Cardiopulmonary Cement Embolism Following Cement-Augmented Pedicle Screw Fixation: A Narrative Review.

Fixation using cement-augmented pedicle screws (CAPS) is being increasingly performed. However, CAPS-associated cement leakage is a critical problem that can lead to cardiopulmonary cement embolism (CPCE). This narrative review aimed to explore the incidence of and risk factors and treatment strategies for CPCE and cement leakage-related complications after CAPS fixation. Data were extracted from each article, including characteristics of CPCE after CAPS fixation (incidence, location, diagnostic method and criteria, treatment, and outcome and prognosis). Overall, 28 case series and 14 case reports that met the inclusion criteria were included. Of the 1974 cases included in the review, CPCE was noted in 123, symptomatic CPCE in 35, and death in six, respectively. The frequencies of PCE and symptomatic PCE after CAPS fixation were 6% (range: 0-28.6%) and 1.3% (range: 0-26%), respectively. The range of frequencies of PCE and symptomatic PCE after CAPS fixation may have been wide because the definition of CPCE and data collection methods differed among the reports analyzed. Since PCE due to large cement emboli may be primarily related to the surgical technique, improved technique, such as minimizing the number of CAPSs by injecting low-volume high-viscosity cement at low velocity and pressure, and careful observation of cement leakage during CAPS insertion may reduce PCE associated with cement leakage. Spinal surgeons should pay more attention to the occurrence of CPCE during and after CAPS insertion, which can cause serious complications in some patients.

Leukemia/lymphoma-related factor (LRF) or osteoclast zinc finger protein (OCZF) overexpression promotes osteoclast survival by increasing Bcl-xl mRNA: A novel regulatory mechanism mediated by the RNA binding protein SAM68.

RANKL induces NFATc1, a key transcriptional factor to induce osteoclast-specific genes such as cathepsin K, whereas transcriptional control of osteoclast survival is not fully understood. Leukemia/lymphoma-related factor (LRF) in mouse and osteoclast zinc finger protein (OCZF) in rat are zinc finger and BTB domain-containing protein (zBTB) family of transcriptional regulators, and are critical regulators of hematopoiesis. We have previously shown that differentiation and survival were enhanced in osteoclasts from OCZF-Transgenic (Tg) mice. In the present study, we show a possible mechanism of osteoclast survival regulated by LRF/OCZF and the role of OCZF overexpression in pathological bone loss. In the in vitro cultures, LRF was highly colocalized with NFATc1 in cells of early stage in osteoclastogenesis, but only LRF expression persisted after differentiation into mature osteoclasts. LRF expression was further enhanced in resorbing osteoclasts formed on dentin slices. Osteoclast survival inhibitor such as alendronate, a bisphosphonate reduced LRF expression. Micro CT evaluation revealed that femurs of OCZF-Tg mice showed significantly lower bone volume compared to that of WT mice. Furthermore, OCZF overexpression markedly promoted bone loss in ovariectomy-induced osteolytic mouse model. The expression of anti-apoptotic Bcl-xl mRNA, which is formed by alternative splicing, was enhanced in the cultures in which osteoclasts are formed from OCZF-Tg mice. In contrast, the expression of pro-apoptotic Bcl-xs mRNA was lost in the culture derived from OCZF-Tg mice. We found that the expression levels of RNA binding splicing regulator, Src substrate associated in mitosis of 68 kDa (Sam68) protein were markedly decreased in OCZF-Tg mice-derived osteoclasts. In addition, shRNA-mediated knockdown of Sam68 expression increased the expression of Bcl-xl mRNA, suggesting that SAM68 regulates the expression of Bcl-xl. These results indicate that OCZF overexpression reduces protein levels of Sam68, thereby promotes osteoclast survival, and suggest that LRF/OCZF is a promising target for regulating pathological bone loss.

Development of Silver-Containing Hydroxyapatite-Coated Antimicrobial Implants for Orthopaedic and Spinal Surgery.

