Biomechanical comparison of the femoral neck system and the dynamic hip screw in basicervical femoral neck fractures

Two-year outcomes of internal fixation with femoral neck system in patients with femoral neck fracture in an Asian population

Background

Femoral neck fractures (FNF) are one of the most common fractures, with a projected increase in incidence with population growth and ageing. The Femoral Neck System (FNS) launched in 2019 was developed specifically for fixation of FNF with the purported advantages of providing both angular and rotational stability. We report our experience with the FNS and evaluate its effectiveness and associated complications.

Methods

A retrospective case series of 50 patients who underwent surgical fixation for FNF from August 2020 to October 2021 using the FNS in two Singapore tertiary institutions with at least 2 years follow-up were included. Clinical data (patients' demographics, fracture classification, intra-operative and post-operative complications) were reviewed. Radiological analysis assessed the pre- and immediate post-operative garden alignment index (GAI) and presence of femoral neck shortening at 3 months.

Results

The mean age was 63.5 years (SD 16.9, range 26-92). Five (10 %), 34 (68 %) and 11 (22 %) were ASA 1, 2 and 3 respectively. Twenty-four (48 %), 16 (32 %), 4 (8 %), and 6 (12 %) patients sustained Garden's 1, 2, 3 and 4 FNF respectively. The mean operative duration was 66.2 min (SD 20.5) and length of stay was 6.9 days (SD 4.6).The post-operative improvement in garden alignment index (GAI) was a mean of 9.1° (p < 0.001) on lateral view. The mean femoral neck shortening was 1.97 mm (SD 5.3) at 3 months. There were no intra-operative complications. Post-operatively, 1 (2 %) patient required blood transfusion, 1 (2 %) patient had implant cut-out and non-union managed non-operatively, 2 (4 %) patients developed avascular necrosis and required revision to total hip replacements. There were two (4 %) cases of 1-year mortality.

Conclusion

The FNS achieved good outcomes with low rates of complications. The promising results justify its continued use and further evaluation in comparison to other devices.

Biomechanical analysis of various internal fracture fixation devices used for treating femoral neck fractures: A comparative finite element analysis

INTRODUCTION

Several internal fixation devices are available for treating Pauwels type I, II and III femoral neck fractures. The present study compared various fixation implants for all Pauwels fracture types using a CT-based subject-specific finite element model of the femur and determined the most effective implant for each fracture type.

MATERIALS AND METHODS

The analysis included four different configurations of cannulated screw models, Femoral Neck System, Dynamic Hip Screw and Dynamic Condylar Screw (with and without anti-rotational screw). Ti-alloy was considered as the implant material. Heterogeneous bone material property was assigned based on CT grey value. Frictional contact was assumed in the contact interfaces. Peak loading corresponding to normal walking and stair-climbing were considered. Equivalent strain in bone, equivalent stress in the implants, femoral head deformation and rotation, micromotion in the contact interfaces, and strain-shielding in bone were evaluated for each implanted model.

RESULTS

Stresses generated in the implants were within the yield limit of the implant material. In Pauwels I and II, the micromotion predicted at the contact regions in all the implanted models was within 100 µm, which is suitable for bone integration. However, in Pauwels III fracture, most of the implanted models other than DHS with AR-screw model exhibited micromotion of more than 150 µm in the contact regions, which is expected to inhibit bone growth.

CONCLUSIONS

The DHS with AR-screw implanted model was identified as the most effective in treating Pauwels I and III fractures. However, for Pauwels type II, DCS with an AR-screw implant was deemed superior to the other configurations.

Biomechanical comparison of femoral neck anti-rotation and support system versus femoral neck system for unstable pauwels III femoral neck fractures

BACKGROUND

The optimal treatment method for managing unstable Pauwels III femoral neck fractures remains undetermined. The aim of this study was to compare the biomechanical properties of two types of Femoral Neck Anti-rotation and Support System (FNAS) and a Femoral Neck System (FNS) in unstable Pauwels III femoral neck fractures.

METHODS

Eighteen synthetic femoral models were implanted with one of three fixation devices: FNS, FNAS I, or FNAS II. An unstable Pauwels III (OTA/AO 31-B2.3) femoral neck fracture was simulated using a custom-made needle and osteotomy guide. Torsion and axial compression loading tests were conducted, and the torque, torsion angle, load to failure, displacement, and stiffness values were recorded.

