Many studies have reported positive surgical outcomes and decreased mortality after spine surgery in the elderly population, including patients between 85 and 90 years of age. Here, in addition to patient age, we investigated the influence of frailty on short and long-term mortality in octogenarians after lumbar surgery. We performed a retrospective analysis of 162 patients over 80 years of age who underwent posterior lumbar fusion or decompressive laminectomy between January 2011 and September 2016. We examined patient survival and modified frailty index (mFI) from medical records. By October 2019, 29 of 162 patients had expired (follow up period: 1-105 months). Three-month mortality was 1.9%, and one-year mortality was 4.9%. Frailty did not affect long-term survival at one year but was associated with 3-month mortality (p=0.024). There was no relationship in long-term survival according to frailty in patients 80 years of age or older, but a difference was identified in short-term mortality. When making a surgical decision for lumbar spine surgery in frail patients over 80 years of age, surgeons should pay attention to the short-term prognosis.

Objective: Although adult spinal deformity (ASD) surgery aims to restore and maintain alignment, proximal junctional kyphosis (PJK) may occur. While existing scoring systems predict PJK, they predominantly offer a generalized 3-tier risk classification, limiting their utility for nuanced treatment decisions. This study seeks to establish a personalized risk calculator for PJK, aiming to enhance treatment planning precision.Methods: Patient data for ASD were sourced from the Korean spinal deformity database. PJK was defined a proximal junctional angle (PJA) of ≥ 20° at the final follow-up, or an increase in PJA of ≥ 10° compared to the preoperative values. Multivariable analysis was performed to identify independent variables. Subsequently, 5 machine learning models were created to predict individualized PJK risk post-ASD surgery. The most efficacious model was deployed as an online and interactive calculator.Results: From a pool of 201 patients, 49 (24.4%) exhibited PJK during the follow-up period. Through multivariable analysis, postoperative PJA, body mass index, and deformity type emerged as independent predictors for PJK. When testing machine learning models using study results and previously reported variables as hyperparameters, the random forest model exhibited the highest accuracy, reaching 83%, with an area under the receiver operating characteristics curve of 0.76. This model has been launched as a freely accessible tool at: (https://snuspine.shinyapps.io/PJKafterASD/).Conclusion: An online calculator, founded on the random forest model, has been developed to gauge the risk of PJK following ASD surgery. This may be a useful clinical tool for surgeons, allowing them to better predict PJK probabilities and refine subsequent therapeutic strategies.

Objective: Spinal stenosis is a prevalent condition; however, the optimal surgical treatment for central lumbar stenosis remains controversial. This study compared the clinical outcomes and radiological parameters of 3 surgical methods: unilateral laminectomy bilateral decompression with unilateral biportal endoscopy (ULBD-UBE), conventional subtotal laminectomy (STL), and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).Methods: This retrospective study included 86 patients, divided into ULBD-UBE (n=34), STL (n=24), and MIS-TLIF (n=28) groups. We evaluated demographics and perioperative factors and assessed clinical outcomes using the visual analogue scale (VAS), Oswestry Disability Index (ODI), and neurogenic intermittent claudication (NIC). Radiological parameters assessed included lumbar lordosis, L4S1 Cobb angle (L4S1), T12S1 Cobb angle (T12S1), increased cross-sectional dural area (CSA), dynamic angulation (DA), dynamic slip (DS), and development of postoperative instability.Results: The ULBD-UBE group showed a significantly shorter hospital stay duration and operation time and reduced blood loss than the other groups (p<0.001). ULBD-UBE group showed a trend towards greater VAS and ODI improvement at 1 month and postoperative NIC symptom relief. Radiologically, MIS-TLIF group exhibited lower postoperative DA and DS (p<0.001), indicating higher postoperative stability. Postoperative instability was lower in the ULBD-UBE group (2.9%) than in the STL group (16.7%) and similar to the MIS-TLIF group (0.0%) (p=0.028). The CSA was highest in the MIS-TLIF group (295.5%) compared to that in the other groups (ULBD-UBE, 216.3%; STL, 245.2%) (p<0.001).Conclusion: Compared to other procedures, ULBD-UBE is a safe, effective, and viable surgical procedure for treating lumbar central stenosis.

