Perthes' Disease - Causes

What causes Perthes' disease?

Cross-section diagram of the pelvis and hips
Diagram detailing the hip joint

Perthes' disease occurs in a part of the hip joint called the femoral head. This is the rounded top of the thigh bone (femur) which sits inside the hip socket (acetabulum). Something happens to the small blood vessels which supply the femoral head with blood. So, parts of the femoral head lose their blood supply. As a result, the bone cells in the affected area die, the bone softens and the bone can fracture or become distorted. The amount of bone damage can vary from mild to severe.

The exact cause of the blood vessel problem that occurs in the first place is not known. A child with Perthes' disease is usually otherwise well.

Over several months the blood vessels regrow, and the blood supply returns to the bone tissue. New bone tissue is then made so the femoral head reforms and regrows. This is similar to how bone reforms and regrows after any normal fracture or break to a bone. But, with Perthes' disease, it takes longer (often between two and three years).

The main concern with regrowth of the femoral head is to ensure that it forms a good rounded (spherical) shape. This helps it to fit well into the hip joint socket. If the femoral head is less rounded, hip movements may continue to be affected after the blood vessels have regrown and there may be more wear and tear on the hip joint.

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Author:
Dr Colin Tidy
Peer Reviewer:
Dr John Cox
Document ID:
4842 (v42)
Last Checked:
08 July 2017
Next Review:
07 July 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.