RESULTS

FNAS II exhibited significantly higher torsional stiffness (0.67 ± 0.10 Nm/°) compared to FNAS I (0.52 ± 0.07 Nm/°, P = 0.01) and FNS (0.54 ± 0.07 Nm/°, P = 0.005). FNS demonstrated significantly greater mean axial stiffness (239.24 ± 11.38 N/mm) than both FNAS I (179.33 ± 31.11 N/mm, P = 0.005) and FNAS II (190.07 ± 34.11 N/mm, P = 0.022). FNAS I (302.37 ± 33.88 N/mm, P = 0.001) and FNAS II (319.59 ± 50.10 N/mm, P < 0.001) showed significantly higher initial axial stiffness compared to FNS (197.08 ± 33.68 N/mm). Both FNAS I and II improved resistance to deforming forces at a load level before approximately 1000 N, which is sufficient to withstand the load from most daily life activities. No significant differences were observed in compression failure load among the groups. The failure patterns at the point of failure included the pull-out of the distal locking screw and reverse oblique intertrochanteric femur fracture for FNS, while for FNAS I and II, the failures were characterized by a cleft on the calcar femorale and a decrease in the load-displacement curve.

CONCLUSIONS

In unstable Pauwels III femoral neck fractures, the FNAS II enhances stability and is easier to manage for reoperation. The results of the current study support the potential of FNAS II as an alternative option for treating unstable Pauwels III femoral neck fractures in young individuals.

A recent update on the fixation techniques for femoral neck fractures: A narrative review

Femoral neck fractures present significant challenges in orthopedic surgery, particularly due to technical difficulties and a high complication rate. Surgical intervention is generally recommended, with osteosynthesis and arthroplasty being the main treatment options. Osteosynthesis techniques, including dynamic hip screw (DHS), multiple cannulated screws (MCS), and the femoral neck system (FNS), aim to achieve stable fixation and facilitate fracture healing. Factors influencing the choice of osteosynthesis include fracture displacement, bone quality, patient age, and the presence of posterior tilt. While DHS offers high stability, MCS is preferred in stable type fractures with minimal invasive procedures. FNS, a newer technique, combines the advantages of DHS and MCS, providing strong fixation with minimal soft tissue damage. Considering the comprehensive findings of biomechanical and clinical studies to date, when performing osteosynthesis for unstable femoral neck fractures, caution should be exercised with MCS as it may have slightly inadequate fixation strength compared to DHS and FNS. FNS, being the newest technique, demonstrates superior fixation strength comparable to DHS and is as minimally invasive as MCS. However, it is essential to remember that long-term follow-up results are lacking for FNS.

A finite element analysis of a low-profile femoral neck system of screws in sleeves in a vertical femoral neck fracture model

BACKGROUND

Femoral neck system (FNS) has exhibited some drawbacks, such as non-fit of the plate with the lateral femoral cortex, postoperative pain, and the potential risk of subtrochanteric fractures. We have developed a low-profile FNS system that addresses some compatibility issues in FNS. In this study, we conducted finite element analysis on the 1-hole FNS (1 H-FNS), 2-holes FNS (2 H-FNS), and low-profile FNS (LP-FNS) and compared their biomechanical performance.

METHODS

After the mesh convergence analysis, we established three groups of 1 H-FNS, 2 H-FNS, and LP-FNS. The interfragmentary gap, sliding distance, shear stress, and compressive stress and the bone-implant interface compression stress, stiffness, and displacement were determined under the neutral, flexion, or extension conditions of the hip joint, respectively. The stress and displacement of the femur after the implant removal were also investigated.

RESULTS

(1) There were no obvious differences among the three FNS groups in terms of the IFM distance. However, the LP-FNS group showed less rotational angle compared with conventional FNS (neutral: 1 H-FNS, -61.64%; 2 H-FNS, -45.40%). Also, the maximum bone-implant interface compression stress was obviously decreased under the neutral, flexion, or extension conditions of the hip joint (1 H-FNS: -6.47%, -20.59%, or -4.49%; 2 H-FNS: -3.11%, 16.70%, or -7.03%; respectively). (2) After the implant removal, there was no notable difference in the maximum displacement between the three groups, but the maximum von Mises stress displayed a notable difference between LP-FNS and 1 H-FNS groups (-15.27%) except for the difference between LP-FNS and 2 H-FNS groups (-4.57%).

