Parallel and non-parallel cannulated screw fixation complications in femoral neck fractures: A systematic review and meta-analysis

Screw Configuration Does Not Significantly Alter Neck Shortening After Valgus-Impacted Femoral Neck Fracture (OTA Type 31B1.1)

OBJECTIVES

To compare 3 different cancellous screw configurations used for Garden 1 femoral neck fractures (FNFs).

METHODS

DESIGN

Retrospective review.

SETTING

A large urban academic medical center.

PATIENT SELECTION CRITERIA

All patients with Orthopaedic Trauma Association 31B1.1 FNF who underwent in situ fixation with cancellous screws between 2012 and 2021 were included. Patients were divided into 3 groups: 2 screws placed in a parallel fashion, 3 screws placed in an inverted triangle configuration, and 3-screw fixation with placement of 1 "out-of-plane" screw perpendicular to the long axis of the femur.

OUTCOME MEASURES AND COMPARISONS

Postoperative femoral neck shortening (mm) was the primary outcome, which was compared among the 3 groups of different screw configurations.

RESULTS

Sixty-one patients with a median follow-up of 1 year (interquartile range 0.6-1.8 years) and an average age of 72 years (interquartile range 65.0-83.0 years) were included. All fractures demonstrated bony healing. Overall, 68.9% of the cohort had ≤2 mm of femoral neck shortening. There was no difference between groups in the proportion of patients who experienced greater than 2 mm of shortening (P = 0.839) or in the amount (mm) of femoral neck shortening (Kruskal-Wallis χ2 = 0.517, P = 0.772).

CONCLUSIONS

Although most patients with valgus-impacted FNF treated with screw fixation do not experience further femoral neck shortening, some patients demonstrated continued radiographic shortening during the healing process. The development of further femoral neck shortening and the amount of shortening that occurs do not differ based on implant configuration. Multiple different screw configurations seem to be acceptable for achieving healing and minimizing further femoral neck impaction.

LEVEL OF EVIDENCE

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

Analysis of risk factors for modification of femoral offset after internal fixation of Garden I and II femoral neck fractures

BACKGROUND

The concept of restoring the femoral offset is well established during hip replacement surgery, but is less well known when treating Garden I or II femoral neck fractures by internal fixation. And yet, the therapeutic aim for these fractures is to restore this native parameter as best possible. The aim of this study was to identify the risk factors for reduction of femoral offset after union of a Garden I or II femoral neck fracture treated by internal fixation.

HYPOTHESIS

After internal fixation of a femoral neck fracture, certain factors may contribute to reducing the femoral offset, which itself has been identified as being responsible for altering the patients' quality of life and functional outcomes.

MATERIALS AND METHODS

This multicenter study included 193 patients who had a Garden I or II femoral neck fracture treated by cannulated screws or a sliding compression screw-plate. The difference between the femoral offset in the operated hip and that of the contralateral hip was measured in weightbearing patients after the fracture had healed. This difference was the primary outcome measure. Univariate and multivariate analyses were done to look for risk factors contributing to femoral neck shortening.

RESULTS

Based on the univariate analysis, being more than 85 years of age, having a Garden I fracture, and cannulated screw fixation were associated with a significantly greater reduction in the femoral offset. In the multivariate analysis, only Garden I fractures were associated with a greater reduction in femoral offset.

DISCUSSION

Garden I fractures were associated with a greater reduction in the offset, although there was no evidence that this change was related to early weightbearing. By identifying this risk factor, surgeons can optimize the indications given that the treatment of these fractures is still widely debated and there is still no consensus as to the best method.

LEVEL OF EVIDENCE

IV.

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

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

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.

Mechanical study of the application of compression screw nails in the cross-inverted triangular pattern for internal fixation of femoral neck fractures

OBJECTIVE

To design a cross-inverted triangular pattern to insert compression screw nails for the treatment of femoral neck fractures and to compare the biomechanics of inserting compression screw nails in cross-inverted triangular patterns and inverted triangular patterns. I am very sorry that a corresponding author needs to be added to the article. I do not know how to insert it, so I make a note here. Please check the attachment I uploaded.

