Lumbar Lordosis Minus Thoracic Kyphosis: Remain Constant in Adolescent Idiopathic Scoliosis Patients Before and After Correction Surgery.

Methods: A retrospective study. Objective: To explore the relationship between the change of lumbar lordosis (LL) and thoracic kyphosis (TK) in AIS patients after correction surgery.

Background: TK tends to decrease in Lenke 1 and Lenke 2 AIS patients after correction surgery using pedicle screws, with the compensation of LL decrease. We hypothesize that lumbar lordosis minus thoracic kyphosis (LL-TK) remains constant after correction surgery to achieve the sagittal balance in AIS patients.

Methods: Medical records of Lenke 1 or Lenke 2 AIS patients who received posterior correction surgery using pedicle screws in our hospital from January 2010 to January 2013 were reviewed. General characters of patients and radiological parameters were evaluated before the surgery and at two years' follow-up. Correlation analysis between TK and LL was conducted. LL-TK and the change of LL and TK were analyzed at preoperation and final follow-up.

Results: A total of 76 Lenke 1 and Lenke 2 AIS patients were included. Both TK and LL decreased significantly after correction surgery (P = 0.019 and P = 0.040, respectively). There were significant correlations between TK and LL before and after surgery, respectively (preoperative: r = 0.234, P = 0.042; postoperative: r = 0.310, P = 0.006). Preoperative and postoperative LL-TK was 23.80° and 25.09°, respectively, and no significant difference of LL-TK was observed (P = 0.372). The same tendency was observed in the change of LL and TK, and significant correlation was also found between the change of TK and LL (r = 0.626, P = 0.002).

Conclusions: The same change of LL and TK and no significant difference in LL-TK indicated that LL-TK might be an important compensatory mechanism in keeping sagittal balance.