RESUMO
<p><b>OBJECTIVE</b>To investigate the failure of internal fixation on displaced femoral neck fractures in adults under fifty-five years old retrospectively inorder to pay more attention to the treatment of these fractures.</p><p><b>METHODS</b>From Junary 2007 to June 2010,18 failed cases of internal fixation on displaced femoral neck fractures in adults under fifty-five years old were treated,there were 13 males and 5 females with an average age of (48.0 +/- 6.0) years old ranging from 27 to 55. Among them, 17 patients were treated with cannulated screws and 1 patient was treated with intramedullary nail; 16 patients were diagnosed as osteonecrosis and 2 patients as osteonecrosis associated with nonunion.</p><p><b>RESULTS</b>The average time from internal fixation to failure was 23 months (ranged, 8 to 32 months). The quality of fracture reduction in Garden index was poor. The Harris Hip Score was (56.0 +/- 12.5) (ranged,33 to 80). Eight cases of osteonecrosis and 2 cases of nonunion combinated osteonecrosis were received total hip arthroplasty. Hip resurfacing arthroplasty were performed for other 5 osteonecrosis. Because of no evident clinical symptoms,the other 3 cases received conservative treatment. The patients with total hip arthroplasty and hip resurfacing arthroplasty were followed-up for 34 months ranging from 12 to 53 months. After operation,the Harris score was (94.0 +/- 3.0) ranged 89 to 96.</p><p><b>CONCLUSION</b>Osteonecrosis is a common complication after internal fixation on displaced femoral neck fracture in adults under fifty-five years old. More attention should be paid to the treatment of displaced femoral neck fracture in those patients.</p>