Narrative Review of Clinical Impact of Head-Hip Offset Following Adult Spinal Deformity Surgery

In adult spinal deformity (ASD) surgery, mechanical failure (MF) has been a significant concern for spine surgeons as well as patients. Despite earnest endeavors to prevent MF, the absence of a definitive consensus persists, owing to the intricate interplay of multifarious factors associated with this complication. Previous approaches centered around global spinal alignment have yielded limited success in entirely forestalling MF. These methodologies, albeit valuable, exhibited limitations by neglecting to encompass global balance and compensatory mechanisms within their purview. In response to this concern, an in-depth comprehension of global balance and compensatory mechanisms emerges as imperative. In this discourse, the center of gravity and the gravity line are gaining attention in recent investigations pertaining to global balance. This narrative review aims to provide an overview of the global balance and a comprehensive understanding of related concepts and knowledge. Moreover, it delves into the clinical ramifications of the contemporary optimal correction paradigm to furnish an encompassing understanding of global balance and the current optimal correction strategies within the context of ASD surgery. By doing so, it endeavors to furnish spine surgeons with a guiding compass, enriching their decision-making process as they navigate the intricate terrain of ASD surgical interventions.

Diagnosis and treatment of adult spinal deformity

The diagnosis rate of adult spinal deformity (ASD) is increasing with increased life expectancy and the prevalence of degenerative spinal diseases. The prevalence of ASD in adults aged >60 years has been reported to be up to 68%. ASD has significant impact on the pain, disability, and mental health. Therefore, it is necessary to establish an effective surgical plan by accumulating modern knowledge on ASD, developing surgical techniques, and improving pre- and post-operative care so as to achieve optimal surgical outcomes.Current Concepts: ASD results from coronal and sagittal malalignments caused by degenerative diseases or iatrogenic factors. Recently, the significance of sagittal alignment correction has been emphasized, and the SRSSchwab classification of ASD is generally accepted. Individualized correction goals can be set through sufficient preoperative evaluations and imaging studies, and appropriate coronal and sagittal alignment correction can be achieved through intraoperative positioning of patient, anterior and posterior approach spine surgery, screw fixation, and osteotomies.Discussion and Conclusion: It is necessary to establish an optimal correction target and select the appropriate surgical approach for each patient with ASD, so as to improve patients’ quality of life. Surgical interventions for ASD can be safely completed by adequately comprehending and anticipating perioperative complications.

Reciprocal Changes in the Whole-Body Following Realignment Surgery in Adult Spinal Deformity

The idea of the global balance of spine stems from Jean Dubousset, who first introduced the concept of cone of economy. Through the compensatory mechanisms, the human body maintains an upright posture and horizontal gaze in the setting of the spinal malalignment. Compensation takes place not only in the mobile spine segments, but also in the pelvis and lower extremities. Patients with a malalignment exhibit compensatory changes in the cervical hyper-lordosis, posterior pelvic shift, knee/ankle flexion, hip extension, and the pelvic retroversion. The advent of whole-body stereo radiography has yielded an improved understanding of global changes among the patients. Deformity-induced compensatory changes in the sagittal alignment could be resolved reciprocally after the surgical correction of the malalignment. Thoracolumbar realignment surgery restores the pathologic compensatory changes in the unfused spinal segments, pelvis, and the lower extremities. Similarly, reciprocal changes in the thoracolumbar spine may harmonize global sagittal alignment after the cervical reconstruction. This study reviews the compensatory mechanisms and reciprocal changes in global sagittal alignment caused by the surgical correction and highlights, the factors that should be considered while assessing a patient’s compensatory status.

Evaluation of the efficacy and safety of epidural steroid injection using a nonparticulate steroid, dexamethasone or betamethasone:a double-blind, randomized, crossover, clinical trial

