ABSTRACT
Objective:To evaluate the prevalence and distribution of ossification of ligamentum flavum (OLF) at the segments adjacent to the apex in patients with degenerative kyphosis.Methods:All of 74 patients with degenerative kyphosis from January 2018 to December 2021 were retrospective reviewed. All patients were taken anteroposterior and lateral radiographs, CT scan and magnetic resonance imaging (MRI) of the entire spine. Global kyphosis, the morphology of kyphosis and the occurrence of OLF at three segments adjacent to the kyphosis apex were recorded.Results:Of the 74 patients, 54 patients (73%) developed OLF in three segments adjacent to the kyphotic apex. The mean age of the 54 patients was 61.4±6.8 years, and the mean global kyphosis was 49.5°±21.2°. Among other 20 patients without OLF, the mean age was 56.1±7.5 years, and the mean kyphosis angle was 52.1°±19.1°. There was a statistically significant difference in ages ( t=2.92, P=0.005), but no statistically significant difference was observed regarding global kyphosis ( t=0.48, P=0.634). In these 74 patients, 9 patients had angular kyphosis, of which 8 (89%) developed OLF; of the 65 patients without angular kyphosis, 46 patients (71%) developed OLF. There was no significant difference between them (χ 2=1.32, P=0.251). Among the 54 patients diagnosed with OLF, 5 patients (9%) suffered ossification of the posterior longitudinal ligament (OPLL) and 20 patients (37%) suffered dural ossification; 43 patients (80%) developed OLF at proximal segments of apex, 6 patient (11%) developed OLF at distal segments of apex, and 5 patients (9%) developed OLF both at proximal and distal segments of apex. Thirty-two patients (59%) developed OLF at the first segment adjacent to the kyphotic apex, 27 patients (50%) developed OLF at the second segment, and 15 patients (28%) developed OLF at the third segment. Conclusion:Among patients with degenerative kyphosis, about 73% may development OLF within three segments adjacent to the kyphotic apex, and it mostly occurred within two segments adjacent to the apex proximally.
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Objective:To evaluate the clinical outcomes and complications of second sacral alar-iliac (S 2AI) technique utilized in degenerative spinal deformity patients, and to analyze the potential risk factors for postoperative sagittal imbalance. Methods:From January 2014 to October 2020, a consecutive cohort of 39 degenerative spinal deformity patients who were treated with S 2AI were retrospectively reviewed, including 4 males and 35 females, aged 63.1±6.7 years (range, 43-73 years). All of the patients had a minimum of 2-year follow-up. According to the sagittal vertical axis (SVA) at the final follow-up, patients were divided into 2 groups. Sagittal balance group (SVA≤50 mm) and sagittal imbalance group (SVA>50 mm). Radiographic parameters including the Cobb's angle, coronal balance distance (CBD), thoracic kyphosis (TK), lumbar lordosis (LL), SVA, pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS) were measured in the standing radiographs before and after operation and at the latest follow up. Comparison was made between the two groups and the differences with statistical significance were analyzed with binary logistic regression analysis. Intraoperative and postoperative complications were recorded. The Scoliosis Research Society-22 (SRS-22) score were employed to evaluate the quality of life. Results:The average follow-up period was 30.3±9.1 months (range, 43-73 months). Eighteen patients (46%) were identified with sagittal imbalance at the last follow-up. Compared with the patients in the sagittal balance group, the preoperative SVA was significantly larger (83.1±56.2 mm vs. 48.1±51.1 mm, t=2.04, P=0.049) and the postoperative TK was significantly greater (27.8°±9.6° vs. 18.9°±13.4°, t=2.36, P=0.024) for patients in the sagittal imbalance group. Scores of pain domain (3.2±0.5 vs. 3.7±0.6) and self-image domain (3.4±0.8 vs. 3.8±0.6) in sagittal imbalance group were significantly lower than those of sagittal balance group ( P<0.05). Logistic regression analysis showed that larger preoperative SVA ( OR=1.02, P=0.028) and greater postoperative TK ( OR=1.09, P=0.022) were independent risk factors for the occurrence of sagittal imbalance during the follow-up periods. Conclusion:S 2AI screw fixation can achieve satisfying coronal deformity correction and great sagittal reconstruction after surgery in patients with degenerative spinal deformity. However, sagittal imbalance may still occur during the follow-up periods. Larger preoperative SVA and greater postoperative TK are independent risk factors for the occurrence of sagittal imbalance.
