Quantitative Analysis Of Muscle, Baseline Radiographic Evaluation And Post-operative Outcome Analysis In Patients With Spinal Deformity

Chapter 2 (Section 1) Spino-femoral muscles affect sagittal alignment and compensatory recruitment:a new look into soft tissues in adult spinal deformityIntroduction:The muscular system plays an essential role in the maintenance of postural alignment. Previous work linked spinal muscle degeneration to the loss of lumbar lordosis, but was limited to cross-sectional muscle area. However, few studies studied the impact of volume and fat infiltration of the spinal and hip muscles. This study investigated the contribution of muscle degeneration to sagittal malalignment and the recruitment of compensatory mechanisms.Methods:Female ASD patients, aged 35-80y with no history of spinal surgery or hip/knee instrumentation, were enrolled. Correlations were performed between classic spinopelvic radiographic parameters, muscle parameters, and SRS-22 scores. T1-weighted Turbo Spin Echo sequence MRIs with a previously validated Dixon method from the proximal tibia up to T12 vertebra was performed in addition to 36 inch standing radiographs. Using the Deformation of Parametric Specific Objects (DPSO) method,3D reconstructions of 17 muscles, including extensors and flexors of spine, hip, and knee, were obtained. Standardized muscle volume and the percentage of fat infiltration (Pfat, a marker for muscle degeneration) were calculated. A lower muscle volume and higher Pfat indicated greater muscle degeneration. Health-related quality of life was evaluated with SRS-22 instrument.Results:22 ASD patients (mean 61 yo) were included. Significant correlations were observed between sagittal alignment and the muscle parameters. C7-S1 SVA correlated with greater fat infiltration of the hip and knee flexors (r=0.44,0.55, respectively) and extensors (r=0.49,0.55, respectively), all p<0.05. Greater PT correlated with smaller volumes of the spinal flexors and extensors (r=-0.53,-0.51, p<0.02, respectively), hip and knee extensors (r=-0.47,-0.43, p<0.05, respectively). Smaller volume of the spine and hip extensors correlated with larger PT/PI (recruitment of pelvic compensation) (r=-0.62,-0.43, p<0.05, respectively). SRS-22 image domain significantly correlated with the volume of Spine/volume of leg (r=0.52).Conclusions:Using novel MRI 3D reconstruction techniques, this pilot study is the first to quantify the relationship between degeneration of the spinal flexors/extensors and hip extensors and sagittal malalignment. Muscle degeneration significantly limits pelvic compensation for spinal malalignment. Future surgical planning algorithms should incorporate patient-specific soft tissue profiles.Chapter 3 (Section 1) Vertebral rotatory subluxation in degenerative scoliosis:the facet joint tropism is RelatedIntroduction:Vertebral rotatory subluxation (VRS) has been considered as one of the prognostic factors for degenerative scoliosis. Even though several risk factors of VRS including age, Cobb angle have been investigated, few studies exist that evaluate the correlation between VRS and anatomical structures of vertebral column. The aim of this study is to identify facet tropism as one of the possible risk factors leading to vertebral rotatory subluxation.Methods:This retrospective study recruited 23 patients diagnosed as degenerative lumbar scoliosis with VRS. The lateral translation on coronal radiographs was measured and 5mm was used as the cut-off value of defining rotatory subluxation. Computer tomography (CT) scans for facet joints were made for all lumbar levels. Difference between right and left facet angles was recorded as delta FA (ΔFA). Facet tropism was defined as the difference between the bilateral FA more than 10°.Results:In the present study, VRS was found most commonly at L3/41evel (49%), and in decreasing frequency at L2/L3 (24%), L4/L5 (20%), and L1/L2 (7%). On the convex side of the main curve, face joints at levels with VRS were more coronally oriented compared to those at levels without VRS (41.64°±11.65 vs.36.30°±10.99, p=0.034). ΔFA was also significantly different between levels with and without VRS (p=0.005). Strong correlation was found between ΔFA and lateral translation with a coefficient of 0.33 (p<0.001). In addition, logistic regression was also performed and ΔFA was the only parameter included into equation (p=0.001).Conclusions:Facet tropism was more significantly observed at levels with VRS. Coronally facet orientation on the convex side and severe facet tropism in degenerative scoliosis should be considered as possible risk factors for VRS.Chapter 3 (Section 2) Abnormal growth of spine in patients with adolescent idiopathic thoracic scoliosisObjective:To investigate if the growth patterns of the spine and pelvis are consistent in adolescent idiopathic scoliosis (AIS) patients with single thoracic curves.Methods:48 T-AIS patients and 48 healthy age-matched adolescents were recruited consecutively. Radiographic parameters including height of spine (HOS), length of spine (LOS), height of thoracic spine (HOT), length of thoracic spine (LOT), height of pelvis (HOP), width of pelvis (WOP) and width of thorax (WOT) were measured on the long-cassete posteroanterior standing radiographs. In addition, ratios including HOS/HOP, LOS/HOP, HOT/HOP, LOT/HOP, LOT/LOS, WOT/WOP were also calculated.Results:Compared to the age-matched healthy adolescents, T-AIS patients had a significantly higher LOS and LOT. Yet, the height and width of the pelvis and the width of thorax showed no significant difference between thoracic AIS patients and healthy adolescents. Similarly, LOS/HOP and LOT/HOP were significantly higher in T-AIS patients as may be expected.Conclusion:Compared to the age-matched healthy adolescents, T-AIS patients had an abnormal growth characteristics with longer spine. The growth of pelvis and thorax showed no significant differences between T-AIS patients and healthy adolescents.Chapter 3 (Section 3) The influence of supine position on lumbar lordosis in adolescent idiopathic scoliosis with or without lumbar curveObjective:To quantify the influence of supine position to lumbar lordosis and to evaluate whether lumbar curve would affect