain with rest and is not awakening her at night. She has gone to three visit of physical therapy, but it has not significantly helped.
Radiographic images of the lower extremities demonstrated no acute fractures or dislocations. Nuclear imaging with a three phase bone scan demonstrated a stress fracture at the posteromedial aspect of the right distal tibia. Bilateral shin splints were also present.
Stress fractures are commonly seen in young athletes. When they are not treated, they can have devastating consequences. The reported incidence of stress fractures ranges from 1-20% of sports injuries. Stress fractures are much more common in the lower extremities due to weight bearing activities. A review of 350 athletes concluded that the tibia was the most common sites for stress fractures (49.1%), followed by the tarsals (25.3%) and the metatarsals (8.8%). Stress fractures of the upper extremities are rare, but do occur. There is some evidence to suggest that there is a sex predilection for stress fractures with females being more at risk than males.
Stress fractures occur when a bone breaks after being subjected to repeated tensile or compressive stresses. When placed under mechanical stress, bone remodels. The rate of remodeling depends on the frequency of loading cycles the bone is subject to. When there is a sudden increase in the duration, intensity or frequency of physical activity without rest may lead to an imbalance between bone resorption and formation. An abrupt increase in the duration, intensity, or frequency of physical activity without adequate periods of rest may lead to pathologic changes in bone. These pathologic changes result from an imbalance between bone resorption and formation, rendering the bone susceptible to microfractures, which may then coalesce into stress fractures.
Plain radiographs are usually normal early in the disease as they were in our patient. Advanced lesions may demonstrate periosteal reaction, new bone formation or even a distinct fracture line. According to the ACR guidelines, magnetic resonance imaging is the recommended standard for stress fracture evaluation when clinical suspicion is high and plain radiography is normal. Bone scans may also be done, however MRI is usually the recommended imaging procedure. Acute stress fractures show increased uptake on all three phases of a technetium 99m diphosphonate bone scan, as was seen in our patient.
- Young AJ, McAllister DR. Evaluation and treatment of tibial stress fractures. Clin Sports Med. 2006 Jan;25(1):117-28, [PMID: 16324978].