Civilian Ballistic Injuries to the Atlantoaxial Spine: A Single Institution Case Series.

STUDY DESIGN: Retrospective case series. OBJECTIVE: Describe the injury characteristics of ballistic fractures involving the atlantoaxial spine. SUMMARY OF BACKGROUND DATA: Civilian gunshot wounds to the spine are an increasingly common injury in the United States. Civilian studies have focused on ballistic injuries to the entire spine as opposed to a region-specific fashion. Only a single 10-patient case series investigating ballistic fractures to the upper cervical spine (C1 and C2) exists, leaving a large gap in the understanding of this injury complex. METHODS: A retrospective chart review was performed. Extracted data included patient demographics, neurological status on presentation, fracture morphology, assessment of stability, other associated injuries, and surgical procedures performed. Proportional analysis was performed to characterize the fractures and their associated neurological injuries. RESULTS: Thirty-six patients were identified, with 86% being male with an average patient age of 30.0 ± 10.36 years (mean ± SD). Fracture morphology was characterized using proportional analysis. Initial neurological exams were either ASIA A or ASIA E, without any incomplete injuries noted. Patients who sustained a transcanal injury did not show any neurological improvement. The initial in-hospital mortality rate was 5.6%, with a 1-year mortality rate of 8.3%. There is a high incidence of associated vascular injury (66%) and mandible fracture (33%). CONCLUSIONS: Ballistic penetrating trauma to the atlantoaxial spine often results in complex injury patterns necessitating multidisciplinary care with high rates of morbidity and mortality. If neurological deficits are present initially, they are often complete. Two thirds of patients sustained an associated vascular injury, which should be screened for with CT angiography.

Duration and Magnitude of Opioid Use After Minimally Invasive Sacroiliac Joint Fusion.

STUDY DESIGN: Retrospective cohort study performed in a nationwide insurance claims database. OBJECTIVE: To evaluate the duration and magnitude of post-operative opioid prescriptions after minimally invasive surgical sacroiliac joint fusion (MIS SIJF) as compared to other common spine surgeries. SUMMARY OF BACKGROUND DATA: MIS SIJF has been reported to significantly improve quality of life and reduce pain. However, there is a paucity of reported data on post-operative opioid use in patients undergoing MIS SIJF for sacroiliac joint dysfunction. METHODS: A nationwide insurance claims database was queried to identify 4,666 patients who underwent MIS SIJF. Patients were stratified by pre-operative opioid use: Opioid naïve, sporadic use, or chronic use were respectively defined as 0,1, or≥2 opioid prescriptions filled within 6 months prior to surgery. Duration of opioid use was defined by the time between MIS SIJF and last opioid prescription filled while magnitude of opioid use was determined by milligram morphine equivalents filled by 30 days post-operation. This opioid use data was compared to that of other common spine surgeries. RESULTS: Patients undergoing MIS SIJF continued to fill opioid prescriptions 1-year post-operatively at significantly higher proportions than those undergoing other common spine procedures assessed by prior literature within each of the pre-operative opioid use cohorts (chronic: 73% vs. 49-62%; P <0.0001, sporadic: 39% vs. 23-28%; P <0.0001, opioid naïve: 22% vs. 15-18%; P <0.0001). Chronic users filled the highest opiate dosages during the 30-day post-operative period, filling on average 64.75 MME/d compared to 19.75 MME/d and 24.25 MME/d by the opioid naïve and sporadic users, respectively. CONCLUSION: After MIS SIJF, opioid naïve patients use fewer opioids and for a shorter period of time compared to patients with sporadic or chronic pre-operative opioid use. MIS SIJF may result in less effective pain reduction when compared to other common spine surgeries evaluated via identical methodology.

Rates of Future Lumbar Fusion in Patients with Cauda Equina Syndrome Treated With Decompression.

