Factors influencing the achievement of early surgery in proximal femoral fractures under a Japanese incentive policy.

BACKGROUND: Proximal femoral fractures in geriatric patients are a major challenge in orthopedics, often leading to major functional impairment. Early surgical intervention is crucial for improving patient recovery and overall health outcomes. Thus, Japan's Ministry of Health, Labour and Welfare initiated a reimbursement policy in April 2022 to encourage early surgery for these fractures in patients aged ≥75 years. This study investigated the impact of this policy on early surgery rates in Japan and identified factors influencing the timing of surgical interventions. METHODS: We retrospectively analyzed the data of patients who underwent surgery for proximal femoral fractures at our institution between April 2022 and March 2023. Patients were categorized into two groups based on the timing of surgery relative to the injury: ≤48 h and >48 h. Demographic and clinical data, including age, sex, fracture type, and various health- and admission-related factors, were assessed. RESULTS: Of the 192 patients, 152 were included in the study. Among them, 38% underwent early surgery (≤48 h), and 15% of the patients arrived more than 48 h post-injury. Significant differences were found in admission routes and residence types between the groups. The ≤48 h group had shorter intervals from injury to admission and surgery than the >48 h group. Factors such as the admission process, day of the week, and C-reactive protein levels significantly influenced the timing of surgery. CONCLUSIONS: After introducing incentives for early surgery in Japan, 38% of patients with proximal femoral fractures underwent surgery within 48 h of injury. Factors contributing to patients not receiving early surgery included transport from another hospital, weekend hospitalization, and elevated CRP levels. These findings suggest that achieving surgery within 48 h of injury is challenging through hospital efforts alone, and the time criteria might be more appropriate if changed to "admission to surgery."

Association of Spinal Corrective Surgery With Abdominal Aorta Length in Patients With Adult Spinal Deformity.

Introduction This research aimed to explore the relationship between spinal characteristics and the length of the abdominal aorta in adult spinal deformity (ASD) patients who underwent corrective spinal surgery. We hypothesized that adjusting spinal alignment might affect the abdominal aorta's length. Methods This study included thirteen patients with ASD (average age: 63.0 ± 8.9 years; four males and nine females) who received spinal correction surgery. We measured both pre-operative and post-operative spinal parameters, including thoracolumbar kyphosis (TLK), and calculated their differences (Δ). The length of the aorta (AoL) was determined using an automated process that measures the central luminal line from the celiac artery's bifurcation to the inferior mesenteric artery. This measurement was made using contrast-enhanced computed tomography for three-dimensional aortic reconstruction. We compared the pre-operative and post-operative AoLs and their differences (Δ). The study examined the correlation between changes in spinal parameters and changes in AoL. Results Post-operatively, there was an increase in aortic length (ΔAoL: 4.2 ± 4.9 mm). There was a negative correlation between the change in TLK and the change in AoL (R2 = 0.45, p = 0.012, ß = -0.21). No significant correlations were found with other spinal parameters. Conclusions The abdominal aorta can elongate by 4.8% after spinal corrective surgery in patients with ASD. The degree of elongation of the abdominal aorta is associated with spinal alignment correction.

Measurement of Postoperative Apical Vertebral Rotation Using Radiographic Images in Adolescent Idiopathic Scoliosis-Quantitative Evaluation Using Inverse Trigonometric Functions.

Introduction: Conventional methods for analyzing vertebral rotation are limited to postoperative patients who underwent posterior fusion. A previous methodology calculated vertebral rotation using inverse trigonometric functions based on the length of the pedicle screw (PS). Accordingly, this study evaluates rotational deformity in patients with postoperative adolescent idiopathic scoliosis (AIS) using inverse trigonometric functions. Methods: This retrospective single-center study includes patients with AIS who underwent posterior fusion surgery. Postoperative radiography and computed tomography (CT) scans were retrospectively evaluated. The magnification ratio was calculated using the rod diameter (δ=lateral/frontal rod diameter), and the visible screw lengths were measured using radiographs. The rotation angle was calculated using the apex of the main curve and the lower instrumented vertebra (LIV) (rotation angle=tan-1 (lateral PS length/(δ×frontal PS length))) immediately following the surgery as well as two and five years postoperatively. The correlation between the direct CT measurement and postoperative rotation angle progression was investigated. The crankshaft phenomenon (CSP) and distal adding-on (DAO) were evaluated as postoperative deformities. CSP was defined as a 5° increase in rotation angle. Results: Seventy-eight patients (age: 15.3±2.0 years, eight boys and seventy girls) were included. The rotation angle was strongly correlated with CT rotation measurements (r=0.87). The mean rotation angle at the apex and LIV did not change within five years postoperatively (mean: 0.5±3.6° and 0.4±3.4°, respectively). CSP and DAO were observed in 6.4% and 3.8% of patients, respectively. Conclusions: The inverse trigonometric method is useful to quantitatively evaluate the postoperative rotation angle and identify CSP.

