Relationship between degree of separation of endplate cartilage and severity of intervertebral disc herniation.

Degeneration of intervertebral disc and fissures in the anulus was caused by compression and distraction, which lead to nucleus pulposus herniation. However, controversy remains regarding the exact mechanism behind disc herniation. The aim of this study is to analyze histologically the differences between the three types of disc herniations in an attempt to infer the underlying mechanism. Disc samples extracted from 49 patients who underwent discectomy of the lumbar region were studied by histological analysis. The severity of disc herniation was classified as bulging, protrusion, extrusion, or sequestration based on preoperative magnetic resonance imaging measurements. For comparative analysis of sequestration characteristics, 49 patients were classified into either the sequestration or the non-sequestration group (i.e., protrusion and extrusion) according to disc herniation type. Forty of the 49 patients had cartilage present in their disc samples upon histological analysis. The endplate cartilage-containing samples included two of four (50%) protruded disc patients, 22 of 29 (75.9%) extruded disc patients, and 16 of 16 (100%) sequestrated disc patients and had statistical significance (p = 0.019). There were no significant differences in age, sex, body mass index, length of hospital stays, injection history, surgical methods, and Visual Analog Scale between the sequestration and non-sequestration group (all p > 0.05). Separation of endplate cartilage increased with the severity of disc herniation. Therefore, the mechanism of disc herniation should consider the connection with endplate cartilage as an initiating link in the mechanical failure of intervertebral discs.

Validation and cross-cultural adaptation of the Korean version of the Core Outcome Measures Index in patients with degenerative lumbar disease.

PURPOSE: To translate and cross-culturally adapt the Core Outcome Measures Index (COMI) into the Korean language and to test the psychometric properties of the Korean COMI in patients with degenerative lumbar spine diseases. METHODS: A cross-cultural adaptation of the COMI into Korean was carried out using established guidelines. A total of 117 patients with lumbar spinal diseases were recruited from the spinal center of a tertiary care teaching institution and completed a baseline questionnaire including the newly translated COMI, the visual analog scale for back pain and for leg pain, the Oswestry Disability Index (ODI), and the EuroQOL-5 dimensions (EQ-5D). Within 2 weeks after the first assessment, 83 (71%) completed a second COMI questionnaire and a transition question (no change, slight change, moderate change, a lot of change) by phone to assess reproducibility. RESULTS: COMI summary scores displayed 1.7% floor effects and no ceiling effect. For construct validity, each COMI item and COMI summary score well correlated with its corresponding reference questionnaire. Therefore, the predefined hypotheses for the construct validities of each COMI item (ρ > 0.4 with the corresponding questionnaire) and the COMI summary score (ρ > 0.6 with both ODI and EQ-5D) were confirmed. Intraclass correlation coefficients of each COMI item and summary score ranged from 0.93 to 0.98. Therefore, the hypothesis for reliability (ICC > 0.8) was confirmed. CONCLUSIONS: The present study highlights that the Korean version of the COMI is a reliable and valid outcome tool for use in Korean-speaking patients with degenerative lumbar spinal disease. These slides can be retrieved under Electronic Supplementary Material.

Comparative study of the efficacy of transdermal buprenorphine patches and prolonged-release tramadol tablets for postoperative pain control after spinal fusion surgery: a prospective, randomized controlled non-inferiority trial.

PURPOSE: To compare the efficacy of a transdermal buprenorphine patch (5, 10, 15, and 20 µg/h) with that of oral tramadol (150, 200, 250, and 300 mg) for postoperative pain control after single level spinal fusion surgery. METHODS: The present study (ClinicalTrials.gov, number NCT02416804) was a prospective, randomized controlled non-inferiority trial designed to determine the efficacy of buprenorphine TDS for alleviating postoperative pain following patient controlled analgesia (PCA) in persons underwent a single level posterior lumbar interbody fusion surgery through 1:1 allocation. The primary outcome was the Visual Analog Pain Scale (VAS) score for postoperative back pain at 7 days after surgery. The non-inferior margin of the VAS was set at δ = 1.5 points. RESULTS: The VAS score (primary outcome) for postoperative back pain at 7 days after surgery in the Buprenorphine group was not inferior compared to the Tramadol group. The overall changes in VAS scores for postoperative pain during follow-up assessments over a 2-week period did not differ between both groups. However, the VAS scores for postoperative pain significantly improved with time after surgery in both groups. The patterns of changes in the VAS scores for postoperative pain during the follow-up period were not significantly different between the both groups. CONCLUSIONS: The efficacy of buprenorphine TDS was not inferior to that of oral tramadol medication for alleviating postoperative pain in the subacute period from 72 h after surgery, following PCA administration. In addition, adverse events were similar between both groups.

