Results of internal fixation of Pauwels type-3 vertical femoral neck fractures

Biomechanical comparison of Gofried positive support reduction of Pauwels type III femoral neck fractures: A finite elements analysis

OBJECTIVE

This study aims to investigate the biomechanical characteristics of non-anatomical reduction and different screw positions on the stability of Pauwels type III femoral neck fractures.

METHODS

Three-dimensional finite element models of femoral neck fractures were constructed using CT images. Four types of internal fixation methods were simulated, including biplane double-supported screw fixation (BDSF), three inverted triangular parallel cannulated screws (3CS), new parallel cannulated screws with posterior screws moving down (New 3CS), and two parallel cannulated screws (2CS). von Mises stress and total displacement were compared between the fracture models after the femoral head was subjected to an axial load of 2100 N. Stress and displacement data for the implants and the femur were recorded for each fixation method and compared.

RESULTS

The results demonstrated that positive reduction of a Pauwels type III femoral neck fracture provided greater stability than neutral or negative reduction. Specifically, the BDSF group showed the lowest maximum von Mises stress in the femur (17.66 MPa) in positive reduction, compared to 3CS (21.08 MPa), New 3CS (22.14 MPa), and 2CS (36.57 MPa). The total displacement of positive reduction in the BDSF group was 0.3143 mm, which was lower than in the 3CS (0.3498 mm), New 3CS (0.3343 mm), and 2CS (0.4533 mm) groups. The stress distribution in the positive support reduction group was lower than that of the other groups, indicating better load distribution. Among the three-screw fixation methods, the New 3CS system exhibited the highest stress in the screws (with a peak of 28.62 MPa), while the 2CS group displayed the highest stresses overall, both in the femur and the screws.

CONCLUSION

For Pauwels type III femoral neck fractures, a positive support reduction with BDSF fixation exhibited superior biomechanical performance than negative reduction. Based on the finite element analysis conducted in this study, the positive support reduction with BDSF fixation can enhance fixation stability, suggesting that non-anatomical reduction is recommended.

Risk factors for nonunion in femoral neck fracture patients with internal fixation: A multicenter (TRON group) retrospective study

INTRODUCTION

Femoral neck fractures (FNFs) are common in elderly individuals. When minimally displaced, they are typically treated with internal fixation. Nonunion is a complication of internal fixation of FNF, that sometimes necessitates reoperation. Radiographic parameters, including the Pauwels angle and posterior tilt angle, are risk factors for nonunion. However, these parameters are assessed solely in a two-dimensional context. We developed a novel radiographic parameter named the "Kindex." This multicenter investigation aimed to identify risk factors for nonunion following FNF fixation and evaluate the validity of this index.

METHODS

This retrospective multicenter study collected data from 939 FNF patients who underwent internal fixation between 2016 and 2020 at 11 facilities (TRON group). The following exclusion criteria were applied: age <65, insufficient data, and Garden Stage III or IV fracture. Patient data, including age, sex, BMI, ASA classification, alcohol and smoking history, and comorbidities, were recorded. Radiographic measurements of the Pauwels angle and posterior tilt angle at the time of injury were used to calculate the Kindex. Correlations between the Pauwels angle, posterior tilt angle, Kindex, and nonunion were evaluated. A multivariate logistic regression analysis was performed to investigate independent risk factors for nonunion. A receiver operating characteristic (ROC) analysis was performed to determine the cutoff value of the Kindex, and the area under the curve (AUC) was calculated.

RESULTS

The study included 594 patients (males, n = 151; females, n = 443; average age, 80.9 years). Nonunion was observed in 13 cases (2.2 %). While the Pauwels angle and posterior tilt angle did not show significant correlations, the Kindex exhibited strong correlations with both parameters. In the multivariate analysis, the Kindex and renal impairment were independent risk factors for nonunion (Kindex: OR 1.06, p = 0.015; renal impairment: OR 1.48, p = 0.021). In the ROC analysis, a Kindex of 50 was identified as the optimal cutoff value (AUC 0.72).

CONCLUSION

The nonunion rate after internal fixation of FNF was 2.2 %. Renal impairment and the Kindex were identified as independent risk factors. The Kindex at the time of injury may serve as a novel radiographic parameter to consider when evaluating the need for internal fixation in FNF cases.

CT scan-based 3D fracture mapping in civilian gunshot intracapsular fractures of the femur neck

INTRODUCTION

Displaced intracapsular neck of femur (NOF) fractures secondary to civilian gunshots are rare injuries with universally poor outcomes following surgical fixation. No studies have been published on fracture mapping in NOF fractures secondary to civilian gunshots.

OBJECTIVES

We performed CT scan-based fracture mapping to identify the most common fracture patterns in these injuries.

METHODS

Design: Retrospective search of prospectively collected data.

SETTING

Single Level 1 Trauma hospital. Patient selection criteria: All patients presenting with gunshot fractures to the femur neck between 01 January 2009 and 31 December 2022 were identified. Once identified from Picture Archiving and Communication System (PACS), computed tomography (CT) scans in Digital Imaging and Communication in Medicine (DICOM) format were imported into Mimics 16 software and fracture fragments were segmented and three-dimensional (3D) reconstruction was generated. The reduced fractures were exported to 3-Matic software to merge the fragments and adjust the orientation in three planes. An uninjured femur model was used as a template for reduction. Fracture lines and heat maps were then generated. Our outcome measures were successful mapping of the identified fracture lines.

RESULTS

A total of 25 intracapsular femur neck fractures were identified and suitable for CT scan mapping. All patients were male with an average age of 22 (range 18-32). Once generated, fracture maps were used to show the location, distribution and frequency of the fracture lines. In all but two cases the fracture line propagation remained within the confines of the hip joint capsule. In three cases there was fracture extension into the superior aspect of the femur head, and in one case extension into the inferior aspect.

CONCLUSION

This is the first study to perform 3D fracture mapping for intracapsular femur neck fractures secondary to civilian gunshot injuries. The exercise has helped us better understand the commonest fracture patterns and assisted us with surgical planning and execution.

Contralateral Neck-shaft Angle Lower Than 130° Is Associated With Clinical Failure in Nongeriatric Individuals: Analysis of the National Femoral Neck Fracture Database of 1066 Patients

BACKGROUND

Treatment of femoral neck fractures in patients who are nongeriatric (≤ 60 years) is challenging because of high failure rates. Anatomic parameters influence the biomechanical environment for fracture healing, but their associations with clinical prognosis remains unclear.

QUESTIONS/PURPOSES

(1) Which anatomic parameter that is identifiable on pelvic radiographs shows a statistical correlation with a higher risk of clinical failure defined as nonunion, avascular necrosis (AVN), reoperation, and functional failure (decrease in Harris hip score reaching the minimum clinically important difference) in the screw fixation of femoral neck fractures among nongeriatric patients? (2) How does the influence of anatomic parameters on clinical prognosis manifest: directly or mediated by additional mechanisms?

METHODS

This retrospective, multicenter study used a nationwide database in China. Between January 2014 and December 2020, we evaluated 1066 patients with femoral neck fractures with a median age of 53 years (interquartile range 46 to 56) and median follow-up period of 62 months. Anatomic parameters including femoral neck-shaft angle (NSA), femoral head radius, femoral neck width, femoral offset, acetabular center-edge angle, and acetabular sharp angle were variables of interest. The primary outcome was clinical failure including nonunion, AVN, reoperation, and functional failure (decrease in Harris hip score reaching the minimum clinically important difference). Risk factors for failure were first filtered using the Bayesian information criterion and then assessed with multiple regression adjusting for confounders. The mediation effect was further explored using model-based causal mediation analysis with a quasi-Bayesian Monte Carlo method.

RESULTS

Of all anatomic parameters we assessed, the contralateral NSA was associated with clinical failure, after adjusting for all potential covariates and confounding variables (adjusted odds ratio 0.92 [95% confidence interval 0.89 to 0.95]; p < 0.001). The optimal threshold for the NSA was 130°, with the highest Youden index of 0.27. Patients with an NSA < 130° (41% [441 of 1066]) demonstrated an increased occurrence of nonunion (15% [68 of 441] versus 5% [33 of 625]; p < 0.001), AVN (32% [141 of 441] versus 22% [136 of 625]; p < 0.001), functional failure (25% [110 of 441] versus 15% [93 of 625]), and reoperations (28% [122 of 441] versus 13% [79 of 625]). The impact of an NSA less than 130° on clinical failure was direct and substantially mediated by the type of displaced fracture (mediation proportion: 18.7%).

CONCLUSION

In our study of screw fixations for femoral neck fractures among nongeriatric patients, we identified that a contralateral NSA < 130° correlates with an increased risk of clinical failure including nonunion, AVN, functional failure, and reoperation. The effect is either direct or mediated through displaced fracture types. This is important for surgeons in order to recognize the elevated rate of clinical failure and nature of the challenging biomechanical environment, which should guide them in refining surgical details and selecting appropriate fixation and rehabilitation plans. Approaches to managing these fractures require further validation with large-scale clinical trials.

LEVEL OF EVIDENCE

Level III, prognostic study.

Global trends of Pauwels type III femoral neck fractures: bibliometric analysis and visualized study

Background

Pauwels type III femoral neck fractures, as a serious type of femoral neck fractures, have brought about a heavy economic burden on families and society for the high disability rate. Through bibliometric research and visualized analysis, this study aimed at elucidating the global research status of Pauwels type III femoral neck fractures to date, and predicting the future research trends in this field.

Methods

Publications and associated information on Pauwels type III femoral neck fractures to date were retrieved from Web of Science Core Collection, and by VoSviewer and R package "bibliometrix", bibliometric analysis and visual presentation was conducted.

