Coronal and Sagittal Plane Correction in Patients With Lenke 1 Adolescent Idiopathic Scoliosis

Li, Ming; Shen, Yu; Fang, Xiutong; Ni, Jianqiang; Gu, Song; Zhu, Xiaodong; Zhang, Zhe

doi:10.1097/bsd.0b013e3181884940

Cited by 59 publications

(43 citation statements)

References 24 publications

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“…This finding agrees well with previous clinical reports [9,12] suggesting that interval pedicle screw placement constructs seem to be equally effective as consecutive constructs for facilitating curve correction in patients with Lenke 1 AIS [12]; higher implant density did not improve curve correction for patients with AIS operated by a single surgeon using an identical surgical technique and type of instrumentation [9]. However, a significant correlation has been found between the number of implants and the curve correction using a multi-center database of AIS patients [11].…”

Section: Discussionsupporting

confidence: 94%

“…In order to apply certain correction techniques and to have a better control on the deformed spine, there has been a noticeable trend among spine surgeons to use more and more pedicle screws [9][10][11]. Nowadays, pedicle screws are frequently placed bilaterally at each vertebra included in the fusion, but some surgeons recommend fewer screws [12]. In spite of the demonstrated benefits of pedicle screws, the associated complications, risks, and the hardware costs are not negligible [13,14].…”

Section: Introductionmentioning

confidence: 99%

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Biomechanical comparison of alternative densities of pedicle screws for the treatment of adolescent idiopathic scoliosis

2011

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Purpose The objective of this computational study was to compare the biomechanical effects of different implant densities in terms of curve reduction and the force levels at the implant-vertebra interface and on the intervertebral elements. Methods Eight cases were randomly picked among patients who have undergone a posterior spinal instrumentation for adolescent idiopathic scoliosis (AIS). For each case, two computer simulations were performed, one with the actual surgery implant pattern and another with the same fusion levels but an alternative implant pattern proposed by an experienced surgeon. The two implant patterns for each case were respectively put into higher and lower implant density group. The spinal correction and the force levels at bone-implant interface and on the intervertebral elements were analyzed and compared between the two groups. Results There were on average 13% more pedicle screws and 30% more bilaterally placed pedicle screws in the higher versus lower density group. The difference in the density of screws (92% vs. 79%) did not lead to significant difference in terms of the resulting main thoracic (MT) Cobb angle, and the MT apical axial vertebral rotation. The average and maximum implant-vertebra force levels were about 50 and 65%, respectively higher in the higher versus lower density group, but without consistent distribution patterns. The average intervertebral forces did not significantly differ between the two groups. Conclusions With the same fusion levels, lower density screws allowed achieving similar deformity correction and it was more likely to have lower screw-vertebra loads.

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Section: Discussionsupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Biomechanical comparison of alternative densities of pedicle screws for the treatment of adolescent idiopathic scoliosis

2011

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“…3, 10,16,38 Although most surgeons would agree that placing 2 pedicle screws at every level fused is usually unnecessary for coronal curve correction, 4,7,17,21,25 the optimal implant density remains unknown. Especially when the sagittal plane has to be taken into consideration, to the best of our knowledge, insufficient evidence of optimal implant density is available to help with decision making.…”

mentioning

confidence: 99%

Main thoracic curve adolescent idiopathic scoliosis: association of higher rod stiffness and concave-side pedicle screw density with improvement in sagittal thoracic kyphosis restoration

Liu

Li²,

Li³

et al. 2015

SPI

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OBJECT The aim of this study was to evaluate the effects of rod stiffness and implant density on coronal and sagittal plane correction in patients with main thoracic curve adolescent idiopathic scoliosis (AIS). METHODS The authors conducted a retrospective study of 77 consecutive cases involving 56 female and 21 male patients with Lenke Type 1 main thoracic curve AIS who underwent single-stage posterior correction and instrumented spinal fusion with pedicle screw fixation between July 2009 and July 2012. The patients' mean age at surgery was 15.79 ± 3.21 years. All patients had at least 1 year of follow-up. Radiological parameters in the coronal and sagittal planes, including Cobb angle of the major curve, side-bending Cobb angle of the major curve, thoracic kyphosis (TK), correction rates, and screw density, were measured and analyzed. Screw densities (calculated as number of screws per fusion segment × 2) of < 0.60 and ≥ 0.60 were defined as low and high density, respectively. Titanium rods of 5.5 mm and 6.35 mm diameter were defined as low and high stiffness, respectively. Patients were divided into 4 groups based on the type of rod and density of screw placement that had been used: Group A, low-stiffness rod with low density of screw placement; Group B, low-stiffness rod with high density of screw placement; Group C, high-stiffness rod with low density of screw placement; Group D, high-stiffness rod with high density of screw placement. RESULTS The mean coronal correction rate of the major curve, for all 77 patients, was (81.45% ± 7.51%), and no significant difference was found among the 4 groups (p > 0.05). Regarding sagittal plane correction, Group A showed a significant decrease in TK after surgery (p < 0.05), while Group D showed a significant increase (p < 0.05); Group B and C showed no significant postoperative changes in TK (p > 0.05). The TK restoration rate was highest in Group D and lowest in Group A (A, −39.32% ± 7.65%; B, −0.37% ± 8.25%; C, −4.04% ± 6.77%; D, 37.59% ± 8.53%). Screw density on the concave side was significantly higher than that on the convex side in all the groups (p < 0.05). CONCLUSIONS For flexible main thoracic curve AIS, both rods with high stiffness and those with low stiffness combined with high or low screw density could provide effective correction in the coronal plane; rods with high stiffness along with high screw density on the concave side could provide better outcome with respect to sagittal TK restoration.

