Objective: To investigate the status of heat illness, knowledge awareness and adaptive behaviors of heat wave knowledge among food delivery riders, so as to provide a basis for optimizing heat wave response measures for food delivery riders. Methods: In November 2022, food delivery riders from a large food delivery platform in Ningbo City, Zhejiang Province were selected as survey subjects using a cluster sampling method. A self-designed electronic questionnaire was used to select demographic information, work status, lifestyle behaviors and disease history, heat illness status, knowledge awareness and adaptive behaviors of heatwave. Results: A total of 911 questionnaires were distributed, and 830 valid questionnaires were recovered, resulting in a valid response rate of 91.11%. Among the respondents, 796 (95.90%) were male, and 818 (98.55%) worked full-time. The mean age was (27.75±8.00) years. A total of 470 respondents (56.63%) had a work tenure of less than 1 year. The primary working hours were 8-<12 hours, with 504 people accounting for 60.72%. There were 108 cases of heatstroke, with an occurrence rate of 13.01%. And 286 people reported heat-related symptoms, with an occurrence rate of 34.46%. The overall awareness rate of heat wave knowledge was 73.22%, while the awareness rate of heat warning signal classification was relatively low at 9.04%. The heat wave cognition score was (5.86±1.31) points. There were statistically significant differences in heat wave cognition scores among food delivery riders of different ages, educational levels, family annual income, work tenures, and work durations (all P<0.05). Regarding positive adaptive behaviors, the number of riders paying attention to weather forecasts and actively learning about preventive measures was higher (734 people each, accounting for 88.43%). Regarding negative adaptive behaviors, the number of riders who often drank ice-cold beverages was higher (509 people, accounting for 61.33%). The heat wave adaptive behavior score was (6.88±1.77) points. There were statistically significant differences in adaptive behavior scores among riders with different educational levels, family annual income, work tenures, and smoking frequency (all P<0.05). Conclusions The occurrence rates of heatstroke and heat-related symptoms among food delivery riders are relatively high. The knowledge awareness and adaptive behaviors regarding heat wave are at a moderate level. It is suggested to strengthen health education, reinforce risk cognition of heat wave, and promote positive adaptive behaviors among food delivery riders.

Objective This study conducted molecular biological identification of the viruses carried by Culex pipiens pallens specimens collected in Shunyi District, Beijing in 2023, and observed the changes in the infection rate of the viruses carried by Cx. pipiens pallens at different collection times. Methods Cx. pipiens pallens were collected using carbon dioxide mosquito traps. The mosquito samples were ground in batches and analyzed by molecular biology technologies. The virus infection rate at different collection times was analyzed statistically. Results 17 strains of Culex pipiens pallens densovirus(CppDNV)were identified from Cx. pipiens pallens samples collected in Shunyi District, Beijing, in 2023. The nucleotide sequence analysis of the virus genome coding region showed that CppDNV was a single-stranded DNA virus with a total length of 3 335 nt, encoding 2 non-structural proteins(NS1, NS2)and 1 capsid protein(VP). The nucleotide(amino acid)sequence lengths of the three proteins were 2 376 nt(791 aa),1 092 nt(363 aa)and 1 071 nt(356 aa), respectively. Phylogenetic analysis showed that CppDNV was located in genus Brevihamaparvovirus. Statistical analysis showed no significant difference in infection rates across collection times(χ2=4.429, P=0.194). Conclusions CppDNV was identified in Cx. pipiens pallens in Beijing, and it was stably maintained in this natural population.