Results

By retrieval, a total of 98 studies were refinedly extracted, and the volume of publications in this field increased year-over-year. China ranked first in terms of total publication volume and H-Index, with its total citation records second only to the United States. The country with the highest average citation frequency was Switzerland. SHANGHAI JIAO TONG UNIVERSITY was the most productive research institution. Among the authors in this field, Li, Jiantao had published the most researches. INJURY INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED and JOURNAL OF ORTHOPAEDIC TRAUMA were the two magazines with the highest publication volume, total citation records, and H-index. According to keywords co-occurrence analysis, the research content in the past 24 years is mainly divided into four different dimensions. Finite element analysis, femoral neck system, medial buttress plate, cannulated screws, hip screw, open reduction, complications are hot topics for future research.

Conclusions

According to the global trends analysis of publications production, Pauwels type III femoral neck fractures are receiving increasing attention and input from scholars. China has made the greatest scientific research contribution among countries, but its academic quality should be improved further. The modified therapeutic methods designed for addressing the complications of traditional internal fixation for Pauwels III femoral neck fractures will be the future research hotspot.

Comparative analysis of the femoral neck system (FNS) vs. cannulated cancellous screws (CCS) in the treatment of Middle-aged and elderly patients with femoral neck fractures: clinical outcomes and biomechanical insights

PURPOSE

This study aimed to compare the clinical outcomes and differences in biomechanical characteristics between the femoral neck system (FNS) and cannulated cancellous screws (CCSs) in the treatment of femoral neck fractures.

METHODS

This study retrospectively analysed a cohort of 38 registered cases of femoral neck fractures treated surgically with either the FNS (n = 17) or CCSs (n = 21) between January 2020 and December 2023. Indicators such as fluoroscopy frequency, length of hospital stay, and fracture healing time were compared between the two groups. Functional status was evaluated via the Harris hip score (HHS) and visual analogue scale (VAS), whereas prognosis was assessed based on changes in the neck shaft angle and femoral neck shortening. Additionally, six sets of femoral neck fracture models were developed based on Pauwels angles of 30°, 40°, 50°, 60°, 70°, and 80°. Two experimental groups, FNS and CCS, were established, and a joint reaction force of 1800 N was applied to the proximal femur. The displacement, stress, and stiffness of the components of interest in the different models were tested and compared.

RESULTS

The distributions of all the baseline characteristics were similar between the two groups (p > 0.05). The FNS group presented significantly shorter fluoroscopy frequency, length of hospital stay, and fracture healing time (p < 0.05). Harris and VAS scores were higher in the FNS group than in the CCS group (p < 0.05). Postoperative changes in the neck shaft angle and femoral neck shortening were significantly lower in the FNS group than in the CCS group (p < 0.05). The results of the finite element analysis indicated that the maximum stress on the femoral head and varus angle were generally lower in the FNS group than in the CCS group and that the maximum displacement of the femoral head and FNS was generally lower in the FNS group than in the CCS group. However, the superiority of FNS over CCS decreased with increasing Pauwels angle. Additionally, the effectiveness of FNS in limiting displacement of the femoral neck upper wall was not as favourable as that of CCS.

CONCLUSIONS

The treatment of femoral neck fractures with FNS is superior and contributes to improved hip joint function. Biomechanical research has confirmed its structural stability and advantages in resisting femoral head varus. However, challenges to its fixation efficacy persist, particularly at higher Pauwels angles.

Nonanatomical reduction of femoral neck fractures in young patients with different Pauwels classifications: a retrospective study and finite element analysis

BACKGROUND

Previous studies have reported that positive buttress is as effective as anatomical reduction in treating young femoral neck fractures, but whether this effect is related to the Pauwels classification remains unclear. The purpose of this study was to retrospectively analyze the clinical prognosis of positive buttress in young femoral neck fractures with different Pauwels classifications, as well as to assess its biomechanical properties.

METHODS

A total of 170 young patients with femoral neck fractures who were treated with three cannulated screws were included in this study. Patients were divided into three groups based on their preoperative Pauwels classification. Each group was divided into three subgroups based on the reduction quality: positive buttress, negative buttress and anatomical reduction. The femoral neck shortening, the incidence of necrosis of the femoral head (AVN) and the Harris hip scores at the last follow-up were compared across the three reduction quality within each Pauwels classification. Subsequently, a volunteer was recruited, CT data of the hip was obtained, and finite element models representing different reduction quality under varying Pauwels classifications were established. The biomechanical properties of each model were then evaluated following the application of strains.

RESULTS

In Pauwels type I, there were no significant differences in postoperative femoral neck shortening, incidence of AVN, or Harris score among the three types of reduction quality (P > 0.05). However, positive buttress provided superior biomechanical stability compared to negative buttress and anatomical reduction. In Pauwels type II, the incidence of AVN was similar between the positive buttress and the anatomical reduction groups, and both were significantly lower than that in the negative buttress (P < 0.05). The Harris score of the positive buttress was higher than that of the negative buttress, and there was no significant difference in the occurrence of femoral neck shortening between the three groups (P > 0.05). Finite element analysis showed that the biomechanical stability of positive buttress was equivalent to anatomical reduction, and both were better than negative buttress. In Pauwels type III, the incidence of AVN in the anatomical reduction group was lower than that in both the positive buttress and negative buttress (P < 0.05). There was no significant difference in the occurrence of AVN or femoral neck shortening between positive buttress and negative buttress (P > 0.05). There was also no difference in postoperative Harris scores between the three reduction qualities (P > 0.05). Both positive buttress and negative buttress exhibited identical biomechanical qualities and were inferior to anatomical reduction.

CONCLUSIONS

The biomechanical and clinical dominance of positive buttress correlates with Pauwels type. Specifically, Positive buttress is biomechanically stable in Pauwels types I and II. In Pauwels type III, positive buttress is not advantageous. As the Pauwels angle increases, the biomechanical benefit of the positive buttress is lost. Therefore, regardless of the Pauwels classification, negative buttress should be avoided after reduction of femoral neck fractures in young patients.

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.

Femoral Neck Fractures With Associated Ipsilateral Femoral Shaft Fractures in Young Adults <50 Years Old: A Multicenter Comparison of 80 Cases Versus Isolated Femoral Neck Fractures

OBJECTIVES

To analyze patients, injury patterns, and treatment of femoral neck fractures (FNFs) in young patients with FNFs associated with shaft fractures (assocFNFs) to improve clinical outcomes. The secondary goal was to compare this injury pattern to that of young patients with isolated FNFs (isolFNFs).

METHODS

DESIGN

Retrospective multicenter cohort series.

SETTING

Twenty-six North American level-1 trauma centers.

PATIENT SELECTION CRITERIA

Skeletally mature patients, <50 years old, treated with operative fixation of an FNF with or without an associated femoral shaft fracture.

OUTCOME MEASURES AND COMPARISONS

The main outcome measurement was treatment failure defined as nonunion, malunion, avascular necrosis, or subsequent major revision surgery. Odds ratios for these modes of treatment were also calculated.

RESULTS

Eighty assocFNFs and 412 isolFNFs evaluated in this study were different in terms of patients, injury patterns, and treatment strategy. Patients with assocFNFs were younger (33.3 ± 8.6 vs. 37.5 ± 8.7 years old, P < 0.001), greater in mean body mass index [BMI] (29.7 vs. 26.6, P < 0.001), and more frequently displaced (95% vs. 73%, P < 0.001), "vertically oriented" Pauwels type 3, P < 0.001 (84% vs. 43%) than for isolFNFs, with all P values < 0.001. AssocFNFs were more commonly repaired with an open reduction (74% vs. 46%, P < 0.001) and fixed-angle implants (59% vs. 39%) (P < 0.001). Importantly, treatment failures were less common for assocFNFs compared with isolFNFs (20% vs. 49%, P < 0.001) with lower rates of failed fixation/nonunion and malunion (P < 0.001 and P = 0.002, respectively). Odds of treatment failure [odds ratio (OR) = 0.270, 95% confidence interval (CI), 0.15-0.48, P < 0.001], nonunion (OR = 0.240, 95% CI, 0.10-0.57, P < 0.001), and malunion (OR = 0.920, 95% CI, 0.01-0.68, P = 0.002) were also lower for assocFNFs. Excellent or good reduction was achieved in 84.2% of assocFNFs reductions and 77.1% in isolFNFs (P = 0.052). AssocFNFs treated with fixed-angle devices performed very well, with only 13.0% failing treatment compared with 51.9% in isolFNFs treated with fixed-angle constructs (P = <0.001) and 33.3% in assocFNFs treated with multiple cannulated screws (P = 0.034). This study also identified the so-called "shelf sign," a transverse ≥6-mm medial-caudal segment of the neck fracture (forming an acute angle with the vertical fracture line) in 54% of assocFNFs and only 9% of isolFNFs (P < 0.001). AssocFNFs with a shelf sign failed in only 5 of 41 (12%) cases.

CONCLUSIONS

AssocFNFs in young patients are characterized by different patient factors, injury patterns, and treatments, than for isolFNFs, and have a relatively better prognosis despite the need for confounding treatment for the associated femoral shaft injury. Treatment failures among assocFNFs repaired with a fixed-angle device occurred at a lower rate compared with isolFNFs treated with any construct type and assocFNFs treated with multiple cannulated screws. The radiographic "shelf sign" was found as a positive prognostic sign in more than half of assocFNFs and predicted a high rate of successful treatment.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Treatment Failure After Repair of Displaced Femoral Neck Fractures in Patients Compared by "Decade of Life": An Analysis of 565 Cases in Adults Less Than 60 years of Age

OBJECTIVES

To study the results of displaced femoral neck fractures (FNFs) in adults less than 60 years of age by comparing patients, injury, treatment, and the characteristics of treatment failure specifically according to patients' age at injury, that is, by their "decade of life" [ie, "under 30" (29 years and younger), "the 30s" (30-39 years), "the 40s" (40-49 years), and "the 50s" (50-59 years)].

