Femoral neck fractures represent a significant orthopedic issue, accounting for approximately 53% of all hip fractures (1). Due to the distinct anatomical and biomechanical properties of the femoral neck, conservative treatment poses considerable risks of femoral head necrosis, establishing surgical intervention as the standard approach (2). While hip arthroplasty is typically favored in patients aged 65 years and older due to its potential for facilitating rapid functional recovery, internal fixation remains the preferred approach in younger patients, given the limited lifespan of prosthetic implants. The choice of the most appropriate internal fixation method remains a subject of ongoing debate. Current clinical practice employs a variety of techniques, including cannulated compression screws (CCSs), femoral neck systems (FNSs), dynamic hip screws, locking plates, and intramedullary nails. Among these, the CCS approach has been the predominant choice, while the FNS was initially introduced in China in 2019 (3). Although both the FNS and CCSs have demonstrated clinical efficacy in treating femoral neck fractures, existing studies present conflicting results concerning operative duration, fracture healing time, final Harris hip scores, and postoperative complications, such as femoral head necrosis, wound infection, delayed union, non-union, and femoral neck shortening (4–8). This systematic evidence synthesis seeks to compare CCS and FNS through a meta-analysis of contemporary clinical studies, thereby providing clinicians with updated guidance for surgical decision-making.

A comprehensive literature search was conducted utilizing the following search terms: “femoral neck fractures,” “Femoral Neck Fractures,” “Femoral Neck Fracture,” “Femur Neck Fractures,” and “Femur Neck Fracture,” in conjunction with “hollow screw,” “cannulated screws,” “hollow bolt,” and “cannulated screw,” as well as “Femoral Neck System” or “femoral neck screw system.” This search was performed across several databases, including the Cochrane Library, PubMed, Web of Science, and Embase, covering the period from the inception of each database to 6 August 2024. The search strategy did not intentionally exclude studies published in languages other than English. The detailed search methodology is depicted in Figure 1.

The precise search strategy employed was: (Femoral Neck System) OR (Femoral Neck System) OR (FNS) AND (cannulated screw) OR (cannulated screws) OR (hollow screw) OR (cannulated compression screw) AND (Femoral Neck System) OR (Femoral Neck System) OR (FNS).

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, the literature screening process was conducted in four distinct stages. Initially, 953 studies were identified through database searches. After removing duplicates, 643 progressed to the screening stage. Of these, 589 were excluded after reviewing titles and abstracts that did not meet the inclusion criteria. The remaining 54 studies were subjected to an eligibility assessment. Following a comprehensive full-text evaluation, 45 studies were excluded—2 due to inconsistent observational metrics and 43 because they included patients older than 65 years. Consequently, nine high-quality cohort studies were selected for inclusion in the meta-analysis.

The data were analyzed utilizing RevMan 5.4 software. Heterogeneity among the included studies was evaluated using the Q-test with a significance level of α = 0.1. In addition, the I² statistic was used to quantitatively assess the degree of heterogeneity. A fixed-effects model was employed for the meta-analysis when P > 0.1 or I² < 50%, indicating low heterogeneity. Conversely, when P ≤ 0.1 or I² ≥ 50%, high heterogeneity was inferred, prompting further analysis to identify its sources. Following the exclusion of evident clinical heterogeneity, a random-effects model was applied for the meta-analysis. The significance level (α) was set at 0.05. In cases of significant clinical heterogeneity, subgroup or sensitivity analyses were conducted. If these analyses were not feasible, a descriptive analysis was performed. For continuous variables, the weighted mean difference (WMD) or standardized mean difference (SMD) was used as the pooled statistic, while for dichotomous variables, the risk ratio (RR) was employed.