Background@#The U.S. Food and Drug Administration has prohibited epidural steroid injection (ESI) with particulate steroids. Thus, this study aimed to compare the efficacy and safety of ESI with two nonparticulate steroids, dexamethasone and betamethasone. @*Methods@#The eligible patients (n = 600) who received ESI (0 week) with dexamethasone (ESI-dexa) or betamethasone (ESI-beta) had follow-up visits at 2, 4, and 8 weeks with a phone interview at 12 weeks. The primary endpoint was the proportion of effective responders without pain or who were much improved at 2 weeks. The secondary endpoints were the proportion of crossover injections at 2 weeks; changes in the visual analog scale (VAS) and disability index scores at 2, 4, and 8 weeks; the number of additional ESIs in 12 weeks; the number of participants having spinal surgery, as well as the incidence of adverse events over the 12 weeks. @*Results@#The proportion of effective responders at 2 weeks was not different between ESI-beta (72/216, 33.3%) and ESI-dexa (63/200, 31.5%; P = 0.670). Adverse events were more common with ESI-dexa (40/200, 20.0%) than with ESI-beta (24/216, 11.1%; P = 0.012). VAS scores decreased more with ESI-beta than with ESI-dexa at 2 weeks (difference, 0.35; P = 0.023) and 4 weeks (difference, 0.42; P = 0.011). The disability score improved significantly more with ESI-beta compared with ESI-dexa at 2 weeks (difference, 3.37; P = 0.009), 4 weeks (difference, 4.01; P = 0.002), and 8 weeks (difference, 3.54; P = 0.007). @*Conclusions@#Betamethasone would be more appropriate for ESI.

Systematic Review of Reciprocal Changes after Spinal Reconstruction Surgery : Do Not Miss the Forest for the Trees

The purpose of this review was to synthesize the research on global spinal alignment and reciprocal changes following cervical or thoracolumbar reconstruction surgery. We carried out a search of PubMed, EMBASE, and Cochrane Library for studies through May 2020, and ultimately included 11 articles. The optimal goal of a truly balanced spine is to maintain the head over the femoral heads. When spinal imbalance occurs, the human body reacts through various compensatory mechanisms to maintain the head over the pelvis and to retain a horizontal gaze. Historically, deformity correction has focused on correcting scoliosis and preventing scoliotic curve progression. Following substantial correction of a spinal deformity, reciprocal changes take place in the flexible segments proximal and distal to the area of correction. Restoration of lumbar lordosis following surgery to correct a thoracolumbar deformity induces reciprocal changes in T1 slope, cervical lordosis, pelvic shift, and lower extremity parameters. Patients with cervical kyphosis exhibit different patterns of reciprocal changes depending on whether they have head-balanced or trunk-balanced kyphosis. These reciprocal changes should be considered to in order to prevent secondary spine disorders. We emphasize the importance of evaluating the global spinal alignment to assess postoperative changes.

Surgical Impacts of Metastatic Nonsmall Cell Lung Cancer to the Thoracic and Lumbar Spine

Background@#Surgery for spinal metastasis is rapidly increasing in frequency with procedures ranging from laminectomy to spondylectomy combined with stabilization. This study investigated the effect of various surgical procedures for spinal metastasis of non-small cell lung cancer (NSCLC). @*Methods@#A single-center consecutive series of patients who underwent surgery for spinal metastasis of NSCLC were retrospectively reviewed. Patients' characteristics, radiographic parameters, operative data, clinical outcomes, and complications were analyzed. Surgical outcomes were assessed according to pain and performance status before and after surgery.Overall survival (OS) rate was estimated using the Kaplan-Meier method. Multivariate analysis was performed to detect factors independently associated with OS using a Cox proportional hazards model. @*Results@#Twenty-one patients were treated with laminectomy, 24 with corpectomy, 13 with spondylectomy (piecemeal or total en bloc fashion), and all procedures were combined with stabilization. Back pain and performance status improved significantly after surgical treatment among the three groups. Revision surgery due to tumor progression at the index level or spinal metastasis at another level were four patients (19.0%) in the laminectomy group, six patients (25.0%) in the corpectomy group, and one patient (7.7%) in the spondylectomy group. A Charlson comorbidity index and the number of spinal metastasis negatively affected OS (hazard ratio [HR], 19.613 and 2.244). Postoperative chemotherapy, time to metastasis, spondylectomy, and corpectomy had favorable associations with OS (HR, 0.455, 0.487, 0.619, and 0.715, respectively). @*Conclusion@#Postoperative chemotherapy was the most critical factor in OS of patients with metastatic NSCLC to the spine. An extensive surgical procedure (corpectomy/ spondylectomy) with stabilization also could be beneficial for limited patients with spinal metastasis of NSCLC.

