Spine Surgery, Drum Tower Hospital, Nanjing University, CHINA

Xu SUN, MD, Lei-Lei XU, MS, Feng ZHU, MD, Qi DING, MS,

Zezhang ZHU, MD, Bin WANG, MD, Bang-ping QIAN, MD,

Yang YU, MD, Yong QIU, MD

from Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing

University Medical School, Nanjing, China

Accuracy and safety of pedicle screw

placement in adult lumbar spine with

and without scoliosis:

a case-control study

QF # 73

Adult lumbar scoliosis

Pedicle screw based constructs

Advantage: Stabilize three columns of

the spine

# 4787, M 49ys

For scoliosis,

pedicle screw placement involves

increased risk of perforation

Aorta

#10019，F, 23 y, Congenital

Anterior perforations

at L2, L4 and L5.

A systemic review of all prospective studies

until 2010

Accuracy (%of the screws fully

contained in pedicles)

69 to 94%, free-hand

28 to 85%, fluoroscopy,

81 to 92%, fluoroscopy-

navigation

89 to 100% with CT navigation

Gelalis ID, et al. Eur Spin J , 2012

Accurately

placed

Lateral

perforated

Medial

perforated

Anterior

perforated

Endplate

perforated

Currently available data in terms of pedicle screw accuracy in

adults with or without lumbar scoliosis were from multiple centers,

with varied techniques and experiences.

The purpose was to compare the accuracy

and safety of lumbar pedicle screw placement

by one team in scoliosis adults versus non-

scoliosis adults,

and to shed light on the malpositioning pattern

of pedicle screws as well as the possible risk

factors of screw misplacement.

Purpose

Patients and Methods

Scoliosis Non-scoliosis

N=65 (M/F, 17/48) N=127 (M/F, 68/59)

Age : 30-68 yr Age : 31-69 yr

Lumbar idiopathic

scoliosis, degenerative

scoliosis

Degenerative lumbar

stenosis, and Grade I

degenerative

spondylolisthesis

Placement: Using free-hand technique

Post-Op CT: To assess screw positions #5629 F, 59y

#8352 F, 46y

Classification of screw positions

Safety： Medial breach ≤ 2

mm, breach ≤ 4 mm of

lateral or anterior wall

without aorta impingement.

Potential risk: Medial

breach ≥ 2 mm, breach ≥ 4

mm of lateral or anterior

wall , or with aorta

impingement

Modi NH, et al. Euro Spine J, 2008;

Upendra BN, et al. Spine, 2008;

Gertzbein SD, et al. Spine ,1990,

Grade Screw position

0 Fully contained within

the cortex

1 Cortical breach ≤ 2mm

2 Cortical breach of

2 to 4mm

3 Cortical breach of

4 to 6mm

4 Cortical breach ≥ 6mm

Accuracy: w/o cortical

breach (Grade 0)

Group Scoliosis Non-

scoliosis Stat.

No. of Pts 65 127

Average age 39 yr 45 yr P > 0.05

Screws 457 546

Accuracy of screws 89.5% 91.9% Chi-sq = 0.086,

P = 0.769

Rate of screw penetration 48 (10.5%) 44 (8.1%) Chi-sq = 1.482,

P = 0.223

Complications:

Dural tear occurred in 5 patients.

NO vascular injury. No neurological deficits.

Results

Distribution of screw

positions in both groups

At potential risk

Safely placedAccurately placed

0

100

200

300

400

500

600

8 4

48 44

409 502

0%

50%

100%

0%

50%

100%

0%

50%

100%

Accurately

Penetrated

Misplacement pattern in

Scoliosis pts

#8212，F, 43y，Adult IS

Screw at concave

side of L5

penetrated 6.6mm

(Grade 3)

High accuracy and safety of pedicle screw placement

can be achieved in adult lumbar scoliosis,

comparable to those without scoliosis.

Surgeons should carefully determine the length and

direction of pedicle screw during placement in severe

scoliosis, in the apical region as well as on the

concave side.

Conclusion

Disclosures

Xu SUN

Lei-Lei XU

Feng ZHU

Qi DING

Zezhang ZHU

Bin WANG

Bang-ping QIAN

Yang YU

Yong QIU

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