Midline lumbar interbody fusion: a review of the surgical technique and outcomes.

Midline lumbar interbody fusion (MidLIF) is a mini-open posterior interbody fusion technique defined by a cortical screw trajectory wherein screws are placed from a more medial to lateral trajectory compared with traditional pedicle screws. This enables the surgeon to perform a smaller muscle dissection with the benefits of improved blood loss, less muscle retraction, decreased operative time, shorter length of stay, and improved back pain outcomes compared with the traditional posterior lumbar interbody fusion techniques utilizing pedicle screw fixation. Importantly, MidLIF offers comparable clinical outcomes and radiographic outcomes to other posterior lumbar interbody fusion techniques. In the current review, the authors aimed to educate readers about the MidLIF surgical technique, as well as surgical, clinical, radiographic, cost effectiveness, and biomechanical outcomes, when compared with both open and minimally invasive posterior lumbar interbody fusion techniques with pedicle screw fixation. Readers will be able to utilize this information to determine how the MidLIF procedure compares as an alternative to traditional techniques.

Use of an intraoperative sodium oxychlorosene-based infection prevention protocol to safely decrease postoperative wound infections after spine surgery.

OBJECTIVE: Postoperative infection remains prevalent after spinal surgical procedures. Institutional protocols for infection prevention have improved rates of infection after spine surgery. However, prior studies have focused on only elective surgical patients. The aim of this study was to determine the efficacy of a multiinstitutional intraoperative sodium oxychlorosene-based infection prevention protocol for decreasing rate of infection after instrumented spinal surgery. METHODS: A retrospective analysis was performed at two tertiary care institutions with level I trauma programs, and patients who underwent posterior instrumented spinal fusion between January 1, 2011, and May 31, 2019, were included. Postoperative deep wound infection rates were captured before and after implementation of a multiinstitutional infection prevention protocol. Possible adverse outcomes related to infection prevention techniques were also examined. In addition, consecutive patients treated from January 1, 2018, to May 31, 2019, were prospectively included in a database to collect preoperative and postoperative spine-specific quality of life measures and to assess the impact of postoperative infection on quality of life. RESULTS: A total of 5047 patients fit the inclusion criteria. Of these, 1043 patients underwent surgery prior to protocol implementation. The infection rate of this cohort (3.5%) decreased significantly after protocol implementation (1.2%, p < 0.001). Postoperative sterile seroma rates did not differ between the preprotocol and postprotocol groups (0.7% vs 0.7%, p = 0.5). In the 1031 patients who underwent surgery between January 2018 and May 2019, the fusion rate was 89.2%. Quality of life outcomes between patients with infection and those without infection were similar, although statistical power was limited owing to the low rate of infection. Notably, 2 of 10 patients who developed deep wound infection died of infection-related complications. CONCLUSIONS: An intraoperative sodium oxychlorosene-based infection prevention protocol helped to significantly decrease the rate of infection after spine surgery without negatively impacting other postoperative procedure-related metrics. Postoperative wound infection may be associated with higher-than-expected rate of postoperative mortality.

Safety and efficacy of low-dose rhBMP-2 use for anterior cervical fusion.

OBJECTIVE: The use of recombinant human bone morphogenetic protein 2 (rhBMP-2) in routine anterior cervical fusion (ACF) is controversial. Early reports described high complication rates. A variety of dosing regimens ranging from 0.6 to 2.1 mg per level fused have been reported. The authors hypothesized that the high amounts of rhBMP-2 used in these studies led to the high complication rates observed; therefore, they set out to evaluate the safety and efficacy of low-dose rhBMP-2 for use in ACFs. METHODS: Patient inclusion criteria were 1) age 18 to 70 years; 2) initial stand-alone ACF construct; 3) fusion augmentation with rhBMP-2; and 4) at least 1 year of radiographic follow-up. A successful fusion was defined by either 1) lateral flexion-extension radiographs with less than 1 mm of movement across the fused spinous processes, or 2) bone bridging at least half of the fusion area originally achieved by surgery on fine-cut CT. Patient demographics, perioperative data, and postoperative complications were recorded. RESULTS: A total of 198 patients met the inclusion criteria and were included for analysis. Sixty-two patients (31%) were smokers. The median number of levels fused was 2 (IQR 1.25). The mean dose of rhBMP-2 was 0.50 ± 0.09 mg per level. Twenty-two (11%) patients experienced dysphagia. Eleven (6%) patients experienced cervical swelling. Two (1%) patients returned to the operating room (OR) for postoperative hematoma. One (0.5%) patient returned to the OR for seroma. Two (1%) patients experienced pseudarthrosis requiring a posterior fusion. Three (2%) patients experienced a new postoperative neurological deficit that had recovered by last the follow-up. Overall, 190 (96%) patients experienced solid arthrodesis over an average of 15 months of follow-up. There was no difference in fusion rates between patients who were either smokers or nonsmokers (p = 0.7073). CONCLUSIONS: The use of low-dose rhBMP-2 safely and effectively augmented anterior cervical arthrodesis. The low-dose protocol assessed in this study appeared to significantly reduce complications associated with rhBMP-2 use in ACF compared with the literature. The authors have determined that using low-dose rhBMP-2 in patients who are smokers, those with multilevel ACFs, or others at high risk of developing pseudarthrosis is recommended.

