[Pathologic features of paraspinal muscle biopsies in patients with adolescent idiopathic scoliosis].

OBJECTIVE: To characterize the paraspinal muscles of adolescent idiopathic scoliosis (AIS) patients, and to further explore its etiology. METHODS: Clinical records and paraspinal muscle biopsies at the apex vertebra region during posterior scoliosis correction surgery of 18 AIS were collected from November 2018 to August 2019. Following standardized processing of fresh muscle tissue biopsy, serial sections with conventional hematoxylin-eosin (HE) and histochemical and immunohistochemical (IHC) with antibody Dystrophin-1 (R-domain), Dystrophin-2 (C-terminal), Dystrophin-3 (N-terminal), Dystrophin-total, Myosin (fast), major histocompatibility complex 1 (MHC-1), CD4, CD8, CD20, and CD68 staining were obtained. Biopsy samples were grouped according to the subjects' median Cobb angle (Cobb angle ≥ 55° as severe AIS group and Cobb angle < 55° as mild AIS group) and Nash-Moe's classification respectively, and the corresponding pathological changes were compared between the groups statistically. RESULTS: Among the 18 AIS patients, 8 were in the severe AIS group (Cobb angle ≥55°) and 10 in the mild AIS group (Cobb angle < 55°). Both severe and mild AIS groups presented various of atrophy and degeneration of paraspinal muscles, varying degrees and staining patterns of immune-expression of Dystrophin-3 loss, especially Dystrophin-2 loss in severe AIS group with significant differences, as well as among the Nash-Moe classification subgroups. Besides, infiltration of CD4+ and CD8+ cells in the paraspinal muscles and tendons was observed in all the patients while CD20+ cells were null. The expression of MHC-1 on myolemma was present in some muscle fibers. CONCLUSION: The histologic of paraspinal muscle biopsy in AIS had similar characteristic changes, the expression of Dystrophin protein was significantly reduced and correlated with the severity of scoliosis, suggesting that Dystrophin protein dysfunctions might contribute to the development of scoliosis. Meanwhile, the inflammatory changes of AIS were mainly manifested by T cell infiltration, and there seemed to be a certain correlation between inflammatory cell infiltration, MHC-1 expression and abnormal expression of Dystrophin. Further research along the lines of this result may open up new ideas for the diagnosis of scoliosis and the treatment of paraspinal myopathy.

Dropped head syndrome: a treatment strategy and surgical intervention.

PURPOSE: The pathology of dropped head syndrome (DHS) is diverse, and reports of surgery for DHS are scarce. We aimed to describe surgery for DHS and to investigate the surgical outcomes thereof. METHODS: We enrolled 40 consecutive patients (six males and 34 females; average age at surgery, 72.0 years) with DHS who underwent correction surgeries at a single institute. Short fusion (SF), with the extent of fixation mainly at the cervical region, was performed for 27 patients; long fusion (LF), involving the cervical and thoracic spine, for 13. Clinical and radiological outcomes were investigated, and factors analyzed using the Japanese Orthopedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ). RESULTS: All patients were able to gaze horizontally at the follow-up. Instances of five transient C5 palsy results, and five distal junctional kyphosis results were found, but no revisions were reported due to recurrence. Patients whose T1 slope-20° was smaller than the C2-7 angle postoperatively exhibited better clinical outcomes in the three domains of the JOACMEQ, regardless of the extent of fixation. CONCLUSION: For cases where the T1 slope is relatively small, and approximately 10° of cervical lordosis is predicted to be obtained postoperatively, SF is appropriate. Alternatively, for cases with higher T1 slope, obtaining a cervical lordosis over 20° has a risk of postoperative complications. For such cases, it is an option to perform an LF involving the cervical and thoracic spine.

Preoperative Association Between Quantitative Lumbar Muscle Parameters and Spinal Sagittal Alignment in Lumbar Fusion Patients.

STUDY DESIGN: A retrospective cross-sectional study. OBJECTIVE: To assess the association between spinal muscle morphology and spinopelvic parameters in lumbar fusion patients, with a special emphasis on lumbar lordosis (LL). SUMMARY OF BACKGROUND DATA: Maintenance of sagittal alignment relies on muscle forces, but the basic association between spinal muscles and spinopelvic parameters is poorly understood. MATERIALS AND METHODS: Patients operated between 2014 and 2017 who had both lumbar magnetic resonance imaging scan and standing whole-spine radiographs within six months before surgery were included. Muscle measurements were conducted on axial T2-weighted magnetic resonance images at the superior endplate L3-L5 for the psoas and L3-S1 for combined multifidus and erector spinae (paraspinal) muscles. A pixel intensity threshold method was used to calculate the total cross-sectional area (TCSA) and the functional cross-sectional area (FCSA). Spinopelvic parameters were measured on lateral standing whole-spine radiographs and included LL, pelvic incidence (PI), PI-LL mismatch, pelvic tilt, sacral slope, thoracic kyphosis, and sagittal vertical axis. Analyses were stratified by biological sex. Multivariable linear regression analyses with adjustments for age and body mass index (BMI) were performed. RESULTS: A total of 104 patients (62.5% female) were included in the analysis. The patient population was 90.4% White with a median age at surgery of 69 years and a median BMI of 27.8 kg/m 2 . All muscle measurements were significantly smaller in women. PI, pelvic tilt, and thoracic kyphosis were significantly greater in women. PI-LL mismatch was 6.1° (10.6°) in men and 10.2° (13.5°) in women ( P =0.106), and sagittal vertical axis was 45.3 (40.8) mm in men and 35.7 (40.8) mm in women ( P =0.251). After adjusting for age and BMI, paraspinal TCSA at L3-L5, and paraspinal FCSA at L4 showed significant positive associations with LL in women. In men, psoas TCSA at L5 and psoas FCSA at L5 showed significant negative associations with LL, but none of the paraspinal muscle measurements. CONCLUSION: Our findings indicate that psoas and lumbar spine extensor muscles interact differently on LL among men and women, creating a unique mechanical environment. LEVEL OF EVIDENCE: Level 4.

