Analysis of single-position for revision surgery using lateral interbody fusion and pedicle screw fixation: feasibility and perioperative results.

BACKGROUND: To analyze perioperative and radiographic outcomes following revision surgery using lateral lumbar interbody fusion (LLIF) performed entirely in the lateral position. Traditionally, patients undergoing interbody fusion in the lateral decubitus position are placed prone for pedicle screw fixation. However prone positioning carries known risks and may increase surgical time due to the need to re-drape and reposition. Little is published regarding revision surgery in a single position. METHODS: Sixteen patients over the age of 18 with degenerative lumbar pathology who underwent a revision of previous lumbar fusion using interbody fusion via lateral access and revision of posterior instrumentation from a single surgeon met inclusion criteria. Patients who underwent combined procedures requiring repositioning or had inadequate preoperative imaging were excluded. Patients remained in the lateral decubitus position for the entirety of the procedure including interbody placement, revision of prior instrumentation, and pedicle screw fixation. Demographics, surgical details, and perioperative outcomes were reported. RESULTS: The mean operative time was 211 minutes for all cases, 161 minutes for single-level procedures and 296 minutes for two-level procedures. Mean estimated blood loss was 206 cc. The mean patient age was 66, 70% of which were male. The mean body mass index (BMI) was 27.4 and Charleson Comorbidity Index (CCI) was 3. All cases were performed on the lumbar spine (T12/L1-L4/L5), with the majority of procedures performed at the L2/3 level (44%). The mean pelvic incidence (PI) was 60 degrees (range, 41-71 degrees) with mean preoperative PI/lumbar lordosis (LL) mismatch of 23.9 degrees. Mean postoperative PI/LL mismatch was 12 degrees. CONCLUSIONS: Revision surgery in the lateral position is feasible with complication rates comparable to published literature. The need to reposition is eliminated and single position surgery reduces operative time.

Short-Term Outcomes of Staged Versus Same-Day Surgery for Adult Spinal Deformity Correction.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Assess differences between staged (≤3 days) and same-day surgery in perioperative factors, radiographic measures, and complications. SUMMARY OF BACKGROUND DATA: Surgical adult spinal deformity correction may require combined anterior and posterior approaches. To modulate risk, some surgeons perform surgery that is expected to be longer and/or more complex in two stages. Prior studies comparing staged (≥7 days) and same-day surgery demonstrated mixed results and none have examined results with shorter staging intervals. METHODS: Retrospective review of adults undergoing combined anterior/posterior approaches for spinal deformity over a 3-year period at a single institution (n=92). Univariate differences between staged and same-day surgery were assessed with chi-squared, Fisher exact, and Mann-Whitney U tests. Generalized estimating equations assessed whether differences in perioperative outcomes between groups remained after adjusting for differences in demographic and surgical characteristics. RESULTS: In univariate analyses, staged surgery was associated with a length of stay (LOS) 3 days longer than same-day surgery (9.2 vs. 6.3 days, p < .001), and greater operative time, blood loss, transfusion requirement, and days in intensive care unit (p < .001 for each). Staged surgery had a higher rate of thrombotic events (p = .011) but did not differ in readmission rates or other complications. Radiographically, improvements in Cobb angle (average 13° vs. 17°, p = .028), lumbar lordosis (average 14° vs. 23°, p = .019), and PI-LL mismatch (average 10° vs. 2° p = .018) were greater for staged surgery, likely related to more extensive use of osteotomies in the staged group. After risk adjustment, taking into account the procedural specifics including longer fusion constructs and greater number of osteotomies, LOS no longer differed between staged and same-day surgery; however, the total operative time was 98 minutes longer for staged surgery (p < .001). Differences in blood loss between groups was accounted for by differences in operative time and patient and surgical characteristics. CONCLUSIONS: Although univariate analysis of our results were in accordance with previously published works, multivariate analysis allowing individual case risk adjustment revealed that LOS was not significantly increased in the staged group as reported in previous studies. There was no difference in infection rates as previously described but an increase in thrombotic events was observed. LEVEL OF EVIDENCE: Level III.

Computer-assisted surgical navigation is associated with an increased risk of neurological complications: a review of 67,264 posterolateral lumbar fusion cases.

BACKGROUND: Pedicle screw malposition may result in neurological complications following posterolateral lumbar fusions (PLF). While computer-assisted navigation (NAV) and intraoperative neuromonitoring (ION) have been shown to improve safety in deformity surgeries, their use in routine PLFs remain controversial. This study assesses the risk of complications and reoperation for pedicle screw revision following PLF with and without ION and/or NAV surgery. METHODS: Retrospective analyses were performed using the Truven Health MarketScan® databases to identify patients that had primary PLF with and without NAV and/or ION for degenerative lumbar disorders from years 2007-2015. Patients undergoing concomitant interbody fusions, spinal deformity surgery or fusion to the thoracic spine were excluded. Complications and reoperation for pedicle screw revision within 90 days of surgery were assessed. RESULTS: During the study period, 67,264 patients underwent PLFs. NAV only was used in 3.5% of patients, ION only in 17.9% and both NAV and ION in 0.8% of patients. In univariate analyses, there was a difference in the risk of neurological injuries among groups (NAV only: 1.4%, ION only: 0.8%, NAV and ION: 0.5%, No NAV or ION: 0.6%, P<0.001). In multivariable models, the use of NAV was associated with a higher risk of neurological complications when compared to ION only or no ION or NAV [NAV vs. ION only: odds ratio (OR) and 95% confidence interval (CI) =2.1 (1.4, 3.2), P=0.002; NAV vs. no ION or NAV: OR and 95% CI =2.5 (1.7, 3.5), P<0.001]. There was no difference in reoperation rates among the groups (P=0.135). CONCLUSIONS: Although the overall risk of neurological complications following PLFs is low, the use of NAV only was associated with an increased risk of neurological complications. No differences were observed in the rates of pedicle screw revision among groups.