Objective:To compare the clinical efficacy of Minimally Invasive Surgery (MIS) and traditional Posterior Spinal Fusion (PSF) in treating children with paralytic scoliosis with pelvic obliquity (PSPO) following spinal cord injury.Methods:A retrospective analysis was conducted on the data of 25 patients with PSPO who underwent surgical treatment at the Drum Tower Hospital affiliated with Nanjing University Medical School from January 2017 to June 2023. The cohort included 4 males and 21 females, aged 12.3±2.8 years (range 9-14 years). Patients were divided into the MIS group (12 cases) and the PSF group (13 cases). Radiological parameters were measured preoperatively, postoperatively, and at the last follow-up. Surgical time, intraoperative blood loss, intraoperative blood transfusion volume, length of hospital stay, total hospitalization costs, and complications were recorded. The Scoliosis Research Society questionnaires-22 (SRS-22) Chinese version were used to assess patient satisfaction and efficacy.Results:There were no statistically significant differences between the MIS and PSF groups in age, gender, Risser sign, preoperative Cobb angle for scoliosis, pelvic tilt angle, or local kyphosis angle ( P>0.05). The MIS group demonstrated surgical time of 176±30 minutes, intraoperative blood loss of 300±70 ml, blood transfusion volume of 280±175 ml, and total hospitalization costs of 87'800± 13'300 yuan, all of which were lower than PSF group, with values of 280±91 minutes, 1'433±116 ml, 1'351±996 ml, and 14'8400±26'100 yuan, respectively. These differences were statistically significant ( t=3.789, P=0.001; t=29.328, P<0.001; t=3.667, P=0.001; t=7.271, P<0.001). In the MIS group, preoperative, postoperative, and last follow-up Cobb angles were 79.11°±6.74°, 35.86°±4.98°, and 36.27°±4.84° respectively; pelvic tilt angles were 24.79°±5.58°, 9.18°±3.32°, and 8.79°±2.94°; local kyphosis angles were 38.84°±4.18°, 12.96°±4.87°, and 11.43°±6.08°, respectively. Postoperative and last follow-up angles were significantly reduced compared to preoperative values, with statistically significant differences ( P<0.05). In the PSF group, preoperative, postoperative, and last follow-up Cobb angles were 82.06°±9.26°, 34.75°±5.14°, and 35.15°±5.04° respectively; pelvic tilt angles were 26.60°±6.21°, 10.12°±3.21°, and 9.91°±2.97°; local kyphosis angles were 40.92°±7.04°, 10.92°±7.26°, and 14.02°±5.58°, respectively. Differences from preoperative to postoperative measurements were statistically significant ( P<0.05). At the last follow-up, both groups showed no significant loss of scoliosis correction, and there were no statistically significant differences between the groups postoperatively or at the last follow-up ( P>0.05). In the MIS group, one case of superficial surgical site infection and one case of postoperative atelectasis occurred. In the PSF group, two cases of deep surgical site infection, one case of poor screw placement, and two cases were transferred to the ICU postoperatively due to excessive intraoperative bleeding. Preoperative SRS-22 total scores were 2.0±0.6 for PSF and 2.1±0.4 for MIS. Postoperative SRS-22 total scores (excluding satisfaction) were 3.0±0.5 for PSF and 2.9±0.3 for MIS. The within-group differences from preoperative to postoperative were statistically significant ( P<0.05), while the between-group differences from preoperative to postoperative were not statistically significant ( P>0.05). Conclusion:Compared to the PSF technique, MIS can shorten surgery time, reduce intraoperative blood loss and perioperative complications, and decrease hospitalization costs. MIS can achieve similar early clinical efficacy.

