Asian Spine Journal最新文献

Study design: Retrospective cross-sectional study.

Purpose: To investigate the size and local anatomy of the right and the left-sided oblique corridors between L1-L5 levels and identify the potential impact of increasing age and sex on corridor size.

Overview of literature: The oblique lumbar interbody fusion (OLIF) was introduced by Silvestre and his colleagues as a solution to the approach-related complications associated with anterior lumbar interbody fusion and lateral lumbar interbody fusion. Limited data were available describing the local anatomy and morphology of this approach.

Methods: Imaging data of 300 patients (150 males and 150 females) who underwent 1.5T magnetic resonance imaging (MRI) scans of the lumbar spine at Indian Spinal Injuries Centre, New Delhi, India between January 2023 and January 2024 were retrospectively reviewed. The cohort was stratified into six age groups (21-30, 31-40, 41-50, 51-60, 61-70, and >70 years) with 25 patients in each age group for both sexes. T2 weighted axial MRI images were analyzed from the L1-L5 level at the mid-disc level to calculate the corridor size. The local anatomical differences were recorded.

Results: At L1-L2, L2-L3, L3-L4, and L4-L5 levels, the mean corridor sizes in males were 17.48, 15.50, 13.41, and 9.32 mm on the left side, and 11.48, 7.12, 4.34, and 1.64 mm on the right side, respectively. The corresponding mean corridor sizes in females were 10.34, 12.94, 12.64, and 7.22 mm on the left side and 2.66, 3.52, 3.69, and 1.64 mm on the right side, respectively. For both sides, the corridor size was significantly affected by sex, increased with age, and decreased at the lower lumbar disc levels.

Conclusions: A left-sided OLIF approach is more feasible for both sexes. The right-sided approach is less likely to be performed effectively.

Study design: A retrospective comparative study.

Purpose: To compare the characteristics of perioperative complications in patients aged ≥85 years with those of younger patients undergoing similar spine surgery and examine factors associated with perioperative complications and clinical outcomes among patients aged ≥85 years.

Overview of literature: The risk factors for perioperative complications and their effect on outcomes in patients aged ≥85 years remain unclear. Furthermore, no study has compared younger patients with similar surgeries and condition with those aged ≥85 years.

Methods: The study included patients aged ≥65 years who underwent spinal surgeries. The patients aged ≥85, 75-84, and 65-74 years were categorized into the super-old, old, and pre-old groups, respectively. The differences in perioperative age-related complications were compared among the three groups while matching for surgical procedures and general conditions (study 1). Furthermore, preoperative and intraoperative factors were examined for perioperative complications in the super-old group (study 2). Complications were categorized into surgical site and systemic complications.

Results: The analysis included 44 patients from each group. In study 1, the total complication rates were 40.9%, 25%, and 18.2% of the super-old, old, and pre-old groups, respectively. Differences in complication rates were observed between the super-old and pre-old groups (p=0.011). In study 2, 58 patients from the super-old group were analyzed. Surgical site complications were significantly associated with longer surgical duration (p=0.02) and more estimated blood loss (p=0.003). Systemic complications were significantly associated with previous cerebrovascular disease (p=0.014), preoperative motor deficit (p=0.023), and emergency case (p=0.006) and negatively associated with diabetes mellitus (p=0.048).

Conclusions: Perioperative complications increased with advancing age in the super-old, old, and pre-old groups. The complication type is associated with specific background factors; therefore, determining them may help prevent perioperative complications.

Study design: A retrospective study.

Purpose: To identify factors involved in surgical site infections (SSIs) after spinal instrumentation surgery performed at a single institution.

Overview of literature: SSIs after spinal instrumentation surgery are a serious complication. Despite reports on risk factors for SSIs in spine surgery, limited studies are related to spinal instrumentation surgery.

Methods: In total, 828 patients (338 males and 490 females; mean age, 65.0 years) who underwent spinal instrumentation surgery from 2013 to 2021 in Kyorin University School of Medicinewere retrospectively investigated. Patients were divided into the SSI (group I) and non-SSI (group N) groups. Patient characteristics, comorbidity, laboratory, and surgical factors were investigated. Univariate analysis was performed for each item, and multivariate logistic regression analysis was performed for items with significant differences.

