Comparison of the Effect of Rhombic and Inverted Triangle Configurations of Cannulated Screws on Internal Fixation of Nondisplaced Femoral Neck Fractures in Elderly Patients

Objective To investigate whether four-screw fixation in rhombic configuration could improve the clinical outcomes and decrease the complication rate compared with three-screw fixation in inverted triangle configuration in elderly patients with nondisplaced femoral neck fractures. Method From January 2018 to January 2019, 91 elderly patients with nondisplaced femoral neck fractures who were treated with a cannulated screw system were reviewed retrospectively. The inverted triangle configuration was applied in 51 patients and rhombic configuration in 40 patients. The demographic and perioperative information of the patients were extracted from medical records and surgical records. Variables including incision size, surgical blood loss, surgical time, fluoroscopy time, hospital stays, fracture union time, postoperative visual analogue scale (VAS) scores, and complications were compared between the two groups. Also, Harris hip score at the final follow-up was used to evaluate the functional outcomes. Results All patients were followed up from 24 to 36 months, with an average of 29.75 months. The average age of patients was 72.37 +/- 7.16 years. No significant differences were found between the two groups with regard to patients' age, gender, affected side, Garden classification, Pauwels classification and comminution of posterior wall (P > 0.05). We found shorter incision size (P < 0.001), less blood loss (P = 0.020), less surgical time (P = 0.026), and shorter fluoroscopy time (P < 0.001) in inverted triangle configuration group. However, shorter hospital stays (P = 0.001) and fracture union time (P = 0.002) were found in the rhombic configuration group. The VAS scores were lower in the rhombic configuration group at the first (P < 0.001) and third months (P = 0.010), but no significant difference was found at the sixth month (P = 0.075). Meanwhile, the total complication rate was relatively lower in the rhombic configuration group compared to the inverted triangle configuration group (P = 0.041). Harris hip score presented no significant difference between the two groups at final follow-up (P = 0.078). No wound infection or cortical perforation occurred in either group. Conclusion Four-screw fixation in rhombic configuration was superior to three-screw fixation in inverted triangle configuration in the treatment of nondisplaced femoral neck fractures in elderly patients in terms of less early postsurgical pain, shorter fracture union time, and lower complication rate.