Non-parallel screw fixation for femoral neck fractures in young adults

Abstract

The Authors believes this method provides better union rate & less incidence of femoral neck shortening than that of the conventional inverted triangle screws configuration reported in literature. However multi-center studies & long term follow-up is needed to fully evaluate this method.

Biplane Double-supported Screw Fixation of Femoral Neck Fractures: Surgical Technique and Surgical Notes

“…The laboratory results have been confirmed clinically in two recent studies involving a total of 248 patients with displaced femoral neck fractures. 6,7 These clinical studies have revealed better fixation stability with BDSF, resulting in a lower incidence of nonunion (3.4% 6 and 5% 7 ) and a higher rate of fracture union (96.6% 6 and 95% 7 ) compared with literature data for CFIX.…”

“…The nonparallel orientation of the screws does not prevent their sliding in the femoral neck, which can be considered a hollow cylinder from biomechanical point of view. 7…”

“…In contrast to CFIX, BDSF results in a reduced rate of subtrochanteric fractures due to a much bigger distance between the BDSF screw heads (20 to 40 mm), allowing spreading of the tensile forces over a larger area on the lateral cortex and preventing the concentration of stress on a small surface as with CFIX. 6,7 Furthermore, a steeper screw angle that leads to a larger distance between the lateral supporting point (screw entry at the diaphyseal cortex) and the most medial supporting point (on the midcervical line) would further reduce the tension load at the lateral cortex by up to 42% compared with the load with CFIX (ie, beam theory). 4 The rate of subtrochanteric fractures after side fall incidents is approximately 0.3% among the elderly, and the rate of such fractures after conventional internal fixation is 2.4%.…”

“…123 On the basis of recent clinical evidence and experimental results, the novel method of biplane double-supported screw fixation (BDSF) was introduced and deemed to improve substantially the stability of cannulated screws osteosynthesis by implementation of an innovative biomechanical concept. 4567 It is associated with up to 44% higher axial fixation strength in vitro compared with conventional parallel screw fixation (CFIX) and a bone union rate of up to 96.6% in the clinical practice, being much higher compared with the latter. 4567 The concept of biplane positioning facilitates positioning of three medially diverging cannulated screws in steeper angles to the diaphyseal axis.…”

“…4567 It is associated with up to 44% higher axial fixation strength in vitro compared with conventional parallel screw fixation (CFIX) and a bone union rate of up to 96.6% in the clinical practice, being much higher compared with the latter. 4567 The concept of biplane positioning facilitates positioning of three medially diverging cannulated screws in steeper angles to the diaphyseal axis. Two of the screws are with entry points within the thicker cortex of the proximal diaphysis to improve their beam function and lateral cortical support (Figure 1).…”