Fixation effects of different types of cannulated screws on vertical femoral neck fracture: A finite element analysis and experimental study

Comparison of rehabilitation outcomes between robot-assisted and freehand screw placement in treatment of femoral neck fractures: a systematic review and meta-analysis

PURPOSE

To compare the postoperative rehabilitation of femoral neck fractures treated with robot-assisted nailing and freehand nailing.

METHODS

We systematically searched the PubMed, EMBASE, Cochrane, China National Knowledge Infrastructure(CNKI), WanFang database, China Science and Technology Journal Database (VIP) and Web of Science databases to identify potentially eligible articles. Indispensable data such as the year of publication, country, study type, robot type, age, number of patients, sex distribution, study design, and outcome indicators were extracted. The outcome indicators of interest included healing rate, length of healing time, Harris score, operation time, frequency of X-ray fluoroscopy, frequency of guide pin insertion, and intraoperative blood loss. RevMan 5.4.1 was used for the meta-analysis.

RESULTS

Fourteen studies with 908 participants were included in this meta-analysis. The results showed that in terms of healing rate (SMD = 2.75, 95% CI, 1.03 to 7.32, P = 0.04) and Harris score (SMD = 2.27, 95% CI, 0.79 to 3.75, P = 0.003), robot-assisted screw placement technique scores were higher than the traditional freehand technique. Additionally, operative time (SMD = -12.72, 95% CI, -19.74 to -5.70, P = 0.0004), healing time (SMD = -13.63, 95% CI, -20.18 to -7.08, P < 0.0001), frequency of X-ray fluoroscopy (SMD = - 13.64, 95% CI, - 18.32 to - 8.95, P < 0.00001), frequency of guide pin insertion (SMD = - 7.95, 95% CI, - 10.13 to - 5.76, P < 0.00001), and intraoperative blood loss (SMD = - 17.33, 95% CI, - 23.66 to - 11.00, P < 0.00001) were lower for patients who underwent robotic-assisted screw placement than those for patients who underwent the conventional freehand technique.

CONCLUSION

Compared to the freehand nailing technique, robot-assisted nailing helps improve postoperative healing rates in patients with femoral neck fractures; shortens healing times; better restores hip function; reduces the number of intraoperative fluoroscopies, guides pin placements; reduces intraoperative bleeding; and increases perioperative safety.

Single-plane osteotomy model is inaccurate for evaluating the optimal strategy in treating vertical femoral neck fractures: A finite element analysis

BACKGROUND AND OBJECTIVES

The conventional method for simulating vertical femoral neck fractures (vFNFs) is via a vertical single-plane osteotomy (SPO) across the entire femur. However, the accuracy of SPO for evaluating the optimal internal fixation strategy (IFS) and the appropriate assessment parameters is not clear. This study thus aimed to examine the accuracy of SPO in evaluating IFSs and to identify appropriate evaluation parameters using finite element analysis.

METHODS

Eighty patient-specific finite element models were developed based on CT images from eight vFNF patients. The natural fracture model was built using structural features of the affected side, while the SPO was simulated on the healthy side. Five different IFSs were applied to both the natural fracture and SPO groups. Thirteen parameters, including stress, displacement, and stiffness, were subjected to a two-way repeated measures ANOVA to determine the effect of IFSs and fracture morphology on stability. A Pearson correlation analysis was performed on varied parameters with various IFSs to identify independent parameters. Based on these independent parameters, the entropy evaluation method (EEM) score was used to rank the performance of IFSs for each patient.

RESULTS

Eight of the thirteen parameters were significantly influenced by IFSs (p < 0.05), two by fracture morphology (p < 0.01), and none by the interaction between IFS and fracture morphology. In the natural fracture group, parameters including screw stress and displacement, bone cut rate (BCR), and compression effects varied independently with distinct IFSs. In the SPO group, trunk displacement, BCR, cut-out risk, and compression effects parameters changed independently. The BCR of the Alpha strategy was significantly higher than that of the Inverted strategy in the natural fracture group (p = 0.002), whereas the opposite was observed in the SPO group (p = 0.016). Regarding compression effects, two IFS pairings in the natural fracture group and seven IFS pairings in the SPO group exhibited significant differences. None of the five IFSs achieved the optimal EEM score for each patient.

