OBJECTIVES: The recent advancements in spine fixation aid in the treatment of complex spinal pathologies. Both the iliac screw (IS) and the S2-alar-iliac (S2AI) screw provide adequate stability in the fixation of complex lumbosacral spine pathologies, leading to a significant increased rate of using these techniques in the daily practice of the spine surgeons. This study aims to analyze, describe, and compare the insertion and positioning parameters of the S2AI screw and IS techniques in children without spinal deformities. METHODS: An observational retrospective study was conducted at a university hospital in 2018, with 25 computed tomography (CT) images selected continuously. Mann-Whitney-Shapiro-Wilk tests were performed. The reliability of the data was assessed using the intraclass correlation. The data were stratified by age group only for Pearson’s correlation analysis. RESULTS: The mean age was 11.7 years (4.5 SD). The mean IS length was 106.63 mm (4.59 SD). The mean length of the S2AI screw was 104.13 mm (4.22 SD). The mean skin distance from the IS entry point was 28.13 mm (4.27 SD) and that for the S2AI screw was 39.96 mm (4.54 SD). CONCLUSIONS: Through CT, the S2AI screw trajectory was observed to have a greater bone thickness and skin distance than the IS. There was a linear correlation between age and screw length for both techniques. A similar relationship was observed between skin distance and age for the S2AI screw technique. In children, the S2AI screw technique presents advantages such as greater cutaneous coverage and implant thickness than the IS technique.

RESUMO Objetivo: Avaliar, retrospectivamente, os resultados preliminares do pós-operatório de pacientes com displasia do desenvolvimento do quadril, tratados com osteotomia acetabular do tipo Dega modificada e, dessa forma, confirmar a eficácia da técnica. Métodos: Neste estudo retrospectivo foram incluídos pacientes com idades acima de 18 meses. No total, 19 quadris foram submetidos à osteotomia de Dega modificada. Resultados: Os resultados foram satisfatórios, com diminuição média do índice acetabular de 39,2 para 20,6 graus. A média final do ângulo centro-borda foi de 29,6 graus. Em todos os casos houve restabelecimento da congruência articular dos quadris e, até o momento, um caso apresentou necrose da cabeça do fêmur no mesmo período do seguimento. Conclusão: A osteotomia de Dega modificada demonstrou bons resultados iniciais e potencial para ser empregada no tratamento da displasia do desenvolvimento do quadril. Nível de Evidência IV; Série de casos.

ABSTRACT Objective: To retrospectively evaluate the preliminary postoperative results of modified Dega-type acetabular osteotomy to treat developmental dysplasia of the hip, confirming the efficacy and reproducibility of this technique. Methods: This retrospective study included patients older than 18 months. A total of 19 hips underwent modified Dega osteotomy. Results: Satisfactory results were obtained, with an average decrease of the acetabular index from 39.2 to 20.6 degrees. The final average center edge angle was 29.6 degrees. Hip joint congruence was reestablished in all cases, and as of this writing, only one case developed necrosis in the femoral head during follow-up. Conclusion: Modified Dega osteotomy demonstrated good initial results, as well as the potential for use in treating developmental dysplasia of the hip. Level of Evidence IV; Case series.