Cardiorespiratory function of patients undergoing surgical correction of Scheuermann's hyperkyphosis.

The aim of this study was to analyze the impact of surgical correction of the thoracic deformity on the cardiorespiratory function of patients with moderate-severe Scheuermann's hyperkyphosis (SK). A series of 23 adolescents with SK who underwent surgery through an only posterior approach using all pedicle screw constructs were included in the study. Cardiorespiratory parameters were measured during a maximal exercise tolerance test before and 2 years after surgery. Heart rate, oxygen saturation (SatO2), maximum oxygen uptake (VO2 max), ventilatory capacity at maximal exercise (VEmax), and energy costs were recorded. There were statistically significant differences in the forced vital capacity (FVC) (P < 0.05), total VO2max (ml/min) (P < 0.01), maximum expired volume (VEmax) per minute (P < 0.01) and cardiovascular efficiency (HR/VO2 ratio) (P < 0.05). None of these changes were clinically relevant. There were no changes in the VO2max per kg of body mass. The magnitude of the kyphosis correction did not correlate with the change in normalized VO2max or VEmax. In conclusion, patients with moderate-severe SK improve their baseline respiratory limitations and the tolerance to maximum exercise 2 years after surgery. However, the slight cardiorespiratory functional improvements should not necessarily be attributed to the surgery, and could also be caused solely by the residual growth of the lungs and thorax. Furthermore, respiratory functional changes are under thresholds considered as clinically relevant.

Transiency of postoperative cervical kyphosis seen after surgical correction of sagittal malalignment in adult spinal deformity patients.

OBJECTIVE: In this study, we evaluated factors affecting changes in cervical lordosis after deformity correction and during follow-up period in adult spinal deformity (ASD) patients with severe sagittal imbalance. METHODS: Seventy-nine patients, with an average age of 71.6 years, who underwent long-segment fixation from T10 to S1 with sacropelvic fixation were included. We performed a comparative analysis of the radiographic parameters after surgery (Post) and at the last follow-up (Last). We calculated the Pearson's correlation coefficient and performed multilinear regression analysis to predict independent parameters for Post and Last cervical lordosis (CL), T1 slope (T1S), and thoracic kyphosis (TK). RESULTS: Hyperlordotic changes of -23.3° in CL before surgery was reduced to -7° after surgery, and Last CL had increased to -15.3°. T1S was reduced from 27° before surgery to 14.4° after surgery and had increased to 18.8° at the last follow-up. Through multilinear regression analysis, we found that Post CL and T1S were more significantly affected by the amount of LL correction (p = .045 and .049). The effect of Last T1S was significantly associated with the Last CL; the effect of Last TK, with the Last T1S; and the effect of Post PI-LL, with the Last TK (p < .05). CONCLUSION: The postoperative kyphotic change in CL in ASD patients with preoperative cervical hyperlordosis is not permanent and is affected by drastic LL correction and SVA restoration. To achieve spinopelvic harmony proportional to the difference in LL relative to PI, TK becomes modified over time to increase T1S and CL, in an effort to achieve optimal spine curvature.

Different Types of Double-Level Degenerative Lumber Spondylolisthesis: What Is Different in the Sagittal Plane?