Objective:To explore a selective resection strategy for combined lumbosacral hemivertebra (LSHV) and thoracolumbar hemivertebra/lumbar hemivertebra (TLHV/LHV) double-balanced hemivertebra deformities.Methods:A retrospective analysis was conducted on 21 patients aged over 10 years with lumbosacral and thoracolumbar or lumbar combined hemimetameric segmental shift (HMMS) deformities who underwent surgery at Nanjing Drum Tower Hospital between May 2009 and October 2022. The cohort included 7 males and 14 females, with a mean surgical age of 21.5±10.9 years (range: 12-55 years) and a mean follow-up duration of 32.8±15.9 months (range: 24-74 months). Patients were divided into two groups based on preoperative coronal balance: the balanced group (Type A) and the unbalanced group (Type C). Radiographic parameters, including the major Cobb angle, lumbosacral take-off angle, kyphotic angle, coronal balance distance (CBD), and the deviation of the upper instrumented vertebra (UIV), were measured preoperatively, postoperatively, and at the final follow-up. Surgical complications were also recorded.Results:Of the 21 patients, 11 were classified as preoperatively balanced, and 10 as unbalanced. The deformity angular ratio of thoracolumbar to lumbosacral curves was significantly higher in the balanced group than in the unbalanced group (0.9±0.3 vs. 0.6±0.2; t=2.143, P=0.045). The preoperative main curve Cobb angles in the balanced and imbalanced groups were 71.3°±22.3° and 58.6°±8.2°, respectively. One week postoperatively, these angles were reduced to 38.4°±17.6° and 31.3°±5.6°, and were maintained at 40.0°±18.1° and 32.6°±5.6° at the final follow-up, all differences were statistically significant ( P<0.05). The preoperative lumbosacral take-off angles were 37.5°±9.1° in the balanced group and 36.7°±7.7° in the imbalanced group, which decreased to 18.4°±9.4° and 19.2°±5.5° at 1 week postoperatively, and remained at 19.4°±10.1° and 19.6°±5.8° at the final follow-up. These changes were also statistically significant ( P<0.05). In the balanced group, the UIV tilt angle, the CBD and the deviation of the UIV, were all significantly reduced compared to preoperative values ( P<0.05). Among the 21 patients, LSHV resection was performed in 15 cases, and TLHV/LHV resection was performed in 7 cases. Among the 15 patients with kyphosis, TLHV/LHV resection was performed in 6 cases. In the balanced group, 9 patients maintained type A postoperatively, including 4 patients with LSHV resection, 2 with TLHV/LHV resection, 2 with both LSHV and TLHV/LHV resection, 1 without resection of both hemivertebra. Two patients in the balanced group who underwent TLHV/LHV resection experienced postoperative deterioration to type C. In the unbalanced group, 8 cases with LSHV resection improved to type A, while 1 case with LSHV resection and 1 case with neither resection maintained C-type. In the LSHV resection group, CBD improved from 29.8±15.2 mm to 13.9±5.7 mm postoperatively and remained stable at 14.6±8.6 mm at final follow-up. Only 1 patient in this group experienced worsened coronal imbalance. In contrast, in the non-LSHV resection group, CBD worsened from 17.2 ± 8.7 mm to 19.7±12.1 mm postoperatively, progressing further to 20.5±13.0 mm at follow-up. Three patients in this group had worsening coronal imbalance, and 2 required revision surgery. Reported complications included 3 cases of internal fixation fracture, 1 case of proximal junctional kyphosis, and 1 case of acute incision infection. Conclusions:Effective resection of lumbosacral hemivertebrae is the preferred selective strategy, particularly for patients with preoperative coronal imbalance, as it significantly reduces the risk of worsening coronal imbalance and internal fixation-related complications. However, selective resection involving only TLHV or LHV without addressing LSHV in preoperatively balanced patients may increase the risk of postoperative coronal imbalance.

