What a Knee MRI Shows That an X-Ray Cannot

A Seoul orthopedic surgeon explains why an MRI often comes before any decision about knee surgery — and how faster scans and same-day reading change the visit

SEOUL, South Korea - For most people with knee pain, the first test is an X-ray. It is quick, widely available and good at showing how much space is left between the bones. But it leaves out much of what matters when deciding between treatments.

"An X-ray tells us how much space is left in the joint," said Yeong Seok Lee, M.D., Ph.D., an orthopedic surgeon at St. Luke's Hospital in Seoul. "An MRI tells us what is happening to the cartilage and meniscus inside it — and that is often what decides whether a joint-preserving option is worth discussing."