METHODS

DESIGN

Multicenter retrospective comparative cohort series.

SETTING

Twenty-six North American Level 1 Trauma Centers.

PATIENT SELECTION CRITERIA

Skeletally mature patients aged 18-59 years with operative repair of displaced FNFs.

OUTCOME MEASURES AND COMPARISONS

Main outcome measures were treatment failures (fixation failure and/or nonunion, osteonecrosis, malunion, and the need for subsequent major reconstructive surgery (arthroplasty or proximal femoral osteotomy). These were compared across decades of adult life through middle age (<30 years, 30-39 years, 40-49 years, and 50-59 years).

RESULTS

Overall, treatment failure was observed in 264 of 565 (47%) of all hips. The mean age was 42.2 years, 35.8% of patients were women, and the mean Pauwels angle was 53.8 degrees. Complications and the need for major secondary surgeries increased with each increasing decade of life assessed: 36% of failure occurred in patients <30 years of age, 40% in their 30s, 48% in their 40s, and 57% in their 50s (P < 0.001). Rates of osteonecrosis increased with decades of life (under 30s and 30s vs. 40s vs. 50s developed osteonecrosis in 10%, 10%, 20%, and 27% of hips, P < 0.001), while fixation failure and/or nonunion only increased by decade of life to a level of trend (P = 0.06). Reparative methods varied widely between decade-long age groups, including reduction type (open vs. closed, P < 0.001), reduction quality (P = 0.030), and construct type (cannulated screws vs. fixed angle devices, P = 0.024), while some variables evaluated did not change with age group.

CONCLUSIONS

Displaced FNFs in young and middle-aged adults are a challenging clinical problem with a high rate of treatment failure. Major complications and the need for complex reconstructive surgery increased greatly by decade of life with the patients in their sixth decade experiencing osteonecrosis at the highest rate seen among patients in the decades studied. Interestingly, treatments provided to patients in their 50s were notably different than those provided to younger patient groups.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Optimal Fixation Strategies for Displaced Femoral Neck Fractures in Patients 18-59 Years of Age: An Analysis of 565 Cases Treated at 26 Level 1 Trauma Centers

OBJECTIVES

The objective of this study was to determine the difference in failure rates of surgical repair for displaced femoral neck fractures in patients younger than 60 years of age according to fixation strategy.

METHODS

DESIGN

This is a retrospective, comparative cohort study.

SETTING

Twenty-six Level 1 North American trauma centers.

PATIENT SELECTION CRITERIA

Patients younger than 60 years of age with a displaced femoral neck fracture (OTA 31-B2, B3) undergoing surgical repair from 2005 to 2017.

OUTCOME MEASURES AND COMPARISONS

Patient demographics, injury characteristics, repair methods used, and treatment failure (nonunion/failed fixation, avascular necrosis, and need for secondary surgery) were compared according to fixation strategy.

RESULTS

Five hundred and sixty-five patients met inclusion criteria and were studied. The mean age was 42 years, 36% were female, and the average Pauwels' angle of fractures was 55 degrees. There were 305 patients treated with multiple cannulated screws (MCS) and 260 treated with a fixed-angle (FA) construct. Treatment failures were 46% overall, but was more likely to occur in MCS constructs versus FA devices (55% vs. 36%, P < 0.001). When FA constructs were substratified, the use of a sliding hip screw with addition of a medial femoral neck buttress plate (FNBP) and "antirotation" (AR) screw demonstrated better results than either FNBP or AR screw alone or neither with the lowest overall construct failure rate of 11% (P < 0.036).

CONCLUSIONS

Historically used fixation constructs for femoral neck fractures (eg, multiple cannulated screws and sliding hip screw) in young and middle-aged adults performed poorly compared with more recently proposed constructs, including those using a medial femoral neck buttress plate and an antirotation screw. Fixed-angle constructs outperformed multiple cannulated screws overall, and augmentation of fixed-angle constructs with a medial femoral neck buttress plate and antirotation screw improved the likelihood of successful treatment. Surgeons should prioritize fixation decisions when repairing displaced femoral neck fractures in patients.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Evaluating three internal fixation techniques for Pauwels III femoral neck fractures via finite element analysis

The selection of implants for fixing unstable femoral neck fractures (FNF) remains contentious. This study employs finite element analysis to examine the biomechanics of treating Pauwels type III femoral neck fractures using cannulated compression screws (3CS), biplane double-supported screw fixation (BDSF), and the femoral neck system (FNS). A three-dimensional model of the proximal femur was developed using computed tomography scans. Fracture models of the femoral neck were created with 3CS, BDSF, and FNS fixations. Von Mises stress on the proximal femur, fracture ends, internal fixators, and model displacements were assessed and compared across the three fixation methods (3CS, BDSF, and FNS) during the heel strike of normal walking. The maximum Von Mises stress in the proximal fragment was significantly higher with 3CS fixation compared to BDSF and FNS fixations (120.45 MPa vs. 82.44 MPa and 84.54 MPa, respectively). Regarding Von Mises stress distribution at the fracture ends, the highest stress in the 3CS group was 57.32 MPa, while BDSF and FNS groups showed 51.39 MPa and 49.23 MPa, respectively. Concerning implant stress, the FNS model exhibited greater Von Mises stress compared to the 3CS and BDSF models (236.67 MPa vs. 134.86 MPa and 140.69 MPa, respectively). Moreover, BDSF displayed slightly lower total displacement than 3CS fixation (7.19 mm vs. 7.66 mm), but slightly higher displacement than FNS (7.19 mm vs. 7.03 mm). This study concludes that BDSF outperforms 3CS fixation in terms of biomechanical efficacy and demonstrates similar performance to the FNS approach. As a result, BDSF stands as a dependable alternative for treating Pauwels type III femoral neck fractures.

Finite Element Analysis of Six Internal Fixations in the Treatment of Pauwels Type III Femoral Neck Fracture

OBJECTIVE

The current investigation sought to utilize finite element analysis to replicate the biomechanical effects of different fixation methods, with the objective of establishing a theoretical framework for the optimal choice of modalities in managing Pauwels type III femoral neck fractures.

METHODS

The Pauwels type III fracture configuration, characterized by angles of 70°, was simulated in conjunction with six distinct internal fixation methods, including cannulated compression screw (CCS), dynamic hip screw (DHS), DHS with de-rotational screw (DS), CCS with medial buttress plate (MBP), proximal femoral nail anti-rotation (PFNA), and femoral neck system (FNS). These models were developed and refined using Geomagic and SolidWorks software. Subsequently, finite element analysis was conducted utilizing Ansys software, incorporating axial loading, torsional loading, yield loading and cyclic loading.

RESULTS

Under axial loading conditions, the peak stress values for internal fixation and the femur were found to be highest for CCS (454.4; 215.4 MPa) and CCS + MBP (797.2; 284.2 MPa), respectively. The corresponding maximum and minimum displacements for internal fixation were recorded as 6.65 mm for CCS and 6.44 mm for CCS + MBP. When subjected to torsional loading, the peak stress values for internal fixation were highest for CCS + MBP (153.6 MPa) and DHS + DS (72.8 MPa), while for the femur, the maximum and minimum peak stress values were observed for CCS + MBP (119.3 MPa) and FNS (17.6 MPa), respectively. Furthermore, the maximum and minimum displacements for internal fixation were measured as 0.249 mm for CCS + MBP and 0.205 mm for PFNA. Additionally, all six internal fixation models showed excellent performance in terms of yield load and fatigue life.

CONCLUSION

CCS + MBP had the best initial mechanical stability in treatment for Pauwels type III fracture. However, the MBP was found to be more susceptible to shear stress, potentially increasing the risk of plate breakage. Furthermore, the DHS + DS exhibited superior biomechanical stability compared to CCS, DHS, and PFNA, thereby offering a more conducive environment for fracture healing. Additionally, it appeared that FNS represented a promising treatment strategy, warranting further validation in future studies.

Should a low starting point be abandoned for cannulated screw fixation of femoral neck fractures?

A validated femoral neck fracture model stabilized with three inverted cannulated screws was used to consider different intraoperative scenarios when the inferior screw hole is inadvertently started too inferiorly. These scenarios were to: (1) abandon the misplaced inferior screw hole and restart this hole more proximally, or (2) accept the mispositioned placement of the inferior screw and insert the remaining superior screws parallel or convergent to the inferior screw. Utilizing the second option and accepting the errant hole was associated with the greatest interfragmentary motion and stresses in the bone and hardware. In contrast, the first option created an improved mechanical environment for healing.

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.

Given the encouraging results of biomechanical studies on femoral neck fractures, are locking plates more safe?

This current study compares the clinical and radiological outcomes of femoral neck fractures in young adults treated with either cannulated screws (CS) or proximal femoral locking plates (PFLP). We conducted a retrospective study in patients aged 18 to 60 years with femoral neck fractures and investigated medical records between January 2005 and December 2016. Patients were divided into two groups based on implants, screw and plate, used for fixation assigned. In addition, two groups were compared for their complications and functional outcomes, which were assessed with Harris Hip Score (HHS) and Parker Palmer mobility scores. Sixty-nine of 104 patients met the inclusion criteria. Forty patients were treated with cannulated screws, while 29 were treated with a proximal femoral locking plate. The two groups were comparable in terms of their perioperative variables. The overall complication rate (screw group, n = 10; plate group, n = 14) and non-union rate were significantly high in the plate group (p < 0.05). Other complications did not show statistically significant differences. The screw group had better functional outcomes than the plate group, where only the Parker-Palmer mobility score comparison was significant (p < 0.05). Poor reduction quality and Pauwels' type III fractures were statistically associated with high complication rates regardless of the implants used (p < 0.05). Although PFLP showed better outcomes in biomechanical studies than CSs, we observed poorer clinical results. Therefore, although some of our results appeared to be statistically significant, reduction quality should also be considered.

