Adolescent idiopathic scoliosis: fixation of the back by screw or hook fixation?

Surgical treatment of progressive or severe adolescent idiopathic scoliosis (AIS) often consists of posterior spinal fusion. There is still no consensus on the preferred instrumentation technique. Recently, the concept of using all pedicle screw instrumentation has been popularized. Thoracic pedicle screws are generally believed to give a better correction of coronal Cobb angle and vertebral rotation, and to have a higher pull-out strength. However, these studies have poor to fair methodological quality, and at least the clinical relevance of these findings is not clear. In our hospital we haven been using a proximal hook claw construct for years with good results. We hypothesize that proximal fixation of the spondylodesis with a pedicle screw construct gives better coronal Cobb angle correction with less loss of correction compared to a hook claw construct.

Besides, most spinal implants consist of cobalt chromium alloys and titanium. In hip replacement surgery, there are many recent studies reporting elevated serum cobalt and chromium levels in metal-on-metal arthroplasties, which can be potentially dangerous. In spinal surgery, only cross-sectional studies have been carried out with regard to this phenomenon. However, elevated serum metal ion levels can be of importance, because exposure to nonphysiologic levels of chromium can result in genotoxicity, mutagenicity, impaired reproductive function, and infertility.

Proximal fixation of the spondylodesis with a pedicle screw construct gives better coronal Cobb angle correction with less loss of correction compared to a hook claw construct.

pre-operatively, perioperatively, and postoperatively at 6 weeks, 3 months, 6 months, 1 year and 2 years.

Surgical posterior instrumentation and fusion, in accordance with the standard. There will be a randomization between proximal fixation of the instrumentation with a hook claw construct or with a pedicle screw construct. Both surgical treatments are valid options in the standard care of patients with adolescent idiopathic scoliosis.