The Use of Bone Morphogenetic Protein in the Intervertebral Disk Space in Minimally Invasive Transforaminal Lumbar Interbody Fusion: 10-year Experience in 688 Patients.

STUDY DESIGN: Retrospective Cohort. OBJECTIVE: The objective of this study was to characterize one surgeon's experience over a 10-year period using rhBMP-2 in the disk space for minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). SUMMARY OF BACKGROUND DATA: MIS TLIF has been utilized as a technique for decreasing patients' immediate postoperative pain, decreasing blood loss, and shortened hospital stays. Effectiveness and complications of rhBMP-2's use in the disk space is limited because of its off-label status. METHODS: Retrospective analysis of consecutive MIS TLIFs performed by senior author between 2004 and 2014. rhBMP-2 was used in the disk space in all cases. Patients were stratified based on the dose of rhBMP-2 utilized. Patients had 9 to 12 month computerized tomography scan to evaluate for bony fusion and continued follow-up for 18 months. RESULTS: A total of 688 patients underwent a MIS TLIF. A medium kit of rhBMP-2 was utilized in 97 patients, and small kit was used in 591 patients. Fusion rate was 97.9% and this was not different between the 2 groups with 96/97 patients fusing in the medium kit group and 577/591 patients fusing in the small kit group. Five patients taken back to the operating room for symptomatic pseudoarthrosis, 4 reoperated for bony hyperostosis, and 10 radiographic pseudoarthroses that did not require reoperation. A statistically significant difference in the rate of foraminal hyperostosis was found when using a medium sized kit of rhBMP-2 was 4.12% (4/97 patients), compared with a small kit (0/591 patients, P=0.0004). CONCLUSIONS: Utilization of rhBMP-2 in an MIS TLIF leads to high fusion rate (97.9%), with an acceptable complication profile. The development of foraminal hyperostosis is a rare complication that only affected 0.6% of patients, and seems to be a dose related complication, as this complication was eliminated when a lower dose of rhBMP-2 was utilized. LEVEL OF EVIDENCE: Level IV.

Comparison Perioperative Factors During Minimally Invasive Pre-Psoas Lateral Interbody Fusion of the Lumbar Spine Using Either Navigation or Conventional Fluoroscopy.

STUDY DESIGN: Retrospective clinical study. OBJECTIVES: The aim of this study was to compare intraoperative conditions and clinical results of patients undergoing pre-psoas oblique lateral interbody fusion (OLIF) using navigation or conventional fluoroscopy (C-ARM) techniques. METHODS: Forty-two patients (22 patients by navigation and 20 by fluoroscopy) underwent the OLIF procedure at 2 medical centers, and records were reviewed. Clinical data was collected and compared between the 2 groups. Patients were followed-up with a range of 6 to 24 months. RESULTS: There were no significant differences on demographic data between groups. The navigation group had zero radiation exposure (RE) to the surgeon and radiation time compared to the C-ARM group, with total RE of 44.59 ± 26.65 mGy and radiation time of 88.30 ± 58.28 seconds (P < .05). The RE to the patient was significantly lower in the O-ARM group (9.38 mGy) compared to the C-ARM group (44.59 ± 26.65 mGy). Operating room time was slightly longer in the navigation group (2.49 ± 1.35 hours) compared to the C-ARM group (2.30 ± 1.17 hours; P > .05), although not statistically significant. No differences were found in estimated blood loss, length of hospitalization, surgery-related complications, and outcome scores with an average of 8-month follow-up. CONCLUSIONS: Compared with C-ARM techniques, using navigation can eliminate RE to surgeon and decrease RE to the patient, and it had no significant effect on operating time, estimated blood loss, length of hospitalization, or perioperative complications in the patients with OLIF procedure. This study shows that navigation is a safe alternative to fluoroscopy during the OLIF procedure in the treatment of degenerative lumbar conditions.

Instrumented Lumbar Corpectomy and Spinal Reconstruction Comparing rhBMP-2/Compression-Resistant Matrix, rhBMP-2/Absorbable Collagen Sponge/Ceramic Granules Mixture, and Autograft in Two Different Devices: A Study in Sheep.

