Three- and 4-Level Lumbar Arthrodesis Using Adjunctive Pulsed Electromagnetic Field Stimulation: A Multicenter Retrospective Evaluation of Fusion Rates and a Review of the Literature.

BACKGROUND: The incidence of 3- and 4-level lumbar arthrodesis is rising due to an aging population, and fusion rates affect clinical success in this population. Pulsed electromagnetic field (PEMF) stimulation is used as an adjunct to increase fusion rates following multilevel arthrodesis. The purpose of the study was to evaluate the fusion rates for subjects who underwent 3- and 4-level lumbar interbody arthrodesis following PEMF treatment. METHODS: In this retrospective, multicenter study, patient charts that listed 3- or 4-level lumbar arthrodesis with adjunctive use of a PEMF device were evaluated. Inclusion criteria included patients who were diagnosed with lumbar degenerative disease, spinal stenosis, and/or spondylolisthesis (grade 1 or 2). A radiographic evaluation of fusion status was performed at 12 months by the treating physicians. Fusion rates were stratified by graft material, surgical interbody approach, and certain clinical risk factors for pseudoarthrosis. RESULTS: A total of 55 patients were identified who had a 12-month follow-up. The radiographic fusion rate was 92.7% (51 patients) at 12 months. There were no significant differences in fusion rates for patients treated with allograft or autograft, for patients with different interbody approaches, or for those with or without certain clinical risk factors. CONCLUSIONS: With modern fusion techniques and PEMF, the overall fusion rate was high following 3- and 4-level lumbar arthrodesis. LEVEL OF EVIDENCE: 4. CLINICAL RELEVANCE: PEMF may be a useful adjunct for treatment of patients with surgical risk factors, such as multilevel arthrodesis, and clinical risk factors.

Minimally invasive lateral transiliac sacroiliac joint fusion using 3D-printed triangular titanium implants.

Background: Minimally invasive sacroiliac joint (SIJ) fusion (SIJF) has become an increasingly accepted surgical option for chronic SI joint dysfunction, a prevalent cause of chronic low back/buttock pain. Objective: To report clinical and functional outcomes of SIJF using 3D-printed triangular titanium implants (TTI) for patients with chronic SI joint dysfunction. Methods: A total of 28 subjects with SIJ dysfunction at 8 centers underwent SIJF with 3D TTI and had scheduled follow-up to 6 months (NCT03122899). Results: Mean preoperative SIJ pain score was 79.1 and mean preoperative Oswestry Disability Index (ODI) was 49.9. At 6 months, pain scores decreased by 51 points and ODI decreased by 23.6 points (both p<0.0001). The proportion of subjects able to perform various back/pelvis-related physical functions with minimal difficulty improved significantly for nearly all activities. Opioid use decreased and physical function, as assessed with three objective tests, improved. Conclusion: Early results from this prospective multicenter trial confirm that clinical responses to a 3D triangular titanium implant for SIJF are similar to those from prior trials, with improved physical function and decreased opioid use. Level of evidence: Level II.

Technical description of oblique lateral interbody fusion at L1-L5 (OLIF25) and at L5-S1 (OLIF51) and evaluation of complication and fusion rates.

BACKGROUND CONTEXT: The oblique lateral interbody fusion (OLIF) procedure is aimed at mitigating some of the challenges seen with traditional anterior lumbar interbody fusion (ALIF) and transpsoas lateral lumbar interbody fusion (LLIF), and allows for interbody fusion at L1-S1. PURPOSE: The study aimed to describe the OLIF technique and assess the complication and fusion rates. STUDY DESIGN: This is a retrospective cohort study. PATIENT SAMPLE: The sample is composed of 137 patients who underwent OLIF procedure. OUTCOME MEASURES: The outcome measures were adverse events within 6 months of surgery: infection, symptomatic pseudarthrosis, hardware failure, vascular injury, perioperative blood transfusion, ureteral injury, bowel injury, renal injury, prolonged postoperative ileus (more than 3 days), incisional hernia, pseudohernia, reoperation, neurologic deficits (weakness, numbness, paresthesia), hip flexion pain, retrograde ejaculation, sympathectomy affecting lower extremities, deep vein thrombosis, pulmonary embolism, myocardial infarction, pneumonia, and cerebrovascular accident. The outcome measures also include fusion and subsidence rates based on computed tomography (CT) done at 6 months postoperatively. METHODS: Retrospective chart review of 150 consecutive patients was performed to examine the complications associated with OLIF at L1-L5 (OLIF25), OLIF at L5-S1 (OLIF51), and OLIF at L1-L5 combined with OLIF at L5-S1 (OLIF25+OLIF51). Only patients who had at least 6 months of postoperative follow-up, including CT scan at 6 months after surgery, were included. Independent radiology review of CT data was performed to assess fusion and subsidence rates at 6 months. RESULTS: A total of 137 patients underwent fusion at 340 levels. An overall complication rate of 11.7% was seen. The most common complications were subsidence (4.4%), postoperative ileus (2.9%), and vascular injury (2.9%). Ileus and vascular injuries were only seen in cases including OLIF51. No patient suffered neurologic injury. No cases of ureteral injury, sympathectomy affecting the lower extremities, or visceral injury were seen. Successful fusion was seen at 97.9% of surgical levels. CONCLUSIONS: Oblique lateral interbody fusion is a safe procedure at L1-L5 as well as L5-S1. The complication profile appears acceptable when compared with LLIF and ALIF. The oblique trajectory mitigates psoas muscle and lumbosacral plexus-related complications seen with the lateral transpsoas approach. Furthermore, there is a high fusion rate based on CT data at 6 months.

