Comparison of the femoral neck system and dynamic hip screw for femoral neck fracture: A systematic review and meta-analysis

Abstract

Introduction:

Recently, the femoral neck system (FNS) has been introduced as a novel fixation device, especially for femoral neck fracture (FNF); however, whether it can replace the widely used dynamic hip screw (DHS) remains unclear. This study aimed to compare the perioperative characteristics and clinical outcomes of FNS and DHS in the treatment of FNF.

Methods:

This systematic review and meta-analysis followed the PRISMA-P guidelines. A comprehensive search of MEDLINE, Embase, and the Cochrane Library was conducted up to December 10, 2024. Comparative studies evaluating DHS and FNS for FNF were included. Data were extracted on perioperative surgical parameters, postoperative complications, and functional outcomes. Pooled effect sizes were calculated using a random-effects model.

Results:

Eight studies involving 726 patients were included. FNS was associated with significantly shorter operative time (mean difference: −19.68 minutes; 95% CI: −26.36 to − 13.00; P < .001) and lower intraoperative blood loss (mean difference: −16.89 mL; 95% CI: −20.88 to −12.90; P < .001). There was no significant difference between FNS and DHS in terms of femoral neck shortening, nonunion, or osteonecrosis of the femoral head. Functional outcomes measured by Harris hip score were significantly better in the FNS group (mean difference: −1.40; 95% CI: −2.57 to −0.23; P = .02).

Conclusion:

FNS demonstrated shorter operative time, reduced blood loss, and improved functional outcomes compared to DHS, with comparable complication rates. These findings suggest that FNS may serve as a viable alternative to DHS for the treatment of FNFs.

1. Introduction

Femoral neck fracture (FNF) is a significant injury that commonly requires surgical intervention. Globally, the incidence of hip fractures is expected to markedly rise, reaching 21.3 million cases by 2050.^[1] Although most hip fractures occur in the elderly, FNFs may occur in younger patients following high-energy trauma. In younger populations, internal fixation, rather than arthroplasty, is preferred to preserve the native femoral head and avoid long-term complications associated with prosthetic implants.^[2] Accordingly, achieving stable fixation is crucial in this group.

Cannulated compression screws (CCS) and the dynamic hip screw (DHS) are common internal fixation options.^[3] DHS has demonstrated favorable outcomes in displaced and unstable fractures due to its mechanical stability.^[4] More recently, the femoral neck system (FNS) has been introduced as a novel fixation device to simplify the surgical procedure and reduce soft tissue disruption, comprising a neck bolt, anti-rotation screw, and locking plate, to provide angular and rotational stability with minimal invasiveness.^[5]

Many studies have compared CCS and DHS for FNF treatment. CCS is generally considered more minimally invasive than DHS, but numerous clinical and biomechanical studies agree that DHS offers superior mechanical stability.^[6] With the introduction of FNS, which aims to combine the advantages of CCS and DHS, comparisons between FNS and CCS have been increasingly reported.^[7–10] Biomechanical studies indicate that FNS provides greater mechanical strength than CCS,^[11] and early studies have shown favorable outcomes for FNS in treating FNFs.^[12] However, although DHS and FNS are widely used in clinical practice, large-scale and systematic comparisons between these 2 systems remain limited.

Therefore, this study aimed to compare the perioperative characteristics and clinical outcomes of FNS and DHS for FNF treatment. By synthesizing available evidence, we sought to evaluate whether FNS is a viable alternative to DHS and can replace it as the preferred FNF fixation method.

2. Materials and methods

2.1. Literature search

This study was conducted following the guidelines of the Cochrane Review and the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols.^[13,14] We searched the MEDLINE, Embase, and Cochrane Library databases for comparative studies that investigated surgical outcomes following fixation construct after FNF surgery. A systematic search was conducted for articles published from inception to December 10, 2024, following an a priori search strategy. Search terms included synonyms and related terms for FNF, FNS, and DHS as follows: (“femur neck” or “femoral neck” or “intracapsular”) and (“fracture” or “fractures”) and (“dynamic” or “compression” or “sliding”) and (“femur neck system” OR “femoral neck system” or “FNS”). There were no restrictions regarding language, publication year, or publication type. Following the initial electronic search, relevant studies and their reference lists were manually reviewed.

2.2. Study selection

Two board-certified orthopedic surgeons, with fellowship training in orthopedic hip and pelvic trauma, independently screened study titles and abstracts. When an abstract lacked sufficient information, the full article was assessed.

