Introduction: The Hounsfield unit (HU) has been reported to correlate with lumbar bone mineral density; however, few studies have reported the cutoff values for diagnosing osteoporosis based on this correlation. Therefore, this study aims to determine the HU cutoff value for diagnosing osteoporosis.

Methods: We included 114 patients who had preoperative lumbar computed tomography (CT) and dual-energy x-ray absorptiometry (DXA) measurements of the lumbar spine and femoral neck within three months before surgery from 2019 to 2024.

Results: The correlation coefficient between the L1-L4 HU values and the lowest young adult mean (YAM) was r = 0.608 (P < 0.001). The regression line from the relationship between the lowest YAM and L1-4 HU was as follows: lowest YAM: L1-4 HU = −4.25+1.57 × lowest YAM. The HU value for YAM (70%) was 105.7.

Conclusions: HU measurement via CT may be a useful alternative diagnostic tool for preoperative evaluation of lumbar degenerative diseases.

Introduction: Adult spinal deformity (ASD) is a condition characterized by complex three-dimensional spinal deformities that adversely affect the quality of life (QOL) in older adults. Current assessments for ASD rely primarily on standing X-ray imaging. However, this method presents challenges, such as radiation exposure and limited reproducibility due to posture variability.

This study aims to evaluate the utility of artificial intelligence (AI)-based pose estimation using RGB images, which refer to images where each pixel is defined by the intensity of red, green, and blue colors, as a non-invasive alternative to traditional radiographic assessments in patients with ASD.

Methods: A total of 23 patients with ASD underwent simultaneous standing full-spine X-ray and full-length lower limb X-ray imaging, along with RGB image capture. Using pose estimation AI, 17 anatomical key points were identified, and specific pose estimation parameters were defined. Correlations between these AI-derived parameters and those obtained from X-ray measurements were then analyzed.

Results: Significant correlations were observed between the pose estimation parameters and X-ray parameters. Specifically, in the coronal plane, shoulder balance, trunk tilt, and knee varus/valgus showed significant correlations, while in the sagittal plane, trunk tilt and knee flexion/extension parameters showed significant correlations. These results suggest that pose estimation AI, using RGB images, may serve as a viable, non-invasive alternative for assessing postural alignment in ASD patients.

Conclusions: The AI-driven pose estimation method used in this study demonstrates the potential to facilitate non-invasive and straightforward postural assessment for patients with ASD, even when clothed. These findings are promising for clinical applications, enabling more frequent assessments without the associated risks of radiation exposure. Further studies involving larger patient cohorts are recommended to improve the accuracy and reliability of this technology for broader clinical use.

Introduction: Manual muscle testing (MMT) is widely used to assess muscle strength. However, in lumbar spine disorders with L4 nerve root impairment, there are cases where patients experience giving way and difficulty in performing daily activities despite having quadriceps muscle strength rated as MMT5. This raises questions about the validity of assessing muscle weakness solely with MMT when considering surgical indications. In this study, we assessed subjective symptoms obtained through interviews, quadriceps strength assessed by MMT, and knee extension strength measured with a handheld dynamometer, to evaluate the validity of strength assessment by MMT.

Methods: Between July and September 2023, among 233 patients scheduled for surgery due to lumbar spine disorders, 82 patients were included based on the inclusion criteria. An interview was conducted, and the patients were classified into two groups: the giving-way group (Group G) and the no-giving-way group (Group C). For preoperative evaluation, knee extension strength was measured in both groups, and the affected/unaffected ratio was calculated.

Results: There were 16 cases in Group G and 66 cases in Group C. The affected/unaffected ratio of knee extension strength was 77.8% in Group G and 90.7% in Group C, indicating a higher asymmetry in Group G.

Conclusions: Approximately 20% of patients reported experiencing giving way and showed left-right differences in knee extension strength, even with a quadriceps MMT5. This suggests that quadriceps strength assessment by MMT may lack accuracy and additional patient interviews are also necessary.

Introduction: The aim of this study was to evaluate the Hounsfield unit (HU) of vertebrae in patients with lumbar pyogenic spondylitis.

Methods: Sixty-five vertebrae of 32 patients with lumbar pyogenic spondylitis were included in this study. The HUs of vertebral bodies, pedicles, and pedicle screw sites (PSS) were measured using computed tomography, and the values were compared between infected vertebrae (Group I) and non-infected vertebrae (Group NI). Additionally, the HUs of the infected vertebrae were analyzed according to the stages of Griffiths classification. Patients who required surgical intervention were examined for the incidence of pedicle screw (PS) loosening within 6 months after surgery.

