✓ Pedicle screw (PS) instrumentation provides an exceptionally rigid construct to promote fusion in cases of spinal trauma and degenerative disease. Although the safety of traditional open techniques for PS placement has been well documented, there are no large series in the literature in which the safety of percutaneously placed PSs has been examined. Because the advantages of minimally invasive spine surgery are becoming more widely recognized, especially in regard to the lessening of morbidity caused by pain and blood loss, there will be a greater demand for spine surgeons to place PSs percutaneously. During a 2-year period, the authors placed 287 PSs percutaneously with the aid of intraoperative fluoroscopy. Only one of these screws was later found to have breached the spinal canal, yielding a breach rate of 0.35% for percutaneously placed PSs (one of 287).
Ciaran J. Powers, Vinod K. Podichetty, and Robert E. Isaacs
Robert E. Isaacs, Vinod Podichetty, and Richard G. Fessler
The use of microendoscopic discectomy (MED) for the treatment of primary lumbar disc herniations has become fairly well accepted; its role in recurrent disc herniations is less clear. The reluctance of many surgeons to use this technique stems, in part, from the concern of undertaking an endoscopic discectomy in a patient in whom the anatomy is distorted from a previous operation. It appears counterintuitive to operate through a limited working area when the traditional open approach for recurrence favors wider exposure of the surgical field. Given that operating on previously exposed tissue can be associated with even greater morbidity than on virginal tissue, the authors describe their experience with performing MED for recurrent disc herniation.
Unilateral MED was performed in patients with classic symptoms of lumbar radiculopathy, a previous operation at that level, and findings of recurrent disc herniation on magnetic resonance imaging. The approach was similar to a standard MED. Aided by fluoroscopic guidance, a working cannula was docked on the laminofacet junction at the level of the nerve root, with care taken to ensure a slightly more lateral initial trajectory. A good decompression of the nerve root could then be achieved through the use of the endoscope with preservation of the paraspinous musculature and much of the remaining facet capsule.
Ten consecutive patients undergoing the procedure were analyzed prospectively and compared with the previous 25 who underwent routine single-level MED. Use of the MED technique provided excellent visualization and decompression of the nerve root; no conversions to open procedures were necessary in either group. The average operative time in the experimental group was 98.5 minutes, with a mean blood loss of 33 ml and an approximate hospital stay of 7.3 hours. In this respect, there was no statistical difference between the two groups (analysis of variance, p = 0.39, 0.68, and 0.51, respectively). There was one cerebrospinal fluid leak in each group.
Microendoscopic discectomy for recurrent disc herniation can be safely performed without an increase in surgery related morbidity.
Daniel J. Blizzard, Michael A. Gallizzi, Robert E. Isaacs, and Christopher R. Brown
Lateral interbody fusion (LIF) via the retroperitoneal transpsoas approach is an increasingly popular, minimally invasive technique for interbody fusion in the thoracolumbar spine that avoids many of the complications of traditional anterior and transforaminal approaches. Renal vascular injury has been cited as a potential risk in LIF, but little has been documented in the literature regarding the etiology of this injury. The authors discuss a case of an intraoperative complication of renal artery injury during LIF. A 42-year-old woman underwent staged T12–L5 LIF in the left lateral decubitus position, and L5–S1 anterior lumbar interbody fusion, followed 3 days later by T12–S1 posterior instrumentation for idiopathic scoliosis with radiculopathy refractory to conservative management. After placement of the T12–L1 cage, the retractor was released and significant bleeding was encountered during its removal. Immediate consultation with the vascular team was obtained, and hemostasis was achieved with vascular clips. The patient was stabilized, and the remainder of the procedure was performed without complication. On postoperative CT imaging, the patient was found to have a supernumerary left renal artery with complete occlusion of the superior left renal artery, causing infarction of approximately 75% of the kidney. There was no increase in creatinine level immediately postoperatively or at the 3-month follow-up. Renal visceral and vascular injuries are known risks with LIF, with potentially devastating consequences. The retroperitoneal transpsoas approach for LIF in the superior lumbar spine requires a thorough knowledge of renal visceral and vascular anatomy. Supernumerary renal arteries occur in 25%–40% of the population and occur most frequently on the left and superior to the usual renal artery trunk. These arteries can vary in number, position, and course from the aorta and position relative to the usual renal artery trunk. Understanding of renal anatomy and the potential variability of the renal vasculature is essential to prevent iatrogenic injury.
