Over the past few decades, interest in minimally invasive spine surgery (MISS) has increased tremendously due to its core principle of minimizing approach-related injury while providing outcomes similar to traditional open spine procedures. With technical and technological advancements, MISS has expanded its utility not only to simple spinal stenosis, but also to complex spinal pathologies such as metastasis, trauma, or adult spinal deformity. In this article, we review the techniques and technology in MISS and discuss the indications, benefits, and limitations of MISS.

Oblique lumbar interbody fusion (OLIF) offers indirect decompression of stenotic lesions of the spinal canal and foramen through immediate disc height restoration. Only a few studies have reported the effect of cage position and associated intraoperatively modifiable factors for successful immediate indirect decompression following OLIF surgery. This study aimed to investigate the intraoperatively modifiable factors for successful radiological outcomes of OLIF. This study included 46 patients with 80 surgical levels who underwent OLIF without direct posterior decompression. Preoperative and postoperative radiological parameters were evaluated and intraoperatively modifiable radiologic parameters for successful immediate radiologic decompression on magnetic resonance image (MRI) were determined. Radiologic parameters were preoperative and postoperative radiological parameters including anterior disc height (ADH), posterior disc height (PDH) lumbar lordotic angle (LLA), segmental lordotic angle (SLA), foraminal height (FH), cage position, cross-sectional area (CSA) of the thecal sac, cross-sectional foraminal area (CSF), facet distance (FD) All radiologic outcomes significantly improved. Comparing preoperative and postoperative values, mean CSA increased from 99.63±40.21 mm² to 125.02±45.90 mm² (p<.0001), and mean left CSF increased from 44.54±12.90 mm² to 69.91±10.80 mm² (p<.0001). FD also increased from 1.40±0.44 to 1.92±0.71 mm (p<.0001). FH increased from 16.31±3.3 to 18.84±3.47 mm (p<.0001). ADH and PDH also significantly increased (p<.0001). Immediate postoperative CSF and FH improvement rate (%) were significantly correlated with posterior disc height restoration rate (%) (p=.0443, and p=.0234, respectively). In addition, the patients with a cage positioned in the middle of the vertebral body experienced a greater FH improvement rate (%) compared to the patients with a cage positioned anteriorly. Finally, Visual analogue scale (VAS) for leg pain was improved immediately. OLIF provided satisfactory immediate indirect decompression in central and foraminal spinal stenosis. Moreover, intraoperative surgical technique for successful radiologic CSF and FH improvement included restoration of the PDH and placement of the cage in the middle.

Background: Hip fracture is a major public health problem worldwide and being underweight is a risk factor for fractures. Few studies have investigated the association between being underweight and hip fracture in the general population. The present study investigated the incidence of hip fracture in a large population cohort based on detailed information about the degree of underweight.Methods: A nationwide retrospective cohort study of adults ≥40 years of age included 962,533 subjects who were not overweight or obese in 2009. The incidence and risk of hip fracture occurring between 2010 and 2018 was assessed based on the degree of underweight. Based on body mass index (BMI), the study population was categorized into normal (18.50–22.99 kg/m²), mild (17.00–18.49 kg/m²), moderate (16.00–16.99 kg/m²), and severe underweight (<16.00 kg/m²) groups. Cox proportional hazards analyses were performed to calculate the hazard ratio (HR) for the hip fracture based on the degree of underweight in reference to the normal weight.Results: Compared with subjects who were normal weight, those who were classified as mild underweight (1.03/1000 person‐years (PY) increase in incidence rate (IR); adjusted HR (aHR) 1.61; 95% confidence interval (CI) 1.48–1.76), moderate underweight (2.04/1000 PY increase in IR; aHR 1.85; 95% CI 1.65–2.08), or severe underweight (4.58/1000 PY increase in IR; aHR 2.33; 95% CI 2.03–2.66) were at significantly increased risk of hip fracture.Conclusions: The severity of underweight was significantly associated with risk of hip fracture. The subdivision of underweight helps to estimate fracture risk more accurately.

