Comparison of the Effect of Rhombic and Inverted Triangle Configurations of Cannulated Screws on Internal Fixation of Nondisplaced Femoral Neck Fractures in Elderly Patients

Biomechanical analysis of fixation strength at different nailing angles for femoral neck fracture with insufficient reduction

To analyze the fixation strength of cannulated screws fixation in the treatment of femoral neck fracture with posterior tilt due to insufficient reduction. Two sets of digital models of anatomical reduction and 15° tilting reduction were established by CT data. Each group of models was modeled with two different fixation methods. One fixation method was fixed according to the standard cannulated screws recommended by AO. Another fixation method is to tilt the screw posterior tilt 15°. The final four groups of models were obtained: AO principle nailing posterior tilt model (Group A), posterior direction nailing posterior tilt model (Group B), AO principle nailing anatomic reduction model (Group C) and posterior direction nailing anatomic reduction model (Group D). The maximum displacement of the fracture end, the maximum Von-Mises stress and the stress distribution of the internal fixation were compared among the four groups. Four groups of models were established on artificial bone by 3D printing guide plate technology. The 600 N pressure test and yield test were performed on a biomechanical machine. The finite element and biomechanical models showed that groups B and C were more stable than groups A and D. The stability of group B was not worse than that of group C. When the femoral neck fracture produces a posterior tilt, a posterior reduction is allowed. The change of AO screw to posterior tilting screw fixation has more powerful advantages. No posterior tilt or posterior reduction, AO screw placement is still required.

Biomechanical difference analysis of new and classic intramedullary nail devices in the treatment of basal femoral neck fractures: finite element analysis

OBJECTIVE

There is currently a lack of in-depth comparative evaluation regarding the biomechanical properties of novel intramedullary nail devices in the treatment of basal femoral neck fractures (BFNF). This study aims to utilize finite element analysis to compare the performance differences of two novel devices with traditional PFNA and InterTan nails in the fixation of BFNF.

METHODS

Based on a validated finite element model, this study constructed an accurate BFNF model and implanted four different intramedullary nail devices: PFNA, InterTan nail, PFBN (proximal femoral biomimetic nail), and NIS (novel intramedullary system). Under a vertical load of 2100N, the displacement and Von Mises stress (VMS) distribution of each group of models were evaluated through simulation testing.

RESULTS

Under a load of 2100N, the PFBN device exhibited the best performance in terms of displacement and peak stress, while PFNA performed poorly. The peak displacement of the NIS device was lower than that of PFNA and InterTan nails, while the peak stress of the InterTan nail was lower than that of PFNA and NIS.

CONCLUSION

The PFBN device demonstrates stronger load-bearing and shear-resistant properties in the treatment of BFNF, and the NIS device also shows significant improvement in stability. Therefore, both the PFBN and NIS devices are reliable internal fixation techniques for the treatment of CFIFs, with potential clinical application prospects.

Femoral neck fracture fixation in rhombic versus inverted triangle configuration in young adults: A systematic review

OBJECTIVE

This review evaluated the outcomes of rhombic versus inverted triangle configuration fixation of femoral neck fractures.

METHODS

Six databases, PubMed, Embase, Scopus, Web of Science, Cochrane Library databases, and China National Knowledge Infrastructure (CNKI), were comprehensibly searched for the comparative studies of two configurations (rhombic versus inverted triangle) of neck femur fracture fixation. Ultimately seven studies were included in this systematic review for qualitative and quantitative analysis. A meta-analysis was performed with the software RevMan 5.4.1.

RESULTS

Fewer nonunion (OR 0.46 with 95 % CI 0.23, 0.94; p = 0.03), and early full weight bearing (MD -3.09 with 95 % CI -5.41, -0.77; p = 0.009) were seen in the rhombic than in the inverted configuration; however, a better hip function (MD 3.72 with 95 % CI 0.99, 6.44; p = 0.008), and lesser less blood loss (MD 3.84 with 95 % CI 1.19, 6.49; p = 0.004) during surgery were found in the inverted triangle configuration. There was no difference between the two fixation configurations regarding the duration of surgery, fracture union time, overall complications, femoral neck shortening, length of hospital stay, fluoroscopy times, and incision size.

CONCLUSION

The rhomboid configuration showed fewer non-union, early weight bearing, better hip function and comparable complications rate than the inverted triangle configuration; however, there was more blood loss intraoperatively than inverted triangle configuration. Hence, the addition of a fourth screw in the rhombic configuration have an added advantage over the inverted triangle configuration in femoral neck fracture.