INTRODUCTION: The long-term risk of conversion to lumbar fusion is ill-defined for patients with cauda equina syndrome (CES) treated with decompression. This study aimed to identify the rates of fusion in patients with CES and compare those rates with a matched lumbar spinal stenosis (LSS) group. METHODS: Patients with CES who underwent decompression were identified in a national database and matched to control patients with LSS. The rates of conversion to fusion were identified and compared. Multivariate logistic regression analysis identified independently associated risk factors. A subanalysis was conducted after stratifying by timing between CES diagnosis and decompression. RESULTS: The rate of lumbar fusion in the CES cohort was 3.6% after 1 year, 6.7% after 3 years, and 7.8% after 5 years, significantly higher than the LSS control group at all time points (1 year: 1.6%, P = 0.001; 3 years: 3.0%, P < 0.001; 5 years: 3.8%, P < 0.001). CES was independently associated with increased risk of conversion to fusion (odds ratio: 2.13; 95% confidence interval: 1.56 to 2.97; P < 0.001). Surgical timing was not associated with risk of conversion to fusion. CONCLUSIONS: After 5 years, 7.8% of patients with CES underwent fusion, a markedly higher rate compared with patients with LSS. Counseling patients with CES on this increased risk of future surgery is important for patient education and satisfaction.

SATB2: A versatile transcriptional regulator of craniofacial and skeleton development, neurogenesis and tumorigenesis, and its applications in regenerative medicine.

SATB2 (special AT-rich sequence-binding protein 2) is a member of the special AT-rich binding protein family. As a transcription regulator, SATB2 mainly integrates higher-order chromatin organization. SATB2 expression appears to be tissue- and stage-specific, and is governed by several cellular signaling molecules and mediators. Expressed in branchial arches and osteoblast-lineage cells, SATB2 plays a significant role in craniofacial pattern and skeleton development. In addition to regulating osteogenic differentiation, SATB2 also displays versatile functions in neural development and cancer progression. As an osteoinductive factor, SATB2 holds great promise in improving bone regeneration toward bone defect repair. In this review, we have summarized our current understanding of the physiological and pathological functions of SATB2 in craniofacial and skeleton development, neurogenesis, tumorigenesis and regenerative medicine.

Migration of an Anterior Cervical Discectomy and Fusion Screw into the Constrictor Muscle of the Hypopharynx: A Case Report.

CASE: A 53-year-old man developed dysphagia 4 years after anterior cervical discectomy and fusion (ACDF), and radiographs revealed a dislodged screw anterior to the ACDF plate. Intraoperatively, the screw was found to be completely embedded within the pharyngeal constrictor muscle fibers and was removed with assistance from otolaryngology without injury to the pharyngeal mucosa. CONCLUSION: Implant migration after ACDF can variably damage tracheoesophageal and retropharyngeal structures, and a multidisciplinary approach involving otolaryngology or thoracic surgery may be required to diagnose and treat these complications.

Applications of Biocompatible Scaffold Materials in Stem Cell-Based Cartilage Tissue Engineering.

Cartilage, especially articular cartilage, is a unique connective tissue consisting of chondrocytes and cartilage matrix that covers the surface of joints. It plays a critical role in maintaining joint durability and mobility by providing nearly frictionless articulation for mechanical load transmission between joints. Damage to the articular cartilage frequently results from sport-related injuries, systemic diseases, degeneration, trauma, or tumors. Failure to treat impaired cartilage may lead to osteoarthritis, affecting more than 25% of the adult population globally. Articular cartilage has a very low intrinsic self-repair capacity due to the limited proliferative ability of adult chondrocytes, lack of vascularization and innervation, slow matrix turnover, and low supply of progenitor cells. Furthermore, articular chondrocytes are encapsulated in low-nutrient, low-oxygen environment. While cartilage restoration techniques such as osteochondral transplantation, autologous chondrocyte implantation (ACI), and microfracture have been used to repair certain cartilage defects, the clinical outcomes are often mixed and undesirable. Cartilage tissue engineering (CTE) may hold promise to facilitate cartilage repair. Ideally, the prerequisites for successful CTE should include the use of effective chondrogenic factors, an ample supply of chondrogenic progenitors, and the employment of cell-friendly, biocompatible scaffold materials. Significant progress has been made on the above three fronts in past decade, which has been further facilitated by the advent of 3D bio-printing. In this review, we briefly discuss potential sources of chondrogenic progenitors. We then primarily focus on currently available chondrocyte-friendly scaffold materials, along with 3D bioprinting techniques, for their potential roles in effective CTE. It is hoped that this review will serve as a primer to bring cartilage biologists, synthetic chemists, biomechanical engineers, and 3D-bioprinting technologists together to expedite CTE process for eventual clinical applications.