The Optimal Patient Position on the Surgical Table for Lateral Lumbar Interbody Fusion in Adult Spinal Deformity Using Three-Dimensional Computed Tomography: A Retrospective Study.

Introduction: Lateral lumbar interbody fusion (LLIF) techniques have been extensively used in adult spinal deformity surgery. Preoperative knowledge of the optimal position of the patient on the surgical table is essential for a safe procedure. Therefore, this study aims to determine the optimal angle for positioning the patient on the surgical table during LLIF using three-dimensional computed tomography (3DCT). Methods: Data from 59 patients (2 males, 57 females, mean age 66.3±8.6 years) with adult spinal deformities treated by performing corrective spinal surgery were included in this observational retrospective study. Simulated fluoroscopic images were obtained using 3DCT images rotated from the reference position with the spinous process of S1 as the midline to the position with the spinous process in the center of the bilateral pedicle of T12-L5. The rotation angle of each vertebra was measured and defined as the optimal rotation angle (ORA). The angle that bisected the angle between the maximum and minimum ORA was defined as the optimal mean angle of the maximum and minimum ORA (OMA) and considered the optimal angle for the patient's position on the surgical table, as this position could minimize the rotation angle of the surgical table during surgery. A multiple regression analysis was performed to predict OMA. Results: Multiple regression analysis revealed the following equation: OMA=1.959+(0.238×lumbar coronal Cobb angle)+(-0.208×sagittal vertical axis). Conclusions: When the patient is placed on the surgical table by rotating them at the OMA, the rotation of the surgical table can be reduced, ensuring a safe and efficient surgical procedure.

Bone union-promoting effect of romosozumab in an ovariectomized rat posterolateral lumbar fusion model.

Spinal fixation surgery has been increasingly performed in patients with osteoporosis. Romosozumab, a drug that was introduced in Japan recently, is known to possibly promote bone healing. However, few studies have reported the therapeutic effects of romosozumab in clinical practice in Japan. Therefore, here, we investigated the effects of romosozumab dosage on bone fusion promotion using an ovariectomized rat spinal fusion model. Eight-week-old female Sprague-Dawley rats were matched by body weight and divided into three groups: 1.0 romosozumab (R) group (Evenity®, 25 mg/kg), 1/10R group (Evenity®, 2.5 mg/kg), and control (C) group (saline). Subcutaneous injections were administered twice a week for 8 weeks postoperatively. Computed tomography scans were performed every 2 weeks from the time of surgery till 8 weeks postoperatively. The mean fusion rates in terms of volume were significantly higher in the R groups [1/10R, 1.0R] than in the C group from 4 weeks postoperatively. The rate of increase was significantly higher in the 1.0R group from 4 weeks postoperatively and in the 1/10R group from 6 weeks postoperatively, than in the C group. The proportion of trabecular bone area was approximately 1.5 times higher in the R groups than in the C group. No significant differences were observed between the R groups. Our results suggest that romosozumab stimulates bone growth at the graft site, and similar effects were achieved at 1/10 of the standard dosage.