BACKGROUND: Degenerative lumber spondylolisthesis (DLS) is a common orthopedic condition, described as a condition that compared with the lower vertebra, the superior vertebra slides forward or backward in the sagittal plane without accompanying isthmic spondylolisthesis. Information pertaining to different types of double-level DLS is scarce. This study aims to analyze parameters of patients with different types of double-level DLS to provide a reference for guiding surgical treatment and restoring sagittal balance of patients with DLS. METHODS: From January 2014 to January 2020, records of patients with double-level DLS were retrospectively reviewed. Patients with double-level DLS were divided into 3 types: anterior, posterior, and combined; the anterior and combined types were studied. The sagittal spinopelvic parameters included C7 tilt, maximal thoracic kyphosis, maximal lumbar lordosis (LLmax), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). After descriptive analysis, demographic and radiographic data were compared. RESULTS: Forty and 18 patients were included in the anterior and combined type groups, respectively. Both groups had different levels of chronic low back pain, but the incidence of radiating leg pain and neurogenic claudication was significantly higher in the anterior type. Oswestry Disability Index and visual analog scale low back scores were also higher in the anterior type. In the anterior type, C7 tilt (7.14 ± 2.15 vs. 5.41 ± 2.28, P = 0.007), LLmax (50.02 ± 14.76 vs. 36.96 ± 14.56, P = 0.003), PI (68.28 ± 9.16 vs. 55.53 ± 14.19, P < 0.001), PT (28.68 ± 7.31 vs. 19.38 ± 4.70, P < 0.001), and PT/PI (42.45 ± 11.22 vs. 36.04 ± 9.87, P = 0.041) were significantly higher. In the anterior type, PI correlated positively with LLmax (r = 0.59) and SS (r = 0.71). LLmax and SS (r = 0.65) had a positive correlation. PT/PI and SS (r = -0.77) had a negative correlation. In the combined type, PI correlated positively with LLmax (r = 0.61) and SS (r = 0.88), and PT/PI correlated negatively with SS (r = -0.81). CONCLUSIONS: In patients with double-level DLS, the sagittal spinopelvic parameters differed between the anterior and combined types. Overall, spinal surgeons should focus on correcting sagittal deformities, relieving postoperative clinical symptoms, and improving quality of life during fusion surgery.

Apoptosis of endplate chondrocytes in cervical kyphosis is associated with chronic forward flexed neck: an in vivo rat bipedal walking model.

BACKGROUND: This study was undertaken to establish a rat bipedal walking model of cervical kyphosis (CK) associated with chronic forward flexed neck and assess the effects of chronic forward flexed neck on endplate chondrocytes. METHODS: Forty-eight 1-month-old Sprague-Dawley rats were randomly divided into 3 groups: forward flexed neck group (n = 16), bipedal group (n = 16), and normal group (n = 16). Cervical curves were analyzed on a lateral cervical spine X-ray using Harrison's posterior tangent method before the experiment and at 2-week intervals for a 6-week period. Histologic changes in cartilaginous endplate chondrocytes were observed using hematoxylin and eosin (H&E) staining, transmission electron microscopy (TEM), and terminal deoxyribonucleotidyl transferase (TdT)-mediated dUTP nick-end labeling. RESULTS: Radiographic findings suggested a significantly decreased cervical physiological curvature in the forward flexed neck group over the 6-week follow-up; normal cervical curves were maintained in other groups. The average cervical curvature (C2-C7) was - 7.6 ± 0.9° in the forward flexed neck group before the experiment, - 3.9 ± 0.8° at 2 weeks post-experiment, 10.7 ± 1.0° at 4 weeks post-experiment, and 20.5 ± 2.1° at the last follow-up post-experiment. Histologically, results of H&E staining unveiled that cartilaginous endplate chondrocytes were arranged in an irregular fashion, with the decreased number at the observation period; the incidence of apoptotic cells in the forward flexed neck group was noticeably higher at the 6-week follow-up than that in other groups. CONCLUSIONS: CK developed as the result of chronic forward flexed neck. Histologic changes suggested that chondrocyte apoptosis may play a critical role in the development of cervical kyphotic deformity associated with chronic forward flexed neck.

The first case report of Kyphoscoliotic Ehlers-Danlos syndrome of chinese origin with a novel PLOD1 gene mutation.

BACKGROUND: Kyphoscoliotic Ehlers-Danlos syndrome (kEDS) is a rare autosomal recessive connective tissue disorder characterized by progressive kyphoscoliosis, congenital muscular hypotonia, marked joint hypermobility, and severe skin hyperextensibility and fragility. Deficiency of lysyl hydroxylase 1 (LH1) due to mutations of PLOD1 (procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1) gene has been identified as the pathogenic cause of kEDS (kEDS-PLOD1). Up to now, kEDS-PLOD1 has not been reported among Chinese population. CASE PRESENTATION: A 17-year-old Chinese male patient presenting with hypotonia, joint hypermobility and scoliosis was referred to our hospital. After birth, he was found to have severe hypotonia leading to delayed motor development. Subsequently, joint hypermobility, kyphoscoliosis and amblyopia were found. Inguinal hernia was found at age 5 years and closed by surgery. At the same time, he presented with hyperextensible and bruisable velvety skin with widened atrophic scarring after minor trauma. Dislocation of elbow joint was noted at age of 6 years. Orthopedic surgery for correction of kyphoscoliosis was performed at age 10 years. His family history was unremarkable. Physical examination revealed elevated blood pressure. Slight facial dysmorphologies including high palate, epicanthal folds, and down-slanting palpebral fissures were found. He also had blue sclerae with normal hearing. X-rays revealed severe degree of scoliosis and osteopenia. The Echocardiography findings were normal. Laboratory examination revealed a slightly elevated bone turnover. Based on the clinical manifestations presented by our patient, kEDS was suspected. Genetic analysis revealed a novel homozygous missense mutation of PLOD1 (c.1697 G > A, p.C566Y), confirming the diagnosis of kEDS-PLOD1. The patient was treated with alfacalcidol and nifedipine. Improved physical strength and normal blood pressure were reported after 12-month follow-up. CONCLUSIONS: This is the first case of kEDS-PLOD1 of Chinese origin. We identified one novel mutation of PLOD1, extending the mutation spectrum of PLOD1. Diagnosis of kEDS-PLOD1 should be considered in patients with congenital hypotonia, progressive kyphoscoliosis, joint hypermobility, and skin hyperextensibility and confirmed by mutation analysis of PLOD1.

