Effects of different pelvic incidence minus lumbar lordosis mismatch after long posterior instrumentation and fusion for adult degenerative scoliosis

Abstract

Objective: To evaluate the influence of PI-LL (pelvic incidence minus lumbar lordosis mismatch) on scoliosis correction, living quality and internal fixation related complications for adult degenerative scoliosis (ASD) after long posterior instrumentation and fusion. Methods: A total of 79 patients with ADS underwent long posterior instrumentation and fusion in the Department of Orthopedics at Beijing Chao Yang Hospital from January 2010 to January 2014 were retrospectively reviewed.There were 21 males and 58 females aging from 55 to 72 years with the mean age (63.4±4.8)years. The patients were divided into three groups according to immediately postoperative PI-LL: PI-LL<10°, 10°≤PI-LL≤20°, PI-LL>20°.Compare the Cobb's angles, PI-LL, Japanese Orthopaedic Association (JOA) score, Oswestry Disability Index (ODI), Visual Analog Scale (VAS) and Lumbar Stiffness Disability Index (LSDI). Measurement data were compared via t test and ANOVA, enumeration data were compared via Kruskal-Wallis test, noncontiguous data was performed by χ(2) test. Univariate linear regression equation was performed to investigate the relative influences of postoperative PI-LL on postoperative radiographic parameters and clinical outcome. Results: All the operations were successful without intraoperative complications. The operation time was 145-310 minutes (235.3±42.0) minutes, the intraoperative blood loss was 300-5 300 ml (1 021±787) ml, the duration of hospital was 12-18 d (14.5±1.3) d. A total of 4 to 10 (7.0±1.1) vertebra levels were fused. Compared to preoperative, the Cobb's angle of scoliosis ((4.2±1.8)° vs. (20.1±2.7)°), PI-LL ((16.1±8.6)° vs. (36.0±4.3)°), JOA (3.0±1.3 vs. 5.5±1.2), ODI (24.4±8.1 vs. 62.9±2.7), VAS (3.0±1.0 vs. 6.8±1.3) were significantly decreased postoperative (t=18.539~53.826, P<0.01). Compared to preoperative, postoperative Cobb's angle of scoliosis ((4.1±2.7)° vs. (19.5±2.7)°, (4.0±1.4)° vs. (20.2±2.4)°, (4.7±0.9)° vs. (20.6±3.0)°) (t=21.148-45.355, P<0.01) and PI-LL ((5.2±2.8)° vs. (35.8±4.9)°, (17.9±2.9)° vs. (37.2±3.9)°, (25.8±2.7)° vs. (34.5±4.0)°) (t=7.227-38.250, P<0.01) were significantly reduced postoperative in PI-LL<10° group, 10°≤PI-LL≤20° group and PI-LL>20° group. Compared to preoperative, ODI (27.7±4.9 vs. 63.3±2.6, 17.7±5.9 vs. 63.1±2.8, 30.6±6.5 vs. 62.3±2.5) (t=21.218~50.858, P<0.01), JOA (2.8±1.2 vs. 5.2±1.2, 3.3±1.1 vs. 5.7±1.1, 2.8±1.7 vs. 5.7±1.2) (t=9.042-16.025, P<0.01) and VAS (2.9±1.2 vs.7.0±1.3, 3.3±0.9 vs.7.0±1.4, 2.9±0.8 vs. 6.3±1.2) (t=16.073-22.214, P<0.01) were all significantly reduced at last follow-up. There were statistic differences in ODI and LSDI (F=38.477, P<0.01; F=37.063, P<0.01) at the last follow-up among the three groups. There was a negative correlation in PI-LL and LSDI according to linear regression (B=-5.838, P<0.01) in the last follow-up. All the patients were followed up, the follow-up duration were 2 to 5 years with the mean (3.1±0.7) years. The internal fixation failure related complications in 3 years included proximal junctional kyphosis (PJK) in 19 cases, internal fixation loosening in 6 cases. Eight patients received reoperation for severe local pain and low extremity symptoms. PJK occurrences were significantly different among PI-LL<10° group, 10°≤PI-LL≤20° group and PI-LL>20° group. Conclusions: The PI-LL between 10° and 20° may be the best choice in ADS patients after long posterior instrumentation and fusion for its better clinical outcome and less proximal junctional kyphosis (PJK). The overcorrection of LL may lead to more serious postoperative lumbar stiffness.