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“…In the literature, the lowest mean implant density reported to have successful results is 1.06 screws per level fused. 21,32,34,50 Thus, 1.06 screws per level fused was then defined as very low implant density. Multiple models were considered.…”

Section: Methodsmentioning

confidence: 99%

“…57 Other studies of predominantly screw constructs have not found a significant difference in curve correction or other parameters. 32,34,48,50 conclusions Should low and high screw-density patterns be determined to have similar clinical and radiographic results, as shown by this model, even a modest reduction in the number of screws may result in significant cost savings of 4% to 7% for the payer. In addition, fewer malpositioned screws and a decreased return to surgery for screw malposition may improve patient safety and the quality of surgical care.…”

Section: Additional Literature On the Cost Savings From Using Low Impmentioning

confidence: 99%

What would be the annual cost savings if fewer screws were used in adolescent idiopathic scoliosis treatment in the US?

Larson

Polly

Ackerman

et al. 2016

SPI

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OBJECT There is substantial heterogeneity in the number of screws used per level fused in adolescent idiopathic scoliosis (AIS) surgery. Assuming equivalent clinical outcomes, the potential cost savings of using fewer pedicle screws were estimated using a medical decision model with sensitivity analysis. METHODS Descriptive analyses explored the annual costs for 5710 AIS inpatient stays using discharge data from the 2009 Kids’ Inpatient Database (Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality), which is a national all-payer inpatient database. Patients between 10 and 17 years of age were identified using the ICD-9-CM code for idiopathic scoliosis (737.30). All inpatient stays were assumed to represent 10-level fusions with pedicle screws for AIS. High screw density was defined at 1.8 screws per level fused, and the standard screw density was defined as 1.48 screws per level fused. The surgical return for screw malposition was set at $23,762. A sensitivity analysis was performed by varying the cost per screw ($600–$1000) and the rate of surgical revisions for screw malposition (0.117%–0.483% of screws; 0.8%–4.3% of patients). The reported outcomes include estimated prevented malpositioned screws (set at 5.1%), averted revision surgeries, and annual cost savings in 2009 US dollars, assuming similar clinical outcomes (rates of complications, revision) using a standard- versus high-density pattern. RESULTS The total annual costs for 5710 AIS hospital stays was $278 million ($48,900 per patient). Substituting a high for a standard screw density yields 3.2 fewer screws implanted per patient, with 932 malpositioned screws prevented and 21 to 88 revision surgeries for implant malposition averted, and a potential annual cost savings of $11 million to $20 million (4%–7% reduction in the total cost of AIS hospitalizations). CONCLUSIONS Reducing the number of screws used in scoliosis surgery could potentially decrease national AIS hospitalization costs by up to 7%, which may improve the safety and efficiency of care. However, such a screw construct must first be proven safe and effective.

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Coronal and Sagittal Plane Correction in Patients With Lenke 1 Adolescent Idiopathic Scoliosis

Abstract: Interval pedicle screw placement constructs seem to be equally effective as consecutive constructs for facilitating curve correction in patients with Lenke 1 AIS.

Cited by 59 publications

References 24 publications

Biomechanical comparison of alternative densities of pedicle screws for the treatment of adolescent idiopathic scoliosis

Biomechanical comparison of alternative densities of pedicle screws for the treatment of adolescent idiopathic scoliosis

Main thoracic curve adolescent idiopathic scoliosis: association of higher rod stiffness and concave-side pedicle screw density with improvement in sagittal thoracic kyphosis restoration

What would be the annual cost savings if fewer screws were used in adolescent idiopathic scoliosis treatment in the US?

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