Thoracic pedicle screw instrumentation: the learning curve and evolution in technique in the treatment of adolescent idiopathic scoliosis.
METHODS
Retrospective review.


OBJECTIVE
The purpose of this study is to evaluate the learning curve and associated evolution in surgical technique with thoracic pedicle screw instrumentation in adolescent idiopathic scoliosis (AIS).


BACKGROUND
Common treatment for AIS now includes posterior spinal fusion, using thoracic pedicle screws (TPS). It is critical to assess the efficacy, safety profile, and learning curve associated with this technique as its use becomes more widespread among inexperienced surgeons.


METHODS
Retrospective review of the senior author's first 96 TPS cases for Lenke Type I AIS curves. Multiple regression techniques were used to discern whether increasing case number (CN) was associated with improved perioperative and 2-year minimum radiographic and clinical outcomes. The 96 cases were divided into 4 equal quartiles of 24 cases/group (i.e., Q1-Q4) and compared using analysis of variance measures.


RESULTS
A total of 1169 thoracic pedicle screws were placed in 96 patients. We found a significant correlation between CN and major curve correction at 2 years (P < 0.0001), inverse correlation between CN and length of stay (P = 0.02), and estimated blood loss (P = 0.03), but no differences in cell saver or complications. Univariate analysis revealed significant inverse correlations between increasing CN and transfusion rate (P = 0.02) and operative times (P = 0.0001). Total number of screws placed (Q1:9.4 vs. Q4:16.2, P < 0.0001) and number of screws/level (Q1:0.98 vs. Q4:1.64, P < 0.0001) increased linearly with increasing CN, whereas the average time for screw placement (Q1:24.2 vs. Q4:11.4 minutes, P < 0.0001) and ability to maintain T2-T12 kyphosis decreased (Q1:0.21 vs. Q4:-5.5 P = 0.02) with increasing CN.


CONCLUSIONS
There is a significant learning curve associated with thoracic pedicle screw placement in AIS. We describe several technical steps that can be taken to increase the safety of screw placement at the beginning of the learning curve. Inexperienced surgeons should expect a gradual improvement over time in radiographic and clinical outcomes.
Lonner
Baron S
BS
Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, NY 10021, USA. blonner@nyc.rr.com
Auerbach
Joshua D
JD
Estreicher
Michael B
MB
Kean
Kristin E
KE
D000293:Adolescent; D001863:Bone Screws; D002648:Child; D002983:Clinical Competence; D005260:Female; D006801:Humans; D007858:Learning; D008297:Male; D012189:Retrospective Studies; D012600:Scoliosis / Q000601:surgery*; D013123:Spinal Fusion / Q000193:education / Q000295:instrumentation / Q000379:methods; D013904:Thoracic Vertebrae / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult