Fig. 1A–D.

(A) A sagittal MRI scan of Patient 1 shows a cyst located anterior to the hip resurfacing. During revision surgery, 80 mL of watery, brown joint fluid was collected. (B) A 6-year postoperative radiograph shows a left hip resurfacing in good position. (C) A light micrograph of periprosthetic tissue stained with hematoxylin and eosin shows a mild histiocytic infiltrate adjacent to fibrin lining the surface response (original magnification, × 40). (D) The wear map of the femoral head shows a round wear patch with a maximum wear depth of 14 μm. The wear map of the acetabular component shows a wear patch and deformation (white area) from surgical removal.