An innovative fulcrum-bending radiographical technique to assess curve flexibility in patients with adolescent idiopathic scoliosis.

Study Design: A prospective clinical and radiographical study.

Objective: To introduce a redesigned fulcrum-bending radiographical (FBR) method, and to validate the effectiveness of this method in assessing patients with (AIS).

Summary Of Background Data: Several radiographical methods exist to evaluate curve flexibility in patients with AIS. The technique of FBR has been demonstrated to better predict coronal plane correction of main thoracic curves. However, the amount of weight applied may affect the results of flexibility evaluation and have not been well studied to date.

Methods: Seventeen patients with AIS with 19 curves were involved in this study. The assessment of radiographs included preoperative standing posterior-anterior, supine side-bending, traditional FBR, new FBR (CH-FBR), and postoperative standing posterior-anterior radiographs. CH-FBR was performed at variable device heights while measuring the applied weight at the apex.

Results: Preoperatively, the mean Cobb angle was 47.5° ± 8.8° on the posterior-anterior radiographs, 14.3° ± 7.0° on supine side-bending radiographs, 13.3° ± 5.7° on traditional FBR, 11.3° ± 4.5° at the lowest height using CH-FBR (lowest weight), and 7.8° ± 4.1° at the optimized height using CH-FBR (maximal weight). Postoperatively, the mean Cobb angle was 9.1° ± 5.2°. There was a significant difference found between supine side-bending radiograph and postoperative Cobb angle (P = 0.001), traditional FBR, and postoperative Cobb angle (P = 0.002). There was no significant difference found between optimized height CH-FBR and postoperative Cobb angle (P = 0.16). Correlation analysis indicated that the maximum height of CH-FBR positively correlated with maximum weight applied (r = 0.68, r= 0.46, P = 0.001).

Conclusion: CH-FBR is a more reliable and effective method than traditional FBR and supine side-bending radiographs to measure curve flexibility in patients with AIS. Moreover, the flexibility suggested by the CH-FBRs more closely approximated the postoperative results from posterior pedicle screw instrumentation.

Level Of Evidence: 3.