Machine learning algorithms for predicting Cobb angle beyond 25 degrees in female adolescent idiopathic scoliosis patients.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To develop a machine learning (ML) model that predicts the progression of AIS using minimal radiographs and simple questionnaires during the first visit. SUMMARY OF BACKGROUND DATA: Several factors are associated with angle progression in patients with AIS. However, it is challenging to predict angular progression at the first visit. METHODS: Among female patients with AIS treated at a single institution from July 2011 to February 2023, 1119 cases were studied. Patient data, including demographic and radiographic data based on anterior-posterior and lateral whole-spine radiographs, were collected at the first and last visits. The last visit was defined differently based on treatment plans. For patients slated for surgery or bracing, the last visit occurred just before these interventions. For others, it was their final visit before turning 18 years. Angular progression was defined as a Cobb angle greater than 25 degrees for each of the proximal thoracic (PT), main thoracic (MT), and thoracolumbar/lumbar (TLL) curves at the last visit. ML algorithms were employed to develop individual binary classification models for each type of curve (PT, MT, and TLL) using PyCaret in Python. Multiple models were explored and analyzed, with the selection of optimal models based on the area under the curve (AUC) and Recall scores. Feature importance was evaluated to understand the contribution of each feature to the model predictions. RESULTS: For PT, MT, and TLL progression, the top-performing models exhibit AUC values of 0.94, 0.89, and 0.84, and achieve recall rates of 0.90, 0.85, and 0.81. The most significant factors predicting progression varied for each curve: initial Cobb angle for PT, presence of menarche for MT, and Risser grade for TLL. CONCLUSIONS: This study introduces an ML-based model using simple data at the first visit to precisely predict angle progression in female patients with AIS.

Analysis of the relationship between spinal alignment and retrocrural space area in adult spinal deformity surgery: Potential risk factors for acute celiac artery compression syndrome.

PURPOSE: This study was designed to reveal the association between spinal parameters and RCS area in patients with adult spinal deformities treated with spinal correction surgery. We hypothesized that reduction of the retrocrural space (RCS) area is related to thoracolumbar alignment, which may cause acute celiac artery compression syndrome (ACACS). METHODS: Eighty-nine patients (age: 68.4 ± 7.6 years; sex: 7 male/82 female) with ASD treated by spinal correction surgery were enrolled. Preoperative and postoperative spinal parameters were measured, and the differences between these parameters were calculated. Postoperative T12 translation was measured and RCS area was evaluated using reconstructed computed tomography. The change of RCS area after surgery was defined as ΔRCS. Patients were divided into increased and decreased RCS groups by the ΔRCS value, and spinal parameters were compared between groups. The correlation between spinal parameters and ΔRCS was calculated. RESULTS: The patients in the decreased RCS group had greater anterior T12 translation than those in the increased RCS group (p < 0.001). T12 translation was significantly correlated with ΔRCS (ß = -0.31, p = 0.017). There were no correlations between ΔRCS and other spinal parameters. CONCLUSION: Thoracolumbar alignment was associated with RCS area. Consistent with the hypothesis, overcorrection of the thoracolumbar junction was associated with reduced RCS area and might be one risk factor for ACACS.

Does vacuum phenomenon at non-fused discs affect the postoperative course after transforaminal lumbar interbody fusion in patients showing a positive value of difference in lumbar lordosis?

INTRODUCTION: Preoperative difference in lumbar lordosis (DiLL) was associated with surgical outcomes after single-level transforaminal lumbar interbody fusion (TLIF). Patients with DiLL>0 (DiLL (+)) tended to show worse clinical outcomes and postoperative greater restoration of lumbar lordosis (LL). However, some patients with DiLL (+) showed relatively good outcomes and no postoperative LL restration. This study aimed to elucidate whether the lumbar intervertebral disc vacuum phenomenon (VP) influences clinical course after single-level TLIF in patients with DiLL (+) and DiLL (-). METHODS: Patients with lumbar spinal stenosis and degenerative spondylolisthesis treated with single-level TLIF were included. Pre- and postoperative LL were measured, and postoperative LL improvement was calculated. Preoperative DiLL was calculated as preoperative supine LL minus standing LL. Severity of VP at the non-fused discs (SVP (non-FS)) was evaluated using preoperative reconstructed computed tomography imaging. Clinical outcomes were assessed using the Oswestry disability index, visual analogue scale (VAS; low back pain (LBP), lower-extremity pain, numbness, and the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire. Patients were stratified by the median preoperative SVP (non-FS) score into severe and mild VP groups in patients with DiLL (+) or DiLL (-), and their surgical outcomes were compared. RESULTS: Overall, 89 patients were included. In patients with DiLL (+) (n = 37), patients with severe VP showed worse clinical outcomes, particulary for LBP and DiLL (+) patients with mild VP showed greater LL improvement (6.5° ± 10.0°). In patients with DiLL(-) (n = 52), patients with severe VP showed worse clinical outcomes, particularly for LBP and no differences in preoperative, postoperative, and improvement of LL were observed between two groups. CONCLUSION: Patients with DiLL (+) and DiLL (-) showed different clinical courses depending on VP severity at the non-fused discs after single-level TLIF.