Objective:To investigate the effect of anterior and posterior selective fusion strategy on evolution of coronal pattern in patients with Lenke 5C adolescent idiopathic scoliosis (AIS) and whether upper end vertebra (UEV)-1 strategy in anterior surgery would have an effect on postoperative coronal balance.Methods:A total of 108 Lenke 5C AIS patients with at least 2 years follow-up who underwent anterior or posterior selective thoracolumbar fusion surgery from January 2005 to December 2020 were enrolled, with 51 patients in the anterior group and 57 patients in the posterior group. The patients were categorized into three groups (type A, C 7PL-CSVL<20 mm; type B, C 7PL-CSVL ≥20 mm with C 7PL toward the concave side of the main curve; and type C, C 7PL-CSVL≥20 mm with C 7PL toward the convex side of the main curve) to investigate the evolution of coronal balance of each preoperative coronal pattern at the anterior and posterior groups. Parameters such as thoracolumbar Cobb angle, rate of coronal imbalance, and SRS-22 score were recorded at preoperative, 1 week postoperatively, and final follow-up in both groups. Results:The differences of basic date between the two groups were not statistically significant except for the fusion level (5.2±0.7 vs. 5.6±0.9, t=2.497, P=0.014). In the anterior group, a total of 27 patients with preoperative type A, 23 patients with preoperative type A maintained type A at the 1 week postoperatively, and 2 of them were converted to type C at the final follow-up. Four patients with preoperative type A converted to type C at the 1 week postoperatively, and all of them returned to type A at the final follow-up. A total of 23 patients with preoperative type C, four patients with preoperative type C maintained type C at the 1 week postoperatively, and one of them maintained type C at the final follow-up. Nineteen patients with preoperative type C converted to type A at the 1 week postoperatively, and all of them maintained type A at the final follow-up. In the posterior group, a total of 26 patients with preoperative type A, 22 patients with preoperative type A maintained type A at the 1 week postoperatively, and only 2 of these patients converted to type C at the final follow-up. Four of the preoperative type A patients converted to type C at the 1 week postoperatively, and all of them returned to type A at the final follow-up. A total of 29 patients with preoperative type C, thirteen patients with preoperative type C maintained type C at the 1 week postoperatively, and 7 of them maintained type C at the last follow-up. Sixteen patients with preoperative type C converted to type A at the 1 week postoperatively, of whom two converted to type C at the final follow-up. For patients with preoperative type C the rate of coronal imbalance was significantly lower in the anterior group than in the posterior group both in the immediate postoperative period (17% vs. 45%, P<0.05) and at the final follow-up (4% vs. 31%, P=0.038). The rate of coronal imbalance at final follow-up was significantly lower in the UEV-1 group than in the UEV group in the posterior approach (3% vs. 38%, P<0.05), and there was no difference between the two groups in the anterior approach. There were no significant differences in radiographic parameters and SRS-22 scores between the two groups, except for the thoracic Cobb angle at the final follow-up, which was greater in the anterior group than in the posterior group at the final follow-up (19.5±7.3 vs.16.4±5.6, t=2.427, P=0.017). Multivariate logistic regression analysis revealed that anterior surgery and Risser were risk factors for postoperative CIB of preoperative type C ( OR=21.138, P=0.030 and OR=0.406, P=0.048 respectively). Conclusion:For patients with preoperative type A, both anterior and posterior procedures lead to a satisfactory reconstruction of coronal balance. In patients with preoperative type C, anterior surgery acquire a better reconstruction of coronal balance. The strategy of proximal UEV-1 was similar to the strategy of UEV in terms of restoring coronary balance in anterior approach and it was unable to lower the rate of postoperative coronal imbalance. In contrast, UEV-1 strategy in posterior surgery was effective in reducing the rate of postoperative coronal imbalance.