A CaO-SiO₂-P₂O₅-B₂O₃ bioactive glass-ceramic (BGS-7) spacer provides high mechanical stability, produces a chemical bond to the adjacent endplate, and facilitates fusion after spine surgery. This prospective, randomized, single-blind, non-inferiority trial aimed to evaluate the radiographic outcomes and clinical efficacy of anterior cervical discectomy and fusion (ACDF) using a BGS-7 spacer for treating cervical degenerative disorders. Thirty-six patients underwent ACDF using a BGS-7 spacer (Group N), and 40 patients underwent ACDF using polyetheretherketone (PEEK) cages filled with a mixture of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) for the treatment of cervical degenerative disorders. The spinal fusion rate was assessed 12 months postoperatively using three-dimensional computed tomography (CT) and dynamic radiographs. Clinical outcomes included patient-reported outcome measures, visual analog scale scores for neck and arm pain, and scores from the neck disability index (NDI), European Quality of Life-5 Dimensions (EQ-5D), and 12-item Short Form Survey (SF-12v2). All participants were randomly assigned to undergo ACDF using either a BGS-7 spacer or PEEK cage filled with HA and β-TCP. The primary outcome was the fusion rate on CT scan image at 12 months after ACDF surgery based on a per-protocol strategy. Clinical outcomes and adverse events were also assessed. The 12-month fusion rates for the BGS-7 and PEEK groups based on CT scans were 81.8% and 74.4%, respectively, while those based on dynamic radiographs were 78.1% and 73.7%, respectively, with no significant difference between the groups. There were no significant differences in the clinical outcomes between the two groups. Neck pain, arm pain, NDI, EQ-5D, and SF-12v2 scores significantly improved postoperatively, with no significant differences between the groups. No adverse events were observed in either group. In ACDF surgery, the BGS-7 spacer showed similar fusion rates and clinical outcomes as PEEK cages filled with HA and β-TCP.

Being underweight is associated with a high risk of hip fracture. However, the impact of change in underweight status on the risk of hip fracture is unknown. This study is performed to investigate the relationship between change in underweight status and risk of hip fracture. This study included 1,713,225 subjects aged ≥40 years who underwent two consecutive national health screenings between 2007 and 2009. We prospectively assessed the risk of hip fracture between 2010 and 2018 according to changes in underweight status. We divided the participants into four groups according to the change in underweight status: consistent non-underweight (non-underweight to non-underweight), became non-underweight (underweight to non-underweight), became underweight (non-underweight to underweight), and consistent underweight (underweight to underweight). Compared with the consistent non-underweight group, the became non-underweight (0.74/1000 person years (PY) increase in incidence rate (IR); adjusted hazard ratio (HR) 1.72; 95% confidence interval (CI) 1.42–2.07), became underweight (1.71/1000 PY increase in IR; adjusted HR 2.22; 95% CI 1.96–2.53), and consistent underweight (1.3/1000 PY increase in IR; adjusted HR 2.18; 95% CI 1.89–2.53) groups had a significantly increased risk of hip fracture (p < 0.001). Change in underweight status was significantly associated with a risk of hip fracture.

Study Design: Cadaveric experimental study.Purpose: To evaluate the feasibility and accuracy of pedicle screw placement using a custom-developed augmented reality-assisted pedicle screw fixation (ARPSF) system in a porcine spine model. Overview of Literature: Conventional pedicle screw placement techniques face limitations including potential inaccuracy, radiation exposure, and workflow disruption. Augmented reality technology can overlay virtual surgical planning directly onto the operative field while maintaining the surgeon’s focus on the patient.Methods: Five porcine cadaveric lumbar spines were used in this study. A custom-developed head-mounted display system with optical tracking projected three-dimensional reconstructed spine models and planned screw trajectories into the surgeon’s field of view. A single experienced spine surgeon placed 50 pedicle screws (4.5 mm diameter). Registration was performed using a point-pair matching technique with fifteen anatomical landmarks. Accuracy was assessed via postoperative computed tomography scan, measuring entry point deviation, trajectory deviation, and angular difference, and evaluated using the Gertzbein-Robbins classification.Results: Of the 50 pedicle screws placed, 47 (94%) achieved grade A accuracy with complete containment within the pedicle. The remaining three screws (6%) were classified as grade B, with minor breaches less than 2 mm. No unsafe placements (grades C–E) occurred. The mean entry point deviation was 0.55 mm (standard deviation [SD]=0.33 mm), and the mean deviation at the screw tip was 0.71 mm (SD=0.32 mm). The mean axial angular deviation was 2.04° (SD=0.58°). The average placement time was 2.2 minutes per screw.Conclusions: The custom-developed ARPSF system demonstrated high accuracy for pedicle screw placement in a porcine model, achieving submillimeter precision and minimal angular deviation. This experimental study shows the potential of augmented reality technology to enhance spine instrumentation precision.