Selection of Fusion Level for Adolescent Idiopathic Scoliosis Surgery : Selective Fusion versus Postoperative Decompensation

Adolescent idiopathic scoliosis (AIS), which is associated with an extensive range of clinical and radiological presentations, is the one of the most challenging spinal disorders. The goals of surgery are to correct the deformity in 3 dimensions and to preserve motion segments while avoiding complications. Despite the ongoing evolution of classification systems and algorithms for the surgical treatment of AIS, there has been considerable debate regarding the selection of an appropriate fusion level in AIS. In addition, there is no consensus regarding the exact description, relationship, and risk factors of coronal decompensation following selective fusion. In this review, we summarize the current concepts of selection of the fusion level for AIS and review the available information about postoperative coronal decompensation.

Surgical Impacts of Metastatic Nonsmall Cell Lung Cancer to the Thoracic and Lumbar Spine

Background@#Surgery for spinal metastasis is rapidly increasing in frequency with procedures ranging from laminectomy to spondylectomy combined with stabilization. This study investigated the effect of various surgical procedures for spinal metastasis of non-small cell lung cancer (NSCLC). @*Methods@#A single-center consecutive series of patients who underwent surgery for spinal metastasis of NSCLC were retrospectively reviewed. Patients' characteristics, radiographic parameters, operative data, clinical outcomes, and complications were analyzed. Surgical outcomes were assessed according to pain and performance status before and after surgery.Overall survival (OS) rate was estimated using the Kaplan-Meier method. Multivariate analysis was performed to detect factors independently associated with OS using a Cox proportional hazards model. @*Results@#Twenty-one patients were treated with laminectomy, 24 with corpectomy, 13 with spondylectomy (piecemeal or total en bloc fashion), and all procedures were combined with stabilization. Back pain and performance status improved significantly after surgical treatment among the three groups. Revision surgery due to tumor progression at the index level or spinal metastasis at another level were four patients (19.0%) in the laminectomy group, six patients (25.0%) in the corpectomy group, and one patient (7.7%) in the spondylectomy group. A Charlson comorbidity index and the number of spinal metastasis negatively affected OS (hazard ratio [HR], 19.613 and 2.244). Postoperative chemotherapy, time to metastasis, spondylectomy, and corpectomy had favorable associations with OS (HR, 0.455, 0.487, 0.619, and 0.715, respectively). @*Conclusion@#Postoperative chemotherapy was the most critical factor in OS of patients with metastatic NSCLC to the spine. An extensive surgical procedure (corpectomy/ spondylectomy) with stabilization also could be beneficial for limited patients with spinal metastasis of NSCLC.

Selection of Fusion Level for Adolescent Idiopathic Scoliosis Surgery : Selective Fusion versus Postoperative Decompensation

Adolescent idiopathic scoliosis (AIS), which is associated with an extensive range of clinical and radiological presentations, is the one of the most challenging spinal disorders. The goals of surgery are to correct the deformity in 3 dimensions and to preserve motion segments while avoiding complications. Despite the ongoing evolution of classification systems and algorithms for the surgical treatment of AIS, there has been considerable debate regarding the selection of an appropriate fusion level in AIS. In addition, there is no consensus regarding the exact description, relationship, and risk factors of coronal decompensation following selective fusion. In this review, we summarize the current concepts of selection of the fusion level for AIS and review the available information about postoperative coronal decompensation.

Comparison of Spinal Canal Expansion Following Cervical Laminoplasty Based on the Preoperative Lamina Angle : A Simulation Study

Objective@#: Expansion in the spinal canal area (SCA) after laminoplasty is one of the critical factors to relieve the preoperative symptoms. No previous study has compared the increases in SCA achieved by open-door laminoplasty (ODL) and double door laminoplasty (DDL) according to the preoperative lamina angle (LA). This study was designed to clarify the relationship between the laminoplasty opening angle (OA)/laminoplasty opening size (OS) and increases in the SCA following ODL and DDL according to the preoperative LA using a simulation model. @*Methods@#: The simulation model was constructed and validated by comparing the clinical data of 64 patients who had undergone C3–C6 laminoplasty (43 patients with ODL and 21 patients with DDL). SCA expansion was predicted with a verified simulation model at various preoperative LAs (from 28° to 32°) with different OAs (40° to 44°) and OSs (10 mm to 14 mm) recruited from patient data. @*Results@#: The constructed simulation model was validated by comparing clinical data and revealed a very high degree of correlation (r=0.935, p0.05). The difference was significant when the preoperative LA was narrower or much wider. @*Conclusion@#: Based on clinical data, a simulation model was constructed and verified that could predict increases in the SCA following ODL and DDL. When applying this model, prediction in SCA increase using the OS parameter was more practical and compatible with clinical data. Both laminoplasties achieved enough SCA, and there was no significant difference between them in the usual range.

