Combined Deflection Angle Classification: A Novel Typing System of Adult Femoral Neck Fracture

OBJECTIVE: Femoral neck fracture (FNF) is a common clinical trauma with high mortality and disability rates. Furthermore, its incidence increases exponentially with increasing age. Existing classifications have some disadvantages. Thus, this study aimed to establish a novel typing system for FNF. METHODS: We retrospectively analyzed all adult patients with FNF admitted to our hospital between December 2015 and November 2017 for cannulated screw internal fixation. The study population was divided into the femoral varus offset group (VAR) and the valgus offset group (VAL). The data collected included sex, age, affected side, injury mode, body mass index, complications, pelvic incidence (PI), hip deflection angle (HDA), combined deflection angle (CDA), and neck shaft angle. Statistical analysis was conducted to determine the correlation between complications and deviation angles. A novel typing system was developed and compared with the Garden classification to detect its superiority. RESULTS: A total of 108 patients were recruited, with 59 patients in the VAR and 49 patients in the VAL groups. The incidence of complications in the VAR group was significantly higher than that in the VAL group (P < 0.05). Moreover, there were more male participants in the VAR group. Compared with the VAL group, the VAR group had significantly higher PI, HDA, and CDA (P < 0.05). The CDA classification (CDAC) was defined, with CDA as the main criterion and HDA as the supplementary criterion. Furthermore, there was a hierarchical correlation between the actual incidence of complications and the typing level, which was increased in CDAC but not in the Garden classification. This showed that CDAC was more accurate. CONCLUSION: A novel typing system, CDAC, for FNF was established, which was more accurate than the Garden classification. We suggest combining CDAC and Garden classifications for the preoperative diagnosis, treatment selection, and prognostic evaluation for patients with FNF.