Analysis of spinopelvic parameters in adult patients with lumbosacral transitional vertebrae.

PURPOSE: Spinopelvic sagittal alignment is crucial for assessing balance and determining treatment efficacy in patients with adult spinal deformity (ASD). Only a limited number of reports have addressed spinopelvic parameters and lumbosacral transitional vertebrae (LSTV). Our primary objective was to study spinopelvic sagittal parameter changes in patients with LSTV. A secondary objective was to investigate clinical symptoms and quality of life (QOL) in patients with LSTV. METHODS: In this study, we investigated 371 participants who had undergone medical check-ups for the spine. LSTV was evaluated using Castellvi's classification, and patients were divided into LSTV+ (type II-IV, L5 vertebra articulated or fused with the sacrum) and LSTV- groups. After propensity score matching for demographic data, we analyzed spinopelvic parameters, sacroiliac joint degeneration, clinical symptoms, and QOL for these two participant groups. Oswestry Disability Index (ODI) scores and EQ-5D (EuroQol 5 dimensions) indices were compared between the two groups. RESULTS: Forty-four patients each were analyzed in the LSTV + and LSTV- groups. The LSTV + group had significantly greater pelvic incidence (52.1 ± 11.2 vs. 47.8 ± 10.0 degrees, P = 0.031) and shorter pelvic thickness (10.2 ± 0.9 vs. 10.7 ± 0.8 cm, P = 0.018) compared to the LSTV- group. The "Sitting" domain of ODI (1.1 ± 0.9 vs. 0.6 ± 0.7, P = 0.011) and "Pain/Discomfort" domain of EQ-5D (2.0 ± 0.8 vs. 1.6 ± 0.7, P = 0.005) were larger in the LSTV + group. CONCLUSION: There was a robust association between LSTV and pelvic sagittal parameters. Clinical symptoms also differed between the two groups in some domains. Surgeons should be aware of the relationship between LSTV assessment, radiographic parameters and clinical symptoms.

Does global spinal alignment affect the use of walking aids after multi-segment spinal fixation for patients with ASD? A multicenter retrospective study.

PURPOSE: This study aimed to clarify the relation between global spinal alignment and the necessity of walking aid use in patients with adult spinal deformity (ASD) and to investigate the impact of spinal fixation on mobility status after surgery. METHODS: In total, 456 older patients with ASD who had multi-segment spinal fixation surgery and were registered in a multi-center database were investigated. Patients under 60 years of age and those unable to walk preoperatively were excluded. Patients were classified by their mobility status into the independent, cane, and walker groups. Comparison analysis was conducted using radiographic spinopelvic parameters and the previously reported global spine balance (GSB) classification. In addition, preoperative and 2 years postoperative mobility statuses were investigated. RESULTS: Of 261 patients analyzed, 66 used walking aids (canes, 46; walkers, 20). Analysis of preoperative radiographical parameters showed increased pelvic incidence and pelvic incidence-lumbar lordosis mismatch in the walker group and increased sagittal vertebral axis in the cane and walker groups versus the independent group. Analysis of GSB classification showed a higher percentage of walker use in those with severe imbalance (grade 3) in the sagittal classification but not in the coronal classification. While postoperative radiographical improvements were noted, there was no significant difference in the use of walking aids before and 2 years after surgery (P = 0.085). CONCLUSION: A significant correlation was found between "sagittal" spinal imbalance and increased reliance on walking aids, particularly walkers. However, the limitation of improvement in postoperative mobility status suggested that multiple factors influence the mobility ability of elderly patients with ASD.

Longitudinal impact of multi-segment spinal fixation surgery on mobility status and clinical outcomes in adult spinal deformity: a multicenter retrospective study.

