Introduction: The purpose of this report was to describe a very rare case of simultaneous bilateral quadriceps tendon rupture seen in a patient who was diagnosed as having diffuse idiopathic skeletal hyperostosis.
Case presentation: A man aged 64 years presented to the emergency department with bilateral quadriceps tendon rupture. Surgical repair was performed with suture anchors and a stainless steel cable. His legs were immobilized in casts for six weeks. After removal of the casts, physiotherapy was started. Four months after surgery, he was able to walk with 0°-120° range of motion and active extension. He was followed up for 8 years without rerupture or other complications.
Conclusion: Bilateral rupture of the quadriceps tendon is a rare condition and generally related to metabolic disorders. Diffuse idiopathic skeletal hyperostosis is a metabolic disorder that causes bilateral quadriceps tendon rupture, and it accounted for the differential diagnosis of the underlying condition.