Objective
To determine the role of dynamic hip joint coverage in maintaining postoperative sagittal balance in adult spinal deformity (ASD) patients following S2-alar-iliac (S2AI) fixation.
Methods
A total of 224 ASD patients who underwent S2AI fixation were enrolled. Patients were stratified into 2 groups based on pre-to-post (from preoperative to postoperative) changes in femoral head coverage (ΔFHC): change group (group C) and noncoverage change group (group NC). Group C was further subdivided according to FHC recovery during follow-up into rebound (group C-R) and nonrebound (group C-NR) groups. Clinical outcomes and radiographic parameters of hip and spinopelvic alignment were assessed preoperatively, at the initial postoperative standing, and at the 2-year follow-up.
Results
Compared to group C, patients in group NC demonstrated a higher incidence of sagittal imbalance-related mechanical complications at 2-year follow-up, with a greater tendency for sagittal imbalance progression (p=0.013), a larger post-to-follow-up change in sagittal vertical axis (ΔSVA) (p=0.029), and a higher incidence of proximal junctional kyphosis (PJK) (p=0.031). Although there was no significant difference in PJK incidence between group C-NR and group C-R (p=0.845), group C-NR showed a greater tendency for postoperative sagittal imbalance aggravation (p=0.025), with a significantly larger ΔSVA during follow-up (p=0.002). The optimal cutoff values for predicting postoperative sagittal imbalance aggravation were 3.5% for pre-to-post ΔFHC (area under the curve [AUC]=0.694) and 1.8% for post-to-follow-up ΔFHC (AUC=0.713).
Conclusion
Dynamic postoperative changes in hip joint coverage, characterized by the FHC, are associated with postoperative sagittal balance maintenance. Patients with limited pre-to-post and post-to-follow-up changes in the FHC demonstrate compromised hip joint compensatory capacity, thereby increasing the risk of postoperative sagittal imbalance-related mechanical complications.

Objective
To compare perioperative and complication outcomes, focusing on the prevention of sagittal translation (ST), between a novel “prioritized correction with multiple-rod construct” (PC-MRC) technique and traditional multiple-rod constructs (M-RC) in adult spinal deformity (ASD) patients undergoing 3-column osteotomies (3-COs).
Methods
In this retrospective study, 101 ASD patients with a minimum 2-year follow-up after 3-COs were divided into 2 groups: PC-MRC (n=65) and M-RC (n=36). The PC-MRC technique involved initial osteotomy closure with short rods followed by global alignment correction with long rods. Radiographic and clinical parameters were assessed preoperatively, postoperatively, and at final follow-up.
Results
The PC-MRC group had significantly shorter operation time and lower estimated blood loss (p=0.045 and p=0.007, respectively). Major coronal and kyphotic deformity correction rates were similar between groups. No significant correction loss occurred at the final follow-up. Crucially, the incidence of ST was significantly lower in the PC-MRC group (1.5% vs. 25.0%, p<0.001). Correspondingly, the overall rate of neurological injury was lower in the PC-MRC group (7.7% vs. 22.2%, p=0.037).
Conclusion
The PC-MRC technique offers a versatile and rigid fixation for 3-COs in ASD patients, facilitating significant correction of global deformity. This straightforward technique effectively prevents massive blood loss and ST caused by 3-COs, while minimizing the risk of neurological complication.

Objective
To assess the effectiveness of vertebral cement augmentation (VCA) at upper instrumented vertebra (UIV) and UIV+1 in preventing proximal junction complications in correction surgery for adult spinal deformity patients.
Methods
A literature search was conducted on Web of Science, PubMed, and Cochrane Library databases for comparative studies published before December 30th, 2024. Two reviewers independently screened eligible articles based on the inclusion and exclusion criteria, assessed study quality with Newcastle-Ottawa scale, and extracted data like study characteristics, surgical details, primary and secondary outcomes. Data analysis was performed using Review Manager 5.4 and Stata software.
Results
Of all 513 papers screened, a meta-analysis was conducted on 7 articles, which included 333 cases in the VCA group and 827 cases in the control group. Patients in the VCA group had significantly older age and lower T score than patients in the control group. Although there was no statistically significant difference in the incidence of proximal junctional failure between the 2 groups, the results of the meta-analysis showed that the incidence of proximal junctional failure and the need for revision surgery were reduced by 36% and 71%, respectively, in the VCA group. One study reported 2 clinically silent pulmonary cement embolism and 1 patient requiring surgical decompression for cement leak into the spinal canal.
Conclusion
This meta-analysis supported the use of VCA in corrective surgery for spinal deformities patients, especially in patients with advanced age and osteoporosis.

Objective
To establish a novel classification system for predicting the risk of intraoperative neurophysiological monitoring (IONM) events in surgically-treated patients with kyphotic deformity.
Methods
Patients with kyphotic deformity who underwent surgical correction of cervicothoracic, thoracic, or thoracolumbar kyphosis in our center from July 2005 to December 2020 were recruited. We proposed a classification system to describe the morphology of the spinal cord on T2-weighted sagittal magnetic resonance imaging: type A, circular/symmetric cord with visible cerebrospinal fluid (CSF) between the cord and vertebral body; type B, circular/oval/symmetric cord with no visible CSF between the cord and vertebral body; type C, spinal cord that is fattened/deformed by the vertebral body, with no visible CSF between the cord and vertebral body. Furthermore, based on type C, the spinal cord compression ratio (CR) < 50% was defined as the subtype C-, while the spinal cord CR ≥ 50% was defined as the subtype C+. IONM event was documented, and a comparative analysis was made to evaluate the prevalence of IONM events among patients with diverse spinal cord types.
Results
A total of 294 patients were reviewed, including 73 in type A; 153 in type B; 53 in subtype C- and 15 in subtype C+. Lower extremity transcranial motor-evoked potentials and/or somatosensory evoked potentials were lost intraoperatively in 41 cases (13.9%), among which 4 patients with type C showed no return of spinal cord monitoring data. The 14 subtype C+ patients (93.3%) had IONM events. Univariate logistic regression analysis showed that patients with a type C spinal cord (subtype C-: odds ratio [OR], 10.390; 95% confidence interval [CI], 2.215–48.735; p = 0.003; subtype C+, OR, 497.000; 95% CI, 42.126– 5,863.611; p < 0.001) are at significantly higher risk of a positive IONM event during deformity correction compared to those with a type A. In further multiple logistic regression analysis, the spinal cord classification (OR, 5.371; 95% CI, 2.966–9.727; p < 0.001) was confirmed as an independent risk factor for IONM events.
Conclusion
We presented a new spinal cord classification system based on the relative position of the spinal cord and vertebrae to predict the risk of IONM events in patients with kyphotic deformity. In patients with type C spinal cord, especially those in C+ cases, it is essential to be aware of potential IONM events, and adopt standard operating procedures to facilitate neurological recovery.