Biomechanical study of a biplanar double support screw (BDSF) technique based on Pauwels angle in femoral neck fractures: finite element analysis

Objective

The objective of the present study is to conduct a comparative analysis of the biomechanical advantages and disadvantages associated with a biplanar double support screw (BDSF) internal fixation device.

Methods

Two distinct femoral neck fracture models, one with a 30° angle and the other with a 70° angle, were created using a verified and effective finite element model. Accordingly, a total of eight groups of finite element models were utilized, each implanted with different configurations of fixation devices, including distal screw 150° BDSF, distal screw 165° BDSF, 3 CLS arranged in an inverted triangle configuration, and 4 CLS arranged in a "α" configuration. Subsequently, the displacement and distribution of Von Mises stress (VMS) in the femur and internal fixation device were assessed in each fracture group under an axial load of 2100 N.

Results

At Pauwels 30° Angle, the femur with a 150°-BDSF orientation exhibited a maximum displacement of 3.17 mm, while the femur with a 165°-BDSF orientation displayed a maximum displacement of 3.13 mm. When compared with the femoral neck fracture model characterized by a Pauwels Angle of 70°, the shear force observed in the 70° model was significantly higher than that in the 30° model. Conversely, the stability of the 30° model was significantly superior to that of the 70° model. Furthermore, in the 70° model, the BDSF group exhibited a maximum femur displacement that was lower than both the 3CCS (3.46 mm) and 4CCS (3.43 mm) thresholds.

Conclusion

The biomechanical properties of the BDSF internal fixation device are superior to the other two hollow screw internal fixation devices. Correspondingly, superior biomechanical outcomes can be achieved through the implementation of distal screw insertion at an angle of 165°. Thus, the BDSF internal fixation technique can be considered as a viable closed reduction internal fixation technique for managing femoral neck fractures at varying Pauwels angles.

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

OBJECTIVE

This study was performed to evaluate the mid-term clinical efficacy of the Femoral Neck System (FNS) (DePuy Synthes, Zuchwil, Switzerland) in treating young patients with unstable Pauwels type III femoral neck fractures.

METHODS

We performed a retrospective observational analysis of 21 young adults treated with the FNS. Clinical outcomes were assessed based on fracture reduction quality, Harris hip scores, and postoperative complication rates.

RESULTS

The study comprised 21 patients with a mean age of 35 years (range, 20-50 years) who were followed for a mean duration of 22.8 months (range, 16-30 months). Closed reduction was unfeasible in three (14.3%) patients, each of whom required open reduction. Notable postoperative complications were avascular necrosis in two (9.5%) patients, nonunion in one (4.7%), and implant failure in one (4.7%). Each of these complications led to the requirement for total hip arthroplasty.

CONCLUSION

The favorable mid-term clinical outcomes of this study indicate that the FNS is a potentially effective treatment modality for young individuals with unstable Pauwels type III femoral neck fractures.

High-energy Femoral Neck Fractures in Young Patients

Femoral neck fractures in physiologically young patients typically occur from high-energy axial loading forces through the thigh with the hip in an abducted position. These fractures have a high rate of associated head, chest, abdominal, and musculoskeletal injuries. High-energy hip fractures differ from traditional geriatric hip fractures regarding incidence, mechanism, management algorithms, and complications. After adequate resuscitation, goals of treatment include anatomic reduction and stable fixation while maintaining vascularity of the femoral head, which can be achieved through a variety of different techniques. Prompt recognition and treatment of these fractures is crucial to achieve a successful outcome because these injuries are often associated with complications such as osteonecrosis, fixation failure, and nonunion.

Biomechanical Stability of Femoral Neck System for Pauwels Type III Femoral Neck Fractures Based on Different Reduction Quality

To further investigate the biomechanics of a femoral neck system (FNS) for Pauwels type III femoral fractures based on three different reductions.We constructed three different reduction (anatomical reduction, negative buttress reduction, and positive buttress reduction) models of Pauwels type III femoral neck fractures. Then, three cannulated screws (3CS), dynamic hip screws (DHS), dynamic hip screws combined with an anti-rotation screw (DHS + ARS), one-hole femoral neck system (1HFNS), and two-hole femoral neck system (2HFNS) were assembled with the reduction models, respectively, to simulate the internal fixation surgical procedure. All models had a load of 2100 N in line with the femoral mechanical axis applied. The implant stress, the head and implant displacements, and the rotational angles of all models were recorded and analyzed.Compared to 3CS and 2HFNS, 1HFNS had higher implant stress (higher than 92.5 MPa and 46.3 MPa, respectively) and displacement (higher than 0.9 mm and 0.8 mm, respectively) in the anatomical reduction. 2HFNS exhibited the highest stress values (225.5 MPa) in the anatomical reduction but the lowest values (159.8 MPa) in the positive buttress reduction when compared to the other implants. 2HFNS showed the best rotational stability in the negative and positive buttress reduction (rotational angels of 0.8° and 0.6°, respectively).Based on the outcome of this computational study, it might be concluded that 2HFNS was an alternative fixation for the treatment of Pauwels type III femoral neck fracture, especially when anatomical reduction cannot be perfectly attained. More relevant clinical and biomechanical studies are needed in the future.

Does the angle between dynamic hip screw and anti-rotation screw affect the outcome of vertically oriented femoral neck fractures? A biomechanical analysis and clinical results

OBJECTIVE

To analyze the effects of the angle between dynamic hip screw (DHS) and anti-rotation screw (AS) on vertically oriented femoral neck fractures (VOFNFs) and investigate the clinical results of them.

METHODS

Eighteen synthetic femurs were simulated and divided into 3 groups. The angle between DHS and AS in anteroposterior-view was marked as α, and in lateral-view was marked as β, thus the total angle (TA) was defined as the summation of α and β. The groups were categorized as group A (TA ≤ 5°), B (5° < TA ≤ 10°), and C (TA > 10°), respectively. All samples were tested under incremental, cyclical loading, and loading to failure. In clinic, 80 consecutive VOFNFs in 78 patients were treated with DHS plus AS. The patients were divided into 2 groups, including 48 fractures in parallel group (TA ≤10°) and 32 in angular group (TA >10°).

RESULTS

Group A and B survived during incremental and cyclical loading and endured longer than group C. Axial stiffness and failure loads were not different between group A and B, and greater than group C. Fracture gaps compressive stress was highest in group A, followed by group B and C. Forty-one fractures in parallel group and 23 in angular group healed at final follow-up. Nonunion and osteonecrosis occurred in 3 and 4 of parallel group, and 4 and 5 of angular group.

CONCLUSION

The construction with TA ≤10° between DHS and AS showed superior biomechanical performance and clinical results than those with TA >10°.

Compressive buttress compared with off-axial screw fixation for vertical femoral neck fractures in young adults: a prospective, randomized controlled trial

BACKGROUND

To compare the clinical outcomes of compressive buttress screw (CBS) fixation, a novel screw fixation strategy, to off-axial screw fixation (off-axial partial threaded cannulated screw, OPTCS) for vertical femoral neck fractures (FNFs) in young adults.

METHODS

A total of 146 adults younger than 55 years old with high-energy Pauwels type III FNFs were randomized to receive CBS fixation or OPTCS fixation. Primary outcomes were complication rates, including fixation failure, fracture nonunion, and avascular necrosis of the femoral head (ANFH) at 24 months after treatment. Fixation loosening, femoral neck shortening and varus collapse, patient function and quality of life using the Harris hip score (HHS), and EuroQol-5 dimensional-5 levels (EQ-5D-5L) questionnaire (including EQ-5D-5L and EQ-VAS) were assessed as secondary outcomes at 24 months.

RESULTS

CBS and OPTCS fixation groups were similar with regard to demographics at baseline. At 24 months, patients in the CBS fixation cohort had a significantly lower rate of fixation failure (10.5% vs. 25.0%, p = 0.041) and fracture nonunion (1.8% vs. 18.3%, p = 0.003) compared with patients who received OPTCS fixation. There was no difference in rate of ANFH (7.0% vs. 11.7%, p = 0.389) between groups. Additionally, patients managed with CBS fixation showed significantly less fixation loosening (19.3% vs. 58.3%, p < 0.001), less severe femoral neck shortening and varus collapse (10.5% vs. 25.0%, p = 0.007), higher HHS (93 vs. 83, p = 0.001) and more excellent grade (68.4% vs. 36.7%, p = 0.008), higher EQ-5D-5L (0.814 vs, 0.581, p < 0.001) and EQ-VAS (85 vs. 80, p = 0.002).

CONCLUSION

CBS screw fixation confers significantly lower complication rate in addition to higher functional and quality of life outcomes for young adults with high-energy FNF compared with OPTCS fixation.

TRIAL REGISTRATION

This prospective, randomized controlled trial was approved by the institutional review board of our center, Ethics Committee of Shanghai sixth people's Hospital, and registered at www.chictr.org.cn (Approval Number: ChiCTR1900026283; Registered 29 September 2019-Retrospectively registered, https://www.chictr.org.cn/showproj.html?proj=43164 ).

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.

Surgical management of neck of femur fractures in patients younger than sixty-five years: a comparative study of three fixation methods

PURPOSE

Several surgical implants have been used for the treatment of neck of femur fracture (NOF) in younger patients such as dynamic hip screw (DHS) and cannulated compression screw. However, the superiority of one or another osteosynthesis device remains a matter of debate. The aim of this work is to evaluate and compare three fixation modalities: Cannulated Hip Screws (CHS), DHS and DHS associated to anti-rotating screw for surgical treatment of femoral neck fracture in young adults.

METHODS

It is a retrospective comparative study of three series of NOF fractures treated surgically over a period of ten years; including young adult patients (age > 18 years and < 65 years) treated conservatively using closed or open reduction and internal fixation. All types of NOF fractures according to Garden classification were included. Pathological, basi-cervical fractures and fractures on previously operated hips were excluded. The minimum follow-up recommended was two years. Clinical evaluation was based on the Postel Merle d'Aubigné score (PMA), the visual analogue scale (VAS), the Parker score, and the Hip Disability and Osteoarthritis Outcome Score (HOOS score). Reduction quality was assessed on X-rays.

