Tarush Rustagi

Lateral Transpsoas Approach to the Lumbar Spine and Relationship of the Ureter: Anatomic Study with Application to Minimizing Complications

BACKGROUND Complications from lateral lumbar interbody fusion procedures range from neurologic deficits to organ and blood vessel injuries. Injury to the ureter has been reported though uncommon. The present study was performed to elucidate the anatomic relationship of the ureter to this surgical approach. METHODS Eight adult cadavers (16 sides) were placed in the full lateral position, and the distal ureter was cannulated with a metal wire that was passed up to the kidney. Fluoroscopy was used to establish the position of the ureter in relation to the bony anatomy in this region. RESULTS In the lumbar region, there was a posterior to anterior course of the left and right ureter. From the direct lateral position, the ureter was found to lie at or posterior to the anterior edge of the lumbar vertebral bodies. On 87.5% of sides, the ureter was on average 2.5 cm posterior to the anterior border of the vertebral bodies at L2, 3 cm posterior at L3, 1.0 cm posterior at L4, and on the margin of the anterior vertebral bodies at L5. In general, the ureter, from a lateral perspective, crossed the posterior third of the upper lumbar vertebrae, approached the middle third at L3, and reached the anterior third at L4/L5 before descending into the pelvis. CONCLUSIONS Owing to the proximity of the ureter to the lumbar vertebral bodies, it is imperative to verify that this structure is not in the surgical trajectory during lateral lumbar interbody fusion procedures if injury is to be avoided.

Adult Apical Ligament of the Dens Lacks Notochordal Tissue: Application to Better Understanding the Origins of Skull Base Chordomas

INTRODUCTION The apical ligament has long been reported to contain notochord remnants and thus might serve as a site of origin of chordoma formation at the skull base. However, to our knowledge, the histologic study of the apical ligament using histologic staining specific for notochordal tissue has not been previously performed. Therefore the current study was undertaken. METHODS Fifteen apical ligament samples underwent histologic examination with specific markers for notochordal differentiation. RESULTS Across all samples, there was no indication of any notochordal remnants. CONCLUSIONS On the basis of our cadaveric study, the apical ligament does not contain notochord tissue and in adults should not be considered a remnant of this structure. Moreover, it is unlikely that the apical ligament gives rise to chordomas at the craniocervical junction under normal circumstances.

The Decussating Fibers of the Lumbar Thoracolumbar Fascia: A Landmark for Identifying the L5 Spinous Process?

BACKGROUND The thoracolumbar fascia (TLF) has been well studied and is known to have crisscrossing fibers. Based on surgical experience, we hypothesized that the decussating fibers of the TLF may indicate a specific vertebral level and performed an anatomic study. METHODS Twenty adult fresh frozen cadavers aged 72-84 years at death were placed in the prone position, and the skin of the lumbar and upper sacrum was removed. Careful attention was given to the TLF and any fibers of it that grossly crossed the midline to interdigitate with its contralateral counterpart. Once such decussations were identified, a metal wire was laid on them at their center, and fluoroscopy was performed to verify the vertebral level. RESULTS Decussating fibers of the TLF were found on all but 1 specimen (95%). The central part of the decussation on the midline corresponded to the spinous process of L5 in 17/19 (89%) of specimens and the lower edge (L4-L5 interspace) of the spinous process of L4 in the remaining 2 specimens (11%). No specimens were found to have previous surgery in the area dissected or congenital anomalies of the spine. CONCLUSIONS In our cadaveric study, the decussating fibers of the TLF in the lumbar region helped predict the L5 spinous process in 89% of specimens and the L4 spinous process in 11% of specimens. This anatomic landmark might be used as an adjunct to palpation and intraoperative imaging during surgical exploration of the lower lumbar region.