PURPOSE: To investigate changes in postoperative mobility status in patients with ASD, and the determining factors that influence these changes and their impact on clinical outcomes, including the rate of home discharge and long-term mobility. METHODS: A total of 299 patients with ASD who underwent multi-segment posterior spinal fusion were registered in a multi-center database were investigated. Patient mobility status was assessed using walking aids and classified into five levels (1: independent, 2: cane, 3: walker, 4: assisted, and 5: wheelchair) preoperatively, at discharge, and after 2 years. We determined improvements or declines in the patient's mobility based on changes in the classification levels. The analysis focused on the factors contributing to the deterioration of postoperative mobility. RESULTS: Two years postoperatively, 87% of patients maintained or improved mobility. However, 27% showed decreased mobility status at discharge, associated with a lower rate of home discharge (49% vs. 80% in the maintained mobility group) and limited improvement in mobility status (35% vs. 5%) after 2 years. Notably, postoperative increases in thoracic kyphosis (7.0 ± 12.1 vs. 2.0 ± 12.4°, p = 0.002) and lower lumbar lordosis (4.2 ± 13.1 vs. 1.8 ± 12.6°, p = 0.050) were substantial factors in mobility decline. CONCLUSION: Postoperative mobility often temporarily decreases but generally improves after 2 years. However, an overcorrection in sagittal alignment, evidenced by increased TK, could detrimentally affect patients' mobility status. Transient mobility decline associated with overcorrection may require further rehabilitation or hospitalization. Further studies are required to determine the biomechanical effects of surgical correction on mobility.

Preoperative low Hounsfield units in the lumbar spine are associated with postoperative mechanical complications in adult spinal deformity.

PURPOSE: To determine the most valid bone health parameter to predict mechanical complications (MCs) following surgery for adult spinal deformity (ASD). METHODS: This multicenter study retrospectively examined the records of patients who had undergone fusion of three or more motion segments, including the pelvis, with a minimum two-year follow-up period. Patients with moderate and severe global alignment and proportion scores were included in the study and divided into two groups: those who developed MCs and those who did not. Bone mineral density (BMD) of the lumbar spine and femoral neck was measured using dual-energy X-ray absorptiometry, and Hounsfield units (HUs) were measured in the lumbar spine on computed tomography. Radiographic parameters were evaluated preoperatively, immediately after surgery, and at final follow-up. RESULTS: Of 108 patients, 30 (27.8%) developed MCs, including 26 cases of proximal junctional kyphosis/failure, 2 of distal junctional failure, 6 of rod fracture, and 11 reoperations. HUs were significantly lower in patients who experienced MCs (113.7 ± 41.1) than in those who did not (137.0 ± 46.8; P = 0.02). BMD did not differ significantly between the two groups. The preoperative and two-year postoperative global tilt, as well as the immediately postoperative sagittal vertical axis, were significantly greater in patients who developed MCs than in those who did not (P = 0.02, P < 0.01, and P = 0.01, respectively). CONCLUSION: Patients who experienced MCs following surgery for ASD had lower HUs than those who did not. HUs may therefore be more useful than BMD for predicting MCs following surgery for ASD.

An appropriate method for predicting the femoral angle on whole-body X-ray images from full-spine X-ray images.

INTRODUCTION: The importance of lower-limb compensation in patients with spinal malalignment due to spinal pathologies has been emphasized. The latest whole-body X-ray images (WBX) have enabled evaluations of whole-body alignment from head to toe. However, WBX is still not commonly available. Thus, the present study aimed to examine an alternative measurement method of the femoral angle on usual full-spine X-ray images (FSX) that approximates the femoral angle on WBX. METHODS: A total of 50 patients (age, 52.8 ± 25.3 years; female, n = 26; male, n = 24) underwent WBX and FSX. The following parameters were measured on lateral view X-rays: WBX and FSX femoral angle (angle between the femoral axis and a perpendicular line); FSX femoral distance (distance from the center of femoral head to the distal femur on FSX); WBX intersection length (length between the center of the femoral head and the intersection point [the point at which the line connecting the center of the femoral head and the midpoint of the femoral condyle intersects the center line of the femur] on WBX). RESULTS: The WBX femoral angle, and FSX femoral angle were 0.16 ± 4.2°, and -0.53 ± 4.1°, respectively. The FSX femoral distance was 102.7 ± 41.1 mm. An ROC curve analysis revealed that the cut-off value of the FSX femoral distance associated with minimal difference in the WBX and FSX femoral angles (<3°) was 73 mm (sensitivity 83.3%, specificity 87.5%, AUC 0.80). The WBX intersection length was 105.3 ± 27.3 mm. CONCLUSION: To calculate the femoral angle on FSX that approximates the WBX femoral angle, the femoral distance on FSX ≥73 mm is preferable. We suggest using the FSX femoral distance within the range of 80 mm-130 mm as a simple numerical value that meets all criteria.

