The Transverse Process Trajectory Technique: An Alternative for Thoracic Pedicle Screw Implantation-Radiographic and Biomechanical Analysis.

BACKGROUND: This study evaluates the accuracy, biomechanical profile, and learning curve of the transverse process trajectory technique (TPT) compared to the straightforward (SF) and in-out-in (IOI) techniques. SF and IOI have been used for fixation in the thoracic spine. Although widely used, there are associated learning curves and symptomatic pedicular breaches. We have found the transverse process to be a reproducible pathway into the pedicle. METHODS: Three surgeons with varying experience (experienced [E] with 20 years in practice, surgeon [S] with less than 10 years in practice, and senior resident trainee [T] with no experience with TPT) operated on 8 cadavers. In phase 1, each surgeon instrumented 2 cadavers, alternating between TPT and SF from T1 to T12 (n = 48 total levels). In phase 2, the E and T surgeons instrumented 1 cadaver each, alternating between TPT and IOI. Computed tomography scans were analyzed for accuracy of screw placement, defined as the percentage of placements without critical breaches. Axial pullout and derotational force testing were performed. Statistical analyses include paired t test and analysis of variance with Tukey correction. RESULTS: Overall accuracy of screw placement was comparable between techniques (TPT: 92.7%; SF: 97.2%; IOI: 95.8%; P = .4151). Accuracy by technique did not differ for each individual surgeon (E: P = .7733; S: P = .3475; T: P = .4191) or by experience level by technique (TPT: P = .1127; FH: P = .5979; IOI: P = .5935). Pullout strength was comparable between TPT and SF (571 vs 442 N, P = .3164) but was greater for TPT versus IOI (454 vs 215 N, P = .0156). There was a trend toward improved derotational force for TPT versus SF (1.06 vs 0.93 Nm/degrees, P = .0728) but not for TPT versus IOI (1.36 vs 1.16 Nm/degrees, P = .74). Screw placement time was shortest for E and longest for T for TPT and SF and not different for IOI (TPT: P = .0349; SF: P < .0001; IOI: P = .1787) but did not vary by technique. CONCLUSIONS: We describe the TPT, which uses the transverse process as a corridor through the pedicle. TPT is an accurate method of thoracic pedicle screw placement with potential biomechanical advantages and with acceptable learning curve characteristics. CLINICAL RELEVANCE: This study provides the surgeon with a new trajectory for pedicle screw placement that can be used in clinical practice.

Surface topography assessment of body shape after surgical correction in adolescent idiopathic scoliosis.

HYPOTHESIS: Body surface topography (ST) improvements are associated with surgical correction in adolescent idiopathic scoliosis (AIS) and correlate with radiographic imaging. DESIGN: Prospective observational study. INTRODUCTION: Patients undergoing correction of AIS are most affected by body image. Radiographs have been the standard assessment tool but do not assess body shape features. ST, a validated, radiation-free assessment tool, directly represents the patient's deformity. We set out to assess ST improvements associated with surgical correction in AIS. METHODS: Twenty-three consecutive operative AIS patients were enrolled and had radiographs and posterior ST obtained pre- and postoperatively (PO). ST changes were compared using paired t test, and correlations of ST with radiograph measurements were evaluated by linear regression. RESULTS: Mean age at surgery was 15.0 ± 2 years, 82.6% female with mean follow-up of 1.0 year. Major Cobb angle improved from 56.91° ± 15.57° to 13.70° ± 4.89°. ST scoliosis angle corrected from 41.43° ± 11.52° to 11.78° ± 7.84° (p < .0001). Trunk length increased from 401.22 ± 32.43 to 422.30 ± 25.77 mm (Δ21.08 mm; p = .0004). Pelvic obliquity (waist asymmetry) trended toward improvement (6.0 ± 4.3 vs. 5.3 ± 7.1 mm; p = .06). Surface rotation was corrected from 17.35 ± 6.73 to 11.8 ± 4.12 mm (p < .0001), highly correlated with clinical trunk rotation (T p = .002 and TL p = .02). ST highly correlated with radiographic parameters. Sagittal balance correlated with improved function (p = .02). CONCLUSION: ST, a radiation-free body shape assessment tool, improved with surgical correction of AIS and was highly correlated with radiographic outcomes.

Body Image Disturbance Improvement After Operative Correction of Adolescent Idiopathic Scoliosis.

HYPOTHESIS: Body Image Disturbance Questionnaire-Scoliosis version (BIDQ-S) is a sensitive outcomes instrument to evaluate improvements in body image-related psychosocial effects with surgical correction. DESIGN: Prospective observational study. INTRODUCTION: The BIDQ-S was previously validated (convergent validity, internal consistency) as a tool to assess body image-related distress and psychosocial impairment in adolescent idiopathic scoliosis (AIS). This study was conducted to evaluate responsiveness to change in the BIDQ-S associated with surgical treatment of AIS two years postoperatively to complete the validation of this questionnaire. METHODS: Seventy-five consecutive operative AIS patients were enrolled and completed BIDQ-S and Scoliosis Research Society-22 (SRS-22) at preoperative and two-year postoperative visits. Demographic and radiographic data were collected. Preoperative and two-year postoperative BIDQ-S (1 = best, 5 = worst) and SRS-22 scores (1 = worst, 5 = best) were compared using paired t test. Correlations between BIDQ-S and SRS-22 scores were evaluated by linear regression. RESULTS: Eighty-four percent of the subjects were females, with average age at surgery of 14.4 ± 1.6 years. The mean follow-up was 2.26 years (range 2.0-4.5). The major Cobb was corrected from 50.0° ± 7.2° to 14.2° ± 5.8° (Δ = 71.3% ± 12.1%; p < .0001). There was a significant improvement in BIDQ-S scores after surgery (1.64 ± 0.51 to 1.21 ± 0.38, p < .0001). BIDQ-S improvements were correlated with change in SRS self-image (p = .0055), activity (p = .0057), mental (p = .0018), and overall mean (p = .0007) domains. Preoperative, two-year postoperative, and Δ BIDQ-S score were not associated with major Cobb magnitude, truncal rotation, or Lenke curve type. Patients who reached SRS-22r minimal clinically important difference (MCID) in activity and self-image domains had worse preoperative BIDQ scores than those who did not reach MCID (activity 1.91 vs. 1.54 [1 = best, 5 = worst], p = .0099; self-image 2.08 vs. 1.51, p < .0001). Greater improvement in BIDQ-S was noted in patients who reached MCID in SRS-22 self-image than those who did not (Δ = 0.77 vs. 0.38, p = .0052). CONCLUSION: BIDQ-S is responsive to surgical correction of AIS. The BIDQ-S is a valuable clinical outcome tool to assess the psychosocial effects of scoliosis in adolescents augmenting existing outcome instruments.