Reduced complication rates for unstable trochanteric fractures managed with third-generation nails: Gamma 3 nail versus PFNA

Biomechanical evaluation of a modified intramedullary nail for the treatment of unstable femoral trochanteric fractures

Background

The Proximal Femoral Nail Antirotation (PFNA) device is the most commonly used implant to fix unstable femoral trochanteric fractures (UFTFs), but it has a relatively high incidence of complications. Due to this factor, the modified intramedullary nail (MIN) was created to treat patients with UFTFs. The aim was to exhibit the MIN and make a comparison with PFNA and InterTAN using biomechanical methods.

Methods

An adult UFTF model was developed using Mimics software. The PFNA, InterTAN nail, and MIN models were drawn referring to the corresponding parameters and installed in the fracture models. Vertical, anteroposterior (AP) bending, and torsion loads of the femoral head were set in advance and loaded onto the fracture models. The value of maximal displacement and von Mises stress was evaluated via finite element analysis (FEA).

Results

The MIN model had smaller values for maximal displacement than that of the PFNA model, and the increase in displacement was less pronounced for the MIN compared to PFNA under increasing vertical loads. For the indicator of von Mises stress, the MIN model showed lower stress compared with the PFNA model in vertical loads ranging from 300 N to 2100 N. Except for the maximal stress at implants under AP bending loads, the MIN demonstrated the most superior biomechanical properties under AP bending and torsional loads.

Conclusion

The MIN offered obvious advantages in terms of mechanical stability and stress distribution among the three studied implants, providing a promising implant option for patients with UFTFs.

Intertrochanteric (Reverse Oblique) Fracture Subclassifications AO/OTA 31-A3 Have No Effect on Outcomes or Postoperative Complications

Background

Reverse oblique intertrochanteric fractures (ROFs) are unstable extracapsular hip fractures that present a mechanical challenge. These fractures are classified as AO/Orthopaedic Trauma Association (OTA) 31-A3 according to the Trauma Association classification system and can further be subclassified into 3 subtypes based on their specific characteristics. The study aimed to evaluate and compare the radiographic and clinical outcomes of the 3 subtypes of ROFs.

Methods

A retrospective study was conducted at a single high-volume, tertiary center, where data were collected from electronic medical records of consecutive patients who underwent surgical fixation of AO/OTA 31-A3 fractures. Patients with less than 1-year follow-up, pathological fractures, and revision surgery were excluded. The subtypes of fractures were classified as 31-A3.1 (simple oblique), 31-A3.2 (simple transverse), and 31-A3.3 (wedge or multi-fragmentary). The operation was done using 4 different fixation methods, and radiological evaluation was performed at routine intervals.

Results

The final population consisted of 265 patients (60.8% women) with a mean age of 77.4 years (range, 50-100 years) and the mean follow-up time was 35 months (range, 12-116 months). The incidence of medical complications was similar across the groups. However, there was a trend toward a higher incidence of orthopedic complications and revision rates in the 31-A3.2 group, although this was not statistically significant (p = 0.21 and p = 0.14, respectively).

Conclusions

Based on the findings of this study, no significant differences were observed between the groups, indicating that the subclassifications of AO/OTA 31-A3 fractures do not have a significant impact on surgical outcomes or the occurrence of postoperative complications.

Biomechanical evaluation of a new intramedullary nail compared with proximal femoral nail antirotation and InterTAN for the management of femoral intertrochanteric fractures

Purpose: Surgical treatment is the main treatment method for femoral intertrochanteric fractures (FIFs), however, there are lots of implant-related complications after surgery. Our team designed a new intramedullary nail (NIN) to manage such fractures. The purpose of this study was to introduce this new implant and compare it with proximal femoral nail antirotation (PFNA) and InterTAN for treating FIFs. Methods: An AO/OTA 31-A1.3 FIF model was built and three fixation models were created via finite element method, comprising PFNA, InterTAN, and the NIN. Vertical, anteroposterior (A-P) bending, and torsional loads were simulated and applied to the three fixation models. Displacement and stress distribution were monitored. In order to compare PFNA and the NIN deeply, finite element testing was repeated for five times in vertical load case. Results: The finite element analysis (FEA) data indicated that the NIN possessed the most outstanding mechanical properties among the three fixation models. The NIN model had lower maximal stress at implants compared to PFNA and InterTAN models under three load conditions. The trend of maximal stress at bones was similar to that of maximal stress at implants. Besides, the NIN model showed smaller maximal displacement compared with PFNA and InterTAN models under vertical, A-P bending, and torsional load cases. The trend for maximal displacement of fracture surface (MDFS) was almost identical with that of maximal displacement. In addition, there was significant difference between the PFNA and NIN groups in vertical load case (p < 0.05). Conclusion: Compared with PFNA and InterTAN, the NIN displayed the best mechanical properties for managing FIFs, including the lowest von Mises stress at implants and bones, and the smallest maximal displacement and MDFS under vertical, A-P bending, and torsional load cases. Therefore, this study might provide a new choice for patients with FIFs.

