The clinical role of preoperative fulcrum-bending and supine side-bending radiographs on the prediction of curve correction in adolescent idiopathic scoliosis

PURPOSE

Preoperative curve assessment is important in adolescent idiopathic scoliosis (AIS). Our objective is to clarify the role of side-bending radiographs (SBR) and fulcrum-bending radiographs (FBR) in predicting postoperative Cobb angle in nonstructural and structural curves.

METHODS

Twenty-five consecutive patients with AIS who underwent correction surgery were included. The Cobb angles of structural and nonstructural curves were determined. Cobb angles were measured based on pre- and postoperative standing anteroposterior radiographs of the whole spine. The Cobb angles of SBR and FBR were measured preoperatively. The difference between the Cobb angle at each bending and the preoperative Cobb angle was defined as the predicted correction angle, whereas the difference between the preoperative Cobb angle and postoperative Cobb angle was defined as the surgical correction angle. The correction index was calculated by dividing the surgical correction angle by the predicted correction angle. The difference between the predicted correction angle and surgical correction angle was defined as the prediction error. We compared SBR and FBR for both structural and nonstructural curves in these terms.

RESULTS

For both curves, the predicted correction angle of FBR was significantly higher than that of SBR, and the correction index of FBR was significantly lower than that of SBR. Patients with a correction index close to 1 and small prediction error had undergone FBR in the structural curve and SBR in the nonstructural curve.

CONCLUSION

FBR is predictive of postoperative correction angle of the structural curve, whereas SBR is predictive of postoperative correction angle of the nonstructural curve.

Modified fulcrum bending radiography: A new combined technique that may reflect scoliotic curve flexibility better than other conventional methods

BACKGROUND

Numerous techniques for determining the flexibility of the scoliotic cure have been invented. Our contribution includes combining traction and translation forces; we introduced a new radiographic technique that can be claimed to be capable of a far more precise prediction of the scoliotic curve flexibility.

METHODS

In this study, we compared the flexibility rate obtained on standard fulcrum bending radiographs with modified ones in 50 consecutive patients with adolescent idiopathic scoliosis (78 curves) who had referred to our clinics from September 2009 to July 2012. In this new technique, we added traction force to the upside extremities. Then, flexibility rate of the two methods was compared statistically.

RESULTS

The study included 50 cases (43 female and 7 male) aged 10-17 (14.5 ± 2.1 years) comprising 78 scoliotic curves. Curves magnitude varied from 25° to 135° (61.4° ± 21.3°). The mean flexibility rate with standard fulcrum bending radiograph was 38.8% ± 20%. This index increased to 58.3% ± 22.2% (which is statistically significant, p < 0.0005) as a result of implementing the modified fulcrum bending method. Excluding the proximal thoracic curves due to the limited number of the cases, the difference between flexibility rate with this new technique in main thoracic and thoracolumbar/lumbar curves is not statistically significant (p > 0.05).

CONCLUSIONS

The modified fulcrum bending method we introduced has some inevitable disadvantages; however, in the era of modern and vigorous segmental spinal instrumentation, with combining traction and translation forces in their best biomechanical state, it can demonstrate the scoliotic curve flexibility much more efficiently.