Evaluation of Bone Marrow-derived Stem Cells and Adipose-derived Stem Cells Co-cultured on Human Nucleus Pulposus Cells: A Pilot Study / 대한신경손상학회지

Objective@#We aimed to determine whether bone marrow-derived mesenchymal stem cells (BDMSCs) effectively attenuate the degeneration of human nucleus pulposus cells (NPCs). @*Methods@#Four NPC lines were obtained from 3 subjects who underwent spinal surgery for cervical disc herniation (n=1) or lumbar disc herniation (n=2). For co-culture wells without contact, BDMSCs and adipose-derived mesenchymal stem cells (ADMSCs) were seeded on tissue culture plates and maintained for 3 days. Senescence-associated β-gal (SA-β-gal) staining was represented as a percentage of the total number of stained cells (%). The cells with intracellular lipid droplets (LDs) were represented as the percentage of the number of cells with LDs. Glycosaminoglycan (GAG) secretion was measured at 450 nm, using a commercial kit, to analyze optical density. @*Results@#The ratio of cells stained with SA-β-gal to the total number of cells reduced significantly when co-cultured with BDMSCs and ADMSCs (p<0.001 vs. p<0.001). The proportion of NPCs containing LDs was lower when co-cultured with BDMSCs than with ADMSCs (p<0.001). The optical density related to GAG secretion was lower in BDMSCs and ADMSCs co-cultured with NPCs than in the controls (p<0.001 vs. p<0.001). @*Conclusion@#SA-β-gal staining showed significant attenuation of degenerative changes in NPCs co-cultured with BDMSCs. Moreover, the unexpected increase in LDs was significantly higher in NPCs co-cultured with ADMSCs than in those co-cultured with BDMSCs. However, GAG secretion was significantly decreased in NPCs co-cultured with MSCs.

Surgical Outcomes According to Dekyphosis in Patients with Ossification of the Posterior Longitudinal Ligament in the Thoracic Spine

Objective@#: Ossification of posterior longitudinal ligament (OPLL) in the thoracic spine may cause chronic compressive myelopathy that is usually progressive, and unfavorable by conservative treatment. Although surgical intervention is often needed, the standard surgical method has not been established. Recently, it has been reported that posterior decompression with dekyphosis is effective surgical technique for favorable clinical outcome. The purpose of this study was to evaluate the surgical outcomes in patients with thoracic OPLL according to dekyphosis procedure and to identify predictive factors for the surgical results. @*Methods@#: A total of 25 patients with thoracic OPLL who underwent surgery for myelopathy from May 2004 to March 2017, were retrospectively reviewed. Patients with cervical myelopathy were excluded. We assessed the clinical outcomes according to various surgical approaches. The modified Japanese orthopedic association (JOA) scores for the thoracic spine (total, 11 points) and JOA recovery rates were used for investigating surgical outcomes. @*Results@#: Of the 25 patients, 10 patients were male and the others were female. The mean JOA score was 6.7±2.3 points preoperatively and 8.8±1.8 points postoperatively, yielding a mean recovery rate of 53.8±31.0%. The mean patients’ age at surgery was 52.4 years and mean follow-up period was 40.2 months. According to surgical approaches, seven patients underwent anterior approaches, 13 patients underwent posterior approaches, five patients underwent combined approaches. There was no significant difference of the surgical outcomes related with different surgical approaches. Age (≥55 years) and high signal intensity on preoperative magnetic resonance (MR) image in the thoracic spine were significant predictors of the lower recovery rate after surgery (p<0.05). Posterior decompression with dekyphosis procedure was related to the excellent surgical outcomes (p=0.047). Dekyphosis did not affect the complication rates. @*Conclusion@#: In this study, our result elucidated that old age (≥55 years) and presence of intramedullary high signal intensity on preoperative MR images were risk factors related to poor surgical outcomes. In the meanwhile, posterior decompression with dekyphosis affected favorable clinical outcome. Posterior approach with dekyphosis procedure can be a recommendable surgical option for favorable results.