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Objective:To establish age- and gender-based normative values of sagittal spinal-pelvic alignment in Chinese adult population, and to investigate influence of age, gender and ethnicity on sagittal spinal-pelvic alignment in Chinese normal adults.Methods:A total of 786 asymptomatic Chinese adult volunteers aged between 20 and 89 years were prospectively recruited from different spine centers. The inclusion criteria were: 1) age between 20 to 89 years old; and 2) Oswestry disability index (ODI) scored lower than 20. The exclusion criteria were: 1) previous history of spinal, pelvic or lower limb pathologies that could affect the spine; 2) presence of recent and/or regular back pain; 3) previous surgeries on spine, pelvic and/or lower limb; and 4) pregnancy. Demographic characteristics of these subjects including age, gender, body weight and height were recorded. During the enrollment of volunteers, 16 groups were defined based on the age (20 s, 30 s, 40 s, 50 s, 60 s, 70 s and 80 s) and gender. Whole body biplanar standing EOS X-ray radiographs were acquired to evaluate the sagittal alignment. Spinal-pelvic parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), thoracic kyphosis (T 5-T 12, TK), lumbar lordosis (L 1-S 1, LL), lower lumbar lordosis (L 4-S 1, LLL), global tilt (GT), T1 pelvic angle (TPA) and sagittal vertical axis (SVA) were measured. Values of PI-LL and lordosis distribution index (LLL/LL, LDI) were calculated. Radiographic measurements of 100 subjects were randomly selected to determine the intra- and inter-observer reliabilities using inter- and intra-class correlation coefficients (ICC). The spinal-pelvic parameters were compared among volunteers between different age and gender groups. The comparison was also made among various ethnic population. Results:The mean value was 23.7±7.1 kg/m 2 for BMI and 6.9%±2.5% (range, 0-18%) for ODI score. Each sagittal spinal-pelvic parameter was presented with mean value and standard deviationbased on age and gender. The ICCs of radiographic measurements ranged from 0.89 to 0.95, suggesting good to excellent intra- and inter-observer reliabilities. Significant differences were observed between males and females in multiple sagittal parameters (all P values <0.05). Compared to the male subjects, significantly higher values of PI (41.4° for male vs. 45.0° for female, P<0.001), PT (10.7° for male vs. 13.9° for female, P<0.001), PI-LL (-0.5° for male vs. 1.8° for female, P<0.001), and GT (10.9° for male vs. 13.5° for female, P<0.001) were documented in female subjects. Males had significantly higher values of LLL (28.6° for male vs. 26.6° for female, P<0.001) and LDI (0.68 for male vs. 0.63 for female, P<0.001). PI-LL, SVA, GT and TPA increased with aging from Group 40 s to Group 80 s, while LL, LLL and LDI decreased gradually, and TK decreased slowly with aging. Comparison of sagittal spinal-pelvic parameters between different ethnic subjects showed that Chinese adult population presented lower PI, SS, TK and LL as compared with American population; lower PI, SS and LL as compared with Japanese population. But the variation trend with aging tended to be consistent among different ethnic populations. Conclusion:Age- and gender-based normative values of sagittal spinal-pelvic alignment were established in asymptomatic Chinese adult population. Sagittal spinal-pelvic alignment varies with age and gender, and presented different compensation mechanism among different ethnic populations. Therefore, to achieve balanced sagittal alignment, age, gender and ethnicity should be take intoconsideration when planning spine correction surgery.
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Objective:To investigate the clinical outcomes and complication of posterior surgery for Scheuermann kyphosis fusing to different distal fusion levels.Methods:From January 2012 to December 2017, a consecutive cohort of 34 patients who were treated with posterior spinal instrumented correction and satisfied the inclusion criteria were retrospectively reviewed, including 29 males and 5 females, aged 17.1±4.3 years (range, 12-30 years). All of the patients had a minimum follow-up of 2 years. According to the distal fusion level, patients were divided into 2 groups. Group sagittal stable vertebra (SSV) (22 cases) included patients whose lowest instrumented vertebra (LIV) was SSV; Group SSV-1 (12 cases) included patients who had a LIV one level above the SSV. Radiographic parameters including global kyphosis (GK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were measured in the standing radiographs before and after operation and at the latest follow up. Intraoperative and postoperative complications were recorded. The Scoliosis Research Society-22 questionnaire (SRS-22) were conducted at pre-operation and the final follow up to evaluate the clinical outcomes. The sagittal radiographic parameters and the incidence of distal junctional kyphosis (DJK) were compared between the two groups.Results:There were no significant differences in terms of age, sex, radiographic measurements and scores of SRS-22 between two groups preoperatively ( P>0.05). The correction rates of GK in the SSV group and the SSV-1 group were 42.8%±7.6% and 43.2%±8.4% ( t=0.151, P=0.881) respectively. While the correction rates loss were 1.2%±5.2% and 3.9%±7.2% ( t=0.767, P=0.449) at the latest follow up. No significant difference was observed in terms of other radiographic parameters ( P>0.05). During the postoperative follow up period, 3 patients (16.7%) in SSV group and 2 patients (13.6%) in SSV-1 group developed DJK. The incidence of DJK did not show any significant difference between two groups ( χ2=0.057, P=0.812). At the final follow-up, the function scores of SRS-22 in SSV-1 group (4.1±0.6) was significantly higher than SSV group (3.7±0.5) ( t=2.300, P=0.028) and there was no significant difference in the rest of the domain ( P>0.05). Conclusion:Compared with stopping at SSV, fusion to SSV-1 could achieve comparable curve correction with the preservation of more lumbar motility. Moreover, it would not increase the risk of DJK. As a result, we recommend selecting SSV-1 as the ideal LIV for SK patients.