Objective: To evaluate the impact of the K-line and canal-occupying ratio (COR) on surgical outcomes in patients with multilevel cervical ossification of the posterior longitudinal ligament (OPLL).Methods: Patients with cervical myelopathy due to multilevel OPLL who underwent decompression surgery (anterior or posterior) from 2013 to 2022, with 2-year minimum follow-up, were enrolled. Radiological evaluations included K-line, COR, OPLL type/level, and cervical parameters (C2 slope [C2S], T1 slope [T1S], K-line tilt). Clinical outcomes included Japanese Orthopaedic Association (JOA) score and neck-pain visual analogue scale. Patients were categorized by K-line status (+/-) and COR (<50% or ≥50%).Results: Among 575 patients, JOA recovery was significantly better in the K-line (+) and in low COR (<50%). In high COR (≥50%), K-line (-) was associated with poorer recovery. In low COR, outcomes were similar regardless of K-line. Anterior decompression with fusion (ADF) yielded the best outcomes. Laminoplasty (LP) was optimal for COR ≥50% and/or K-line (+), while laminectomy with fusion (LF) was better for COR ≥50% and K-line (-). In high COR, K-line was influenced by cervical alignment, C2S, and T1S, while in low COR, it was mainly affected by COR percentage.Conclusion: Combining K-line and COR is essential for surgical planning in multilevel OPLL. When COR is high, K-line plays a significant role in predicting neurological recovery. ADF led to superior recovery, whereas for patients with K-line (-) and high COR, LF offered better results than LP. Cervical parameters at high COR influence the K-line more.

Adjacent segment disease (ASD) is a prevalent complication following lumbar fusion surgery, representing a significant challenge in spinal surgery. This study aimed to assess the long-term outcomes of Nitinol spring rod semi-rigid fixation, a potential alternative to traditional rigid fixation, in reducing the incidence of ASD. This retrospective case study evaluated 89 patients who underwent lumbar or lumbosacral surgeries using a combination of Bioflex^® (a Nitinol spring rod dynamic stabilization system) and an interbody cage over 10 years of follow-up. The fusion status, adjacent segment disc height, mechanical complications, and re-operation rates were analyzed. The cohort had a median follow-up duration of 13.0 years. All patients achieved solid fusion at the final follow-up visit. One patient underwent revision surgery for clinical ASD (1.1%), and no patients required revision surgery due to mechanical problems. Radiological evidence of ASD was observed in 16.9% of the patients. This study’s findings suggest that semi-rigid fixation using Bioflex with an interbody cage is a possibly effective treatment strategy to prevent ASD. The technique potentially reduces the risk of ASD by allowing a degree of movement at the surgical site.

To investigate the radiographic characteristics of the uppermost instrumented vertebrae (UIV) and UIV+1 compression fractures that are predictive of revision surgery following long-segment spinal fixation. A total 27 patients who presented newly developed compression fracture at UIV, UIV+1 after long segment spinal fixation (minimum 5 vertebral bodies, lowest instrumented vertebra of L5 or distal) were reviewed retrospectively. Patients were divided into two groups according to following management : revisional surgery (group A, n=13) and conservative care (group B, n=14). Pre- and postoperative images, and images taken shortly before and after the occurrence of fracture were evaluated for radiologic characteristics. Despite similar degrees of surgical correction of deformity, the fate of the two groups with proximal junctional compression fractures differed. Immediately after the fracture, the decrement of adjacent disc height in group A (32.3±7.6 mm to 23.7±8.4 mm, Δ=8.5±6.9 mm) was greater than group B (31.0±13.9 mm to 30.1±15.5 mm, Δ=0.9±2.9 mm, p=0.003). Pre-operative magnetic resonance imaging indicated that group A patients have a higher grade of disc degeneration adjacent to fractured vertebrae compared to group B (modified Pfirrmann grade, group A : 6.10±0.99, group B : 4.08±0.90, p=0.004). Binary logistic regression analysis indicated that decrement of disc height was the only associated risk factor for future revision surgery (odds ratio, 1.891; 95% confidence interval, 1.121-3.190; p=0.017). Proximal junctional vertebral compression fractures with greater early-stage decrement of adjacent disc height were associated with increased risk of future neurological deterioration and necessity of revision. The condition of adjacent disc degeneration should be considered regarding severity and revision rate of proximal junctional kyphosis/proximal junction failures.