Diabetes increases risk of lumbar spinal fusion complications: association with altered structure of newly formed bone at the fusion site.

Diabetes predisposes to spine degenerative diseases often requiring surgical intervention. However, the statistics on the prevalence of spinal fusion success and clinical indications leading to the revision surgery in diabetes are conflicting. The purpose of the presented retrospective observational study was to determine the link between diabetes and lumbar spinal fusion complications using a database of patients (n = 552, 45% male, age 54 ± 13.7 years) residing in the same community and receiving care at the same health care facility. Outcome measures included clinical indications and calculated risk ratio (RR) for revision surgery in diabetes. Paravertebral tissue recovered from a non-union site of diabetic and nondiabetic patients was analyzed for microstructure of newly formed bone. Diabetes increased the RR for revision surgery due to non-union complications (2.80; 95% CI, 1.12-7.02) and degenerative processes in adjacent spine segments (2.26; 95% CI, 1.45-3.53). In diabetes, a risk of revision surgery exceeded the RR for primary spinal fusion surgery by 44% (2.36 [95% CI, 1.58-3.52] vs 1.64 [95% CI, 1.16-2.31]), which was already 2-fold higher than diabetes prevalence in the studied community. Micro-CT of bony fragments found in the paravertebral tissue harvested during revision surgery revealed structural differences suggesting that newly formed bone in diabetic patients may be of compromised quality, as compared with that in nondiabetic patients. In conclusion, diabetes significantly increases the risk of unsuccessful lumbar spine fusion outcome requiring revision surgery. Diabetes predisposes to the degeneration of adjacent spine segments and pseudoarthrosis at the fusion sites, and affects the structure of newly formed bone needed to stabilize fusion.

A clinical review of hand manifestations of cervical myelopathy, cervical radiculopathy, radial, ulnar, and median nerve neuropathies.

Cervical spondylotic myelopathy (CSM) is defined as compression of the spinal cord in the neck, resulting in problems with fine motor skills, hand numbness, pain or stiffness of the neck, and difficulty walking due to loss of balance. Brachial plexus (BP) neuropathies arise due to compression to any distal branches arising from C5-T1, whereas cervical radiculopathy involves compression at the nerve root in the neck. Such conditions can present with variable degrees of musculoskeletal pain, weakness, sensory changes, and reflex changes. The pronounced convergence in symptomatic manifestation within these conditions can pose a formidable challenge to clinicians, particularly in primary care. Thus, the primary objective of this paper is to enhance clarity and distinction among these pathological conditions. This objective is pursued through comprehensive delineation of the dermatomal and myotomal distributions characteristic of each condition. Furthermore, a meticulous examination is undertaken to elucidate physical indicators and maneuvers that exhibit a notably high sensitivity in detecting these conditions. Accurate diagnosis and treatment of each nerve pathology is important as long-term spinal cord compression and its roots may result in permanent disability and severely impact one's quality of life. As such, this systematic review serves as a guide that aids clinicians in differentiating the aforementioned conditions based on anatomy, physical exam findings, and imaging studies. Furthermore, this study aims to outline common peripheral nerve neuropathies in the upper extremities and ways to mitigate these pathologies using the least to most invasive treatment modalities.

Spondyloarthropathies That Mimic Ankylosing Spondylitis: A Narrative Review.

Ankylosing spondylitis is the most common type of seronegative inflammatory spondyloarthropathy often presenting with low back or neck pain, stiffness, kyphosis and fractures that are initially missed on presentation; however, there are other spondyloarthropathies that may present similarly making it a challenge to establish the correct diagnosis. Here, we will highlight the similarities and unique features of the epidemiology, pathophysiology, presentation, radiographic findings, and management of seronegative inflammatory and metabolic spondyloarthropathies as they affect the axial skeleton and mimic ankylosing spondylitis. Seronegative inflammatory spondyloarthropathies such as psoriatic arthritis, reactive arthritis, noninflammatory spondyloarthropathies such as diffuse idiopathic skeletal hyperostosis, and ochronotic arthritis resulting from alkaptonuria can affect the axial skeleton and present with symptoms similar those of ankylosing spondylitis. These similarities can create a challenge for providers as they attempt to identify a patient's condition. However, there are characteristic radiographic findings and laboratory tests that may help in the differential diagnosis. Axial presentations of seronegative inflammatory, non-inflammatory, and metabolic spondyloarthropathies occur more often than previously thought. Identification of their associated symptoms and radiographic findings are imperative to effectively diagnose and properly manage patients with these diseases.