Notch signaling: Its essential roles in bone and craniofacial development.

Notch is a cell-cell signaling pathway that is involved in a host of activities including development, oncogenesis, skeletal homeostasis, and much more. More specifically, recent research has demonstrated the importance of Notch signaling in osteogenic differentiation, bone healing, and in the development of the skeleton. The craniofacial skeleton is complex and understanding its development has remained an important focus in biology. In this review we briefly summarize what recent research has revealed about Notch signaling and the current understanding of how the skeleton, skull, and face develop. We then discuss the crucial role that Notch plays in both craniofacial development and the skeletal system, and what importance it may play in the future.

BMP9-initiated osteogenic/odontogenic differentiation of mouse tooth germ mesenchymal cells (TGMCS) requires Wnt/ß-catenin signalling activity.

Teeth arise from the tooth germ through sequential and reciprocal interactions between immature epithelium and mesenchyme during development. However, the detailed mechanism underlying tooth development from tooth germ mesenchymal cells (TGMCs) remains to be fully understood. Here, we investigate the role of Wnt/ß-catenin signalling in BMP9-induced osteogenic/odontogenic differentiation of TGMCs. We first established the reversibly immortalized TGMCs (iTGMCs) derived from young mouse mandibular molar tooth germs using a retroviral vector expressing SV40 T antigen flanked with the FRT sites. We demonstrated that BMP9 effectively induced expression of osteogenic markers alkaline phosphatase, collagen A1 and osteocalcin in iTGMCs, as well as in vitro matrix mineralization, which could be remarkably blunted by knocking down ß-catenin expression. In vivo implantation assay revealed that while BMP9-stimulated iTGMCs induced robust formation of ectopic bone, knocking down ß-catenin expression in iTGMCs remarkably diminished BMP9-initiated osteogenic/odontogenic differentiation potential of these cells. Taken together, these discoveries strongly demonstrate that reversibly immortalized iTGMCs retained osteogenic/odontogenic ability upon BMP9 stimulation, but this process required the participation of canonical Wnt signalling both in vitro and in vivo. Therefore, BMP9 has a potential to be applied as an efficacious bio-factor in osteo/odontogenic regeneration and tooth engineering. Furthermore, the iTGMCs may serve as an important resource for translational studies in tooth tissue engineering.

Long-term rates of bladder dysfunction after decompression in patients with cauda equina syndrome.

BACKGROUND CONTEXT: Cauda equina syndrome (CES) occurs due to compression of the lumbar and sacral nerve roots and is considered a surgical emergency. Although the condition is relatively rare, the associated morbidity can be devastating to patients. While substantial research has been conducted on the timing of treatment, the literature regarding long-term rates of bladder dysfunction in CES patients is scarce. PURPOSE: The aim of this study was to identify long-term rates of bladder dysfunction in CES patients and to compare those rates to non-CES patients who underwent similar spinal decompression. STUDY DESIGN/SETTING: Retrospective database study. PATIENT SAMPLE: The CES cohort was comprised of 2,362 patients who underwent decompression surgery following CES diagnosis with a 5-year follow-up. These patients were matched to 9,448 non-CES control patients who underwent spinal decompression without a diagnosis of CES. OUTCOME MEASURES: Diagnosis of bladder dysfunction, surgical procedure to address bladder dysfunction METHODS: Using the national insurance claims database, PearlDiver, CES patients who underwent decompression surgery were identified and 1:4 matched to non-CES patients who underwent similar spinal decompression surgery. The 1-year, 3-year, and 5-year rates of progression to a bladder dysfunction diagnosis and surgical intervention to manage bladder dysfunction were recorded. The CES and non-CES groups were compared with univariate testing, and an analysis of risk factors for bladder dysfunction was performed with multivariate logistic regression analysis. RESULTS: A total of 2,362 CES patients who underwent decompression surgery were identified and matched to 9,448 non-CES control patients. After 5 years, CES patients had a 10%-12% increased absolute risk of continued bladder dysfunction and a 0.7%-0.9% increased absolute risk of undergoing a surgical procedure for bladder dysfunction, as compared to matched non-CES patients. Multivariate analysis controlling for age, sex, obesity, tobacco use, and diabetes, identified CES as independently associated with increased 5-year risk for bladder dysfunction diagnosis (odds ratio [OR]: 1.72; 95% confidence interaval [CI] 1.56-1.89; p<.001) and procedure (OR: 1.40; 95% CI 1.07-1.81; p=.012). CONCLUSIONS: Understanding the long-term risk for bladder dysfunction in CES patients is important for the future care and counseling of patients. Compared to non-CES patients who underwent similar spinal decompression, CES patients were observed to have a significantly higher long-term likelihood for both bladder dysfunction diagnosis and urologic surgical procedure.

