The relationship between lumbar lordosis reconstruction and clinical outcomes in degenerative lumbar scoliosis

English Keywords:Degenerative lumbar scoliosis  Surgical planning  Clinical outcomes  Sagittal imbalance

English Abstract:

  【Abstract】 Objectives: To assess the health-related quality of life after long-segment corrective surgery for degenerative lumbar scoliosis(DLS), and to explore the ideal lumbar lordosis reconstruction. Methods: The study included 55 patients with DLS who underwent long-segment fixation(at least 4 vertebrae), with at least 2 years follow-up. Pre- and post-operative symptoms were assessed by using the visual analog scale(VAS) for low back pain and leg pain; Oswestry disability index(ODI) was used to quantify disability. The sagittal parameters of spine were measured on the anteroposterior and lateral radiographs. Patients were categorized based on whether the postoperative goal of pelvic incidence minus lumbar lordosis(PI-LL) within ± 9° was achieved(group PI-LL+) or not(group PI-LL-). Parameters and clinical outcomes were compared by using independent t-test. Scatter diagrams and fitting curves were used to determine the optimal LL range, an independent t-test was used to compare the symptom scores between patients in(group A) and out(group B) in this range. The difference of ODI between different SVA groups were also analyzed. Results: The 55 DLS patients(40-75, 63.2±6.9 years) showed an average Cobb angle of 25.1°±11.5°(10.2°-52.3°), the preoperative PI was 47.5°±11.2°(23.4°-72.7°). The LL at the final follow-up was lower than the preoperative LL(34.5°±11.9° vs 27.6°±15.2°), while there was no difference between the preoperative SVA and the postoperative value. Group PI-LL+(15 patients) showed worse VAS score for low back pain(4.6±2.5 vs 2.9±2.1, P=0.015) than group PI-LL-(40 patients), while there was no difference in VAS score for leg pain or ODI between the two groups(P>0.05). Scatter diagrams and fitting curves showed that the VAS score for low back pain and the ODI were lower in the PI-LL range of 15°-28°. Patients in group A(19 cases) had better VAS score for low back pain and ODI than group B(36 cases) at the final follow-up(P<0.05), while there was no difference in VAS(leg pain) or ODI (P>0.05). There was no difference in ODI among the 29 patients with SVA<50mm and the 17 patients with 50mm≤SVA<80mm(P>0.05)， and the other 9 patients with SVA≥80mm had higher ODI than patients with 50mm≤SVA<80mm(P<0.01). Conclusions: The goal of LL=PI±9° may be not suitable for Chinese DLS corrective surgery. A surgical plan based on LL=PI-20°(PI-LL=15°-28°) is related to better outcomes. For elderly DLS patients, it is more accurate to use SVA=80mm as the threshold of sagittal imbalance rather than SVA=50mm.