Fusion Length Requiring Spinopelvic Fixation in Lumbosacral Fusion with Anterior Column Support at L5-S1: Assessment of Fusion Status Using Computed Tomography.

Background: The lumbosacral (LS) junction has a higher nonunion rate than other lumbar segments, especially in long-level fusion. Nonunion at L5-S1 would result in low back pain, spinal imbalance, and poor surgical outcomes. Although anterior column support at L5-S1 has been recommended to prevent nonunion in long-level LS fusion, fusion length requiring additional spinopelvic fixation (SPF) in LS fusion with anterior column support at L5-S1 has not been evaluated thoroughly. This study aimed to determine the number of fused levels requiring SPF in LS fusion with anterior column support at L5-S1 by assessing the interbody fusion status using computed tomography (CT) depending on the fusion length. Methods: Patients who underwent instrumented LS fusion with L5-S1 interbody fusion without additional augmentation and CT > 1 year postoperatively were included. The fusion rates were assessed based on the number of fused segments. Patients were divided into two groups depending on the L5-S1 interbody fusion status: those with union vs. those with nonunion. Binary logistic regression analyses were performed to identify risk factors for LS junctional nonunion. Results: Fusion rates of L5-S1 interbody fusion were 94.9%, 90.3%, 80.0%, 50.0%, 52.6%, and 43.5% for fusion of 1, 2, 3, 4, 5, and ≥ 6 levels, respectively. The number of spinal levels fused ≥ 4 (p < 0.001), low preoperative bone mineral density (BMD; adjusted odds ratio [aOR], 0.667; p = 0.035), and postoperative pelvic incidence (PI) - lumbar lordosis (LL) mismatch (aOR, 1.034; p = 0.040) were identified as significant risk factors for nonunion of L5-S1 interbody fusion according to the multivariate logistic regression analysis. Conclusions: Exhibiting ≥ 4 fused spinal levels, low preoperative BMD, and large postoperative PI-LL mismatch were identified as independent risk factors for nonunion of anterior column support at L5-S1 in LS fusion without additional fixation. Therefore, SPF should be considered in LS fusion extending to or above L2 to prevent LS junctional nonunion.

Learning Curve for Minimally Invasive Scoliosis Surgery in Adolescent Idiopathic Scoliosis.

OBJECTIVE: To evaluate the learning curve of minimally invasive scoliosis surgery (MISS) in patients with adolescent idiopathic scoliosis (AIS). METHODS: A total of 76 AIS patients who underwent MISS were included from March 2015 to February 2017. The cases were divided chronologically into early period group (Group A, March 2015-February 2016, n = 31) and late period group (Group B, March 2016-February 2017, n = 45). Radiological parameters, operative parameters, and clinical outcomes were included in this study. The selected criteria for receiver operating characteristic analysis used to assess learning curve were mean operative time (≤389 minutes) and estimated blood loss (EBL) (≤948 mL). RESULTS: The mean operative time was 389 minutes, and the EBL was 948 mL. The mean operative time was significantly reduced in the late period group (360 minutes) compared to the early period group (431 minutes) (P < 0.005). The mean EBL was significantly reduced for the late period group (798 mL) compared to the early period group (1164 mL) (P < 0.001). Forty-six cases were required to achieve the preset criteria (area under the curve 0.858; P < 0.001; sensitivity 0.778; specificity 0.796). CONCLUSIONS: A mild learning curve was demonstrated in MISS for AIS with significant improvement in operative times and EBL over time. Experience of more than 46 cases of MISS was required to obtain proficient surgical skills for a trained surgeon of conventional open scoliosis surgery.