Target studies directly compared DHS and FNS outcomes following FNF fixation. Biomechanical and cadaveric studies, technical notes, letters to the editor, expert opinions, review articles, meta-analyses, conference abstracts, and case reports were excluded. We also excluded duplicate studies involving the same patient population, and those that should have been consolidated into a single publication.

At each stage of the selection process, the κ-value was calculated to assess inter-reviewer agreement, with values interpreted as follows: κ = 1, “perfect”; 0.8 ≤ κ < 1.0, “almost perfect”; 0.6 ≤ κ < 0.8, “substantial”; 0.4 ≤ κ < 0.6, “moderate”; 0.2 ≤ κ < 0.4, “fair”; and κ < 0.2, “slight” agreement. Any disagreements during the selection process were resolved through consensus between the 2 reviewers or by consulting a third investigator (a board-certified orthopedic surgeon).

2.3. Ethical approval

This study was a systematic review and meta-analysis of previously published studies and did not involve any new human subjects or identifiable personal data. Therefore, ethical approval and informed consent were not required.

2.4. Data extraction

For qualitative data synthesis, we systematically extracted and reviewed key information from the included studies as follows: study design; fixation methods used; number of patients in each group; mean patient age; sex distribution; Pauwels classification type; Garden classification and fracture displacement status; follow-up duration; DHS type used; use of anti-rotation screws; operation time; intraoperative blood loss; length of hospital stay; nonunion rates; osteonecrosis of the femoral head (ONFH); neck shortening measurements; postoperative infection; and Harris hip score (HHS) at the final follow-up.

As this meta-analysis focused on variables reported in at least 3 studies, we included data on operation time, intraoperative blood loss, neck shortening, nonunion, ONFH, and HHS for the pooled analysis.

For the meta-analysis, when essential data were unavailable in the publication, we derived them through a full-text review. If data were still unavailable, we contacted the corresponding authors for clarification. Data extraction was performed independently by 2 reviewers, with discrepancies resolved through discussion.

2.5. Risk of bias assessment

The quality of the included studies was evaluated using the Methodological Index for Nonrandomised Studies (MINORS) tool,^[15] which is widely accepted for assessing both randomized controlled trials (RCTs) and nonrandomised studies. The highest possible MINORS score for comparative studies is 24. Two reviewers independently conducted the quality assessment; differences in the evaluations were resolved through discussion.

2.6. Data synthesis and statistical analysis

Primary outcomes included operation time, intraoperative blood loss, neck shortening, incidence of nonunion, ONFH, and HHS, comparing DHS and FNS for FNF treatment. Comparative analyses between the 2 groups were conducted to evaluate these outcomes.

Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated for outcome comparisons. Study heterogeneity was evaluated using the I² statistic, with thresholds of 25%, 50%, and 75% indicating low, moderate, and high heterogeneity, respectively. Forest plots were used to display individual study results, pooled effect sizes, and overall summary estimates. A P-value of <.05 was considered statistically significant. Data synthesis was performed using a random-effects model, as this approach reduces the likelihood of overestimating effect sizes and accounts for between-study heterogeneity.^[16] Given the clinical and methodological differences among the included studies (e.g., variations in patient age, fracture type, and surgical techniques), we considered heterogeneity to be likely. Therefore, a random-effects model was deemed more appropriate, in line with current methodological guidance (Chapter 9.5.4).^[17] Publication bias was not evaluated, as per the Cochrane guidelines, which advise against such analysis when fewer than 10 studies are included (Chapter 10.4.3).^[17] All statistical analyses were performed using Review Manager (RevMan) version 5.3 (Copenhagen, Denmark; Nordic Cochrane Centre, Cochrane Collaboration, 2014).

3. Results

3.1. Study identification

Figure 1 outlines the study identification and selection processes. The initial search retrieved 152 articles. After removing 66 duplicates and adding 4 additional studies found through manual searches, 86 records remained for screening. Among these, 72 were excluded after title and abstract screening. Another 6 were excluded following full-text assessment: 4 due to irrelevance to the research topic and 2 because they lacked sufficient data. Ultimately, 8 studies met the inclusion criteria and were included in the meta-analysis. The level of agreement between the reviewers during the title and abstract screening stages was substantial (κ = 0.701 and κ = 0.781, respectively), and perfect agreement was achieved at the full-text review stage (κ = 1.0).

Figure 1.

Preferred reporting items for systematic reviews and meta-analyses (PRISMA) flow diagram describing the process of the literature selection.

