To determine the value of bone scintigraphy in predicting avascular necrosis following femoral neck fracture, and to analyze of relationship between pintract sign (increased radioactivity along the pins) and avascular necrosis after multiple pinning of femoral neck fracture.

We analyzed 20 femoral neck fractures, which were fixed with cannulated screws(14 cases) or Knowles pins(6 cases). The follow-up period was longer than 18 months, and bone scintigraphy was carried out at postoperative 3 weeks, 3 months interval to 1 year, 6 months interval to 2 years, and then every 1 year.

There were 14 cases with positive pin-tract sign and increased uptake of femoral head on bone scintigraphy performed at the postoperative 3 weeks, and I case with positive pin-tract sign and partially decreased uptake of femoral head. None of them developed avascular necrosis. There was I case with negative pin-tract sign and partially decreased uptake of femoral head, which showed increased uptake later and didn't develop avascular necrosis. There were 4 cases with negative pin-tract sign and generally decreased uptake of the femoral head, and all of them developed avascular necrosis.

Bone scintigraphy is a useful method predicting the avascular necrosis following femoral neck fracture, and pin-tract sign may be an early postoperative sign indicating that there is little possibility of development of avascular necrosis.