Impact on Spine Surgery during the First Two Years of COVID-19 Pandemic: A Nationwide Study in South Korea.

Since December 2019, the novel coronavirus (COVID-19) has infected people worldwide. Owing to its rapid spread, elective surgeries, including spine surgery, have been re-scheduled. We analyzed nationwide data to investigate changes in the volume of spine surgery during the first two years of the pandemic. Nationwide data from January 2016 to December 2021 were obtained. We compared the total number of patients who underwent spine surgery and related medical expenses before and during the COVID-19 pandemic. In February and September, the number of patients was significantly smaller compared to January and August, respectively. Despite the pandemic, the proportion of patients undergoing spine surgery for degenerative diseases in 2021 was the highest. In contrast, the proportions of patients undergoing spine surgery for tumors showed a continuous decrease from 2019 to 2021. Although the number of spine surgeries performed at tertiary hospitals was lowest in 2020, it was not significantly smaller than that in 2019.The number of patients who underwent spine surgery in March 2020, during the first outbreak, decreased compared to the previous month, which differed from the trend observed in the pre-COVID-19 period. However, as the pandemic continues, the impact of COVID-19 on spine surgery has become less evident.

Long-term Outcomes of Posterior Multilevel Crack Osteotomy: Revisional Surgery for Scoliosis With a Fusion Mass.

OBJECTIVE: Osteotomies are required for the mobilization of spinal segments in patients with revisional scoliosis surgery with a fusion mass; however, only a few techniques have shown efficacy and safety, and their mid- and long-term outcomes remain unelucidated. This study aimed to analyze long-term outcomes of the posterior multilevel crack osteotomy (PMCO) technique for revisional surgery for scoliosis with a fusion mass. METHODS: Data from 18 patients who underwent revisional scoliosis surgery using PMCO between 2009 and 2015 and had more than 5-year follow-up were retrospectively reviewed. The Cobb angle and coronal and sagittal balance parameters were examined preoperatively, postoperatively, and during the final follow-up. Perioperative parameters and complications were also assessed. RESULTS: Preoperative and postoperative Cobb angles were 60.5° and 29.9°, respectively (p < 0.001); this improvement was maintained until the final follow-up (33.4°, p = 0.058). The difference in preoperative and postoperative coronal balance was statistically significant (15.9 mm and 9.2 mm, respectively; p < 0.001); this was maintained until the final follow-up (p = 0.071). There was no change in sagittal balance parameters over the 3 measurement periods. Only 1 patient showed PMCO-related motor weakness, but he spontaneously recovered 3 months after postsurgery. Pseudarthrosis was not observed during the follow-up period. CONCLUSION: Incomplete osteotomy using PMCO provided satisfactory deformity correction without severe complications during revisional surgery for scoliosis with a fusion mass. It may be a less invasive procedure that maintains cortical continuity, preserves soft tissues, and provides sufficient mobility for the correction of spinal segments.

Clinical and radiological efficacy of spino-pelvic fixation in the treatment of neuromuscular scoliosis.

Pelvic fixation is performed to obtain proper coronal and sagittal alignment when the pelvic obliquity is more than 15º in patients with neuromuscular scoliosis (NMS). Since many NMS patients were wheelchair or bed-ridden status, there has been controversy on the effect of pelvic fixation. Therefore, the purpose of this study is to analyze the effects of pelvic fixation on correction of spinal deformity and quality of life (QoL) in NMS patients. A total of 77 NMS patients who underwent deformity correction were divided into three groups and retrospectively analyzed preoperatively, postoperatively, and at 2-year follow-up: pelvic fixation group (Group A, n = 16), fixed to S1 (Group B, n = 33), and fixed to L5 (Group C, n = 28). The correction rate of scoliosis was 60.0%, 58.0%, and 56.7% in groups A, B, and C, respectively, with no statistical difference (P > 0.05). The correction rate of pelvic obliquity was 61.3%, 42.8%, and 57.5% in respective groups A, B, and C, with no significance (P > 0.05). The correction loss of scoliosis and pelvic obliquity showed no statistical significance between three groups for 2-year follow-up (all Ps > 0.05). There were no significant differences regarding clinical outcomes and postoperative complications among the three groups (all Ps > 0.05). Therefore, pelvic fixation using iliac screws is not substantially influencing radiological and clinical outcomes in the patients with NMS.