Objective:To investigate the impact of correcting rotational subluxation through circumferential fusion and transforaminal lumbar interbody fusion (TLIF) on postoperative coronal plane imbalance in degenerative scoliosis.Methods:A retrospective analysis was conducted on the data of 108 patients with type A degenerative scoliosis in the Nanjing classification who underwent primary multi-segment posterior column osteotomy (PCO) with deformity correction and internal fixation at Nanjing Gulou Hospital from June 2017 to June 2021. Patients were divided into two groups based on the presence of preoperative rotational subluxation: the rotational subluxation group and the non-rotational subluxation group. The rotational subluxation group consisted of 60 patients, with 8 males and 52 females, aged 63.7±5.5 years (range, 56-75 years). The non-rotational subluxation group included 48 patients, with 5 males and 43 females, aged 64.4±5.2 years (range, 53-72 years). Within the rotational subluxation group, depending on whether TLIF was performed on the rotational subluxation segment, they were further categorized into the TLIF group and the PCO group. The TLIF group comprised 28 patients, while the PCO group had 32 patients. Full-spine anteroposterior and lateral X-rays were taken preoperatively, postoperatively, and at the last follow-up to measure coronal balance types and radiographic parameters. The differences in the lumbar Cobb angle, coronal balance distance (CBD), and the Cobb angle of the lumbosacral curve (Cobb-Fra angle) were compared between the rotational subluxation group and the non-rotational subluxation group, as well as between the TLIF group and the PCO group.Results:The average surgery duration ranged from 200 to 310 min, with a mean of 235±47 min. The intraoperative blood loss ranged from 700 to 2,400 ml, with an average of 950±355 ml. The number of fused segments in the rotational subluxation group was 7.6±2.1, ranging from 5 to 11 segments, while in the non-rotational subluxation group, it was 7.4±2.0, ranging from 5 to 10 segments. Postoperatively, 13%(8/60) of patients in the rotational subluxation group developed type C coronal imbalance, significantly higher than the 2%(1/48) in the non-rotational subluxation group. The immediate postoperative and final follow-up lumbar Cobb angles, CBD, and Cobb-Fra angles in the rotational subluxation group were 20.60°±10.73° and 20.33°±10.92°, 22.53±16.45 mm and 18.53±17.31 mm, 13.14°±4.40° and 11.23°±4.92°, respectively, which were higher than those in the non-rotational subluxation group (13.92°±7.02° and 12.92°±6.64°, 18.62±17.44 mm and 8.83±8.95 mm, 11.91°±3.03° and 9.52°±3.30°), with statistical significance ( P<0.05).. Among patients in the rotational subluxation group, the probability of new-onset coronal imbalance postoperatively was 4%(1/28) in the TLIF group, which was lower than the 22%(7/32) in the PCO group, with a statistically significant difference (χ 2=4.330, P=0.037). The immediate postoperative and final follow-up lumbar Cobb angles, CBD, and Cobb-Fra angles in the PCO group were 25.63°±11.00° and 25.13°±11.04°, 27.37±18.95 mm and 25.25±18.67 mm, 15.50°±3.62° and 14.08°±4.77°, respectively, which were significantly higher than those in the TLIF group (14.86°±6.96° and 14.86°±5.37°, 17.08±10.94 mm and 10.86±7.86 mm, 10.14°±3.37° and 8.46°±2.66°), with statistical significance ( P<0.05). Conclusion:For patients with Type A degenerative scoliosis combined with rotational subluxation according to the Nanjing classification, performing a 360-degree circumferential release and interbody fusion at the segment with rotatory subluxation can reduce the risk of developing new postoperative coronal imbalances.

