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[degree sign] among patients with loosening compared with 53[degree sign] 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[degree sign] 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.
Author: Kasim Abul-KasimAcke Ohlin
Credits/Source: Scoliosis 2014, 9:13
Published on: 2014-08-24
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