[Subtype classification of Garden III femoral neck fractures in the elderly based on frontal Garden index and its clinical significance].

OBJECTIVE: To retrospectively study postoperative Garden III femoral neck fractures in the elderly so as to explore the different degree of displacement of Garden III femoral neck fracture, and discuss the basis and clinical significance of the subtype classification. METHODS: A total of 492 patients with complete clinical data out of the 1397 patients with femoral neck fractures treated by closed reduction and internal fixation with cannulated compression screws from September 2005 to September 2010 were included in the study. Each patient's frontal Garden Index was measured. On the basis of the frontal Garden Index, these cases were divided into three types:type A, which frontal Garden Index was more than or equal to 140°, included 53 males and 84 females with an average age of(65.3±7.2) years old ranging from 60 to 75 years old; type B, more than 120°and less than 140°, included 79 males and 172 females with an average age of (67.5±3.6) years old;and type C, less than or equal to 120°, included 38 males and 66 with an average age of(68.6±5.7) years old. Aspects were followed up including complications, consequences and hip joint function. The fracture healing and femoral head necrosis were compared among three types. RESULTS: Operative incision of 492 cases was primary healing, and no infection and other complications occurred. All patients were followed up from 2 to 10 years with an average of 6.3 years, the healing of femoral neck fracture occurred in 432 cases, and the total union rate was 87.8%. Femoral head necrosis occurred in 83 cases, and the total necrosis rate of femoral head was 16.9%. The nonunion rate of type A was 6.6%, type B was 13.5%, and type C was 16.3%, there were significant differences among three types(χ²2AB=4.377, P=0.036;χ²2AC=5.872, P=0.015;χ²2BC=0.469, PBC=0.494). The necrosis rate of femoral head of group A was 8.8%, group B was 16.7%, and group C was 27.9%, there were significant differences among three groups(χ²2AB=4.704, P=0.030;χ²2AC=15.317, P=0.000;χ²2BC=5.715, P=0.017). CONCLUSIONS: It is different for the degree of displacement of Garden III femoral neck fracture in the elderly. Based on frontal Garden Index to differentiate degree of fracture displacement, Garden III femoral neck fracture would be divided into A, B and C subtypes. The prognosis of Garden III femoral neck fracture in the elderly is negatively related to its degree of displacement, which has clinical significance to make treatment plan for Garden III femoral neck fracture in the elderly.