The prevention of surgical site infections is directly related to the minimization of surgical invasiveness, and is in line with the concept of minimally invasive spine therapy (MIST). In recent years, the incidence of postoperative infections has been increasing due to the increased use of spinal implant surgery in patients at high risk of infection, including the elderly and easily infected hosts, the limitations of poor bone marrow transfer of antibiotics, and the potential for contamination of surgical gloves and instruments. Thus, the development of antimicrobial implants in orthopedic and spinal surgery is becoming more and more popular, and implants with proven antimicrobial, safety, and osteoconductive properties (i.e., silver, iodine, antibiotics) in vitro, in vivo, and in clinical trials have become available for clinical use. We have developed silver-containing hydroxyapatite (Ag-HA)-coated implants to prevent post-operative infection, and increase bone fusion capacity, and have successfully commercialized antibacterial implants for hip prostheses and spinal interbody cages. This narrative review overviews the present status of available surface coating technologies and materials; describes how the antimicrobial, safety, and biocompatibility (osteoconductivity) of Ag-HA-coated implants have been demonstrated for commercialization; and reviews the clinical use of antimicrobial implants in orthopedic and spinal surgery, including Ag-HA-coated implants that we have developed.

Adjacent vertebral fractures in the lumbar and thoracic spine after balloon kyphoplasty: A finite element analysis.

The purpose of the present study was to mechanically verify after vertebral augmentation (AVA) scores using a finite element method (FEM) with accurate material constants of balloon kyphoplasty (BKP) cement. Representative cases with AVA scores of 1 (case 1), 3 (case 2), and 5 (case 3) among patients with vertebral body fractures who underwent BKP were analyzed. A FEM model consisting of 5 vertebral bodies was created, including the injured vertebral body in each case. The amount of displacement for each load (up to 4000 N) between the upper and lower vertebral bodies of each model was measured. Young modulus of the BKP cement was calculated from actual measurements using the EZ-Test EZ-S (Shimadzu Corporation, Kyoto, Japan). In all cases, the number of shell elements (209,296-299,876), solid elements (1913,029-2417,671), and nodes (387,848-487,756) were similar, indicating that FEM modeling was comparable among the cases. Young modulus of BKP cement, calculated using EZ-Test EZ-S, was 572 MPa. Fractures were detected by compressive forces of 3300 N (upper) and 3300 N (lower), 3000 N (upper) and 3100 N (lower), and 1200 N (upper) and 1200 N (lower) in cases 1, 2, and 3, respectively. The AVA scoring system was mechanically verified using the accurate material constants of BKP cement. A multicenter survey and external validation are therefore required for the clinical implementation of the AVA score.

Biomechanical Characteristics of Kissing Spine During Extension Using a Human Cadaveric Lumbar Spinal Model.

Introduction: Although kissing spine syndrome in the lumbar spinal region is a relatively common condition in older adults, no study examining its biomechanical characteristics has been reported. We hypothesized that kissing of the spinous processes during extension causes an increase in the flexural rigidity of the spine and significantly limits the deformation behavior of extension, which in turn might cause lower back pain. Methods: Three test models (human cadavers A, B, and C) were prepared by removing supraspinal/interspinous ligaments between L4 and L5. The dental resin was attached to the cephalocaudal spinous process so that the spinous processes between L4 and L5 were almost in contact with each other to simulate the condition of a kissing spine. The flexion-extension direction's torque-range-of-motion (torque-ROM) curve was generated with a six-axis material tester for biomechanical measurements. Results: In all three models, the maximum ROMs at the time of extension were smaller than those at the time of flexion, and no sudden increase in torque was observed during extension. Conclusion: The results indicated no apparent biomechanical effects of kissing between the spinous processes, suggesting that the contact between the spinous processes has little involvement in the onset of lower back pain.

Atlanto-axial subluxation secondary to a neglected odontoid fracture.

A 81-year-old female had chronic renal failure and was undergoing hemodialysis, visited orthopaedic clinic after striking her head on the ceiling of a car while driving on a rough road. An odontoid fracture went unidentified on the initial radiograph. One month later, she came to our hospital with persistent neck pain. A radiography and computed tomography revealed a C1-two subluxation secondary to the fracture. Posterior occipito-C1-C2-C3 fixation was performed, and the patient wore a halo-vest for two-month post-surgery. After two months, the halo-vest was removed, and the patient was not experiencing any pain or neurological deficits. In older patients, even minor head trauma can result in cervical vertebral fractures. Therefore, potential fractures should be considered during initial evaluations to avoid the serious consequences of an incorrect initial diagnosis. Care should be taken when choosing between conservative or surgical treatments, considering all potential risks and complications.

