The effect of implant choice on varus angulation and clinical results in the management of subtrochanteric fractures

Introduction

The aim of this study was to evaluate the effects of implant choice on varus angulation in the management of subtrochanteric fractures.

Methods

Between 2011 and 2016, 58 patients were included in the study and femur locking plate (PF-LCP; Group 1 = 27) and proximal femoral nails (PFN; Group 2 = 31) were compared retrospectively.

Results

In group 1, femoral NSA was measured 131,37 ± 1,95 and last follow-up angle was 127,33 ± 2,40. (p = 0,025). The mean Harris hip score was 67.59 ± 17.74 and 63.29 ± 13.83 in Group 1 and Group 2, respectively (p = 0.406).

Conclusions

Plate fixation is not as successful as proximal nails at preventing varus angulation.

A biomechanical study comparing proximal femur nail and proximal femur locking compression plate in fixation of reverse oblique proximal femur fractures

BACKGROUND

The reverse oblique trochanteric fractures are common fractures and its treatment poses a challenge. The purpose of this study was to compare the biomechanical parameters of the construct using proximal femoral nail (PFN) and proximal femoral locking compression plates (PFLCP) in these fractures using cadaveric specimens.

MATERIALS AND METHODS

Twenty freshly harvested cadaveric femoral specimens were randomly assigned to two groups after measuring bone mineral density, ten of which were implanted with PFN and the other ten with PFLCP. The constructs were made unstable to simulate reverse oblique trochanteric fracture (AO type 31A3.3) by removing a standard size posteromedial wedge. These constructs were tested in a computer controlled cyclic compressive loading with 200kg at a frequency of 1 cycle/s (1Hz) and test was observed for 50,000 cycles or until implant failure, whichever occurred earlier. Peak displacements were measured and analysis was done to determine axial stiffness and subsidence in axial loading.

RESULTS

All the specimens in PFN group completed 50,000 cycles and in PFLCP group, seven specimens completed 50,000 cycles. Average subsidence in PFN group was 1.24±0.22mm and in PFLCP group was 1.48±0.38mm. The average stiffness of PFN group (72.6±6.8N/mm) was significantly higher than of PFLCP group (62.4±4.9N/mm) (P=0.04). The average number of cycles sustained by PFLCP was 46634 and for PFN group was 50,000 (P=0.06).

CONCLUSION

The PFN is biomechanically superior to PFLCP in terms of axial stiffness, subsidence and number of specimens failed for the fixation of reverse oblique trochanteric fractures of femur.