SUMMARY OBJECTIVE; Compare the outcome of spinal deformity correction between Ti-Ti and CrCo-Ti rods for the treatment of spinal Adolescent Idiopathic Scoliosis (AIS) using rods mentioned with all pedicle screws and translation technique. METHOD; 59 patients operated for spinal deformity (Lenke 1 or 2) AIS. The patients were divided into two groups by random allocation using Ti-Ti rods (n = 29) and CrCo-Ti rods (n = 30) and the alone difference among them in the surgical procedure was rod material (Ti-Ti or CrCo-Ti rods) and finally, radiological outcomes were compared preoperatively, postoperatively and at last follow-up for 12 months. RESULTS; Patients’ main curve correction after surgical procedure regardless type of rod was 48.95±11.04 (13-75) degree. Success rate of spinal deformity correction following surgical procedure regardless of type of administered rod was 86.76 ± 11.30 percent (62.5-100%). Mean of deformity correction rate was 91.49±10.67% using CrCo-Ti rods versus 81.86±9.88% using Ti-Ti rods (P-value=0.01). Angle change was 3.29±6.60 for kyphosis angle and 0.59±7.76 for lordosis angle. Rate of main curve correction was not significantly different considering patients’ gender (P-value0.657). Main curve correction success rate was in association with patients’ age and type of rod (P-value=0.054, r=-1.863 and P-value=0.001, r=8.865 respectively). CONCLUSION; CrCo-Ti rods have the ability to produce higher correction rates in AIS compared to Ti-Ti rod of the same diameter. CrCo-Ti rods provide significant and stable spinal correction, especially in correction of main curve. This rate was associated with patients’ age and type of rod administered but not gender.

“Sagittal balance” is defined by the anatomic relationship between the pelvis and the spine in the sagittal plane to keep the center of gravity over the feet. It is important to calculate the anatomical parameters of cervical, thoracic, lumbar, and spinopelvic regions and how any static and dynamic changes could affect the sagittal balance to understand the conditions necessary for such a balance. One of the effective changes in sagittal balance is aging, which leads to changes in spine parameters and further activation of compensatory mechanisms. Understanding the relationships between these parameters, especially in pathological cases, helps correct spine sagittal imbalance.

Background: One of the most important objectives in the deformity correction surgery of spine is to achieve appropriate sagittal alignment, to improve patient outcome and reduce the risk of junctional failure. Intra-operative rod bending is crucial to achieve desired alignment. Objectives: Assessment of accuracy of rod bending by spine surgeons with or with-out template and/or correction. Methods: Spine surgeons were asked to bend two rods; one in-situ on three-dimensional (3D) printed moulage, designed based on schematic representation of a patient with Kyphoscoliosis, the other rod was asked to bend with correction angles. The differences were measured and correlated with experience and specialty. Results: 21 fellowship trained spine surgeons participated in this study, for in-situ rod, mean thoracic and lumbar bend were 65.2 (P = 0.033) and 49.3 (P = 0.077) degrees, respectively and for the correction rod, mean bend in thoracic and lumbar were 53.8 (P = 0.001) and 51.8 (P = 0.004) degrees, respectively, with significant difference from cut-off point. Each curve was over-bend and it was more pronounce in thoracic, both on in-situ and correction rods, 61.9 and 71.1 %, respectively. Level of experience showed positive correlation with degree of rod bending more than five years in thoracic in-situ bend (P = 0.003) and thoracic bend with correction (P = 0.004). Field of specialty showed positive correlation as well; with orthopedic in-situ bend (P = 0.002) and with correction (P = 0.003). Conclusions: Spine surgeons tend to over-bend rods, when given target angles and when correction is needed. However, when provided with template, a 3D printed moulage in our study, accuracy of rod bending improved significantly.

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