3.2. Study characteristics and qualitative synthesis

Of the 8 studies,^{[7–10,18–21]} 7 were retrospective cohort studies,^{[7–10,18–20]} and 1 was an RCT.^[21] Four studies compared FNS and DHS only,^[18–21] and another 4 compared FNS, DHS, and CCS.^[7–10] A total of 726 patients had FNF; DHS was used to treat 365 patients (DHS group), whereas FNS was used to treat 361 patients (FNS group). The mean patient age ranged from 40.1 to 84.7 years. The proportion of female patients ranged from 25.0% to 74.2%. Regarding fracture classification for Pauwels type, 5 studies reported that they included all types of Pauwels type and provided the number of cases for each type; however, they did not perform subgroup analysis based on Pauwels classification.^{[8–10,18,20]} Regarding the Garden classification, 6 studies included displaced fractures (garden 3 and 4)^{[8–10,18,20,21]} whereas 1 included nondisplaced fractures (garden 1 and 2).^[7] Follow-up periods ranged from 6 to 14 months. Detailed demographic data are presented in Table 1. Three studies reported that they used the blade type of DHS,^[9,18,20] and 5 stated that they inserted anti-rotation screws in the DHS group.^{[8–10,19,21]} The length of stay ranged from 2.7 to 13.7 days. Detailed perioperative profiles are presented in Table 2, and surgical outcomes are shown in Table 3.

Table 1.

Summary of patient demographic data from the included studies.

	Study design	Fixation methods	Number of patients		Mean age (years)		Female sex		Pauwels type		Garden classification		Follow-up period
			DHS	FNS	DHS	FNS	DHS	FNS	DHS	FNS	DHS	FNS
Vazquez et al. (2021)[7]	RCS	FNS, DHS, CCS	16	15	83.4 ± 7.3	86.1 ± 4.6	10 (63%)	13 (87%)	N/A		1,2	1,2	6 months
Ge et al. (2023)[18]	RCS	FNS, DHS	52	43	48.2 ± 8.0	50.4 ± 7.4	15 (29%)	13 (30%)	All III: 30	All III: 28	2,3,4 Displaced: 45	2,3,4 Displaced: 38	25 weeks
Hong et al. (2023)[21]	RCT	FNS, DHS	45	45	55.2 ± 10.0	54.4 ± 9.6	20 (44%)	19 (42%)	N/A		2,3,4 Displaced: 30	2,3,4 Displaced: 33	6 months
Niemann et al. (2023)[19]	RCS	FNS, DHS	23	23	66 (IQR 57–75)		22 (48%)		N/A		N/A		33 weeks
Schuetze et al. (2023)[20]	RCS	FNS, DHS	108	113	68.5 ± 15.1	66.6 ± 21.5	112 (51%)		All III: 39	All III: 40	All Displaced: 37	All Displaced: 41	13 months
Xu et al. (2023)[8]	RCS	FNS, DHS, CCS	52	54	63.1 ± 13.2	60.7 ± 15.2	38 (73%)	36 (67%)	All III: 10	All III: 16	All Displaced: 9	All Displaced: 16	13 months
Cai et al. (2024)[9]	RCS	FNS, DHS, CCS	40	40	38.7 ± 11.1	41.5 ± 9.3	9 (23%)	11 (28%)	All III: 14	All III: 15	All Displaced: 20	All Displaced: 15	14 months
Lim et al. (2024)[10]	RCS	FNS, DHS, CCS	29	28	46 (range 18–64)	71 (range 30–88)	10 (35%)	18 (64%)	All III: 21	All III: 7	All Displaced: 21	All Displaced: 7	9 months

All values are presented as mean ± SD unless otherwise specified

CCS = cannulated cancellous screw, DHS = dynamic hip screw, FNS = femoral neck system, IQR = interquartile range, N/A = not available, RCS = retrospective comparative study, RCT = randomised controlled trial

Table 2.

Perioperative profile.