Contralateral psoas hematoma after minimally invasive, lateral retroperitoneal transpsoas lumbar interbody fusion: a multicenter review of 3950 lumbar levels.

OBJECTIVE 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.

Lumbar Total Disc Replacement for Discogenic Low Back Pain: Two-year Outcomes of the activL Multicenter Randomized Controlled IDE Clinical Trial.

STUDY DESIGN: A prospective, multicenter, randomized, controlled, investigational device exemption (IDE) noninferiority trial. OBJECTIVE: The aim of this study was to evaluate the comparative safety and effectiveness of lumbar total disc replacement (TDR) in the treatment of patients with symptomatic degenerative disc disease (DDD) who are unresponsive to nonsurgical therapy. SUMMARY OF BACKGROUND DATA: Lumbar TDR has been used to alleviate discogenic pain and dysfunction while preserving segmental range of motion and restoring stability. There is a paucity of data available regarding the comparative performance of lumbar TDR. METHODS: Patients presenting with symptomatic single-level lumbar DDD who failed at least 6 months of nonsurgical management were randomly allocated (2:1) to treatment with an investigational TDR device (activL, n = 218) or FDA-approved control TDR devices (ProDisc-L or Charité, n = 106). The hypothesis of this study was that a composite effectiveness outcome at 2 years in patients treated with activL would be noninferior (15% delta) to that in controls. RESULTS: The primary composite endpoint of this study was met, which demonstrated that the activL TDR was noninferior to control TDR (P < 0.001). A protocol-defined analysis of the primary composite endpoint also confirmed that activL was superior to controls (P = 0.02). Radiographic success was higher with activL versus controls (59% vs. 43%; P < 0.01). Mean back pain severity improved by 74% with activL and 68% with controls. Oswestry Disability Index scores decreased by 67% and 61% with activL and controls, respectively. Patient satisfaction with treatment was over 90% in both groups at 2 years. Return to work was approximately 1 month shorter (P = 0.08) with activL versus controls. The rate of device-related serious adverse events was lower in patients treated with activL versus controls (12% vs. 19%; P = 0.13). Surgical reintervention rates at the index level were comparable (activL 2.3%, control 1.9%). CONCLUSION: The single-level activL TDR is safe and effective for the treatment of symptomatic lumbar DDD through 2 years. LEVEL OF EVIDENCE: 2.

Comparison of Intervertebral ROM in Multi-Level Cadaveric Lumbar Spines Using Distinct Pure Moment Loading Approaches.

BACKGROUND: Pure-moment loading is the test method of choice for spinal implant evaluation. However, the apparatuses and boundary conditions employed by laboratories in performing spine flexibility testing vary. The purpose of this study was to quantify the differences, if they exist, in intervertebral range of motion (ROM) resulting from different pure-moment loading apparatuses used in two laboratories. METHODS: Twenty-four (laboratory A) and forty-two (laboratory B) intact L1-S1 specimens were loaded using pure moments (±7.5 Nm) in flexion-extension (FE), lateral bending (LB) and axial torsion (AT). At laboratory A, pure moments were applied using a system of cables, pulleys and suspended weights in 1.5 Nm increments. At laboratory B, specimens were loaded in a pneumatic biaxial test frame mounted with counteracting stepper-motor-driven biaxial gimbals. ROM was obtained in both labs using identical optoelectronic systems and compared. RESULTS: In FE, total L1-L5 ROM was similar, on average, between the two laboratories (lab A: 37.4° ± 9.1°; lab B: 35.0° ± 8.9°, p=0.289). Larger apparent differences, on average, were noted between labs in AT (lab A: 19.4° ± 7.3°; lab B: 15.7° ± 7.1°, p=0.074), and this finding was significant for combined right and left LB (lab A: 45.5° ± 11.4°; lab B: 35.3° ± 8.5°, p < 0.001). CONCLUSIONS: To our knowledge, this is the first study comparing ROM of multi-segment lumbar spines between laboratories utilizing different apparatuses. The results of this study show that intervertebral ROM in multi-segment lumbar spine constructs are markedly similar in FE loading. Differences in boundary conditions are likely the source of small and sometimes statistically significant differences between the two techniques in LB and AT ROM. The relative merits of each testing strategy with regard to the physiologic conditions that are to be simulated should be considered in the design of a study including LB and AT modes of loading. An understanding of these differences also serves as important information when comparing study results across different laboratories.

