Expandable proximal femoral nail versus gamma proximal femoral nail for the treatment of AO/OTA 31A1-3 fractures

Lateral cortical notching facilitates dynamization of proximal femoral nailing - A finite element analysis

INTRODUCTION

Dynamization of proximal femoral nailing by removal of distal interlocking is one of the recommended treatment options for nonunions of femur fractures. However, in certain inter-/subtrochanteric fractures, gliding of the nail along the femoral shaft is blocked by lateral femoral cortical support of the lag screw. For these cases, Biber et al. proposed lateral cortical notching (LCN), in which the supporting lateral bone is removed. This study investigates the biomechanical effect of LCN on gliding of proximal femoral nailing and stress distribution at the bone/implant interface.

MATERIALS AND METHODS

In this finite element analysis a three-dimensional model of an unstable intertrochanteric fracture with proximal femoral nailing without distal interlocking was simulated using the FebioStudio software suite. To simulate LCN, the lag screw hole was lengthened to 15.34 mm at the lateral cortex. Displacement of the nail along the femoral shaft axis and von Mises stress distribution were compared between LCN model and standard implantation model.

RESULTS

Displacement of the nail along the femoral shaft axis was higher in the LCN model than in the standard implantation model (0.48 mm vs. 0.07 mm). Highest von Mises stresses of 176-178 MPa at the implant and of 52-81 MPa at the proximal femur were detected. Maximum von Mises stresses of the implant were comparable at all sides, except for a reduced von Mises stress at the lateral inferior side in the LCN model (80 vs. 102 MPa). At the inferior lateral screw hole and the anterior/posterior lateral screw hole maximum von Mises stress was reduced in the LCN model (2 vs. 49 MPa and 52 vs. 81 MPa), whereas the maximum von Mises stress at the inferior medial screw hole was higher in the LCN model than in the standard implantation model (53 vs. 27 MPa).

CONCLUSIONS

Lateral cortical notching facilitates gliding of a distally dynamized proximal femoral nail along the femoral shaft axis in intertrochanteric fractures. Additionally, the lack of lateral cortical bone support at the lag screw reduces von Mises stress at the bone/implant interface and thus could lower the risk for implant breakage and peri‑implant fractures.

Reduced cutout for reverse oblique intertrochanteric hip fractures treated with trochanteric fixation advanced (TFN-A) nail compared to the short gamma-3 nail

BACKGROUND

Reverse oblique fractures (AO/OTA 31-A3) account for 5-23% of all intertrochanteric fractures and are challenging to manage. The Gamma 3-Proximal Femoral Nail (GPFN) and the Trochanteric Fixation Nail Advanced (TFNA) are two common cephalomedullary systems used to treat this fracture. No study has reported on outcomes with the TFN-A for reverse oblique fractures. This study aimed to compare outcomes and complication rates in patients with reverse oblique fractures, treated with either TFNA or GPFN.

PATIENTS AND METHODS

A total of 203 patients with reverse oblique fractures (137 in the GPFN group and 66 in the TFNA group), were treated in our institution between June 2010 and May 2019. Data was collected on postoperative radiological variables including screw or blade location, and tip-apex distance (TAD). Data were also collected for non-orthopaedic complication rates and orthopaedic complications. A sub-group analysis was additionally performed for different nail lengths.

RESULTS

We found no significant difference in the overall rate of complications and revisions between the two groups. Patients treated with the 235 mm TFN-A nail sustained lower rates of cutout, compared to 180 mm GPFN (GPFN: 6% TFN-A: 0%, p = 0.043). The frequency of revision surgeries and malunions/non-unions did not differ significantly between the two groups and additionally showed no difference in the subgroup analysis.

CONCLUSION

The 235 mm TFN-A was associated with lower rates of cut-out compared to the short GPFN for reverse oblique intertrochanteric fractures. Future well-designed prospective studies are warranted to investigate the role of the TFN-A in improving outcomes for such fractures.

Expandable Proximal Femoral Nail versus Gamma Proximal Femoral Nail for the treatment of hip reverse oblique fractures

BACKGROUND

Reverse oblique intertrochanteric fractures are classified by the AO/OTA as 31A3 and account for 2-23% of all trochanteric fractures. The Gamma 3-Proximal Femoral Nail (GPFN) and the Expendable Proximal Femoral Nail (EPFN) are among the various devises used to treat this fracture. The aim of this study was to compare outcomes and complication rates in patients with AO/OTA 31A1-3 fractures, treated by either a GPFN or an EPFN.