Effect of sagittal shape on proximal junctional kyphosis following thoracopelvic corrective fusion for adult spinal deformity: postoperative inflection vertebra cranial to T12 is a significant risk factor.

STUDY DESIGN: This was a retrospective analysis of a prospectively collected consecutive case series of patients with adult spinal deformity (ASD). OBJECTIVE: This study aimed to investigate the impact of the geometrical sagittal shape of the corrected spine on the development of proximal junctional kyphosis (PJK). Several studies have documented risk factors for PJK in ASD surgery. Geometrical assessment is vital for evaluating sagittal spinal deformity. It is essential to assess the postoperative geometrical shape of the spine and the location of the correction in the spine to decrease postoperative junctional stress and PJK. METHODS: Consecutive patients with ASD who underwent corrective fusion with long constructs to the pelvis were included. Patients with neuromuscular disease, congenital and adolescent scoliosis, infection, and spinal tumor were excluded. We investigated the spinopelvic and geometrical parameters of the whole spine. The locations of the thoracic and lumbar apical vertebrae and the inflection vertebrae (IV), where the curvature of the associated adjacent vertebral bodies changes from kyphosis to lordosis, were investigated. The subjects were divided into PJK included patients who underwent revision surgery for junctional failure or with a change in proximal junctional angle ≥ 20°, and non-PJK groups. RESULTS: A total of 139 patients (mean age, 69.6 years; range 18-82 years) were included. There were 47 and 92 patients in the PJK and non-PJK groups, respectively. The IV were located significantly cranial and posterior, the lumbar apex were located significantly posterior in the PJK group at the immediate postoperative time points. The significant risk factors for PJK on binary logistic regression were cranial IV and posterior lumbar apical vertebrae. The incidence of PJK in patients with IV at T12 or cranial tends PJK significantly higher (69%) than at L1 or caudal (26%). CONCLUSIONS: Geometrical spinal shape should be taken into account to reduce the rate of postoperative mechanical complications. LEVEL OF EVIDENCE: Level of evidence III.

Associations between three-dimensional measurements of the spinal deformity and preoperative SRS-22 scores in patients undergoing surgery for major thoracic adolescent idiopathic scoliosis.

STUDY DESIGN: Retrospective study. OBJECTIVE: To analyze the relationships between three-dimensional (3D) measurements of spinal deformity and Scoliosis Research Society-22 (SRS-22) scores in preoperative patients with major thoracic adolescent idiopathic scoliosis (AIS). Previous studies reported 2D measurements were not or only weakly correlated with preoperative SRS-22 scores. However, 2D measures do not always accurately represent the 3D deformity. METHODS: A multicenter prospective registry of surgically treated AIS patients was reviewed for patients with right major thoracic AIS (Lenke type 1-4) who underwent biplanar radiography and completed the SRS-22 questionnaire preoperatively. For the 3D measurements, two reference frames were utilized: global (gravity/patient-based) and local (vertebra/disc-based). To obtain regional measurements, the individual segments in the appropriate reference plane were summed between the levels of interest. Patients were divided into two groups for each SRS-22 domain according to their scores: low (< 4) and high (≥ 4) score groups. Group differences and correlations with SRS-22 scores were analyzed with p < 0.01 as the threshold for significance. RESULTS: There were 405 eligible patients (mean age, 14.4 years). The mean 3D thoracic curve was 59° (45°-115°). The only significant group difference of 3D measurements occurred in the local lumbar lordosis (LL) with a small mean difference (- 3.4°, p = 0.008) in the mental health domain. In the correlation analyses, global and local thoracic kyphosis (TK) and TK/LL ratio demonstrated significant, but weak, correlations with function and total scores (|r|< 0.2, p < 0.01). CONCLUSION: 3D measurements of scoliosis severity have only weak associations with preoperative SRS-22 scores, which might indicate a limit to the discriminative capacity of the SRS-22 within surgical range major thoracic AIS curves. Interestingly, the sagittal plane was the principle 3D plane in which significant correlations existed. LEVEL OF EVIDENCE: II, prognostic.

Long-term impact of sagittal malalignment on hardware after posterior fixation of the thoracolumbar spine: a retrospective study.