Median Arcuate Ligament and Origin of the Celiac Artery Proximity Change in Patients after Surgery to Correct Adult Spinal Deformity: Potential Risk Factors for Acute Celiac Artery Compression Syndrome.

Introduction: This study aimed to determine whether the proximity of the median arcuate ligament (MAL) and the celiac artery (CA) changes in patients following surgery to correct adult spinal deformity (ASD). We hypothesized that the distance between the MAL and the CA shortens after corrective spinal surgery, which may cause acute celiac artery compression syndrome (ACACS). Methods: A total of 89 patients (68.4±7.6 years; 7 men/82 women) with ASD treated with spinal correction surgery were included in the present retrospective study. The level of the MAL, CA, and distance between the MAL and the CA (DMC) were determined via reconstructed computed tomography. MAL overlap was determined preoperatively and postoperatively. Results: The MAL and CA moved caudally following surgery. On average, after surgery, no changes in DMC were observed. We found preoperative MAL overlap in 32 (36%) patients, who also had postoperative MAL overlap. No patients showed any MAL overlap postoperatively. Conclusions: Contrary to our hypothesis, the distance between the MAL and the CA did not shorten, and emerging MAL overlap was not observed postoperatively.

Incidence and Potential Risk Factors of Superior Mesenteric Artery Syndrome After Spinal Corrective Surgery in Patients with Adult Spinal Deformity.

OBJECTIVE: This study aimed to determine the incidence and potential risk factors of superior mesenteric artery syndrome (SMAS) after corrective spinal surgery in patients with adult spinal deformity (ASD). METHODS: In total, 102 patients (67.6 ± 8.4 years; 8 male/94 female; body mass index (BMI); 22.4 ± 3.6 kg/m2) with ASD treated by spinal correction surgery were enrolled. Preoperative and postoperative spinal parameters, including thoracolumbar kyphosis (TLK: T10-L2) and upper lumbar lordosis (ULL: L1-L4) were measured. To evaluate the potential risk factors of SMAS, the angle and the distance between the superior mesenteric artery and aorta, the aortomesenteric angle (AMA) and aortomesenteric distance (AMD), were evaluated pre- and postoperatively. Based on the postoperative AMA, AMD, and abdominal symptoms, the patients were diagnosed with SMAS. Correlations between demographic data or spinal parameters and AMA and AMD were assessed. RESULTS: Two (2.0%) patients were diagnosed with SMAS. Postoperative TLK significantly correlated with postoperative AMA (P = 0.013, 0.046). Postoperative ULL was significantly correlated with postoperative AMD (ß = -0.27; P = 0.014). CONCLUSION: The incidence of SMAS after corrective spinal surgery in patients with ASD was 2.0%. Postoperative smaller TLK and greater ULL can be risk factors for developing SMAS. Spine surgeons should avoid overcorrection of the upper lumbar spine in the sagittal plane to prevent SMAS.

The Association Between Corrective Surgery for Adult Spinal Deformity and Serum Levels of Hepatobiliary Enzymes.