Joshua M. Beckman, Berney Vincent, Michael S. Park, James B. Billys, Robert E. Isaacs, Luiz Pimenta, and Juan S. Uribe
Minimally invasive lateral lumbar interbody fusion (LLIF) via the retroperitoneal transpsoas approach is a technically demanding procedure with a multitude of potential complications. A relatively unknown complication is the contralateral psoas hematoma. The authors speculate that injury occurs from segmental vessel injury at the time of contralateral annulus release; however, this is not fully understood. In this multicenter retrospective review, the authors report the incidence of this contralateral complication and its neurological sequelae.
This study was a retrospective chart review of all minimally invasive LLIF performed at participating institutions from 2008 to 2014. Exclusion criteria included an underlying diagnosis of trauma or neoplasia as well as lateral corpectomies or anterior column releases. Single-level, multilevel, and stand-alone constructs were included. All patients underwent preoperative MRI. Follow-up was at least 12 months. All complications and clinical outcomes were self-reported by each surgeon.
There were 3950 lumbar interbody cages placed via the retroperitoneal transpsoas approach, with 7 cases (0.18% incidence) of symptomatic contralateral psoas hematoma, 3 of which required reoperation for hematoma evacuation. Neurological outcome did not improve after reoperation. Reoperation occurred an average of 1 month after the initial operation due to a delay in diagnosis. In 1 case, segmental artery injury was confirmed at the time of surgery; in the others, segmental vessel injury was suspected, although it could not be confirmed. Neurological deficits persisted in 3 patients while the others remained neurologically intact. Two patients were receiving antiplatelet therapy prior to the procedure.
The contralateral psoas hematoma is a rare complication suspected to occur from segmental vessel injury during contralateral annulus release. Detailed review of preoperative imaging for aberrant vessel anatomy may prevent injury and subsequent neurological deficit.
Timothy Y. Wang, Vikram A. Mehta, Eric W. Sankey, Khoi D. Than, C. Rory Goodwin, Isaac O. Karikari, Robert E. Isaacs, and Muhammad M. Abd-El-Barr
The rate of symptomatic adjacent-segment disease (ASD) after newer minimally invasive techniques, such as lateral lumbar interbody fusion (LLIF), is not known. This study aimed to assess the incidence of surgically significant ASD in adult patients who have undergone index LLIF and to identify any predictive factors.
Patients who underwent index LLIF with or without additional posterior pedicle screw fixation between 2010 and 2012 and received a minimum of 2 years of postoperative follow-up were retrospectively included. Demographic and perioperative data were recorded, as well as radiographic data and immediate perioperative complications. The primary endpoint was revision surgery at the level above or below the previous construct, from which a survivorship model of patients with surgically significant symptomatic ASD was created.
Sixty-seven patients with a total of 163 interbody levels were included in this analysis. In total, 17 (25.4%) patients developed surgically significant ASD and required additional surgery, with a mean ± SD time to revision of 3.59 ± 2.55 years. The mean annual rate of surgically significant ASD was 3.49% over 7.27 years, which was the average follow-up. One-third of patients developed significant disease within 2 years of index surgery, and 1 patient required surgery at the adjacent level within 1 year. Constructs spanning 3 or fewer interbody levels were significantly associated with increased risk of surgically significant ASD; however, instrument termination at the thoracolumbar junction did not increase this risk. Surgically significant ASD was not impacted by preoperative disc height, foraminal area at the adjacent levels, or changes in global or segmental lumbar lordosis.
The risk of surgically significant ASD after LLIF was similar to the previously reported rates of other minimally invasive spine procedures. Patients with shorter constructs had higher rates of subsequent ASD.
Mohammed F. Shamji, Chad Cook, Sean Tackett, Christopher Brown, and Robert E. Isaacs
Cervical spine fusion is performed for various indications in patient populations ranging from young and healthy to aged and frail. Whereas disease pathoanatomy dictates the surgical approach, preoperative neurological status does not necessarily implicate a specific technique. Although one expects anterior decompression to be performed over fewer segments in healthier patients who experience fewer complications and faster recovery, the impact of pre-operative myelopathy on perioperative complications remains unclear. No large-scale study has evaluated rates of common complications for cervical fusion or their association with surgical approach and neurological status.
Data for 96,773 patients who underwent cervical fusion for degenerative disease between 1988 and 2003 were collected from the Nationwide Inpatient Sample database. Patients were grouped according to surgical approach (anterior versus posterior) and preoperative neurological status (myelopathic versus nonmyelopathic). Multivariate regression was used to evaluate group effects on selected postoperative complications, length of stay, and disposition at the time of hospital discharge. Although this technique can control for the observed covariates, the absence of key information such as the number of fused levels precludes statistical comparison between patients who underwent anterior or posterior approaches.