The Accuracy and Safety of a Pedicle Screw Using the Freehand Technique in Minimally Invasive Scoliosis Surgery.

OBJECTIVE: The safety and clinical usefulness of minimally invasive scoliosis surgery (MISS) has been reported in various studies. However, freehand pedicle screwing in MISS remains technically challenging. The purpose of this study is to evaluate the accuracy and safety of pedicle screw placement using the freehand technique in adolescent idiopathic scoliosis (AIS) patients treated with MISS compared to conventional open scoliosis surgery (COSS). METHODS: We included 76 patients who underwent deformity correction for AIS. Computed tomography scans were used to assess screw violations divided into 2 groups according to the surgical technique: MISS or COSS. Anterior violations were classified into grade 0, 1 (no contact with internal organs), and 2 (contact with internal organs). Medial and lateral violations were classified into grade 0, 1 ( < 2 mm), and 3 ( ≥ 2 mm). grade 2 were considered critical violations. RESULTS: A total of 630 and 1,174 pedicle screws were inserted in the MISS and COSS groups, respectively. The overall critical violation rates of the MISS and COSS groups were 16.8% (106 screws) and 14.0% (165 screws) (p = 0.116). Medial critical violations on the left side in the middle thoracic region frequently occurred in the MISS group compared to the COSS group (p = 0.003). There were no statistical differences in the complications. CONCLUSION: Pedicle screw placement using the freehand technique in MISS for AIS patients provided similar accuracy and safety compared to COSS. Pedicle screws inserted on the left side of the middle thoracic region, exhibited more medial critical violations in the MISS group.

Safe Optimal Tear Drop View for Spinopelvic Fixation Using a Three-Dimensional Reconstruction Model of the Pelvis.

Background: Spinopelvic fixation (SPF) has been a challenge for surgeons despite the advancements in instruments and surgical techniques. C-arm fluoroscopy-guided SPF is a widely used safe technique that utilizes the tear drop view. The tear drop view is an image of the corridor from the posterior superior iliac spine to the anterior inferior iliac spine (AIIS) of the pelvis. This study aimed to define the safe optimal tear drop view using three-dimensional reconstruction of computed tomography images. Methods: Three-dimensional reconstructions of the pelvises of 20 individuals were carried out. By rotating the reconstructed model, we simulated SPF with a cylinder representing imaginary screw. The safe optimal tear drop view was defined as the one embracing a corridor with the largest diameter with the inferior tear drop line not below the acetabular line and the lateral tear drop line medial to the AIIS. The distance between the lateral border of the tear drop and AIIS was defined as tear drop index (TDI) to estimate the degree of rotation on the plane image. Tear drop ratio (TDR), the ratio of the distance between the tear drop center and the AIIS to TDI, was also devised for more intuitive application of our simulation in a real operation. Results: All the maximum diameters and lengths were greater than 9 mm and 80 mm, respectively, which are the values of generally used screws for SPF at a TDI of 5 mm and 10 mm in both sexes. The TDRs were 3.40 ± 0.41 and 3.35 ± 0.26 in men and women, respectively, at a TDI of 5 mm. The TDRs were 2.26 ± 0.17 and 2.14 ± 0.12 in men and women, respectively, at a TDI of 10 mm. Conclusions: The safe optimal tear drop view can be obtained with a TDR of 2.5 to 3 by rounding off the measured values for intuitive application in the actual surgical field.

Characteristics of Patients Undergoing Surgical Treatment for Spinal Metastases From Colorectal Cancer: A Comparison With Non-Small Cell Lung Cancer.

