Less Is More for Non-Dislocated Femoral Neck Fractures: Similar Results for Two versus Three Cannulated Hip Screws

Cannulated hip screws (CHS) can be used for the minimally invasive fixation of non-dislocated femoral neck fractures. Usually, three screws are inserted. This study aims to determine whether fixation by two CHS leads to similar results as fixation by three CHS. Since January 2019, all patients with an indication for internal fixation by CHS were treated with two CHS and followed prospectively. Results were compared to an equal-sized control group of patients who underwent fixation by three CHS (before 2019). The primary outcome was reoperation, while the secondary outcome was screw dislocation. Since January 2019, 50 patients were treated by two CHS. Of these, 14 patients (28%) underwent reoperation versus 13 patients (26%) in the control group (p = 1.000). Reoperations included screw replacement, hemiarthroplasty, and total hip prosthesis. Three major reasons for reoperation were pain due to osteosynthesis material (n = 15), coxarthrosis (n = 4), and screw cut out (n = 3). Six weeks postoperative X-rays showed a screw dislocation of 2 mm for the two CHS group and 1 mm for the three CHS group (p = 0.330). Clinical outcomes were very similar between the groups. The overall results were good; however, the reoperation rate varied from 26 to 28%. The majority of reoperations were screw replacements. Screw dislocation seems to be more prominent in patients treated with two screws (2 mm versus 1 mm). Fixation by two cannulated hip screws is an acceptable treatment method for non-dislocated femoral neck fractures, and the insertion of a third screw does not lead to superior clinical results.