A patient presents with shoulder pain after an injury; what is the best first-line imaging study to assess the shoulder?

The best first-line imaging study to assess shoulder pain after an injury is an X-ray. X-rays are the initial imaging modality used in this scenario because they are effective in identifying fractures, dislocations, and any bony abnormalities in the shoulder. They provide a quick assessment of the shoulder joint and surrounding structures, which is essential following an injury.

Using X-rays first allows healthcare providers to rule out any significant skeletal injuries that may require immediate intervention. If the X-ray reveals no fractures or bony pathology, and if the patient continues to have symptoms, further imaging like an MRI or CT scan may be warranted to assess soft tissue injuries such as rotator cuff tears or labral injuries.

In contrast, while CT scans and MRIs provide detailed views of bony and soft tissue structures respectively, they are not typically used as initial studies in acute shoulder injuries. CT scans are more often reserved for complex fractures when further evaluation is needed, whereas MRIs are beneficial for soft tissue assessment but can be more time-consuming and expensive as an initial step. Ultrasound can be useful for certain soft tissue evaluations and guided injections but is not the standard first-line study for acute injuries of the shoulder.