Stress Fracture - Shin Splints

A stress fracture is an overuse injury, one of the most common injuries in sports, especially the weight bearing bones of the lower extremities.

MRI has surpassed skeletal scintigraphy showing equal sensitivity, but a higher specificity, while providing improved anatomical detail.  However, there is still reason for obtaining a three phase bone scan for lower extremity trauma when MRI may be inconclusive or for patients who can not handle the MRI scan.

Often a physician will request a 3 phase bone scan for lower leg pain to determine if the pain in a patient's lower extremity is either a stress fracture or trauma, or shin splints (medial tibial stress syndrome).

A stress fracture often occurs as the result of an increasing amount or intensity of pressure during an activity more rapidly than the bone structure can manage. They may also be caused by impact (rapid change in surface hardness), improper equipment (poor foot support in a shoe) and increased physical stress.1

The stress fracture is  a small crack in the bone without displacement. The associated symptom is pain, which subsides with rest.

Delayed skeletal images of a young jogger complaining of lower extremity pain while running. Top images show lateral and medial images, white the lower images show anterior and posterior images of the lower extremities. all views demonstrate a focal area of uptake in the left tibia, consistent with a stress fracture. The area correlated with the patient's focus of pain.

On a 3 phase bone scan the dynamic flow with have increased uptake at the site of injury. The second phase (blood pool, soft tissue) will also have increased uptake associated with edema around the injured site.

The 3rd phase (skeletal image) will again demonstrate increased focal uptake at the site associated with the patient's pain.

The dynamic images and soft tissue phase (not shown) demonstrated no abnormal uptake or early osseous localization.

Anterior delayed image - young female athlete complaining of lower extremity pain for 6 months. MRI was inconclusive for stress fracture, but positive for a stress injury.

Right lateral and left medial image demonstrates linear uptake along the tibial shaft consistent with 

shin splints. No evidence of fracture.

The shin splint is an inflammation of the muscle, tendons and bone tissue around the tibia, usually along the inner border of the tibia where the muscle attaches to the bone. Shin splints may be the result of improper footwear, increase in workload on the lower extremities, changes in surface conditions. All the same causes as a possible stress fracture.

The patient complaint is pain, which may be associated with mild swelling, which subsides with rest.

On a 3 phase bone scan their may be some activity associated with edema on the flow or soft tissue phases. However the delayed skeletal image will not have a focal point of activity, but increased uptake seen along the tibia.

An advantage of utilizing the bone scan over MRI is the ability to image the whole body following injection. Keep in mind that patients complaining of lower extremity pain may have associated hip pain.