Early Radiographic and Clinical Outcomes Study Evaluating an Integrated Screw and Interbody Spacer for One- and Two-Level ACDF.

BACKGROUND: Multiple techniques and implants can be used in ACDF, the newest of which are integrated cage and screw constructs. These devices may be beneficial over anterior plate constructs due to a negligible anterior profile that may reduce dysphagia. The goal of this study is to review the early radiographical and clinical results associated with a low profile integrated intervertebral cage in one- and two-level anterior column fusions. METHODS: Fusion rates, incidence of hardware failure and deformity correction were assessed through 1 year. Patientreported scores, including VAS for neck pain, and improvements in axial neck pain and neurologic deficit from the preoperative baseline were quantified at 3, 6 and 12 months post-operatively. The incidence of dysphagia was recorded. RESULTS: Lordosis and disc space height at the operated levels increased an average of 4.5° and 3.3mm after device placement (p<0.001). Sagittal plane correction was maintained at 1 year. VAS improved from an average of 5.1 preoperatively to 3.1 immediately postoperatively and was maintained at 12 months. At 3 months, patient-reported improvements in axial neck pain and neurologic deficit were 85% and 93%, respectively. Reported improvements were sustained for both parameters at 12 months (77% and 86%, respectively). Fusion was noted in 93% of the operated levels. There were two documented cases of dysphagia that lasted more than 5 weeks, both following two level ACDFs with the test device (3.5% rate of chronic dysphagia). CONCLUSIONS: The low profile integrated device improved lordosis at the operated level that was maintained at 1 year. Fusion rates with the new device are consistent with ACDF using anterior plating. In combination with improvements in pain and a minimal rate of dysphagia, study findings support the use of integrated interbody spacers for use in one- and two-level ACDF procedures. LEVEL OF EVIDENCE: Level IV, Case Series.

A cadaveric radiographic analysis on the effect of extreme lateral interbody fusion cage placement with supplementary internal fixation on indirect spine decompression.

STUDY DESIGN: Cadaveric Biomechanical and Radiographic Analysis. OBJECTIVE: The purpose of this study was to quantify the changes in intervertebral height and lateral and central recess areas afforded by lateral interbody fusion cages with 2 supplemental forms of internal fixation in cadaveric specimens. BACKGROUND DATA: When conservative treatment for symptomatic lumbar stenosis fails, traditional intervention has been direct posterior decompression. The minimally invasive, lateral transpsoas approach may be a viable alternative to direct decompression by providing restoration of the foraminal and intervertebral dimensions, yet few reports have examined the anatomic and radiographic changes that occur using this technique. METHODS: Computed tomography (CT) scans were taken of 18 intact lumbar (L1-S1) cadaveric specimens under a 400 N preload. Intervertebral height, foraminal areas, and canal area were measured at L3-L4 and L4-L5. Thereafter, the cadaveric specimens were instrumented with lateral cages placed in the central or posterior third of the disk space at L3-L4 and L4-L5 and either (1) lateral plate (n=9) or (2) bilateral posterior pedicle screw fixation (n=9). All constructs were again subjected to a 400 N preload, postinstrumentation CT scans were taken, and changes in intervertebral height and lateral and central recess areas were calculated. RESULTS: There was no effect of cage placement on any radiographic metric of indirect decompression for either fusion construct. In the lateral plate and pedicle screw groups, respectively, significant increases in average posterior disk height (30.9%, 60.1%), average right (35.3%, 61.5%) and left foraminal area (48.3%, 57.8%), and average canal area (32.3%, 33.3%) were observed. Pedicle screw instrumentation afforded a significantly greater increase in average posterior disk height and foraminal area compared with the lateral plate group, though there was no difference in the average increase in canal area afforded by either form of fixation. CONCLUSIONS: The radiographic results reported here using a cadaveric model add validity to the underlying rationale described for the minimally invasive lateral approach technique. Increases in disk height, foraminal and canal areas were not dependent on cage positioning within the disk space. As intraoperative placement of a cage in the central portion of the disk is an easier and safer technique, our results suggest that central placement may be preferable in a clinical setting.

