Comparative outcomes of cannulated screws, dynamic hip screws and the femoral neck system for transcervical femoral neck fractures. a retrospective cohort study

Background Internal fixation of transcervical femoral neck fractures remains associated with substantial failure and reoperation rates. The Femoral Neck System (FNS) was developed to improve rotational stability while remaining minimally invasive, but comparative data against traditional implants are limited. Hypothesis We hypothesised that fixation with the FNS would be associated with lower reoperation rates compared with CS and DHS. Patients and methods We performed a retrospective comparative cohort study of adults undergoing fixation of transcervical femoral neck fractures at two centres between 2019 and 2024, with a minimum of 12-months of outcome ascertainment. Data were collected from medical records and radiographs. Negative binomial regression evaluated time to surgery; logistic regression assessed fixation method against union, reoperation and complications, adjusted for age, Charlson Comorbidity Index, Garden classification, side and time to surgery. Results After exclusions, 207 patients were analysed (CS 27, DHS 100, FNS 80). Age (CS 54.8, DHS 66.9, FNS 68.2 years; p = 0.02) and Garden distribution (Garden I 7/27 CS, 27/100 DHS, 52/80 FNS; p < 0.001) differed between groups; adjusted analyses accounted for these differences. Reoperation occurred in 37/207 (17.9%): 10/27 (37.0%) CS, 20/100 (20.0%) DHS and 7/80 (8.8%) FNS (p = 0.004). After adjustment, CS remained associated with reoperation versus FNS (OR 5.26, 95% CI 1.53–18.13), whereas DHS did not (OR 1.85, 95% CI 0.65–5.26). Union occurred in 184/207 (88.9%), with no association with fixation method (p = 0.065). Complications occurred in 61/207 (29.5%): 11/27 (40.7%) CS, 32/100 (32.0%) DHS and 18/80 (22.5%) FNS (p = 0.15); higher Garden classification was associated with more complications (Garden II OR 2.58, Garden III OR 3.44; p = 0.037). Time to surgery was shorter with DHS than FNS (IRR 0.49, 95% CI 0.35–0.69; p < 0.001), although the median was 1 day in all groups. Avascular necrosis occurred in 4/80 (5.0%) FNS, 11/100 (11.0%) DHS and 2/27 (7.4%) CS (p = 0.42). Discussion Union rates were high across fixation methods. FNS was associated with lower reoperation rates than CS and similar adjusted outcomes to DHS. Prospective studies with patient-reported outcomes are required to confirm these findings. Level of evidence III; Retrospective cohort study.