RESULTS

Our series included 72 patients that were divided in three groups: Group A: Fixation using cannulated hip screws (33 patients). Group B: Fixation using DHS only (21 patients). Group C: Fixation using DHS associated to anti-rotation screw (18 patients). The patients of group A had better PMA and VAS scores, but there was no statistically significant difference. However, a significant difference (p=0.001) was found for the HOOS score. The fractures treated with DHS associated with anti-rotating screws, had the highest loss of reduction in the vertical axis (Yp) with the highest femoral head collapse (Zp) values. Group A had the lowest loss of reduction in the horizontal axis (Xp). There was no significant difference between the three methods of osteosynthesis in terms of loss of correction though.

CONCLUSION

We found comparable results in terms of healing and complication rates and loss of reduction for the three groups with no significant difference. However, the HOOS score was significantly better in the cannulated hip screw group.

The novel magnesium-titanium hybrid cannulated screws for the treatment of vertical femoral neck fractures: Biomechanical evaluation

Background

Conventional cannulated screws are commonly used for internal fixation in the treatment of vertical femoral neck fractures. However, the noticeably high rates of undesirable outcomes such as nonunion, malunion, avascular necrosis, and fixation failure still troubled the patients and surgeons. It is urgent to develop new cannulated screws to improve the above clinical problems. The purpose of this study was to design a novel magnesium-titanium hybrid cannulated screw and to further evaluate its biomechanical performance for the treatment of vertical femoral neck fractures.

Methods

A novel magnesium-titanium hybrid cannulated screw was designed, and the conventional titanium cannulated screw was also modeled. The finite element models for vertical femoral neck fractures with magnesium-titanium hybrid cannulated screws and conventional cannulated screws were respectively established. The hip joint contact force during walking gait calculated by a subject-specific musculoskeletal multibody dynamics model, was used as loads and boundary conditions for both finite element models. The stress and displacement distributions of the cannulated screws and the femur, the micromotion of the fracture surfaces of the femoral neck, and the overall stiffness were calculated and analyzed using finite element models. The biomechanical performance of the Magnesium-Titanium hybrid cannulated screws was evaluated.

Results

The maximum stresses of the magnesium-titanium hybrid cannulated screws and the conventional cannulated screws were 451.5 ​MPa and 476.8 ​MPa, respectively. The maximum stresses of the femur with the above different cannulated screws were 140.3 ​MPa and 164.8 ​MPa, respectively. The maximum displacement of the femur with the hybrid cannulated screws was 6.260 ​mm, lower than the femur with the conventional cannulated screws, which was 7.125 ​mm. The tangential micromotions in the two orthogonal directions at the fracture surface of the femoral neck with the magnesium-titanium hybrid cannulated screws were comparable to those with the conventional cannulated screws. The overall stiffness of the magnesium-titanium hybrid cannulated screw system was 490.17 ​N/mm, higher than that of the conventional cannulated screw system, which was 433.92 ​N/mm.

Conclusion

The magnesium-titanium hybrid cannulated screw had superior mechanical strength and fixation stability for the treatment of the vertical femoral neck fractures, compared with those of the conventional cannulated screw, indicating that the magnesium-titanium hybrid cannulated screw has great potential as a new fixation strategy in future clinical applications.The translational potential of this article: This study highlights an innovative design of the magnesium-titanium hybrid cannulated screw for the treatment of vertical femoral neck fractures. The novel magnesium-titanium hybrid cannulated screw not only to provide sufficient mechanical strength and fixation stability but also to contribute to the promotion of fracture healing, which could provide a better treatment for the vertical femoral neck fractures, beneficially reducing the incidence of nonunion and reoperation rates.

Fibula allograft with cannulated screw fixation versus ordinary cannulated screw fixation for femoral neck fractures: a 10-year retrospective comparative study

BACKGROUND

For femoral neck fractures in young and middle-aged patients, both fibula allograft with cannulated screw fixation and ordinary cannulated screw fixation are clinically effective treatments. However, for unstable femoral neck fractures, ordinary cannulated screw fixation is characterized by a high risk of postoperative complications and a high rate of mechanical failure after internal fixation. For this study, we systematically compared the long-term efficacy and postoperative complications of these two procedures.

METHODS

A total of 156 subjects diagnosed as femoral neck fractures participated in our study. Subjects in the combination group underwent fibula allograft with cannulated screw fixation (n = 76), and those in the control group were treated with ordinary cannulated screw fixation (n = 80). Baseline characteristics, perioperative outcomes, Harris hip score (HHS) and EuroQoL five-dimension questionnaire (EQ-5D); and the incidence of postoperative and bone healing complications in the two groups were recorded and compared.

RESULTS

The average follow-up time was more than 10 years. Intra-operative blood loss significantly increased in the combination group compared with the control group (P < 0.05). There were significantly improved performances in healing time, the time course of recovery of full-weight-bearing stepping, HHS and EQ-5D scores in the combination group compared with the control group (P < 0.05). Besides, the incidence rates of femoral head necrosis, nonunion, femoral neck shortening and total hip replacement were significantly lower in the combination group than those in the control group (P < 0.05).

CONCLUSION

Fibula allograft with cannulated screw fixation shows a better long-term therapeutic effect than ordinary cannulated screw fixation for femoral neck fractures in young and middle-aged patients. Patients receiving the combination strategy have faster and high-quality functional recovery after femoral neck fractures and a lower incidence rate of postoperative complications.

Open Fracture of the Femoral Neck in an Adult: Case Report and Surgical Solution

Intracapsular proximal femoral fracture is a frequent injury in elderly patients, often associated with low-energy trauma and reduced bone mass. In young patient, it is uncommon, usually caused by high-energy trauma and accompanied by damage to the adjacent soft tissues. However, reports of open intracapsular proximal femoral fracture due to indirect trauma are rare in the orthopedic literature. In the present article, we describe a case of this injury in a 35-year-old man involved in a car accident. The proximal femur was exposed at the gluteal region due to a mechanism similar to dislocation of the posterior hip. We describe the initial treatment and subsequent management until achieving a definitive solution using total hip arthroplasty and muscle transfer to reconstruct the abductor mechanism of the hip. At 10 months of follow-up, the patient presented good functional outcome, with gradual recovery of the abductive strength and a Harris Hip Score of 91 points. In addition, a radiographic study showed that the cemented total prosthesis was well-positioned. This therapeutic strategy (total hip arthroplasty with muscle transfer to reconstruct the abductor musculature) was successful to treat an intracapsular proximal femoral fracture with bone exposure.

Femoral neck system and cannulated compression screws in the treatment of non-anatomical reduction Pauwels type-III femoral neck fractures: A finite element analysis

BACKGROUND

High shear force is a major factor detrimental to the healing of vertical femoral neck fractures. In addition to firm fixation, reduction quality is crucial for postoperative stability. The present study aimed to compare the biomechanical stability of the newly invented femoral neck system and three inverted-triangle cannulated compression screws treatments for non-anatomical reduction of Pauwels type-III femoral neck fractures.

METHODS

A total of 18 non-anatomical reduction Pauwels type-III femoral neck fracture finite element models were fabricated and fixed using three inverted-triangle cannulated compression screws or the femoral neck system. A 1950-N force was applied to the femoral head to simulate the physiological load during a single-leg stance. Parameters of the maximum total deformation, the interfragmentary gap, and the maximum von Mises stress of the implants and the proximal femur were analyzed.

FINDINGS

The results of the maximum total deformation, interfragmentary gap, and maximum von Mises stress of the implants in the negative-negative buttress model fixed by the femoral neck system were the largest among all groups (3.58 mm, 0.252 mm, and 729.68 MPa, respectively). In contrast, the anatomical-anatomical reduction model fixed by three inverted-triangle cannulated compression screws demonstrated the minimum total deformation, interfragmentary gap, and minimum von Mises stress of implants (1.107 mm, 0.09 mm, and 189.83 MPa, respectively).

INTERPRETATION

Anatomical reduction or positive buttress in femoral neck fractures should be recommended during fracture reduction. The femoral neck system showed weaker biomechanical stability than three inverted-triangle cannulated compression screws in treating Pauwels type-III femoral neck fractures.

Reliability of Modified Pauwels Angle in Preoperative Plain X-ray and Intraoperative Fluoroscope in Young Femoral Neck Fracture Fixation

Purpose

This research aims to evaluate the reliability of modified Pauwels angle in preoperative plain X-ray and intraoperative fluoroscope.

Method

This study included 48 male and 18 female patients with an average age of 36.95 years. Seven observers contributed to this study by measuring the modified Pauwels types and angles on 66 anterior-posterior (AP) views from preoperative radiographs and intraoperative fluorography. Intra-observer and inter-observer reliability was calculated using Fleiss's kappa and intraclass correlation coefficient (ICC).

Results

The results showed that the intra-observer reliability for the modified Pauwels type using Kappa coefficient in preoperative and intraoperative assessments was 0.584 and 0.823, respectively. The inter-observer reliability for preoperative and intraoperative evaluations was 0.467 and 0.753 for all observers, 0.647 and 0.783 for specialized trauma orthopedists, and 0.41 and 0.752 for the residents. The modified Pauwels angle assessment in intra-observers using ICC was 0.804 preoperatively and 0.943 intraoperatively. The inter-observer for preoperative and intraoperative assessments was 0.675 and 0.834 for all observers, 0.977 and 0.982 for specialized trauma orthopedists, and 0.622 and 0.823 for residents. The difference between preoperative and intraoperative modified Pauwels angles was 9.75 ± 6.76 (p < 0.05). Eleven patients had their modified Pauwels type changed, which altered the implant selection in 8 patients.

