Incidence, clinical features, and risk factors for acute pancreatitis following posterior instrumented fusion surgery for lumbar degenerative disease: a single-center, retrospective analysis of 20,929 patients.

PURPOSE: The aim of this study is to identify the incidence, clinical features, and risk factors for postoperative acute pancreatitis (PAP) after lumbar surgery. METHODS: We retrospectively analyzed patients who developed PAP after posterior lumbar fusion surgery. For each PAP patient, data were collected for four controls who underwent procedures in the same period and did not develop PAP. Statistical methods included univariate and multivariate analyses. RESULTS: Totally, 21 out of 20,929 patients were diagnosed with PAP (0.10%) after posterior lumbar fusion surgery. Patients with degenerative lumbar scoliosis were at higher risk of developing PAP (P < 0.05). With atypical clinical features, PAP occurred within 3 days (0-5) after surgery. PAP patients had significantly higher incidence of osteoporosis (47.6 vs. 22.6%, P = 0.030) and fusion of L1/2(42.9 vs. 4.3%, P = 0.010), lower albumin (42.2 ± 4.1 vs. 44.3 ± 3.2 g/L, P = 0.010), more fusion segments (median 4 vs. 3, P = 0.022), larger surgical invasiveness index (median 9 vs. 8, P = 0.007), longer operation duration (232 ± 109 vs. 185 ± 90 min, P = 0.041), greater estimated blood loss (median 600 vs. 400 mL, P = 0.025), lower intraoperative mean arterial pressure (87.2 ± 9.9 vs. 92.1 ± 8.8 mmHg, P = 0.024). Multivariate logistic regression analysis found three independent risk factors: fusion of L1/2, surgical invasiveness index > 8, and intraoperative mean arterial pressure < 90 mmHg. All patients were treated with conservative therapy and fully recovered after 8.1 (4-22) days. CONCLUSION: The incidence of PAP following posterior surgery for degenerative lumbar disease was 0.10%, and its clinical features were not typical. The fusion of L1/2, high surgical invasiveness index, and low intraoperative mean arterial pressure were independent risk factors for PAP after surgery for lumbar degenerative disease.

Learning Curve and Clinical Outcomes of Ultrasonic Osteotome-based En Bloc Laminectomy for Thoracic Ossification of the Ligamentum Flavum.

OBJECTIVE: Despite rapid advances in minimally invasive surgery, en bloc laminectomy remains the most common surgical approach for treating thoracic ossification of the ligamentum flavum (TOLF). However, the learning curve of this risky operation is rarely reported. Therefore, we aimed to describe and analyze the learning curve of ultrasonic osteotome-based en bloc laminectomy for TOLF. METHODS: Among 151 consecutive patients with TOLF who underwent en bloc laminectomy performed by one surgeon between January 2012 and December 2017, we retrospectively analyzed their demographic data, surgical parameters, and neurological function. Neurological outcome was evaluated with the modified Japanese Orthopaedic Association (mJOA) scale, and the Hirabayashi method was used to calculate the neurological recovery rate. The learning curve was assessed with logarithmic curve-fitting regression analysis. Univariate analysis methods were used for statistical analysis, including t-test, rank sum test, and chi-square test. RESULTS: A total of 50% of learning milestones could be reached in approximately 14 cases, and the asymptote in 76 cases. Therefore, 76 of the 151 enrolled patients were defined as the "early group," and the remaining 75 were delimitated as the "late group" for comparison. There was a significant intergroup difference in the corrected operative time (94.80 ± 27.77 vs 65.93 ± 15.67 min, P < 0.001) and the estimated blood loss (median 240 vs 400 mL, P < 0.001). The overall follow-up was 83.1 ± 18.5 months. The mJOA significantly increased from a median of 5 (IQR: 4-5) before the surgery to 10 (IQR: 9-10) at the last follow-up (P < 0.001). The overall complication rate was 37.1%, and no significant intergroup difference was found, except for the incidence of dural tears (31.6% vs 17.3%, p = 0.042). CONCLUSION: Initially, mastering the en bloc laminectomy technique using ultrasonic osteotome for TOLF treatment can be challenging, but the surgeon's experience improves as the operative time and blood loss decrease. Improved surgical experience reduced the risk of dural tears but was not associated with the overall complication rate or long-term neurological function. Despite the relatively long learning curve, en bloc laminectomy is a secure and valid technique for TOLF treatment.

Development and validation of a novel thoracic spinal stenosis surgical invasiveness index: a single-center study based on 989 patients.

BACKGROUND CONTEXT: Surgical invasiveness indices have been established for general spine surgery (surgical invasiveness index [SII]), spine deformity, and metastatic spine tumors; however, a specific index for thoracic spinal stenosis (TSS) has not been developed. PURPOSE: To develop and validate a novel invasiveness index, incorporating TSS-specific factors for open posterior TSS surgery, which may facilitate the prediction of operative duration and intraoperative blood loss, and the stratification of surgical risk. STUDY DESIGN: A retrospective observational study. PATIENT SAMPLE: Overall, 989 patients who underwent open posterior TSS surgeries at our institution during the past 5 years were included. OUTCOME MEASURES: The operation duration, estimated blood loss, transfusion status, major surgical complications, length of hospital stay, and medical expenses. METHODS: We retrospectively analyzed the data of 989 consecutive patients who underwent posterior surgery for TSS between March 2017 and February 2022. Among them, 70% (n=692) were randomly placed in a training cohort, and the remaining 30% (n=297) automatically constituted the validation cohort. Multivariate linear regression models of operative time and log-transformed estimated blood loss were created using TSS-specific factors. Beta coefficients derived from these models were used to construct a TSS invasiveness index (TII). The ability of the TII to predict surgical invasiveness was compared with that of the SII and assessed in a validation cohort. RESULTS: The TII was more strongly correlated with operative time and estimated blood loss (p<.05) and explained more variability in operative time and estimated blood loss than the SII (p<.05). The TII explained 64.2% of operative time and 34.6% of estimated blood loss variation, whereas the SII explained 38.7% and 22.5%, respectively. In further verification, the TII was more strongly associated with transfusion rate, drainage time, and length of hospital stay than SII (p<.05). CONCLUSIONS: By incorporating TSS-specific components, the newly developed TII more accurately predicts the invasiveness of open posterior TSS surgery than the previous index.