The anatomical relationship between the celiac artery and the median arch ligament in degenerative spinal surgery.

BACKGROUND: This study aimed to characterize the anatomical relationship between the spine, the celiac artery (CA), and the median arcuate ligament using preoperative contrast-enhanced computed tomography (CT) images of patients with spinal deformity who underwent surgical correction. METHODS: This retrospective study included 81 consecutive patients (34 males, 47 females; average age: 70.2 years). The spinal level at which the CA originated, the diameter, extent of stenosis, and calcification were determined using CT sagittal images. Patients were divided into two groups: CA stenosis group and non-stenosis group. Factors associated with stenosis were examined. RESULTS: CA stenosis was observed in 17 (21%) patients. CA stenosis group had significantly higher body mass index (24.9 ± 3.9 vs. 22.7 ± 3.7, p = 0.03). In the CA stenosis group, J-type CA (upward angling of the course by more than 90° immediately after descending) was more frequently observed (64.7% vs. 18.8%, p < 0.001). The CA stenosis group had lower pelvic tilt (18.6 ± 6.7 vs. 25.1 ± 9.9, p = 0.02) than non-stenosis group. CONCLUSIONS: High BMI, J-type, and shorter distance between CA and MAL were risk factors for CA stenosis in this study. Patients with high BMI undergoing fixation of multiple intervertebral corrective fusions at the thoracolumbar junction should undergo preoperative CT evaluation of the anatomy of CA to assess the poteitial risk of celiac artery compression syndrome.

Racial differences in whole-body sagittal alignment between Asians and Caucasians based on international multicenter data.

PURPOSE: To examine inherent differences adjusted for age and clinical score in whole-body sagittal (WBS) alignment involving the lower extremities between Asians and Caucasians, and to determine the relationship between age and WBS parameters by race and sex. METHODS: A total of 317 individuals consisting of 206 Asians and 111 Caucasians participated. WBS parameters including C2-7 lordotic angle, lower lumbar lordosis (lower LL, L4-S), pelvic incidence (PI), pelvic thickness, knee flexion (KF), sagittal vertical axis (SVA), and T1 pelvic angle (TPA) were evaluated radiologically. Propensity score-matching adjustments for age and the Oswestry Disability Index scores for comparative analysis between the two race cohorts and correlation analysis between age and WBS parameters for all subjects by race and sex were conducted. RESULTS: The comparative analysis included 136 subjects (age: Asians 41.1 ± 13.5, Caucasians 42.3 ± 16.2 years, p = 0.936). Racial differences in WBS parameters were observed in C2-7 lordotic angle (-1.8 ± 12.3 vs. 6.3 ± 12.2 degrees, p = 0.001), and lower LL (34.0 ± 6.6 vs. 38.0 ± 6.1 degrees, p < .001). In correlation analysis with age, moderate or more significant correlations with age were found in KF for all groups, and in SVA and TPA for females of both racial groups. Age-related changes in pelvic parameters of PI and pelvic thickness were more significant in Caucasian females. CONCLUSION: Analysis of the correlation between age and WBS parameters suggested that age-related WBS changes vary between races and should be considered during corrective spinal surgery.

The age-specific normative values of standing whole-body sagittal alignment parameters in healthy adults: based on international multicenter data.