STUDY DESIGN: This was a retrospective study. OBJECTIVE: This study aimed to investigate the prognosis and characteristics of patients undergoing surgical treatment for colorectal cancer (CRC) spinal metastasis. To better understand the characteristics of such patients, their results were compared with those with spinal metastasis from non-small cell lung cancer (NSCLC), as the prognosis of these patients is well-studied. SUMMARY OF BACKGROUND DATA: CRC commonly metastasizes to the liver or lung, while spinal metastases occur infrequently. The literature contains very few studies evaluating the prognosis of patients with spinal metastases from CRC. MATERIALS AND METHODS: A consecutive 155 patients who underwent surgical treatment for spinal metastases from CRC (n=35) or NSCLC (n=120) between 2010 and 2018 were included in this study. Data were collected throughout the disease course, including those concerning all cancer-related treatments for both the primary cancer and spinal metastasis. Categorical variables were divided into patient, tumor, and treatment factors, and postoperative survival times were compared between the CRC and NSCLC groups. RESULTS: The mean interval from cancer diagnosis to spinal metastasis was significantly greater in CRC group (32.5 mo) than in NSCLC group (12.9 mo). Concurrent spinal metastasis was more common in NSCLC group than CRC group (45.0% vs. 17.2%; P=0.003). Visceral metastasis was found more frequently in CRC group than NSCLC group (77.1% vs. 42.5%; P<0.001). The proportion of patients undergoing postoperative systemic treatment was significantly higher in NSCLC group than CRC group (59.2% vs. 20.0%; P<0.001). Median survival time after spine surgery was 4.2 months in CRC group and 5.8 months in NSCLC group (P=0.015). CONCLUSIONS: The prognosis after surgical treatment for CRC spinal metastasis was poor, and worse than that of NSCLC group. These results can be explained by the later development of spinal metastases and the limited chance of postoperative medical treatment in CRC spinal metastasis.

The Efficacy of Single-Stage Correction by Posterior Approach for Neglected Congenital Scoliosis: Comparative Analysis According to the Age of Surgical Intervention.

Background: A single-stage correction for congenital scoliosis through a posterior-only approach is a commonly used surgical technique. However, there are few studies on the surgical treatment effect of posterior single-stage correction in patients with neglected congenital scoliosis. Methods: Patients who underwent a single-stage posterior correction for congenital scoliosis with a minimum follow-up of 2 years were divided into three groups based on age: Group A (7−11 years), B (12−18 years) and C (>18 years). A comparison of surgical, radiological, and clinical outcomes was performed for three groups. Results: The Cobb angle changed form 75 ± 18° to 37 ± 18° with a correction rate of 53%. Group A showed a significantly higher correction rate than Group B and C (all p < 0.001). The amount of blood loss in Groups B and C was significantly larger than that of Group A (p = 0.015). Pulmonary complications were significantly higher in Group C (p = 0.007). Conclusions: A single-stage correction with pedicle screws through a posterior-only approach achieved a significant correction with improved outcomes, even in neglected cases. However, the early correction for younger patients was still more beneficial in terms of bleeding loss, complications, and flexible curve correction.

Adult Spinal Deformity: A Comprehensive Review of Current Advances and Future Directions.

Owing to rapidly changing global demographics, adult spinal deformity (ASD) now accounts for a significant proportion of the Global Burden of Disease. Sagittal imbalance caused by age-related degenerative changes leads to back pain, neurological deficits, and deformity, which negatively affect the health-related quality of life (HRQoL) of patients. Along with the recognized regional, global, and sagittal spinopelvic parameters, poor paraspinal muscle quality has recently been acknowledged as a key determinant of the clinical outcomes of ASD. Although the Scoliosis Research Society-Schwab ASD classification system incorporates the radiological factors related to HRQoL, it cannot accurately predict the mechanical complications. With the rapid advances in surgical techniques, many surgical options for ASD have been developed, ranging from minimally invasive surgery to osteotomies. Therefore, structured patient-specific management is important in surgical decision-making, selecting the proper surgical technique, and to prevent serious complications in patients with ASD. Moreover, utilizing the latest technologies such as robotic-assisted surgery and machine learning, should help in minimizing the surgical risks and complications in the future.

