Does global spinal alignment affect the use of walking aids after multi-segment spinal fixation for patients with ASD? A multicenter retrospective study.

PURPOSE: This study aimed to clarify the relation between global spinal alignment and the necessity of walking aid use in patients with adult spinal deformity (ASD) and to investigate the impact of spinal fixation on mobility status after surgery. METHODS: In total, 456 older patients with ASD who had multi-segment spinal fixation surgery and were registered in a multi-center database were investigated. Patients under 60 years of age and those unable to walk preoperatively were excluded. Patients were classified by their mobility status into the independent, cane, and walker groups. Comparison analysis was conducted using radiographic spinopelvic parameters and the previously reported global spine balance (GSB) classification. In addition, preoperative and 2 years postoperative mobility statuses were investigated. RESULTS: Of 261 patients analyzed, 66 used walking aids (canes, 46; walkers, 20). Analysis of preoperative radiographical parameters showed increased pelvic incidence and pelvic incidence-lumbar lordosis mismatch in the walker group and increased sagittal vertebral axis in the cane and walker groups versus the independent group. Analysis of GSB classification showed a higher percentage of walker use in those with severe imbalance (grade 3) in the sagittal classification but not in the coronal classification. While postoperative radiographical improvements were noted, there was no significant difference in the use of walking aids before and 2 years after surgery (P = 0.085). CONCLUSION: A significant correlation was found between "sagittal" spinal imbalance and increased reliance on walking aids, particularly walkers. However, the limitation of improvement in postoperative mobility status suggested that multiple factors influence the mobility ability of elderly patients with ASD.

Longitudinal impact of multi-segment spinal fixation surgery on mobility status and clinical outcomes in adult spinal deformity: a multicenter retrospective study.

PURPOSE: To investigate changes in postoperative mobility status in patients with ASD, and the determining factors that influence these changes and their impact on clinical outcomes, including the rate of home discharge and long-term mobility. METHODS: A total of 299 patients with ASD who underwent multi-segment posterior spinal fusion were registered in a multi-center database were investigated. Patient mobility status was assessed using walking aids and classified into five levels (1: independent, 2: cane, 3: walker, 4: assisted, and 5: wheelchair) preoperatively, at discharge, and after 2 years. We determined improvements or declines in the patient's mobility based on changes in the classification levels. The analysis focused on the factors contributing to the deterioration of postoperative mobility. RESULTS: Two years postoperatively, 87% of patients maintained or improved mobility. However, 27% showed decreased mobility status at discharge, associated with a lower rate of home discharge (49% vs. 80% in the maintained mobility group) and limited improvement in mobility status (35% vs. 5%) after 2 years. Notably, postoperative increases in thoracic kyphosis (7.0 ± 12.1 vs. 2.0 ± 12.4°, p = 0.002) and lower lumbar lordosis (4.2 ± 13.1 vs. 1.8 ± 12.6°, p = 0.050) were substantial factors in mobility decline. CONCLUSION: Postoperative mobility often temporarily decreases but generally improves after 2 years. However, an overcorrection in sagittal alignment, evidenced by increased TK, could detrimentally affect patients' mobility status. Transient mobility decline associated with overcorrection may require further rehabilitation or hospitalization. Further studies are required to determine the biomechanical effects of surgical correction on mobility.

Preoperative low Hounsfield units in the lumbar spine are associated with postoperative mechanical complications in adult spinal deformity.

PURPOSE: To determine the most valid bone health parameter to predict mechanical complications (MCs) following surgery for adult spinal deformity (ASD). METHODS: This multicenter study retrospectively examined the records of patients who had undergone fusion of three or more motion segments, including the pelvis, with a minimum two-year follow-up period. Patients with moderate and severe global alignment and proportion scores were included in the study and divided into two groups: those who developed MCs and those who did not. Bone mineral density (BMD) of the lumbar spine and femoral neck was measured using dual-energy X-ray absorptiometry, and Hounsfield units (HUs) were measured in the lumbar spine on computed tomography. Radiographic parameters were evaluated preoperatively, immediately after surgery, and at final follow-up. RESULTS: Of 108 patients, 30 (27.8%) developed MCs, including 26 cases of proximal junctional kyphosis/failure, 2 of distal junctional failure, 6 of rod fracture, and 11 reoperations. HUs were significantly lower in patients who experienced MCs (113.7 ± 41.1) than in those who did not (137.0 ± 46.8; P = 0.02). BMD did not differ significantly between the two groups. The preoperative and two-year postoperative global tilt, as well as the immediately postoperative sagittal vertical axis, were significantly greater in patients who developed MCs than in those who did not (P = 0.02, P < 0.01, and P = 0.01, respectively). CONCLUSION: Patients who experienced MCs following surgery for ASD had lower HUs than those who did not. HUs may therefore be more useful than BMD for predicting MCs following surgery for ASD.