In this study the authors confirmed that preoperative neurological status impacts perioperative morbidity. For example, patients who were nonmyelopathic and underwent an anterior approach were 7 years younger than the rest of the cohort, and they had a mortality rate of 0.05%. Transfusion was required in 0.34%, and venous thromboembolism occurred in 0.04%. Conversely, these rates were > 13-fold higher in patients with myelopathy who underwent a posterior approach. Furthermore, independent of approach, preoperative myelopathy is highly prognostic of death, pneumonia, transfusion, infection, length of stay, and posthospital disposition. These outcomes at least doubled, with some increasing > 10-fold.
This nationwide study clarifies the frequency and associations of inpatient complications encountered when treating cervical spine disease. Whereas immediate complications due to anterior approaches are limited, patients with myelopathy who undergo a posterior approach have a more sobering outlook. This study shows that clinical myelopathy augments rates of complication during cervical fusion, regardless of the approach. The exclusion of pathoanatomical data from the Nationwide Inpatient Sample database, of key importance in guiding the surgical approach, prevents any conclusions being drawn about the merits and disadvantages of anterior versus posterior surgery.
Ankit I. Mehta, Owoicho Adogwa, Isaac O. Karikari, Paul Thompson, Terence Verla, Ulysses T. Null, Allan H. Friedman, Joseph S. Cheng, Carlos A. Bagley, and Robert E. Isaacs
Intradural extramedullary (IDEM) neoplasms are uncommon lesions that can pose a challenge for resection. Numerous factors affect the resectability and ultimately the outcome of these lesions. The authors report their 10-year institutional experience with the resection of IDEM neoplasms, focusing on the effect of location on surgical outcomes.
The authors performed a retrospective review of 96 consecutive patients who presented with a cervical and/or thoracic IDEM tumor that was resected between February 2000 and July 2009. All patients underwent MRI, and the axial location of the tumor was categorized as anterior, posterior, or lateral. Postoperative complications were assessed, as was neurological status at the patient's last follow-up clinic visit. Major complications assessed included CSF leakage requiring lumbar drainage, reexploration for epidural hematoma, and major postoperative neurological deficits.
The mean ± SD age at presentation was 51.16 ± 17.87 years. Major surgical approach–related complications occurred in 15% of patients. Major non–approach related surgical complications occurred in 7.1% of patients, while minor complications occurred in 14.2% of patients. Postoperative neurological deficits occurred most commonly in the thoracic spine between T-1 and T-8. Based on axial spinal cord location, the surgery-related complications rates for all anterior tumors (n = 12) was 41.6%, whereas that for all lateral tumors (n = 69) was 4.4% and that for all posteriorly located tumors (n = 17) was 0%.
Spinal IDEM tumors that are anteriorly located in the upper thoracic spine were found to have the highest rate of surgery-related complications and postoperative neurological deficits. This finding may be associated with the unforgiving anatomy of the upper thoracic spine in which there is a higher cord-to-canal ratio and a tenuous vascular supply.
Owoicho Adogwa, Isaac O. Karikari, Kevin R. Carr, Max Krucoff, Divya Ajay, Parastou Fatemi, Edgar L. Perez, Joseph S. Cheng, Carlos A. Bagley, and Robert E. Isaacs
A spinal epidural abscess (SEA) is a rare but severe infection requiring prompt recognition and management. The incidence of SEA has doubled in the past decade, owing to an aging population and to increased use of spinal instrumentation and vascular access. The optimal management of SEAs in patients 50 years of age and older remains a matter of considerable debate. In an older patient population with multiple comorbidities, whether intravenous antibiotics alone or in combination with surgery lead to superior outcomes remains unknown. The present study retrospectively analyzes cases of SEAs, in patients 50 years of age and older, treated at Duke University Medical Center over the past 15 years.
Eighty-two patients underwent treatment for a spinal epidural abscess between 1999 and 2013. There were 46 men and 36 women, whose overall mean age (± SD) was 65 ± 8.58 years (range 50–82 years). The mean duration of clinical follow-up was 41.38 ± 86.48 weeks. Thirty patients (37%) underwent surgery for removal of the abscess, whereas 52 (63%) were treated more conservatively, undergoing CT-guided aspiration or receiving antibiotics alone based on the results of blood cultures. The correlation between pretreatment variables and outcomes was evaluated in a multivariate regression analysis.