Results: Fifteen patients (1.85%) had SSIs. Univariate analysis revealed significant differences between groups I and N in history of steroid use, serum albumin, C-reactive protein, number of fixed vertebrae, and perioperative blood transfusion. Multivariate logistic regression analysis showed that a history of steroid use (odds ratio [OR], 5.38; 95% confidence interval [CI], 1.41-20.49; p=0.014), serum albumin (OR, 0.34; 95% CI, 0.13-0.84; p=0.020), and perioperative blood transfusion (OR, 5.85; 95% CI, 1.46-23.50; p=0.013) were independent risk factors for SSIs.

Conclusions: The results of this study indicate that preoperative nutritional intervention, appropriate management of anemia, and intraoperative and postoperative bleeding control may decrease the incidence of SSIs. However, this study has several limitations, including its retrospective design, analysis of a few SSI cases, and inclusion of various surgical approaches and disease types. Future studies that address these limitations are desirable.

Study design: Basic study.

Purpose: This study aimed to utilize finite element (FE) analysis and design of experiment (DoE) techniques to propose and optimize a novel pedicle screw design and compare its pull-out force with that of a control device.

Overview of literature: Pedicle screw-based fixation is the gold-standard treatment for spine diseases, particularly in fusion procedures. However, pedicle screw loosening and breakage still occur in osteoporotic and non-osteoporotic patients. This research investigates screw design modifications to enhance screw-bone interface strength and reduce the likelihood of loosening.

Methods: We conceptualized a novel pedicle screw considering vertebral bone morphology and strength differences. A validated FE model was developed and used in conjunction with DoE to determine the screw՚s optimum geometrical parameters. The FE model was validated through simulation and laboratory experiments using the control device. The optimized thread profiles for cortical bone and cancellous bone were determined, with pull-out force as the primary factor for screw design evaluation.

Results: FE analysis results for the control device closely matched experimental results, with less than 5% difference. The chosen unique pitch/depth ratio showed maximum pull-out force for cortical bone, while DoE enabled the optimization of design parameters for cancellous bone. The optimized pedicle screw exhibited a 15% increase in pull-out force compared to the control device.

Conclusions: The study proposes a novel pedicle screw design with better pull-out strength than the control device. Combining FE analysis with DoE is an effective approach for screw design optimization, reducing the need for extensive prototyping tests. A two-variable analysis suffices for optimizing cortical bone design parameters, while a multi-variable analysis is more effective for optimizing cancellous bone design parameters.

Study design: Retrospective cohort study.

Purpose: This study aimed to demonstrate the advantages of preservation of the lumbosacral segment (LSS) in adult spinal deformity (ASD) surgery.

Overview of literature: Sacroiliac foundation enables sufficient restoration in ASD surgery; however, it could result in poor mobility. Thus, whether LSS provides better activities is still unknown.

Methods: Among 399 patients who underwent ASD surgery, 62 (≥5 levels fused, >2-year follow-up) underwent fusion from T9-10 to L5 (group L, n=21) or to S2-alar-iliac (group S, n=41). Spinal alignments, Scoliosis Research Society (SRS)-22 scores, performance of activities (clipping toenail, wiping buttock, and wearing socks), proximal and distal junctional failure (PJF+DJF), rod fractures (RFs), and overall revision rates (RRs) were compared between the groups.

Results: Group L included younger patients and had longer follow-ups when compared with group S. Although the preoperative pelvic incidence and SRS sagittal modifiers were better in group L, postoperative spinal restorations were nonpathological in both groups. Both groups showed similar deformity progression at the 2-year follow-up; however, group L had lower SRS-22 pain scores. Although "wiping buttocks" did not differ between the groups, the performance of "clipping toenails" and "wearing socks" was poorer in group S at 2 years (possible, group S; 40% vs. group L; 85%-90%). The RRs did not differ between the groups; however, the PJF+DJF rate was higher in group L. DJF was not observed in group S, but occurrence of RFs was noted.