CONCLUSIONS

The LP-FNS may not only provide the same biomechanical stabilities as the 1 H-FNS and 2 H-FNS, but also have more advantages in rotational resistance especially under the neutral condition of the hip joint, in the bone-implant interface compression stress, and after the implant removal. In addition, the 1 H-FNS and 2 H-FNS have similar biomechanical stabilities except for the maximum von Mises stress after the implant removal. The femur after the LP-FNS removal not only is subjected to relatively little stress but also minimizes stress concentration areas.

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

Background

Femoral neck fractures need to be treated in their early stages with accurate reduction and stable fixation to reduce complications. The authors compared the early radiologic outcomes of femoral neck fractures treated with the recently introduced Femoral Neck System (FNS, Depuy-Synthes) with conventional cannulated screws (CS) in a multicenter design. Furthermore, the factors associated with early failure after FNS were analyzed.

Methods

The FNS group included 40 patients treated between June 2019 and January 2020, and the CS group included 65 patients treated between January 2015 and May 2019. The operation was performed in 3 university hospitals. Patient demographics, fracture classification, postoperative reduction quality, sliding distance of FNS or CS, union and time to union, and complication rates were examined. Logistic regression analysis was performed on candidate factors for early failure of the FNS group.

Results

The FNS group had a 90% union rate and a mean time to union of 4.4 months, while the CS group had similar results with an 83.1% union rate and a mean time to union of 5.1 months. In the subgroup analysis of Pauwels type III fractures, the union rates were 75.0% and 58.8% in the FNS and CS groups, respectively, and the time to union was significantly shorter in the FNS group with 4.8 months compared to 6.8 months in the CS group. Early failure rate within 6 months of FNS fixation was observed to be 10%, which included 3 reduction failures and 1 excessive sliding with a broken implant. Risk factors for early failure after FNS were identified as displaced fractures (Garden classification type III or IV), poor reduction quality, longer tip-apex distance, greater sliding distance, and 1-hole implants, of which sliding distance was the only significant risk factor in multivariate analysis.

Conclusions

In femoral neck fractures, FNS and CS did not show significant differences for short-term radiologic results. FNS resulted in shorter operative time than cannulated screw fixation and favorable outcomes in Pauwels type III femoral neck fractures. The FNS could be considered a reliable and safe alternative to CS when treating femoral neck fractures.

Treatment of Delbet II/III Pediatric Femoral Neck Fractures With Proximal Femoral Locking Plate Versus Cannulated Screws

INTRODUCTION

Complications following operative treatment of pediatric femoral neck fractures include nonunion, coxa vara, and avascular necrosis (AVN). Proximal femoral locking plates (PFLPs) provide a fixed-angle construct that may reduce the rates of coxa vara, but their use in pediatric femoral neck fractures has not been studied. The purpose of this study was to evaluate rates of union, coxa vara, and AVN in traumatic pediatric femoral neck fractures treated with PFLP or cannulated screws (CS).

METHODS

We retrospectively reviewed all traumatic, nonpathologic Delbet II/III femoral neck fractures in patients below 18 years of age treated with PFLP or CS. All cases had ≥6 months of radiographic follow-up to evaluate for osseous union and AVN. Changes in proximal femoral alignment were determined by measuring injured and contralateral femoral neck-shaft angle and articulotrochanteric distance (ATD) between 6 and 12 months postoperatively.

RESULTS

Forty-two patients were identified with mean age at surgery of 10.7±2.9 years (range 3.3 to 16.3 years) and mean follow-up of 36±27 months. Sixteen patients (38%) underwent PFLP fixation, whereas 26 patients (62%) underwent CS fixation. When compared with the CS cohort, the PFLP cohort had a greater proportion of males (87.5% vs. 50%, P =0.02) and Delbet III fractures (68.8% vs. 15.4%, P <0.001). There was no difference between PFLP and CS cohorts with respect to rates of union (81% vs. 88%, respectively, P =0.66), AVN (25% vs. 35%, respectively, P =0.73), or secondary surgery (62% vs 62%, P =0.95). There was no significant difference in neck-shaft angle between injured and contralateral hips in those patients treated with PFLP ( P =0.93) or CS ( P =0.16). However, the ATD was significantly decreased in hips treated with CS compared with the contralateral hip (18.4±4.6 vs. 23.3±4.2 mm, P =0.001), with no significant difference in the PFLP group ( P =0.57).