METHODS

The reasonableness of the model is first analyzed using finite elements. A total of 6 adult human specimens were selected, of which 3 males and 3 females were divided into the A1, B1, and C1 groups and the A2, B2, and C2 groups by the random number table method. The A1 and A2 groups were made into subhead femoral neck fracture models, the B1 and B2 groups were made into trans-neck femoral neck fracture models, and the C1 and C2 groups were made into basal femoral neck fracture models. The right femur of each group had a compression screw nail inserted in the crossed-inverted triangular pattern, and the left femur of each group had a compression screw nail inserted in the inverted triangular pattern. The static compression test was performed by an electronic universal testing machine. The maximum load of the femoral neck and the load of 3.00 mm axial displacement of the femoral head were read according to the pressure-displacement curve drawn in the experiment.

RESULTS

The finite element analysis showed that the cross-inverted triangular hollow threaded nail has better conductivity and more stable fixation than the inverted triangular hollow threaded nail. The maximum load of the femoral neck and the load of 3.00 mm axial displacement of the femoral head of the left femur were greater than those of the right femur in the A1, A2, B1, B2 and C2 groups, while the maximum load of the femoral neck and the load of 3.00 mm axial displacement of the femoral head of the left femur were smaller than those of the right femur in the C1 group. There was no statistically significant difference in the maximum load of the femoral neck or the load of 3.00 mm axial displacement of the femoral head between the A1 and A2 groups, the B1 and B2 groups, or the C1 and C2 groups (P > 0.05). After the K-S test, the maximum load of the femoral neck and the load of 3.00 mm axial displacement of the femoral head were normally distributed (P = 0.20), and the LSD-t test was conducted for the two load data; the difference was not statistically significant (P = 0.235).

CONCLUSION

The effect of compression screw nails in the cross-inverted triangular pattern was the same in males and females, and stability was better in the fixation of subhead and trans-neck femoral neck fractures. However, its stability in fixation of basal femoral neck fracture is worse than that of the inverted triangular pattern. The cross-inverted triangular hollow threaded nail has better conductivity and more stable fixation than the inverted triangular hollow threaded nail.

Do the Number, Size, and Position of Partially Threaded Screws Affect the Radiological Healing of Surgically Treated Displaced Femoral Neck Fractures? A Review of 136 Children

Background and Objectives: The quantity, size, and position of implants might affect the fracture healing process of surgically treated displaced pediatric femoral neck fractures (PFNFs). The aim of this retrospective multicenter study was to evaluate the correlation between the time needed to achieve radiological union and the number, size, and location of the partially threaded cannulated screws (PTCSs) in children with displaced PFNFs. Materials and Methods: A retrospective review of 136 children (mean age: 10.6 ± 3.8 years) with displaced PFNFs treated by two (n = 103) or three (n = 33) PTCSs was carried out. Student’s t-tests, one-way ANOVA, Cox regression analysis, and multiple linear regression analyses were performed to investigate the variables affecting the time needed to achieve radiological fracture healing according to the number, size, and position of PTCSs, as assessed on plain radiographs. Results: A total of 132 hips achieved union at an average of 3.2 ± 1.6 months after the initial surgery. The time needed to achieve union in the patients treated with two or three PTCSs was comparable (p = 0.36). Among the fractures treated by two PTCSs, the time needed to achieve union did not correlate with the size of the implant (p = 0.122), or with the angulation between the PTCSs on anterior–posterior (p = 0.257) and lateral radiographs (p = 0.547). The time needed to achieve union in the fractures that were fully compressed by the implants was similar to the partially compressed fractures (p = 0.08). Conclusions: The number, size, and position of the PTCSs do not affect the radiological healing in the children with displaced PFNFs treated surgically.