Abundant heterotopic bone formation following use of rhBMP-2 in the treatment of acetabular bone defects during revision hip arthroplasty.

Revision hip arthroplasty in the setting of periacetabular bone loss presents a significant challenge, as options for restoring bone loss are limited. Recombinant human bone morphogenetic protein-2 may offer a solution by promoting bone growth to restore bone stock before implant reimplantation. Here we present a case of a patient with a periprosthetic acetabulum fracture, resulting in pelvic discontinuity as the result of significant periacetabular bone loss. Using a staged approach, periacetabular bone stock was nearly entirely reconstituted using recombinant BMPs and allograft, which resulted in stable fixation, but with abundant heterotopic bone formation. Recombinant BMP-2 offers a useful tool for restoring bone stock in complex hip arthroplasty revision cases with periacetabular bone loss; however, caution must be used as overabundant bone growth as heterotopic ossification may result.

Bisphosphonate and Teriparatide Use in Thoracolumbar Spinal Fusion: A Systematic Review and Meta-analysis of Comparative Studies.

STUDY DESIGN: Systematic review and meta-analysis. OBJECTIVE: To compare the efficacy of the use of either bisphosphonates or teriparatide on radiographic and functional outcomes of patients that had thoracolumbar spinal fusion. SUMMARY OF BACKGROUND DATA: Controversy exists as to whether bisphosphonates interfere with successful spinal arthrodesis. An alternative osteoporosis medication is teriparatide, a synthetic parathyroid hormone that has an anabolic effect on osteoblast function. To date, there is limited comparative data on the influence of bisphosphonates or teriparatide on spinal fusion. METHODS: A systematic search of medical reference databases was conducted for comparative studies on bisphosphonate or teriparatide use after thoracolumbar spinal fusion. Meta-analysis was performed using the random-effects model for heterogeneity. Radiographic outcomes assessed include fusion rates, risk of screw loosening, cage subsidence, and vertebral fracture. RESULTS: No statistically significant differences were noted between bisphosphonates and control groups regarding fusion rate and risk of screw loosening (fusion: odds ratio [OR] = 2.2, 95% confidence interval [CI]: 0.87-5.56, P = 0.09; loosening: OR = 0.45, 95% CI: 0.14-1.48, P = 0.19). Teriparatide use was associated with higher fusion rates than bisphosphonates (OR = 2.3, 95% CI: 1.55-3.42, P < 0.0001). However, no statistically significant difference was noted between teriparatide and bisphosphonates regarding risk of screw loosening (OR = 0.37, 95% CI: 0.12-1.18, P = 0.09). Lastly, bisphosphonate use was associated with decreased odds of cage subsidence and vertebral fractures compared to controls (subsidence: OR = 0.29, 95% CI 0.11-0.75, P = 0.01; fracture: OR = 0.18, 95% CI 0.07-0.48, P = 0.0007). CONCLUSION: Bisphosphonates do not appear to impair successful spinal fusion compared to controls although teriparatide use is associated with higher fusion rates than bisphosphonates. In addition, bisphosphonate use is associated with decreased odds of cage subsidence and vertebral fractures compared to controls that had spinal fusion. LEVEL OF EVIDENCE: 3.

Does Preoperative Pneumonia Affect Complications of Geriatric Hip Fracture Surgery?

Preoperative pneumonia, reported in 0.3% to 3.2% of hip fracture patients, may be a risk factor for adverse outcomes of hip fracture repair. No studies have reported on baseline differences or adverse outcomes in surgically managed geriatric hip fracture patients with and without preoperative pneumonia, and no data argue for or against delaying surgery in these patients. A retrospective cohort of geriatric patients with operatively treated hip fractures from 2005 to 2012 was identified in the National Surgical Quality Improvement Program database. Preoperative pneumonia was present in 82 (1.2%) of 7128 geriatric hip fracture patients identified and was associated with male sex, transfer status, functional status, preoperative anemia, confusion, dyspnea at rest, and chronic obstructive pulmonary disease. Multivariate analysis of 30-day outcomes of hip fracture repair revealed that preoperative pneumonia was associated with a higher risk for any adverse event (relative risk [RR] = 1.44), serious adverse event (RR = 1.79), and death (RR = 2.08) after hip fracture repair. Underweight body mass index at time of surgery (<18.5 kg/m²) was predictive of 30-day mortality (RR = 4.67). Surgical delay of 1 to 4 days was not associated with adverse events. Geriatric hip fracture patients with preoperative pneumonia, especially the underweight, are at increased risk for complications and death after hip fracture repair. We cannot recommend against early hip fracture surgery in this population.