Background and objective The surgery to correct adult spinal deformity (ASD) is associated with a rare, but life-threatening complication called acute celiac artery compression syndrome (ACACS). To our knowledge, there is currently no study in the literature regarding the abnormal elevation of serum levels of hepatobiliary enzymes after surgery to correct the deformity. In light of this, the purpose of this study was to investigate this potential association. Materials and methods We collected data on 74 patients with ASD who underwent correction surgery at our institution. A Spearman's rank-order correlation was used to assess the association between serum levels of hepatobiliary enzymes and spinal parameters. Factors showing a correlation coefficient of 0.2 or more were combined in a stepwise multiple regression analysis. Results The mean age of the patients was 68.4 ± 7.7 years; the study comprised six men and 68 women. In our stepwise multiple regression analysis, there were two valid models that included spinal parameters as independent variables: changes in lactate dehydrogenase (LDH) - changes in thoracolumbar kyphosis (TLK) (B -0.0025 ± 0.0007, p<0.01), and changes in LDH - preoperative T12-L1 kyphosis (B 0.0031 ± 0.001, p<0.01). Additionally, both valid models contained median arcuate ligament (MAL) overlap defined as MAL crossing the base of the celiac artery (CA) as a significant independent variable. Conclusions Greater sagittal correction of TLK, larger preoperative T12-L1 kyphosis, and MAL overlap were factors associated with an elevated serum level of LDH. Although few patients were reported to have clinically severe symptoms, "potential" ACACS due to a temporary blood flow disturbance can occur in this patient population.

Risk Factors for Cage Subsidence in Minimally Invasive Lateral Corpectomy for Osteoporotic Vertebral Fractures.

Introduction: This study aims to investigate risk factors for cage subsidence following minimally invasive lateral corpectomy for osteoporotic vertebral fractures. Methods: Eight males and 13 females (77.2±6.0 years old) with osteoporotic vertebral fractures who underwent single corpectomy using a wide-footprint expandable cage with at least a 1-year follow-up were retrospectively included. The endplate cage (EC) angle was defined as the angle between the vertebral body's endplate and the cage's base on the cranial and caudal sides. A sagittal computed tomography scan was performed immediately after surgery and at the final follow-up, with cage subsidence defined as subsidence of ≥2 mm on the cranial or caudal side. Risk factors were analyzed by dividing cases into groups with (n=6) and without (n=15) cage subsidence. Results: No significant differences were noted in age, bone mineral density, number of fixed vertebrae, sagittal parameters, preoperative and final kyphosis angle, amount of kyphosis angle correction, bone union, screw loosening, and number of other vertebral fractures preoperatively and 1-year postoperatively between the two groups. No difference was noted in cranial EC angle, but a significant difference was noted in caudal EC angle in the group with (10.7±4.1°) and without (4.7±4.2°) subsidence (P=0.008). Logistic regression analysis with the dependent variable as presence or absence of subsidence showed that caudal EC angle (>7.5°) was a significant factor (odds ratio: 20, 95% confidence interval: 1.655-241.7, P=0.018). Conclusions: In minimally invasive lateral corpectomy for osteoporotic vertebral fractures, a cage tilted more than 7.5° to the caudal vertebral endplate is a risk factor for cage subsidence. The cage should be placed as perpendicular to the endplate as possible, especially to the caudal vertebral body, to avoid cage subsidence.

Effect of Preoperative Severity and Location of Lumbar Intervertebral Disc Vacuum Phenomenon on Surgical Outcomes After Single-Level Transforaminal Lumbar Interbody Fusion.

OBJECTIVE: This study aimed to examine whether preoperative severity and location of lumbar intervertebral disc vacuum phenomenon (VP) influence surgical outcomes after single-level transforaminal lumbar interbody fusion. METHODS: We included 106 patients (age, 67.4 ± 10.4 years; 51 male/55 female) with lumbar degenerative diseases, who were treated with single-level transforaminal lumbar interbody fusion. Severity of VP (SVP) score was measured preoperatively. SVP score at fused disc was used as SVP (FS) score and at nonfused discs was used as SVP (non-FS) score. Surgical outcomes were assessed using the Oswestry Disability Index (ODI) and visual analog scale (VAS; low back pain (LBP), lower extremity pain, numbness, LBP in motion, in standing, and in sitting). The patients were divided into severe VP (FS or non-FS) and mild VP (FS or non-FS) groups, and surgical outcomes were compared between the 2 groups. Correlations between each SVP score and surgical outcomes were analyzed. RESULTS: There were no differences in surgical outcomes between the severe VP (FS) and mild VP (FS) groups. Postoperative ODI, VAS score for LBP, lower extremity pain, numbness, and LBP in standing were significantly worse in the severe VP (non-FS) group than in the mild VP (non-FS) group. SVP (non-FS) scores significantly correlated with postoperative ODI, VAS score for LBP, lower extremity pain, numbness, and LBP in standing; however, SVP (FS) scores did not correlate with any surgical outcomes. CONCLUSIONS: Preoperative SVP at fused disc is not associated with surgical outcomes; however, SVP at nonfused discs is correlated with clinical outcomes.