Results: The HU was significantly higher in Group I across all sites (p < 0.001). Furthermore, the HU of infected vertebrae was significantly higher in the vertebral bodies and PSS as the Griffiths classification stage progressed (p < 0.001). In 6 patients who underwent surgical treatment, 12 PSs were inserted into the infected vertebrae. PS loosening occurred in 2 patients and involved 4 vertebrae, but no other adverse events occurred.

Conclusions: Insertion of PSs in the infected vertebrae may be an effective surgical option to shorten the range of fixation.

Introduction: The accuracy of pedicle screw placement with a patient-specific guide and the associated intraoperative radiation exposure were examined.

Methods: In total, 17 patients had scoliosis surgery with pedicle screw insertion facilitated by a patient-specific guide. The accuracy of screw insertion was evaluated using the Gertzbein scale. The intraoperative irradiation dose and duration were examined to assess intraoperative radiation exposure.

Results: Among the 17 patients, seven were diagnosed with adolescent idiopathic scoliosis, four with syndromic scoliosis, five with residual scoliosis, and one with congenital scoliosis. There were 12 female and 5 male patients, with a mean age of 17.1±4.1 years. A total of 295 pedicle screws were inserted, with 241 in the thoracic vertebrae and 54 in the lumbar vertebrae. According to the Gertzbein scale, 99.0% were within the safe zone. The mean irradiation dose was 30.4±20.5 mGy, and the mean irradiation duration was 4.9±3.4 minutes.

Conclusions: The use of a patient-specific guide to insert pedicle screws in scoliosis surgery is a useful option in terms of high screw insertion accuracy and reduced radiation exposure.

Introduction: In this study, we conducted a multicenter prospective study of osteoporotic vertebral fracture (OVF)-induced neurological impairments to clarify their epidemiological characteristics.

Methods: This study investigated 108 cases treated for neurological impairments resulting from OVF. We analyzed the vertebral level of OVF, location of the stenosis, presence of a traumatic event, pathology of neurological impairment, and presence of delayed neurological deficits.

Results: The findings of the study indicates that, neurological impairments due to OVF were more common at the middle and lower levels of the lumbar spine, not in the thoracolumbar junction. In addition, more than 1/3 of all cases had no traumatic event and foraminal stenosis. Furthermore, more than half of the cases had delayed neurological deficits caused by OVF.

Conclusions: The present study revealed that neurological impairments associated with OVF were more frequent in the middle and lower lumbar spine. Foraminal stenosis due to OVF causing neurological impairments was not uncommon. In addition, cases with no traumatic event and delayed neurological deficits were not rare. Recognition of the clinical characteristics will enable appropriate diagnosis and treatment of neurological impairments associated with OVF.

Introduction: Biportal Endoscopic Spinal Surgery (UBE/BESS) is gaining attention as a minimally invasive surgical technique with high versatility. This study aimed to evaluate postoperative outcomes and complications of UBE/BESS.

Methods: A total of 320 patients who underwent UBE/BESS for lumbar disc herniation or lumbar spinal stenosis at our institution between April 2019 and July 2023 were retrospectively analyzed. Postoperative outcomes were assessed using the Visual Analog Scale (VAS) and the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) scores. Intraoperative and postoperative complications were also evaluated.

Results: Among 136 patients with lumbar disc herniation, VAS scores improved significantly for low back pain (55±30 to 12±17) and leg pain (74±23 to 10±15). JOABPEQ scores showed improvement across all domains. Similarly, in 184 patients with lumbar spinal stenosis, VAS scores for leg pain improved significantly (74±23 to 10±15), and JOABPEQ scores improved significantly in all domains. Intraoperative complications included one case of open conversion and six cases of dural tear, while postoperative complications included three cases of epidural hematoma, three cases of inferior articular process fracture, and one case of early recurrent herniation.

Conclusions: UBE/BESS is a safe and effective surgical technique with favorable postoperative outcomes. However, attention is needed to address complications specific to procedures performed under continuous irrigation.

Introduction: This study investigated the clinical outcomes and bone-related complications of single-level Posterior Lumbar Interbody Fusion (PLIF) in patients with low vertebral Hounsfield Unit (HU) values.

