Is Primary Fixation with the Sliding Hip Screw Introduced into the Non-ideal Position Sufficient for Stable Pertrochanteric Fracture Stabilisation? A Biomechanical Evaluation and Experimental Study

Abstract

Purpose: Proximal femoral fractures are most commonly sustained fractures in the elderly. The one of the current treatment option of stable pertrochanteric fracture is Sliding Hip Screw. The necessity of a repeat surgery, due to the failure of the first osteosynthesis, may jeopardize the patient's life. Common causes of a failure include: fracture pattern, implant position, implant's properties and the bone quality. Each screw position variant results in damage to various load-bearing bone structures during healing. The aim of this study was analysis of different screw positions with focuse on the risky position with the need of the intra-operative implant reintroduction.
Methods: With the use of a numerical computational model and finite element methods, the authors analyzed five positions of Sliding Hip Screw in the proximal femur, with the objective of determining positions with an increased risk of failure. The ideal position was in the middle third of the femoral neck anchored subchondrally.
Results: In model situations, it has been shown that in stable fractures the screw position in proximal third of the femoral neck significantly increased the strain of the plate and screw and may lead to the osteosynthesis failure. The other analysed positions do not significantly increase the risk of failure for entire fixation.
Conclusions: It is not necessary to re-introduce Sliding Hip Screw into the ideal position (except placening in the proximal third of the neck) during the surgery. Damage to load-bearing structures relative to various implant placements does not impact the resultant overall fixation stability.