What is the cause of increased radiopacity on one cortex of the tibia in a healthy 15-year-old male?

From the Guidelines

An increase in radiopacity on one cortical side of the tibia in a healthy 15-year-old male is most likely a benign finding called cortical thickening or periosteal reaction, which is commonly seen in adolescents during growth spurts and is often related to normal bone remodeling or healing of minor stress injuries that occur during physical activity. This condition is often asymptomatic and does not require specific treatment, as supported by the most recent study 1. However, it is essential to monitor the patient's symptoms and follow up with imaging studies to ensure the stability of the finding.

Key Considerations

• The increased radiopacity occurs because bone responds to stress by laying down additional calcium, creating a denser appearance on X-ray, as explained in 1.
• If the patient is experiencing pain, rest from high-impact activities for 2-4 weeks, along with over-the-counter pain relievers like ibuprofen (400-600mg three times daily with food), may be helpful, as suggested in 1.
• The return-to-run criteria should be individualized based on the risk and grade of the tibial bone stress injury, as well as the level of the athlete, as recommended in 1.
• Functional progression and assessment of lower extremity strength are crucial in determining the readiness to return to running, as highlighted in 1.

Recommendations

• A follow-up X-ray in 3-6 months to ensure stability of the finding is recommended.
• If the patient is experiencing pain, rest and over-the-counter pain relievers may be helpful.
• Further evaluation by an orthopedic specialist is warranted if the radiopacity increases significantly on follow-up imaging, or if pain develops or worsens, to rule out other conditions such as osteoid osteoma or early osteosarcoma, as mentioned in 1.

From the Research

Possible Causes of Increased Radiopacity

• Non-ossifying fibromas (NOF) are a benign entity of the developing bone, relatively common in children and young adults, and their location is most frequently metaphyseal 2.
• NOFs are usually asymptomatic unless associated with a fracture and have a self-limited behavior, with spontaneous regression through a sclerotic consolidation 2.
• A study found that stage B lesions of NOFs were at an increased risk of fracture, and the age range over which fractures occur was wide 3.

Characteristics of Non-Ossifying Fibromas

• NOFs most frequently affect the long bones of the lower extremity, and most lesions are detected incidentally 3.
• A 4-point criteria was created to calculate fracture risk for distal tibia and distal femur NOFs, which included factors such as width on coronal and sagittal views, cortical breach, and lack of a neocortex 4.
• The analysis of CT scans found that lesions with higher scores were at a greater risk of fracture, with 100% of lesions with a 4-point score fracturing 4.

Diagnostic Imaging

• Plain X-ray is the main imaging tool for the diagnosis of NOFs, but an unclear X-ray may lead to further imaging studies such as CT scans or MRI evaluations 2, 4.
• CT scans can be used to assess the size and location of NOFs, as well as the presence of any cortical breach or lack of a neocortex 4.