Effects of Sacral Slope Changes on the Intervertebral Disc and Hip Joint: A Finite Element Analysis.

OBJECTIVE: Spinopelvic parameters are vital components that must be considered when treating patients with spinal disease. Several finite element (FE) studies have explored spinopelvic parameters such as sacral slope (SS) and the impact on the lumbar spine, although no study has examined the effect on the hip and sacroiliac joint (SIJ) on varying SS angles. Therefore, it is necessary to have a biomechanical understanding of the impact on the spinopelvic complex. METHODS: An FE lumbar, pelvis, and femur model was created from computed tomography scans of a 55-year-old female patient with no abnormalities. Three models were created: a normal model (SS = 26°), a model with high SS (SS = 30°), and a model with low SS (SS = 20°). These models underwent loading for flexion, extension, lateral bending, and axial rotation. Range of motion (ROM), intradiscal pressures, hip joint, and SIJ contact stresses were analyzed. RESULTS: The high SS model (SS = 30°) indicated the highest ROM in the L5-S1 (slip angle) level and the highest intradiscal pressures. The highest average hip and SIJ contact stresses were present in this model, although the low SS model (SS = 20°) in extension had the largest stresses for the hip and SIJ. CONCLUSIONS: The results provide evidence that patients with higher SS may be more prone to increased ROM at the slip angle (L5-S1). In addition, patients with higher SS were shown to have higher contact stresses on the hip joint and SIJ, potentially leading to SIJ dysfunction. Clinically, correcting lumbar lordosis including SS is important; however, a high SS may have a negative impact on the intervertebral disc, SIJ, and hip joint.

Pedicle Screw Track Augmentation With Fibular Allograft for Significant Bone Loss in Revision Fixation.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To report the clinical and radiological outcomes for screw track augmentation with fibular allograft in revision of loose pedicle screws associated with significant bone loss along the screw track. METHODS: Thirty consecutive patients, 18 men (60%) and 12 women (40%), with a mean age 52 years (range 34- 68). Fibular allograft was prepared by cutting it into longitudinal strips 50 mm in length. Three allograft struts were inserted into the screw track. Six mm tap used to tap between the 3 fibular struts. Eight- or 9-mm diameter, and 45 or 50 mm in length screw was then inserted. The clinical outcomes were assessed by means of the Oswestry Disability Index (ODI), and visual analog scale (VAS) for back and leg pain for clinical outcome. Computed tomography scan (CT) performed at 12 months postoperative visit to assess fibular graft incorporation along the pedicle screw track, any screw loosening and the interbody as well as posterolateral fusion. RESULTS: At a mean follow up of 29 months, there were statically significant improvement in the ODI and VAS for back and leg pain. CT scan obtained at last follow-up showed incorporation of fibular allograft and solid fusion in all patients except one. CONCLUSION: The fibular allograft augmentation of the pedicle screw track in revision of loose pedicle screws associated with significant bone loss is a viable option. It allows for biologic fixation at the screw-bone interface and has some key advantages when compared to currently available methods.

Intracranial hemorrhage after spinal surgery: a literature review.