PURPOSE: To investigate the age-specific normative values of whole-body sagittal alignment (WBSA) including global balance parameters in healthy adults and to clarify the correlations among parameters based on the data from three international multicenter. METHODS: Three hundred and seventeen healthy subjects (range: 20-84 y.o., mean: 43.8 ± 14.7 y.o.) were included and underwent whole-body biplanar X-ray imaging system. Spinopelvic parameters and knee flexion (KF), the center of acoustic meatus (CAM)-hip axis (HA), and C2 dentiform apophyse (OD)-HA, the cranial center (Cr)-HA were evaluated radiologically. Sub-analysis for correlation analysis between age and parameters and among parameters was performed to investigate age-specific change and compensatory mechanisms. RESULTS: For age-related change, C2-7 angle (r = .326 for male/.355 for female), KF (r = .427/.429), and SVA (r = .234/.507) increased with age in both male and female group. For global parameters related to the center of the gravity, correlations with age were not significant (r = .120/.161 for OD-HA, r = .163/.275 for Cr-HA, r = .149/.262 for CAM-HA). Knee flexion (KF) has correlation with global parameters (i.e., SVA, OD-HA, Cr-HA, CAM-HA) and does not have correlations with local spinopelvic alignment. CONCLUSION: While several local alignment changes with age were found, changes in global parameters related to the center of gravity were kept relatively mild by the chain of compensation mechanisms including the lower limbs. We showed the normative values for a comprehensive WBSA in standing posture from large international healthy subjects' database.

Utility of ultrasonography in the diagnosis of lumbar spondylolysis in adolescent patients.

BACKGROUND: This study aims to investigate the utility of the Doppler effect on ultrasonography for the diagnosis of very early- and early-stage lumbar spondylolysis in adolescent patients. METHODS: In total, 76 adolescent patients with acute and subacute low back pain were prospectively enrolled, with 46 having lumbar spondylolysis and the remaining 30 having low back pain without spondylolysis. MRI and/or computed tomograms scans revealed very early- and early-stage lumbar spondylolysis. Furthermore, positive Doppler findings in ultrasonography around the area from the facet joint to the laminae were investigated. RESULTS: There were no significant differences in age (p > 0.99) and body mass index (p = 0.11) between cases with and without spondylolysis. Very early- and early-stage spondylolysis were observed in 27.6% and 72.4% of patients, respectively. Positive power Doppler was 91.3% and 33.3% in cases with and without spondylolysis, respectively, which was significantly higher in spondylolysis (p < 0.001). The sensitivity and specificity of this positive power Doppler were 91.4% and 66.7%, respectively. Furthermore, the rate of positive power Doppler was significantly higher in early-stage spondylolysis (p = 0.02), with 75.0% and 97.6% sensitivity in very early- and early-stage spondylolysis, respectively. CONCLUSIONS: A positive Doppler effect on ultrasonography is effective for screening very early- and early-stage spondylolysis in adolescent patients in an outpatient clinic.

The prevalence and characteristics of diffuse idiopathic skeletal hyperostosis in the community-living middle-aged and elderly population: The Yakumo study.

BACKGROUND: The incidence of diffuse idiopathic skeletal hyperostosis (DISH) is increasing with the aging of the population. Asymptomatic DISH can decrease the spinal range of motion (ROM) and cause fractures. However, the prevalence or physical function of patients with DISH before experiencing fractures and other serious conditions is unclear. This study aimed to investigate the prevalence of DISH in the community residents on the basis of age and sex and characterize their physical function, ROM, and bone fragility. METHODS: The subjects were community volunteers who attended a health checkup in 2018 and 2019. Overall, 455 subjects (mean age, 64.2 ± 9.7 years; 177 men) were included for analysis. We performed whole-spine lateral radiography for detecting DISH according to the criteria reported by Resnick. We compared the age, sex, body mass index (BMI), results of muscle strength and walking tests, ROM measured by SpinalMouse®, and quantitative ultrasound (QUS) of calcaneus with and without DISH. RESULTS: DISH was detected in 83 (18.2%) cases. The DISH group was older (69.8 y.o. vs. 63.0 y.o.; p < 0.05) and comprised more men (prevalence: men, 27.7%; women, 12.2%; p < 0.001). BMI was high in the DISH group (24.8 vs. 23.3 kg/m2, p < 0.05). SpinalMouse measurements showed the DISH group had a significantly decreased ROM in the lumbar spine (43.2°, 57.2°, p < 0.05). The DISH group had a significantly lower T-score on the QUS measurement in the calcaneus (-2.0, -1.5, p < 0.05). There were, however, no significant differences between groups in both muscle strength test and walking test. CONCLUSION: Subjects with DISH had decreased ROM in the lumbar spine and bone mineral density in calcaneal QUS. However, physical functions such as muscle strength and walking ability were similar among subjects with and without DISH without subjective symptoms.

