Periprosthetic fracture fixation in Vancouver B1 femoral shaft fractures: A biomechanical study comparing two plate systems

Abstract

Introduction Periprosthetic fractures of the femur are an increasing problem in today's trauma and orthopaedic surgery. Owing to the hip stem, implant anchorage is very difficult in the proximal femur. This study compares two plate systems regarding their biomechanical properties and the handling in periprosthetic fracture fixation of the proximal femur. Materials and methods Using eight pairs of fresh, frozen human proximal femora the Locking Compression Plate/Locking Attachment Plate construct (LCP/LAP) (group I, DePuy Synthes) was compared to the new LOQTEQ® periprosthetic distal lateral femur plate (group II, AAP Implantate AG). After implantation of press fit femoral hip stems a Vancouver B1 fracture model was used. Biomechanical testing was performed by cyclic axial loading with a constant increment of 0.1 N/cycle starting from 750 N axial loading. Every 250 cycles an a.p. x-ray was done to evaluate failure. Results The Group II showed significant higher axial stiffness (+42%) compared with Group I. In addition, Group II withstood significantly more load-cycles until failure (20%). The mode of catastrophic failure was plate breakage in Group II, whereas, in Group I, all plates showed an early bending followed by plate breakage. Discussion and conclusion Both plate systems enable screw placement around hip stems. The hinge plate showed superior biomechanical results compared with the locking compression plate/locking attachment plate construct. Furthermore, the hinge plate offers variable hinges and variable angel locking making bicortical screw placement around hip stems more comfortable and safe. The translational potential of this article The results of this study can be directly transferred to patient care. With the innovative hinge plate, the surgeon has a biomechanically superior implant, which also offers improved options for screw placement compared to a standard locking plate.

A New System for Periprosthetic Fracture Stabilization—A Biomechanical Comparison

“…However, there were no outliers among the respective study groups A and B. These results align with the context of previous similar studies [7,26,[28][29][30]42], which supports the Hypothesis (H1) that the LOQTEQ ® offers higher stability. In direct comparison to the study by Wähnert et al 2020 [29], the stiffness for the LOQTEQ ® was approximately 3.5 times higher than in our study (253.9 N/mm (SD +/− 46.8) vs. 73.4 N/mm (SD +/− 3.0)).…”

“…Therefore osteotomy was adapted accordingly by establishing a Vancouver B1 fracture with a comminution zone below the tip of the stem. This approach is consistent with most established biomechanical studies [7,16,[22][23][24][25][26][27][28][29][30]. Following radiological determination of the prosthesis tip and drawing of the osteotomy plane, the femurs were cut orthogonal to the femoral shaft axis.…”

“…A longer working length leads to a reduced stiffness of the construct and larger interfragmentary movements in the fracture gap [43,44]. Furthermore, the comparative study determined the axial stiffness over ten cycles (cycles 10 to 19) [28][29][30]. It probably led to the significant discrepancy in stiffness for the LCP ® in his studies from 2014 (47 N/mm +/− 12) [30] and 2020 (145.6 N/mm +/− 27.1) [29] under similar test conditions.…”

“…Furthermore, the comparative study determined the axial stiffness over ten cycles (cycles 10 to 19) [28][29][30]. It probably led to the significant discrepancy in stiffness for the LCP ® in his studies from 2014 (47 N/mm +/− 12) [30] and 2020 (145.6 N/mm +/− 27.1) [29] under similar test conditions. During the data recording, we saw that the stiffness was relatively high or even increasing in the early cycles but then continuously settled in the course of the cyclical testing.…”

Innovative designs and procedures for fracture fixation and soft tissue repair

“…[ 5 ] for meniscal root repairs and the second by Wähnert et al. [ 6 ] for femoral shaft fractures. Animal models have also been used extensively to assess novel surgical techniques before applying them to patients.…”