Determination of the best point of entry of percutaneous insertion of sacroiliac screws depending on patient positioning for surgery: A cadaveric study.

Abstract

Background: The standard starting point for percutaneous sacroiliac screw insertion was initially determined at the intersection of the line posterior to the anterior superior iliac spine and the line continuing the anatomical axis of the femur. The technique was pioneered in patients lying prone in surgery, although it has been used with patients in the supine position. The optimal starting point for patients in both prone and supine positions remains uncertain.

Objectives: This cadaveric study aimed to determine the best entry point for the percutaneous insertion of sacroiliac screws depending on the patient's positioning for surgery.

Material and methods: Kirschner wires (K-wires) were percutaneously inserted into the sacral body of 8th human cadavers. In addition to the so-called standard sacroiliac screw entry point (point A), points located consecutively 1 cm (point B) and 2 cm (point C) cranially from the point along the line, prolonging the femoral axis were also studied. The K-wires were inserted into the studied entry points on the right side in a supine position and on the left side of the same cadaver in a prone position. The placement of the K-wires was assessed using radiographic imaging and cadaver dissection.

Results: An analysis of the K-wire placement in the supine position revealed incorrect positioning of 100% of the K-wires inserted at entry point A and 87% at entry point B. All the K-wires inserted in the supine position at entry point C were correctly placed. All K-wires inserted in the prone position were correctly positioned.

Conclusions: All 3 studied entry points enabled the correct placement of orthopedic implants for prone position surgery. The best entry point for surgery performed in the supine position was located 2 cm cranially from the standard entry point, along the line prolonging the femoral axis.