Radiographic and Clinical Outcomes Following Pedicle Subtraction Osteotomy : Minimum 2-Year Follow-Up Data

Objective@#: The purpose of this study was to report the results of pedicle subtraction osteotomy (PSO) for fixed sagittal imbalance with a minimum 2-year follow-up. Besides, authors evaluated the effect of adjunctive multi-level posterior column osteotomy (PCO) on achievement of additional lumbar lordosis (LL) during PSO. @*Methods@#: A total of 31 consecutive patients undergoing PSO for fixed sagittal imbalance were enrolled and analyzed. Correction angle of osteotomized vertebra (PSO angle) and other radiographic parameters including pelvic incidence (PI), thoracic kyphosis, LL, and sagittal vertical axis (SVA) were evaluated. Clinical outcomes and surgical complications were also assessed. @*Results@#: The mean age was 66.0±9.3 years with a mean follow-up period of 33.2±10.5 months. The mean number of fused segments was 9.6±3.5. The mean operative time and surgical bleeding were 475.9±160.5 minutes and 1406.1±932.1 mL, respectively. The preoperative SRS-22 score was 2.3±0.7 and improved to 3.2±0.8 at the final follow-up. The mean PI was 54.5±9.5°. LL was changed from 7.0±28.9° to -50.2±13.2°. The PSO angle was 33.7±13.5° (15.6±20.1° preoperatively, -16.1±19.4° postoperatively). The difference of correction angle of LL (57.3°) was greater about 23.6° than which of PSO angle (33.7°). SVA was improved from 189.5±93.0 mm, preoperatively to 12.4±40.8 mm, postoperatively. There occurred six, eight, and 14 cases of complications at intraoperative, early (<2 weeks) postoperative, and late (≥2 weeks) postoperative period, respectively. Additional operations were needed in nine patients due to the complications. @*Conclusion@#: PSO could provide satisfactory results for patients with fixed sagittal imbalance regarding clinical and radiographic outcomes. Additional correction of LL could be achieved with conduction of adjunctive multi-level PCOs during PSO.

Trends in Incidence and Treatment of Herniated Lumbar Disc in Republic of Korea : A Nationwide Database Study

Objective@#: This study aimed to determine the incidence and analyze trends of the herniated lumbar disc (HLD) based on a national database in the Republic of Korea (ROK) from January 2008 to December 2016. @*Methods@#: This study was a retrospective analysis of data obtained from the national health-claim database provided by the National Health Insurance Service for 2008–2016 using the International Classification of Diseases. The crude incidence and age-standardized incidence of HLD were calculated, and additional analysis was conducted according to age and sex. Changes in trends in treatment methods and some treatments were analyzed using the Korean Classification of Diseases procedure codes. @*Results@#: The number of patients diagnosed with HLD was 472245 in 2008 and increased to 537577 in 2012; however, it decreased to 478697 in 2016. The pattern of crude incidence and the standardized incidence were also similar. Overall, the incidence of HLD increased annually for the 30s, 40s, 50s, and 70s until 2012 and then decreased. However, the incidence of HLD for the 80s continued to increase. The crude incidence of HLD in female patients exceeded that of male patients in their middle age (30s or 40s) and was 1.5–1.6 times higher than in male patients in their 60s. The total number of open discectomy (OD) increased from 71598 in 2008 to 93942 in 2012 and then decreased to 85846 in 2016. The rate of younger patients (the 20s, 30s, and 40s) who underwent OD was decreased, and the rate of younger patients who underwent percutaneous endoscopic lumbar discectomy was increased. However, the rate of older patients (the 70s and 80s) who underwent OD was continuously increased. @*Conclusion@#: This nationwide data on HLD from 2008 to 2016 in the ROK demonstrated that the crude incidence and the standardized incidence increased until 2012 and then decreased. The annual crude incidence was different according to age and sex. These findings may be considered when deciding future health policy, especially in countries with a similar national health insurance system (or with plans to adopt).

