Brendon C Mitchell1, David L Skaggs2, Lawrence G Lenke3, Tracey P Bastrom4, Carrie E Bartley4, Peter O Newton5,6,7. 1. Department of Orthopaedic Surgery, University of California - San Diego, San Diego, CA, USA. 2. Department of Orthopedics, Cedars Sinai Hospital, Los Angeles, CA, USA. 3. Department of Orthopaedic Surgery, Columbia University Medical Center, The Spine Hospital at New York Presbyterian, New York, NY, USA. 4. Division of Orthopedics & Scoliosis, Rady Children's Hospital, San Diego, CA, USA. 5. Department of Orthopaedic Surgery, University of California - San Diego, San Diego, CA, USA. pnewton.rady@gmail.com. 6. Division of Orthopedics & Scoliosis, Rady Children's Hospital, San Diego, CA, USA. pnewton.rady@gmail.com. 7. , 3020 Children's Way, MC 5062, San Diego, CA 92123, USA. pnewton.rady@gmail.com.
Abstract
PURPOSE: To identify curve/correction characteristics associated with adding-on at 2 years after posterior spinal fusion (PSF) in Lenke 1/2 AR curves. METHODS: A prospective multicenter registry was queried to identify patients with adolescent idiopathic scoliosis (AIS), Lenke 1/2 AR curves, who underwent PSF with a minimum of 2-year follow-up. Patient characteristics as well as pre- and post- operative radiographic variables were evaluated using Classification and Regression Tree (CART) analysis to determine which factors contribute to adding-on. RESULTS: 253 patients treated with PSF were assessed for adding-on, of which 50 met our adding-on criteria. Univariate analysis revealed adding-on was associated several factors including: post-operative thoracic and lumbar curve magnitude (p > 0.001), first erect (FE) end instrumented vertebra (EIV) angulation (p = 0.009) and EIV translation (p = 0.001), younger age (p = 0.027), Risser stage (p = 0.024), and a more proximal lowest instrumented vertebra (LIV) (p < 0.001). Multivariate CART analysis showed the chance of adding-on was more than 2 times greater (42 vs 16%) when the chosen LIV was translated more than 2.7 cm from the CSVL. When the LIV was within 2.7 cm, the post-op risk of adding-on was increased when the LIV was not perfectly leveled (> 0.5°). CONCLUSION: In Lenke 1 and 2 AR curves, pre-operative LIV translation appears to be an independent risk factor for adding-on; and in those with < 2.7 cm of LIV translation, FE LIV angulation also seems to increase the risk of adding-on. These factors are relevant in determining appropriate LIV selection and aid in identifying patients at risk for developing adding-on.
PURPOSE: To identify curve/correction characteristics associated with adding-on at 2 years after posterior spinal fusion (PSF) in Lenke 1/2 AR curves. METHODS: A prospective multicenter registry was queried to identify patients with adolescent idiopathic scoliosis (AIS), Lenke 1/2 AR curves, who underwent PSF with a minimum of 2-year follow-up. Patient characteristics as well as pre- and post- operative radiographic variables were evaluated using Classification and Regression Tree (CART) analysis to determine which factors contribute to adding-on. RESULTS: 253 patients treated with PSF were assessed for adding-on, of which 50 met our adding-on criteria. Univariate analysis revealed adding-on was associated several factors including: post-operative thoracic and lumbar curve magnitude (p > 0.001), first erect (FE) end instrumented vertebra (EIV) angulation (p = 0.009) and EIV translation (p = 0.001), younger age (p = 0.027), Risser stage (p = 0.024), and a more proximal lowest instrumented vertebra (LIV) (p < 0.001). Multivariate CART analysis showed the chance of adding-on was more than 2 times greater (42 vs 16%) when the chosen LIV was translated more than 2.7 cm from the CSVL. When the LIV was within 2.7 cm, the post-op risk of adding-on was increased when the LIV was not perfectly leveled (> 0.5°). CONCLUSION: In Lenke 1 and 2 AR curves, pre-operative LIV translation appears to be an independent risk factor for adding-on; and in those with < 2.7 cm of LIV translation, FE LIV angulation also seems to increase the risk of adding-on. These factors are relevant in determining appropriate LIV selection and aid in identifying patients at risk for developing adding-on.
Authors: Robert H Cho; Burt Yaszay; Carrie E Bartley; Tracey P Bastrom; Peter O Newton Journal: Spine (Phila Pa 1976) Date: 2012-07-15 Impact factor: 3.468