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Evaluation of implant loosening following segmental pedicle screw fixation in adolescent idiopathic scoliosis: a 2 year follow-up with low-dose CT

BACKGROUND: The long term radiological status of screw fixation following scoliosis surgery with all pedicle screw construct is not previously studied. AIM: To evaluate the incidence of loosening (implant failure) evaluated with low-dose CT two years following scoliosis surgery. STUDY DESIGN: Retros...

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Detalles Bibliográficos
Autores principales: Abul-Kasim, Kasim, Ohlin, Acke
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4149778/
https://www.ncbi.nlm.nih.gov/pubmed/25177357
http://dx.doi.org/10.1186/1748-7161-9-13
Descripción
Sumario:BACKGROUND: The long term radiological status of screw fixation following scoliosis surgery with all pedicle screw construct is not previously studied. AIM: To evaluate the incidence of loosening (implant failure) evaluated with low-dose CT two years following scoliosis surgery. STUDY DESIGN: Retrospective study. METHODS: 81 consecutive patients with adolescent idiopathic scoliosis (AIS), aged 18 ± 3 years at 2 years follow-up (83% were female), subjected for scoliosis corrective surgery with all pedicle screw construct (total of 1666 screws) has been examined with plain radiography and with low dose CT 6 weeks and 2 years postoperatively. RESULTS: In 26 out of 81 (32%) patients there were signs of loosening of one or more screws, a maximum 3 screws. 47 out of 1666 (2.8%) screws showed evidence of loosening. Preoperative Cobb angle was 56° among patients with loosening compared with 53° among patients with no evidence of loosening (P = 0.288). In males there were signs of loosening in 8 out of 14 (57%) and in females 18 out of 67 (27%), (P = 0.027). Among cases with loosening, 14% had suboptimal screw placement at the first postoperative CT compared with 11% among patients with no evidence of loosening (P = 0.254). One patient with a loosened L4 screw had neurological deficit and subjected for revision of the construct. Out of 26 patients with evidence of loosening, 5 patients reported minor pain or discomfort, 1 patient had a minor proximal junctional kyphosis of about 15° and 3 patients showed evidence of pull-out of 3–5 mm at the upper end of the construct but no clinical complaint. With plain radiography loosening could be observed only in 11 out of 26 cases, 5 were in the lumbar region. CONCLUSIONS: In a consecutive series of 81 cases with AIS who had underwent scoliosis surgery, one third showed, 2 years after the intervention, minor screw loosening. Males were more prone to develop screw loosening. In CT system that enables low-dose protocol, CT is recommended for the evaluation of evidence of screw loosening.