Inclusion and exclusion criteria.
Inclusion criteria: (i) Patients with fresh unilateral femoral neck fracture; (ii) Patients were younger than 65 years; (iii) Pauwels type-3 femoral neck fracture; (iv) Patients did not have fractures in other sites; (v) Follow-up data were completely recorded.
Exclusion criteria: (i) Patients with excessive drinking, long-term history of hormone drugs or femoral head necrosis; (ii) Patients with other severe diseases; (iii) Patients with pathological fractures; (iv) Patients with severe cognitive dysfunction.
A retrospective analysis was made on 81 eligible femoral neck fracture patients undergoing FNS or cannulated screw fixation in the Department of Orthopedics, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital from January 2018 to December 2019. Among them, 30 patients were treated with FNS and 51 patients were treated with traditional three cannulated screws. Patients with FNS were selected as the experimental group and patients with cannulated screws were control group. A pair-matched clinical research was performed. Matching requirements were as follows： the same gender, age ± 3 years old, BMI(Body Mass Index) ± 2kg/m2. A total of 30 pairs were successfully matched at a 1:1 ratio, including 12 males and 18 females. The average age of the patients in the FNS group was 54.53±6.71 years, and the BMI was 23.24±2.12 kg/m2. In the cannulated screw group, the average age of the patients was 53.14±7.19 years, and the BMI was 22.73±2.13 kg/m2. No significant differences were identified in their preoperative baseline characteristics.
Femoral neck fracture surgery was conducted within 48 h of admission by the same group of surgeons. Patients received to spinal anesthesia and fixed in a supine position. The operated limb was placed on the traction frame in an abducted, internally rotated position. Postoperative reduction was observed using C-arm localization.
For patients received to FNS, a longitudinal incision was cut on the lateral hip to expose the proximal femur. A Kirschner wire was inserted in the femoral head alongside the lateral femur to temporarily fixed the femoral neck fracture with a satisfactory reduction. Under the guidance of a localizer at 130°, a Kirschner pin was inserted in the femoral neck, which was placed in the central of both femoral neck and femoral head in the anteroposterior view. FNS (DePuy Synthes Products, USA) was instrumented in after reaming and sounding. A locking screw was placed in the distal hole and rotated in the femoral neck, and then the temporarily fixed Kirschner pin was pulled out.
For patients received to cannulated screw fixation, a Kirschner wire was inserted diagonally upward in the cortical bone 5 cm, 7 cm and 9 cm distal to the apex of the greater trochanter of femur, respectively. They were placed in the central of the femoral neck and the femoral head, as well as 1 cm below the articular surface of the femoral head in a shape of triangle. A 1 cm incision was cut at the tip of the Kirschner pin. After exposing the lateral cortical bone, a hole was drifted till to the fracture end. An appropriate cannulated screw was rotated in under the guidance of the Kirschner wire, which was localized by X-ray. The Kirschner wire was finally pulled out.
Postoperative multimodal analgesia and anti-coagulation using rivaroxaban were performed. Patients were encouraged to start excise within 24 h postoperatively. By the 2nd week postoperatively, patients started to ground exercise with the help of crutches, and weight-bearing on the affected limb was forbidden. Partial weight-bearing exercise was encouraged at 6th week and recovered to normal exercise based on the patient’s condition, then walked without crutches. The patients were followed up at 1, 3, 6, 9 and 12 months after operation. Typical cases received to FNS and cannulated screw fixation were depicted in Figure 2 and Figure 3, respectively.
Quality of fracture reduction was assessed based on quantitative indicators proposed by Haidukewych et al.as the follows: (i) An excellent reduction: Displacement after reduction < 2 mm and deformity angle at any plane < 5°; (ii) A fair reduction: Displacement after reduction ranged 6-10 mm and deformity angle at any plane ranged 11-20°; (iii) A poor reduction: Displacement after reduction > 10 mm and deformity angle at any plane > 20°. Operation time, intraoperative blood loss, 1st day postoperative VAS(Visual Analogue Scale) score, hospital stay, hospitalization cost, time walking without crutches, Harris score, complication rate and femoral head necrosis rate were recorded. Complications included bone nonunion, loss of reduction, and loosening of internal fixation.
SPSS 25.0 was used for statistical analysis. Data were expressed as Age, BMI, operation time, intraoperative blood loss, length of stay, hospital stay, hospitalization cost, 1st day postoperative VAS score, time walking without crutches, and Harris score were compared by the Student’s t test. Gender, postoperative reduction, femoral head necrosis rate and complication rate were compared by the c² test or Fisher’s exact test. P<0.05 was considered as statistically significant.