Conclusion

The modified Pauwels angle together with type assessment has excellent reliability for implant selection when implemented intraoperatively, and at least two specialized trauma orthopedists should evaluate the fracture lines.

Pre-sliding of femoral neck system improves fixation stability in pauwels type III femoral neck fracture: a finite element analysis

BACKGROUND

Femoral neck fractures are a common injury in older adults and their management presents a significant challenge for orthopedic surgeons. The Femoral Neck System (FNS) was recently introduced for the fixation of femur neck fractures. Although neck shortening was reduced with the FNS, the complication rates were not reduced. Thus, improvements to enhance fixation stability should be made for the FNS. We hypothesized that (1) the pre-sliding technique and (2) the use of longer anti-rotation screw would increase fracture stability. This study aimed to determine the change in fracture stability using the pre-sliding technique and long anti-rotation screw in the FNS for fixation of Pauwels type III femoral neck fractures.

METHODS

Finite element models of Pauwels type III femoral neck fracture fixed with pre-sliding FNS and 5-mm longer anti-rotation screw were established. The models were subjected to normal walking load. The material properties of the elements belonging to the bone were mapped by assigning the formulation with the computed tomography Hounsfield unit.

RESULTS

Pauwels type III femoral neck fractures fixed with pre-slided FNS showed better fracture stability, decreasing fracture gap and sliding by 14% and 12%, respectively, under normal walking load. No element of cortical bone in any of the models had an absolute value of principal strain that exceeded 1%. The peak von Mises stress (VMS) of the implants ranged from 260 to 289 MPa, and the highest peak VMS value was 50% lower than the yield strength of the titanium alloy (800 MPa). The longer anti-rotation screw did not affect fracture stability.

CONCLUSIONS

The pre-sliding technique using the FNS showed higher fracture stability than the standard fixation technique for a Pauwels type III femoral neck fracture. The longer anti-rotation screw did not contribute significantly to fixation stability. As this finite element analysis considered the inhomogeneous mechanical property of the bone, it offered equivalent mechanical conditions to investigate the components of interest.

Trajectory of bolt and length of plate in femoral neck system determine the stability of femur neck fracture and risk of subsequent subtrochanteric fracture : a finite element analysis

BACKGROUND

This study aimed to analyze the differences in the stability of fractures, stress distribution around the distal-most screw according to the length of the plate and the trajectory of the bolt in Pauwels type III femoral neck fracture using the femoral neck system (FNS).

METHODS

Finite element models of Pauwels type III femoral neck fractures were established with surgical variations in the trajectory of the bolt (central, inferior, valgus, and varus) and length of the lateral plate (1- and 2-hole plate). The models were subsequently subjected to normal walking and stair-climbing loads.

RESULTS

The screw-holding cortical bone in subtrochanter in the model with a 2-hole plate and the bolt in the inferior trajectory and the models with 1-hole or 2-hole plate and the bolt in valgus trajectory had shown greater maximum principal strain than the models with central or varus trajectories. The gap and sliding distance on the fracture surface were larger with inferior or varus trajectories of the bolt and smaller with the valgus trajectory of the bolt under both loads, compared to those of the central trajectory.

CONCLUSION

For the fixation of Pauwels type III femoral neck fracture, the trajectory of the FNS bolt and the length of the plate affect the mechanical stability of the fracture and the strain of cortical bone around the distal-most screw. The surgical target should stay on the central trajectory of the bolt and the 2-hole plate's mechanical benefits did not exceed the risk.

Total hip arthroplasty for failed internal fixation of femoral neck fracture: a retrospective study with 2-14 years' follow-up of 345 patients

OBJECTIVES

The purpose of this study was to analyze mid- to long-term outcomes of total hip arthroplasty (THA) following failed internal fixation of femoral neck fracture.

METHODS

This study retrospectively analyzed 345 patients with femoral neck fracture who underwent THA after failure of internal fixation at our hospital between January, 2003 and December, 2019. Patients older than 55 years (n = 175) and patients no older than 55 years (n = 170) were compared in terms of complications and survival rates during follow-up, which lasted a mean of 6 years.

RESULTS

The two age groups showed similarly low incidence of complications and similarly long periods of survival without revision surgery. Only three younger patients and two older patients underwent revision surgery during follow-up. The two groups showed similarly high survival rates at the end of follow-up (> 93%). Younger patients showed significantly bettter Harris hip score at last follow-up (90.2 vs. 88.1 points, p < 0.001) without clinically significant difference, but they required THA significantly earlier after internal fixation (4.4 vs. 6.8 years, p < 0.001).

CONCLUSIONS

THA after failed internal fixation of femoral neck fracture is a well tolerated and effective procedure in older and younger patients.

Biomechanical effects of internal fixation with self-lock compression anti-rotation blade for Pauwels type III femoral neck fractures: a comparative finite element analysis

BACKGROUND

Self-lock compression anti-rotation blade (SCAB) is a novel internal fixation implant for femoral neck fractures (FNF). We conducted this finite element analysis study to evaluate the biomechanical performances of SCAB combined with a cannulated screw for fixation of Pauwels type III FNF.

METHODS

Three finite element models of Pauwels type III FNF treated with various internal fixations were established: a: the inverted triangular parallel cannulated screw (3CS) model, b: the biplane double-supported screw fixation (BDSF) model, c: the SCAB combined with a cannulated screw model. Displacement and Von Mises stress of femurs and internal fixations under increasing loads as well as the average stress on fracture surfaces and maximum displacements on the X and Z axis of proximal fracture fragments at maximum load were measured and compared.

RESULT

The SCAB-based internal fixation exhibited superior biomechanical performances compared with 3CS and BDSF configurations, as the former resulted in lower parameters including displacement of the femur, Von Mises stress of internal fixation, stress on fracture surfaces as well as X and Z axis displacement of fracture fragments.

CONCLUSION

Internal fixation using SCAB combined with a cannulated screw for Pauwels type III FNFs shows enough stability, with satisfied resistance to varus and shearing forces, which may provide a new option for the treatment of FNFs.

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.

Comparative Study for Osteosynthesis of Femoral Neck Fractures: Cannulated Screws versus Femoral Neck System

Purpose

The purpose of this study is to compare the radiological results of fixation using the femoral neck system (FNS) and cannulated screw (CS) for treatment of femoral neck fractures.

Materials and Methods

A retrospective study of patients with femoral neck fractures who underwent internal fixation and had follow-up of more than six months from 2010 to 2020 was conducted. A total of 87 patients were enrolled in the study. The FNS group included 20 patients and the CS group included 67 patients. Classification of fractures was performed according to Garden and Pauwels classification. Operation time, intraoperative blood loss, sliding distance of the implant, lateral soft tissue irritation caused by implants, and complications were evaluated.

Results

The mean operation time was 40.30 minutes in the FNS group and 46.84 minutes in the CS group. The mean intraoperative bleeding volume was 51.25 mL in the FNS group and 72.16 mL in the CS group. Bone union was achieved in 18 patients in the FNS group (90.0%) and in 61 patients in the CS group (91.0%). The mean sliding distance of the implant was 4.06 mm in the FNS group and 3.92 mm in the CS group. No patients in the FNS group and 12 patients in the CS group complained of soft tissue irritation.

Conclusion

A shorter operative time, less intraoperative bleeding, and less irritation of soft tissue were observed in the FNS group. FNS could be an alternative to CS for fixation of femoral neck fractures.

Comparison of femoral neck system vs. dynamic hip system blade for the treatment of femoral neck fracture in young patients: A retrospective study

Background

Femoral neck fracture is a common fracture in orthopedic practice. This study aimed to compare the clinical outcomes between the femoral neck system and dynamic hip system blade for the treatment of femoral neck fracture in young patients.

Methods

This retrospective study included 43 and 52 patients who underwent treatment for femoral neck fracture with the femoral neck system and dynamic hip system blade, respectively, between August 2019 and August 2020. Operative indexes, including operation duration, blood loss, incision length, postoperative complications (femoral neck shortening, non-union, screw pull-out, femoral head necrosis), and Harris scale scores were recorded and analyzed.

Results

Compared to that with the dynamic hip system blade, the femoral neck system showed significantly less operation duration (femoral neck system vs. dynamic hip system blade: 47.09 ± 9.19 vs. 52.90 ± 9.64, P = 0.004), less blood loss (48.53 ± 10.69 vs. 65.31 ± 17.91, P < 0.001), and shorter incision length (4.04 ± 0.43 vs. 4.93 ± 0.53, P < 0.001). Femoral neck shortening was significantly lower with the femoral neck system than with the dynamic hip system blade (3.93 ± 2.40, n = 39 vs. 5.22 ± 2.89, n = 44, P = 0.031). No statistical differences were observed between the two groups in nonunion, screw pull-out, and femoral head necrosis. In addition, the latest follow-up Harris scale score was significantly higher with the femoral neck system than with the dynamic hip system blade (92.3 ± 4.5 vs. 89. 9 ± 4.9, P = 0.015).

Conclusion

The femoral neck system results in less trauma, less femoral neck shortening, and better hip joint function than the dynamic hip system blade for the treatment of femoral neck fracture in young patients.

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.