Hinged-Knee External Fixator Used to Reduce and Maintain Subacute Tibiofemoral Coronal Subluxation.

Dislocation of the knee is a rare phenomenon that is becoming increasingly recognized with the expansion of its definition to include knees presenting with multiligament compromise. Hinged external fixators are now considered a viable supplementary treatment option in the management of acute ligament repair or reconstruction but their use in the management of subacute or chronic tibiofemoral dislocations or subluxations is less well defined. We report a case of a hinged-knee external fixator used to facilitate and maintain reduction of a chronic coronal tibial subluxation that presented after repair of an acute knee dislocation with lateral ligament injury secondary to a motor vehicle accident. At 5-year follow-up, the patient treated with hinged external fixation had a stable joint, was able to tolerate regular aerobic exercise, was minimally symptomatic, and did not require more extensive ligament reconstruction. Although there are reports on postoperative use of hinged external fixation to maintain the reduction of chronic or subacute knee dislocations in the sagittal plane after cruciate ligament repair, there are no reports on management of subacute tibiofemoral subluxation in the coronal plane.

Intravitreal delivery of human NgR-Fc decoy protein regenerates axons after optic nerve crush and protects ganglion cells in glaucoma models.

PURPOSE: Glaucoma is a major cause of vision loss due to retinal ganglion cell (RGC) degeneration. Therapeutic intervention controls increased IOP, but neuroprotection is unavailable. NogoReceptor1 (NgR1) limits adult central nervous system (CNS) axonal sprouting and regeneration. We examined NgR1 blocking decoy as a potential therapy by defining the pharmacokinetics of intravitreal NgR(310)-Fc, its promotion of RGC axonal regeneration following nerve crush, and its neuroprotective effect in a microbead glaucoma model. METHODS: Human NgR1(310)-Fc was administered intravitreally, and levels were monitored in rat vitreal humor and retina. Axonal regeneration after optic nerve crush was assessed by cholera toxin ß anterograde labeling. In a microbead model of glaucoma with increased IOP, the number of surviving and actively transporting RGCs was determined after 4 weeks by retrograde tracing with Fluro-Gold (FG) from the superior colliculus. RESULTS: After intravitreal bolus administration, the terminal half-life of NgR1(310)-Fc between 1 and 7 days was approximately 24 hours. Injection of 5 µg protein once per week after optic nerve crush injury significantly increased RGCs with regenerating axons. Microbeads delivered to the anterior chamber increased pressure, and caused 15% reduction in FG-labeled RGCs of control rats, with a 40% reduction in large diameter RGCs. Intravitreal treatment with NgR1(310)-Fc did not reduce IOP, but maintained large diameter RGC density at control levels. CONCLUSIONS: Human NgR1(310)-Fc has favorable pharmacokinetics in the vitreal space and rescues large diameter RGC counts from increased IOP. Thus, the NgR1 blocking decoy protein may have efficacy as a disease-modifying therapy for glaucoma.

Axonal regeneration induced by blockade of glial inhibitors coupled with activation of intrinsic neuronal growth pathways.

Several pharmacological approaches to promote neural repair and recovery after CNS injury have been identified. Blockade of either astrocyte-derived chondroitin sulfate proteoglycans (CSPGs) or oligodendrocyte-derived NogoReceptor (NgR1) ligands reduces extrinsic inhibition of axonal growth, though combined blockade of these distinct pathways has not been tested. The intrinsic growth potential of adult mammalian neurons can be promoted by several pathways, including pre-conditioning injury for dorsal root ganglion (DRG) neurons and macrophage activation for retinal ganglion cells (RGCs). Singly, pharmacological interventions have restricted efficacy without foreign cells, mechanical scaffolds or viral gene therapy. Here, we examined combinations of pharmacological approaches and assessed the degree of axonal regeneration. After mouse optic nerve crush injury, NgR1-/- neurons regenerate RGC axons as extensively as do zymosan-injected, macrophage-activated WT mice. Synergistic enhancement of regeneration is achieved by combining these interventions in zymosan-injected NgR1-/- mice. In rats with a spinal dorsal column crush injury, a preconditioning peripheral sciatic nerve axotomy, or NgR1(310)ecto-Fc decoy protein treatment or ChondroitinaseABC (ChABC) treatment independently support similar degrees of regeneration by ascending primary afferent fibers into the vicinity of the injury site. Treatment with two of these three interventions does not significantly enhance the degree of axonal regeneration. In contrast, triple therapy combining NgR1 decoy, ChABC and preconditioning, allows axons to regenerate millimeters past the spinal cord injury site. The benefit of a pre-conditioning injury is most robust, but a peripheral nerve injury coincident with, or 3 days after, spinal cord injury also synergizes with NgR1 decoy and ChABC. Thus, maximal axonal regeneration and neural repair are achieved by combining independently effective pharmacological approaches.