Background and Objective: Intracranial hemorrhage following spinal surgery is an infrequent but severe complication. Due to its rarity, the etiology, clinical characteristics, and treatment have not yet been fully elucidated. This literature review analyzed the incidence, clinical manifestations, hemorrhage location, current therapeutic strategies, location of operation, and interval time between surgery and bleeding. The objectives of the article were to provide insights for clinicians to promptly identify and prevent potential cases of intracranial hemorrhage. Methods: The authors queried PubMed and Web of Science databases using predefined keywords and included published literature reporting on intracranial hemorrhage after spinal surgery. Relevant case reports, case series, and reviews describing the mechanism of intracranial hemorrhage after spinal surgery and meeting diagnostic criteria for intracranial hemorrhage related to spinal surgery were included. Clinico-demographc data, presentations symptoms, location, index surgery type, and neurological outcomes after brain hemorrhage. Oxford Centre Level of Evidence guidelines was used to evaluate the quality of included studies. Descriptive statistics were used to synthesize the results. Key Content and Findings: A total of 80 publications of level of evidence IV involving 108 patients with median age at diagnosis was 58.5 years (inter-quartile range: 6-85) were analyzed. The incidence of intracranial hemorrhage was 0.08-0.37% among patients who underwent spinal surgery, and this complication occurred predominantly within 48 hours postoperatively. The initial presentation included headache, reduced level of consciousness, dysarthria, nausea, vomiting, hearing loss, blurred vision, neck rigidity, and delayed recovery from anesthesia. More than half (58.3%) of patients improved, while 23.1% still experienced neurological dysfunctions, and 7.4% died. Conclusions: The present study is limited by the levels of evidence of the included studies. There is heterogeneity among cases with respect to patient demographics and medical history. Angiography is critical in assessing the presence and extent of underlying vascular diseases. Intracranial hemorrages may be caused by intraoperative or postoperative cerebrospinal fluid leakage that will lead to intracranial pressure change and induced by intracranial venous or arterial bleeding. The treatment strategies include conservative medical management and surgical treatment. Individualized treatment should be emphasized.

Clinical presentation and surgical anatomy of sympathetic nerve injury during lumbar spine surgery: a narrative review.

Background and Objective: To highlight the surgical anatomy, procedural variations, presentation, and management of sympathetic nerve injury after surgery of the lumbar spine. Methods: PubMed and Google Scholar were searched for publications that were completed between 1951 and 2021. Relevant full-text articles published in the English language were selected and critically reviewed. Key Content and Findings: Sympathetic injury is a highly variable postsurgical complication with a greater incidence after an anterior or oblique approach to the lumbar spine compared to posterior and lateral approaches. The direct and extreme lateral approaches reduce the need to disturb sympathetic nerves thus reducing the risk of complications. It can present in multiple manners, including complex regional pain syndrome (CRPS) and retrograde ejaculation. These complications can be transient and resolve spontaneously or be treated with medications, physical therapy, and spinal blocks. The severity of the conditions and extent of recovery can vary drastically, with some patients never fully recovering. Conclusions: To access the lumbar spine, there are operational approaches and techniques that should be used to decrease the risk of intraoperative injury. It is crucial to understand the advantages and risks to different approaches and take the necessary steps to minimize complications. Early identification of dysfunction and adequate management of symptoms are imperative to effectively manage patients with lumbar sympathetic trunk and sympathetic nerve fiber injuries.

Lumbar spine fusion outcomes using a cellular bone allograft with lineage-committed bone-forming cells in 96 patients.