CONCLUSIONS

The single-plane osteotomy model may have limitations in assessing IFSs, particularly when the bone cut rate and compression effects are the main influencing factors. Parameters of the screw stress and displacement, BCR, and compression effects appear to be relevant in evaluating IFSs for natural fracture models. It indicates that individualized natural fracture models could provide more comprehensive insights for determining the optimal IFS in treating vFNFs.

Evaluation of full thread screw and different fixation configurations in Pauwels type III femoral neck fracture

Objectives

The purpose of this study is to evaluate the value of full thread screw and different fixation configurations in Pauwels type III femoral neck fracture.

Methods

A total of 40 artificial femoral model specimens were chosen, and Pauwels type III femoral neck fracture was simulated upon osteotomy at 80°. According to random number table, models were divided into four groups (10 cases in each group): Group A received the paralleled fixation with three partial thread screws (PTSs), group B received the crossed fixation with three PTSs, group C received the paralleled fixation with two full thread screws (FTSs) and one PTS, and group D received the crossed fixation with two FTSs and one PTS. Changes including the model rigidity, axial displacement in fatigue test and limit loads for Pauwels type III femoral neck fracture models were analyzed through MTS 858 Mini Bionix Ⅱ test system.

Results

Among four groups, the model rigidity, axial displacement in fatigue test and limit loads were the highest in group D, and they were the lowest in group A. However, the model rigidity, axial displacement in fatigue test and limit loads between group B and group C showed no statistically significant difference (P＞0.05). Eventually, all the specimens were displaced along the fracture lines while the femoral head was split at varying degrees. After splits, the removal rate of fixation screws in group A (60.0 %) and group C (40.0 %) was significantly higher than that of group B (10.0 %) and group D (0 %) (P＜0.05), but it showed no statistically significant difference between group A and group C, and between group B and group D (P＞0.05).

Conclusions

The crossed fixation configuration with two FTSs and one PTS in group D is proven to be more effective, which can go against the shear stress, tension and introversion in Pauwels type III femoral neck fracture models.

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.

Research hotspots and trends in internal fixation of femoral neck fractures from 2010 to 2022: A 12-year bibliometric analysis

BACKGROUND

This study endeavors to scrutinize the hotspots and trends in the literature concerning the internal fixation of femoral neck fractures (INFNF) through a comprehensive bibliometric analysis. Notably, this analytical process encompasses both qualitative and quantitative components.

METHODS

The present study has utilized the Science Citation Index-Expanded from the Web of Science Core Collection to extract datasets ranging from January 1, 2010, to August 31, 2022. Quantitative analysis was carried out using sophisticated analytical tools such as the Bibliographic Item Co-Occurrence Matrix Builder, the Online Analysis Platform of Literature Metrology, and CiteSpace software. Further, the major Medical Subject Headings terms and their subheading counterparts associated with INFNF were extracted from the PubMed2XL website using the corresponding PMIDs. These Medical Subject Headings terms were employed in conducting a co-word clustering analysis. Ultimately, the Graphical CLUstering TOolkit program was utilized to execute a co-word biclustering analysis to discern the prevailing hotspots in this domain.

RESULTS

Between January 1, 2010, and August 31, 2022, a total of 463 publications were issued on INFNF. The INJURY-INTERNAL JOURNAL OF THE CARE OF THE INJURED stood out as the most extensively perused journal in this area. Notably, China emerged as the foremost contributor to publishing articles within the last 12 years, followed by the United States and Canada. McMaster University was identified as the leading institution in INFNF research, while Bhandari M emerged as the most prolific author in this field. Moreover, the study identified five notable research hotspots within the domain of INFNF.

CONCLUSIONS

This study has identified five critical areas of research in the field of INFNF. It suggests that the primary focus of future research is likely to center on advancing internal fixation methods and robot-assisted instrumentation for femoral neck fractures. As such, this study provides valuable insights into future research directions and ideas for those working in this field.

Biomechanical evaluation of compression buttress screw and medial plate fixation for the treatment of vertical femoral neck fractures

OBJECTIVE

To compare the biomechanical properties of compression buttress screw (CBS) fixation with three plate fixation methods for the treatment of vertical femoral neck fractures (FNFs).