Failure Patterns in Standalone Anterior Cervical Discectomy and Fusion Implants

BACKGROUND Anterior cervical discectomy and fusion is commonly performed using an allograft or autograft implant and anterior screw-supported plate. There has been an increase in the use of standalone cage devices due to ease of use and studies suggesting a lower rate of acute postoperative dysphagia. We review our experience with standalone cage devices and identify risk factors, patterns of failure, and revision surgery approaches. METHODS We performed a retrospective case series of patients treated at a single tertiary care institution between March 2014 and March 2015. Inclusion criteria were aged 18-100 years, 1- or 2-level anterior cervical discectomy and fusion with a standalone cervical cage. Data collected included demographics, comorbidities, Charlson comorbidity score, primary diagnosis, and surgical characteristics. Descriptive statistics were performed for risk of readmission, implant failure, revision, and other complications. RESULTS We identified 211 patients who met our study criteria. Average surgical time was 107 ± 43 minutes, with an estimated blood loss of 84.6 ± 32.4 mL. There were 11 (5.2%) readmissions. There were 10 (4.74%) implant failures (5 involving single-level surgery and 5 involving 2-level surgery), with 7 cases of pseudoarthrosis. Mechanisms of failure included a C5 body fracture, fusion in a kyphotic alignment after graft subsidence, and acute spondylolisthesis. CONCLUSIONS Revision surgery after standalone anterior cervical implants can be complex. Posterior cervical fusion remains a valuable approach to avoid possible vertebral body fracture and loss of fusion area associated with the removal of implants secured through the endplates of adjacent vertebral bodies.

Bone morphogenic proteins are a good choice for select spinal surgeries and merit further research

Autologous bone graft with bone obtained from the iliac crest has long been used in spinal fusion surgery (1). Reports of morbidity associated with harvesting iliac crest bone graft (ICBG) have led to an ongoing quest for bone graft substitutes. Ever since Urist introduced the use of bone morphogenic protein (BMP) in 1960, BMPs have been the subject of debate and various research projects (2). BMP-2 (Infuse, Medtronics) has been FDA approved for anterior lumbar interbody fusion. BMP-7 [Osigraft (OS) and OP1 Putty, Stryker] has only been granted a Humanitarian exemption for revision posterolateral fusion in compromised patients.

Trends in Spinal Surgery for Pott’s Disease (2000-2016): An Overview and Bibliometric Study

Study Design: Systematic review. Objectives: (1) What are the surgical indications? Have they changed over time since the year 2000? (2) What is the current surgical approaches of choice? Have they changed over time since the year 2000? Do they vary by geographical region? (3) What are the most common outcome measures following surgery? Methods: Electronic databases and reference lists of key articles were searched from database inception from January 1, 2000 to December 31, 2016 to identify studies specifically evaluating surgical indications, current surgical approaches, and outcome measures for spinal tuberculosis. Results: Six randomized controlled trials were identified from our search (1 excluded: no surgical arm identified after review) Neurological deficit, instability and deformity were common indications identified. Surgical approach included predominantly anterior for cervical spine and posterior for thoracic and lumbar spine. Combined approach was preferred in pediatric cases. Degree of deformity correction, neurological outcomes, and fusion formed the main bases of assessing surgical outcomes. Conclusions: Majority of the current literature is from South Asia. The presence of neurological compromise, deformity, and instability were the primary criteria for surgical intervention. The preferred approach varied with the anatomical region of the spine in adults. Outcome measures predominantly involved deformity correction, neurological deficit, and fusion.

Autologous Bone Harvest in Anterior Cervical Spine Surgery: A Quantitative and Qualitative In Vitro Analysis of Cadaveric Tissue

BACKGROUND The cervical spine may be used as a harvesting site of local autograft material during anterior cervical discectomy and fusion procedures. We analyzed the quality and composition of bone grafts obtained from different parts of the cervical vertebrae in a cadaveric model. METHODS Five fresh adult human cadavers with intact cervical spines were used. Using a Smith-Robinson anterior approach to expose C4-5 and C5-6 vertebrae, samples from 4 vertebral sites were harvested under a microscope. Anterior osteophytes were removed piecemeal by a Leksell rongeur (sample A). A high-speed burr was used to drill the endplates of C4-5 and C5-6 (sample C) and uncovertebral joints of C4-5 (sample B) and C5-6 (sample D). Then 20 slides (4 per cadaver) were prepared and analyzed. RESULTS Tissue fragmentation was associated with use of the high-speed burr. Sample A had minimal tissue fragmentation. Samples B-D showed moderate to high fragmentation. Cartilage was found in all samples. Of the 20 slides, 6 contained soft tissues (sample A in 4, sample D in 2). Disc material was identified in 6 slides (sample A in 1, sample B in 4, sample D in 1). Sample A had the greatest number of intact osteocytes and chondrocytes, and sample B had the least. CONCLUSIONS Anterior osteophytes provide the highest number of osteocytes, with the highest osteocyte/chondrocyte ratio. Osteocyte viability is a function of vertebral body site and collection technique, with fragmentation caused by use of a high-speed burr decreasing the number of viable osteocytes.