Novel Surgical Technique for Adolescent Idiopathic Scoliosis: Minimally Invasive Scoliosis Surgery.

Despite advancements in instruments and surgical techniques for adolescent idiopathic scoliosis (AIS) surgery, conventional open scoliosis surgery (COSS) is usually required to achieve satisfactory deformity correction using various distinct surgical techniques, such as rod derotation, direct vertebral rotation, facetectomies, osteotomies, and decortication of the laminae. However, COSS is accompanied by significant blood loss and requires a large midline skin incision. Minimally invasive surgery (MIS) has evolved enormously in various fields of spinal surgery, including degenerative spinal diseases. MIS of the spine has some advantages over conventional surgery, such as a smaller incision, less blood loss and postoperative pain, and lower infection rates. Since the introduction of MIS for AIS in 2011, MIS has been reported to have comparable outcomes, including correction rate with some usual advantages of MIS. However, several complications, such as dislodgement of rods, wound infection, and hypertrophic scar formation, have also been reported in the initial stages of MIS for AIS. We devised a novel approach, called the coin-hole technique or minimally invasive scoliosis surgery (MISS), to minimize these complications. This article aimed to introduce a novel surgical technique for AIS and provide a preliminary analysis and up-to-date information regarding MISS.

The Long-term Fate of Asymptomatic Proximal Junctional Kyphosis Following Long Instrumented Fusion in Elderly Patients with Sagittal Imbalance.

STUDY DESIGN: Retrospective study. OBJECTIVE: The aim of this study was to investigate the long-term fate of asymptomatic PJK focusing on the elderly patients with sagittal imbalance by comparing the patients with and without PJK. SUMMARY OF BACKGROUND DATA: Most of previous studies demonstrated that PJK does not negatively affect the clinical outcome compared to that of the patients without PJK. The question "will the asymptomatic PJK remain asymptomatic even in long-term follow-up?" has not been answered yet because the previous results were based on the short follow-up duration. METHODS: Patients >60 years who underwent four or more level fusions to the sacrum for sagittal imbalance were followed up for >5 years. The radiographic and clinical outcomes were compared between PJK (n = 30) and non-PJK groups (n = 43). PJK was defined by proximal junctional angle (PJA) >10°. Only patients with >3 years of follow-up duration after PJK development were included in PJK group. The clinical outcome measures included visual analog scale (VAS) for the back and leg, Oswestry disability index (ODI), and Scoliosis Research Society (SRS)-22 scores. RESULTS: The mean age was 69.2 years. Total follow-up duration was 92.4 months. Time between PJK development and the last follow-up was 67.4 months in PJK group. Although there were no differences between the two groups in terms of pelvic incidence-lumbar lordosis mismatch, pelvic tilt, or sacral vertical axis, PJA significantly increased from 6.5° postoperatively to 21.2° at the final follow-up in the PJK group. The clinical outcomes were worse (such as VAS for the back, ODI, and SRS-22 scores) in the PJK group than in non-PJK group, except for the satisfaction domain. Three (10%) of 30 patients underwent a revision surgery for PJK progression. CONCLUSION: Even if PJK was asymptomatic at initial development, it progressed radiographically with time and eventually gave a negative impact on the clinical outcomes in long-term follow-up.Level of Evidence: 3.

Who Will Require Revision Surgery Among Neurologically Intact Patients with Proximal Junctional Failure After Surgical Correction of Adult Spinal Deformity?

