To compare the ability of fulcrum bend and traction radiographs to predict correction of AIS using screw only implants and to assess the fulcrum bending correction index (FBCI) with a new measurement: the traction correction index (TCI)

Retrospective radiographic analysis of case series (Level IV)

Radiographic correction of scoliosis based on correction rate does not take into consideration the curve flexibility. It has been suggested that fulcrum bending radiographs predict curve correction in AIS [1]. This has been questioned [2] and has been suggested that traction radiographs are more predictive in a mixed group of patients with hybrid and screw only constructs.

Twenty three patients average age 15, who underwent posterior correction of scoliosis using pedicle screw only construct.

Analysis was carried out on the pre-op and immediate post-op AP radiographs and the pre-op fulcrum bend and traction radiographs. Correction rate, fulcrum flexibility, traction flexibility, FBCI and TCI was calculated.

Preoperative mean Cobb angle of 66 degrees was corrected to 25 degrees postoperatively. The mean fulcrum bending Cobb angle was 38 degrees and traction Cobb angle 28 degrees. The mean fulcrum flexibility was 45%, traction flexibility 59% and correction rate 63%. The mean FBCI was 182% and TCI was112%.

When comparing fulcrum bend and traction radiographs, we found the latter to be more predictive of curve correction in AIS using pedicle screw constructs. The TCI better takes into account the curve flexibility than the FBCI.