Asian Spine Journal最新文献

Study design: Retrospective case series.

Purpose: To determine the prevalence of neural axis abnormalities (NAA) in patients with adolescent idiopathic scoliosis (AIS) undergoing deformity corrective surgery and evaluate factors that may predict the presence of underlying NAA in these patients.

Overview of literature: There is no clear consensus regarding the use of magnetic resonance imaging (MRI) to screen for potential NAA in patients with AIS. Various clinical and radiographic risk factors predicting underlying NAA have been suggested, but these remain controversial.

Methods: This study included 282 patients with presumed AIS who underwent preoperative MRI to exclude NAA between 2010 and 2020 in multiple centers. Spinopelvic parameters, including Cobb angle, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence, were measured on preoperative and postoperative radiographs. Additional clinical data were gathered on curve characteristics, symptomatic back pain, and abnormal preoperative neurological examinations.

Results: The median age was 14 years (range, 11-18 years). The cohort consisted of 49 males (17%), 217 patients (77%) of European ethnicity, 30 (10.6%) Māori, and 7 (2.5%) Pacific Islanders. Twenty-one patients (7.4%) had NAA, of which five required neurosurgical intervention. Among the NAA group, four were diagnosed with Chiari malformations, seven with syringomyelia, and four with both. The presence of NAA did not affect curve reduction with surgery. No significant association was found between NAA and any investigated variable.

Conclusions: Routine preoperative MRI is justifiable, as 7.4% of the cohort had NAA, with five patients requiring neurosurgical intervention, thereby altering operative management.

Study design: A retrospective cohort study and literature review.

Purpose: We analyzed the clinical characteristics of acute airway obstruction (AAO) after anterior cervical spine surgery (ACSS), evaluated the effectiveness of newly implemented preventive measures, and assessed whether extubation immediately after surgery is practical.

Overview of literature: AAO is a rare but potentially fatal complication after ACSS. Recent studies have focused on postoperative management strategies such as prolonged intubation in the intensive care unit; however, the feasibility and safety of immediate extubation have not been studied extensively. This study addressed this critical gap.

Methods: We retrospectively reviewed data from patients who underwent ACSS and then immediate extubation according to policy at our institution between April 2006 and January 2019. Patients were categorized into AAO and non-AAO groups according to whether postoperative airway compromise necessitated reintubation or hematoma evacuation. Statistical analyses identified surgery-related risk factors associated with AAO. These findings and a review of the literature prompted the implementation of 10 preventive measures in February 2019. We then analyzed outcomes from 156 subsequent cases of ACSS.

Results: AAO occurred in 7 (0.68%) of 1,036 patients. Significant risk factors included the number of fixed disc segments (p =0.031), instrumentation of a more cephalad upper vertebra (p =0.007), and use of a halo vest (p <0.001). Among 156 patients who underwent ACSS after preventive measures were implemented, no cases of AAO were observed, but statistical significance could not be determined because of the limited sample size.

Conclusions: We systematically examined AAO prevention strategies and the potential effectiveness of 10 preventive measures. Despite these preventive measures, AAO cannot be prevented entirely; thus, rigorous monitoring after extubation is essential. Although the trend toward prolonged intubation is increasing, our findings suggest that immediate extubation is suitable for most patients.

Study design: This single-center prospective study compared pin-mounted and pinless robot-assisted techniques for thoracolumbar pedicle screw placement.

Purpose: To evaluate the feasibility, accuracy, and safety of a novel pinless technique in comparison to the traditional pin-mounted method in thoracolumbar fusion surgery.

Overview of literature: Robot-assisted spine surgery has enhanced the precision of pedicle screw placement and reduced radiation exposure. While conventional pin-mounted techniques are effective, they can lead to hardware-related complications. Emerging evidence indicates that eliminating bone-mounted fixation could streamline the surgical workflow without compromising accuracy or safety.

Methods: A total of 750 consecutive patients who underwent robot-assisted thoracolumbar fusion were enrolled. Two groups were defined: 200 cases (890 screws) using the pin-mounted approach and 550 cases (3,034 screws) utilizing the pinless method. All procedures employed intraoperative computed tomography imaging and a standardized protocol with a table-mounted robotic system. Screw accuracy was assessed using the Gertzbein-Robbins grading system, with grades A and B classified as acceptable. Secondary parameters, including operative time, blood loss, and radiation exposure, were also recorded.

