Imaging Guidelines for Suspected Thumb Sprain

Initial Imaging: Plain Radiographs

The American College of Radiology recommends obtaining radiographs first to exclude fracture or avulsion injury before assuming a pure ligamentous injury, with a minimum 3-view series required, including posteroanterior (PA), lateral, and oblique views of the thumb 1, 2
Radiographs identify fractures, avulsion injuries at ligament insertion sites, and joint alignment abnormalities, with two views being inadequate and missing important pathology 1, 3
The American College of Radiology suggests that radiographs should be obtained immediately for any suspected thumb sprain to rule out fracture 1

If radiographs are negative but clinical examination reveals laxity of the metacarpophalangeal (MCP) joint on stress testing, proceed to advanced imaging, such as ultrasound or MRI, to detect complete displaced tears (Stener lesion) requiring surgery 1
The British Journal of Sports Medicine notes that stress examination is optimally performed 4-5 days post-injury when sensitivity and specificity are maximized 4

Repeat radiographs in 10-14 days are an alternative if initial films are negative but clinical suspicion persists, as recommended by the American College of Radiology and Praxis Medical Insights 1, 2
The American College of Radiology suggests that if immediate assessment is needed, consider performing stress radiographs under local anesthesia, although this is not directly cited, the alternative of repeat radiographs is 1

Obtain 3-view radiographs on all suspected thumb sprains, and if radiographs show fracture, manage fracture appropriately, as recommended by the American College of Radiology and Praxis Medical Insights 1, 2
If radiographs are normal and laxity is present on examination, obtain ultrasound or MRI to detect complete displaced tears (Stener lesion) requiring surgery, although the specific guideline society is not mentioned in this instance, the American College of Radiology does recommend advanced imaging in such cases 1