What is the diagnosis?

Proximal tibial stress fracture

• Pearl: Stress fractures in runners are most common in the tibia [1].

• Pearl: It is common to not visualize a fracture line in stress injuries as they occur on a spectrum. If you do see a definitive line (the dreaded black line), this is indicative of a significant stress injury. 

What are risk factors for injury?

Risk factors for tibial stress fractures generally fall into three categories. They can be activity-related, such as a sudden increase in activity or changes in terrain or biomechanical, such as calf muscle weakness and leg-length discrepancy. Metabolic factors including bone demineralization and nutritional deficiencies can lead to stress fractures as well.

What physical exam and history findings are expected?

Unless the stress fracture is a direct result of trauma, pain is usually insidious in onset and increases with activity. Occasionally, pain may be more moderate or chronic in the setting of bone stress that finally fractures, causing sudden increase in pain. Pain should localize to a discrete area along the bone, and local swelling may be present. This helps differentiate from medial tibial stress syndrome, where tenderness along the shin is more diffuse.

• Pearl: Inability to hop on the symptomatic leg for ten consecutive hops without inducing pain is the most sensitive physical exam finding, though it should be interpreted in clinical context [2].

Which imaging modalities can be used?

Initial imaging assessment for suspicion of stress fracture is with a plain radiograph, which is a specific, but insensitive test. Symptoms may precede appearance on radiographs. If clinical suspicion is high, you may proceed with an MRI, which can detect early edematous signs of stress fractures and more subtle periosteal changes, making it a significantly more sensitive test [3]. 

• Pearl: There are several systems used to grade MRI bone stress injuries. These systems delineate severity by assessing for periosteal edema, bone marrow edema, and cortical fracture lines. While there are several different grading systems, differentiating between a low-grade and high-grade stress fracture offers prognostic value for time to return to sports [4]. 

Image 2. MRI of proximal tibia. Red arrow pointing to the black line representing the fracture with brighter surrounding bone marrow edema. Author’s own images.

What is the management in the ED?

Like most stress fractures, initial treatment for tibial stress fractures is rest and stabilization of the bone. For lower-leg fractures, you can use a long air splint, knee splint, or hinge brace. CAM walkers or cast boots can also be used. No crutches are required if the patient can ambulate with minimal pain in the splint. If they do have continued pain with splinting, they need to be made non-weight bearing. 

• Pearl: Stress fractures are also grouped into high-risk and low-risk locations, which can contribute to weight-bearing status. High load-bearing areas such as the anterior tibial diaphysis or the tension side femoral neck are considered high risk.

When do you need to consult orthopedics?

Stress fractures that reveal a severe fracture on MRI (based on radiologic grading system of fractures) requires urgent orthopedic (or sports medicine) referral within several days.

• Pearl: If there is a tension-sided femoral neck stress fracture this should specifically be referred to orthopedics urgently.