Impact of Sagittal Balance on Clinical Outcomes in Surgically Treated T12 and L1 Burst Fractures: Analysis of Long-Term Outcomes after Posterior-Only and Combined Posteroanterior Treatment

Abstract

Objective. Long-term radiological and clinical outcome retrospective study of surgical treatment for T12 and L1 burst fractures in perspective of sagittal balance measures. Methods. Patients with age of 16-60 years, complete radiographs, early surgical treatment surgery, and follow-up (F/U) > 18 months were included and strict exclusion criteria applied. Regional and thoracolumbar kyphosis angles (RKA and TLA) were measured preoperatively and at final F/U, as were parameters of the spinopelvic sagittal alignment. Clinical outcomes were assessed using validated measures. Results. 36 patients with age mean age of 39 years and F/U of 69 months were included. 61% of patients were treated with bisegmental posterior instrumentation (POST-I) and 39% with combined posteroanterior instrumented fusion (PA-F). At F/U, several indicators for clinical outcomes showed a significant correlation with radiographic measures in the overall cohort with inferior clinical outcomes corresponding with increasing residual deformity and sagittal malalignment. Statistical analysis failed to reach level of significance for the differences between POST-I and PA-F group at final F/U. Only a strong trend towards better restoration of the thoracolumbar alignment was observed for the PA-F group in terms of the RKA and TLA. Conclusions. Results in a surgically treated cohort of T12 and L1 burst fracture patients indicate that superior clinical outcomes depend on restoration of sagittal alignment.

Figure 1

Illustrative case 1. A 62-year-old female patient with a T12 burst fracture after a fall while cross-country skiing (a, b). The fracture was classified as AO 3.2.1 and LSC 5 (c, d). Surgical treatment was performed using closed reduction and posterior instrumentation at T11–L1. The preoperative RKA and TLA were 5.1° and 11.2°, respectively, and the RKA and TLA at the final follow-up of 76 months postoperatively were 11.3° and 14°, respectively (e, f).

Figure 2

Illustrative case 2. A 51-year-old male patient suffered a L1 fracture during a motor vehicle accident (a, b). The AO Classification was 3.3.1, and the LSC was 9 (c, d). After primary closed reduction and posterior instrumentation at T12–L2 (e), staged anterior surgery using instrumented fusion was conducted after 6 days with partial corpectomy and implantation of a distractible vertebral body replacement. The preoperative RKA and TLA were 20.3° and 9.7°, respectively, and the RKA and TLA at the final follow-up of 33 months postoperatively were 1.4° and 2.2°, respectively (g, h). In the CT scan at the final follow-up, the anterior column was considered fused (f).

Figure 3

The RKA (regional kyphosis angle) is measured between the tangent of the upper endplate of the cephalad vertebra of the fracture and the tangent of the lower endplate of the caudal vertebra.

Figure 4

Illustration of the assessed radiographic spinal outcome parameters. RKA: regional kyphosis angle; TLA (T10–L2): thoracolumbar junction angle T10–L2; PI: pelvic incidence; PT: pelvic tilt; SS: sacral slope; TLSL T12–S1: thoracolumbosacral lordosis T12–S1; LSL L1–S1: lumbosacral lordosis L1–S1; LL L1–L5: lumbar lordosis L1–L5; TK T4–T12: thoracic kyphosis T4–T12; PR-S1: pelvic radius to S1; PR-T10: total lumbopelvic lordosis to T10; PR-L2: regional lumbopelvic lordosis to L2; SVA T4–S1: sagittal vertical axis T4 to S1.