Rapid Progression of Ossification of the Posterior Longitudinal Ligament After Anterior Cervical Discectomy and Fusion

BACKGROUND Ossification of the posterior longitudinal ligament (OPLL) has a reported incidence of 1.9%-4.3%. Disease progression is associated with surgery, with most studies focusing on OPLL progression after laminoplasty. The continued range of motion following surgery is believed to place strain on adjacent levels, driving calcification of the ligament. We present a case of marked progression of OPLL at levels adjacent to a previous anterior cervical discectomy and fusion. CASE REPORT A 59-year-old man initially presented for progressive loss of balance and dexterity and underwent a C4-6 anterior cervical discectomy and fusion procedure. Computed tomography performed 1 year postoperatively showed fusion across C4-6 with no evidence of OPLL at any level. Two years following index surgery, the patient reported right-side arm pain. Computed tomography revealed new minimal OPLL opposite the C3-4 level that was not causing cord compression. A sparing midline bilateral C3-7 laminotomy was performed to correct stenosis seen on magnetic resonance imaging. At 7 years after the index procedure, the patient presented with myelopathic symptoms exceeding symptoms at his index presentation. Computed tomography revealed marked progression of OPLL. The patient underwent C2-T2 posterior fusion with laminectomy from C2-C7 and responded well with gradual improvements in balance and arm pain after surgery. CONCLUSIONS Our report demonstrates that OPLL progression, which is largely reported following laminoplasty, may similarly occur following anterior cervical discectomy and fusion and supports the concept of motion-related OPLL progression.

Surgical Trend Analysis for Use of Cement Augmented Pedicle Screws in Osteoporosis of Spine: A Systematic Review (2000-2017)

Study Design: Systematic review. Objectives: (1) Study indications for cement-augmented pedicle screws (CAPS) in patients with osteoporosis. Have they changed over the years (2000-2017)? Are there any differences in usage of CAPS based on the geographical region? (2) What were the outcome of the studies? (3) What are the complications associated with this technique? Methods: Electronic database and reference list of desired articles were searched from the database (2000-2017). Articles were selected discussing indications, clinical and radiological outcomes, and complications in cases of preexistent osteoporosis treated surgically using CAPS. Results: Seventeen studies were identified; 3 were comparative studies and had a control arm (cemented vs noncemented screws). Most studies originated from Europe (10) or Asia (7). Painful vertebral fracture with or without neurological deficit, Kummell’s lesion, deformity and failure to respond to conservative treatment are the common indications for cement augmentation. Visual analogue scale score was the most commonly used to assess pain and average improvement after surgery was 6.1. Average improvement in kyphosis was 13.21° and average loss of correction at the end of the study was 3°. Cement leak was the most common complication observed and pulmonary cement embolism was the most dreaded complication. Nevertheless, majority of cement leaks discussed in studies were asymptomatic. Conclusion: CAPS are being increasingly used in osteoporotic spine. Pain scores, functional quality of life, and neurological function indices were studied. CAPS improved anchorage in osteoporotic vertebra and helped improve/maintain clinical and radiological improvement. Common risks of cement leak were observed.

Self-Made, Cost-Reducing Hemostatic Agent for Use in Spine Surgery

Operative bleeding complications can lead to patient morbidity and mortality as well as longer and increased hospitalization costs. Matrix hemostatic sealants are used commonly to shorten the time to hemostasis, operative times, and the need for blood transfusion. Commercially available hemostatic powders are used in spine surgery because of their ability to conform to wounds and decrease bleeding in difficult-to-access surgical sites. Hospital costs for these agents are variable and are dependent on negotiated institutional contracted prices. We present our technique for mixing and use of our own hemostatic agent that has been used by our senior spine surgeons for more than a decade. It uses supplies that are commonly found in the hospital for a fraction of the cost and at different concentrations of thrombin. We hope that this report serves to assist surgeons working in hospitals with limited resources and enriches their armamentarium of hemostatic agents.