CoCr rods provide better frontal correction of adolescent idiopathic scoliosis treated by all-pedicle screw fixation.
OBJECTIVE
Pedicle screw fixation is considered biomechanically advantageous in adolescent idiopathic scoliosis (AIS) correction, because it uses as an anchor the pedicle, which is the hardest part of the vertebral body. The ability of the rod to correct and hold the correction is a key factor in the selection of rod material. The goal of this study was to compare the results obtained by stainless steel (SS) and cobalt-chromium (CoCr) rods materials for the treatment of AIS curves.


METHODS
Ninety patients were retrospectively included. Sixty-four patients (group 1) were operated on using CoCr rods. Twenty-six patients (group 2) were operated on using SS rods. All the patients were treated by the same surgeon using all-pedicle screw constructs.


RESULTS
In group 1, the correction was respectively 41.03° and 35.78° for main and secondary curves. In group 2, the correction was respectively 30.98° and 24.42° for main and secondary curves. Statistical analysis showed improved correction rates in patients operated with CoCr rods for main (P < 0.0001) and secondary (P = 0.0003) curves with a lower loss of correction at final follow-up. Regarding the sagittal profile, postoperative T4T12 thoracic kyphosis was 28.04° in CoCr group compared to 22.79° in SS group (P = 0. 0.0038).


CONCLUSIONS
The present study confirms the ability of the all-pedicle screw construct to reach the maximum coronal plane correction and prevent deformity progression while maintaining balance. CoCr rods have the ability to exert higher corrective forces on the spine with relatively small amounts of rod deformation. Our findings confirm that CoCr rods have the ability to produce higher correction rates in frontal plane compared to SS rods of the same diameter.
Department of Pediatric Orthopaedics, Armand Trousseau Hospital, Université Pierre et Marie Curie Paris6, 26 Avenue du Dr Arnold Netter, 75571, Paris Cedex 12, France.
Mayalen
M
Lamerain
Manon
M
Bachy
Marion
M
Delpont
Reda
R
Kabbaj
Pierre
P
Mary
Raphaël
R
Vialle
D000293:Adolescent; D002648:Child; D002858:Chromium Alloys; D005260:Female; D006801:Humans; D008297:Male; D065289:Pedicle Screws; D012189:Retrospective Studies; D012600:Scoliosis / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D013193:Stainless Steel; D013904:Thoracic Vertebrae / Q000601:surgery
D002858:Chromium Alloys; D013193:Stainless Steel