Biomechanical study of internal fixation methods for femoral neck fractures based on Pauwels angle

Objective: To select the most appropriate internal fixation method based on the Pauwels angle, in order to provide a new concept for clinical accurate treatment of femoral neck fractures (FNFs). Methods: FNFs models of Pauwels 30 ° ; 40 ° ; 50 ° ; 60 ° were created respectively. For Pauwels ≤ 50 ° , 1, 2 and 3 Cannulated Compression Screws (CCS) and Porous Tantalum Screws (PTS) were used to fix the fracture for the models. For Pauwels 60 ° , 3CCS and Medial Buttress Plate (MBP) combined with 1, 2 and 3CCS were used to fix the fracture. Based on the results of the finite element (FE) analysis, the biomechanical properties of each model were compared by analyzing and evaluating the following four parameters: maximal stress of the bone (MBS), maximal stress of the implants (MIS), maximal displacement of bone (MBD), interfragmentary motion (IFM). Results: At Pauwels 30 ° , the larger parameters were found in 1CCS, which was 94.8 MPa (MBS), 307.7 MPa (MIS), 0.86 mm (MBD) and 0.36 mm (IFM). In 2CCS group, the parameters were 86.1 MPa (MBS), 254.4 MPa (MIS), 0.73 mm (MBD) and 0.27 mm (IFM), which were similar to those of PTS. At Pauwels 40 ° ; 50 ° , with the increase of the number of used CCS, accordingly, the parameters decreased. Particularly, the MIS (Pauwels 50 ° ) of 1CCS was 1,195.3 MPa, but the other were less than the yield range of the materials. At Pauwels 60 ° , the MBS of 3CCS group was 128.6 Mpa, which had the risk of failure. In 2CCS + MBP group, the parameters were 124.2 MPa (MBS), 602.5 MPa (MIS), 0.75 mm (MBD) and 0.48 mm (IFM), The model stability was significantly enhanced after adding MBP. Conclusion: Pauwels type Ⅰ (< 30 ° ) fractures can reduce the number of CCS, and PTS is an appropriate alternative treatment. For Pauwels type Ⅱ fractures ( 30 ° ∼ 50 ° ), the 3CCS fixation method is still recommended. For Pauwels type Ⅲ fractures (> 50 ° ), it is recommended to add MBP to the medial femoral neck and combine with 2CCS to establish a satisfactory fracture healing environment.

Combined Deflection Angle Classification: A Novel Typing System of Adult Femoral Neck Fracture

OBJECTIVE

Femoral neck fracture (FNF) is a common clinical trauma with high mortality and disability rates. Furthermore, its incidence increases exponentially with increasing age. Existing classifications have some disadvantages. Thus, this study aimed to establish a novel typing system for FNF.

METHODS

We retrospectively analyzed all adult patients with FNF admitted to our hospital between December 2015 and November 2017 for cannulated screw internal fixation. The study population was divided into the femoral varus offset group (VAR) and the valgus offset group (VAL). The data collected included sex, age, affected side, injury mode, body mass index, complications, pelvic incidence (PI), hip deflection angle (HDA), combined deflection angle (CDA), and neck shaft angle. Statistical analysis was conducted to determine the correlation between complications and deviation angles. A novel typing system was developed and compared with the Garden classification to detect its superiority.

RESULTS

A total of 108 patients were recruited, with 59 patients in the VAR and 49 patients in the VAL groups. The incidence of complications in the VAR group was significantly higher than that in the VAL group (P < 0.05). Moreover, there were more male participants in the VAR group. Compared with the VAL group, the VAR group had significantly higher PI, HDA, and CDA (P < 0.05). The CDA classification (CDAC) was defined, with CDA as the main criterion and HDA as the supplementary criterion. Furthermore, there was a hierarchical correlation between the actual incidence of complications and the typing level, which was increased in CDAC but not in the Garden classification. This showed that CDAC was more accurate.

CONCLUSION

A novel typing system, CDAC, for FNF was established, which was more accurate than the Garden classification. We suggest combining CDAC and Garden classifications for the preoperative diagnosis, treatment selection, and prognostic evaluation for patients with FNF.

The incidence of focal osteonecrosis of the femoral head and its impact on conversion hip arthroplasty after screw fixation of femoral neck fractures: a multicenter retrospective study based on postoperative magnetic resonance imaging

PURPOSE

Osteonecrosis of the femoral head (ONFH) and subsequent head collapse is a major concern after internal fixation of femoral neck fracture (FNF). Previous studies focused on ONFH incidence using plain radiography; postoperative magnetic resonance imaging (MRI) was rarely performed. We performed a multicenter retrospective study to investigate the incidence of ONFH and the need for conversion hip arthroplasty after FNF screw fixation.

METHODS

We reviewed 195 patients who underwent screw fixation during closed FNF reduction between 2012 and 2017 at three institutions. Except for patients who did not consent to MRI, all patients underwent postoperative MRI either 1-3 years after screw fixation. The occurrence of ONFH was investigated through plain radiography and MRI.

RESULTS

Thirty patients were diagnosed with ONFH through plain radiography, and an additional 33 patients were diagnosed with MRI, resulting in a total of 63 patients (32.3%) diagnosed with ONFH. The mean time to ONFH diagnosis was 18.9 months and the conversion rate to hip arthroplasty was 10.2%. Of the 33 patients who were normal on hip radiography but exhibited ONFH on MRI, all had small focal lesions not associated with head collapse at the last follow-up. The ONFH group diagnosed through plain radiography had more unstable FNFs than the group diagnosed through MRI.

CONCLUSION

Although postoperative MRI revealed a higher incidence of ONFH after FNF screw fixation than reported previously, the small focal MRI lesions were not associated with increased risks of femoral head collapse or conversion to arthroplasty.

Finite element comparative analysis of three different internal fixation methods in the treatment of Pauwels type III femoral neck fractures

BACKGROUND

Comparison of 4 cannulated lag screws (3 inverted triangular cannulated screws + anti-rotating screws;4 CLS), dynamic hip screws + derotational screws (DHS + DS), and femoral neck fixation system (FNS) in the treatment of Biomechanical properties of middle-aged Pauwels type III femoral neck fractures.

METHODS

The femur CT data of a healthy young volunteer was selected and imported into Mimics software to construct a three-dimensional model of a normal femur. Pauwels type III femoral neck fractures were simulated according to the 70° fracture line. Use Geomagic and SolidWorks software to optimize and build CLS, DHS + DS, and FNS fracture internal fixation models. Finally, Ansys software was used to analyze the stress distribution, peak value, and maximum displacement of the proximal fracture fragment and internal fixation; the displacement distribution, and peak value of the fracture surface at the fracture end.

RESULTS

① The stress peaks of the proximal fracture fragments in the three groups were concentrated near the femoral calcar. The peak stress of the FNS group was the largest, and the DHS + DS group was the smallest. ②The displacement of the fracture fragments was all located at the top of the femur. The peak displacement of the FNS group was the largest, and the DHS + DS group was the smallest. ③ The internal fixation stress of the three groups is concentrated in the middle part of the device. The stress distribution of the first two groups of models is more uniform than that of FNS. The peak stress of FNS is the largest and the CLS is the smallest. ④ The internal fixed displacements are all located at the top of the model. The peak displacement of the CLS is the largest, and the DHS + DS is the smallest. ⑤ The displacement of the fracture surface is in the upper part of the fractured end. The peak displacement of the FNS group was the largest, and the DHS + DS group was the smallest.

CONCLUSION

Compared with the other two internal fixation methods, dynamic hip screw + derotational screw (DHS + DS) showed good biomechanical stability. When Pauwels type III femoral neck fracture occurs in young adults, DHS + DS can be given priority as the preferred treatment for this type of fracture.

Internal Fixation of Garden Type III Femoral Neck Fractures with Sliding Hip Screw and Anti-Rotation Screw: Does Increased Valgus Improve Healing?

Background and Objectives: The aim of this study was to compare the effect of valgus versus anatomic reduction on internal fixation of Garden type III femoral neck fractures using the sliding hip screw (SHS) and anti-rotation screw (ARS) regarding the radiographic and therapeutic outcome. Patients and Methods: A retrospective case-controlled study was performed in a level I trauma center. All patients between 2006 and 2020 aged younger than 70 years with a Garden type III femoral neck fracture and a Kellgren-Lawrence score under grade III stabilized using SHS and ARS were identified. One-hundred and nine patients were included, with a group distribution of sixty-eight patients in group A (anatomic reduction) and forty-one patients in group B (valgus reduction). Results: Mean age was 55 years, and the mean Kellgren-Lawrence score was 1 in both groups. Mean femoral neck angle was 130.5 ± 3.8° in group A and 142.8 ± 4.3° in group B (p = 0.001), with an over-correction of 12° in group B. Tip-apex distance was 10.0 ± 2.8 mm in group A versus 9.3 ± 2.8 mm in group B (p = 0.89). Healing time was 9 weeks in group A compared to 12 weeks in group B (p = 0.001). Failure rate was 4.4% in group A and 17.1% in group B (p = 0.027). Conclusions: Anatomic reduction of Garden type III femoral neck fractures in patients younger than 70 years treated using SHS and ARS resulted in significantly lower failure rates and shorter healing times than after valgus reduction. Therefore, it can be recommended to achieve anatomic reduction.

Reoperation for sliding hip screws vs cannulated cancellous screws in femoral neck fractures: A study from the Danish Fracture Database Collaborators

INTRODUCTION

It is still debated whether to use cannulated cancellous screw (CCS) or sliding hip screw (SHS) implants for femoral neck fracture (FNF) patients but there are no studies large enough to evaluate on smaller differences. The aim were to compare the reoperation and mortality rates of a large cohort of FNF patients above 60 years of age with internal fixation using CCS and SHS implants, with stratification by fracture classification.

METHODS

This register study employed prospectively collected data from 2014 to 2018 from the Danish Fracture Database, including 2-year follow-up and data on age, sex, surgery, comorbidity and fracture classification. Reoperation data was retrieved from the Danish National Patient Register. The primary outcome was major reoperation, defined as re-osteosynthesis, conversion to arthroplasty, non-union surgery, Girdlestone procedure or deep infection 1-year post-surgery. Relative risk (RR) for the CCS group compared with the SHS group was estimated using Cox proportional hazards modelling, adjusted for age, sex and comorbidity (including 95% confidence intervals).