BACKGROUND: Instrumented posterior lumbar fusion (IPLF) with and without transforaminal interbody fusion (TLIF) is a common treatment for low back pain when conservative interventions have failed. Certain patient comorbidities and lifestyle risk factors, such as obesity and smoking, are known to negatively affect these procedures. An advanced cellular bone allograft (CBA) with viable osteogenic cells (V-CBA) has demonstrated high fusion rates, but the rates for patients with severe and/or multiple comorbidities remain understudied. The purpose of this study was to assess fusion outcomes in patients undergoing IPLF/TLIF using V-CBA with baseline comorbidities and lifestyle risk factors known to negatively affect bone fusion. METHODS: This was a retrospective study of de-identified data from consecutive patients at an academic medical center who underwent IPLF procedures with or without TLIF, and with V-CBA. Baseline patient and procedure characteristics were assessed. Radiological outcomes included fusion rates per the Lenke scale. Patient-reported clinical outcomes were evaluated via the Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) for back and leg pain. Operating room (OR) times and intraoperative blood loss rates were also assessed. RESULTS: Data from 96 patients were assessed with a total of 222 levels treated overall (mean: 2.3 levels) and a median follow-up time of 16 months (range: 6 to 45 months). Successful fusion (Lenke A or B) was reported for 88 of 96 patients (91.7%) overall, including in all IPLF-only patients. Of 22 patients with diabetes in the IPLF+TLIF group, fusion was reported in 20 patients (90.9%). In IPLF+TLIF patients currently using tobacco (n = 19), fusion was reported in 16 patients (84.3%), while in those with a history of tobacco use (n = 53), fusion was observed in 48 patients (90.6%). Successful fusion was reported in all 6 patients overall with previous pseudarthrosis at the same level. Mean postoperative ODI and VAS scores were significantly reduced versus preoperative ratings. CONCLUSION: The results of this study suggest that V-CBA consistently yields successful fusion and significant decreases in patient-reported ODI and VAS, despite patient comorbidities and lifestyle risk factors that are known to negatively affect such bony healing.

Iatrogenic muscle damage in transforaminal lumbar interbody fusion and adjacent segment degeneration: a comparative finite element analysis of open and minimally invasive surgeries.

PURPOSE: Lumbar procedures for Transforaminal Lumbar Interbody Fusion (TLIF) range from open (OS) to minimally invasive surgeries (MIS) to preserve paraspinal musculature. We quantify the biomechanics of cross-sectional area (CSA) reduction of paraspinal muscles following TLIF on the adjacent segments. METHODS: ROM was acquired from a thoracolumbar ribcage finite element (FE) model across each FSU for flexion-extension. A L4-L5 TLIF model was created. The ROM in the TLIF model was used to predict muscle forces via OpenSim. Muscle fiber CSA at L4 and L5 were reduced from 4.8%, 20.7%, and 90% to simulate muscle damage. The predicted muscle forces and ROM were applied to the TLIF model for flexion-extension. Stresses were recorded for each model. RESULTS: Increased ROM was present at the cephalad (L3-L4) and L2-L3 level in the TLIF model compared to the intact model. Graded changes in paraspinal muscles were seen, the largest being in the quadratus lumborum and multifidus. Likewise, intradiscal pressures and annulus stresses at the cephalad level increased with increasing CSA reduction. CONCLUSIONS: CSA reduction during the TLIF procedure can lead to adjacent segment alterations in the spinal element stresses and potential for continued back pain, postoperatively. Therefore, minimally invasive techniques may benefit the patient.

High Prevalence of Biofilms on Retrieved Implants from Aseptic Pseudarthrosis Cases.

INTRODUCTION: Recent literature has associated pseudarthrosis and pedicle screw loosening with subchronic infection at the pedicle of the vertebra. The positive culture results of a previous retrieval analysis show that such patients have a high frequency of bacterial contamination. The objective of this study is to visually capture the architecture of these undiagnosed infections, which have been described in other studies as biofilms on supposedly "aseptic" screw loosening. METHODS: Explants from 10 consecutive patients undergoing revision spine surgery for pseudarthrosis were collected and fixed in glutaraldehyde solution. Each of these implants was imaged thoroughly by using scanning electron microscopy and x-ray spectroscopy to evaluate the architecture of the biofilm. Additionally, eight patient swabs from tissues around the implants were sent for cultures to assess bacterial infiltration in tissues beyond the biofilm. The implants were also analyzed using energy dispersive x-ray spectroscopy. The exclusion criteria included clinically diagnosed infection (current or previous) and/or mechanical failure of the implant due to falls/accidents. RESULTS: The study was successful in capturing the visual architecture of the biofilm on retrieved implants. A total of 77% of pseudarthrosis cases presented with loose pedicle screws, which were diagnosed by a preoperative computed tomography scan showing radiolucency along the screw track and were confirmed intraoperatively, and 72% of the cases showed biofilm on explants. CONCLUSIONS: In the absence of the clinical presentation of infection, impregnated bacteria could form a biofilm around an implant, and this biofilm can remain undetected via contemporary diagnostic methods, including swabbing. Implant biofilm is frequently present in "aseptic" pseudarthrosis cases.

