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.
Similar content being viewed by others
References
de Kleuver M, Lewis SJ, Germscheid NM et al (2014) Optimal surgical care for adolescent idiopathic scoliosis: an international consensus. Eur Spine J 23:2603–2618
Martin CT, Pugely AJ, Gao Y et al (2014) Increasing hospital charges for adolescent idiopathic scoliosis in the United States. Spine (Phila Pa 1976) 39:1676–1682
Lonner BS, Auerbach JD, Estreicher MB et al (2009) Thoracic pedicle screw instrumentation: the learning curve and evolution in technique in the treatment of adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 34:2158–2164
Quan GM, Gibson MJ (2010) Correction of main thoracic adolescent idiopathic scoliosis using pedicle screw instrumentation: does higher implant density improve correction? Spine (Phila Pa 1976) 35:562–567
Roach JW, Mehlman CT, Sanders JO (2011) Does the outcome of adolescent idiopathic scoliosis surgery justify the rising cost of the procedures? J Pediatr Orthop 31:S77–80
Clements DH, Betz RR, Newton PO et al (2009) Correlation of scoliosis curve correction with the number and type of fixation anchors. Spine (Phila Pa 1976) 34:2147–2150
Larson AN, Polly DW Jr, Diamond B et al (2014) Does higher anchor density result in increased curve correction and improved clinical outcomes in adolescent idiopathic scoliosis? Spine (Phila Pa 1976) 39:571–578
Sanders JO, Diab M, Richards SB et al (2011) Fixation points within the main thoracic curve: does more instrumentation produce greater curve correction and improved results? Spine (Phila Pa 1976) 36:E1402–E1406
Yang S, Jones-Quaidoo SM, Eager M et al (2011) Right adolescent idiopathic thoracic curve (Lenke 1 A and B): does cost of instrumentation and implant density improve radiographic and cosmetic parameters? Eur Spine J 20:1039–1047
Bharucha NJ, Lonner BS, Auerbach JD et al (2013) Low-density versus high-density thoracic pedicle screw constructs in adolescent idiopathic scoliosis: do more screws lead to a better outcome? Spine J 13:375–381
Li M, Shen Y, Fang X et al (2009) Coronal and sagittal plane correction in patients with Lenke 1 adolescent idiopathic scoliosis: a comparison of consecutive versus interval pedicle screw placement. J Spinal Disord Tech 22:251–256
Tsirikos AI, Subramanian AS (2012) Posterior spinal arthrodesis for adolescent idiopathic scoliosis using pedicle screw instrumentation: does a bilateral or unilateral screw technique affect surgical outcome? J Bone Joint Surg Br 94:1670–1677
Clement JL, Chau E, Kimkpe C et al (2008) Restoration of thoracic kyphosis by posterior instrumentation in adolescent idiopathic scoliosis: comparative radiographic analysis of two methods of reduction. Spine (Phila Pa 1976) 33:1579–1587
Vora V, Crawford A, Babekhir N et al (2007) A pedicle screw construct gives an enhanced posterior correction of adolescent idiopathic scoliosis when compared with other constructs: myth or reality. Spine (Phila Pa 1976) 32:1869–1874
Fletcher ND, Hopkins J, McClung A et al (2012) Residual thoracic hypokyphosis after posterior spinal fusion and instrumentation in adolescent idiopathic scoliosis: risk factors and clinical ramifications. Spine (Phila Pa 1976) 37:200–206
Morr S, Carrer A, Alvarez-Garcia de Quesada LI et al (2015) Skipped versus consecutive pedicle screw constructs for correction of Lenke 1 curves. Eur Spine J 24(7):1473–1480
Lamerain M, Bachy M, Delpont M et al (2014) CoCr rods provide better frontal correction of adolescent idiopathic scoliosis treated by all-pedicle screw fixation. Eur Spine J 23:1190–1196
Aubin CE, Labelle H, Ciolofan OC (2007) Variability of spinal instrumentation configurations in adolescent idiopathic scoliosis. Eur Spine J 16:57–64
Kamerlink JR, Quirno M, Auerbach JD et al (2010) Hospital cost analysis of adolescent idiopathic scoliosis correction surgery in 125 consecutive cases. J Bone Joint Surg Am 92:1097–1104
Sun YQ, Samartzis D, Cheung KM et al (2011) The “X-Factor” index: a new parameter for the assessment of adolescent idiopathic scoliosis correction. Eur Spine J 20:144–150
Tao F, Zhao Y, Wu Y et al (2010) The effect of differing spinal fusion instrumentation on the occurrence of postoperative crankshaft phenomenon in adolescent idiopathic scoliosis. J Spinal Disord Tech 23:e75–80
Muschik M, Schlenzka D, Robinson PN et al (1999) Dorsal instrumentation for idiopathic adolescent thoracic scoliosis: rod rotation versus translation. Eur Spine J 8:93–99
Kuklo TR, Potter BK, Polly DW Jr et al (2005) Monaxial versus multiaxial thoracic pedicle screws in the correction of adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 30:2113–2120
Wang X, Aubin CE, Robitaille I et al (2012) Biomechanical comparison of alternative densities of pedicle screws for the treatment of adolescent idiopathic scoliosis. Eur Spine J 21:1082–1090
Salmingo RA, Tadano S, Fujisaki K et al (2013) Relationship of forces acting on implant rods and degree of scoliosis correction. Clin Biomech (Bristol, Avon) 28:122–128
Min K, Sdzuy C, Farshad M (2013) Posterior correction of thoracic adolescent idiopathic scoliosis with pedicle screw instrumentation: results of 48 patients with minimal 10-year follow-up. Eur Spine J 22:345–354
Le Naveaux F, Aubin CE, Larson AN et al (2015) Implant distribution in surgically instrumented Lenke 1 adolescent idiopathic scoliosis: does it affect curve correction? Spine (Phila Pa 1976) 40:462–468
Bago J, Perez-Grueso FJ, Les E et al (2009) Minimal important differences of the SRS-22 Patient Questionnaire following surgical treatment of idiopathic scoliosis. Eur Spine J 18:1898–1904
Lonner BS, Lazar-Antman MA, Sponseller PD et al (2012) Multivariate analysis of factors associated with kyphosis maintenance in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 37:1297–1302
Suk SI, Lee CK, Kim WJ et al (1995) Segmental pedicle screw fixation in the treatment of thoracic idiopathic scoliosis. Spine (Phila Pa 1976) 20:1399–1405
Conflict of interest
The authors declare that they have no conflict of interest.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Rushton, P.R.P., Elmalky, M., Tikoo, A. et al. The effect of metal density in thoracic adolescent idiopathic scoliosis. Eur Spine J 25, 3324–3330 (2016). https://doi.org/10.1007/s00586-015-4335-x
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00586-015-4335-x