This meta-analysis provides substantial clinical insights from a comparative evaluation of the femoral neck system (FNS) and cannulated compression screw (CCS) techniques in the management of femoral neck fractures among young adults. The results indicate that the FNS outperforms CCS across various intraoperative and postoperative parameters, offering valuable guidance for clinical practice. Notably, the FNS group exhibited a significantly reduced frequency of intraoperative fluoroscopy sessions compared to the CCS group (MD = −8.14, 95% CI: −9.82 to −6.46, P < 0.001). This decrease in fluoroscopy usage can be attributed to the streamlined design of the FNS, which incorporates a single sliding screw and an anti-rotation side plate. Conversely, the CCS approach necessitates the use of multiple screws, complicating the positioning and fixation process. Consequently, surgeons can achieve precise screw placement more efficiently with the FNS, thereby diminishing reliance on fluoroscopic guidance (21). Furthermore, the design of the FNS is more compatible with the anatomical configuration of the proximal femur and femoral neck, requiring fewer adjustments in fluoroscopy angles and positioning compared to the CCS (22). In the context of fracture healing, the FNS group demonstrated a significantly shorter healing duration than the CCS group (SMD = 16.30, 95% CI: 3.79–28.82, P < 0.001). This advantage is primarily attributed to the biomechanical design of the FNS system, which integrates a single slip screw with an anti-rotation side plate. This configuration effectively minimizes rotational stress and shear forces, promoting more stable fixation, reducing fretting at the fracture site, mitigating inflammatory responses, and enhancing the overall healing process (23). At the final follow-up, the Harris score for hip function was significantly higher in the FNS group than in the CCS group (WMD = −3.43, 95% CI: −4.08 to −2.77, P < 0.001). This finding underscores the superior recovery of hip function associated with the FNS, which effectively maintains fracture alignment and provides stronger anchorage than hollow screws. Patients treated with the femoral neck system (FNS) are able to bear weight and mobilize earlier, which contributes to a reduced incidence of postoperative complications such as screw loosening and bone non-union. These factors are essential for achieving stable functional recovery of the hip joint. In addition, the streamlined pain management and rehabilitation processes associated with the FNS lead to improved functional outcomes during follow-up evaluations. The incidence of postoperative complications, including femoral head necrosis, incision infections, delayed union, fracture non-union, femoral neck shortening, and thigh pain, was significantly lower in the FNS group than in the cannulated compression screw (CCS) group [RR = 0.35, 95% CI: 0.23–0.53, P < 0.001]. The distinctive fixation method employed by the FNS facilitates uniform stress distribution, thereby reducing the risks of screw loosening and fracture displacement (24). This mechanical stability is vital for decreasing the incidence of bone non-union and femoral head necrosis. Furthermore, enhanced biomechanical stability diminishes the likelihood of postoperative local inflammation and osteonecrosis, resulting in a lower overall complication rate among patients (20). However, despite its advantages, the FNS is associated with a significantly longer incision (MD = 0.84, 95% CI: 0.55–1.13, P < 0.001) and increased intraoperative blood loss compared to CCSs (MD = 16.30, 95% CI: 3.79–28.82, P = 0.01). The necessity for a longer incision for the FNS arises from the need to adequately expose the surgical site to fix the femoral lateral plate, which involves removal of proximal femoral soft tissue and consequently results in increased intraoperative bleeding. Although these factors could potentially contribute to delayed healing and an elevated risk of infection, our study did not reveal a significant increase in these complications. Furthermore, no substantial differences were observed between FNS and CCS groups with respect to operation time (WMD = −4.88, 95% CI: −12.25 to 2.48, P = 0.19), length of hospital stay (MD = 0.10, 95% CI: −0.20 to 0.40, P = 0.52), or the excellent-to-good rate at the final follow-up [risk ratio (RR) = 1.05, 95% CI: 0.92–1.19, P = 0.50]. This observation may indicate minimal differences in surgical techniques and patient recovery trajectories. Factors including surgeon experience, intraoperative management skills, and postoperative care are likely to exert a similar influence on both procedures, potentially diminishing the inherent advantages of fixation systems. Furthermore, the comparable rates of excellent and good outcomes at the final follow-up imply that, although the femoral neck system (FNS) demonstrates certain short-term benefits, patients treated with the cannulated compression screw (CCS) approach can attain favorable functional recovery over time through effective rehabilitation.

In conclusion, compared to cannulated compression screws (CCS), the femoral neck system (FNS) presents distinct advantages in managing femoral neck fractures among young and middle-aged adults. These advantages include reduced operation time, decreased intraoperative fluoroscopy exposure, accelerated fracture healing, and a lower incidence of postoperative complications, such as femoral head necrosis, incision infection, delayed union, non-union, femoral neck shortening, and thigh pain. These findings indicate that the FNS holds promise for broader clinical adoption and application. Nonetheless, in clinical practice, the benefits of the FNS should be thoroughly assessed in conjunction with patient-specific variables, such as patient age, to ensure optimal outcomes.