Interbody cage support improves reconstruction of sagittal balance after anterior selective fusion in Lenke type 5 idiopathic scoliosis patients.

OBJECTIVE: To investigate the effect of interbody cage support on reconstruction of the sagittal profile after anterior selective correction in Lenke type 5 adolescent idiopathic scoliosis (AIS) patients.

METHODS: In this retrospective study, a total of 40 AIS patients with a Lenke type 5 curve who underwent anterior selective fusion (ASF) using a single rod were studied. They were divided into two groups: Group A, bone grafting with an interbody titanium mesh cage (TMC); and Group B, bone grafting without a TMC. There were 19 female and 1 male patient aged 12-18 years in Group A, and 17 female and 3 male patients aged 13-20 years in Group B. All patients were followed up for more than 18 months. The coronal correction of the scoliosis and reconstruction of the sagittal profile were evaluated retrospectively.

RESULTS: By final follow-up, more than 70% correction had been achieved for the primary curve and a spontaneous correction for the secondary curve in both groups. Satisfactory reconstructions on the sagittal plane were also observed. Similar changes were found in Group A and Group B, including increases in thoracic kyphosis, slight changes in thoracolumbar junctional kyphosis, no significant losses of lumbar lordosis, mild increases in proximal junctional measurement, and remarkable lordosis losses in the instrumented segments. With lessening of the sagittal balance and L(1) offset, a significant anterior shift of the C(7) plumb line was noted during follow-up in Group A, indicating a more balanced spine in this group.

CONCLUSION: Anterior selective single rod instrumentation and fusion is a recommended method for Lenke type 5C AIS. A structural interbody cage does not appear to improve the regional profile, nor the profiles in the instrumented area and the adjacent proximal and distal segments; yet could result in a better total balance in the long-term.