Cement augmentation of the proximal femoral nail antirotation for the treatment of two intertrochanteric fractures - a comparative finite element study

Background There are concerns regarding initial stability and cutout effect in proximal femoral nail antirotation (PFNA) treating intertrochanteric fractures. No study have used finite element analysis (FEA) to investigate the biomechanics. This study aimed to compare the cutout effect, stress and displacement between stable (AO31-A1.3) and unstable (AO31-A2.2) intertrochanteric fractures treated by cement augmented PFNA. Methods Four femoral finite element models (FEMs) were constructed and tested under the maximum loading during walking. Non-augmented and augmented PFNA in two different intertrochanteric fractures were respectively simulated, assuming Tip Apex Distance (TAD) < 25 mm within each FEM. The cutout effect, stress and displacement between femur and PFNA were compared in each condition. Results Cutout effect was observed in both non-augmented femoral head and was more apparently in unstable intertrochanteric fracture model. After reinforced by bone cement, no cutout effect occurred in two models. Stress concentration were observed on medial part of intertrochanteric region and the proximal part of helical blade before augmented while were observed on femoral shaft and the conjunction between blade and nail after augmented in both FEMs. Displacement mainly appeared on femoral head and the helical blade tip before augmented while distributed moderately on intertrochanteric region and the upper part of nail after augmented in both FEMs. The maximum stress and displacement value of femur decreased both in stable and unstable model after augmented but was more significantly in the unstable one. The maximum stress and displacement value of PFNA increased both in stable and unstable model after augmented but was more significantly in the unstable one. Conclusion Our FEA study indicated that the cement augmentation of the PFNA biomechanically enhances the cutout resistance in intertrochanteric fracture, this procedure is especially efficient for the unstable intertrochanteric fracture.

INTERTROCHANTERIC FRACTURES FIXATION WITH PFN AND PFNA2 PROXIMAL FEMORAL NAILS- PROSPECTIVE RANDOMISED COMPARATIVE STUDY ASSESSING FUNCTIONAL OUTCOME

Introduction: Trochanteric fractures are among the most common injuries which are usually resulting from minimal to moderate physical trauma to areas of bone signicantly weakened by osteoporosis. The greatest problems for the orthopaedic surgeon to treating the unstable trochanteric fracture and the complications (implant failure, varus collapse, non-union) occur from xation that result of instability. The implants have evolved from extramedullary implants like dynamic hip screw to the intramedullary types of PFNA2 nail. 50 patients were included in our study from July 2019 to July 2021. 25 patient Material And Methods : s were treated with PFNA2 (Group I) and 25 patients with PFN (Group II) Nails. Mean blood loss during surgery was 153.8±10.92 Results : & 201.6±38.48 in group I & group II respectively and the mean duration of surgery in group I and group II was 65.24+6.57 min and 85.44 + 11.08 min respectively. Conclusion : We concluded that use of helical blade PFN is certainly better in 31A2.2 and 31A3.3 type of fracture than screw PFN.

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.

Bent or broken: analysis of set screw fracture in the TFNa implant

Objectives To evaluate set screw fracture in the Trochanteric Femoral Nail Advanced implant (TFNa, Synthes, West Chester, PA) and to identify additional mechanisms of set screw failure in the TFNa. Materials and methods Patients who had experienced failure after open reduction and internal fixation (ORIF) with the TFNa were identified. TFNa implants were explanted and inspected following revision surgery. Medical device reports (MDRs) and manufacturer’s inspection reports describing similar failures for the TFNa in the United States Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database were also reviewed. Results Four set screw fractures that occurred at a level II trauma center were observed. Sixty-seven reported failures were identified in the MAUDE database for review. Twenty-eight failed implants were returned to the manufacturer for inspection with a published inspection report available for analysis. Set screw fractures can occur in the TFNa when the set screw is deployed prematurely into the proximal screw aperture prior to blade/screw insertion. The set screw can also bend and deform if it is advanced against a helical blade/lag screw that is not fully seated into position, thereby potentially compromising its function. Conclusion The TFNa set screw allows for potential fracture during implant insertion leading to uncontrolled collapse, early excessive proximal femoral shortening, and rotational instability of the helical blade/lag screw. Similar failures in the TFNa can be prevented by having the surgeon inspect the proximal screw aperture after attachment of the proximal aiming aim to ensure the set screw has not been deployed prematurely. Level of evidence Therapeutic Level III.

RESULTS OF TFN AND SHORT PFNA-II IN UNSTABLE TROCHANTERIC FRACTURES: A RETROSPECTIVE COMPARATIVE STUDY

Background: Advancements in modern medicine have given people the opportunity to live longer. The resultant increase in the elderly population has led to a higher incidence of peri-trochanteric fractures of the femur. The preferred implant for the comminuted unstable variety has been intramedullary nails with one or two head/neck compression screws, which are known to have high rate of complications like screw cut-out, back out, Z-effect, varus collapse and rotational instability, especially in the osteoporotic patients leading to the development of helical blade systems. Here we have compared the results of trochanteric xation nail (TFN) and short proximal femoral nail antirotation (PFNA)-II. Methods: It was a retrospective, comparative study in seventy-ve patients with comminuted unstable trochanteric fractures (AO classication31A2) treated using TFN in 34 and short PFNA-II in 41 patients with a minimum follow up period of six months. Results: Most of the data were comparable between the two groups except: signicantly higher operation time and implant-related complications in the TFN group. No signicant differences in the functional outcome between the two groups were noted as indicated by Harris Hip Score at six months. Conclusion: Short PFNA-II should be used in preference to TFN for comminuted unstable trochanteric fractures with no sub-trochanteric extension in the elderly osteoporotic patients in view of the shorter operative time, easier insertion and lower complications rate.

PROSPECTIVE RANDOMISED COMPARATIVE STUDY OF PFN AND PFNA2 PROXIMAL FEMORAL NAILS FOR THE TREATMENT OF INTERTROCHANTERIC FRACTURES

Introduction: Trochanteric fractures are among the most common injuries which are usually resulting from minimal to moderate physical trauma to areas of bone signicantly weakened by osteoporosis. The greatest problems for the orthopedic surgeon to treating the unstable trochanteric fracture and the complications (implant failure, varus collapse, non union) occur from xation that result of instability. The implants have evolved from extramedullary implants like dynamic hip screw to the intramedullary types of PFNA2 nail. 50 patients were Material and Methods : included in our study from December 2018 to December 2020. 25 patients were treated with PFNA2 (Group I) and 25 patients with PFN (Group II) Nails. Mean blood loss during surgery was 153.8±10.92 & 201.6±38.48 in group I & group II respectiv Results : ely and the mean duration of surgery in group I and group II was 65.24+6.57 min and 85.44 + 11.08 min respectively. We concluded Conclusion : that use of helical blade PFN is certainly better in 31A2.2 and 31A3.3 type of fracture than screw PFN.