Level II - Prospective Comparative Study.

No abstract

Level II-diagnostic study-development of a diagnostic criteria on basis of consecutive patients, with gold standard.

Background: Proximal junctional kyphosis (PJK) is a major complication after posterior spinal surgery. It is diagnosed radiographically based on a proximal junctional angle (PJA) and clinically when proximal extension is required. We hypothesized that abnormal spinopelvic alignment will increase the risk of PJK in children with early-onset scoliosis (EOS). Methods: A retrospective study of 135 children with EOS from 2 registries, who were treated with distraction-based implants. Etiologies included 54 congenital, 10 neuromuscular, 37 syndromic, 32 idiopathic, and 2 unknown. A total of 89 rib-based and 46 spine-based surgeries were performed at a mean age of 5.3±2.83 years. On sagittal radiographs, spinopelvic parameters were measured preoperatively and at last follow-up: scoliosis angle (Cobb method, CA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope and PJA. Radiographic PJK was defined as PJA≥10 degrees and PJA≥10 degrees greater than preoperative measurement. The requirement for the proximal extension of the upper instrumented vertebrae was considered a proximal junctional failure (PJF). Analysis of risk factors for the development of PJK and PJF was performed. Results: At final follow-up (mean: 4.5±2.6 y), CA decreased (P<0.005), LL (P=0.029), and PI (P<0.005) increased, whereas PI−LL (pelvic incidence minus lumbar lordosis) did not change (P=0.706). Overall, 38% of children developed radiographic PJK and 18% developed PJF. Preoperative TK>50 degrees was a risk factor for the development of radiographic PJK (relative risk: 1.67, P=0.04). Children with high postoperative CA [hazard ratio (HR): 1.03, P=0.015], postoperative PT≥30 degrees (HR: 2.77, P=0.043), PI−LL>20 degrees (HR: 2.92, P=0.034), as well as greater preoperative to postoperative changes in PT (HR: 1.05, P=0.004), PI (HR: 1.06, P=0.0004) and PI−LL (HR: 1.03, P=0.013) were more likely to develop PJF. Children with rib-based constructs were less likely to develop radiographic PJK compared with children with spine-based distraction constructs (31% vs. 54%, respectively, P=0.038). Conclusions: In EOS patients undergoing growth-friendly surgery for EOS, preoperative TK>50 degrees was associated with increased risk for radiographic PJK. Postoperative PI−LL>20 degrees, PT≥30 degrees, and overcorrection of PT and PI−LL increased risk for PJF. Rib-based distraction construct decreased the risk for radiographic PJK in contrast with the spine-based constructs. Level of Evidence: Level III.

Background: It is unclear whether the type of proximal anchor affects the spine length achieved with distraction-based surgeries in patients with nonidiopathic early-onset scoliosis (EOS). Since distraction may produce kyphosis, spine length should be assessed in the sagittal plane using the sagittal spine length (SSLcurved arc length of the spine in the sagittal plane). Our purpose was to determine if the type of proximal anchor in distractionbased surgeries will affect final spine length. Methods: Patients with nonidiopathic EOS treated with distraction-based systems (minimum 5 y follow-up, 5 lengthenings) were identified from 2 EOS registries. Radiographic analysis preoperative, postimplant (L1), and after each lengthening (L2-L5, L6-L10, L11-L15) was performed with the primary outcome of T1-S1 SSL. Results: We identified 126 patients-70 had rib-based implants (52 congenital, 9 syndromic, 9 neuromuscular) and 56 had spine-based implants (15 congenital, 29 syndromic, 12 neuromuscular) with preoperative age 4.6 years, scoliosis 75 degrees, and kyphosis 48 degrees. After initial correction (P < 0.05), scoliosis remained constant [58 degrees (13 to 104 degrees) at L11-L15] and kyphosis increased over time [38 degrees (9 to 108 degrees) at L1 to 60 degrees (17 to 134 degrees) at L11-L15] (P < 0.05). Preoperative SSL was higher in the spine-based group (29.6 cm) when compared with the rib-based group (25.2 cm) (P < 0.05). This difference was maintained after initial implantation (spine-based: 32.2 cm vs. rib-based: 26.7 cm, P < 0.05) and at final follow-up (spine-based: 37.0 cm vs. rib-based: 34.4 cm, P < 0.05). As preoperative SSL differed between groups, maximum SSL gains per interval were also normalized to preoperative SSL. There was no statistically significant difference between groups at L1, L2-L5, and L6-L10. However, at L11-L15, the rib-based group achieved a more relative increase in spine length compared with the spine-based group (45% vs. 31%, P < 0.05). Conclusion: At minimum 5 year follow-up, distraction-based surgeries increased spine length for patients with nonidiopathic EOS; regardless of proximal anchor type.