CONCLUSIONS

This study suggests that the use of a PFLP in Delbet II/III femoral neck fractures does not appear to significantly increase nonunion rates or AVN and maintains anatomic ATD when compared with screw fixation.

LEVEL OF EVIDENCE

Level III-therapeutic study.

Bio-mechanical effects of femoral neck system versus cannulated screws on treating young patients with Pauwels type III femoral neck fractures: a finite element analysis

INTRODUCTION

As a novel internal fixation for femoral neck fractures, the femoral neck system has some advantages for young Pauwels type III femoral neck fractures without clear biomechanical effects and mechanisms. Thus, the objection of the study is to realize the biomechanical effects and mechanism of FNS cannulated screws on treating young patients with Pauwels type III femoral neck fractures compared to cannulated screws which are commonly used for femoral neck fractures by finite element analysis.

METHODS

Firstly, the model of young Pauwels type III femoral neck fractures, femoral neck system (FNS), and three cannulated screws (CS) arranged in an inverted triangle were established, and the internal fixations were set up to fix young Pauwels type III femoral neck fractures. Under 2100 N load, the finite element was performed, and the deformation, peak von Mises stress (VMS), and contact at fracture segments were recorded to analyze the biomechanical effects and mechanism of FNS and three-CS fixing young Pauwels type III femoral neck fractures.

RESULTS

Compared to three-CS, the deformation of the whole model, internal fixation, and fracture segments after FNS fixation were lower, and the peak VMS of the whole model and the internal fixation after FNS were higher with lower peak VMS of the distal femur and the fracture segments. With a sticking contact status, the contact pressure at fracture segments after FNS fixation was lower than that of three-CS.

CONCLUSIONS

FNS can provide better mechanical effects for young patients with Pauwels type III femoral neck fractures, which may be the mechanical mechanism of the clinical effects of FNS on femoral neck fracture. Although there is high stress on FNS, it is still an effective and safe internal fixation for young patients with Pauwels type III femoral neck fractures.

Fixation of femoral neck fracture with femoral neck system: a retrospective cohort study of 43 patients

BACKGROUNDS

This study aimed to analyze the clinical outcomes of femoral neck fractures (FNF) in patients treated with a femoral neck system (FNS, DePuy Synthes), which is a recently introduced device.

METHODS

This retrospective cohort study of 43 patients who underwent osteosynthesis using FNS for FNF between July 2019 and June 2021 with a minimum follow-up of 6 months. The researchers examined the patients' demographic factors and radiologically evaluated the fracture type and fixation status, bone union, and postoperative complications.

RESULTS

Of 43 patients, 25 were female, and the patients' mean age and body mass index were 62.1 years and 22.5 kg/m2, respectively. According to the Association of Osteosynthesis/Orthopaedic Trauma Association (AO/OTA) classification, the most common fracture types were 31B1.1 and B1.2 (13 cases each), followed by B2.3, B2.1, and B2.2 (seven, five, and four cases, respectively). Radiological bone union was confirmed in 39 patients (90.7%), and the mean time to union was 3.6 months. Two cases of nonunion, one case of lag screw cut-out, and one case of osteonecrosis were confirmed; all four cases later underwent arthroplasty. The mean time to reoperation was 4.5 months. Meanwhile, five patients underwent implant removal after the bone union, and distal locking screw stripping was noted in three patients. All three patients required metal plate cutting to remove the implants.

CONCLUSIONS

Osteosynthesis of FNF using the newly introduced FNS showed favorable clinical outcomes and no specific hardware-related complications were reported during the follow-up. However, attention must be paid to the issue regarding distal locking screw failure during hardware removal.

[Early effectiveness of Ti-Robot assisted femoral neck system for minimally invasive treatment of elderly Garden type Ⅱ and Ⅲ femoral neck fractures]

Objective

To investigate the early effectiveness of the Ti-Robot assisted femoral neck system (FNS) in the treatment of elderly Garden type Ⅱ and Ⅲ femoral neck fractures.