Mortality and functional consequences after revision osteosynthesis for peritrochanteric fractures treated by intramedullary nail: A retrospective study of 312 patients

INTRODUCTION

Osteosynthesis of peritrochanteric fractures by intramedullary nail is associated with a 3 to 15% rate of complications requiring revision surgery. The objective of our study was to compare mortality and autonomy between patients who required revision surgery after osteosynthesis, and patients without revision surgery.

HYPOTHESES

Patients who underwent revision surgery after osteosynthesis of a peritrochanteric fracture by intramedullary nail did not exhibit excess mortality or loss of autonomy compared to those who did not undergo revision surgery.

METHODS

Between January 2017 and October 2019, 312 consecutive patients were operated on for a peritrochanteric fracture by intramedullary nail. Among them, 23 patients (7.4%) required revision surgery (change, nail removal, total hip arthroplasty). Mortality at 90 days and at one year was evaluated and compared between the group of "revision" patients and "no revision" patients. The level of autonomy was assessed by the Parker and Palmer score, one year postoperatively and compared between the 2 groups.

RESULTS

The patients requiring revision surgery were younger: 73 years old vs. 86 years old (p<0.011). The overall mortality was 7.25% at 90 days after surgery and 15% at one year. Mortality was zero at 90 days, and at 1 year, postoperatively for patients requiring revision surgery. There was no significant difference for the mortality at 90 days (p=0.39) between the 2 groups, however at 1 year, it was significantly less for the revision patients (0% vs. 17%, p=0.032). There was no significant difference for the Parker score between the "revision" group; 5 (4-9) and the "no revision" group; 4 (3-7), at one year postoperatively (p=0.24).

CONCLUSION

This study did not show any excess mortality, nor loss of autonomy at 1 year postoperatively, for patients who required osteosynthesis for a trochanteric fracture, and who presented with a complication requiring revision surgery.

LEVEL OF EVIDENCE

III, comparative retrospective study.

Triangular support intramedullary nail: A new internal fixation innovation for treating intertrochanteric fracture and its finite element analysis

BACKGROUND

Proximal femoral nail anti-rotation (PFNA) and Gamma nail were recommended for intertrochanteric fracture, however, with high rate of post-operation complications. The triangular support intramedullary nail (TSIN) was designed to reduce the risk of postoperative complications related to Gamma nail and PFNA, and the aim is to compare the biomechanical characters of Gamma nail, PFNA and TSIN for fixation of intertrochanteric fracture and prove the rationality of the concept of triangle fixation in the treatment of intertrochanteric fractures.

METHODS

The finite element model of proximal femur was constructed according to the CT data of femur. Intertrochanteric fracture models with Evans type Ⅰ and Ⅳ were established and fixed with Gamma nail, PFNA and TSIN by UG-NX 12.0. The finite element analysis software was used to compare the stress distribution and displacement of three implants fixation models.

RESULTS

Under axial loading of 600 N, the peak stress and maximum displacement of intact proximal femur was 13.78 MPa and 1.33 mm, respectively. The maximum stress of TSIN for fixation of Evans type Ⅰ and Ⅳ intertrochanteric fractures was 86.23 MPa and 160.63 MPa which was significantly lower than that of Gamma nail and PFNA. The maximum relative displacement of fracture section in Gamma nail and PFNA fixation models was 0.18 mm and 0.19 mm which has 135% and 148% higher than in TSIN fixation models for fixing Evans type Ⅰ intertrochanteric fracture, and 0.47 mm and 0.59 mm which has 91% and 140% higher than in TSIN fixation models for stabilization of Evans type Ⅳ intertrochanteric fracture.

CONCLUSION

Compared with Gamma nail and PFNA fixation, TSIN has superior advantages in stress distribution and construct stability. We believe that triangle fixation concept help to reduce the risk of post-operative complications associated with PFNA and Gamma nail and improve the clinical effect of intertrochanteric fracture.