Overreporting of the disc herniation in lumbar spine MRI scans performed for patients with spondylolisthesis.

BACKGROUND: Spondylolisthesis is often misdiagnosed on magnetic resonance imaging (MRI) as the slip may reduce to a normal alignment when the patient lies supine. Often, disc herniation is reported at the level of spondylolisthesis. PURPOSE: To determine the incidence rates of disc herniation at the level of spondylolisthesis. MATERIAL AND METHODS: This is a retrospective study included 258 consecutive patients with spondylolisthesis who had lumbar spine MRI. The archived reports were collectively put in Group 1. A musculoskeletal radiologist and a spine surgeon reviewed the imaging studies together. Their readings were referred to as Group 2. The findings of both groups were compared to evaluate whether disc herniation was overreported. RESULTS: Group 1 reported findings of true disc herniation in 112 (41.6%) cases and pseudo disc herniation or no findings of disc herniation at the level of spondylolisthesis in 157 (58.4%) cases. Group 2 reported findings of a true disc herniation in 25 (9.3%) cases and pseudo disc herniation or no findings of disc herniation in the remaining 244 (90.7%) cases. There was a statistically significant difference in the reporting rates between these two groups (P < 0.02). The most overreported finding was the disc bulging (P < 0.01). CONCLUSION: The current study showed overreporting of disc herniation in lumbar spine MRI scans performed for patients with established spondylolisthesis. The majority of disc pathology at the level of spondylolisthesis are pseudo disc rather than a true disc herniation. An accurate diagnosis is vital in planning surgical intervention.

Biomechanics of the Sacroiliac Joint: Surgical Treatments.

BACKGROUND: Fixation is one of the most common surgical techniques for the treatment of chronic pain originating from the sacroiliac joint (SIJ). Many studies have investigated the clinical outcomes and biomechanics of various SIJ surgical procedures. However, the biomechanical literature points to several issues that need to be further explored, especially for the devices used in minimally invasive surgery of the SIJ. This study (part II) aims to assess biomechanical literature to understand the existing information as it relates to efficacies of the surgical techniques and the gaps in the knowledge base. Part I reviewed basic anatomy and mechanics of the SIJ joint, including difference between males and females, and causes of pain emanating from these joints. METHODS: A thorough literature review was performed pertaining to studies related to SIJ fixation techniques and the biomechanical outcomes of the surgical procedures. RESULTS: Fifty-five studies matched the search criteria and were considered for the review. These articles predominantly pertained to the biomechanical outcomes of the minimally invasive surgery with different instrumentation systems and surgical settings. CONCLUSIONS: The SIJ is one of the most overlooked sources of lower back pain. The joint is responsible for the pain in 15% to 30% of people suffering from lower back pain. Various studies have investigated the clinical outcomes of different surgical procedures intended to improve the pain and quality of life following surgery. The data show that these techniques are indeed effective. However, clinical studies have raised several issues, like optimal number and positioning of implants, unilateral versus bilateral placements, adjacent segment disease, implant designs, and optimal location of implants with respect to variations in bone density across the SIJ. Biomechanical studies using in vitro and in silico techniques have addressed some of these issues. Studies also point out the need for additional investigations for a better understanding of the underlying mechanics for the improved long-term surgical outcomes. Further long-term clinical follow-ups are essential as well. This review presents pertinent findings.

