Revision by S2-alar-iliac instrumentation reduces caudal screw loosening while improving sacroiliac joint pain\u2014a group comparison study

Sandro M. Krieg,Lucia Albers,Sebastian Ille,Bernhard Meyer,Nico Sollmann

doi:10.1007/s10143-020-01377-1

Sandro M. Krieg, Lucia Albers + Show 3 more

Open Access

https://doi.org/10.1007/s10143-020-01377-1

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Abstract

Lumbosacral instrumentation continues to be challenging due to complex biomechanical force distributions and poor sacral bone quality. Various techniques have therefore been established. The aim of this study was to investigate the outcome of patients treated with S2-alar-iliac (S2AI), S2-alar (S2A), and iliac (I) instrumentation as the most caudal level. Sixty patients underwent one of the 3 techniques between January 2012 and June 2017 (S2AI 18 patients, S2A 20 patients, I 22 patients). Mean age was 70.4 ± 8.5 years. Screw loosening (SL) and sacroiliac joint (SIJ) pain were evaluated during the course at 3-month and maximum follow-up (FU). All patients completed 3-month FU, the mean FU period was 2.5 ± 1.5 years (p = 0.38), and a median of 5 segments was operated on (p = 0.26), respectively. Bone mineral density (BMD), derived opportunistically from computed tomography (CT), did not significantly differ between the groups (p = 0.66), but cages were more frequently implanted in patients of the S2A group (p = 0.04). SL of sacral or iliac screws was more common in patients of the S2A and I groups compared with the S2AI group (S2AI 16.7%, S2A 55.0%, I 27.3% of patients; p = 0.03). SIJ pain was more often improved in the S2AI group not only after 3 months but also at maximum FU (S2AI 61.1%, S2A 25.0%, I 22.7% of patients showing improvement; p = 0.02). Even in shorter or mid-length lumbar or thoracolumbar constructs, S2AI might be considered superior to S2A and I instrumentation due to showing lower incidences of caudal SL and SIJ pain.

Highlights

Instrumentation of the lumbosacral spine continues to be a challenging area in spine surgery, due to complex local anatomy, unique biomechanical force distributions, and comparatively poor sacral bone quality
There is a high rate of screw loosening (SL), instrumentation failure, pseudarthrosis, and sacroiliac joint (SIJ) pain [1,2,3]
Our main findings were that S2AI showed superiority compared with S2A and I techniques in terms of reduced caudal SL and a lower rate of SIJ pain

Summary

Introduction

Instrumentation of the lumbosacral spine continues to be a challenging area in spine surgery, due to complex local anatomy, unique biomechanical force distributions, and comparatively poor sacral bone quality. There is a high rate of screw loosening (SL), instrumentation failure, pseudarthrosis, and sacroiliac joint (SIJ) pain (up to 83%) [1,2,3]. The Galveston technique and iliac screws were the first approaches trying to improve caudal instrumentation by extending the construct down to the pelvis [4, 5]. Iliac screws were proven to be superior to the Galveston technique in terms of construct strength, iliac screws were shown to cause pain due their prominence, ending in revision surgery in about 22% of cases [5, 6]. Instrumentation down to the sacrum puts a long cranial cantilever on the SIJ, reducing the durability of the construct and causing a biomechanical overload and

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