Thirty-day Unplanned Reoperations After Posterior Surgery for Thoracic Spinal Stenosis: A Single-center Study Based on 1948 Patients.

STUDY DESIGN: A retrospective study. OBJECTIVE: The purpose of this study is to identify the incidences, causes, and risk factors of 30-day unplanned reoperation of posterior surgery for thoracic spinal stenosis (TSS) based on 1948 patients in a single center. SUMMARY OF BACKGROUND DATA: Unplanned reoperation is suggested to be a useful quality indicator for spine surgery. However, the incidences, causes, and risk factors of 30-day unplanned reoperation in patients who underwent posterior spinal surgery for TSS have not been well-established. MATERIALS AND METHODS: We retrospectively analyzed the clinical data of patients who underwent posterior spinal surgery for TSS from January 2011 to December 2021. Statistical methods including univariate and multivariate analyses were performed to assess the incidences, causes, and risk factors. RESULTS: A total of 1948 patients who underwent posterior spinal surgery for TSS in our institution were reviewed, and 77 (3.95%) required unplanned reoperations within 30 days because of epidural hematoma (1.64%), wound-related complications (1.02%), inadequate decompression (0.41%), and implant malposition or failure (0.36%), neurological deficit (0.26%), and other causes (0.26%). After univariate analysis, seven clinical factors were associated with unplanned reoperation ( P <0.05). Multivariate logistic regression analysis showed that upper thoracic spine surgery ( P =0.010), thoracic kyphosis ≥45° ( P =0.039), and intraoperative dural injury ( P =0.047) were independent risk factors for 30-day unplanned reoperation of posterior surgery for TSS. CONCLUSIONS: The incidence of 30-day unplanned reoperations after posterior surgical treatment for TSS was 3.95%. The most common causes were epidural hematoma, wound-related complications, inadequate decompression, and implant malposition or failure. Upper thoracic spine surgery, thoracic kyphosis ≥45°, and intraoperative dural injury led to an increased risk of unplanned reoperation within 30 days after posterior spinal surgery for TSS. LEVEL OF EVIDENCE: 4.

Incidence, Risk Factors, and Outcomes of Symptomatic Bone Cement Displacement following Percutaneous Kyphoplasty for Osteoporotic Vertebral Compression Fracture: A Single Center Study.

STUDY DESIGN: Retrospective. BACKGROUND: Symptomatic bone cement displacement (BCD) is a rare complication following percutaneous kyphoplasty (PKP) interventions for osteoporotic vertebral compression fracture (OVCF). This study aimed to investigate the incidence and the outcomes of symptomatic BCD comprehensively and identify its risk factors. METHODS: The clinical data of patients treated with PKP for OVCF between January 2012 and December 2020 were extracted. Patients who developed BCD following PKP during follow-up were divided into the symptomatic and asymptomatic groups. Patients who did not develop BCD were assigned to the control group. Univariate and multiple logistic regression analyses were used to compare the three clinical groups' features to assess the independent risk factors for the symptomatic and asymptomatic groups. RESULTS: A total of 896 patients were enrolled. Twenty-one patients (2.3%) were identified as having symptomatic BCD following PKP for OVCF, and 35 (3.9%) developed asymptomatic BCD. Compared with the control group, the symptomatic and asymptomatic groups had a higher incidence of anterior leakage, intravertebral vacuum cleft (IVC) signs, and a lower cement distribution score. The symptomatic group had a lower relative cross-sectional area (rCSA) of the paraspinal muscle (PSM), higher PSM fatty degeneration, and higher kyphotic angle (at the last follow-up) than the asymptomatic and control groups. For outcomes, the symptomatic group had a higher VAS/ODI score and a higher incidence of new vertebral fractures compared with the asymptomatic and control groups. Anterior leakage (OR: 1.737, 95% CI: 1.215-3.300), the IVC sign (OR: 3.361, 95% CI: 1.605-13.036), the cement distribution score (OR: 0.476, 95% CI: 0.225-0.904), PSM rCSA (OR: 0.953, 95% CI: 0.917-0.992), and PSM fatty degeneration (OR: 1.061, 95% CI: 1.005-1.119) were identified as independent risk factors for the symptomatic group. Anterior leakage (OR: 1.839, 95% CI: 1.206-2.803), the IVC sign (OR: 2.936, 95% CI: 1.174-9.018), and cement distribution score (OR: 0.632, 95% CI: 0.295-0.858) were independent risk factors for the asymptomatic group. CONCLUSION: The incidence of symptomatic BCD is 2.3% in patients treated with PKP. Anterior leakage, the IVC sign, and the distribution score were independent risk factors for BCD, and paraspinal muscle degeneration was a specific risk factor for symptomatic BCD. Symptomatic BCD can lead to poor outcomes.