Back pain and severe motor deficits were the most common presenting symptoms. Compared with baseline neurological status, the majority of patients (68%) reported being neurologically “better” or “unchanged.” Twelve patients (15%) had a good outcome (7 [23%] treated operatively vs 5 [10%] treated nonoperatively, p = 0.03), while clinical status in 41 patients (50%) remained unchanged (10 [33%] treated operatively vs 31 [60%] treated nonoperatively, p = 0.01). Overall, 20 patients (25%) died (9 [30%] treated operatively vs 11 [21%] treated nonoperatively, p = 0.43). In a multivariate logistic regression model, an increasing baseline level of pain, the presence of paraplegia or quadriplegia on initial presentation, and a dorsally located SEA were independently associated with poor outcomes.
The results of the study suggest that in patients 50 years of age and older, early surgical decompression combined with intravenous antimicrobial therapy was not associated with superior clinical outcomes when compared with intravenous antimicrobial therapy alone.
Owoicho Adogwa, Ryan Owens, Isaac Karikari, Vijay Agarwal, Oren N. Gottfried, Carlos A. Bagley, Robert E. Isaacs, and Joseph S. Cheng
Despite advances in technology and understanding in spinal physiology, reoperation for symptomatic adjacent-segment disease (ASD), same-level recurrent stenosis, and pseudarthrosis in elderly patients continues to occur. While revision lumbar surgery is effective, attention has turned to questions on the utility and value of the revision decompression and fusion procedure. To date, an analysis of the cost and health state gain associated with revision lumbar surgery in elderly patients with symptomatic pseudarthrosis, ASD, or same-level recurrent lumbar stenosis has yet to be performed. The aim of this study was to assess the long-term outcomes and cost-effectiveness of revision surgery in elderly patients with recurrent or persistent back and leg pain.
After reviewing their institutional database, the authors found 69 patients 65 years of age and older who had undergone revision decompression and instrumented fusion for back and leg pain associated with pseudarthrosis (17 patients), same-level recurrent stenosis (24 patients), or ASD (28 patients) and included them in this study. Total 2-year back-related medical resource utilization and health state values (quality-adjusted life years [QALYs], calculated from the EQ-5D, the EuroQol-5D health survey, with US valuation) were assessed. Two-year resource use was multiplied by unit costs based on Medicare national allowable payment amounts. The mean total 2-year cost per QALY gained after revision surgery was assessed.
The mean (± standard deviation) time between the index surgery and revision surgery was 3.51 ± 3.63 years. A mean cumulative 2-year gain of 0.35 QALY was observed after revision surgery. The mean total 2-year cost of revision surgery was $28,256 ± $3000 (ASD: $28,829 ± $3812, pseudarthrosis: $28,069 ± $2508, same-level recurrent stenosis: $27,871 ± $2375). Revision decompression and extension of fusion was associated with a mean 2-year cost of $80,594 per QALY gained.
Revision decompression and fusion provided a significant gain in health state utility for elderly patients with symptomatic pseudarthrosis, same-level recurrent stenosis, or ASD, with a mean 2-year cost of $80,594 per QALY gained. When indicated, revision surgery for symptomatic ASD, same-level recurrent stenosis, and pseudarthrosis is a valuable treatment option for elderly patients experiencing persistent back and leg pain. Findings in this study provided a value measure of surgery that can be compared with future cost-per-QALY-gained studies of medical management or alternative surgical approaches.
Robert E. Isaacs, Vinod K. Podichetty, Paul Santiago, Faheem A. Sandhu, John Spears, Kevin Kelly, Laurie Rice, and Richard G. Fessler
The authors have developed a novel technique for percutaneous fusion in which standard microendoscopic discectomy is modified. Based on data obtained in their cadaveric studies they considered that this minimally invasive interbody fusion could be safely implemented clinically. The authors describe their initial experience with a microendoscopic transforaminal lumbar interbody fusion (METLIF) technique, with regard to safety in the placement of percutaneous instrumentation, perioperative morbidity, and early postoperative results.
The METLIF procedure was performed unilaterally in 20 patients with single-level lumbar spondylolisthesis or pure mechanical back pain with endoscopic assistance, hemilaminectomy, unilateral facetectomy, and microdiscectomy. Two interbody grafts were placed via the lateral exposure of the disc space. Bilateral percutaneous pedicle screws were then inserted.
Compared with patients who had undergone single-level posterior LIF at the same institutions, intraoperative blood loss, hospital length of stay (LOS), and postoperative narcotic agent use were significantly lower in the METLIF group. The mean LOS for the percutaneous fusion group was 3.4 days (5.1 days in those who underwent PLIF; p < 0.02). There have been no procedure-related complications in this series to date.
The METLIF technique provided an option for percutaneous interbody fusion similar to that in open surgery while minimizing destruction to adjacent tissues. This technique was safe and exhibited a trend toward decreased intraoperative blood loss, postoperative pain, total narcotic use, and the risk of transfusion.