	DHS type	Anti-rotation screw for DHS	Operation time (min)		Blood loss (mL)		Length of stay (days)
			DHS	FNS	DHS	FNS	DHS	FNS
Vazquez et al. (2021)[7]	N/A	N/A	70.7 ± 20.0	43.3 ± 10.1	N/A		12.4 ± 5.3	10.3 ± 6.0
Ge et al. (2023)[18]	Blade	N/A	52.9 ± 9.6	47.1 ± 9.2	65.3 ± 17.9	48.5 ± 10.7	4.9 ± 0.9	5.1 ± 1.0
Hong et al. (2023)[21]	N/A	Inserted	49.2 ± 5.5	43.8 ± 8.0	107.7 ± 36.0	82.7 ± 21.5	N/A
Niemann et al. (2023)[19]	N/A	Inserted	N/A		N/A		N/A
Schuetze et al. (2023)[20]	Blade	N/A	54.7 ± 17.4	36.3 ± 11.6	*2.1 ± 1.4 g/dL	1.4 ± 1.2	11.3 ± 6.8	8.9 ± 4.3
Xu et al. (2023)[8]	N/A	Inserted	72 (IQR 55–88.8)	45 (IQR 40–59)	50 (IQR 30–50)	30 (IQR 20–50)	3.5 (IQR 3 to 6)	2.0 (IQR 2 to 4)
Cai et al. (2024)[9]	Blade	Inserted	52.2 ± 4.8	39.7 ± 2.8	59.1 ± 5.9	45.3 ± 9.6	13.5 ± 0.9	13.8 ± 0.9
Lim et al. (2024)[10]	N/A	Inserted	115 (IQR 88–142)	60 (IQR 40–80)	N/A		N/A

All values are presented as mean ± SD unless otherwise specified

DHS = dynamic hip screw, FNS = femoral neck system, IQR = interquartile range, N/A = not available

^*Haemoglobin difference between pre- and postoperative values

Table 3.

Outcome of Surgery.

	Non-union		ONFH		Neck shortening (mm)		Infection		HHS
	DHS	FNS	DHS	FNS	DHS	FNS	DHS	FNS	DHS	FNS
Vazquez et al. (2021)[7]	N/A		N/A		4.9 ± 7.9	6.7 ± 4.0	N/A		N/A
Ge et al. (2023)[18]	3	2	3	1	5.2 ± 2.9	3.9 ± 2.4	N/A		89.9 ± 4.9	92.3 ± 4.5
Hong et al. (2023)[21]	4	2	2	1	N/A		N/A		N/A
Niemann et al. (2023)[19]	N/A		1	0	5.0 (IQR 1.7 to 10.9)	5.4 (IQR 0.4 to 12.6)	N/A		95.9 (IQR 72.2 to 99.9)	94.7 (IQR 90.6 to 99.9)
Schuetze et al. (2023)[20]	11	14	N/A		4.8 ± 2.1	5.3 ± 1.9	3	0	N/A
Xu et al. (2023)[8]	2	3	0	0	1.9 (IQR 0.2 to 3.5)	2.1 (IQR 0.2 to 4.1)	N/A		91.5 (IQR 86.0 to 99.0)	94 (IQR 88.0 to 99.0)
Cai et al. (2024)[9]	3	2	5	4	3.9 ± 1.2	4.1 ± 1.1	1	1	91.4 ± 3.8	91.8 ± 3.7
Lim et al. (2024)[10]	1	1	4	2	0.0 (IQR 0.0–3.0)	0.0 (IQR 0.0–0.0)	N/A		N/A

All values are presented as mean ± SD unless otherwise specified

DHS = dynamic hip screw, FNS = femoral neck system, HHS = Harris hip score, IQR = interquartile range, N/A = not available, ONFH = osteonecrosis of femoral head

3.3. Methodological quality assessment

The mean MINORS score for the included studies was 16.8/24 (range, 14–23). Among the 8 core methodological criteria, all studies, except 1 RCT^[21] received a score of 0 for prospective data collection, unbiased assessment of the study endpoint, and prospective calculation of the study size.^{[7–10,18–20]} These domains are inherently limited in retrospective study designs and have been consistently underreported. Concerning follow-up adequacy, 5 studies received a point deduction due to either minimal follow-up duration or insufficient description of the follow-up period.^{[7,10,18,19,21]} Regarding the use of contemporary control groups, most studies compared the recently introduced FNS technique with traditional methods, which limited the feasibility of concurrent comparison. Three studies did not clearly state the time frame of comparison and were considered potentially noncontemporary.^[7,18,19] In contrast, 4 studies explicitly mentioned the period during which FNS was introduced and applied, suggesting partial contemporaneity.^[8–10,20] One RCT conducted parallel group comparisons during the same period, thus fully meeting the criterion.^[21] No point deductions were observed in other comparative domains, including adequacy of the control groups, baseline equivalence of the groups, and statistical analysis methods.