An appropriate method for predicting the femoral angle on whole-body X-ray images from full-spine X-ray images.

INTRODUCTION: The importance of lower-limb compensation in patients with spinal malalignment due to spinal pathologies has been emphasized. The latest whole-body X-ray images (WBX) have enabled evaluations of whole-body alignment from head to toe. However, WBX is still not commonly available. Thus, the present study aimed to examine an alternative measurement method of the femoral angle on usual full-spine X-ray images (FSX) that approximates the femoral angle on WBX. METHODS: A total of 50 patients (age, 52.8 ± 25.3 years; female, n = 26; male, n = 24) underwent WBX and FSX. The following parameters were measured on lateral view X-rays: WBX and FSX femoral angle (angle between the femoral axis and a perpendicular line); FSX femoral distance (distance from the center of femoral head to the distal femur on FSX); WBX intersection length (length between the center of the femoral head and the intersection point [the point at which the line connecting the center of the femoral head and the midpoint of the femoral condyle intersects the center line of the femur] on WBX). RESULTS: The WBX femoral angle, and FSX femoral angle were 0.16 ± 4.2°, and -0.53 ± 4.1°, respectively. The FSX femoral distance was 102.7 ± 41.1 mm. An ROC curve analysis revealed that the cut-off value of the FSX femoral distance associated with minimal difference in the WBX and FSX femoral angles (<3°) was 73 mm (sensitivity 83.3%, specificity 87.5%, AUC 0.80). The WBX intersection length was 105.3 ± 27.3 mm. CONCLUSION: To calculate the femoral angle on FSX that approximates the WBX femoral angle, the femoral distance on FSX ≥73 mm is preferable. We suggest using the FSX femoral distance within the range of 80 mm-130 mm as a simple numerical value that meets all criteria.

Impact of Obesity, Osteopenia, and Scoliosis on Interobserver Reliability of Measures of the Spinopelvic Sagittal Radiographic Parameters.

Introduction: We investigated the relationships between patient factors, including obesity, osteopenia, and scoliosis, and the reliability of measures of the spinopelvic sagittal parameters using conventional X-radiography (Xp) and slot-scanning Xp devices (EOS) and examined the differences in interobserver measurement reliability between them. Methods: We retrospectively enrolled 55 patients (52.7±25.3 years, 27 females) with conventional whole-spine Xp and EOS images taken within three months. Patients were classified according to obesity (Body mass index≥25 kg/m2), osteopenia (T score<-1), and scoliosis (Cobb angle>20°). The associations between patient factors and reliability of radiological parameter measurements were examined with interobserver intraclass correlation coefficient (ICC), defined as poor, <.40; good, 40-.79; and excellent, ≥.80. Results: All parameters measured with EOS showed excellent reliability except for L4-S (ICC:.760, 95% CI:.295-.927) in the obesity+ group. All parameters measured with conventional Xp were excellent except for those classified as good: L4-S (.608,.093-.868) and pelvic incidence (PI) (.512,.078-.832) in the obese+ group; T1 slope (.781,.237-.952), L4-S (.718,.112-.936), sacral slope (SS) (.792,.237-.955), pelvic tilt (PT) (.787,.300-.952), and center of acoustic meatus and femoral head offset (CAM-HA) (.690,.090-.928) in the osteopenia+ group; and lumbar lordosis (LL, L4-S) (.712,.349-.889), SS (.608,.178-.843), and CAM-HA (.781,.480-.917) in the scoliosis+ group. Conclusions: Reliability of EOS measurements was preferable except for L4-S in patients with obesity. The reliability of conventional Xp measurements of pelvic parameters SS, PT, and PI was affected by patient factors, including obesity, osteopenia, and scoliosis. When evaluating lower lumbar and pelvic parameters in patients with these factors, we recommend substituting thoracic parameters, LL (L1-S), sagittal vertical axis (SVA), and T1 pelvic angle (TPA), or combining computed tomography (CT) measurements.