Results: The pin-mounted group achieved an overall pedicle screw accuracy of 99.55% compared to 99.40% in the pinless group (p >0.05). There were four breaches in the pin-mounted group and 18 breaches in the pinless group, all of which were revised intraoperatively, with no permanent neurovascular injuries or major complications reported. Blood loss and radiation exposure were similar between the groups.

Conclusions: The pinless robot-assisted pedicle screw placement technique demonstrates accuracy and safety comparable to the traditional pin-mounted method. By eliminating bone-mounted fixation, this approach simplifies the surgical workflow and reduces hardwarerelated complications, making it an effective alternative for thoracolumbar fusion surgery.

Unilateral biportal endoscopic surgery has received attention in the field of minimally invasive spinal surgery because of its various advantages, including minimized musculoligamentous injury, low postoperative pain, and faster recovery, compared with conventional open spinal surgery. Navigation system advancements have improved the precision of instrument placement and cage positioning, thereby facilitating the insertion of larger cages in the unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF). In this study, we demonstrated the safety and efficacy of lateral lumbar interbody fusion cage insertion in UBE-TLIF with the assistance of O-arm navigation.

Numerous techniques for C2 screw fixation have been recently reported. However, concerns remain regarding the risk of spinal cord or vertebral artery injury and inadequate biomechanical stability. To our knowledge, the specific transforaminal "in-out-in" screw fixation technique has not been previously reported. This study aimed to investigate the feasibility and preliminary clinical outcomes of a transforaminal "in-out-in" multi-cortical purchase screw for posterior C2 screw fixation. Between October 2022 and March 2023, 10 patients underwent posterior atlantoaxial internal fixation. All patients had severe hypoplasia of the C2 pedicle on at least one side, precluding the use of standard C2 pedicle screws. A transforaminal "in-out-in" screw was used as an alternative. No spinal cord injury, vascular injury, or other major complications were observed. No implant failure was noted at the final follow-up. In conclusion, the transforaminal "in-out-in" screw may achieve rigid three-column fixation with multiple cortical purchases. It represents a safe and effective alternative for posterior C2 fixation in patients with severely narrow C2 pedicles where traditional pedicle screw placement is not feasible.

C5 palsy (C5P) is a common, yet poorly understood complication of cervical decompressive surgery, causing substantial disability and impacting postoperative quality of life. Despite extensive research, the actual incidence and distribution of C5P across different cervical surgical approaches over the past decade remain unclear. A comprehensive literature search was conducted on October 15, 2024, across Google Scholar, Embase, PubMed, Web of Science, and Cochrane Library databases. Studies reporting C5P incidence following surgery for degenerative cervical conditions, published until 2024, were included, excluding reviews, opinions, letters, and non-English manuscripts. Ninety-seven articles were included, encompassing 21,231 patients undergoing decompressive cervical surgery for degenerative cervical myelopathy. The overall incidence of postoperative C5P was 7% (95% confidence interval [CI], 4%-10%). The highest incidence was observed with circumferential fusion (combined anterior-posterior approach) at 16% (95% CI, 8%-24%), while the lowest was with anterior cervical decompression and fusion at 4% (95% CI, 3%-5%). Incidence rates following laminoplasty and laminectomy and fusion were 6% (95% CI, 5%-7%) and 10% (95% CI, 8%-12%), respectively. Recovery time ranged from 20.9 to 35 weeks, with 19.1%-33% of patients experiencing residual weakness. Significant risk factors included male sex, preoperative intervertebral foraminal stenosis, ossified posterior longitudinal ligament, open-door laminoplasty, laminectomy (with/without fusion), and excessive spinal cord shift. The role of C4-5 foraminotomy remains contested. Our meta-analysis identifies the posterior surgical approach as a significant risk factor for C5P. Circumferential fusion poses the highest risk, while laminoplasty can reduce the risk compared to laminectomy (alone or with instrumented fusion).

Study design: Retrospective cohort study.

Purpose: This study aimed to (1) determine the incidence of lateral fusion following single-level oblique lateral interbody fusion (OLIF); (2) identify risk factors associated with the development of lateral fusion; (3) evaluate the effect of different fusion patterns on interbody cage subsidence rates; and (4) assess whether fusion patterns influence postoperative clinical outcomes.