Biomechanics of lateral plate and pedicle screw constructs in lumbar spines instrumented at two levels with laterally placed interbody cages.

BACKGROUND CONTEXT: The lateral transpsoas approach to interbody fusion is gaining popularity because of its minimally invasive nature and resultant indirect neurologic decompression. The acute biomechanical stability of the lateral approach to interbody fusion is dependent on the type of supplemental internal fixation used. The two-hole lateral plate (LP) has been approved for clinical use for added stabilization after cage instrumentation. However, little biomechanical data exist comparing LP fixation with bilateral pedicle screw and rod (PSR) fixation. PURPOSE: To biomechanically compare the acute stabilizing effects of the two-hole LP and bilateral PSR fusion constructs in lumbar spines instrumented with a lateral cage at two contiguous levels. STUDY DESIGN: Biomechanical laboratory study of human cadaveric lumbar spines. METHODS: Eighteen L1-S1 cadaveric lumbar spines were instrumented with lateral cages at L3-L4 and L4-L5 after intact kinematic analysis. Specimens (n=9 each) were allocated for supplemental instrumentation with either LP or PSR. Intact versus instrumented range of motion was evaluated for all specimens by applying pure moments (±7.5 Nm) in flexion/extension, lateral bending (LB) (left+right), and axial rotation (AR) (left+right). Instrumented spines were later subjected to 500 cycles of loading in all three planes, and interbody cage translations were quantified using a nonradiographic technique. RESULTS: Lateral plate fixation significantly reduced ROM (p<.05) at both lumbar levels (flexion/extension: 49.5%; LB: 67.3%; AR: 48.2%) relative to the intact condition. Pedicle screw and rod fixation afforded the greatest ROM reductions (p<.05) relative to the intact condition (flexion/extension: 85.6%; LB: 91.4%; AR: 61.1%). On average, the largest interbody cage translations were measured in both fixation groups in the anterior-posterior direction during cyclic AR. CONCLUSIONS: Based on these biomechanical findings, PSR fixation maximizes stability after lateral interbody cage placement. The nonradiographic technique served to quantify migration of implanted hardware and may be implemented as an effective laboratory tool for surgeons and engineers to better understand mechanical behavior of spinal implants.

Hybrid dynamic stabilization with posterior spinal fusion in the lumbar spine.

BACKGROUND: Instrumented lumbar arthrodesis has been established as the gold standard in the care of patients with degenerative disc disease. However, spinal fusion results in the elimination of motion of the functional spinal unit and has been implicated in the development of adjacent-level degeneration. Motion-preserving devices such as the dynamic rod allow for stabilization of a pathologic motion segment above a fused segment and create a transitional zone (index level) that decreases the loads applied to the supra-adjacent normal segment. METHODS: After institutional review board approval, 28 patients were included in this prospective, consecutive, nonrandomized clinical trial. Each subject was consented for dynamic stabilization. There was no attempt at fusion at the dynamic level. The cohort underwent a posterior lateral spinal fusion with single- or 2-level transforaminal lumbar interbody fusion by use of a cage, with superior-level posterior dynamic instrumentation. Functional clinical outcomes were measured with a 100-point visual analog scale, Oswestry Disability Index, and Short Form 36 questionnaire. Radiographic measurements, fusion evaluation, complications, and screw loosening were recorded. RESULTS: A minimum of 24 months' follow-up data included 22 patients. No device failure or screw breakage was identified. Postoperative range of motion averaged 2.5° at the index level, and the superior adjacent-level range of motion remained unchanged (P > .05). Disc height was preserved at all levels (P > .05). Of 180 screws, 6 (3%) showed radiographic loosening. Functional outcomes showed significant improvement in mean postoperative visual analog scale score by 24.7 points (P < .01) and Oswestry Disability Index by 27.6 points (P < .01), as well as the Short Form 36 physical (P < .01) and mental (P < .05) components from baseline to 2-year follow-up. CONCLUSIONS: Our preliminary results at 2 years are satisfactory. CLINICAL RELEVANCE: Ultimately, further follow-up will assess the potential for this treatment to delay adjacent-level changes in the long term.