En Bloc Resection for a Malignant Spine Tumor After Balloon Kyphoplasty: Histological Findings of a Retrieved Vertebral Body: A Case Report.

CASE: A 45-year-old woman with severe back pain underwent percutaneous curettage and balloon kyphoplasty (BKP) of a lesion believed to be aneurysmal bone cyst. Three months after BKP, local recurrence was observed, and the histological diagnosis was revised to malignant tumor. Thus, we performed a total en bloc spondylectomy, and the L3 vertebral body was resected. She was reconstructed by titanium expandable cage, rod, and pedicle screws. We observed viable tumor cells and foreign body reaction adjacent to the polymethylmethacrylate cement, carrying no bone necrosis. CONCLUSIONS: The long-term durability and safety of BKP for metastatic spine disease should be further clarified.

Transoral Mandibular Tongue-Splitting Approach in Upper Cervical Epidural Abscess: A Case Report and Review of the Literature.

INTRODUCTION: The transoral mandibular tongue-splitting approach is typically performed for the treatment of upper cervical tumor and instability but has not been performed for the treatment of upper cervical epidural abscess (UCEA). We report the first case of UCEA successfully treated with a transoral mandibular tongue-splitting approach. TECHNICAL NOTE: A 62-year-old man who had medical histories of tracheotomy with intubation and dermatopathy due to radiation therapy for the treatment of nasopharyngeal carcinoma presented with neck pain and limb weakness. The imaging examination revealed bone erosion of C2-C4 vertebrae and abscess at the level of C2-C4, supporting a diagnosis of UCEA. The transcervical approach could not be used for treatment; therefore, the transoral mandibular tongue-splitting approach was used successfully to perform decompression, debridement, and iliac bone grafting. Subsequently, we reviewed the literature pertaining to the use of the transoral mandibular tongue-splitting approach. The approach can be invasive and cause some complications. However, no fatal complications have been reported, and all patients demonstrated a favorable neurological outcome with reduced neurological deficits. CONCLUSIONS: This case and subsequent literature review suggest that the transoral mandibular tongue-splitting approach may be effective for the improvement of neurological outcomes without fatal complications in patients with UCEA. There may be an increasing number of patients with UCEA requiring the transoral mandibular tongue-splitting approach due to the increasing prevalence of immunocompromized status and the aging population.

Supratentorial subdural hemorrhage of a previous head injury and cerebellar hemorrhage after cervical spinal surgery: a case report and review of the literature.

STUDY DESIGN: Case report. OBJECTIVE: To report a case of an acute supratentorial subdural hemorrhage (SDH) of a previous head injury site and cerebellar hemorrhage, after an incidental dural tear during spine surgery. SUMMARY OF BACKGROUND DATA: Intracranial hemorrhage, such as subdural, cerebellar, subarachnoid, and epidural hemorrhage after a dural tear during spinal surgery, is a rare and poorly recognized complication. Moreover, only 3 cases in patients with concurrent SDH and cerebellar hemorrhage have been described in the literature, and none of these reports demonstrated the bleeding point on the adhesion site of the dural at the regions of the previous head injury. METHODS: A case report and literature review are presented. RESULTS: A 46-year-old male underwent occipital cervical surgery for os odontoideum. Intraoperatively, a dural tear was noted and repaired, but he later developed postoperative disturbance of consciousness. A head computed tomographic scan revealed a supratentorial SDH and cerebellar hemorrhage. Evacuation of the supratentorial SDH was performed via craniotomy, and the bleeding point was revealed to be on the adhesion site of the dural where the patient had experienced a previous head injury. The patient made a full recovery. CONCLUSION: This report illustrates that cerebrospinal fluid leakage after a dural tear during spinal surgery may cause intracranial hemorrhage. A previous head trauma could be a risk factor for such hemorrhagic complications. Headache, nausea, and postoperative stupor after spinal surgery, especially after an accidental durotomy, should be considered possible indications of intracranial hemorrhage, and affected patients should be investigated with computed tomography or magnetic resonance imaging. LEVEL OF EVIDENCE: N/A.