J Korean Neurosurg Soc.  2018 Jan;61(1):75-80. 10.3340/jkns.2016.1212.008.

Freehand S2 Alar-Iliac Screw Placement Using K-Wire and Cannulated Screw: Technical Case Series

• Choi HY
• Hyun SJ
• Kim KJ
• Jahng TA
• Kim HJ

• KMID: 2403526
• DOI: http://doi.org/10.3340/jkns.2016.1212.008

Abstract

OBJECTIVE
Among the various sacropelvic fixation methods, S2 alar-iliac (S2AI) screw fixation has several advantages compared to conventional iliac wing screw. However, the placement of S2AI screw still remains a challenge. The purpose of this study was to describe a novel technique of free hand S2AI screw insertion using a K-wire and cannulated screw, and to evaluate the accuracy of the technique.
METHODS
S2AI screw was inserted by free hand technique in sixteen consecutive patients without any fluoroscopic guidance. The gearshift was advanced to make a pilot hole passing through the sacroiliac joint and directing the anterior inferior iliac spine. A K-wire was placed through the pilot hole. After introducing a cannulated tapper along with the K-wire, a cannulated S2AI screw was installed over the K-wire.
RESULTS
Thirty-three S2AI screws were placed in sixteen consecutive patients. Thirty-two screws were cannulated screws, and one screw was a conventional non-cannulated screw. Thirty out of 32 (93.8%) cannulated screws were accurately positioned, whereas two cannulated screws and one non-cannulated screw violated lateral cortex of the ilium.
CONCLUSION
The technique using K-wire and cannulated screw can provide accurate placement of free hand S2AI screw.

Keyword

S2 alar-iliac screw; Sacropelvic fixation; Free hand technique; Cannulated screw

MeSH Terms

Hand
Humans
Ilium
Sacroiliac Joint
Spine

Figure

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  Fig. 1 A : The gearshift is initially pointed dorsally to avoid anterior wall violation of the pelvic bone. After crossing the sacroiliac joint, the tip is turned ventrally. B : After the pilot hole is created and verified as intraosseous, K-wire is placed through the hole. C : Tapping is performed with a cannulated tap along with the K-wire. D : Cannulated S2 alar-iliac screw is inserted over the K-wire in the same manner.

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  Fig. 2 Anteroposterior and lateral plain radiographs demonstrate S2 alar-iliac (S2AI) screw insertion using cannulated screws. Note the radiolucent line inside the screw (arrows). Two S2AI screws are accurately placed.

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  Fig. 3 A : Anteroposterior plain radiograph of Patient 3. A cannulated S2 alar-iliac (S2AI) screw (arrow) was inserted on the left side, whereas conventional non-cannulated S2AI screw (curved arrow) was inserted on the right side with the additional iliac wing screw (arrowhead). B : Computed tomographic axial image of the same patient demonstrates cortical violation of the lateral ilium by the conventional non-cannulated S2AI screw (curved arrow) and iliac wing screw (arrowhead). Cannulated S2AI screw (arrow) was accurately positioned on the left side.

Reference

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