Conclusions: Although poorer SRS-22 pain scores might be related to lumbosacral mobility, sufficient restoration, equivalent deformity progression, and similar RRs with better activity imply that lumbosacral preservation should be considered in younger patients with moderate deformities.

Study design: Retrospective cohort study.

Purpose: To determine the incidence and success of three-column osteotomies (3COs) performed in primary and revision adult spine deformity (ASD) corrective surgeries.

Overview of literature: 3COs are often required to correct severe, rigid ASD presentations. However, controversy remains on the utility of 3COs, particularly in primary surgery.

Methods: Patients ASD having 2-year data were included and divided into 3CO and non-3CO (remaining ASD cohort) groups. For the subanalysis, patients were stratified based on whether they were undergoing primary (P3CO) or revision (R3CO) surgery. Multivariate analysis controlling for age, Charlson comorbidity index, body mass index, baseline pelvic incidence-lumbar lordosis, and fused levels evaluated the complication rates and radiographic and patient-reported outcomes between the 3CO and non-3CO groups.

Results: Of the 436 patients included, 20% had 3COs. 3COs were performed in 16% of P3COs and 51% of R3COs. Both 3CO groups had greater severity in deformity and disability at baseline; however, only R3COs improved more than non-3COs. Despite greater segmental correction, 3COs had much lower rates of aligning in the lumbar distribution index (LDI), higher mechanical complications, and more reoperations when performed below L3. When comparing P3COs and R3COs, baseline lumbopelvic and global alignments, as well as disability, were different. The R3CO group had greater clinical improvements and global correction (both p<0.04), although the P3CO group achieved alignment in LDI more often (odds ratio, 3.9; 95% confidence interval, 1.3-6.2; p=0.006). The P3CO group had more neurological complications (30% vs. 13%, p=0.042), whereas the R3CO tended to have higher mechanical complication rates (25% vs. 15%, p=0.2).

Conclusions: 3COs showed greater improvements in realignment while failing to demonstrate the same clinical improvement as primaries without a 3CO. Overall, when suitably indicated, a 3CO offers superior utility for achieving optimal realignment across primary and revision surgeries for ASD correction.

Study design: Retrospective cohort study.

Purpose: This study aimed to explore the morphometry of the Thai lumbar vertebrae.

Overview of literature: The cortical bone trajectory (CBT) is a novel approach for vertebral screw fixation aimed at addressing spinal instability associated with spinal disorders. The morphometry of the lumbar vertebrae is crucial in tailoring screw design for each CBT application, given the significant variations in optimal screw sizes, lengths, and angles among populations.

Methods: A total of 300 dried lumbar columns were used to measure the pedicle height (PH) and width (PW), length for cortical bone trajectory (LCT), cephalad screw angle (CSA), axial cortical bone trajectory angle (ACA), and possible cortical zones for the CBT.

Results: The following average values were calculated: PH in L1, 15.09±1.44 mm; PW in L5, 16.96±2.42 mm; LCT in L3, 35.75±2.61 mm; CSA in L1, 20.85°±2.30°; and ACA in L5, 21.83°±2.49°. Women generally had shorter PH and PW than men, with significant differences across lumbar levels. The LCT was significantly shorter in women and was notably different between the left and right sides. The CSA and ACA varied significantly between sexes and sides, with specific lumbar levels showing wider angles in one sex over the other. The most common cortical zones for screw tips were Z3 and Z10, with high incidences across all lumbar levels.

Conclusions: This study presents detailed lumbar vertebral morphometry data specific to the Thai population. The results are essential for CBT application in screw fixation procedures. This information will contribute to the production of optimally designed screws for Thai patients in the future.