From Bad to Disaster: Iatrogenic Fracture Followed by Knee Perforation With Bone Fragments During Femoral Nailing

Intramedullary nailing is the preferred treatment method in tibial, femoral shaft, and sub- or intertrochanteric fractures. Despite good results, a number of complications have been well-characterized. Joint perforation by bone fragment during nail insertion is one such complication.

We report an eventful case of a 63-year-old female patient who presented with an intertrochanteric fracture. Osteosynthesis with a short proximal femoral nail was complicated by a well-known and recognized on-time complication - an iatrogenic fracture of the femoral shaft. However, it was further complicated by knee arthrodesis by a bone fragment when a long nail was inserted. The bone fragment not only “closed” the knee joint, but fractured the medial tibial condyle and protruded into the medial soft tissues of the joint. This misfortune was not recognized intraoperatively and led to revision surgery in the short term and joint post-traumatic arthrosis with resultant total knee replacement in the long term.

Low filling ratio of the distal nail segment to the medullary canal is a risk factor for loss of anteromedial cortical support: a case control study

Background

Anteromedial cortical support apposition (positive and/or neutral cortical relations) is crucial for surgical stability reconstruction in the treatment of trochanteric femur fractures. However, the loss of fracture reduction is frequent in follow-ups after cephalomedullary nail fixation. This paper aimed to investigate the possible predictive risk factors for postoperative loss of anteromedial cortex buttress after nail fixation.

Methods

A retrospective analysis of 122 patients with AO/OTA 31A1 and A2 trochanteric femur fractures treated with cephalomedullary nails between January 2017 and December 2019 was performed. The patients were classified into two groups according to the postoperative status of the anteromedial cortical apposition in 3D CT images: Group 1 with contact “yes” (positive or anatomic) and Group 2 with contact “No” (negative, loss of contact). The fracture reduction quality score, tip-apex distance (TAD), calcar-referenced TAD (Cal-TAD), Parker ratio, neck-shaft angle (NSA), and the filling ratio of the distal nail segment to medullary canal diameter in anteroposterior (AP) and lateral fluoroscopies (taken immediately after the operation) were examined in univariate and multivariate analyses. Mechanical complications were measured and compared in follow-up radiographs.

Results

According to the postoperative 3D CT, 84 individuals (69%) were categorized into Group 1, and 38 individuals (31%) were classified as Group 2. The multivariate logistic regression analysis showed that the poor fracture reduction quality score (P < 0.001) and decreasing filling ratio in the lateral view (P < 0.001) were significant risk factors for the loss of anteromedial cortical contact. The threshold value for the distal nail filling ratio in lateral fluoroscopy predicting fracture reduction re-displacement was found to be 53%, with 89.3% sensitivity and 78.9% specificity. The mechanical complication (varus and over lateral sliding) rate was higher in Group 2.

Conclusions

The fracture reduction quality score and the decreasing filling ratio of the distal nail to the medullary canal in the lateral view (a novel parameter causing pendulum-like movement of the nail) were possible risk factors for postoperative loss of anteromedial cortical support.

Conventional versus helical blade screw insertion following the removal of the femoral head screw: a biomechanical evaluation using trochanteric gamma 3 locking nail versus PFN antirotation

OBJECTIVE

When a hip screw needs to be changed, choosing between the conventional (C-type) and helical blade (H-type) types is difficult. In this biomechanical study, we compared these two screw types relative to the type of the initial screw used.

METHODS

C- or H-type screws were inserted (leading screw) in three types of polyurethane bone models (Sawbone, Pacific Research Laboratories, Inc., Washington, USA: 130 × 180 × 40 mm) of different bone mineral densities (pounds per cubic feet [PCF] 5, 80 kg/m³; PCF 10, 160 kg/m³; and PCF 15, 240 kg/m³), and then successively or alternately inserted (following screw) after the leading screw removal. An original model (original C and H) of a leading screw without removal was created as a control. The strengths of resistance to pullout (PO) and rotational stress were measured. For each experimental condition, there were 30 experimental models.

RESULTS

The original C screw was superior in PO strength, and the original H-type screw was superior in rotational strength. When the C- or H-type screw was the leading screw, using the C-type screw again as the following screw (C1-C2, H1-C2) showed the greatest resistance to PO, and using the H-type screw as the following screw (C1-H2, H1-H2) showed superior resistance to rotational strength. However, the rotational strength of the C2 screw decreased by more than 50% compared with that of the original C screw. Moreover, the PO and rotational strengths of the H2 screw decreased to less than 30% overall compared with those of the original H screw.

CONCLUSION

The H-type screw should be used for second-time screw insertion procedures in cases where it is difficult to choose between PO and rotational strengths.