The Influence of Selective Serotonin Reuptake Inhibitors on Lumbar Arthrodesis.

STUDY DESIGN: Retrospective analysis using the PearlDiver national insurance claims database. OBJECTIVE: To investigate the relationship between chronic preoperative selective serotonin reuptake inhibitor (SSRI) prescriptions and nonunion following spine fusion surgery. SUMMARY OF BACKGROUND DATA: Contemporary literature has linked SSRIs to decreased bone mineral density and increased rates of future bone fracture. Furthermore, a recent murine model has suggested a potential role in the quality of fracture healing itself. METHODS: All single-level lumbar fusion patients were identified. The rate of nonunion diagnosis between 6 and 24 months following surgery was assessed. A stratified analysis of chronic SSRI use and a number of comorbidities was conducted, followed by a multiple logistic regression analysis of nonunion accounting for qualifying risk factors. Finally, subanalyses of individual procedure codes were carried out. RESULTS: In total, 7905 single-level lumbar fusion patients were included. In the multivariate analysis, chronic SSRI [odds ratio (OR): 1.558, P=0.004] and tobacco use (OR: 1.500, P=0.011) were identified as independent risk factors for nonunion, whereas patient age over 60 years (OR: 0.468, P<0.001) was observed to be negatively associated with nonunion. In the individual procedure subanalyses, SSRIs were significantly associated with nonunion in 2 of 3 univariate analyses and observed to be an independent risk factor for nonunion in 2 of the 3 procedure populations. CONCLUSIONS: These data suggest that patients treated concomitantly for mental health disorders with SSRIs before arthrodesis may be at an increased risk of postoperative nonunion. Closer follow-up may be indicated in this patient population.

Rod fractures and nonunions after long fusion to the sacrum for primary presentation adult spinal deformity: a comparison with and without interbody fusion in the distal lumbar spine.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To investigate the prevalence and incidence rate of rod fractures (RF) in patients undergoing surgery for correction of adult spinal deformity (ASD) with or without the use of interbody fusions in the caudal levels of the fusion construct. BACKGROUND: Data: Pseudarthrosis and rod fracture after long spinal fusion to the sacrum for correction of ASD remain a concern. METHODS: We reviewed clinical records of patients who underwent surgery for correction of ASD between 2004 and 2014. All cases were primary (no prior spine fusion) surgeries with long fusion to the sacrum and bilateral spinopelvic fixation. Patients were dichotomized into one of two groups based on whether an interbody fusion was performed at the caudal levels of the fusion construct. The primary outcome of interest was the prevalence and incidence rate of RFs. RESULTS: A total of 230 patients underwent a long segment fusion for correction of ASD with mean follow-up of 55 months. 117 patients had an interbody fusion (IF) while 113 patients did not (NIF). At last follow-up, there was no significant difference in the prevalence of RFs between the cohort of patients IF vs NIF (IF cohort: n = 20, 17.9% vs NIF cohort: n = 15, 14.2%, p = 0.49). However, the incidence rate for bilateral rod fractures was 1.6%/year for IF group vs 1.0%/year for NIF group (p = 0.02). Location of RF was different between the two groups; RF (unilateral and bilateral) above L4 was the most common location in the IF group (n = 17/20; 85%) compared to L4-S1 in the NIF group (n = 11/15; 73%) (p = 0.02). CONCLUSION: Interbody fusion does not fully protect against rod failure in the lumbar spine in ASD patients with long posterior spinal fusion and may encourage failure at L2-L4, the levels above the interbody fusion. LEVEL OF EVIDENCE: III.