Updates on Evidence-Based Practices to Reduce Preoperative and Intraoperative Contamination of Implants in Spine Surgery: A Narrative Review.

The current communication seeks to provide an updated narrative review on latest methods of reducing implant contaminations used during spine surgery. Recent literature review has shown that both preoperative reprocessing and intraoperative handling of implants seem to contaminate implants. In brief, during preoperative phase, the implants undergo repeated bulk cleaning with dirty instruments from the OR, leading to residue buildup at the interfaces and possibly on the surfaces too. This, due to its concealed nature, remains unnoticed by the SPD (sterile processing department) or other hospital staff. Nevertheless, these can be avoided by using individually prepackaged presterilized implants. In the intraoperative phase, the implants (in the sterile field) are directly touched by the scrub tech with soiled (assisting the surgeon dispose the tissues from the instruments in use) gloves for loading onto an insertion device. It is then kept exposed on the working table (either separately or next to the used instruments as the pedicles hole are being prepared). Latest investigation has shown that by the time it is implanted in the patient, it can harbor up to 10e7 bacterial colony-forming units. The same implants were devoid of such colony-forming units, when sheathed by an impermeable sterile sheath around the sterile implant.

Biomechanics of the Sacroiliac Joint: Anatomy, Function, Biomechanics, Sexual Dimorphism, and Causes of Pain.

BACKGROUND: The sacroiliac joints (SIJs), the largest axial joints in the body, sit in between the sacrum and pelvic bones on either side. They connect the spine to the pelvis and thus facilitate load transfer from the lumbar spine to the lower extremities. The majority of low back pain (LBP) is perceived to originate from the lumbar spine; however, another likely source of LBP that is mostly overlooked is the SIJ. This study (Parts I and II) aims to evaluate the clinical and biomechanical literature to understand the anatomy, biomechanics, sexual dimorphism, and causes and mechanics of pain of the SIJ leading to conservative and surgical treatment options using instrumentation. Part II concludes with the mechanics of the devices used in minimal surgical procedures for the SIJ. METHODS: A thorough review of the literature was performed to analyze studies related to normal SIJ mechanics, as well as the effects of sex and pain on SIJ mechanics. RESULTS: A total of 65 studies were selected related to anatomy, biomechanical function of the SIJ, and structures that surround the joints. These studies discussed the effects of various parameters, gender, and existence of common physiological disorders on the biomechanics of the SIJ. CONCLUSIONS: The SIJ lies between the sacrum and the ilium and connects the spine to the pelvic bones. The SIJ transfers large bending moments and compression loads to lower extremities. However, the joint does not have as much stability of its own against the shear loads but resists shear due the tight wedging of the sacrum between hip bones on either side and the band of ligaments spanning the sacrum and the hip bones. Due to these, sacrum does not exhibit much motion with respect to the ilium. The SIJ range of motion in flexion-extension is about 3°, followed by axial rotation (about 1.5°), and lateral bending (about 0.8°). The sacrum of the female pelvis is wider, more uneven, less curved, and more backward tilted, compared to the male sacrum. Moreover, women exhibit higher mobility, stresses/loads, and pelvis ligament strains compared to male SIJs. Sacroiliac pain can be due to, but not limited to, hypo- or hypermobility, extraneous compression or shearing forces, micro- or macro-fractures, soft tissue injury, inflammation, pregnancy, adjacent segment disease, leg length discrepancy, and prior lumbar fusion. These effects are well discussed in this review. This review leads to Part II, in which the literature on mechanics of the treatment options is reviewed and synthesized.

A Multicenter Trial Demonstrating Presence or Absence of Bacterial Contamination at the Screw-Bone Interface Owing to Absence or Presence of Pedicle Screw Guard, Respectively, During Spinal Fusion.

