Non-union in an unnoticed neck fracture in resurfacing total hip arthroplasty.

The renewed popularity of resurfacing hip arthroplasty (RHA) in the last five years has generated a remarkable quantity of scientific contributions based on mid- and short-term follow-up. In spite of some large series with extremely low complication rates, more than one paper has reported a consistent early revision rate as a consequence of biological or biomechanical failure. Two major complications are commonly described with resurfacing implants: avascular necrosis and neck fracture. A close relationship between these two events has been suggested, but not firmly demonstrated, while surgical exposure and implant positioning seem to be better understood as potential causes of failure. However, it may happen that neither avascular necrosis nor neck fracture can be clearly recognised in a failed resurfacing implant: it is what we have directly experienced, with a missed fracture at the head-neck junction, evolved in non-union, beneath the dome of the femoral component. The present report, besides a brief clinical history, tries to give a possible interpretation of such an unusual complication.