Stem Cell-Friendly Scaffold Biomaterials: Applications for Bone Tissue Engineering and Regenerative Medicine.

Bone is a dynamic organ with high regenerative potential and provides essential biological functions in the body, such as providing body mobility and protection of internal organs, regulating hematopoietic cell homeostasis, and serving as important mineral reservoir. Bone defects, which can be caused by trauma, cancer and bone disorders, pose formidable public health burdens. Even though autologous bone grafts, allografts, or xenografts have been used clinically, repairing large bone defects remains as a significant clinical challenge. Bone tissue engineering (BTE) emerged as a promising solution to overcome the limitations of autografts and allografts. Ideal bone tissue engineering is to induce bone regeneration through the synergistic integration of biomaterial scaffolds, bone progenitor cells, and bone-forming factors. Successful stem cell-based BTE requires a combination of abundant mesenchymal progenitors with osteogenic potential, suitable biofactors to drive osteogenic differentiation, and cell-friendly scaffold biomaterials. Thus, the crux of BTE lies within the use of cell-friendly biomaterials as scaffolds to overcome extensive bone defects. In this review, we focus on the biocompatibility and cell-friendly features of commonly used scaffold materials, including inorganic compound-based ceramics, natural polymers, synthetic polymers, decellularized extracellular matrix, and in many cases, composite scaffolds using the above existing biomaterials. It is conceivable that combinations of bioactive materials, progenitor cells, growth factors, functionalization techniques, and biomimetic scaffold designs, along with 3D bioprinting technology, will unleash a new era of complex BTE scaffolds tailored to patient-specific applications.

Comprehensive classification system for multirod constructs across three-column osteotomies: a reliability study.

OBJECTIVE: In this study, the authors' goal was to determine the intra- and interobserver reliability of a new classification system that allows the description of all possible constructs used across three-column osteotomies (3COs) in terms of rod configuration and density. METHODS: Thirty-five patients with multirod constructs (MRCs) across a 3CO were classified by two spinal surgery fellows according to the new system, and then were reclassified 2 weeks later. Constructs were classified as follows: the number of rods across the osteotomy site followed by a letter corresponding to the type of rod configuration: "M" is for a main rod configuration, defined as a single rod spanning the osteotomy. "L" is for linked rod configurations, defined as 2 rods directly connected to each other at the osteotomy site. "S" is for satellite rod configurations, which were defined as a short rod independent of the main rod with anchors above and below the 3CO. "A" is for accessory rods, defined as an additional rod across the 3CO attached to main rods but not attached to any anchors across the osteotomy site. "I" is for intercalary rod configurations, defined as a rod connecting 2 separate constructs across the 3CO, without the intercalary rod itself attached to any anchors across the osteotomy site. The intra- and interobserver reliability of this classification system was determined. RESULTS: A sample estimation for validation assuming two readers and 35 subjects results in a two-sided 95% confidence interval with a width of 0.19 and a kappa value of 0.8 (SD 0.3). The Fleiss kappa coefficient (κ) was used to calculate the degree of agreement between interrater and intraobserver reliability. The interrater kappa coefficient was 0.3, and the intrarater kappa coefficient was 0.63 (good reliability). This scenario represents a high degree of agreement despite a low kappa coefficient. Correct observations by both observers were 34 of 35 and 33 of 35 at both time points. Misclassification was related to difficulty in determining connectors versus anchors. CONCLUSIONS: MRCs across 3COs have variable rod configurations. Currently, no classification system or agreement on nomenclature exists to define the configuration of rods across 3COs. The authors present a new, comprehensive MRC classification system with good inter- and intraobserver reliability and a high degree of agreement that allows for a standardized description of MRCs across 3COs.

Preoperative patient expectations and pain improvement after adult spinal deformity surgery.

