What muscle was damaged in Gregory House’s leg before House M.D. begins?

Gregory House’s quadriceps muscle was damaged before House M.D. begins. A muscle infarction deprived part of his thigh muscle of blood, leading to permanent damage, chronic pain, and the limp for which the character is known.

House’s leg history is revealed gradually rather than explained in full during the opening episode. He initially receives treatment that leaves him with severe disability, and later undergoes surgery that removes dead muscle. The resulting pain contributes to his dependence on Vicodin and influences many of his personal and professional decisions.

The quadriceps is the large muscle group at the front of the thigh. Because the story involves an infarction, viewers sometimes remember the condition as a problem with the bone, knee, or heart. Those are different structures and do not identify the specific muscle described in the series.

House’s cane and limp are therefore not simply character decoration. They are visible consequences of the quadriceps injury that forms a major part of his backstory and explains his chronic pain.