Finite element analysis of proximal femur bionic nail for treating intertrochanteric fractures in osteoporotic bone

This study compared the biomechanical characteristics of proximal femur bionic nail (PFBN) and proximal femoral nail antirotation (PFNA) in treating osteoporotic femoral intertrochanteric fractures using finite element analysis. Under similar bone density, the PFBN outperforms the PFNA in maximum femoral displacement, internal fixation displacement, stress distribution in the femoral head and internal fixation components, and femoral neck varus angle. As the bone density decreases, the PFBN's biomechanical advantages over PFNA become more pronounced. This finding suggests that the PFBN is superior for treating osteoporotic intertrochanteric femoral fractures.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Finite element analysis of basicervical femoral neck fracture treated with proximal femoral bionic nail

BACKGROUND

Dynamic hip screws (DHS) and proximal femoral nail anti-rotation (PFNA) were recommended for basicervical femoral neck fracture (BFNF), however, with high rate of postoperative femoral neck shortening. The proximal femoral bionic nail (PFBN) was designed to decrease the postoperative complications associated with DHS and PFNA. The aim of this study is to compare the biomechanical characters of DHS, PFNA, and PFBN for fixation of BFNF.

METHODS

Using finite element analysis, we created a three-dimensional model of the BFNF for this investigation. The PFBN group, the PFNA group and the DHS + DS group were our three test groups. For each fracture group, the von Mises stress and displacements of the femur and internal fixation components were measured under 2100 N axial loads.

RESULTS

The PFBN group demonstrated the lowest stress on the implants, significantly lower than the PFNA and DHS + DS groups. In terms of stress on the implants, the PFBN group exhibited the best performance, with the lowest stress concentration at 112.0 MPa, followed by the PFNA group at 124.8 MPa and the DHS + DS group at 149.8 MPa. The PFBA group demonstrated the smallest displacement at the fracture interface, measuring 0.21 mm, coupled with a fracture interface pressure of 17.41 MPa, signifying excellent stability.

CONCLUSIONS

Compared with DHS and PFNA, PFBN has advantages in stress distribution and biological stability. We believe the concept of triangle fixation will be helpful to reduce femoral neck shortening associated with DHS and PFNA and thus improve the prognosis of BFNF.

Comparison of percutaneous compression plate to parallel screws in the treatment of nondisplaced femoral neck fractures in elderly patients: a prospective, randomized study

BACKGROUND

The optimal internal fixation for non-displaced femoral neck fractures remains controversial. This study aimed to compare the clinical results of the percutaneous compression plate (PCCP) with parallel screws (PS) in treating femoral neck fractures in elderly patients.

MATERIALS AND METHODS

A total of 218 patients who underwent internal fixation were randomized to receive either a percutaneous compression plate (PCCP group) or parallel screws (PS group) using a computerized random sequence generator which was used to assign the order of randomization. Patients were assessed by the operating time, intraoperative blood loss, hemoglobin level drop, postoperative hospital stay, the time to full weight-bearing, reduction quality, fracture healing time, Harris hip score, and postoperative complications.

RESULTS

There was no significant difference between PCCP and PS groups regarding operative time, intraoperative blood loss, hemoglobin level drop, postoperative hospital stays, reduction quality, and Harris hip score (p > 0.05). The time to full weight-bearing and the fracture healing time in the PCCP group were shorter than those in the PS group (p < 0.05). The overall complication rates were slightly lower in the PCCP compared to the PS patients, but there was no significant difference (p > 0.05). However, the implant failure rate was significantly higher in the PS group compared to the PCCP group (p < 0.05).

CONCLUSIONS

The present study suggests that the PCCP is superior to the parallel screws fixation in the treatment of non-displaced elderly femoral neck fractures in terms of earlier full weight-bearing, shorter fracture healing time, and lower implant failure rate. Therefore, it may be a better therapeutic strategy for non-displaced femoral neck fractures in elderly patients.