OBJECTIVE: Patients' expectations for pain relief are associated with patient-reported outcomes after treatment, although this has not been examined in patients with adult spinal deformity (ASD). The aim of this study was to identify associations between patients' preoperative expectations for pain relief after ASD surgery and patient-reported pain at the 2-year follow-up. METHODS: The authors analyzed surgically treated ASD patients at a single institution who completed a survey question about expectations for back pain relief. Five ordinal answer choices to "I expect my back pain to improve" were used to categorize patients as having low or high expectations. Back pain was measured using the 10-point numeric rating scale (NRS) and Scoliosis Research Society-22r (SRS-22r) patient survey. Preoperative and postoperative pain were compared using analysis of covariance. RESULTS: Of 140 ASD patients eligible for 2-year follow-up, 105 patients (77 women) had pre- and postoperative data on patient expectations, 85 of whom had high expectations. The mean patient age was 59 ± 12 years, and 46 patients (44%) had undergone previous spine surgery. The high-expectations and low-expectations groups had similar baseline demographic and clinical characteristics (p > 0.05), except for lower SRS-22r mental health scores in those with low expectations. After controlling for baseline characteristics and mental health, the mean postoperative NRS score was significantly better (lower) in the high-expectations group (3.5 ± 3.5) than in the low-expectations group (5.4 ± 3.7) (p = 0.049). The mean postoperative SRS-22r pain score was significantly better (higher) in the high-expectations group (3.3 ± 1.1) than in the low-expectations group (2.6 ± 0.94) (p = 0.019). CONCLUSIONS: Despite similar baseline characteristics, patients with high preoperative expectations for back pain relief reported less pain 2 years after ASD surgery than patients with low preoperative expectations.

Leptin Potentiates BMP9-Induced Osteogenic Differentiation of Mesenchymal Stem Cells Through the Activation of JAK/STAT Signaling.

Mesenchymal stem cells (MSCs) are multipotent progenitors that have the ability to differentiate into multiple lineages, including bone, cartilage, and fat. We previously demonstrated that the least known bone morphogenetic protein (BMP)9 (also known as growth differentiation factor 2) is one of the potent osteogenic factors that can induce both osteogenic and adipogenic differentiation of MSCs. Nonetheless, the molecular mechanism underlying BMP9 action remains to be fully understood. Leptin is an adipocyte-derived hormone in direct proportion to the amount of body fat, and exerts pleiotropic functions, such as regulating energy metabolism, bone mass, and mineral density. In this study, we investigate the potential effect of leptin signaling on BMP9-induced osteogenic differentiation of MSCs. We found that exogenous leptin potentiated BMP9-induced osteogenic differentiation of MSCs both in vitro and in vivo, while inhibiting BMP9-induced adipogenic differentiation. BMP9 was shown to induce the expression of leptin and leptin receptor in MSCs, while exogenous leptin upregulated BMP9 expression in less differentiated MSCs. Mechanistically, we demonstrated that a blockade of JAK signaling effectively blunted leptin-potentiated osteogenic differentiation induced by BMP9. Taken together, our results strongly suggest that leptin may potentiate BMP9-induced osteogenesis by cross-regulating BMP9 signaling through the JAK/STAT signaling pathway in MSCs. Thus, it is conceivable that a combined use of BMP9 and leptin may be explored as a novel approach to enhancing efficacious bone regeneration and fracture healing.

The Times, They Are A-Changing: Women Entering Academic Orthopedics Today Are Choosing Nonpediatric Fellowships at a Growing Rate.

OBJECTIVE: Pediatrics and hand surgery have historically been the orthopaedic subspecialties with the highest female representations. We sought to identify the gender distribution of orthopedic surgical faculty by subspecialty, geography, and educational background. We hypothesized that the proportion of women entering pediatric orthopaedics has decreased since 1980. DESIGN: The Accreditation Council for Graduate Medical Education was used to generate a list of U.S. orthopedic residencies. Program websites were used to collect data regarding each faculty member's gender, residencies, fellowships, and graduation year. t tests were used to compare quantitative data and Fisher's exact tests to compare categorical data. Significance was defined as p < 0.05. SETTING: Publicly available data from official websites of U.S. orthopedic residencies. PARTICIPANTS: Of 153 residencies, 142 (93%) had accessible faculty lists. RESULTS: Of 3596 orthopedic surgeons, 7.9% were women. Among fellowship-trained faculty, 22% of pediatric orthopedists were women compared with 7.6% of faculty in other orthopedic subspecialties (p < 0.00001). There was a significantly higher percentage of female faculty in the West (13%) than in any other U.S. census region (p < 0.001 vs. Midwest, vs. South, and vs. Northeast). A strong correlation with time was found in number of women completing fellowships other than hand or pediatrics from 1980 to 2014 (R2 = 0.95); a strong inverse correlation with time was found for pediatrics as a percentage of fellowships completed by women during the same period (R2 = 0.94). CONCLUSIONS: Although pediatrics remains the most popular fellowship for female orthopedists, women who enter academic orthopedics are increasingly choosing nonpediatric subspecialties.