Risk factors for celiac artery and superior mesenteric artery stenosis in preoperative lumbar and thoracolumbar spinal surgery patients.

BACKGROUND: Ischemic necrosis of the abdominal organs caused by compression of the celiac artery (CA) and superior mesenteric artery (SMA) by the median arcuate ligament (MAL) after correction surgery has been recognized as acute celiac artery compression syndrome (ACACS). Here, using contrast-enhanced computed tomographic (CT) images, we sought to determine the prevalence and degree of CA and SMA stenosis in spinal patients preoperatively, and the risk factors associated with the stenosis. METHODS: We retrospectively examined contrast-enhanced abdominal CT of 90 patients with preoperative lumbar degenerative disease, lumbar burst fracture, or adult spinal deformity. The trunks of the CA and SMA were detected using three-dimensional reconstructed CT. To investigate their degree of stenosis, we determined the ratio of the narrowest diameter of the stenotic segment to the distal normal lumen's diameter. Patients with a degree of stenosis ≥35% were defined as being in the group with stenosis and the remainder as in the group without. To determine the risk factors for stenosis of these arteries, the relationship between the stenosis and CA and SMA calcification or the median arcuate ligament (MAL) crossing the proximal portion of the celiac axis (MAL overlap) was also investigated. RESULTS: The average degree of stenosis of the CA trunk was 12.1% ± 13.9% and that for the SMA trunk was 8.5% ± 8.8%. There were 8 patients (8.9%) in the group with CA stenosis and 2 patients (2.2%) in the group with SMA stenosis. The number of patients in the group with CA stenosis was significantly greater than the number with MAL overlap or CA calcification (P < 0.05). DISCUSSION: The prevalence of CA or SMA stenosis was 11.2% of preoperative patients due to undergo thoracolumbar fusion surgery. Calcifications of the CA trunk and MAL overlap are risk factors for CA stenosis.

Cooccurrence of Fragility Fracture of the Pelvis with Lumbar Degenerative Disease: A Case Report.

Introduction: Fragility fractures of the pelvis (FFP) are caused by low-energy impacts and can occur spontaneously in patients with severe osteoporosis. The clinical symptoms of FFP are frequently vague and nonspecific. Moreover, the symptoms of FFP can mimic lumbar spine pathologies. Therefore, accurate diagnosis of FFP is often difficult and the fracture may be misdiagnosed as lumbar degenerative disease. However, little is known regarding what kind of symptoms due to lumbar degenerative disease are similar to the symptoms of FFP. Case Report: We encountered two cases in which FFP developed during the treatment of lumbar degenerative disease with radiculopathy. Both patients had undergone conservative treatment for lumbar degenerative disease, but their symptoms gradually worsened and they presented with gait disturbance. FFP was diagnosed by imaging, and surgery was required in one case. Both cases showed L3 foraminal stenosis on the image, and the symptoms of L3 radiculopathy presented with thigh pain, hip pain, and knee pain, which is similar to the pain site of FFP. Therefore, diagnosis of FFP was difficult. Conclusion: In lumbar degenerative diseases presenting with radiculopathy, the pain site may be similar to that of FFP, which may make diagnosis of FFP difficult. Therefore, especially in patients with lumbar degenerative disease presenting with L3 radiculopathy, it is necessary to consider the possibility of FFP and perform MRI imaging to make an early diagnosis when the symptoms change.

Effects of the difference between lumbar lordosis in the supine and standing positions on the clinical outcomes of decompression surgery for lumbar spinal stenosis.