STUDY DESIGN: Retrospective study. OBJECTIVE: To identify the risk factors for revision surgery among neurologically intact patients with proximal junctional failure (PJF) after adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: PJF following long fusion for ASD is a well-recognized complication that negatively affects clinical outcomes. However, revision surgery is not required for every patient with PJF especially if the patient does not present with neurologic deficit. Identifying the risk factors of revision surgery is necessary to determine who will need revision surgery as well as when is the right time for the revision surgery. METHODS: Sixty-nine neurologically intact patients with PJF following ASD surgery were followed up with more than 2 years after PJF development or until undergoing revision surgery. PJF was divided into ligamentous failure (proximal junctional angle [PJA] of more than 20°) and bony failure. According to the conduct of revision surgery, two groups (revision and no revision) were created. Risk factors for revision surgery were analyzed in univariate and multivariate analysis with regard to patient, surgical and radiographic variables. RESULTS: The mean age at the time of PJF development was 70.9 years. There were 45 patients with bony failure and 24 with ligamentous failure. Revision surgery was performed for 23 patients (33.3%). Multivariate analysis revealed that bony failure (odds ratio: 10.465) and PJA (odds ratio: 1.131) were significant risk factors. For those with bony failure, the cutoff value of PJA for performing revision surgery was calculated as 22°. The revision rate was significantly highest in patients (63.6%) with bony failure + PJA 22° or higher followed by patients (26.1%) with bony failure + PJA less than 22° and patients (12.5%) with ligamentous failure (P = 0.002). CONCLUSION: Bony failure with PJA of greater than 22° increased the likelihood for revision surgery. Therefore, early surgical intervention should be considered in these patients.Level of Evidence: 4.

Failure Types and Related Factors of Spinopelvic Fixation After Long Construct Fusion for Adult Spinal Deformity.

BACKGROUND: Rigid internal fixation of the spine is an essential part of adult spinal deformity (ASD) surgery. Despite the use of pelvic fixation and anterior column support, spinopelvic fixation failure (SPFF) still remains an issue. Few studies have evaluated the types of such failure or its related factors. OBJECTIVE: To classify the types of SPFF and investigate its risk factors, including the fusion status at L5-S1 on CT scan. METHODS: The study cohort consisted of ninety-eight ASD patients who underwent more than 4-level fusions to the sacrum with interbody fusion at L5-S1. Patients with SPFF were divided into the two groups: above-S1 and below-S1 failure groups. The patient, surgical, and radiographic variables in each group were compared to those of the no-failure group. The L5-S1 fusion status was assessed using 2-yr computed tomography (CT) scan. Univariate and multivariate analyses were performed to determine the risk factors for each failure group. RESULTS: The mean age was 68.5 yr. Follow-up duration was 55.7 mo. The SPFF developed in 46 (46.9%) patients at 32.7 mo postoperatively. There were 15 patients in the above-S1 failure group and 31 patients in the below-S1 failure group. Multivariate analysis revealed that nonunion at L5-S1 was a single risk factor for above-S1 failure. In contrast, the risk factors for below-S1 failure included a greater number of fused segments and postoperative less thoracic kyphosis. CONCLUSION: SPFF develops in different patterns with different risk factors. Above-S1 SPFF was associated with nonunion at L5-S1, while below-S1 SPFF was associated with mechanical stress.

Long-Term Influence of Paraspinal Muscle Quantity in Adolescent Idiopathic Scoliosis Following Deformity Correction by Posterior Approach.

Pedicle screw instrumentation (PSI) through posterior approach has been the mainstay of deformity correction for adolescent idiopathic scoliosis (AIS). However, changes in the quantity of paraspinal muscles after AIS surgery has remained largely unknown. The aim of this study was to investigate long-term follow-up changes in paraspinal muscle volume in AIS surgery via a posterior approach. Forty-two AIS patients who underwent deformity correction by posterior approach were analyzed through a longitudinal assessment of a cross-sectional area (CSA) in paraspinal muscles with a minimum five-year follow-up. The CSA were measured using axial computed tomography images at the level of the upper endplate L4 by manual tracing. The last follow-up CSA ratio of the psoas major muscle (124.5%) was significantly increased compared to the preoperative CSA ratio (122.0%) (p < 0.005). The last follow-up CSA ratio of the multifidus and erector spine muscles significantly decreased compared to the preoperative CSA ratio (all p < 0.005). The CSA ratio of the erector spine muscle was correlated with the CSA ratio of the psoas major (correlation coefficient = 0.546, p < 0.001). Therefore, minimizing the injury to the erector spine muscle is imperative to maintaining psoas major muscle development in AIS surgery by posterior approach.