STUDY DESIGN: A prospective multicenter study. OBJECTIVE: The objective of this study was to assess bacterial contamination in current practices of pedicle screw handling and comparing it to a novel method of using an intraoperative, sterile implant guard for screws. SUMMARY OF BACKGROUND DATA: Postoperative infections occur at the higher end of 2%-13%, as cited in the literature, and are underestimated due to various reasons in such publications. Despite concerns associated with vancomycin application immediately before closure, it is theoretically impossible to irrigate the screw-bone interface postimplantation. Consequently, any contamination of pedicle screw before implantation is permanent, and has the potential to cause deep-bone infection, or hardware loosening due to encapsulation of biofilm between the bone and the screw. Therefore, continued vigilance and effective preventive measures should be undertaken if available. MATERIALS AND METHODS: Two groups of presterile individually-packaged pedicle screws, one incased in a sterile, protective guard (group 1: G) and the other without such a guard (group 2: NG), 31 samples in each group were distributed over 28 spinal fusion surgeries at 5 independent hospitals groups. Each were loaded onto the insertion device by the scrub tech and left on the sterile table. Twenty minutes later, the lead surgeon who had just finished preparing the surgical site, handles the pedicle screw, to check the fit with the insertion device. Then, instead of implantation, it was transferred to a sterile container using fresh sterile gloves for bacterial analysis. RESULTS: The standard unguarded pedicle screws presented bioburden in the range of 10 to 10 colonies forming units per screw, whereas the guarded pedicle screws showed no bioburden. CONCLUSION: Standard, current, handling of pedicle screws leads to bacterial contamination, which can be avoided if the screws are sterilely prepackaged with an intraoperative guard (preinstalled).

Fracture of allograft interbody spacer resulting in post-operative radiculopathy: A case report.

BACKGROUND: Allograft interbody spacers are utilized during transforaminal lumbar interbody fusion (TLIF) to reestablish anterior column support and disc height. While the TLIF technique offers many improvements over previous surgical methods, instrumentation and bone graft-related complications such as spacer misplacement or migration, screw fracture or misplacement, or rod breakage continue to be reported. The objective of this manuscript is to report on a fractured allograft interbody spacer that displaced into the neural foramen and resulted in impingement on the exiting nerve root that required revision. CASE SUMMARY: A 50-year-old male had two-level TLIF with immediate post-operative right L5 radiculopathy. Computed tomography scan demonstrated a fractured allograft interbody spacer that displaced into the right neural foramen and impinged on the exiting L5 nerve root. Revision surgery was performed to remove the broken allograft fragments from the right L5 foramen and the intact portion of the spacer was left in place. The right leg L5 radicular pain resolved. At the last follow up 12 mo after the index procedure, computed tomography scan confirmed sound interbody and posterolateral fusion. CONCLUSION: Displacement of broken allograft interbody spacer following TLIF procedures can result in neurological sequelae that require revision. To avoid such an occurrence, the authors recommend allowing sufficient time for the reconstitution of the graft in saline prior to use to decrease brittleness, to use an impactor size that is as close as possible to the spacer size and meticulous inspection of the cortical allograft spacer for any visible imperfection prior to insertion.

Analysis of a ten step protocol to decrease postoperative spinal wound infections.