Vertebral Endplate Concavity in Lateral Lumbar Interbody Fusion: Tapered 3D-Printed Porous Titanium Cage versus Squared PEEK Cage.

Background and Objectives: To prevent postoperative problems in extreme lateral interbody fusion (XLIF), it is critical that the vertebral endplate not be injured. Unintentional endplate injuries may depend on the cage. A novel porous titanium cage for XLIF has improved geometry with a tapered tip and smooth surface. We hypothesized that this new cage should lead to fewer endplate injuries. Materials and Methods: This retrospective study included 32 patients (mean 74.1 ± 6.7 years, 22 females) who underwent anterior and posterior combined surgery with XLIF for lumbar degenerative disease or adult spinal deformity from January 2018 to June 2022. A tapered 3D porous titanium cage (3DTi; 11 patients) and a squared PEEK cage (sPEEK; 21 patients) were used. Spinal alignment values were measured on X-ray images. Vertebral endplate concavity (VEC) was defined as concavity ≥ 1 mm of the endplate on computed tomography (CT) images, which were evaluated preoperatively and at 1 week and 3 months postoperatively. Results: There were no significant differences in the patient demographic data and preoperative and 3-month postoperative spinal alignments between the groups. A 3DTi was used for 25 levels and an sPEEK was used for 38 levels. Preoperative local lordotic angles were 4.3° for 3DTi vs. 4.7° for sPEEK (p = 0.90), which were corrected to 12.3° and 9.1° (p = 0.029), respectively. At 3 months postoperatively, the angles were 11.6° for 3DTi and 8.2° for sPEEK (p = 0.013). VEC was present in 2 levels (8.0%) for 3DTi vs. 17 levels (45%) for sPEEK (p = 0.002). After 3 months postoperatively, none of the 3DTi had VEC progression; however, eight (21%) levels in sPEEK showed VEC progression (p = 0.019). Conclusions: The novel 3DTi cage reduced endplate injuries by reducing the endplate load during cage insertion.

Impact of the hip joint mobility on whole-body sagittal alignment: prospective analysis in case with hip arthroplasty.

PURPOSE: To clarify the impact of restriction of hip extension on radiographic whole-body sagittal alignment with using postoperative changes of radiographical parameters for hip osteoarthritis. METHODS: We prospectively enrolled 68 patients with hip osteoarthritis scheduled for arthroplasty. Variables included manual examination of hip range of motion (H-ROM) and radiographic whole-body sagittal alignment parameters including sagittal vertical axis (SVA), center of acoustic meatus and femoral head offset (CAM-HA), thoracic kyphosis (TK), lumbar lordosis, sacral slope (SS), and knee flexion angle (KF). We divided patients with preoperative hip extension angle < 0 into the extension restriction (ER) + group and ≥ 0 into the ER- group. Differences in H-ROM, radiographic parameters between groups and postoperative changes were comparatively analyzed. RESULTS: Fifty-seven patients (The ER + group included 28 patients and the ER- group included 29 patients.) were available for the analysis. Pre-/postoperative H-ROM were 99.7 ± 24.9/118.1 ± 16.0 degrees (p < .01). Greater increases in SVA (5.4 ± 3.4 vs 3.4 ± 2.8 cm, p = .02) and in CAM-HA (3.9 ± 3.9 vs 2.8 ± 3.4 cm, p = 013) were found in the ER + group versus ER- group. Postoperatively, the ER + group showed an increase in TK (pre-/postoperative: 35.2 ± 9.7/37.4 ± 8.8 degrees, p = .04) and decreases in SS (36.5 ± 9.6/33.7 ± 9.9 degrees, p < .01) and KF (9.5 ± 7.0/6.9 ± 6.0 degrees, p = .02). Postoperative changes in radiographic parameters in the ER- group were not significant. CONCLUSION: Patients with restriction of hip extension showed global spine imbalance, and significant changes in TK, SS, and KF were observed after arthroplasty. The presence of hip joint disorder and H-ROM restriction must be considered when evaluating spinopelvic alignment and whole-body sagittal alignment.

