The value of magnetic resonance imaging in investigating a painful total knee arthroplasty.

This case describes a rare cause of pain around a total knee arthroplasty and highlights the importance of a structured approach to the investigation of these patients. Magnetic resonance imaging provided detailed information about the cause of pain despite the presence of a prosthetic joint, and the pathology, primary non-Hodgkin lymphoma, was treated without the need for further surgical intervention.