Minimally Invasive Fixation for Spinopelvic Dissociation: Percutaneous Triangular Osteosynthesis with S2 Alar-Iliac and Iliosacral Screws: A Case Report.

CASE: Traumatic U- and H-type sacral fractures are often unstable, causing spinopelvic dissociation. We describe a minimally invasive approach that allows percutaneous spinopelvic fixation of unstable H-type sacral fractures using a triangular osteosynthesis construct with S2 alar-iliac screws. We present the case of a patient with traumatic lumbopelvic dissociation who underwent percutaneous S2 alar-iliac and iliosacral screw fixation. CONCLUSIONS: Combined percutaneous S2 alar-iliac and iliosacral screw fixation is a safe option for spinopelvic fixation and avoids the soft-tissue compromise of open approaches. The triangular osteosynthesis construct provides adequate pelvic anchor points to allow immediate weight-bearing.

Difficulties in Treating Postirradiation Kyphosis in Adults: A Series of Five Cases.

STUDY DESIGN: Clinical case series. OBJECTIVE: To assess objective outcomes of surgical correction of post-external beam radiation therapy (ERBT) kyphosis in a series of five adults. SUMMARY OF BACKGROUND DATA: EBRT is a well-established treatment for many cancers in children and adults. One complication associated with EBRT is postirradiation spine deformity. Scoliosis is the most common deformity, but kyphosis also occurs frequently. Differences in deformity patterns are likely related to the location and intensity of radiation. To our knowledge, no studies have addressed treatment of these deformities in adults, and the most recent case series (of children) was published in 2005. METHODS: We present a series of five adults who underwent surgery for postirradiation kyphosis, with a mean follow-up of 3.8 years (range, 2.5-6.2 years). RESULTS: Surgery improved the kyphotic deformity in all patients. Overall mean kyphotic deformity correction was 56° and was larger for cervical/cervicothoracic deformities (mean, 76°) than for lumbar deformities (mean, 42°) at midterm follow-up. Patients reported significant improvements in pain and self-image. Consistent with prior case series of children, we observed a high rate of complications (mean, 1.4 complications per patient) in adults. Three patients each underwent an unplanned surgical procedure because of a complication. CONCLUSION: The surgical treatment of postirradiation kyphotic spinal deformity is challenging, with common postoperative complications such as infection, instrumentation failure, and pseudarthrosis. However, with modern surgical techniques and spinal instrumentation, excellent deformity correction can be achieved and maintained. We recommend performing a two-stage procedure for cervicothoracic deformity, with anterior release followed by posterior fusion and instrumentation. In thoracolumbar deformities, correction can be achieved through single-stage posterior fusion. Rigid spinopelvic fixation with sacral-alar-iliac screws and second-stage anterior lumbar interbody fusion at L5-S1 is recommended to reduce nonunion risk. Cement augmentation of proximal and distal anchors can help prevent junctional failure. LEVEL OF EVIDENCE: Level IV.

Comparison of rod fracture rates in long spinal deformity constructs after transforaminal versus anterior lumbar interbody fusions: a single-institution analysis.