Conservative treatment of spondylolysis involving exercise initiated early and sports activities resumed with a lumbar-sacral brace.

BACKGROUND: Conservative treatment including the use of a brace and cessation of sports activities is known to be effective in spondylolysis. However, there is some controversy regarding [1] the type of brace, and [2] the endpoint for bracing, and [3] the timing of resumption of sports activities. The aim of the current study was to investigate the appropriateness of early exercise and resumption of sports activities with a lumbar-sacral brace in very early- and early-stage lumbar spondylolysis. METHODS: This prospective cohort study enrolled 45 patients with very early- and early-stage lumbar spondylolysis. A lumbar-sacral brace, structured to be a hard brace in the back and a mesh brace in the front, was used. Isometric exercises/stretching was started immediately after the initial visit. The number of patients for whom bone fusion was fully achieved on CT and the disappearance of signal intensity change on MRI were investigated. RESULTS: In 12 cases of very early-stage spondylolysis, the average elapsed time until signal intensity disappearance as confirmed on MRI was 4.3 ± 1.6 months. Bony union on CT was confirmed in all cases. In 33 cases of early spondylolysis, signal intensity change disappeared on MRI within 5.2 ± 2.4 months. The rate of bony union was 94.3%, and the average period required to achieve bony union observable on CT was 3.7 ± 1.0 months. CONCLUSIONS: Sufficient bony union can be achieved by conservative treatment with early exercise and a lumbar-sacral brace in cases of very early and early spondylolysis.

Simultaneous single-position lateral interbody fusion and percutaneous pedicle screw fixation using O-arm-based navigation reduces the occupancy time of the operating room.

PURPOSE: Lateral interbody fusion and posterior percutaneous pedicle screw (LIF-PPS) fixation has been performed in two-stage positioning. The aim of this study was to investigate the surgical outcomes of simultaneous single-position LIF-PPS fixation using O-arm-based navigation. METHODS: Overall, 102 consecutive subjects underwent indirect decompression surgery for spondylolisthesis with LIF-PPS fixation. Fifty-one subjects underwent surgery with repositioning, and 51 in the right lateral decubitus position. We compared these two groups in terms of the surgery time, occupancy time in the operating room, intraoperative blood loss, Japanese Orthopaedic Association (JOA) score, local lordosis acquisition in postoperative radiographs, and accuracy of screw insertion using postoperative CT scans. RESULTS: In the single-position group, surgery time, occupancy time of the operating room, and estimated blood loss were 93.3 ± 19.3 min (vs. the repositioning group: 121.0 ± 37.1 min; p < 0.001), 176.3 ± 36.4 min (vs. 272.4 ± 42.7 min; p < 0.001), and 93.4 ± 78.8 ml (vs. 40.9 ± 28.7 ml; p < 0.001), respectively. The JOA scores (pre-/postoperative) were 15.1 ± 3.0/24.4 ± 2.8 (p < 0.001) for the single-position group and 15.1 ± 4.0/24.8 ± 3.0 (p < 0.001) for the repositioning group. The rate of misplacement was 1.8% versus 4.0%, respectively (p = 0.267), and the lordosis acquisition was 4.2° ± 4.1° versus 4.4° ± 3.2°, respectively (p = 0.516). CONCLUSIONS: Single-position surgery exhibited comparable clinical outcomes and local lordosis acquisition with conventional repositioning LIF-PPS fixation. This single-position minimally invasive technique reduces the occupancy time of the operating room and workforce requirements. These slides can be retrieved under Electronic Supplementary Material.