Overview of literature: Fusion characteristics following OLIF differ from those seen in conventional transforaminal lumbar interbody fusion, most notably due to lateral fusion marked by extra-vertebral bony bridging (EVB). EVB may develop early postoperatively, suggesting a potential mechanism for early interbody fusion.

Methods: This retrospective cohort study included 153 single-level OLIF cases between January 2016 and December 2023. Postoperative computed tomography was used to classify patients into central fusion, lateral fusion, and non-fusion groups. Demographic, surgical, and radiographic parameters-including osteophyte grade, Hounsfield unit (HU) values, and cage positioning-were analyzed to identify factors affecting fusion. Cage subsidence and clinical outcomes (Oswestry Disability Index [ODI], Visual Analog Scale) were compared across groups.

Results: Lateral fusion occurred in 39.9% of cases, central in 56.9%, and non-fusion in 3.2%. Preoperative osteophytes and higher HU values were associated with lateral fusion (p<0.001). OLIF with standalone cages (OLIF-SA) had a significantly higher lateral fusion rate than OLIF with posterior screw fixation (OLIF-PS) (p=0.002). Smoking was a significant risk factor for non-fusion (p=0.005). No significant difference in cage subsidence was observed between central and lateral fusion, but non-fusion showed more severe subsidence. Clinical outcomes improved across fusion groups, though non-fusion cases had worse ODI scores at follow-up.

Conclusions: Lateral fusion is a distinct OLIF feature influenced by osteophytes, bone density, and fixation type. It does not negatively affect cage subsidence or outcomes, but solid fusion remains essential for recovery. These findings enhance understanding of OLIF fusion and may guide surgical planning.

Study design: This is a finite element study.

Purpose: To identify optimal trajectory, screw size, and screw shape using the finite element method.

Overview of literature: Patients with diffuse idiopathic skeletal hyperostosis often develop spinal instability after fractures due to ankylosis and bone fragility. We developed single or double endplate penetrating screw trajectory (SEPST/DEPST) to improve fixation strength by penetrating the vertebral endplate. However, the optimal screw length, diameter, and shape remain unclear.

Methods: Finite element models of T12 and L1 were constructed from computed tomography images of osteoporotic patients. Three analyses were conducted: (1) the impact of various screw diameters with DEPST, (2) a comparison of fixation strength between short DEPST (S-DEPST), which penetrates the posterolateral endplate, and conventional DEPST (C-DEPST), and (3) a comparison between conventional cancellous thread screws (CTS) and endplate screws (ETS). Pullout strength (POS) was measured in all analyses. Vertebral motion angle (VMA) of the lower instrumented vertebra (LIV) was measured in analyses (2) and (3), and the four-directional load test (4DLT) was performed in analysis (2).

Results: Larger screw diameters with DEPST correlated with elevated POS. S-DEPST demonstrated significantly better fixation strength with a POS 1.46 times higher than C-DEPST and 2.5 times higher than traditional trajectories. S-DEPST also demonstrated higher fixation in all directions in 4DLT. However, no significant difference was observed in the VMA of LIV. ETS demonstrated slightly higher fixation than CTS, but the difference was not statistically significant.

Conclusions: Fixation strength improved with larger screw diameters in DEPST. S-DEPST provided additional fixation due to rim penetration. ETS may offer a higher fixation strength and warrants further validation.

Trans-spinal motor evoked potentials (TsMEP) represent a novel intraoperative neuromonitoring technique designed to localize motor deficits when transcranial motor evoked potentials (TcMEP) are lost or unreliable. This technique involves direct electrical stimulation of the spinal cord through pedicle screws using a train of biphasic square-wave pulses, with myogenic responses recorded from limb muscles. In the presented case of kyphoscoliosis correction, TsMEP was employed after TcMEP signals failed to recover despite corrective measures. Stimulation at various vertebral levels allowed TsMEP to localize the level of motor pathway compromise, guiding targeted decompression. Unlike sensory-based methods such as dynamic spinal cord mapping, TsMEP directly evaluates motor tract integrity and provides real-time, segmental information without the need for epidural instrumentation. This technique also enabled monitoring of functional recovery through threshold changes, demonstrating its clinical utility. TsMEP holds promise as an intraoperative diagnostic and decision-making tool, especially in complex spinal surgeries with high neurological risk.