Objective:To compare the efficacy and safety of SRS-Schwab grade 4 osteotomy and vertebral column resection (VCR) in the surgical correction of type II congenital kyphosis (CK).Methods:A retrospective review was conducted on clinical and radiographic data from patients with type II CK who underwent corrective surgery at Nanjing Drum Tower Hospital between June 2008 and December 2021. Patients were divided into two groups based on the osteotomy technique employed: the VCR group (21cases) and the SRS-Schwab grade 4 osteotomy group (19 cases). Clinical parameters, including operative duration, estimated blood loss (EBL), number of segmentation failure levels, number of fused segments, and the use of anterior support cages, were compared between groups. Radiographic parameters included the number of segmentation fusion and measurements of segmental kyphosis (SK) preoperatively, postoperatively, and at the final follow-up. The degree and rate of SK correction were also calculated and compared. Complications such as neurophysiological monitoring events, neurological injury, implant breakage, proximal junctional kyphosis/lordosis (PJK/PJL), sagittal translation (ST), and implant failure were recorded. Additionally, SRS-22 questionnaire scores were assessed preoperatively, postoperatively, and at the latest follow-up.Results:A total of 40 patients were included, with a mean follow-up duration of 48.96±21.31 months (range, 24-96 months). Compared to the SRS-Schwab group, the VCR group had significantly more levels of segmentation defect (3.85±0.79 vs. 2.68±0.54), required more fused segments (8.00±2.23 vs. 5.47±2.04), had longer operative time (358.71±77.06 min vs. 212.52±77.05 min), and greater EBL (963.66±278.49 ml vs. 698.94±222.20 ml), all with statistically significant differences ( P<0.05). No significant differences were observed in local kyphotic angle, correction magnitude, or correction rate between groups postoperatively (P>0.05). Among patients with ≤48 months of follow-up, the SRS-Schwab group showed significantly lower SK (13.00°±16.28° vs. 34.00°±21.37°) and a higher correction rate (82.52%±21.40% vs. 52.84%±24.67%) at final follow-up ( P<0.05). However, no significant differences were observed in patients with >48 months of follow-up ( P>0.05), or in the overall cohort regardless of follow-up duration ( P>0.05). Complication rates were comparable between groups ( P>0.05). One neurophysiological monitoring event, 1 neurological injury, 3 cases of PJK, 1 case of PJL, 2 cases of ST, and 2 implant failures were observed in VCR group. The SRS-Schwab Grade 4 osteotomy group had 1 neurophysiological monitoring event, 1 neurological injury, 4 cases of PJK, 2 cases of ST, and 1 implant failure. The complication rates between the groups were not statistically different ( P>0.05). Both groups showed significant improvements in the self-image domain of the SRS-22 postoperatively and at the final follow-up ( P<0.05). In the function domain, both groups also demonstrated significant improvement at the final follow-up ( P<0.05), while the SRS-Schwab group showed earlier improvement at 3 months postoperatively ( P<0.05). Conclusions:SRS-Schwab grade 4 osteotomy provides comparable correction of segmental kyphosis to VCR but offers the advantages of significantly reduced blood loss and shorter operative time. Both surgical techniques effectively improve patients' quality of life.

Objective:To analyze the selection of internal fixation methods, surgical outcomes, and complications in patients with Neurofibromatosis Type 1 (NF1) accompanied by dystrophic lumbosacral deformities, and to evaluate the indications for pelvic fixation.Methods:A retrospective analysis was conducted on 21 patients with NF1 and associated dystrophic lumbosacral malformations (L 4 to sacrum) who underwent spinal deformity correction surgery at Nanjing Drum Tower Hospital from January 2009 to November 2022. The cohort included 11 males and 10 females, with a mean surgical age of 15.4±4.7 years (range, 7-24 years). Patients were divided into two groups based on whether pelvic fixation was performed: 10 patients in the non-pelvic fixation group (NP group) and 11 in the pelvic fixation group (P