Fig. 2A–D.

(A) The typical pattern of failure caused by a periprosthetic fracture associated with superficial dome-shaped ON after a hip resurfacing arthroplasty is characterized by yellowish bone tissue without vital reaction. (B) A corresponding contact radiograph illustrates the absence of lytic or sclerotic changes. (C) A similar ON lesion with adjacent elastic brownish fibrosis reveals (D) multiple small collapsed bone fragments in the fibrosis in a hip revised for loosening of the femoral component.