Nonanatomical Reduction of Femoral Neck Fractures in Young Patients (≤65 Years Old) with Internal Fixation Using Three Parallel Cannulated Screws

Abstract

Purpose: The study is aimed at investigating the association between different reduction classifications (anatomic reduction, positive buttress position reduction, and negative buttress position reduction) and two end points (complications and reoperations).

Methods: The study retrospectively analyzed 110 patients undergoing internal fixation with three parallel cannulated screws from January 2012 to January 2019 in Huashan Hospital. Based on the principles of the "Gotfried reduction," all enrolled patients were divided into three groups: anatomic reduction, positive buttress position reduction, and negative buttress position reduction intraoperatively or immediately after surgery. Clinical characteristics including age, sex, side, Garden classification, Pauwels classification, fracture level, reduction classification, Garden alignment index angles, cortical thickness index (CTI), tip-caput distance (TCD), angle of the inferior screw, and the two ending points (complications and reoperations) were included in the statistical analysis. The Mann-Whitney U-test, the chi-square test, Fisher's exact test, and multiple logistic regression analysis were used in the study.

Results: Of the 110 patients included in our study, the mean ± standard deviation (SD) of age was 51.4 ± 10.4 years; 41 patients showed anatomic reduction, 35 patients showed positive buttress position reduction, and 34 patients showed negative buttress position reduction. For the outcomes, 24 patients (anatomic reduction: 6 [14.6%]; positive buttress position reduction: 5 [14.3%]; negative buttress position reduction: 13 [38.2%]) had complications, while 18 patients (anatomic reduction: 5 [12.2%]; positive buttress position reduction: 3 [8.6%]; negative buttress position reduction: 10 [29.4%]) underwent reoperations after surgery. In the multivariate logistic regression analysis of complications, negative buttress position reduction (negative buttress position reduction vs. anatomic reduction, OR = 4.309, 95%CI = 1.137 to 16.322, and p = 0.032) was found to be correlated with higher risk of complications. The same variable (negative buttress position reduction vs. anatomic reduction, OR = 5.744, 95%CI = 1.177 to 28.042, and p = 0.031) was also identified as risk factor in the multivariate logistic regression analysis of reoperations. However, no significant difference between positive reduction and anatomical reduction was investigated in the analysis of risk factors for complications, not reoperations.

Conclusion: Positive buttress position reduction of femoral neck fractures in young patients showed a similar incidence of complications and reoperations compared with those of anatomic reduction. For irreversible femoral neck fractures, if positive buttress position reduction has been achieved intraoperatively, it is not necessary to pursue anatomical reduction; however, negative reduction needs to be avoided.

Figure 1

A pattern diagram showing (a, d) anatomic reduction, (b, e) positive buttress position reduction, and (c, f) negative buttress position reduction on AP radiograph. In positive buttress position reduction, the distal fracture segment is located inferiorly-medially to the lower-lateral part of the proximal fracture segment on AP radiographs. In negative buttress position reduction, the distal fracture segment was located superiorly-medially to lower-lateral part of the proximal fracture segment on AP radiographs.

Figure 2

Follow-up of a female patient (49 years old) with anatomic reduction (a–f). (a) Presurgery. (b) Immediately after surgery: anatomic reduction (blue arrow). (c–f) 6 months, 9 months, 2 years, and 5 years after surgery: no complication occurred.

Figure 3

Follow-up of a female patient (36 years old) with positive buttress position reduction (a–f). (a) Presurgery. (b, c) Intraoperatively and immediately after surgery: positive buttress position reduction (blue arrow). (d–f) 6 months, 1 year, and 5 years after surgery: no complication occurred.

Figure 4

Follow-up of a female patient (51 years old) with negative buttress position reduction (a–f). (a) Presurgery. (b) Immediately after surgery: negative buttress position reduction (blue arrow). (c) 6 months after surgery: nonunion remained and perforation occurred. (d) 15 months after surgery: fracture healed, while perforation remained. (e) 2 years after surgery: avascular necrosis of the femoral head (AVN) occurred. (f) 2 years after surgery: total hip arthroplasty (THA) was performed.

Figure 5

A pattern diagram of different radiographic measurements (a, b). (a) A-B and C-D: the tip-cartilage distance of each screw; E-F: the diameter of screw, used for the calibration of measurements; G-H-I: angle of inferior screw, the angle between the lateral cortex of the femoral shaft and the inferior screw. (b) Cortical thickness index (CTI) = (distance (J − K)–distance (L − M))/distance (J − K). CTI is defined as the ratio of the thickness of the cortical bone to the diameter of the femoral shaft 10 cm below the tip of trochanter minor.

Figure 6

Distribution of (a) complications and (b) reoperations in different reduction methods. (a) The percentage of complications in anatomic reduction, positive buttress position reduction, and negative buttress position reduction was 14.6%, 14.3%, and 38.2%. (b) The percentage of reoperations in the three reduction methods was 12.2%, 8.6%, and 29.4%.