AIM: To define a ten-step protocol that reduced the incidence of surgical site infection in the spine surgery practice of the senior author and evaluate the support for each step based on current literature. METHODS: In response to unexplained increased infection rates at our institution following spine surgery, a ten-step protocol was implemented: (1) preoperative glycemic management based on hemoglobin A1c (HbA1c); (2) skin site preoperative preparation with 2% chlorhexidine gluconate disposable cloths; (3) limit operating room traffic; (4) cut the number of personnel in the room to the minimum required; (5) absolutely no flash sterilization of equipment; (6) double-gloving with frequent changing of outer gloves; (7) local application of vancomycin powder; (8) re-dosing antibiotic every 4 h for prolonged procedures and extending postoperative coverage to 72 h for high-risk patients; (9) irrigation of subcutaneous tissue with diluted povidone-iodine solution after deep fascial closure; and (10) use of DuraPrep skin preparation at the end of a case before skin closure. Through an extensive literature review, the current data available for each of the ten steps was evaluated. RESULTS: Use of vancomycin powder in surgical wounds, routine irrigation of surgical site, and frequent changing of surgical gloves are strongly supported by the literature. Preoperative skin preparation with chlorhexidine wipes is similarly supported. The majority of current literature supports control of HbA1c preoperatively to reduce risk of infection. Limiting the use of flash sterilization is supported, but has not been evaluated in spine-specific surgery. Limiting OR traffic and number of personnel in the OR are supported although without level 1 evidence. Prolonged use of antibiotics postoperatively is not supported by the literature. Intraoperative use of DuraPrep prior to skin closure is not yet explored. CONCLUSION: The ten-step protocol defined herein has significantly helped in decreasing surgical site infection rate. Several of the steps have already been shown in the literature to have significant effect on infection rates. As several measures are required to prevent infection, instituting a standard protocol for all the described steps appears beneficial.

Biomechanical analysis on of anterior transpedicular screw-fixation after two-level cervical corpectomy using finite element method.

BACKGROUND: Anterior cervical trans-pedicle screw fixation was introduced to overcome some of the disadvantages associated with anterior cervical corpectomy and fusion. In vitro biomechanical studies on the trans-pedicle screw fixation have shown excellent pull-out strength and favorable stability. Comprehensive biomechanical performance studies on the trans-pedicle screw fixation, however, are lacking. METHODS: The control computed tomography images (C2-T2) were obtained from a 22-year-old male volunteer. A three dimensional computational model of lower cervical spine (C3-T1) was developed using computed tomography scans from a 22 year old human subject. The models of intact C3-T1 (intact group), anterior cervical trans-pedicle screw fixation (trans-pedicle group), and anterior cervical corpectomy and fusion (traditional group) were analyzed with using a finite element software. A moment of 1 N·m and a compressive load of 73.6 N were loaded on the upper surface and upper facet joint surfaces of C3. Under six conditions, four parameters such as the range of motion, titanium mesh plant stress, end-plate stress, and bone-screw stress were measured and compared on two treatment groups. FINDINGS: Compared with the intact model, the range of motions for treatment groups were decreased. Compared with cervical corpectomy and fusion, the titanium plant, C4 upper end-plate and C7 lower end-plate stresses in trans-pedicle group were reduced. No significant difference was discovered on bone-screw stress between the two groups for lateral flexion and rotation, but bone-screw stress is smaller in trans-pedicle group when compared with traditional group. With exception of individual difference, trans-pedicle group had better biomechanical results than traditional group in range of motions, titanium mesh plant stress, end-plate stress and bone-screw stress. INTERPRETATION: The trans-pedicle method has better biomechanical properties than the anterior cervical corpectomy and fusion making it a viable alternative for cervical fixations.

Spondylolysis and spondylolisthesis: A review of the literature.

Spondylolysis is a common diagnosis with a high prevalence in children and adolescents complaining of low back pain. It may be caused by either a defect or fracture of the pars interarticularis due to mechanical stress. Depending on the severity of the spondylolysis and symptoms associated it may be treated either conservatively or surgically, both of which have shown significant success. Conservative treatments such as bracing and decreased activity have been shown to be most effective with patients who have early diagnosis and treatment. Low-intensity pulsed ultrasound (LIPUS) in addition to conservative treatment appears to be very promising for achieving a higher rate of bony union. LIPUS requires more supporting studies, but may prove to become a standard of care in the future. Surgery may be required if conservative treatment, for at least six months, failed to give sustained pain relief for the activities of daily living. Based on studies performed on each of the major surgical treatments we suggest the use of the pedicle screw hook technique and the pedicle screw rod technique due to low rates of hardware failure, increased maintenance of mobility, and lack of a postoperative bracing requirement.