Anatomic evaluation of retroperitoneal organs for lateral approach surgery: a prospective imaging study using computed tomography in the lateral decubitus position.

PURPOSE: The aim of this study is to investigate retroperitoneal organ distribution with the retroperitoneal approach in the lateral decubitus position. METHODS: We enrolled 100 patients scheduled for lateral approach surgery, including LIF and lateral corpectomy. We performed computed tomography with lateral decubitus positioning (L-CT) to assess the position of the organs, including abdominal aorta, kidney, descending colon, ureter, and gonadal artery. Anteroposterior organ positions were divided into four zones: A, anterior to the anterior margin of the vertebral body; AL, anterior margin to the middle line of the vertebral body; PL, middle line to the posterior margin of the vertebral body; and P, posterior to the posterior margin of the vertebral body. We defined zone PL-P as the "approach zone." Measurements obtained using L-CT were compared with those obtained in the conventional supine position (S-CT). RESULTS: Retroperitoneal organs in the approach zone significantly decreased in lateral positioning. Eighty-three percent of kidney and 20% of descending colon remain in the approach zone in L-CT. Sixty-six percent of disk levels recorded for the descending colon in zone P in S-CT remained in the approach zone even in L-CT. CONCLUSIONS: We observed anterior migration in L-CT in all retroperitoneal organs. However, a considerable percentage of kidney and that of descending colon remain obstruent while performing LIF. We discuss that the preoperative imaging evaluation is beneficial, and gentle and meticulous surgical detachment is essential for safe and reliable lateral approach surgery, especially in the case that the descending colon extends outside zone P in S-CT. These slides can be retrieved under electronic supplementary material.

Functional computed tomography scanning for evaluating fusion status after anterior cervical decompression fusion.

INTRODUCTION: Nonunion is a major complication of anterior cervical fusion that causes poor outcomes and occasionally requires additional operative intervention. The purpose of this study is to evaluate the accuracy of functional computed tomography (CT) scanning for determining fusion status after anterior cervical fusion by comparing with functional radiographs. MATERIALS AND METHODS: The fusion status in 59 patients treated by anterior cervical fusion was assessed by functional radiography and functional CT scanning at 6 and 12 months after surgery. Fusion rates and clinical symptoms were evaluated. Fusion on functional radiography was defined as less than 2 mm of motion between adjacent spinous processes and a particular bony trabeculation on functional CT; fusion was defined as nonexistence of a clear zone or a gas pattern and a particular bone connection on reconstructed sagittal-view images. RESULTS: Functional radiographs demonstrated solid fusion in 83.9% at 6 months and 91.1% at 12 months postoperatively; functional CT showed solid fusion in 55.3 and 78.6%, respectively. The fusion rate detected on functional CT images was significantly lower than that on functional radiographs at each period. At 6 months postoperatively, patients with incomplete union on functional CT were more likely to have neck pain than those who had complete union on functional CT. (46.2 vs 13.3%, P < 0.05) CONCLUSION: Functional CT can detect nonunion more clearly than functional radiography. At 6 months postoperatively, patients with incomplete union on functional CT images were likely to have more neck pain. Functional CT may allow accurate detection of symptomatic nonunion after anterior cervical fusion.

Treatment outcomes of intradiscal steroid injection/selective nerve root block for 161 patients with cervical radiculopathy.