BACKGROUND: The importance of sagittal alignment in healthy individuals and in reconstructive spinal surgery has been studied over the last 15 years. The aim of the present study was to assess the long-term effects of abnormal sagittal alignment on hardware after posterior thoracolumbar spinal fusion. METHODS: Patients who had undergone revision surgery (revision cohort, n = 34) due to breakage of their implants were compared retrospectively with patients who had intact implants at the final follow-up investigation after a long posterior thoracolumbar and/or lumbar spinal fusion (control cohort, n = 22). Clinical data and radiological parameters including the sagittal vertical axis (SVA), pelvic incidence (PI), lordosis gap (LG), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), and the femoral obliquity angle (FOA) were assessed on full-spine lateral radiographs obtained in regular standing position. Data were analysed using descriptive statistics, parametric and non-parametric inferential statistics. RESULTS: Patients in the breakage group (female n = 21, male n = 9, mean age 60.9 ± 15.6 years) had a higher anterior shift of the C7 plumb line (SVA) (p = 0.02), retroversion of the pelvis (PT) (p < 0.001), PI-LL mismatch (LG) (p = 0.001), and PI (p = 0.002) than the intact group (female n = 10, male n = 12, mean age 65.7 ± 12.4 years). No significant difference was registered between groups in regard of SS, LL, TK, FOA, and the mean number of comorbidities. CONCLUSION: Failure of restoration of the SVA and the LG to the acceptable ranges, especially in patients with a high PI, may be regarded as a risk factor for the long-term failure of implants after posterior thoracolumbar spinal fusion.

Surgical Treatment for Severe Fixed Hyperkyphosis in an Adult Patient Suffering From Ankylosing Spondylitis and Hereditary Hypophosphatemia With Vertebral Osteopetrosis.

PURPOSE: Ankylosing spondylitis and hereditary hypophosphatemia with long-term high dose supplementation of phosphorous and calcitriol can both lead to severe structural abnormalities of the vertebrae. Impairment of spinal mobility and spinal deformity may ultimately necessitate surgical treatment. A severe fixed hyperkyphosis in a patient with ankylosing spondylitis is a surgically demanding condition, therefore, the indication for surgical treatment should be thoroughly considered and chosen individually. METHODS: This is an uncommon case with a combination of a severe fixed hyperkyphosis with a Cobb-angle of 105 degrees between Th2 and L4 in an adult male patient suffering from ankylosing spondylitis and X-linked hypophosphatemia with surprisingly massive osteopetrosis. In this paper, the coexisting conditions of late-stage ankylosing spondylitis and long-term treated hereditary hypophosphatemia are highlighted. The surgical treatment with different techniques, complications, and results are well explained. RESULTS: A normal gait and stand were achieved by a long posterior fusion with 3 pedicle subtraction osteotomies on L1, L3, and L5. The surgical correction was performed in 3 stages. Postoperative the patient was administered to a rehabilitation center for 3 months. The hyperkyphosis, the C7 plumbline, and the pelvic retroversion were corrected. CONCLUSIONS: Surgical treatment of a severe fixed hyperkyphosis due to ankylosing spondylitis is technically demanding but can be successfully achieved if all surgical challenges and comorbidities are adequately addressed including intraoperative surprising findings like osteopetrotic bone in a patient with hereditary hypophosphatemia as in our case.

Iatrogenic biological fracture of the cervical spine during gradual halo traction for kyphotic deformity correction: case report.

BACKGROUND: Severe kyphotic deformities carry high risk for neurological injuries as osteotomies are often required for correction. Surgeons often utilize a staged approach for dealing with these conditions starting with a period of halo traction to stretch tight soft tissues and partially correct the deformity, followed by surgery. Halo traction is a relatively safe procedure and complications are uncommon. We report a unique case of iatrogenic fracture of the cervical spine during gradual halo traction for deformity correction of a severe cervical kyphosis. CASE PRESENTATION: An 80-year-old female with previous cervical spine tuberculosis infection and C5-C6 anterior spinal fusion developed severe cervical kyphosis of 64° from C2-C6 and neck pain requiring deformity correction surgery. Gradual increase in traction weight was applied, aiming for a maximum traction weight of 45 pounds or half body weight. During the 1st stage halo-gravity traction, sudden neck pain and a loud cracking sound was witnessed during increase of the traction weight to 14 pounds. Imaging revealed a fracture through the C4 and reduction in kyphosis deformity to 11° from C2-C6. There was no neurological deficit. No further traction was applied and the patient underwent an in-situ occipital to T3 fusion without osteotomies. At 3-year follow-up, the patient was symptom-free and radiographs showed solid fusion and maintenance of alignment. CONCLUSIONS: Iatrogenic fracture may occur with halo traction. Elderly patients with osteoporotic and diseased bone should be closely monitored during the treatment. A fracture without complications was a fortunate complication as the patient was able to avoid any high-risk osteotomies for deformity correction. LEVEL OF EVIDENCE: IV.

Effect of decompression range on decompression limit of cervical laminoplasty.