Methods

A retrospective analysis was conducted on the clinical data of 41 elderly patients with Garden type Ⅱ and Ⅲ femoral neck fractures who were admitted between December 2019 and August 2022 and met the selection criteria. Among them, 21 cases were treated with Ti-Robot assisted FNS internal fixation (study group), and 20 cases were treated solely with FNS internal fixation (control group). There was no significant difference in baseline data, including gender, age, side, cause of injury, time from injury to surgery, fracture Garden classification, and fracture line classification, between the two groups ( P>0.05). Surgical effectiveness was evaluated based on parameters such as operation time (including incision time and total operation time), reduction level, number of dominant pin insertions, intraoperative fluoroscopy frequency, incision length, whether to extend the incision, need for assisted reduction, postoperative hospital stay, fracture healing time, incidence of osteonecrosis of the femoral head, postoperative visual analogue scale (VAS) score at 1 day, and Harris hip score at last follow-up.

Results

The study group showed significantly shorter incision time, fewer dominant pin insertions, fewer instances of extended incisions, fewer intraoperative fluoroscopy frequency, and smaller incisions than the control group ( P<0.05). There was no significant difference in total operation time, reduction level, and assisted reduction frequency between the two groups ( P>0.05). Both groups achieved primary wound healing postoperatively, with no complications such as incision leakage or skin infection. All patients were followed up 12-24 months with an average of 14.6 months. Fractures healed in both groups, with no significant difference in healing time ( P>0.05). There was no significant difference in postoperative hospital stay between the two groups ( P>0.05). The study group showed significantly better VAS score at 1 day after operation and Harris hip score at last follow-up when compared to the control group ( P<0.05). No complication such as internal fixation failure, fracture displacement, or hip joint varus occurred in both groups during the follow-up. Osteonecrosis of the femoral head occurred in 1 patient of the control group, while no was observed in the study group, and the difference in the incidence of osteonecrosis of the femoral head between the two groups was not significant ( P=0.488).

Conclusion

Compared to sole FNS internal fixation treatment, Ti-Robot assisted FNS internal fixation for elderly Garden typeⅡ and Ⅲ femoral neck fractures can reduce incision time, achieve minimally invasive and accurate nail implantation, and decrease intraoperative fluoroscopy frequency, leading to improved postoperative hip joint function recovery.

A meta-analysis comparing the effects of cemented and uncemented prostheses on wound infection and pain in patients with femoral neck fractures

To providing evidence-based recommendations for surgery in patients with femoral neck fractures, a meta-analysis was conducted to comprehensively evaluate the effects of cemented and uncemented prostheses on postoperative surgical site wound infection and pain in these patients. Relevant studies on the use of cemented prostheses in femoral neck fractures were retrieved from PubMed, EMBASE, Cochrane Library, Ovid, CNKI, and Wanfang databases from the time of their establishment until March 2023. Two authors independently screened and extracted data from the included and excluded literature according to predetermined criteria. Review Manager 5.4 software was used to perform meta-analyses on the collected data. A total of 27 articles comprising 34 210 patients (24 646 cases in the cemented group and 9564 cases in the uncemented group) were included in the final analysis. The results of the meta-analysis showed that, compared with the uncemented group, cemented prostheses significantly reduced the incidence of surgical site wound infections (odds ratio [OR]: 0.75, 95% confidence interval [CI]: 0.64-0.88, p < 0.001) and relieved surgical site wound pain (standardised mean difference: -0.76, 95% CI: -1.12-0.40, p < 0.001), but did not reduce the incidence of pressure ulcers after surgery (OR: 0.50, 95% CI: 0.20-1.26, p = 0.140). Therefore, existing evidence suggests that the use of cemented prostheses in femoral neck fracture surgery can significantly reduce the incidence of surgical site wound infections and relieve surgical site wound pain, which is worthy of clinical recommendation.

