S2 Alar-Iliac Screws in Fixation and Correction of Combined Neuromuscular Spinal and Pelvic Deformities

PURPOSE OF THE STUDY Neuromuscular deformities of the spine represent surgically uneasy to solve problems as well as serious handicaps causing sitting instability, pressure ulcers as well as pain. The aim of our study is to conduct a retrospective clinical analysis of the results of surgical correction of these deformities. This paper presents the use of a recent technique of sacral-alar-iliac (S2AI) screws and its comparison with other techniques of pelvic stabilisation. MATERIAL AND METHODS The group of 41 patients treated surgically with S2AI screws technique and transpedicular or hybrid instrumentation of the spine consisted of patients with the primary diagnosis of muscular dysthrophy, spinal muscular atrophy, cerebral palsy and some other neuromuscular diseases. The results of pelvic obliquity correction and scoliotic correction in combined neuromuscular deformities of the spine and pelvis were analysed. The technique of S2AI screws implantation and the possibility of their free-hand technique implementation were presented. RESULTS In the followed-up group of patients an average correction of pelvic obliquity by 81% (from 29.1 degrees before the operation to 5.6 degrees after the operation) was reported. On average, 74% correction of scoliotic spine deformity was achieved (from 83.3 degrees before the operation to 22.5 degrees after the operation). In both the cases neither a significant loss of correction at the minimum one-year follow-up nor any serious complications associated with grappling of pelvic fixation were observed. DISCUSSION The S2AI screws offer at least the same stability and ability of correction as iliac screws and at the same time they provide significantly better results compared with the older methods of pelvic fixation such as the Galvestone technique. With a good knowledge of the surgical technique and anatomical aspects this technique can be applied in the form of a free-hand technique. Navigation as well as robotic techniques can help with the accurate positioning of the S2AI screw. Transfixation of sacroiliacal syndesmosis in patients with a neuromuscular handicap does not lead to deterioration of their mobility. CONCLUSIONS Simultaneous stabilisation of spine and pelvis makes it possible to achieve a good quality correction of the deformity and good clinical results over a long period of time. It allows for stability of the sitting position of the patients and improves the quality of their lives. Nowadays, the S2AI screws are considered to be biomechanically the best quality pelvic fixation, eliminating subcutaneous prominence of the instrumentation and reducing the risk of skin decubitus.