BACKGROUNDS: Cervical posterior decompression surgery is used to relieve ventral compression indirectly by incorporating a backward shift of the spinal cord, and this indirect decompression is bound to be limited. This study aimed to determine the decompression limit of posterior surgery and the effect of the decompression range. METHODS: We retrospectively reviewed the data of 129 patients who underwent cervical open-door laminoplasty through 2008 to 2012 and were grouped as follows: C4-C7 (n = 11), C3-C6 (n = 61), C3-C7 (n = 32), and C2-C7 (n = 25). According to the relative location of spinal levels within a decompression range, the type of decompression at a given level was categorized as external decompression (ED; achieved at the levels located immediately external to the decompression range margin), internal decompression (ID; achieved at the levels located immediately internal to the decompression range margin), and central decompression (CD; achieved at the levels located in the center, far from the decompression range margin). The vertebral-cord distance (VCD) was used to evaluate the decompression limit. The C2-C7 angle and VCD on post-operative magnetic resonance images were analyzed and compared between groups. The relationship between VCD and decompression type was analyzed. Moreover, the relationship between the magnitude of the ventral compressive factor and the probability of post-operative residual compression at each level for different decompression ranges was studied. RESULTS: There was no significant kyphosis in cervical curvature (> -5°), and there was no significant difference among the groups (F = 2.091, P = 0.105). The VCD of a specific level depended on the decompression type of the level and followed this pattern: ED < ID < CD (P < 0.05). The decompression type of a level was sometimes affected by the decompression range. For a given magnitude of the ventral compressive factor, the probability of residual compression was lower for the group with the larger VCD at this level. CONCLUSIONS: Our study suggests that the decompression range affected the decompression limit by changing the decompression type of a particular level. For a given cervical spinal level, the decompression limit significantly varied with decompression type as follows: ED < ID < CD. CD provided maximal decompression limit for a given level. A reasonable range of decompression could be determined based on the relationship between the magnitude of the ventral compressive factor and the decompression limits achieved by different decompression ranges.

A Retrospective Study to Compare the Efficacy of Preoperative Halo-Gravity Traction and Postoperative Halo-Femoral Traction After Posterior Spinal Release in Corrective Surgery for Severe Kyphoscoliosis.

BACKGROUND This retrospective clinical study aimed to compare the efficacy of preoperative halo-gravity traction with postoperative halo-femoral traction after posterior spinal release in corrective surgery for patients with severe kyphoscoliosis. MATERIAL AND METHODS A retrospective clinical study included patients who underwent elective corrective surgery for severe kyphoscoliosis (N=60) between 2013 and 2015. Two patient groups were compared, the postoperative halo-femoral traction after posterior spinal release (R-HF) group (N=30) and the preoperative halo-gravity traction (HGT) group (N=30). Demographic and clinicopathological data included age, gender, Cobb angle, degree of spinal curvature, history of osteotomy, and etiological factors. Patients in the two study groups were matched. Postoperative surgical outcome was evaluated by the radiographic coronal Cobb angle, global kyphosis, coronal balance, and the sagittal vertical axis (SVA). Clinical outcome was assessed using the Scoliosis Research Society Outcomes Questionnaire (SRS-22). RESULTS The preoperative Cobb angle was similar between the R+HF group and the HGT group (123.5±12.7° vs. 123.1±14.1°; P=0.909). Following postoperative traction, a significantly higher correction rate was found in the R+HF group than the HGT group (31.8±7.8% vs. 19.3±12.9%; P=0.001). The postoperative correction rate in the R+HF group was significantly higher than the HGT group (44.7±7.8% vs. 39.0±12.8%; P=0.042). In both study groups, the postoperative SRS-22 scores were significantly improved with no statistical difference between the two groups, and no neurological complications occurred. CONCLUSIONS Patients with severe kyphoscoliosis who underwent postoperative halo-femoral traction after posterior spinal release achieved satisfactory radiographic correction.

The Lumbosacral Takeoff Angle Can Be Used to Predict the Postoperative Lumbar Cobb Angle Following Selective Thoracic Fusion in Patients with Adolescent Idiopathic Scoliosis.