3.4. Meta-analysis results

3.4.1. Operation time

Seven studies compared the operation time between the DHS (n = 342) and FNS groups (n = 338).^{[7–10,18,20,21]} The pooled analysis showed that the mean difference in operation time was significantly longer in the DHS group than in the FNS group, with a mean difference of 19.68 min (95% CI: 13.00–26.36; P < .001; I² = 94%; Fig. 2A).

Figure 2.

Results of an aggregate analysis comparing (A) operation time and (B) intraoperative blood loss. CI = confidence interval, DHS = dynamic hip screw, FNS = femoral neck system, SD = standard deviation.

3.5. Intraoperative blood loss

Four studies compared intraoperative blood loss between DHS (n = 189) and FNS (n = 182).^[8,9,18,21] The pooled analysis demonstrated that intraoperative blood loss was significantly higher in the DHS group than in the FNS group, with a mean difference of 16.89 mL (95% CI: 12.90–20.88; P < .001; I² = 40%; Fig. 2B).

3.6. Neck shortening

Neck shortening was compared in 7 studies^{[7–10,18–20]}; however, the study by Lim et al was excluded from the meta-analysis due to a non-estimable mean difference, likely resulting from the use of zero values for both the mean and standard deviation in the FNS group.^[10] Thus, 6 studies compared femoral neck shortening between the DHS (n = 277) and FNS (n = 273) groups. The pooled analysis demonstrated a mean difference in femoral neck shortening of − 0.16 mm (95% CI: −0.54 to 0.22), indicating that the DHS group showed slightly less shortening than the FNS group; however, this difference was not statistically significant (P = .41; I² = 38%; Fig. 3A).

Figure 3.

Results of an aggregate analysis comparing (A) neck shortening, (B) nonunion or implant failure, (C) ONFH, and (D) HHS. CI = confidence interval, DHS = dynamic hip screw, FNS =femoral neck system, ONFH = osteonecrosis of femoral head, HHS = Harris hip score, SD = standard deviation.

3.7. Nonunion or implant failure

Six studies compared nonunion or implant failure between the DHS (n = 306) and FNS (n = 301) groups.^{[8–10,18,20,21]} The pooled analysis demonstrated that the DHS group had an OR of 1.04 for nonunion or implant failure compared to the FNS group (95% CI: 0.57–1.93), indicating virtually no difference between the groups; the result was not significant (P = .89; I² = 0%; Fig. 3B).

3.8. ONFH

ONFH was compared in 6 studies^{[8–10,18,19,21]}; however, the study by Xu et al was excluded from the meta-analysis because no events occurred in either group, making the OR non-estimable.^[8] Thus, 5 studies compared ONFH between the DHS (n = 189) and FNS (n = 179) groups. The pooled analysis demonstrated an OR of 1.82 (95% CI: 0.75–4.40) for ONFH in the DHS group compared to the FNS group; however, this difference was not significant (P = .18; I² = 0%; Fig. 3C).

3.9. HHS

Four studies compared HHS between the DHS (n = 158) and FNS (n = 148) groups.^[8,9,18,19] The pooled analysis demonstrated that the HHS was significantly higher in the FNS group than in the DHS group, with a mean difference of − 1.40 (95% CI: −2.57 to − 0.23; P = .02; I² = 0%; Fig. 3D).

4. Discussion

In our pooled study, compared to DHS, FNS demonstrated significantly shorter operative time, reduced intraoperative blood loss, and better functional outcomes as measured by HHS, with comparable results for complications. These findings suggest that FNS may serve as a viable alternative to DHS for the treatment of FNFs.

First, we outlined the characteristics of the included patient population. Five studies explicitly reported that all Pauwels types were included, and among the 559 patients analyzed, 220 (39%) were identified as having Pauwels type III–vertically oriented FNF–fractures.^{[8–10,18,20]} Since the literature reports differences in surgical implant selection based on the Pauwels type, with more vertically oriented fractures often requiring fixation with a DHS,^[4] it seems reasonable to interpret the data according to Pauwels classification. In biomechanical studies, FNS demonstrated significantly higher strength than CCS,^[11] suggesting that FNS may serve as a suitable replacement for CCS in non-vertically oriented FNFs. In contrast, given the comparable biomechanical stability between FNS and DHS, further comparison of these implants is warranted in vertically oriented FNFs. Unfortunately, such subgroup analysis could not be performed, as detailed information, particularly outcomes according to fracture pattern, was not reported in the included studies. Therefore, further research incorporating fracture stratification is required.

