Clinical and radiographic parameters for patients with adult spinal deformity

Background: Improved medical care and increased life expectancy have led to a focus on the impact of adult spinal deformity (ASD) on health-related quality of life (HRQoL) in the field of the spine. Recently, there has been a paradigm shift in the evaluation and management of ASD regarding the important correlation between sagittal imbalance and clinical outcomes.Current Concepts: Loss of lumbar lordosis is recognized as a key driver of ASD followed by forward-leaning of the trunk, reducing thoracic kyphosis, pelvic retroversion, and knee flexion. Radiological assessment has been critical for evaluating ASD from the anteroposterior and lateral view of the whole spine radiograph. Important parameters include coronal, regional, global, and sagittal spinopelvic parameters. Especially, sagittal spinopelvic parameters significantly correlate with disability and HRQoL in patients with ASD, which can influence the process of decision-making with respect to the choice between conservative treatment and surgery.Discussion and Conclusion: Sagittal imbalance has been recently emphasized in patients with ASD. Therefore, the decision-making of ASD treatment should be focused on restoring harmonious alignment to prevent catastrophic complications and improvement of HRQoL.

Bending rod is unnecessary in single-level posterior internal fixation and fusion in treatment of lumbar degenerative diseases

Background Bending rod is a routine in lumbar fusion and fixation surgery, but there is no study investigating whether bending rod in one level is necessary. Methods Patients receiving 1 level lumbar fixation and fusion between May 2018 and September 2020 were included with a minimum 6-month follow-up. The routine of bending rod was omitted during fixation. Preoperative and postoperative radiological parameters were compared. Results There were 67 patients included in the study. Segment lordosis angle increased obviously from 10° (1–39°) to 14° (2–30°) immediately after operation (p = 0.000). T5-T12 increased from 22.97 ± 12.31° to 25.52 ± 11.83° by the 3rd months after surgery (p = 0.011). SS decreased from 35.45 ± 10.47 to 32.19 ± 11.37 in 6-month follow-up (p = 0.038), and PI dropped from 56.97 ± 14.24 to 53.19 ± 12.84 (p = 0.016). ROM of SLA decreased from 4.13 ± 3.14° to 1.93 ± 1.87° at that time point (p = 0.028). Those changes were not seen at 12-month follow-up. No evidence of adjacent vertebral disc degeneration was observed at any time point. Conclusions No sagittal imbalance, dynamic instability or adjacent vertebral degeneration was observed by the 12th month after single-segment posterior lumbar fusion with the use of unbent rods. Bending rod could be omitted in 1-level lumbar fusion to simplify the procedure and reduce operating time.

Clinical Outcomes of S2 Alar-Iliac (S2AI) Screw Technique in The Treatment of Severe Spinal Sagittal Imbalance: A Retrospective 2-Year Follow-Up Study

Background The treatment of adult spinal deformity (ASD) remains a significant challenge, especially in elderly patients. This study aimed to evaluate the outcomes of the S2AI screw technique in the treatment of severe spinal sagittal imbalance with a minimum 2-year follow-up. Methods From January 2015 to December 2018, 23 patients with severe degenerative thoracolumbar kyphosis who underwent placement of S2AI screws for long segment fusion were retrospectively reviewed. Patients were divided into group A (no mechanical complications, 13 cases) and group B (with mechanical complications, 10 cases) according to the occurrence of mechanical complications at the last follow-up. Radiographic parameters were compared between groups preoperatively, 1 month postoperatively, and at the last follow-up. Risk factors for mechanical complications were analyzed. Results The incidence of mechanical complications was 43.5%, and the revision rate was 17.4%. At 1 month postoperatively, sagittal correction was better in group A than in group B (P<0.05). The lumbar lordosis (LL), pelvic incidence minus lumbar lordosis (PI-LL), T1 pelvic angle (TPA), and sagittal vertical axis (SVA) of both groups at the last follow-up were significantly different from corresponding values at 1 month postoperatively (P<0.05), and the sagittal correction was partially lost. Pearson correlation analysis revealed that the occurrence of mechanical complications was associated with sacral slope (SS), LL, PI-LL, and global alignment and proportion (GAP) score at 1 month postoperatively. Conclusion A high incidence of mechanical complications was observed in long-segment corrective surgery with the S2AI screw technique for severe spinal sagittal imbalance. Inadequate sagittal correction is a risk factor for the development of mechanical complications.

Does obesity affect acetabular cup position, spinopelvic function and sagittal spinal alignment? A prospective investigation with standing and sitting assessment of primary hip arthroplasty patients