Characteristics and Treatment Strategies for Basicervical and Transcervical Shear Fractures of the Femoral Neck

This study aimed to define basicervical and transcervical shear fractures using area classification and to determine the optimal osteosynthesis implants for them. The clinical outcomes of 1042 proximal femur fractures were investigated. A model of the proximal femur of a healthy adult was created from computed tomography images, and basicervical and transcervical shear fractures were established in the model. Osteosynthesis models were created using a short femoral nail with a single lag screw or two lag screws and a long femoral nail with a single lag screw or two lag screws. The minimum principal strains of the fracture surfaces were compared when the maximum loads during walking were applied to these models using finite element analysis software. Basicervical fractures accounted for 0.96% of all proximal femur fractures, 67% of which were treated with osteosynthesis; the failure rate was 0%. Transcervical shear fractures accounted for 9.6% of all proximal femur fractures, 24% of which were treated with osteosynthesis; the failure rate was 13%. Finite element analysis showed that transcervical shear fracture has high instability. To perform osteosynthesis, multiple screw insertions into the femoral head and careful postoperative management are required; joint replacement should be considered to achieve early mobility.

Superior short-term outcomes of FNS in combination with a cannulated screw in treating femoral neck fractures

BACKGROUND

This study aimed to evaluate the clinical efficacy of the femoral neck system alone or in combination with a cannulated screw compared with other internal fixation methods for treating femoral neck fractures. We further investigated the predictive effects of tip-apex distance (TAD) on clinical efficacy.

METHODS

Data from 129 young adults with femoral neck fractures followed up at The Second Affiliated Hospital of Fujian Medical University between January 2016 and June 2022 were retrospectively collected. The patients were categorized into four groups based on the different internal fixation methods. Analysis and comparisons of the four group were performed according to age, ASA score, operation time, blood loss, fracture classification, fracture healing time, Harris score, TAD value, presence of complications (osteonecrosis of the femoral head, screw failure, and femoral neck shortening), and changes in the neck-shaft angle.

RESULTS

All 129 patients were followed up for at least one year. The group who received treatment with the femoral neck system combined with a cannulated screw exhibited the shortest fracture healing time. Differences were observed in the change of neck-shaft angle among the four groups (P < 0.001), with the smallest change observed in the aforementioned group (0.76 ± 0.54°). The femoral neck shortening was also lower in groups with the femoral neck system or combined with a cannulated screw. At the last follow-up surgery, the combined treatment group achieved the highest HHS score. Subgroup analysis revealed that when the TAD was less than 25 and 49 mm for the femoral neck system and combined groups, respectively, there was less femoral neck shortening, less change in the neck-shaft angle, and a higher HHS score.

CONCLUSIONS

The femoral neck system alone or combined with a cannulated screw demonstrated better short-term efficacy in the treatment of femoral neck fractures. Furthermore, TAD may serve as a predictive indicator of the potential success of femoral neck fracture treatment.

Restoration of Hip Geometry after Femoral Neck Fracture: A Comparison of the Femoral Neck System (FNS) and the Dynamic Hip Screw (DHS)

BACKGROUND

The femoral neck system (FNS) was introduced as a minimally invasive fixation device for managing femoral neck fractures.

OBJECTIVE

To compare radiographic, clinical, and patient-reported outcome measures (PROMs) of femoral neck fracture patients following FNS compared to dynamic hip screw (DHS) implantation combined with an anti-rotational screw.

METHODS

Patients who underwent closed reduction and internal fixation of a femoral neck fracture between 2020 and 2022 were retrospectively included. We measured leg length, femoral offset, and centrum-collum-diaphyseal (CCD) angle in plain radiographs. Scar length, Harris Hip Score, short-form health survey 36-item score (SF-36), and Numeric Rating Scale (NRS) were assessed during follow-up visits.

RESULTS

We included 43 patients (22 females) with a median age of 66 (IQR 57, 75). In both groups, leg length differences between the injured and the contralateral side increased, and femoral offset and CCD angle differences were maintained over time. FNS patients had shorter scars and reported fewer emotional problems and more energy. There were no differences between groups regarding the remaining SF-36 sub-scores, Harris Hip Score, and NRS.

CONCLUSIONS

The FNS allows for a comparable leg length, femoral offset, and CCD angle reconstruction while achieving similarly high functional and global health scores to the DHS.

Femoral neck system vs. cannulated screws on treating femoral neck fracture: a meta-analysis and system review

Objective

This meta-analysis aimed to compare the relative safety and efficacy of cannulated compression screw (CCS) and femoral neck system (FNS) in treating patients with femoral neck fractures and to provide evidence-based medical evidence for FNS in treating femoral neck fractures.