BACKGROUND: Selective fusion of double curves in patients with scoliosis is considered to spare fusion levels. In 2011, we studied the lumbosacral takeoff angle, defined as the angle between the center-sacral vertical line and a line through the centra of S1, L5, and L4. The lumbosacral takeoff angle was shown to moderately correlate with the lumbar Cobb angle, and a predictive equation was developed to predict the lumbar Cobb angle after selective fusions. The purposes of the present study were to validate that equation in a separate cohort and to assess differences in outcomes following selective and nonselective fusion. METHODS: Patients with Lenke 1B, 1C, 3B, or 3C curve patterns undergoing fusion (both selective and nonselective) with pedicle screw constructs and a minimum of 2 years of follow-up were included. Selective fusion was defined as a lowest level of fixation cephalad to or at the apex of the lumbar curve. To validate the previously derived equation, we used this data set and analysis of variance to check for differences between the actual and calculated postoperative lumbar Cobb angles. Pearson correlation, multiple linear regression, and t tests were used to explore relationships and differences between the selective and nonselective fusion groups. RESULTS: The mean calculated postoperative lumbar Cobb angle (and standard deviation) (22.35° ± 3.82°) was not significantly different from the actual postoperative lumbar Cobb angle (21.08° ± 7.75°), with an average model error of -1.268° (95% confidence interval, -2.649° to 0.112°). The preoperative lumbar Cobb angle was larger in patients with deformities that were chosen for nonselective fusion (50.2° versus 38.9°; p < 0.001). Performing selective fusion resulted in a 3.5° correction of the lumbosacral takeoff angle (p < 0.001), whereas nonselective fusion resulted in a 9.3° correction (p < 0.001). CONCLUSIONS: The lumbosacral takeoff angle can be used to predict the residual lumbar Cobb angle and may be used by surgeons to aid in the decision between selective and nonselective fusion. The change in the lumbosacral takeoff angle following selective fusion is small. Improvement in the lumbosacral takeoff angle and coronal balance is greater in association with nonselective fusion. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Impact of cervical range of motion on the global spinal alignment in ankylosing spondylitis patients with thoracolumbar kyphosis following pedicle subtraction osteotomy.

BACKGROUND CONTEXT: The head's center of gravity (COG) plumb line (PL) and C7 PL could be simultaneously positioned over the pelvis in adult spinal deformity with normal cervical mobility. However, the position of the head in relation to the global spinal alignment has yet to be investigated in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. PURPOSE: The objective of this study was to analyze the position of head in relation to the global spinal alignment in AS-related thoracolumbar kyphosis. STUDY DESIGN/SETTING: Retrospective single-center study. PATIENT SAMPLE: AS patients who underwent lumbar pedicle subtraction osteotomy for thoracolumbar kyphosis from January 2010 to August 2016 were reviewed. Only patients with a visible ear canal on the preoperative, immediate postoperative, and final follow-up radiographs were included. OUTCOME MEASURES: The chin-brow angle, cervical range of motion (ROM), lumbar lordosis (LL), thoracolumbar angle, thoracic kyphosis (TK), L1 pelvic angle, pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), TK+LL+PI, PI-LL, maximal kyphosis (MK), deformity angular rate, T1 pelvic angle, T1 tilt, spinosacral angle, sagittal vertical axis (SVA) COG-C7, SVA COG-femoral head (FH), and SVA C7-S were evaluated. Data regarding the health-related quality of life, including the Oswestry disability index (ODI) and visual analogue scale (VAS)-back score, were also collected preoperatively, 2 years postoperatively, and at the latest follow-up. METHODS: The cohort was divided into patients with occiput-trunk (OT) concordance or with OT discordance according to the SVA COG-C7 ≤30 mm or >30 mm, respectively. There was no funding in this study and there are no conflict of interest-associated biases. RESULTS: A total of 43 patients (36 males and 7 females) with a mean age of 34.2 years (range, 18-59 years) were identified. There were 17 patients accompanied with OT concordance and 26 patients with OT discordance preoperatively. The cervical ROM was significantly lower (24.0° vs 56.1°, p<.001) and SVA COG-C7 was significantly larger (71.7 mm vs 7.4 mm, p<.001) in patients with OT discordance. Furthermore, the PT was larger (41.0° vs 33.5°, p=.010) in patients with OT discordance. After surgery, the whole cohort showed an improvement in LL (-8.6° vs -52.8°, p<.001). Moreover, the CBVA (25.4° vs 1.3°, p<.001) and SVA COG-C7 (46.2 mm vs 21.6 mm, p<.001) were significantly decreased following lumbar PSO. There were 13 patients accompanied with OT discordance postoperatively, and the cervical ROM was still lower (22.5° vs 42.8°, p=.024) in these patients. Postoperative PT was larger (26.5° vs 20.1°, p=.033) in the patients with OT discordance. At the latest follow-up, there were 17 patients accompanied with OT discordance. In these 17 patients, the cervical ROM was significantly lower (21.0° vs 47.0°, p=.001) and PT was significantly higher (26.2° vs 19.2°, p=.012). The ODI and VAS-back scores demonstrated no significant differences between the two groups preoperatively, 2 years postoperatively, or at the latest follow-up. CONCLUSIONS: OT discordance in AS-related thoracolumbar kyphosis could be caused by the reduced cervical ROM. To maintain global spinal balance, the pelvis rotated further backward in response to the larger SVA COG-C7. Moreover, the larger SVA COG-C7 could be decreased after the lumbar PSO. Although there were radiographic differences between the patients with OT concordance and with OT discordance, there was no difference in clinical outcomes, and that a larger sample size and longer follow-up are needed.

The Role of Cross-Links in Posterior Spinal Fusion for Cerebral Palsy-Related Scoliosis.

