Clinical effect of preoperative orthopedic design by Surgimap Spine in the treatment of thoracolumbar kyphosis in ankylosing spondylitis

English Keywords:Ankylosing spondylitis  Thoracolumbar kyphosis  Osteotomy and othopedic design  Surgimap Spine  Curative effect

English Abstract:

  【Abstract】 Objectives: To analyze the clinical effect of preoperative osteotomy and orthopedic design by using Surgimap Spine software in the treatment of thoracolumbar kyphosis in ankylosing spondylitis(AS). Methods: The patients who underwent osteotomy and orthopedic correction for AS thoracolumbar kyphosis at the Department of Spine and Spinal Cord Surgery, Henan Provincial People′s Hospital, from January 2019 to April 2021, were retrospectively analyzed, which included 15 males and 1 female, aged 19-46 years(32.7±8.1 years). Before operation, a full-length spine lateral radiograph was imported to the Surgimap software, and sagittal parameters such as pelvic parameters, chin-brow vertical angle(CBVA), and sagittal vertical axis(SVA) were measured; the pelvic tilt(PT) angle was revolved to ideal values; the line between the center of the C7 vertebra and the posterosuperior corner of S1 was connected, the center of C7 was rotated to just above the sacrum along the center of the cortex in front of the proposed osteotomy vertebra, and the angle of rotation α was calculated as the angle of osteotomy in prediction of SVA=0mm; The angle(β) at SVA=50mm was simulated using osteotomy tool. The osteotomy tool was then applied to simulate the angles(γ, δ) needed at CBVA=10° and 20°, respectively. Patients with cervical ankylosis δ≤osteotomy angle λ≤γ and β ≤osteotomy angle λ≤α; Patients without ankylosis of the cervical spine, β≤osteotomy angle λ≤α. Intraoperative osteotomies were guided according to the set range of osteotomy angles. Anteroposterior and lateral radiographs of the entire spine were performed preoperatively, 2 weeks postoperatively, and at final follow-up, and CBVA, global kyphosis(GK), thoracic kyphosis(TK), thoracolumbar kyphosis(TLK), lumbar lordosis (LL), PT, pelvic incidence(PI), sacral slope(SS), the value of PI-LL, SVA and other parameters were measured and compared. Scoliosis Research Society-22(SRS-22) questionnaire score and Oswestry disability index(ODI) were used to evaluate the clinical efficacy, and the surgical related complications were recorded. Results: The procedures were uneventful in all patients, and 5 patients were combined with cervical ankylosis, 3 of whom could not meet both SVA and CBVA needs, which were weighed according to the surgeon′s experience. The operative time was 350-490min(420±38.9min) and intraoperative blood loss was 900-1900ml(1366.5±337.3ml). Postoperative follow-up ranged from 6 to 24 months with a mean of 12.6±5.6 months. Before surgery, 2 weeks after surgery, and at final follow-up, CBVA was 33.1°±13.1°, 8.2°±3.8°, and 10.5°±4.2°; GK was 68.5°± 28.4°, 35.4°±12.0°, and 36.1°±10.6°; TK was 51.3°±17.3°, 35.9°±9.9°, 35.7°±8.7°; TLK was 31.5°±16.1°, 15.2°±7.4°, 14.5°±7.2°; LL was -2.3°±20.8°， -39.7°±12.9°, and -37.8°±8.9°, respectively; PT was 36.5°±11.5°, 23.2°±9.1°, and 25.4°±7.9°; SS was 13.2°±8.8°, 25.2°±8.5°, and 26.2°±8.7°; PI-LL was 37.3°±15.6°, 8.3°±8.7°, and 10.5°±9.5°; SVA was 175.3±47.4mm, 38.2±10.2mm, and 44.2±11.3mm, respectively. Significant improvements of the above parameters were observed at 2 weeks postoperatively and at final follow-up compared with those before surgery(P<0.05). The PI was 48.2°±13.3°, 48.0°±12.7°, and 48.1°±12.3° preoperatively, 2 weeks postoperatively, and at final follow-up, respectively, with no significant changes(P<0.05). Both ODI and SRS-22 at final follow-up were significantly improved compared with their preoperative values(P<0.05). The horizontal gaze and living ability were improved significantly after the operation, and no internal fixation loosening, displacement or fracture were observed at final follow-up, and the bone graft fusion was sufficient.　Conclusions: It is feasible to apply digital intelligent software-Surgimap Spine to assist designing osteotomy before operation for the treatment of thoracolumbar kyphosis in AS, and the clinical outcomes can be satisfactory.