Three-dimensional reconstruction study of the spatial displacement of femoral neck fractures

Abstract

Objective To measure the displacement parameters of the femoral head of displaced femoral neck fracture in space through three dimensional reconstruction so as to provide new ideas in diagnosing, assessing and prognosing. Methods A review of 80 patients with an average age of 71.5 years old (range, 39-80 years; 36 males, 44 females) who suffered displaced femoral neck fractures from June 2013 to June 2014 were included in our study. Bilateral proximal femurs of displaced femoral neck fractures contains 40 Garden type Ⅲ and 40 Garden type Ⅳ were scanned by spiral CT preoperatively. Through reconstructing these primitive CT data by the Mimics software, the affected leg mirror model generated and repositioned base on the normal femur, then a new mask was created on the registered mirror model in the CT cross-sectional images, marked key points in the masks and measured the displacement parameters of femoral head with three dimensional measurement tools automatically. Results In the displaced femoral neck fractures, the femoral head displacement angle was 29.18°±15.74° in Garden type III and 39.08°±17.08° in Garden type IV. The average displacement distance of femoral head center were 14.36±5.61 mm and 18.77±5.45 mm, respectively. The average displacement distance of the deepest point of fovea capitals of femoral head were 23.70±10.00 mm compare with 30.24±8.96 mm. Conclusion A high proportion of the displaced femoral neck fractures have a large of displacement in the three dimensional space. Currently Garden's Classification exists certain limitation and incredibility in recognizing severity of the displaced femoral neck fractures. Three-dimensional reconstruction and spatial measurement technology can be more scientific and accurate in evaluating the degree of displacement of the femoral head. Our study could inspire and broaden clinicians' insights including diagnose fracture type, assess the degree of damage, establish a more rational and safe surgery plan and determine postoperative prognosis. Key words: Femoral neck fractures; Imaging, three-dimensional; Photogrammetry