Is new always better: comparison of the femoral neck system and the dynamic hip screw in the treatment of femoral neck fractures

Abstract

Background Hip fractures in the elderly population are common and the number of patients is rising. For young and geriatric patients with undisplaced fractures osteosynthesis is the primary type of treatment. The dynamic hip screw (DHS) is around for many years and proved its value especially in displaced fractures. Since 2018 the femoral neck system (FNS) is available as an alternative showing promising biomechanical results. The aim of this study is to evaluate clinical results of the FNS and compare it to the DHS. Materials and methods Patients older than 18 years with Garden I–IV fractures that were treated with osteosynthesis in a level 1 trauma center were included in the study. Between January 2015 and March 2021, all patients treated with FNS (1-hole plate, DePuy-Synthes, Zuchwil, Switzerland) or DHS (2-hole plate, DePuy-Synthes, Zuchwil, Switzerland) for proximal femur fractures were included in the study. Closed reduction was achieved using a traction table. All operations were carried out by experienced orthopedic trauma surgeons. Primary outcome measures were rate of implant failure (cut out) and surgical complications (hematoma, infection). Secondary outcome measures were Hb-difference, length of hospital stay and mortality. Results Overall, 221 patients were included in the study. 113 were treated with FNS, 108 with DHS. Mean age was 69 ± 14 years. There were 17.2% Garden I, 47.5% Garden II, 26.7% Garden III and 8.6% Garden IV fractures. No difference between the groups for age, body mass index (BMI), Charlson comorbidity index (CCI), time to surgery, Pauwels and Garden classification, rate of optimal blade position or tip apex distance was found. FNS showed lower pre- to postoperative Hb-difference (1.4 ± 1.1 g/l vs. 2.1 ± 1.4 g/l; p < 0.05), shorter operating time (36.3 ± 11.6 min vs. 54.7 ± 17.4 min; p < 0.05) and hospital stay (8.8 ± 4.3 d vs. 11.2 ± 6.8 d; p < 0.05). Surgical complications (FNS 13.3% vs. DHS 18.4%, p > 0.05), rate of cut out (FNS 12.4% vs. DHS 10.2%, p > 0.05) and mortality (FNS 3.5%; DHS 0.9%; p > 0.05) showed no difference between the groups. Logistic regression showed that poor blade position was the only significant predictor for cut out and increased the risk by factor 7. Implant related infection (n = 3) and hematoma/seroma (n = 6) that needed revision was only seen in DHS group. Conclusion FNS proved to be as reliable as DHS in all patients with hip fractures. Not the type of implant but blade positioning is still key to prevent implant failure. Still due to minimal invasive approach implant related infections and postoperative hematomas might have been prevented using the FNS.

Treatment of Femoral Neck Fractures in the Elderly: A Survey of the Korean Hip Society Surgeons

“…However, along with the recent introduction of FNS to the market, almost half of the respondents answered that FNS was the device of choice for use in performance of internal fixation. When making a smaller incision, FNS appeared to provide biomechanical properties similar to those of sliding hip screws 8) . However, owing to its intuitive and straightforward approach, multiple screw fixation was selected as the device of choice among KHS members.…”

Clinical efficacy of Femoral Neck System for treatment of unstable femoral neck fractures in young adults

“…Schuetze et al. 15 assessed the clinical outcomes of the FNS versus the DHS in treating Garden grade I–IV fractures, highlighting quicker implantation and reduced blood loss with the FNS. Stassen et al.…”

Comparative Short-Term Outcomes of Femoral Neck System (FNS) and Cannulated Screw Fixation in Patients with Femoral Neck Fractures: A Multicenter Study

“… 29) Some studies have reported early full weight-bearing after FNS fixation, while others have reported that early ambulation before 6 weeks postoperatively is a risk factor for failure after FNS. 16 30) Our study used a sequential protocol from standing to toe-touch ambulation, gradually increasing partial weight-bearing, followed by full weight-bearing, rather than mandating full weight-bearing at a specific postoperative time point as in other studies, which may have reduced the risk of early failure of the FNS.…”