group), where fixation involved second sacral alar-iliac (S 2AI) screws or iliac screws. Radiographic parameters, including the Cobb angle of the lumbosacral fractional curve, main curve, and focal kyphosis, were compared preoperatively, postoperatively, and at the last follow-up. Results:The NP group had a significantly lower mean age (13.2±4.9 years) compared to the P group (17.5±3.5 years; t=2.287, P=0.034). Spinal instability (rotational subluxation or spondylolisthesis) due to dystrophic changes was observed in 2 patients in the NP group and 8 in the P group, a statistically significant difference (χ 2=5.838, P=0.030). In the P group, five patients underwent unilateral fixation and six underwent bilateral fixation. Implant types included 2 cases with iliac screws, 1 case with iliac screws plus S 2AI, and 8 cases with S 2AI screws alone. The utilization rate of hooks was significantly higher in the NP group (12.6%±11.5%) compared to the P group (3.5%±6.9%; t=2.230, P=0.038). The preoperative Cobb angle of the lumbosacral fractional curve was significantly smaller in the NP group (13.8°±9.0°) than in the P group (25.5°±13.9°; t=2.228, P=0.039). Postoperatively, the angles were corrected to 6.3°±6.1° and 6.4°±5.3°, respectively ( t=0.901, P=0.969), with correction rates of 57.3%±13.6% and 74.1%±17.8% ( t=2.369, P=0.029). At final follow-up, the angles remained stable (6.6°±6.6° vs. 6.3°±4.8°; t=0.116, P=0.909). For the main curve, preoperative Cobb angles were 52.5°±15.1° (NP) and 61.1°±16.9° (P; t=1.200, P=0.246), corrected to 31.3°±13.8° and 28.0°±8.4°, respectively ( t=0.646, P=0.526). Correction rates were 41.3%±13.0% in the NP group and 53.2%±11.6% in the P group ( t=2.206, P=0.037). At the final follow-up, these values were 32.4°±14.2° and 31.7°±10.3° ( t=0.133, P=0.896). Focal kyphosis, seen in 9 patients, was corrected from 19.7°±10.9° preoperatively to -13.6°±9.5° postoperatively, and remained at -14.1°±9.6° at the final follow-up ( F=33.547, P<0.001). Multi-rod systems were used in 6 cases (NP group) and 7 cases (P group), with no significant difference (χ 2=0.153, P=0.926). Two patients in the NP group developed coronal decompensation three years postoperatively, and one required revision surgery. In the P group, rod breakage occurred in 3 patients, two of whom underwent revision. Conclusions:Dystrophic rotational subluxation or spondylolisthesis of the lumbosacral spine is a primary indication for pelvic fixation in patients with NF1-associated deformities. However, complications related to internal fixation remain common. The combined use of a multi-rod screw-hook hybrid system, particularly when extending across the lumbosacral region, may reduce the risk of instrumentation failure.

Objective:To evaluate the relationship between postoperative changes in femoral head coverage (FHC) after S 2-Alar-Iliac (S 2AI) screw fixation and the development of sagittal imbalance during follow-up in patients with adult spinal deformity (ASD), providing insights for clinical assessment and treatment strategies. Methods:A consecutive cohort of 98 ASD patients who underwent S2AI fixation between September 2019 and September 2021 was retrospectively analyzed. Patients were divided into two groups based on changes in femoral head coverage (ΔFHC): the FHC-C group (upper quartile ΔFHC, 25 cases) and the FHC-NC group (lower quartile ΔFHC, 24 cases). Additionally, patients were classified into proximal junctional kyphosis (PJK) and non-PJK groups based on their clinical outcomes at the last follow-up. Standing full-spine anteroposterior and lateral X-rays were taken preoperatively, postoperatively, and at the two-year follow-up to measure and document the following spinal parameters: Cobb angle, proximal lumbar lordosis (PLL), distal lumbar lordosis (DLL), lumbar lordosis (LL), lordosis distribution index (LDI), sagittal vertical axis (SVA), coronal balance distance (CBD), thoracic kyphosis (TK), T 1 pelvic angle (T 1PA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), PI-LL, and proximal junctional angle (PJA). Parameters related to hip joint coverage included: femoral head coverage (FHC), lateral center-edge angle (LCE angle), acetabular index (AI), Sharp angle, and