FNS was associated with a statistically significant reduction in operative time compared to DHS, with a pooled mean difference of 19.68 minutes. This result was consistent across all 7 included studies and is likely attributable to the simplified surgical technique of FNS. After the insertion of a single guide pin, the remaining steps in FNS are largely measurement-based and straightforward.^[5] In contrast, DHS typically requires a longer and more technically demanding surgical procedure than FNS. It generally involves more extensive muscular dissection, larger incisions, and longer suturing time. Additionally, the procedure includes triple reaming and more complex handling during implantation, all of which contribute to an increased operative time. The bulkier plate of the DHS must also be carefully contoured to fit the bone, which can further prolong surgery compared with FNS. In 5 of the 8 DHS studies, an additional anti-rotation screw was used to enhance fixation, which contributed to a longer operative time.^[22] These technical demands not only increase the operative time but also contribute to greater intraoperative blood loss. Compared to DHS, FNS requires a smaller incision and utilizes simpler instrumentation,^[20] which likely contributes to both shorter surgical times and reduced blood loss. These findings highlight the procedural advantages of FNS over DHS in terms of surgical efficiency and invasiveness.

Five of the 6 studies reported slightly more femoral neck shortening in the FNS group,^{[7–10,19,20]} while 1 study reported the opposite.^[18] However, the measured differences were generally within 2 mm, making it difficult to determine their clinical significance. Multiple factors may contribute to neck shortening along with implant selection, including age, weight, fracture morphology, and fracture displacement.^[23] Given the comparable outcomes in biomechanical studies comparing the 2 systems,^[11] it is difficult to draw definitive conclusions on the impact of implant design alone on neck shortening.

In terms of complications, such as nonunion and ONFH, no significant differences were observed between the 2 groups. These complications are likely to be more influenced by the initial degree of displacement and accuracy of reduction rather than the type of implant itself.^[24,25] Despite differences in the inclusion criteria and fracture type distribution across studies, the DHS and FNS groups were generally similar in the Pauwels and Garden classifications within each study. Therefore, it seems reasonable to compare the complication rates between the 2 groups, and the absence of a significant difference may be interpreted as a valid finding.

Although FNS showed superior functional outcomes, it is worth noting that the DHS group also achieved excellent mean HHS values, with the lowest reported score being 89.9.^[26] Nevertheless, in relatively younger patients undergoing ORIF for FNF, even small improvements in functional outcomes may have long-term implications. FNS requires smaller incisions and less soft tissue dissection overall.^[5] It also avoids the need for an additional procedure associated with the insertion of a separate anti-rotation screw, where the placement of a new guide pin may lead to additional surgical trauma. In addition, the functional advantage of FNS may be partially attributed to its shorter operative time and reduced intraoperative blood loss, which may promote faster recovery.

This study had some limitations. First, only a small number of comparative studies were available for inclusion, which may have limited the generalisability of the findings. Second, only 1 of the 8 included studies was a randomized controlled trial (RCT); the others were retrospective, which may have introduced selection and information biases due to uneven distribution of confounding factors (e.g., fracture type, displacement, patient age, use of anti-rotation screws). This design limitation was also reflected in the MINORS scores, with most studies scoring poorly on prospective data collection and sample size calculation. The overall methodological quality was moderate (mean: 16.8/24), potentially limiting the reliability of our findings. Third, subgroup analysis based on Pauwels classification was not performed, although fracture verticality may influence the choice of fixation method. This limitation stemmed from the fact that most of the included studies did not provide outcome data stratified by fracture type, making such an analysis infeasible. Fourth, the included studies had relatively short follow-up durations, and as complications such as osteonecrosis of the femoral head may occur in the long-term, extended follow-up is necessary for a comprehensive outcome assessment. Fifth, the analysis of operation time showed substantial heterogeneity (I²=94%) which likely reflects variations in surgical technique, surgeon experience, and institutional practices. Although we used a random-effects model to account for this variability, the pooled estimate should still be interpreted with caution.

5. Conclusion

Compared to DHS, FNS demonstrated significantly shorter operative time, reduced intraoperative blood loss, and better functional outcomes as measured by HHS, with comparable results for complications. These findings suggest that FNS may serve as a viable alternative to DHS in the treatment of FNFs, though further high-quality RCTs with long-term follow-up are needed to validate these results.

Author contributions

Conceptualization: Eic Ju Lim.

Formal analysis: Jae Young Yang.

Supervision: Joo Yong Lee.

Visualization: Hyun-Chul Shon.

Writing – Original draft: Eic Ju Lim.

Writing – Review & editing: Chul-Ho Kim.