Idiopathic aseptic necrosis of pelvis

This code describes the spontaneous death of bone tissue in the pelvis due to a lack of blood supply, without an identifiable cause such as trauma, infection, or steroid use. This condition, also known as avascular necrosis or osteonecrosis, leads to bone collapse and joint destruction if left untreated. It specifically refers to cases where the etiology is unknown.

Use this code for patients diagnosed with avascular necrosis affecting the pelvic bones (e.g., ilium, ischium, pubis) where no underlying cause can be identified after thorough investigation. Documentation should clearly state "idiopathic avascular necrosis of the pelvis" or "aseptic necrosis of the pelvis, idiopathic." This code is appropriate when imaging studies (MRI, X-ray) confirm the diagnosis and clinical workup excludes secondary causes.

• Ensure the documentation explicitly states "idiopathic" or "aseptic" and specifies the pelvis as the affected site.
• Distinguish from avascular necrosis due to known causes (e.g., steroid-induced, post-traumatic), which are coded elsewhere.
• Code any associated pain or functional limitations separately, if documented, using appropriate symptom codes.