Radiological analysis of sagittal spino-pelvic alignment in patients with upper lumbar disc herniation

English Keywords:Upper lumbar disc herniation  Pelvic incidence  Lumbar lordosis  Roussouly classification

English Abstract:

  【Abstract】 Objectives: To analyze the sagittal spino-pelvic alignment and its clinical relevance with upper lumbar disc herniation(ULDH). Methods: A total of 29 ULDH patients and 58 normal volunteers from January 2007 to January 2017 were included in this study. Disc herniation was identified in 9 patients at L1/2 level, in 16 patients at L2/3 level， and in 4 patients at both l/2 and L2/3 level. ULDH group contained 29 patients(10 females, 19 males), aged 20-56 years. Control group consisted of 58 volunteers (21 females, 37 males), aged 22-56 years. No differences were found between two groups in terms of age, gender and BMI. Spino-pelvic parameters including pelvic incidence(PI), pelvic tilt(PT), sacral slope(SS), thoracic kyphosis(TK), lumbar lordosis(LL), thoracolumbar junctional angle(TLJ) and sagittal vertical axis(SVA) were obtained. From the standing lateral X-ray films of spine, disc angle, vertebral wedging angle, anterior and posterior disc height, slippage distance were measured. At the same time, distributions of Roussously classification in all patients were determined. Spino-pelvic parameters between two groups were compared via independent t test. Results: The PI, PT, SS and LL in ULDH group were 36.0°±8.8°, 12.5°±6.7°, 23.4°±9.6° and 36.1°±9.1° respectively, which were significantly lower than those in the control group(43.6°±8.6°, 15.4°±6.7°, 28.0°±9.1° and 48.1°±9.0° respectively, P<0.05). However, TK, TLJ and SVA were 33.3°±11.0°, 17.0°±6.6° and 5.6±20.1mm respectively, which were significantly higher than those in the control group(26.7°±12.1°, 6.2°±5.8° and -18.2±16.6mm respectively, P<0.05). In ULDH group, anterior and posterior height of L1/2 disc were 6.1±1.9mm and 5.1±2.1mm respectively, which were significantly lower than those in the control group(9.7±1.8mm and 8.5±2.4mm respectively, P<0.05). Similarly, anterior and posterior height of L2/3 disc were 7.1±2.1mm and 5.1±2.7mm respectively, which were significantly lower than those in the control group(9.5±1.9mm and 8.3±2.6mm respectively, P<0.05). In ULDH group, disc angle at L1/2 and L2/3 was 4.9°±3.0° and 5.2°±2.9° respectively, which was significantly higher than that in the control group(3.2°±2.7° and 3.1°±2.6°, P<0.05). Retrolisthesis was observed in 10 patients(34.5%) in ULDH group, which was significantly higher than that in the control group(0%)(P<0.05). Slippage distance was 5.3±1.9mm in ULDH group. Vertebral wedging was more frequently noted in ULDH group(24/29) than in the control group(2/58)(P<0.05). In ULDH group, the distribution from Roussouly type Ⅰ to Ⅳ was 48.3%, 31.0%, 17.3% and 3.4% respectively; while in control group, it 10.3%, 46.6%, 32.8% and 10.3% respectively. The distribution of type Ⅰ in ULDH group was significantly higher than that in control group(P<0.05), while no significant differences were found in other types between the two groups(P＞0.05). Conclusions: ULDH patients have a distinct spino-pelvic alignment characterized by a low PI and a high distribution of Roussouly type Ⅰ.Besides, the decrease of disc height and increase of disc angle were significant in ULDH patients when compared with the controls.