RESULTS

A total of 2,598 FNFs were included, 1,731 with CCS (67%) and 867 with SHS (33%). The overall 1-year major reoperation rate was 15% with CCS and 13% with SHS, yielding an adjusted RR of 1.10 (0.88; 1.37) for CCS compared to SHS. The adjusted RR was 1.15 (0.77; 1.69) for undisplaced FNF, 1.09 (0.68; 1.75) for displaced FNF and 1.35 (0.94; 1.94) for transcervical FNF, which increased to 1.42 (1.01; 2.00) after 2 years. The minor reoperation rate was higher for CCS (3%) than SHS (1%), yielding an adjusted RR of 2.28 (1.14; 4.51). The adjusted RR for CCS compared to SHS was 0.83 (0.62; 1.12) for 30-day mortality and 0.96 (0.82; 1.14) for 1-year mortality.

CONCLUSIONS

We found no difference between CCS and SHS in major reoperation rates; however, for transcervical FNF, CCS was associated with higher reoperation rates. Furthermore, CCS was associated with a higher risk of minor reoperation than SHS. There were no differences in mortality rates.

Comparison of daytime and after-hours surgical treatment of femoral neck fractures

Background

The timing of surgery for femoral neck fractures in young adults remains controversial. Nonetheless, the debate continues about whether orthopedic trauma cases should be operated daytime or after hours.

Aim

This study compared the clinical and radiological outcomes of surgery on femoral neck fractures during daytime versus after-hours.

Patients and Methods

A total of 124 patients aged 18-60 years who were operated for femoral neck fractures between 2015 and 2020 were included in the study. The patients were separated into two groups. Seventy-two patients operated between 08:00 and 17:00 hours were defined as the daytime group and 52 patients operated between 17:01 and 07:59 hours were defined as the after-hours group. Demographic data, reduction quality, duration of operation, intraoperative estimated blood loss (EBL), postoperative complications, revision rates, and postoperative Harris hip score results of the two groups were recorded for analysis.

Results

There was no significant difference between the groups in terms of age, gender, body mass index, smoking, fracture type and follow-up time, reduction quality, postoperative complication rates, revision rates, and Harris hip score results. Waiting times until surgery, operation duration, and intraoperative EBL amounts were, in the daytime group, significantly higher than in the after-hours group.

Conclusion

In this study comparing femoral neck fractures operated on daytime and after-hours in adults, the waiting time until surgery was found to be higher in the daytime group. Operation duration and EBL were higher in the after-hours group.

Biomechanical evaluation of different internal fixation methods based on finite element analysis for Pauwels type III femoral neck fracture

BACKGROUND AND OBJECTIVE

The best internal fixation method for the treatment of Pauwels type III femoral neck fractures (FNFs) remains to be demonstrated. Through finite element analysis, this study explored whether dynamic hip screw (DHS) combined with anti rotation screw or medial buttress plate can improve the stability of internal fixation, and the femoral neck system (FNS) with similar structure to DHS and the traditional cannulated screw (CSs) were added for comparison. To evaluate their respective biomechanical advantages and disadvantages in the treatment of Pauwels type III FNFs.

METHODS

Six groups of internal fixation models for the treatment of FNFs were established, including CSs, DHS, DHS combined with single anti-rotation screw (DHS + SS), and DHS combined with both anti-rotation screw (DHS + BS), DHS combined with medial buttress plate (DHS + MBP), new femoral neck internal fixation system (Femoral Neck System, FNS). Four finite element analysis models were established for each group, evaluation of femoral displacement and internal fixation stress during stair climbing and walking conditions, and the contact force of the hip joint was used in two cases, dynamic and static.

RESULTS

The fracture plane motion and peak stress of internal fixators were the lowest with DHS + BS and CSs fixation, and the two results are very close, The peak value of DHS combined with anti rotation screw or medial buttress plate is much lower than that of DHS, indicating that the fixation effect of the combined model is enhanced, and there is no significant difference between FNS and DHS + SS.

CONCLUSION

Both the anti rotation screw and medial buttress plate can effectively reduce the movement of fracture section and share the shear force of DHS, FNS has the similar fixation stability to DHS + SS, DHS + BS has the biomechanical advantages of significantly reducing the risk of internal fixation failure and femoral yield. Therefore, the use of DHS + BS may be a more favorable choice in the case of Pauwels type III FNFs with higher fixation requirements.

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).

Biplane double supported screw fixation for femoral neck fracture in young adults: A prospective cohort study

Introduction

Achieving accurate anatomic reduction and stable internal fixation is mandatory in the management of femoral neck fractures (FNF) in adults. The spatial configuration and direction of the screws have been reported to provide stability to the fracture. The study's goal is to analyse the clinico-radiological outcome of the newer biplane double-supported screw fixation (BDSF) technique in the Indian cohort.

Materials and methods

Patients with isolated FNFs underwent osteo-synthesis by BDSF technique. Radiological outcome was evaluated by time to union and fracture healing on plain radiographs. Clinical outcome was measured using the Harris hip score (HHS) at 1, 3, 6, and 12 months after surgery. The pain reduction was measured using the VAS score.

Results

Twenty-seven patients with a mean age of 37.33 ± 9.84 years (24-55 years) were followed up for at least 12 months (12-31 months). The mean HHS at 12 months was 94.81 ± 8.18 (range: 68-100). Twenty-five patients were able to achieve radiological union within a mean time of 14.60 ± 4.69 weeks (range: 8-28). The overall complication rate was found to be 18.51% (5 out of 27 patients). Individual complications were non-union (2 patients; 7.4%), AVN (3 patients; 11.11%), and screw back out with femoral neck shortening (4 patients; 14.81%).

Conclusion

Screw configuration using the BDSF technique provides a good union rate with minimum complications. The majority of patients resulted in a good (HHS >80) to excellent functional outcome. Based on the clinico-radiological outcome obtained, we conclude that this technique is effective in the fixation of FNF in adults.

Level of study

Level II.

A quantitative study of bone defects in displaced femoral neck fractures based on virtual reduction techniques

BACKGROUND

Bone defects in femoral neck fractures are strongly associated with the prognosis after internal fixation. However, qualitative analysis of bone defects in femoral neck fractures has already been performed, quantitative studies have not been reported. In this study, we aimed to systematically analyse the morphological characteristics of bone defects in patients with femoral neck fractures using computed tomography (CT) images combined with computer image analysis techniques.

METHODS

Four hundred and sixty-nine patients with femoral neck fractures from January 2014 to December 2018 at two grade A tertiary hospitals were included. Models were created in Mimics software based on CT images collected within 1 week after injury and then imported into 3-matic software for virtual reduction. The volume of the bone defect (VBD), maximum defect thickness (MDT), extent of the bone defect region (EBDR) , main defect quadrant (MDQ), collapse type and fracture classification were calculated and recorded.

RESULTS

The EBDR, collapse type and MDT all had a significant positive effect on the VBD (P <0.05), with a more significant effect at higher quantiles. Age also had a significant positive effect on the VBD (P < 0.05), but its effect was more pronounced at lower quantiles. Compared to non-subcapital fractures, subcapital fractures had a positive effect on the VBD only at the 50 and 75% quantiles (P < 0.01). The female sex had a significant negative effect on the VBD compared to the male sex (P < 0.05).

CONCLUSION

This study established a reliable computer image processing method for quantitative analysis of the VBD in femoral neck fractures and revealed that all patients with femoral neck fractures had bone defects, which can occur at any part of the femoral neck. The EBDR, MDT, collapse type, and patient age and sex were all important risk factors for the extent of the defect and should be taken into account in surgical planning.

Treatment Failure in Femoral Neck Fractures in Adults Less Than 50 Years of Age: Analysis of 492 Patients Repaired at 26 North American Trauma Centers

OBJECTIVES

To assess the operative results of femoral neck fractures (FNFs) in young adults in a large multicenter series, specifically focusing on risk factors for treatment failure.

DESIGN

Large multicenter retrospective cohort series.

SETTING

Twenty-six North American Level 1 trauma centers.

PATIENTS

Skeletally mature patients younger than 50 years with displaced and nondisplaced FNFs treated between 2005 and 2017.

INTERVENTION

Operative repair of FNF.

MAIN OUTCOME MEASUREMENTS

The main outcome measure is treatment failure: nonunion and/or failed fixation, osteonecrosis, malunion, and need for subsequent major reconstructive surgery (arthroplasty or proximal femoral osteotomy). Logistic regression models were conducted to examine factors associated with treatment failure.

RESULTS

Of 492 patients with FNFs studied, a major complication and/or subsequent major reconstructive surgery occurred in 45% (52% of 377 displaced fractures and 21% of 115 nondisplaced fractures). Overall, 23% of patients had nonunion/failure of fixation, 12% osteonecrosis type 2b or worse, 15% malunion (>10 mm), and 32% required major reconstructive surgery. Odds of failure were increased with fair-to-poor reduction [odds ratio (OR) = 5.29, 95% confidence interval (CI) = 2.41-13.31], chronic alcohol misuse (OR = 3.08, 95% CI = 1.59-6.38), comminution (OR = 2.63, 95% CI = 1.69-4.13), multiple screw constructs (vs. fixed-angle devices, OR = 1.95, 95% CI = 1.30-2.95), metabolic bone disease (OR = 1.77, 95% CI = 1.17-2.67), and increasing age (OR = 1.03, 95% CI = 1.01-1.06). Women (OR = 0.57, 95% CI = 0.37-0.88), Pauwels angle ≤50 degrees (type 1 or 2; OR = 0.64, 95% CI = 0.41-0.98), or associated femoral shaft fracture (OR = 0.19, 95% CI = 0.10-0.33) had lower odds of failure.

CONCLUSIONS

FNFs in adults <50 years old remain a difficult clinical and surgical problem, with 45% of patients experiencing major complications and 32% undergoing subsequent major reconstructive surgery. Risk factors for complications after treatment of displaced FNFs were numerous.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.