the change of lumbar lordosis from standing position to supine position.Methods:Fifty female thoracic adolescent idiopathic scoliosis (T-AIS) patients and forty-four female lumbar adolescent idiopathic scoliosis (L-AIS) patients were retrospectively reviewed in this study. Patients with history of brace treatment neuromuscular disease, osteopenia, neurological disorders, endocrine disorders, connective tissue diseases or abnormal intelligence were excluded. The long-cassette standing radiographies and lumbar X-ray films in supine position were obtained from all subjects. Lumbar lordosis (LL) was measured on both standing and supine films. The relationship between standing LL and supine LL was calculated by Pearson correlation in both T-AIS and L-AIS groups. The differences in terms of standing LL, supine LL and ALL were also analyzed through independent t test. Statistically significant differences were defined by P<0.05.Results:The mean age of T-AIS patients was 14.95±2.8 years and the Cobb angle averaged 47.2°±10.4. While in L-AIS patients, the age averaged 15.22±2.3 years and Cobb angle 48.1°±9.3. No difference was found in terms of age and Cobb angle (P>0.05). The standing LL averaged 50.49° in T-AIS group, which was significantly larger than supine LL in the same group (50.49° vs.40.79°, P<0.05). Similarly, significant difference was also observed in L-AIS group (51.95° vs.37.37°, P<0.05). According to Pearson correlation, strong correlations were observed between standing LL and supine LL in both T-AIS and L-AIS groups. The regression formula of standing LL in T-AIS group was Standing LL=25.913+0.602×Supine LL; while the formula in L-AIS group was Standing LL=19.779+0.888×Supine LL.Conclusion:In both T-AIS and L-AIS groups, strong correlations could be found between standing LL and supine LL. The change of LL was more obvious in L-AIS patients. The difference between standing and supine LL should be considered in surgery of L-AIS patients.Chapter 4 (Section 1) Pre-operative digitalized simulation of osteotomy in degenerative kyphoscoliosis:An effective method for surgical planningObjective:To assess the availability of applying pre-operative digitalized simulation of osteotomy in degenerative scoliosis by comparing the sagittal parameters of pre-operative simulation and post-operative results.Methods:This is a retrospective study of 16 degenerative scoliosis patients who underwent posterior PSO surgeries in our center from June 2012 to June 2014, including 3 males and 13 females. Long-cassette standing upright posterior-anterior and lateral radiographs of the spine and pelvis were taken before and two weeks after surgery. The sagittal radiographic parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), and sagittal vertical axis (SVA) were measured. PT setting method and ratio control method were used in pre-operative lateral radiographs for digital design of osteotomy, and the sagittal parameters were measured after osteotomy simulation. Pared-samples t test was conducted to assess difference in terms of sagittal parameters between the 2 methods of osteotomy simulation and post-operative results.Results:Pre-operative digitalized simulation was successfully performed in 15 patients. Satisfactory restoration of LL and SVA was observed in both PT setting method and ratio control method (P>0.05). Smaller PT was found as a result of PT setting method compared to that of post-operative result (11.33±0.47° vs. 20.33±5.37°, P<0.001) while similar PT was simulated by ratio control method.Conclusion:The present study confirmed that the pre-operative digital simulation of osteotomy can predict post-operative sagittal restoration. The combination of PT setting method and ratio control method may be a better solution for simulation. Meanwhile, the angle of osteotomy, the close ratio, and the thoracic kyphosis compensation should be taken into consideration during simulation.Chapter 4 (Section 2) Lumbar lordosis index as a predictor of post-operative sagittal balance during follow-ups in degenerative scoliosisObjective:To evaluate the role that post-operative lumbar lordosis index (LLI) played in predicting the sagittal balance in degenerative scoliosis through comparing the LLI in patients with or without sagittal balance during follow-ups.Methods:This is a retrospective review of 57 patients with degenerative scoliosis who underwent one stage posterior surgical instrumentation in our spinal center from January 2005 to December 2011. The inclusion criteria were as follow:(1) age more than 45 years; (2) with follow-up more than 2 years; (3) with the third generation pedicle screw system; (4) with more than 5 fusion levels; (5) with long-cassettee standing upright sagittal radiographs preoperatively, immediately after operation and at the last follow-up. Patients with osteoporotic fracture, spinal trauma, spinal tumor and with revision surgery during follow-up were excluded. The following sagittal spino-pelvic parameters were measured:sagittal vertical axis (SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). Lumbar lordosis index (LLI) was also assessed with the formula: LLI=LL/PI. Based on sagittal alignment at the last follow-up, patients were divided into two groups:Group A (SVA<5cm and PT<25°) and Group B (SVA>5cm or PT>25°). Independent t test was performed for statistical analysis. For all statistical analysis, the level of significance was set at P< 0.05.Results:The follow-up of the patients averaged 4.4 years (range). Preoperative LLI did not differ significantly between Group A and B (0.45±0.18 vs.0.47±0.21, P=0.638). Post-operative LLI was 0.89±0.13 in Group A, significantly larger than that in Group B (0.89±0.13 vs.0.61±0.14, P=0.005).SVA in Group A was 2.73±2.62cm at the last follow-up, significantly smaller than that in Group B (2.73±2.62cm vs. 7.81±3.26cm, P<0.01). PT at the last follow-up averaged 20.34±4.28° and 29.81±5.13° respectively in Group A and B. In addition, post-operative LLI was significantly correlated to SVA at the last follow-up (r=-0.248, P<0.05).Conclusion:Post-operative LLI could be used as a predictor of the prognosis of sagittal balance. Well-restored LLI may reduce the risk for post-operative sagittal imbalance during follow-ups.