OBJECTIVE: Pseudarthrosis is a common complication of long-segment fusions after surgery for correction of adult spinal deformity (ASD). Interbody fusions are frequently used at the caudal levels of long-segment spinal deformity constructs as adjuncts for anterior column support. There is a paucity of literature comparing rod fracture rates (proxy for pseudarthrosis) in patients undergoing transforaminal lumbar interbody fusion (TLIF) versus anterior lumbar interbody fusion (ALIF) at the caudal levels of the long spinal deformity construct. In this study the authors sought to compare rod fracture rates in patients undergoing surgery for correction of ASD with TLIF versus ALIF at the caudal levels of long spinal deformity constructs. METHODS: We reviewed clinical records of patients who underwent surgery for correction of ASD between 2008 and 2014 at a single institution. Data including demographics, comorbidities, and indications for surgery, as well as postoperative variables, were collected for each patient. All patients had a minimum 2-year follow-up. Patients were dichotomized into two groups for comparison on the basis of undergoing a TLIF versus an ALIF procedure at the caudal levels of long spinal deformity constructs. The primary outcome of interest was the rate of rod fractures. RESULTS: A total of 198 patients (TLIF 133 patients; ALIF 65 patients) underwent a long-segment fusion to the sacrum with iliac fixation. The mean ± standard deviation follow-up period was 62.23 ± 29.26 months. Baseline demographic variables were similar in both patient groups. There were no significant differences between groups in the severity of the baseline sagittal plane deformity (i.e., baseline lumbar-pelvic parameters) or the final deformity correction achieved. Mean total recombinant human bone morphogenetic protein 2 (rhBMP-2) dose for L1-sacrum fusion was significantly higher in the ALIF (100 mg) than in the TLIF (62 mg) group. The overall rod failure rate (cases with rod fracture/total cases) within this case series was 19.19% (38/198); 10.60% (21/198) were unilateral rod fractures and 8.58% (17/198) were bilateral rod fractures. At last clinical follow-up, there were no statistically significant differences in bilateral rod fracture rates between the group of patients who had a TLIF procedure and the group who had an ALIF procedure at the caudal levels of the long spinal deformity constructs (TLIF 10.52% vs ALIF 4.61%, p = 0.11). However, the incidence rate (cases per patient follow-up years) for bilateral rod fractures was significantly higher in the TLIF than in the ALIF cohort (TLIF 2.20% vs ALIF 0.70%, p < 0.0001). The reoperation rate for rod fractures was similar between the patient groups (p = 0.40). CONCLUSIONS: Although both ALIF and TLIF procedures at the caudal levels of long spinal deformity constructs achieved similar and satisfactory deformity correction, ALIFs were associated with a lower rod fracture incidence rate. There were no differences between groups in the prevalence of rod fracture or revision surgery, however, and both groups had low bilateral rod fracture prevalence and incidence rates. One technique is not clearly superior to the other.

The learning curve for performing three-column osteotomies in adult spinal deformity patients: one surgeon's experience with 197 cases.

BACKGROUND CONTEXT: Three-column osteotomy (3CO) is used to correct rigid adult spinal deformity. It presents risk of complications because it involves extensive osseous resection and spinal destabilization. PURPOSE: Our purpose was to characterize the learning curve for performing 3CO in adult spinal deformity patients. DESIGN: Retrospective review. PATIENT SAMPLE: A surgical registry at a tertiary care center was used to identify 238 cases of 3CO for correction of adult spinal deformity by 1 surgeon between 2005 and 2014. Patients with at least 1 year of clinical and radiographic follow-up were included (n=197; mean duration of follow-up, 43 months; range, 12-121). OUTCOME MEASURES: We quantified associations between surgeon experience and (1) estimated blood loss per vertebral level fused (EBL/VLF), (2) incidence of new neurologic deficits, (3) incidence of reoperation for instrumentation failure, (4) operative time in minutes, and (5) magnitude of correction at the level of the osteotomy. METHODS: The learning curve for binary outcomes was demonstrated using a LOWESS smoother plot of the probability of occurrence. Change in risk was calculated using a generalized linear model with link identity and binomial family. The learning curve for continuous variables was demonstrated using a scatter plot and a line of best fit based on linear regression analysis. Alpha=0.05. RESULTS: EBL/VLF decreased by a mean of 19.7 mL (95% confidence interval [CI]: 11.3-28.1) with each 10 cases (decrease of 388 mL/level fused by the end of the study period). The risk of a neurologic deficit declined by 7.98% (95% CI: 7.98%, 7.99%) with every 100 cases. The risk of reoperation declined by 1.99% (95% CI: 0.83%, 3.17%) with every 10 cases until the 100th case. After that point, there was no significant change in the probability of reoperation (p>.05). The magnitude of correction and operative time did not change with increasing surgeon experience (p>.05). CONCLUSION: Incidence of reoperation for instrumentation failure, incidence of new neurologic deficits, and estimated blood loss improved with increasing surgeon experience at performing 3CO. Most outcomes, except the risk of reoperation, improved through the last case.