Surgical Outcomes and Complications Following All Posterior Approach for Spinal Deformity Associated with Neurofibromatosis Type-1

Objectives@#: The purpose of this study was to evaluate surgical outcomes and complications of spinal deformity associated with neurofibromatosis type-1 (NF-1). @*Methods@#: From 2012 to 2018, patients suffering from spinal deformity associated with NF-1 who underwent surgical correction were identified. Demographic data and radiographic measures were retrospectively reviewed. Pre- and postoperative whole spine radiograph images were used to determine both coronal and sagittal Cobb angles. All of patients underwent 3-dimentional computed tomographic scan and magnetic resonance imaging scan to confirm dystrophic features. For evaluation of clinical outcomes, we surveyed the pre- and postoperative scoliosis research society-22r (SRS-22r) score. @*Results@#: Seven patients with spinal deformity associated with NF-1 were enrolled in this study. The mean age of patients was 29.5±1.2 years old. The mean follow-up period was 2.8±1.4 years. The apex of the deformity was located in cervicothoracic (n=1), thoracic (n=4), and lumbar region (n=2). Most patients have poor bone quality and decreased bone mineral density with average T-score of -3.5±1.0. All patients underwent surgical correction via posterior approach. The pre- and postoperative mean coronal and sagittal Cobb angle was 61.6±22.6° and 34.6±38.1°, 56.8±18.5° and 40.2±9.1°, respectively. Mean correction rate of coronal and sagittal angle was 44.7% and 23.1%. Ultimate follow-up SRS-22r score (average score, 3.9±0.4) improved comparing to preoperative score (average score, 3.3±0.9). Only one patient received revision surgery due to rod fracture. No serious complication occurred, such as neurological deficit, and viscerovascular injury. @*Conclusion@#: The surgical correction of patients having spinal deformity associated with NF-1 is challenging, however the radiographic and clinical outcomes are satisfactory. The all posterior approach can be a safe and effective surgical option for patients having dystrophic curves associated with NF-1.

Clinical Efficacy of Intra-Operative Cell Salvage System in Major Spinal Deformity Surgery

OBJECTIVE: The purpose of this study was to determine the efficacy of intra-operative cell salvage system (ICS) to decrease the need for allogeneic transfusions in patients undergoing major spinal deformity surgeries. METHODS: A total of 113 consecutive patients undergoing long level posterior spinal segmental instrumented fusion (≥5 levels) for spinal deformity correction were enrolled. Data including the osteotomy status, the number of fused segments, estimated blood loss, intra-operative transfusion amount by ICS (Cell Saver®, Haemonetics©, Baltimore, MA, USA) or allogeneic blood, postoperative transfusion amount, and operative time were collected and analyzed.

Clinical Efficacy of Intra-Operative Cell Salvage System in Major Spinal Deformity Surgery

OBJECTIVE: The purpose of this study was to determine the efficacy of intra-operative cell salvage system (ICS) to decrease the need for allogeneic transfusions in patients undergoing major spinal deformity surgeries.METHODS: A total of 113 consecutive patients undergoing long level posterior spinal segmental instrumented fusion (≥5 levels) for spinal deformity correction were enrolled. Data including the osteotomy status, the number of fused segments, estimated blood loss, intra-operative transfusion amount by ICS (Cell Saver®, Haemonetics©, Baltimore, MA, USA) or allogeneic blood, postoperative transfusion amount, and operative time were collected and analyzed.RESULTS: The number of patients was 81 in ICS group and 32 in non-ICS group. There were no significant differences in demographic data and comorbidities between the groups. Autotransfusion by ICS system was performed in 53 patients out of 81 in the ICS group (65.4%) and the amount of transfused blood by ICS was 226.7 mL in ICS group. The mean intra-operative allogeneic blood transfusion requirement was significantly lower in the ICS group than non-ICS group (2.0 vs. 2.9 units, p=0.033). The regression coefficient of ICS use was -1.036.CONCLUSION: ICS use could decrease the need for intra-operative allogeneic blood transfusion. Specifically, the use of ICS may reduce about one unit amount of allogeneic transfusion in major spinal deformity surgery.

