Paul R P Rushton1, Mahmoud Elmalky2, Agnivesh Tikoo3, Saumyajit Basu3, Ashley A Cole4, Michael P Grevitt5. 1. Centre for Spinal Studies and Surgery, Queen's Medical Centre, Nottingham, NG7 2UH, UK. paulrushton@doctors.org.uk. 2. Faculty of Medicine, Menoufia University, Al Minufya, Egypt. 3. Park Clinic, 4 Gorky Terrace, Kolkata, India. 4. Sheffield Children's Hospital, Western Bank, Sheffield, S10 2TH, UK. 5. Centre for Spinal Studies and Surgery, Queen's Medical Centre, Nottingham, NG7 2UH, UK.
Abstract
PURPOSE: Determine impact of metal density on curve correction and costs in thoracic adolescent idiopathic scoliosis (AIS). Ascertain if increased metal density is required for larger or stiffer curves. METHODS: Multicentre retrospective case series of patients with Lenke 1-2 AIS treated with single-stage posterior only surgery using a standardized surgical technique; constructs using >80 % screws with variable metal density. All cases had >2-year follow up. Outcomes measures included coronal and sagittal radiographic outcomes, metal density (number of instrumented pedicles vs total available), fusion length and cost. RESULTS: 106 cases included 94 female. 78 Lenke 1. Mean age 14 years (9-26). Mean main thoracic (MT) Cobb angle 63° corrected to 22° (66 %). No significant correlations were present between metal density and: (a) coronal curve correction rates of the MT (r = 0.13, p = 0.19); (b) lumbar curve frontal correction (r = -0.15, p = 0.12); (c) correction index in MT curve (r = -0.10, p = 0.32); and (d) correction index in lumbar curve (r = 0.11, p = 0.28). Metal density was not correlated with change in thoracic kyphosis (r = 0.22, p = 0.04) or lumbosacral lordosis (r = 0.27, p = 0.01). Longer fusions were associated with greater loss of thoracic kyphosis (r = -0.31, p = 0.003). Groups differing by preoperative curve size and stiffness had comparable corrections with similar metal density. The pedicle screw cost represented 21-29 % of overall cost of inpatient treatment depending on metal density. CONCLUSIONS: Metal density affects cost but not the coronal and sagittal correction of thoracic AIS. Neither larger nor stiffer curves necessitate high metal density.
PURPOSE: Determine impact of metal density on curve correction and costs in thoracic adolescent idiopathic scoliosis (AIS). Ascertain if increased metal density is required for larger or stiffer curves. METHODS: Multicentre retrospective case series of patients with Lenke 1-2 AIS treated with single-stage posterior only surgery using a standardized surgical technique; constructs using >80 % screws with variable metal density. All cases had >2-year follow up. Outcomes measures included coronal and sagittal radiographic outcomes, metal density (number of instrumented pedicles vs total available), fusion length and cost. RESULTS: 106 cases included 94 female. 78 Lenke 1. Mean age 14 years (9-26). Mean main thoracic (MT) Cobb angle 63° corrected to 22° (66 %). No significant correlations were present between metal density and: (a) coronal curve correction rates of the MT (r = 0.13, p = 0.19); (b) lumbar curve frontal correction (r = -0.15, p = 0.12); (c) correction index in MT curve (r = -0.10, p = 0.32); and (d) correction index in lumbar curve (r = 0.11, p = 0.28). Metal density was not correlated with change in thoracic kyphosis (r = 0.22, p = 0.04) or lumbosacral lordosis (r = 0.27, p = 0.01). Longer fusions were associated with greater loss of thoracic kyphosis (r = -0.31, p = 0.003). Groups differing by preoperative curve size and stiffness had comparable corrections with similar metal density. The pedicle screw cost represented 21-29 % of overall cost of inpatient treatment depending on metal density. CONCLUSIONS:Metal density affects cost but not the coronal and sagittal correction of thoracic AIS. Neither larger nor stiffer curves necessitate high metal density.
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