Long-term benefits of appropriately corrected sagittal alignment in reconstructive surgery for adult spinal deformity: evaluation of clinical outcomes and mechanical failures.

OBJECTIVE: It has been well documented that optimal sagittal alignment is highly correlated with good clinical outcomes in adult spinal deformity (ASD) surgery. However, it remains to be determined whether the clinical benefit of appropriately corrected sagittal alignment can be maintained in the long term. Therefore, the aim of this study was to investigate whether appropriately corrected sagittal alignment continues to offer benefits over time with regard to clinical outcomes and mechanical failure. METHODS: Patients older than 50 years who underwent ≥ 4-level fusion for ASD and were followed up for ≥ 5 years were included in this study. Appropriateness of sagittal alignment correction was defined as pelvic incidence minus lumbar lordosis ≤ 10°, pelvic tilt ≤ 25°, and sagittal vertical axis ≤ 50 mm. Two groups were created based on this appropriateness: group A (appropriate) and group IA (inappropriate). Clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry Disability Index (ODI), and Scoliosis Research Society Outcomes Questionnaire-22 (SRS-22). The development of mechanical failures, such as rod fracture and proximal junctional kyphosis (PJK), was compared between the two groups. RESULTS: The study included 90 patients with a follow-up duration of 90.3 months. There were 30 patients in group A and 60 patients in group IA. The clinical outcomes at 2 years were significantly better in group A than in group IA in terms of the VAS scores, ODI scores, and all domains of SRS-22. At the final follow-up visit, back VAS and ODI scores were still lower in group A than they were in group IA, but the VAS score for leg pain did not differ between the groups. The SRS-22 score at the final follow-up showed that only the pain and self-image/appearance domains and the total sum were significantly higher in group A than in group IA. The incidence of rod fracture and PJK did not differ between the two groups. The rate of revision surgery for rod fracture or PJK was also similar between the two groups. CONCLUSIONS: The clinical benefits from appropriate correction of sagittal alignment continued for a mean of 90.3 months. However, the intergroup difference in clinical outcomes between groups A and IA decreased over time. The development of rod fracture or PJK was not affected by the appropriateness of sagittal alignment.

Clinical Significance of Radiologic Improvement Following Single-Level Oblique Lateral Interbody Fusion With Percutaneous Pedicle Screw Fixation.

Indirect decompression using oblique lateral interbody fusion (OLIF) improves spinal canal dimensions by reducing spondylolisthesis and restoring intervertebral disk height in patients with degenerative lumbar diseases. However, the clinical significance of these radiological improvements has not been fully evaluated in the literature. To examine the relationship between the clinical and radiological outcomes following OLIF, the authors prospectively studied 41 patients who underwent single-level OLIF with percutaneous pedicle screw fixation for lumbar degenerative disease, including degenerative and spondylolytic spondylolisthesis and spinal stenosis with disk height loss. Clinical scores were obtained preoperatively and at 1 year postoperatively using multiple questionnaires. Radiological outcomes were evaluated using plain radiographs, computed tomography (CT) scans, and magnetic resonance imaging (MRI) at 1 year postoperatively. Following a single-level OLIF, all categories of clinical scores showed statistically significant improvement. Rate of cage subsidence was 14.6% and 31.7% at 1 week and 1 year postoperatively, respectively. Patients with subsidence had higher Oswestry Disability Index (P=.026) scores and lower physical composite summary scores on the Short Form-36 Health Survey (P=.007). On CT scan, 28 (68.3%) patients showed a complete interbody fusion and 13 (31.7%) had intermediate fusion. All parameters from the MRI, except for foraminal width, showed significant improvement at 1 year postoperatively. The improvement ratio of foraminal height was associated with the percent improvement of lower-extremity radiating pain (Pearson coefficient=0.384; P=.013) and the walking ability score of the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (Pearson coefficient=0.319; P=.042) at 1 year postoperatively. Restoration of foraminal height while preserving the endplates is associated with favorable results following OLIF. [Orthopedics. 2020;43(4):e283-e290.].