Minimally invasive spine surgery (MISS) has revolutionized the treatment of spinal disorders over the past few decades. This review provides an in-depth analysis of MISS techniques, technologies, outcomes, and future directions. The evolution of MISS techniques-including tubular retractor systems, percutaneous pedicle screw fixation, minimally invasive transforaminal lumbar interbody fusion, lateral lumbar interbody fusion, and endoscopic spine surgery-has expanded the scope of treatable spinal pathologies while minimizing tissue trauma. Technological advancements such as intraoperative navigation, robotics, and augmented reality applications have enhanced precision and capabilities. Clinical evidence supports the efficacy and safety of MISS techniques for various spinal pathologies, demonstrating comparable or superior outcomes to traditional open approaches with reduced tissue trauma, blood loss, and hospital stays. Cost-effectiveness analyses also favor MISS over open techniques. Future directions in MISS include expanding indications, integrating artificial intelligence and machine learning, advancing tissue engineering and biologics, and refining robotic and augmented reality applications. As MISS continues to evolve, it is poised to play an increasingly important role in the treatment of spinal disorders, offering improved patient outcomes with reduced morbidity. However, ongoing rigorous evaluation of new techniques and technologies is crucial to balance potential benefits with associated risks and costs.

Study design: Biomechanical study.

Purpose: To investigate the mechanical characteristics of bone models created from medical images.

Overview of literature: Recent advancements in three-dimensional (3D) printing technology have affected its application in surgery. However, a notable gap exists in the analyses of how patient's dimorphism and variations in vertebral body anatomy influence the maximum insertional torque (MIT) and pullout strength (POS) of pedicle screws (PS) in osteoporotic vertebral bone models derived from medical images.

Methods: Male and female patients with computed tomography data were selected. Dimensions of the first thoracic (T1), fourth lumbar (L4), and fifth lumbar (L5) vertebrae were measured, and bone models consisting of the cancellous and cortical bones made from polyurethane foam were created. PS with diameters of 4.5 mm, 5.5 mm, and 6.5 mm were used. T1 PS were 25 mm long, and L4 and L5 PS were 40 mm long. The bone models were secured with cement, and the MIT was measured using a calibrated torque wrench. After MIT testing, the PS head was attached to the machine's crosshead. POS was then calculated at a crosshead speed of 5 mm/min until failure.

Results: The L4 and L5 were notably larger in female bone models, whereas the T1 vertebra was larger in male bone models. Consequently, the MIT and POS for L4 and L5 were higher in female bone models across all PS diameters than in male bone models. Conversely, the MIT for T1 was higher in male bone models across all PS; however, no significant differences were observed in the POS values for T1 between sexes.

Conclusions: The mechanical properties of the proposed bone models can vary based on the vertebral structure and size. For accurate 3D surgical and mechanical simulations in the creation of custom-made medical devices, bone models must be constructed from patientspecific medical images.

Study design: A retrospective cohort study.

Purpose: To investigate the sagittal plane configuration of the entire spine and its association with the risk of adjacent segment degeneration (ASD) after posterior lumbar interbody fusion (PLIF).

Overview of literature: Although PLIF has demonstrated satisfactory clinical outcomes, it is associated with ASD. However, the geometric mechanical changes that contribute to the occurrence of ASD are not well characterized.

Methods: Radiological parameters were extracted from the whole lateral radiographs. Patients were divided into two groups: the ASD group (segmental kyphosis of ≥10º, and/or a ≥50% loss of disc height, and/or ≥3 mm of anteroposterior translation) and the non-ASD group.

Results: All 112 included patients underwent PLIF for lumbar degenerative diseases. The minimum follow-up period was 2 years, with an average follow-up time of 63.6 months. Fifty-two patients (46.4%) were classified into the ASD group and of these, 13 required reoperation due to failure of conservative treatment. Patients with ASD exhibited significantly more caudal and posterior inflection vertebrae (IV), while the lumbar apical vertebra was significantly more caudal immediately after surgery. The IV position was identified as a significant risk factor for ASD, and the ASD incidence was significantly higher in the group where IV ≤5 (L1 vertebral body) than in the group where IV ≥5.5 (T12-L1 disc) (69.0% vs. 38.6%).

Conclusions: The IV position is a significant risk factor for ASD development. Although it is difficult to control intraoperative IV levels, we note a high risk of ASD in patients with IV lower than T12-L1.