Reciprocal Change of Cervical Spine after Posterior Spinal Fusion for Lenke Type 1 and 2 Adolescent Idiopathic Scoliosis

Abstract

Reciprocal sagittal alignment changes after adolescent idiopathic scoliosis (AIS) posterior corrective surgery have been reported in the cervical spine, but the evidence is not yet sufficient. Furthermore, much remains unknown about the effects of cervical kyphosis on clinical outcomes in AIS. Forty-five consecutive patients (4 males and 41 females) with AIS and Lenke type 1 or 2 curves underwent a posterior spinal fusion, and a minimum of 24-month follow-up was collected from our prospective database. We investigated radiographic parameters and SRS-22r. Before surgery, cervical kyphosis (cervical lordosis < 0°) was present in 89% and cervical hyperkyphosis (cervical lordosis < -10°) in 60%. There were no significant differences in age, sex, or Lenke type between the hyperkyphosis and the non-hyperkyphosis groups. Although cervical lordosis increased significantly after surgery, cervical kyphosis was observed in 73% of patients 2 years after surgery. We found a significant correlation between Δthoracic kyphosis (TK) and Δcervical lordosis. Preoperative cervical kyphosis, ΔT1 slope, and ΔTK were independently associated factors for postoperative cervical hyperkyphosis. The cervical hyperkyphosis group had significantly lower SRS-22r domains. In AIS corrective surgery, restoring TK leading to a gain of T1 slope may lead to an improvement of cervical sagittal alignment. Remaining cervical hyperkyphosis after AIS surgery may affect clinical outcomes.

Keywords: Lenke type 1; Lenke type 2; SRS-22r; T1 slope; adolescent idiopathic scoliosis; cervical hyperkyphosis; cervical kyphosis; cervical sagittal alignment; quality of life; reciprocal change.

Figure 1

Pre- (A,B) and post- (C,D) operative radiographs of representative case with 16-year-old male patient. Cases of preoperative cervical kyphosis changed to postoperative cervical lordosis. Cervical lordosis (−5°, 18°), thoracic kyphosis (12°, 15°), lumbar lordosis (48°, 42°), T1 slope (11°, 22°), major thoracic curve (53°, 18°). (Preoperative, postoperative).

Figure 2

Pre- (A,B) and post- (C,D) operative radiographs of representative case with 17-year-old female patient. Cases of preoperative cervical hyperkyphosis changed to postoperative cervical kyphosis. Cervical lordosis (−19°, −8°), thoracic kyphosis (20°, 26°), lumbar lordosis (59°, 64°), T1 slope (11°, 12°), major thoracic curve (78°, 18°). (Preoperative, postoperative).

Figure 3

Pre- (A,B) and post- (C,D) operative radiographs of representative case with 12-year-old female patient. Cases of preoperative cervical lordosis changed to postoperative cervical lordosis. Cervical lordosis (1°, 23°), thoracic kyphosis (21°, 20°), lumbar lordosis (44°, 46°), T1 slope (13°, 19°), major thoracic curve (43°, 2°). (Preoperative, postoperative).

Figure 4

Pre- (A,B) and post- (C,D) operative radiographs of representative case with 20-year-old female patient. Cases of preoperative cervical hyperkyphosis changed to postoperative cervical lordosis. Cervical lordosis (−15°, 3°), thoracic kyphosis (20°, 28°), lumbar lordosis (59°, 52°), T1 slope (9°, 15°), major thoracic curve (51°, 17°). (Preoperative, postoperative).

Figure 5

Pre- (A,C,E,G) and post- (B,D,F,H) operative magnified radiographs of the cervical spine from the cases in Figure 1 (A,B), Figure 2 (C,D), Figure 3 (E,F), and Figure 4 (G,H).