STUDY DESIGN: Retrospective review of a multicenter, prospective database. OBJECTIVE: Our aim was to compare complication rates and maintenance of radiographic correction at 2 years after posterior spinal fusion (PSF) with or without cross-links in patients with cerebral palsy (CP)-related scoliosis. SUMMARY OF BACKGROUND DATA: Cross-links are frequently used in PSF to correct scoliosis in patients with CP because they are thought to increase the stiffness and torsional rigidity of the construct. METHODS: We reviewed the records of patients with CP who underwent primary PSF with or without cross-links between August 2008 and April 2015. Inclusion criteria were minimum follow-up of 2 years, availability of complications data (implant failure, surgical site infection, revision), and pre- and postoperative measurements of the major curve (measured using the Cobb method). The 256 patients included in this analysis had a mean age of 14.1 ±â€Š2.7 years. Ninety-four patients had cross-links (57% using one cross-link; 43% using two cross-links) and 162 patients did not have cross-links. P < 0.05 was considered statistically significant. RESULTS: The two groups did not differ significantly with regard to sex, age at surgery, preoperative menarche status, Gross Motor Function Classification System level, major curve magnitude, pelvic obliquity, kyphosis, and lordosis angles. There were no significant differences between groups in the correction achieved or the maintenance of correction at 2 years for the major curve, pelvic obliquity, kyphosis, or lordosis (all P > 0.05). Complication rates were similar between the cross-link group (16%, N = 15) and the non-cross-link group (14%, N = 22). CONCLUSION: At 2 years after PSF to treat CP-related scoliosis, patients had no significant differences in the degree of correction achieved, the maintenance of correction, or the rate of complications between those whose fusion constructs used cross-links and those whose constructs did not. LEVEL OF EVIDENCE: 3.

Sagittal balance of the spine.

The static sagittal balance of the normal spine is a physiological alignment of the spine in the most efficient manner by the muscular forces. During gait, this balance is constantly thwarted by single-foot support. This analysis involves the study of parameters which are now well defined. The pelvic incidence is constant, and the sacral slope and the pelvic tilt are positional. The cervical parameters are the upper (O-C2) and lower cervical curvatures (C2-C7), the C7 slope, the spino-cranial angle and the vertical cervical offset. At the thoracic and lumbar level, they are, respectively, kyphosis and lordosis. The OD-HA (odontoid hip axis) angle is the most efficient parameter to analyse the global balance. The average values of these parameters are reported with the new 3D measurements by Le Huec et al. The relationship between these different parameters was analysed, and Roussouly proposed his classification of the different spine shape. Ageing makes it possible to show compensation mechanisms at three levels: spinal, pelvic and lower limbs. Understanding these different data allows for better planning of the surgical management of the patients. Global evaluation of the entire spine and the measurement of the aforementioned parameters allow to determine the extent of the correction to be performed during surgery. Taking these parameters into account also enables us to understand the complications involved in this type of surgery: transitional syndromes or junctional syndromes. Integration of these parameters into the study of gait is an area still under investigation. These slides can be retrieved under Electronic Supplementary Material .

Sarcopenia is related to spinal sagittal imbalance in patients with spinopelvic mismatch.

PURPOSE: To clarify the relationship between sarcopenia and spinopelvic parameters. METHODS: Among outpatients of spine surgery department, 126 patients (mean age 77.2 years. M/F = 71/55) were included. We diagnosed patients with sarcopenia using the diagnostic algorithm of the Asian Working Group for Sarcopenia. Spinopelvic parameters and the prevalence of spinopelvic mismatch (pelvic incidence minus lumbar lordosis ≥ 10°) were investigated and compared between patients with and without sarcopenia. Furthermore, we compared the spinopelvic parameters between the Sarcopenia and No Sarcopenia groups under each condition of spinopelvic match and mismatch. RESULTS: The prevalence of sarcopenia in this study was 21.4%. Overall, the spinopelvic parameters except thoracic kyphosis (TK) (Sarcopenia: 34.7°, No Sarcopenia: 24.3°, p < 0.01) were not significantly different between the Sarcopenia and No Sarcopenia groups. Prevalence of patients with spinopelvic mismatch was also not significantly different between the Sarcopenia and No Sarcopenia groups (37.0% vs. 42.4%, p = 0.66). Among patients without spinopelvic mismatch, there was no spinopelvic parameter with a significant difference between the 2 groups. However, among patients with spinopelvic mismatch, sagittal vertebral axis (SVA) (115.7 mm vs. 58.7 mm, p < 0.01) and TK (36.6° vs. 21.3°, p < 0.01) of the Sarcopenia group were significantly larger than those of the No Sarcopenia group. Moreover, sarcopenia was independently related to a significant increase in SVA (ß = 50.7, p < 0.01) and TK (ß = 14.0, p < 0.01) in patients with spinopelvic mismatch, after adjustment for age. CONCLUSIONS: Sarcopenia is related to spinal sagittal imbalance because of insufficient compensation by flattening thoracic kyphosis in patients with spinopelvic mismatch. These slides can be retrieved under Electronic Supplementary Material.