To evaluate the effect of a stiffer rod in normalising thoracic hypokyphosis in adolescent idiopathic scoliosis (AIS). A retrospective review of AIS cases performed at our institution was carried out. In order to reduce variability, the analysis included only Lenke 1 cases which had all pedicle screw constructs, with similar constructs and implant density. Cases that underwent anterior release were excluded. All cases had the same implant (Expedium 5.5, Depuy-Synthes, Raynham, USA). The rod material differed in that some cases had 5.5 titanium, whilst others had 5.5 cobalt chrome. The preoperative and postoperative sagittal Cobb angle was measured.Aim:
Methods:
Pedicle screw constructs (PSC) in scoliosis are a recently established and widely accepted method of managing scoliotic curves posteriorly. There is a perceived improved coronal and rotational correction when compared to other posterior only constructs. With continued use of this method, the authors and deformity surgeons in general have become aware of persistent thoracic hypokyphosis. This review of 3 years of scoliosis cases using PSC looks at four different implant strategies utilised to manage this problem and our current practice. These strategies were: All titanium 5.5 mm rod diameter (Expedium, Depuy spine) All titanium 5.5 mm rod diameter with periapical washers (Expedium, Depuy spine) All titanium 6.0 mm rod diameter (Pangea, Synthes) Titanium pedicle screws with 5.5 mm diameter cobalt chrome rods (Expedium Depuy spine) We have reviewed our outcomes with these strategies with respect to thoracic hypokyphosis. Strategy 1 had the highest rate of hypokyphosis on postoperative radiographs. Strategy 4 seems to have the best correction of coronal and sagittal plane abnormality post operatively. As a consequence, our current practice is the use of titanium pedicle screws and 5.5 mm diameter cobalt chrome rods when managing scoliosis with a pedicle screw construct.