Methods

PubMed, Embase, Cochrane, and China National Knowledge Infrastructure databases were searched to collect outcomes related to femoral neck fractures treated with FNS and CCS, including time to fracture healing, incidence of non-union, incidence of osteonecrosis of the femoral head, incidence of failure of internal fixation, rate of femoral neck shortening, Harris hip score, Barthel index, operative time, intraoperative blood loss, fluoroscopy frequency, and complications. A meta-analysis was performed using RevManv5.4 (The Cochrane Collaboration) and Stata v14.0 software.

Results

This analysis included 21 studies involving 1,347 patients. The results showed that FNS was superior to CCS in terms of fracture healing time [mean difference (MD) = -0.75, 95% CI = (-1.04, -0.46), P < 0.05], incidence of bone non-union [odds ratio (OR) = 0.53, 95% CI = (0.29, 0.98), P = 0.04], incidence of osteonecrosis of the femoral head [OR = 0.49, 95% CI = (0.28, 0.86), P = 0.01], incidence of internal fixation failure [OR = 0.30, 95% CI = (0.18, 0.52), P < 0.05], rate of femoral neck shortening [OR = 0.38, 95% CI = (0.27, 0.54), P > 0.05], Harris hip score [MD = 3.31, 95% CI = (1.99, 4.63), P < 0.001], Barthel index [MD =  4.31, 95% CI = (3.02, 5.61), P < 0.05], intraoperative bleeding [MD = 14.72, 95% CI = (8.52, 20.92), P < 0.05], fluoroscopy frequency [OR = 0.53, 95% CI = (0.29, 0.98), P = 0.04], and complications [OR = 0.31, 95% CI = (0.22, 0.45), P < 0.05]. The difference between FNS and CCS in operative time was not statistically significant [MD = -2.41, 95% CI = (-6.88, 2.05), P = 0.29].

Conclusion

FNS treatment of femoral neck fracture can shorten the fracture healing time; reduce the incidence and translucent rate of bone non-union, osteonecrosis of the femoral head, and internal fixation failure; reduce intraoperative blood loss and postoperative complications; and improve hip joint function and activity. We are confident in the findings that FNS, an effective and safe procedure for internal fixation of femoral neck fractures, is superior to CCS.

Comparison of femoral neck system and three cannulated cancellous screws in the treatment of vertical femoral neck fractures: clinical observation and finite element analysis

OBJECTIVE

The purpose of this study was to compare the biomechanical and clinical results of two surgical methods for the treatment of vertical femoral neck fractures: Femoral neck system (FNS) and traditional three cannulated cancellous screws (CCS).

METHODS

First, we developed three different vertical femoral neck fracture models for the finite element analysis, with angles of 55°, 65°, and 75°, respectively. Two experimental groups were set up: the FNS group and the CCS group. Each fracture group was tested under axial loads of 2100 N to measure the femur's displacement, Von Mises stress (VMS), and its internal fixation components. Secondly, we retrospectively included the cases of vertical femoral neck fractures with FNS and CCS in our hospital from May 2019 to May 2021. In this study, we compared the duration of intraoperative fluoroscopy, operative time, hospital stay, fracture healing time, Hemoglobin loss, Harris score of hip joint function, and postoperative complications among patients undergoing hip joint replacement.

RESULTS

In terms of finite element analysis, FNS has better anti-displacement stability than CCS at 55°and 65°, while FNS is greater than CCS in Von Mises stress. Clinically, we followed up on 87 patients for an average of 12 months. FNS was superior to traditional CCS in fracture healing time, operation time, fluoroscopy duration, fracture healing time, and Harris hip function score.

CONCLUSION

FNS is superior to traditional CCS in biomechanical and clinical aspects of treating vertical femoral neck fractures. There is potential for FNS to become a new treatment option for vertical femoral neck fractures.

Survivability of the Femoral Neck System for the treatment of femoral neck fractures in adults

INTRODUCTION

Hip fractures are common injuries in the elderly, with an incidence that continues to rise. The femoral neck system (FNS) recently emerged as a novel treatment option for femoral neck fractures, but long-term survivability of the implant remains uncertain. The purpose of this study is to evaluate survivability of the FNS and assess risk factors for implant failure.

METHODS

One hundred five adult patients who received the FNS (DePuy Synthes, Raynham, MA) for femoral neck fractures (AO/OTA 31B) were included. Surgeries were performed within a regional hospital system comprising 18 facilities. All patients had a minimum follow-up of 1 year. The primary outcome measures were cumulative incidence of implant failure and 1-year mortality, including risk factor analysis.