Methods: The study included 99 female patients aged 75 years or older who underwent single-level PLIF and were followed up for at least one year. The mean age was 78 years, with an average follow-up period of 6 years. Patients were divided into two groups using a cutoff value of 100 HU for the mean L2-5 vertebral HU values. We compared background data, surgical data, cage subsidence, bone fusion rates at 1 year and final follow-up, postoperative fragility fractures, revision surgeries due to bone fragility, final JOA scores, and final mobility scores between the groups.

Results: Fifty-two patients were classified into the low HU group. The rates of cage subsidence, bone fusion at 1 year, final bone fusion, postoperative fragility fractures, revision surgeries, final JOA scores, and final mobility scores were 19%, 46%, 83%, 17%, 2%, 22 points, and 3.5 points in the low HU group, compared to 6%, 56%, 88%, 21%, 2%, 22 points, and 3.5 points in the control group, respectively. While the low HU group showed significantly higher rates of cage subsidence, there were no significant differences in other complications or clinical outcomes between the groups.

Conclusions: In single-level PLIF, low vertebral HU values were identified as a risk factor for cage subsidence. However, there were no significant differences in final clinical outcomes or activities of daily living between the groups.

Introduction: This study aimed to investigate the effectiveness of McKenzie method (mechanical diagnosis and therapy [MDT]) for chronic low back pain.

Methods: This was a retrospective cohort study. A total of 410 patients, who had low back pain for >3 months and received outpatient treatment at our hospital, participated. The subjects were divided into two groups based on the presence (MDT [+] group, n = 238) or absence (MDT [−] group, n = 172) of MDT, as well as stretching and trunk muscle exercise in exercise therapy. Results were compared at 1 and 3 months after the exercise therapy between the two groups using the visual analog scale (VAS), Oswestry Disability Index (ODI), and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) for low back pain and its symptoms.

Results: Both groups had better scores of VAS, ODI, and JOABPEQ at 1 and 3 months post-treatment than pretreatment. The MDT (+) groups had notably higher increased score of walking ability in JOABPEQ than the MDT (−) group at 1 and 3 months post-treatment.

Conclusions: MDT considerably improved the walking ability within a short duration, suggesting that MDT might be useful for improving the quality of life in patients with chronic low back pain.

Introduction: We examined the preoperative predictors of lower back pain relief by decompression for lumbar spinal stenosis.

Methods: We analyzed 148 patients who underwent decompression using lumbar spinous process-splitting laminectomy for lumbar spinal stenosis complicated by lower back pain. They consisted of 90 male and 58 female patients with a mean age of 72 years, and the mean observation period was 305 days. Of these patients, 113 with improved preoperative visual analog scale (VAS) scores for lower back pain at final observation were classified as the R group, while 35 with no improvement were classified as the NR group; we compared both groups.

Results: The R and the NR groups had the following respective characteristics: 71 and 19 male patients, mean ages of 71.3 and 72.9 years, mean numbers of decompressed intervertebral segments of 2.2 and 2.1 segments, 37 and 8 patients with slips, 15 and 6 patients with degenerative scoliosis, 27 and 12 patients with modic changes, and 36 and 6 patients with sacroiliac joint degeneration, with no significant differences between both groups. The respective mean preoperative Japanese Orthopedic Association scores were 21.6 and 14.1 points, the mean preop VAS scores for lower back pain were 66.2 and 46.4 mm, the mean preoperative VAS scores for lower limb pain were 72.1 and 55.8 mm, and the mean preop VAS scores for lower limb numbness were 67.3 and 54.7 mm, with a significant difference in preoperative VAS for lower back pain and for lower limb pain. No significant difference was found in any of the items of the preoperative Japanese Orthopedic Association Back Pain Evaluation Questionnaire. With regard to preoperative spinopelvic parameters, the respective mean pelvic incidence (PI) were 50.4° and 50.3°, the mean pelvic tilts were 23.4° and 21.2°, the mean sacral slopes were 26.9° and 29.1°, the mean lumbar lordosis (LL) angles were 35.7° and 38.1°, the mean thoracic kyphosis angles were 25.5° and 24.6°, the mean PI-LL were 14.7° and 12.2°, the mean sagittal vertical axes were 53.3 and 53.9 mm, and the mean distance between the C7 plumb line and the central sacral vertical line were 2.9 and 0.9 mm to the right, with no significant differences.

Conclusions: Decompression for lumbar spinal stenosis may relieve lower back pain if the preoperative VAS score for lower back pain is high.