PATIENTS AND METHODS

A total of 67 patients (40 in the GPFN group and 27 in the EPFN group, average age 78.8 years) were treated in our institution between July 2008 and February 2016. Data on postoperative radiological variables, including peg location and tip-apex distance (TAD), as well as orthopedic complications, such as union rate, surgical wound infection and cut-outs rates were also recorded, along with the incidence of non-orthopedic complications and more surgical data. Functional results were evaluated and quantified using the Modified Harris Hip Score (MHHS) and by the Short Form 12 Mental Health Composite questionnaire (SF-12 MHC) in order to assess the quality of life.

RESULTS

The total prevalence of postoperative orthopedic complications including postoperative infection showed a significant difference with a p-value of 0.016 in favor of the EPFN group. Nonetheless, the frequency of revision did not differ between the two groups, being 0.134. The main orthopedic complication in both groups was head cut-out of the GPFN lag screw and the EPFN expendable peg, which was 20% and 7.4%, respectively, and required a revision surgery using a long nail or total hip replacement (THR). However, the average TAD did not significantly differ between groups which might be due to a relatively low cohort to reach a significant difference. Nonunion rate of 5% occurred solely in the GPFN group, with similar results of intraoperative open reduction between both groups. The EPFN group achieved better scores in both questionnaires (p = 0.027 and p = 0.046, respectively). Both the MHHS and SF-12 MCS values significantly differed between groups, with the EPFN group achieving better scores than the GPFN group in both questionnaires (p = 0.027 and p < 0.05, respectively).

CONCLUSIONS

According to this study, the EPFN yields better results in comparison with the GPFN, with relatively less complications rate, for the treatment of unstable reverse oblique pertrochanteric fracture. In light of this results, we conclude that the EPFN might be as good as GPFN for the treatment of reverse oblique intertrochanteric fractures.

LEVEL OF EVIDENCE

Level III retrospective study. The local institutional review board of the Tel Aviv Medical Center approved this study and all the surgeries were done exclusively in this institution.

Nailing unstable pertrochanteric fractures: does size matters?

INTRODUCTION AND OBJECTIVES

New generation cephalomedullary nails are, currently, widely used for the treatment of trochanteric proximal femoral fractures. This study aims to compare the midterm outcomes and complication rates in patients with unstable 31A2 fractures treated with two different lengths of nails.

MATERIALS AND METHODS

Retrospective study including 123 pertrochanteric proximal femoral fractures 31A2 treated with Gamma3 nail^® between January/2017 and January/2019. 19 patients were excluded, resulting in a total of 104 patients with a minimum follow-up of 1 year. Two groups, Long Dynamic Gamma3 Nail (LGN) and Short Static Gamma3 Nail (SGN), with 52 patients each were compared. Mean age was 81 years (range 50-99), being 78% female. Preoperative variables included: age, medical comorbidities, mobility, anesthetic risk, associated fractures, hemoglobin and hematocrit values. Postoperatively, functional and radiological results, quality of life, hemoglobin and hematocrit concentration, transfusion requirements, mobility, and pain were evaluated. Additionally, perioperative complications were also analyzed, such as malunion, non-union, infection rates, cut-outs, and peri-implant fractures.

RESULTS

A correct radiological fracture reduction was obtained in 73% of the cases (73% SGN/74% LGN). Two patients in LGN group had intraoperative complications (greater trochanter fractures). 38% of the patients with LGN presented nail tip impaction upon the distal anterior femoral cortex, associated with anterior knee pain. Blood loss and operative time was statistically different between groups. Despite the previous, no differences in clinical outcomes and quality of life were found.

CONCLUSIONS

The present study comparing two lengths of the Gamma3 Nail in 31A2 fractures showed no overall differences in clinical and radiological outcomes, and complication rates. However, the use of LGN was associated with a statistically significant higher blood loss and operative time, and a tendency for increased need for transfusion, and anterior knee pain and reoperation rate. Therefore, we recommend the use of locked SGN in the treatment of 31A2 fractures.