RESULTS

Twelve implants failed at a follow-up ranging from 17 days to 8 months, and 7 failed within 90 days. Cumulative incidence of implant failure was 2% at 30 days, 7% at 90 days, 12% at 6 months, and 13% at 1 year. Causes of implant failure included cut-out (n = 5), non-union (n = 4), peri-implant fracture (n = 2), and avascular necrosis (n = 1). Univariate Cox regression identified Pauwels type III fractures and an increasing AP Parker ratio as significant risk factors for failure. Pauwels type III fractures showed a 5.48 times higher risk compared to Pauwels types I & II. Every 10% increase in AP Parker ratio increased risk of failure by 2.39 times. The 1-year mortality rate was 21%, and univariate logistic regression identified age as the only risk factor (odds ratio = 3.71).

CONCLUSIONS

The incidence of implant failure and 1-year mortality rate in this study suggests that the FNS can provide reliable fixation compared to rates in the literature, but complications are not uncommon. Avoiding Pauwels type III fractures and optimizing implant placement appear crucial to preventing implant failure.

LEVEL OF EVIDENCE

Therapeutic Level IV.

Evaluation of a Locking Autocompression Screw Model in Pauwels Type-3 Femoral Neck Fracture: In Vitro Analysis

Femoral neck fractures in young adults are uncommon, resulting from high-energy trauma. Despite their infrequency in this population, there is higher rate of complications, especially in the more vertical fracture line, classified by Pauwels as a type-3 femoral neck fracture. The implant type is of paramount importance for maintaining anatomical reduction, since it must resist the deforming forces that act on the fracture. We comparatively evaluated two constructions of the novel locking autocompression implant (X-PIN and X-PIN+P) using the finite element method and previously established methods for treating Pauwels type-3 femoral neck fractures. Six fixation models were developed for the study: a dynamic hip screw (DHS), a DHS with an anti-rotation screw (DHS+P), the inverted triangle multiple cannulated screws construction (ASNIS), the multiple cannulated screws in an L-configuration (L), and the two models of the novel locking autocompression screw (X-PIN and X-PIN+P). Under the same conditions with a load of 2100 N, the following parameters were evaluated using SIMLAB® software: the main maximum (Max P), main minimum (Min P), localized maximum P1 (Max P1), localized maximum P2 (Max P2), total displacement, localized displacement, rotation displacement, and von Mises stress. Compared to the DHS+P and ASNIS models, the X-PIN+P model presented, respectively, increases of 51.6% and 64.7% for Max P, 85% and 247% for Min P, and 18.9% and 166.7% for von Mises stress. Max P1 did not differ between the models, but Max P2 was 55% and 50% lower for X-PIN+P than ASNIS and L, respectively. All displacement values were lower for X-PIN+P than the other models. In this FEM testing, the X-PIN+P was superior to the other models, which was due to improvement in all parameters of stress distribution, displacement, and von Mises stress compared to models using a lateral plate (DHS and DHS+P) or not (ASNIS and L).

Biomechanical Assessment of Cannulated Nails for the Treatment of Proximal Femur Fractures

This article focuses on a type of surgical implant used in orthopaedics and traumatology—cannulated femoral nails. Femoral nails are used in medical treatment for purposes of osteosynthesis, i.e., when treating various types of complicated fractures, in this case fractures of the femur. The article investigates cases in which a nail has been implanted in the proximal part of the femur for a short time (with the fracture still not healed), compared with cases in which the bone has already healed. According to AO classification, examined fractures are described as AO 31B3 AO 32A3. The main focus is on strength-deformation analysis using the finite element method (FEM), which makes it possible to determine the behaviour of the femur-implant system. FEM analysis was used to compare 1.4441 steel nails made by two manufacturers, Medin (Czech Republic) and Tantum (Germany). Boundary conditions including external loading, prescribed supports and elastic foundation are defined. There were solved FEM analyses for five cases of healed femur and five cases of broken femur both including implants with prescribed collo-diaphyseal angles. The results of the analysis were used to assess stress-deformation states from the perspective of appropriateness for clinical treatment, biomechanical reliability and safety. All examined femoral nails are compared, safe and suitable for patient treatment.