Freehand S2 Alar-Iliac Screw Placement Using K-Wire and Cannulated Screw: Technical Case Series

OBJECTIVE: Among the various sacropelvic fixation methods, S2 alar-iliac (S2AI) screw fixation has several advantages compared to conventional iliac wing screw. However, the placement of S2AI screw still remains a challenge. The purpose of this study was to describe a novel technique of free hand S2AI screw insertion using a K-wire and cannulated screw, and to evaluate the accuracy of the technique. METHODS: S2AI screw was inserted by free hand technique in sixteen consecutive patients without any fluoroscopic guidance. The gearshift was advanced to make a pilot hole passing through the sacroiliac joint and directing the anterior inferior iliac spine. A K-wire was placed through the pilot hole. After introducing a cannulated tapper along with the K-wire, a cannulated S2AI screw was installed over the K-wire. RESULTS: Thirty-three S2AI screws were placed in sixteen consecutive patients. Thirty-two screws were cannulated screws, and one screw was a conventional non-cannulated screw. Thirty out of 32 (93.8%) cannulated screws were accurately positioned, whereas two cannulated screws and one non-cannulated screw violated lateral cortex of the ilium. CONCLUSION: The technique using K-wire and cannulated screw can provide accurate placement of free hand S2AI screw.

Freehand S2 Alar-Iliac Screw Placement Using K-Wire and Cannulated Screw: Technical Case Series

OBJECTIVE: Among the various sacropelvic fixation methods, S2 alar-iliac (S2AI) screw fixation has several advantages compared to conventional iliac wing screw. However, the placement of S2AI screw still remains a challenge. The purpose of this study was to describe a novel technique of free hand S2AI screw insertion using a K-wire and cannulated screw, and to evaluate the accuracy of the technique.METHODS: S2AI screw was inserted by free hand technique in sixteen consecutive patients without any fluoroscopic guidance. The gearshift was advanced to make a pilot hole passing through the sacroiliac joint and directing the anterior inferior iliac spine. A K-wire was placed through the pilot hole. After introducing a cannulated tapper along with the K-wire, a cannulated S2AI screw was installed over the K-wire.RESULTS: Thirty-three S2AI screws were placed in sixteen consecutive patients. Thirty-two screws were cannulated screws, and one screw was a conventional non-cannulated screw. Thirty out of 32 (93.8%) cannulated screws were accurately positioned, whereas two cannulated screws and one non-cannulated screw violated lateral cortex of the ilium.CONCLUSION: The technique using K-wire and cannulated screw can provide accurate placement of free hand S2AI screw.

Clinical and Radiological Outcomes of Posterior Vertebral Column Resection for Severe Spinal Deformities

OBJECTIVE: The aim of this study was to investigate clinical and radiological outcomes of patients who underwent posterior vertebral column resection (PVCR) by a single neurosurgeon in a single institution. METHODS: Thirty-four consecutive patients with severe spinal deformities who underwent PVCR between 2010 and 2016 were enrolled. The radiographic measurements included a kyphotic angle of PVCR levels (VCR angle), sagittal vertical axis (SVA), thoracic kyphosis, lumbar lordosis (LL), and spinopelvic parameters. The data of surgical time, estimated blood loss, duration of hospital stay, complications, intraoperative neurophysiologic monitoring, and the Scoliosis Research Society (SRS)-22 questionnaire were collected using a retrospective review of medical records. RESULTS: The VCR angle, LL, and SVA values were significantly corrected after surgery. The VCR and LL angle were changed from the average of 38.4±32.1° and −22.1±39.1° to −1.7±29.4° (p < 0.001) and −46.3±23.8° (p=0.001), respectively. The SVA was significantly reduced from 103.6±88.5 mm to 22.0±46.3 mm (p=0.001). The clinical results using SRS-22 survey improved from 2.6±0.9 to 3.4±0.8 (p=0.033). There were no death and permanent neurological deficits after PVCR. However, complications occurred in 19 (55.9%) patients. Those patients experienced a total of 31 complications during- and after surgery. Sixteen reoperations were performed in twelve (35.3%) patients. The incidence of transient neurological deterioration was 5.9% (two out of 34 patients). CONCLUSION: Severe spinal deformities can be effectively corrected by PVCR. However, the PVCR technique should be utilized limitedly because surgery-related serious complications are relatively common.