extrusion index (EI). Comparisons of radiographic indicators between the two groups were performed at preoperative, postoperative, and final follow-up assessments. The visual analogue scale (VAS) was used to evaluate the hip pain and back pain. Results:At final follow-up, the incidence of PJK was significantly higher in the FHC-NC group [37.5% (9/24)] compared to the FHC-C group [16.0% (4/25)] (χ 2=3.952, P=0.042). Moreover, the increase in sagittal vertical axis (ΔSVA) was significantly greater in the FHC-NC group (35.9±44.7 mm vs. 14.6±31.8 mm, t=2.216, P=0.031). Patients with PJK had significantly higher preoperative T 1PA (36.8°±10.8° vs. 31.9°±18.4°, t=2.150, P=0.034) and lower immediate postoperative ΔFHC (1.7%±1.5% vs. 3.3%±2.5%, t=2.987, P=0.004), as well as lower changes in lateral center-edge angle during follow-up (0.3°±3.0° vs. 1.1°±8.9°, t=2.334, P=0.022). Pearson correlation analysis revealed significant negative correlations between postoperative ΔFHC and both ΔSVA ( r=-0.374, P=0.008) and proximal junctional angle changes (ΔPJA, r=-0.429, P=0.006). Additionally, increases in VAS leg pain scores correlated negatively with immediate postoperative FHC ( r=-0.314, P=0.025) and ΔFHC ( r=-0.298, P=0.031). Logistic regression indicated that immediate postoperative ΔFHC was a protective factor against PJK [ OR=0.722, 95% CI (0.541, 0.963), P=0.009), with a ROC-determined optimal ΔFHC cut-off of 3.90% (AUC=0.723, Youden index=0.847). Conclusions:Postoperative evaluation of femoral head coverage is clinically important for ASD patients undergoing S2AI screw fixation. A pre-to-post ΔFHC below 3.90% may indicate reduced hip compensation capacity, increasing risks for hip pain, sagittal imbalance progression, and PJK postoperatively.

Objective:To predict mechanical complications (MC) following spinal deformity surgery for adult spine deformity (ASD) using machine learning models, identify key risk factors, and develop a visualizable tool for individualized risk assessment.Methods:Clinical and radiological data from 525 patients with ASD who underwent surgery in our hospital between January 2017 and December 2021 were collected. Patients were randomly assigned to a training set (70%) and a test set (30%) for model development. The cohort included 88 males and 437 females, with a mean age of 42.2±18.1 years. Variables included demographic data, comorbidities, local and systemic radiological parameters, paraspinal muscle fat infiltration (FI), and vertebral bone quality (VBQ) scores. Multiple machine learning algorithms: Random Forest (RF), Gaussian Naive Bayes (GNB), Light GBM, Support Vector Machine (SVM), XGBoost (XGB), and Logistic Regression (LR) were trained and evaluated. Model performance was compared using the receiver operating characteristic curve (ROC) and precision-recall curve (PRC). SHAP (Shapley Additive Explanations) was used to rank risk factors, while LIME (Local Interpretable Model-Agnostic Explanations) was applied to visualize MC risk in individual cases.Results:Of the 525 patients, 135 (25.7%) developed postoperative MC. Among these, 80 (59.3%) experienced proximal junction kyphosis or failure (PJK/PJF), 7 (5.2%) had distal junction kyphosis or failure (DJK/DJF), 28 (20.7%) sustained rod fractures, and 29 (21.5%) showed significant loss of correction. In the validation cohort, the RF model achieved the highest area under the curve (AUC=0.80), followed by GNB (0.77), XGB (0.76), LR (0.74), LightGBM (0.73), and SVM (0.66). The RF model also demonstrated the best PRC value (0.58), highest sensitivity (0.65), and lowest Brier score (0.20). GNB, Light GBM, and LR models achieved the highest accuracy (0.78 each), while LightGBM exhibited the highest specificity (0.93). SHAP analysis identified higher preoperative VBQ scores, larger T 1 pelvic angle (TPA), and higher paraspinal muscle FI as the main risk factors for MC. Based on the RF model, a LIME-based tool was successfully constructed for individualized MC risk estimation. Conclusion:The RF model demonstrated the best overall predictive performance for MC. A machine learning-based prediction model has the potential to provide valuable guidance for surgical decision-making in ASD patients.