The ideal treatment of the unstable slipped upper femoral epiphysis (SUFE) is not clearly defined in the literature. Unstable SUFE occurs with less frequency than the stable SUFE. The incidence of unstable SUFE is between 14–25% of all SUFE’s. The literature reports a variety of accepted methods of treatment of the unstable SUFE, consequently, in Auckland there are various methods of treatment. The unstable SUFE is at risk of development of avascular necrosis (AVN) of the femoral head. The reported incidence of AVN in unstable SUFE is between 15–50%. We expect that different treatment will influence the rate of AVN. Our aim was to determine current practice and outcomes in Auckland. We reviewed the records and radiographs of all SUFE’s treated in Auckland from 2000–2007. In this time period there were 463 patients across the Auckland region, 109 of which had bilateral SUFE’s which allowed 572 treated hips to be followed. Over this time period there were 34 unstable SUFE representing 6% of treated hips. There was a difference in average weight, with unstable SUFE on average 10kgs lighter (60.5 vs 70.3kgs). Average time to surgery was 43 hours (range: 4–360hrs). Cases operated within 24 hours have a reduced rate of AVN (20%) compared to those operated after 24 hours (AVN 50%). Of the 34 cases, 13 cases had radiological evidence of AVN (35%). Of these there were 11 cases of pin penetration requiring further surgery. There was no difference in rate of AVN when comparing single screw to double screw fixation (SS 44% v DS 38%). There were 11 cases of pin penetration, 8 with single screw and 3 with double screw fixation. Our review of unstable SUFE in Auckland has shown a difference in the weight of patients when compared to stable SUFE’s presenting from the same population. We have also found that cases operated on within 24 hours have a lower rate of AVN. Single screw fixation is more common than double screw fixation. There was no statistical difference in the rate of AVN but there was a higher rate of screw penetration when using a single screw fixation.