Background Total hip arthroplasty (THA) instability is influenced by acetabular component positioning, spinopelvic function and sagittal spinal alignment. Obesity is considered as a risk factor of THA instability, but the causal relationship remains unknown. This study aimed to investigate the influence of BMI on (1) spinopelvic function (lumbar flexibility, pelvic mobility and hip motion), (2) sagittal spinal alignment pre- and postoperatively and (3) acetabular cup position postoperatively in primary THA patients in a prospective setting. Methods One hundred ninety patients receiving primary total hip arthroplasty were enrolled in a prospective cohort study and retrospectively analysed. All patients received stereoradiography (EOS) in standing and relaxed sitting position pre-and postoperatively. C7-sagittal vertical axis (C7-SVA), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), anterior plane pelvic tilt (APPT), and pelvic femoral angle (PFA) were assessed. Key parameters of the spinopelvic function were defined as lumbar flexibility (∆ LL = LLstanding − LLsitting), pelvic mobility (∆ PT = PTstanding − PTsitting) and hip motion (∆ PFA = PFAstanding − PFAsitting). Pelvic mobility was further defined based on ∆ PT as stiff, normal and hypermobile (∆ PT < 10°; 10°–30°; > 30°). The patients were stratified to BMI according to WHO definition: normal BMI ≥ 18.5–24.9 kg/m2 (n = 68), overweight ≥ 25.0–29.9 kg/m2 (n = 81) and obese ≥ 30–39.9 kg/m2 (n = 41). Post-hoc analysis according to Hochberg's GT2 was applied to determine differences between BMI groups. Results Standing cup inclination was significant higher in the obese group compared to the normal BMI group (45.3° vs. 40.1°; p = 0.015) whereas standing cup anteversion was significantly decreased (22.0° vs. 25.3°; p = 0.011). There were no significant differences for spinopelvic function key parameter lumbar flexibility (∆ LL), pelvic mobility (∆ PT) and hip motion (∆ PFA) in relation to BMI stratified groups. The obese group demonstrated significant enhanced pelvic retroversion compared to the normal BMI group (APPT − 1.8° vs. 2.4°; p = 0.028). The preoperative proportion of stiff pelvic mobility was decreased in the obese group (12.2%) compared to normal (25.0%) and overweight (27.2%) groups. Spinal sagittal alignment in C7-SVA and PI-LL mismatch demonstrated significantly greater imbalance in the obese group compared to the normal BMI group (68.6 mm vs. 42.6 mm, p = 0.002 and 7.7° vs. 1.2°, p = 0.032, respectively) The proportion of patients with imbalanced C7-SVA was higher in the obese (58.5%) than in the normal BMI group (44.1%). Conclusions The significantly increased spinal sagittal imbalance with altered pelvic mechanics is a potential cause for the reported increased risk of THA dislocations in obese patients. Consequently, the increased spinal sagittal imbalance in combination with normal pelvic mobility need to be taken into account when performing THA in obese patients.

Clinical, Radiographic, and Genetic Analyses in a Population-Based Cohort of Adult Spinal Deformity in the Older Population

Objective: This study aimed to identify the sagittal parameters associated with health-related quality of life and genetic variations that increase the risk of adult spinal deformity (ASD) onset in the older population.Methods: We recruited 120 participants who had a sagittal vertical axis > 50 mm in a sagittal imbalance study. Sagittal radiographic parameters, cross-sectional area, and intramuscular fatty infiltration using the Goutallier classification in the paraspinal lumbar muscles were evaluated. Functional scales included the self-reported Oswestry Disability Index (ODI), 36-item Short Form Health Survey (SF-36), and visual analogue scales (VAS) for back and leg pain. We performed whole-exome sequencing and an exome-wide association study using the 100 control subjects and 63 individuals with severe phenotypes of sagittal imbalance.Results: Pelvic incidence minus lumbar lordosis (PI–LL) mismatch was negatively associated with the SF-36 and positively correlated with ODI and VAS for back and leg pain. PI–LL was related to the quality and size of the paraspinal muscles, especially the multifidus muscle. We identified common individual variants that reached exome-wide significance using single-variant analysis. The most significant single-nucleotide polymorphism was rs78773460, situated in an exon of the SVIL gene (odds ratio, 9.61; p = 1.15 × 10-9).Conclusion: Older age, higher body mass index, and a more significant PI–LL mismatch were associated with unfavorable results on functional scales. We found a genetic variation in the SVIL gene, which has been associated with the integrity of the cytoskeleton and the development of skeletal muscles, in severe ASD phenotypes. Our results help to elucidate the pathogenesis of ASD.

Thoracolumbar Slope Is Useful Parameter for Evaluating HealthRelated Quality of Life and Sagittal Imbalance Aggravation in Adult Spinal Deformity: A Prospective Observational Cohort Study

Objective: The purpose of the present study was to evaluate the natural course of primary degenerative sagittal imbalance (PDSI), its aggravating factors, and health-related quality of life (HRQoL) associated with various spinal alignment parameters (SAPs) in patients with PDSI who have not undergone surgery.Methods: One hundred three participants volunteered to participate. The SAPs, including T1 pelvic angle (T1PA), thoracolumbar tilt, and thoracolumbar slope (TLS), were measured on whole-spine standing radiographs. The back and lumbar muscle volumes were measured. To determine HRQoL at baseline and at 2-year follow-up, face-to-face questionnaires were administered, which included visual analogue scale of the back and leg, physical component summary/mental component summary of 36-item Short Form Health Survey, Oswestry Disability Index (ODI), and Mini-Mental State Examination.Results: Overall HRQoL measures had improved after 2 years of follow-up compared to baseline. PDSI aggravation was observed in 18 participants (26.1%). TLS, sagittal vertical axis (SVA), and T1PA were strongly correlated with each other. TLS, SVA, and T1PA were correlated with ODI score. Among them, TLS was most highly correlated with ODI score. TLS greater than -3.5° was a predicting factor for PDSI aggravation (p = 0.034; 95% confidence interval, 1.173–63.61; odds ratio, 8.636).Conclusion: The present study implied that PDSI does not necessarily worsen with aging. TLS is an appropriate parameter for assessing the clinical situation in patients with PDSI. Furthermore, a TLS greater than -3.5° predicts PDSI aggravation; thus, TLS may be a useful parameter for predicting prognosis in PDSI.