Complications and Outcomes of the Internal Fixation of Non-displaced Femoral Neck Fracture in Old Patients: A Two-Year Follow-Up

Background Fractures of the proximal femur are amongst the most common injuries in the elderly population. While there is a clear consensus regarding the management of displaced femoral neck fractures, the management of non-displaced fractures is less clear. Both fixation and arthroplasty are valid treatment options. Internal fixation is a less invasive procedure, but it carries the risks of non-union and avascular necrosis (AVN) of the femoral head. The literature describes varying complication rates associated with these risks. We aim to describe a series of elderly patients above the age of 65 years with non-displaced fractures of the femoral neck who were treated with internal fixation. Our objectives are to determine the union rate and complications in this group and to elucidate the factors that influence these outcomes. Methods We conducted a retrospective review of all patients aged 65 years and older who presented with femoral neck fractures at our level 1 trauma unit between 2018 and 2020. Fractures were classified using the Garden classification system, and only those with Garden 1 or 2 fractures (non-displaced) were included. Preoperative radiographs or intraoperative fluoroscopy images were used to classify fractures using the Pauwels classification. Serial postoperative radiographs and clinical notes (up to 24 months postoperatively) were reviewed to assess the union rate and the development of complications. Both non-union and AVN were analysed for their associations with age, sex, Pauwels grade and comorbidities. A subgroup analysis of the complications was performed to elucidate their association with age groups (<80 and >80 years) and types of fixations (dynamic hip screws {DHS} and cannulated screws). Results A total of 148 patients, consisting of 60 males and 88 females, were included in the analysis. The patients had a mean age of 78.5 years (ranging from 65 to 98 years). The union rate without any degree of AVN was 90.7%, with six non-unions (4.05%) and six patients experiencing AVN (4.05%). No difference in outcome was detected between the two groups based on age. High (type 2 or 3) Pauwels grade (p = 0.05) and treatment with cannulated screws (p = 0.02) were indicated as significant factors for non-union. All patients who developed AVN were noted to have a comorbidity that is known to predispose them to AVN. Conclusion Our series shows a union rate of 90.7%, which is comparable to the union rates reported in other published literature. Our results suggest that age does not independently influence the outcome of fixation for these fractures. We conclude that fractures with vertical orientation (Pauwels grade 2 or 3), when treated with cannulated screws, are more likely to result in non-union. AVN is the second most common complication after non-union, which is also associated with other risk factors for AVN.

Surgical Tool Handle Vibration-Based Drilling State Recognition During Hip Fracture Fixation

Objectives

Traditional manual drilling during hip fracture fixation can easily lead to unstable fixation and vascular damage. This study aimed to investigate a safe and easy‐to‐use robot‐assisted method to automatically drill bone and distinguish critical bone drilling states with high accuracy in real‐time for the bone hole‐making process during hip fracture fixation.

Methods

A bone‐drilling robotic system was designed to automatically create holes in the femoral neck. Four fresh pig femurs were drilled at the posterosuperior femoral neck using three modes: “all‐in” (AI), “in‐out‐in” (IOI), and “percutaneous fixation” (PF). A high‐frequency accelerometer captured the generated vibrations of the drill handle, which were then transferred to a personal computer using a data acquisition card. Five bone drilling states are defined, including: “drill idling,” “initial drilling,” “in the cancellous bone,” “out the femoral neck,” and “in the cortical bone.” The harmonic distribution of the vibration signal was extracted by fast Fourier transform (FFT) and used as a critical feature to identify different drilling states. To prove the difference in the harmonic distribution at different drilling states, an independent sample t‐test was used to compare the percentage of the first harmonic amplitude in the first 10 harmonics at each drilling state. A neural network classifier was trained with the frequency spectrum as the input and the drilled state as the output to distinguish the critical bone drilling states with high accuracy in real‐time. The classifier was trained and tested on four specimens to ensure that the surgical robot could accurately identify the five drilling states.

Results

In each specimen, the harmonic distributions of the drilling vibration at different drilling modes were significantly different (p < 0.05). The average recognition accuracies of the drilling state for the four specimens were all higher than 84%. The three defined modes were distinguished with extremely high accuracies. The recognition accuracies of “in the cancellous bone” for specimens 1 to 4 were 83.2%, 84.8%, 92.9%, and 84.7%. The recognition accuracies of “in out the femoral neck” from specimens 1 to 4 are 98.2%, 88.4%, 95.8%, and 88.8%. The recognition accuracies of “in the cortical bone” for specimens 1 to 4 were 94.6%, 80.8%, 95.5%, and 85.8%.

Conclusions

The proposed robot‐assisted method can automatically distinguish five critical bone‐drilling states with high accuracy in real‐time to avoid weak fixation and damage to the lateral epiphyseal artery.