A bunion is a three-dimensional deformity, but standard weight-bearing X-rays remain a central part of assessment. Common views include an anteroposterior view from above, an oblique view and a side view. Together they help show the degree of deviation, the condition of the big-toe joint, sesamoid position and other problems across the forefoot.
Loading matters because the alignment of the first metatarsal and big toe can change when body weight passes through the foot. Research has shown that treatment decisions can differ when weight-bearing and non-weight-bearing radiographs are compared. For that reason, images taken while standing are generally preferred for a symptomatic bunion, particularly when an operation is being planned.
X-rays can show whether the first metatarsophalangeal joint remains congruent, whether arthritis is present and whether the sesamoid bones beneath the metatarsal head are displaced relative to the first metatarsal. They can also identify metatarsal length patterns, lesser-toe deformity, previous injury or other sources of forefoot pain.
Radiographs are not interpreted in isolation. A large angle does not automatically mean surgery is needed, and a relatively modest deformity can still be very painful. Imaging findings must be considered alongside the clinical examination, symptoms, footwear needs, work and activity goals.
Routine MRI is generally not required to diagnose an uncomplicated bunion. Additional imaging may be useful when another condition is suspected, but the decision depends on the clinical question rather than on a desire to obtain every possible scan.