Patients with cervical radiculopathy (CR) were treated with intradiscal injection of steroids (IDIS) and/or selective nerve root block (SNRB) at our hospital. We retrospectively report the outcomes of these nonsurgical treatments for CR. 161 patients who were followed up for >2months were enrolled in this study. Patients' clinical manifestations were classified as arm pain, arm numbness, neck and/or scapular pain, and arm paralysis. Improvement in each manifestation was classified as "disappeared," "improved," "poor," or "worsened." Responses of "disappeared" or "improved" manifestations suggested treatment effectiveness. Final clinical outcomes were evaluated using the Odom criteria. Changes in herniated disc size were evaluated by comparing the initial and final MRI scans. On the basis of these changes, the patients were divided into regression, no-change, or progression groups. We investigated the relationship between the Odom criteria and changes observed on MRI. Effectiveness rates were 89% for arm pain, 77% for arm numbness, 82% for neck and/or scapular pain, and 76% for arm paralysis. In total, 91 patients underwent repeated MRI. In 56 patients (62%), the size of the herniated disc decreased, but 31 patients (34%) exhibited no change in disc size. The regression group showed significantly better Odom criteria results than the no-change group. In conclusion, IDIS and SNRB for CR are not widely performed. However, other extremely effective therapies that can rapidly improve neuralgia should be considered before surgery.

A novel technique for C1-C2 posterior screw insertion using patient-specific guides created by CT-based 3D printing.

C1-C2 fixation has been developed for the rigid fusion of atlantoaxial instability. C1 lateral mass screw (C1 LMS)-C2 pedicle screw fixation is used more frequently due to its rigid fixation and high bone fusion rate. However, C1 screw placement is relatively unsafe even with recently developed image-based navigation systems. Patient-specific screw guide templates (PSGT) were developed to improve the accuracy and safety of C1 screw placement. Herein, we investigated the outcomes of the C1-C2 posterior fixation technique using PSGT. This was a retrospective study of six patients who underwent posterior cervical spinal fusion using the PSGT between January 2022 and April 2023. Operative time, estimated blood loss, intraoperative radiation dose, surgical cost, and screw placement accuracy were evaluated and compared with those achieved with preoperative CT-based navigation (navigation group, n = 15). Screw accuracy was assessed using Neo's classification. PSGT showed good results, although the differences were not statistically significant (operation time: 104.3 ± 9.7 min vs 116.4 ± 20.8 min; estimated blood loss: 56.7 ± 72.4 mL vs 123.2 ± 162.3 mL; and radiation dose: 1.8 ± 1.2 mSv vs 2.6 ± 0.8 mSv, respectively). PSGT was particularly better in terms of the accuracy of C1 LMS (PSGT: 100%, navigation: 83.3%). The deviation at the entry point was minimal, and the difference between the sagittal and transversal angles from the preoperative plan was small. We investigated the clinical efficacy of using the PSGT for C1-C2 posterior fixation. PSGT improved the accuracy of C1 LMS insertion.

Trabecular Bone Remodeling after Posterior Lumbar Interbody Fusion: Comparison of the Osseointegration in Three-Dimensional Porous Titanium Cages and Polyether-Ether-Ketone Cages.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Imaging changes in the vertebral body after posterior lumbar interbody fusion (PLIF) are determined to be trabecular bone remodeling (TBR). This study aimed to investigate the influence of cage materials on TBR and segment stabilization in PLIF by studying image changes. METHODS: This was a retrospective study reviewing 101 cases who underwent one-level PLIF with three-dimensional porous titanium (3DTi) cages (53 patients) or polyether-ether-ketone (PEEK) cages (48 patients). Computed tomography images obtained 3 months, 1 year, and 2 years postoperatively were examined for TBR, vertebral endplate cyst formation as an instability sign, cage subsidence, and clear zone around pedicle screw (CZPS). RESULTS: No significant differences in the TBR-positivity rates were observed between the two cages at 3 months, 1 year, and 2 years postoperatively. However, all 3DTi cage segments that were TBR-positive at 3 months postoperatively showed no CZPS and fewer final instability segments than the TBR-negative segments (0% vs 9%). In contrast, although the PEEK cage segments that were TBR-positive at 3 months postoperatively were not associated with future segmental stabilization, those that were TBR-positive at 1 year postoperatively had fewer final instability segments than the TBR-negative segments (0% vs 33%). CONCLUSIONS: The 3DTi cage segments with TBR 3 months postoperatively showed significant final segmental stabilization, whereas TBR at 1 year rather than 3 months postoperatively was useful in determining final segmental stabilization for the PEEK cage segments. The timing of TBR, a new osseointegration assessment, were associated with the cage material.