Selective Fusion in Lenke 5 Adolescent Idiopathic Scoliosis

To compare the clinical and radiographic outcomes on the sagittal plane between anterior and posterior selective fusion (ASF and PSF) in patients with Lenke 5 adolescent idiopathic scoliosis (AIS) for a minimum of 5 years of follow-up.

We included 77 patients with Lenke 5 AIS who underwent ASF (n = 40) with a single rod with structural cages or PSF (n = 37) with pedicle screw instrumentation. Radiographic parameters were compared preoperatively, 3 months and 2 years postoperatively, and at final follow-up.

The mean follow-up duration was 93.9 ± 21.4 months in the ASF group and 80.4 ± 15.2 in the PSF group (P = 0.002). The correction rate of the coronal curve was comparable between the 2 groups at final follow-up. There was a significant time trend for lumbar lordosis (LL), thoracic kyphosis, thoracolumbar junctional kyphosis, instrumented segmental angle (ISA), proximal junctional angle, and sagittal vertical axis (P < 0.001) and significant group effects for LL (P = 0.0065) and ISA (P = 0.0325). At 3 months postoperatively, LL decreased in the ASF group and increased in the PSF group (-3.1° ± 6.6° vs. 1.3° ± 5.5° change, P = 0.002) and increased in both groups at final follow-up (2° ± 2.9° vs. 4.3° ± 4.9° change, P = 0.070). ISA increased in both groups 3 months postoperatively but decreased significantly in the ASF group compared with the PSF group at 2-year follow-up (4.0° ± 3.9° vs. 0.7° ± 1.9° change, P < 0.001) and final follow-up (8.1° ± 5.8° vs. 0.8° ± 3.4° change, P < 0.001). LL, ISA, and proximal junctional angle were significantly larger at final follow-up in the PSF group (P < 0.05). The incidence of proximal junctional kyphosis was higher in the PSF group (5/37) than in the ASF group (1/40).

A significant and continuous loss of lordosis in ISA was observed after ASF in patients with Lenke 5 AIS. A larger LL was obtained with a higher incidence of proximal junctional kyphosis at long-term follow-up after PSF.