METHODS

A total of forty synthetic femoral models with simulated Pauwels type III fractures (angle of 70°) were equally assigned to one of four fixation groups: CBS fixation, anteromedial plate fixation (AMP), medial buttress plate fixation (MBP) and medial buttress plate fixation without proximal screw (MBPw). Within each group, half of the specimens were randomly assigned to two loading settings, an axial compression loading test and a hip-flexion torsion test.

RESULTS

There were no significant differences in axial load to failure, axial stiffness, torsional strength, or torsional stiffness when comparing CBS with MBP (p>0.05). In the axial compression loading test, both CBS and MBP showed higher load to failure and axial stiffness than MBPw (p<0.05). In torsional testing, AMP exhibited superior torsional strength and torsional stiffness than both MBPw and MBP (all p<0.05) and a higher torsional strength than CBS fixation (p<0.05). There were no significant differences in torsional stiffness between the CBS and AMP fixation groups (p>0.05).

CONCLUSION

The biomechanical parameters of CBS fixation are comparable to that of AMP and MBP, and demonstrate superior axial stiffness than MBPw fixation. Although the CBS method for surgical fixation of vertical FNF holds promise as a less invasive surgical technique than plate fixation with similar biomechanical assessments, further clinical evaluation is warranted.

Reoperation rate and implants’ position variation features of displaced femoral neck fractures with sliding compression or length-stable fixation in young and middle-aged population

Introduction

Sliding compression fixation and length-stable fixation are two basic internal fixation concepts in the treatment of displaced femoral neck fractures. In this study, we aimed to compare the reoperation rates for different methodologies of internal fixation for femoral neck fractures in young and middle-aged population.

Materials and methods

This a retrospective study. A total of 215 patients with displaced femoral neck fractures treated with cannulated screw fixation were enrolled and divided into the sliding compression and length-stable groups according to the fixation pattern. The occurrence of and reason for revision surgery within one year were recorded. Forty-five patients with complete CT data (including CT scanning on the first postoperative day and at the last follow up) were selected from the total sample. A newly established computerized image processing method was used to evaluate variations in the spatial location of screws.

Results

The reoperation rate was significantly higher in the length-stable group (23.8%) than in the sliding compression group (7.3%). The rate of revision surgery due to nonunion was also higher in the length-stable group (11.4%) than in the sliding compression group (1.8%). However, no significant difference was observed in terms of joint penetration or soft tissue irritation. The sliding compression group (6.58 ± 3.18 mm) showed higher femoral neck shortening than length-stable group (4.16 ± 3.65 mm). When analyzing the spatial variations, a significantly greater screw withdrawal distance was observed in the sliding compression group than in the length-stable group, but with a smaller rotation angle.

Conclusion

Length-stable internal fixation of displaced femoral neck fractures may lead to an increased reoperation rate in young and middle-aged population.

Trial registration

Name of the registry: Chinese Clinical Trial Registry.

Trial registration number: ChiCTR2000032327.

Trial registration date: 2020–4-26.

[Research progress in biomechanics of common internal fixation for femoral neck fracture]

OBJECTIVE

To summarize the characteristics and biomechanical research progress of common internal fixation for femoral neck fractures in recent years, so as to provide reference to clinical treatment of femoral neck fracture.

METHODS

The domestic and foreign relevant literature on biomechanics of internal fixation of femoral neck fracture in recent years was reviewed, and the biomechanical research progress was summarized.

RESULTS

Among the internal fixations currently used in the treatment of femoral neck fractures, three cannulated screws can provide sliding compression at the end of the fracture, but the shear resistance is weak, and the risk of long-term internal fixation failure is high; dynamic hip screw and proximal femoral locking plate have excellent angle stability and overall strength; medial buttress plate can transform vertical shear force into compressive stress to promote fracture healing and produce a certain anti-rotation effect; femoral neck system can support the fracture in multi-axial direction, with excellent anti-rotation and anti-shortening properties; and cephalomedullary nails have high overall strength and failure load. Different internal fixations have their own indications due to differences in structure and biomechanics.

CONCLUSION

At present, there is no detailed standard guidance of internal fixation selection. Clinically, the appropriate treatment should be selected according to the fracture types of patients.