OBJECTIVE: The authors sought to evaluate the relationship between the difference in lumbar lordosis (DiLL) in the preoperative supine and standing positions and spinal sagittal alignment in patients with lumbar spinal stenosis (LSS) and to determine whether this difference affects the clinical outcome of laminectomy. METHODS: Sixty patients who underwent single-level unilateral laminectomy for bilateral decompression of LSS were evaluated. Spinopelvic parameters in the supine and standing positions were measured preoperatively and at 3 months and 2 years postoperatively. DiLL between the supine and standing positions was determined as follows: DiLL = supine LL - standing LL. On the basis of this determination patients were then categorized into DiLL(+) and DiLL(-) groups. The relationship between DiLL and preoperative spinopelvic parameters was evaluated using Pearson's correlation coefficient. In addition, clinical outcomes such as visual analog scale (VAS) and Oswestry Disability Index (ODI) scores between the two groups were measured, and their relationship to DiLL was evaluated using two-group comparison and multivariate analysis. RESULTS: There were 31 patients in the DiLL(+) group and 29 in the DiLL(-) group. DiLL was not associated with supine LL but was strongly correlated with standing LL and pelvic incidence (PI) - LL (PI - LL). In the preoperative spinopelvic alignment, LL and SS in the standing position were significantly smaller in the DiLL(+) group than in the DiLL(-) group, and PI - LL was significantly higher in the DiLL(+) group than in the DiLL(-) group. There was no difference in the clinical outcomes 3 months postoperatively, but low-back pain, especially in the sitting position, was significantly higher in the DiLL(+) group 2 years postoperatively. DiLL was associated with low-back pain in the sitting position, which was likely to persist in the DiLL(+) group postoperatively. CONCLUSIONS: We evaluated the relationship between DiLL and spinal sagittal alignment and the influence of DiLL on postoperative outcomes in patients with LSS. DiLL was strongly correlated with PI - LL, and in the DiLL(+) group, postoperative low-back pain relapsed. DiLL can be useful as a new spinal alignment evaluation method that supports the conventional spinal sagittal alignment evaluation.

Predictors of Spontaneous Restoration of Lumbar Lordosis after Single-Level Transforaminal Lumbar Interbody Fusion for Degenerative Lumbar Diseases.

INTRODUCTION: Preoperative factors that predict postoperative restoration of lumbar lordosis (LL) are not well understood. To investigate whether preoperative postural correction of LL, sagittal malalignment, or lumbar flexibility are associated with the postoperative restoration of LL in patients treated with a single-level transforaminal lumbar interbody fusion (TLIF), a retrospective cohort study was conducted. METHODS: We enrolled 104 patients (mean age: 67.5±10.7 years old; 47 men and 57 women) with lumbar degenerative diseases treated with a single-level TLIF. The pre- and postoperative LL were examined using lateral radiographs in the standing position and computed tomography (CT) images in the supine position. The correlation between postoperative LL restoration and preoperative postural correction of LL (difference in LL between the standing and supine positions: D-LL), sagittal imbalance (pelvic incidence minus LL: PI-LL), and lumbar flexibility (difference in LL between the flexion and extension postures) were analyzed. Patients were divided into two groups according to the D-LL (D-LL≥0° and D-LL<0°). The rates of postoperative LL restoration (postoperative LL-preoperative LL in standing) were compared between the two groups. RESULTS: Multiple regression analysis performed after adjustment for age, gender, body mass index, and cage angle revealed that postoperative LL restoration was significantly correlated with D-LL (p<0.001), but not with PI-LL, and lumbar flexibility. Patients with a preoperative D-LL≥0° showed a significantly greater increase of LL after TLIF (7.1°±11.2°) than those with D-LL<0° (1.4°±6.6°) (p=0.003). CONCLUSIONS: A preoperative evaluation of a lateral radiograph or CT taken in the supine position is useful in predicting postoperative improvement of sagittal alignment. Postoperative improvement of sagittal spinopelvic alignment would be expected when LL is corrected in the supine position preoperatively. Surgeons should pay attention to the postural correction of LL when performing short-segment fusion surgery for lumbar degenerative disease with sagittal malalignment.