Progressive bone resorption after pathological fracture of the femoral neck in Hunter's syndrome.

We report a case of Hunter's syndrome associated with a transverse fracture of the left femoral neck after minor trauma, followed by progressive resorption of the femoral head at 12 years of age and a stress fracture of the right femoral neck at 16 years of age. MRI performed at 15 years of age revealed intra-articular low intensity on T1-weighted and T2-weighted images of both hip joints. The MR finding may represent fibrous synovial thickening, which caused pressure erosion of the femoral neck, resultant pathological and/or stress fractures, and subsequent osteonecrosis with rapid absorption of the femoral head.