Treatment of adolescent idiopathic scoliosis (AIS) depends on the magnitude of curve and risk of curve progression. Curve with magnitude less than 20 degrees do not require any treatment and are followed up regularly every 6 months till skeletal maturity. Curves with a magnitude between 20-40 degrees are treated with brace. Those with curves larger than 40 degrees are surgical candidates. Most common presentation of scoliosis is right sided Thoracic curve with Rib hump and higher right shoulder. A few patients develop additional lumbar curve that might be rigid or flexible. These are known as Double curves.
Surgery for AIS is now mostly done through a posterior approach. Previously rigid curves or curves >120 degrees were managed in 2-stages – Anterior release in first stage and a week later second stage with posterior fixation. But with development of current pedicle screws system and neuromonitoring, this 2 stage approach is now obsolete and now almost all can be treated with single stage posterior instrumentation. Neuromonitoring provides constant monitoring of neurology of patient during surgery and helps identify any strain on spinal cord reducing incidence of postoperative deficit.
Treating a Double curve is a surgical challenge and traditionally involves fusing both curves but some cases who fulfill certain radiological and clinical criteria are candidates for Selective Thoracic Fusion (STF). In STF only thoracic curve is fused leaving the flexible Lumbar curve to correct spontaneously. The advantage of STF is reduced length of instrumentation and extent of surgery along with preservation of spine mobility. However strict long term follow up is needed in these cases to monitor progression of lumbar curve.
A 12-year-old girl presented to us with rib hump and shoulder height difference noticed by her mother 9 months back. The problem was progressing with visible deformity. Her X-rays showed double curves – thoracic curve of 40 deg and Lumbar curve of 40 deg. Her lumbar curve was highly flexible correcting to 15 deg on bending films. After careful clinical and radiological examination, the patient was found to satisfy the criteria for Selective Thoracic fusion with posterior pedicle screw fixation and multiple apical Ponte’s osteotomies. Surgery was done under neuromonitoring. Patient tolerated the procedure well and was shifted to ICU for overnight monitoring. She was mobilised after 2 days and discharged in 4 days post surgery. Follow up Xrays showed good correction with balanced spine.