STUDY DESIGN: Fusion success with rhBMP-2 and autograft in titanium or PEEK corpectomy devices was evaluated in a sheep lumbar corpectomy model. The 6 treatment groups included titanium mesh or PEEK corpectomy devices filled with rhBMP-2 on a compression-resistant matrix (CRM) carrier; rhBMP-2 in a morselized absorbable collagen sponge (ACS) carrier combined with resorbable ceramic granules; and autograft. OBJECTIVE: The aim of this study was to determine fusion rates associated with 2 different preparations of rhBMP-2 as well as autograft in an instrumented ovine lumbar corpectomy model 6 months postoperatively. SUMMARY OF BACKGROUND DATA: Vertebral reconstruction with corpectomy devices requires bone graft. Bone graft substitutes have the potential to avoid a second operation, donor site pain, and attendant morbidity associated with autograft. METHODS: Twenty-four sheep in 6 treatment groups underwent lumbar corpectomy via a retroperitoneal trans-psoas approach. Spines were reconstructed with autograft, rhBMP-2 on a CRM, or rhBMP-2 on an ACS mixed with ceramic granules. Grafting materials were placed in either a titanium mesh or PEEK conduit in spines with internal fixation. Computed tomographic (CT) scans were evaluated for fusion. Undecalcified histology was used to evaluate for fusion as well as the amount and extent of graft incorporation and graft resorption. RESULTS: Regardless of corpectomy device used, rhBMP-2/CRM or rhBMP-2/ACS with MASTERGRAFT resulted in a 100% fusion rate. The autograft group had a lower (75%) radiographic fusion rate. Using either preparation of rhBMP-2 resulted in the length of the defect filling with solid bone. Autograft fragments and ceramic granules were incorporated into the fusion masses with much of the ceramic granules being resorbed by 6 months. CONCLUSION: Both of the rhBMP-2 formulations have the potential to effect bony fusion and vertebral reconstruction within the corpectomy devices.

Intraoperative cone beam-computed tomography with navigation (O-ARM) versus conventional fluoroscopy (C-ARM): a cadaveric study comparing accuracy, efficiency, and safety for spinal instrumentation.

STUDY DESIGN: Cadaveric laboratory study. OBJECTIVE: To compare the accuracy, efficiency, and safety of intraoperative cone beam-computed tomography with navigation (O-ARM) with traditional intraoperative fluoroscopy (C-ARM) for the placement of pedicle screws. SUMMARY OF BACKGROUND DATA: Radiation exposure remains a concern with traditional methods of intraoperative imaging in spine surgery. The use of O-ARM has been proposed for more accurate and efficient spinal instrumentation. Understanding radiation imparted to patients and surgeons by O-ARM is important for assessing risks and benefits of this technology, especially in light of evolving indications. METHODS: Four surgeons placed 160 pedicle screws on 8 cadavers without deformity. Eighty pedicle screws were placed using O-ARM and C-ARM each. Instrumentation was placed bilaterally in the thoracic (T1-T6) spine and lumbosacral junction (L5-S1) using a standard open technique, whereas minimally invasive surgery technique was used at the lumbar 3 to 4 (L3-L4) level. A "postoperative" computed tomography (CT) scan was performed on cadavers where instrumentation was done using the C-ARM. An independent musculoskeletal radiologist assessed final images for screw position. Time required to set up and instrumentation was recorded. Dosimeters were placed on multiple aspects of cadavers and surgeons to record radiation exposure. RESULTS: There were no differences in breach rate between the O-ARM and C-ARM groups (5 vs. 7, χ= 0.63, P = 0.4). The setup time for the O-ARM group was longer than that for the C-ARM group (592 vs. 297 s, P < 0.05). However, the average total time was statistically the same (1629 vs. 1639 s, P = 0.96). Radiation exposure was higher for surgeons in the C-ARM group and cadavers in the O-ARM group. When a "postoperative" CT scan was included in the estimation of the total radiation exposure, there was less of difference between the groups, but still more for the O-ARM group. CONCLUSION: In cadavers without deformity, O-ARM use results in similar breach rates as C-ARM for the placement of pedicle screws. Time for instrumentation is shorter with the O-ARM, but requires a longer setup time. The O-ARM exposes less radiation to the surgeon, but higher doses to the cadaver. LEVEL OF EVIDENCE: N/A.

Twelve-month results of a clinical pilot study utilizing pedicle-lengthening osteotomy for the treatment of lumbar spinal stenosis.

OBJECT: Lumbar spinal stenosis (LSS) is a common condition that leads to significant disability, particularly in the elderly. Current therapeutic modalities for LSS have certain drawbacks when applied to this patient population. The object of this study was to define the 12-month postoperative outcomes and complications of pedicle-lengthening osteotomies for symptomatic LSS. METHODS: A prospective, single-treatment clinical pilot study was conducted. A cohort of 19 patients (mean age 60.9 years) with symptomatic LSS was treated by pedicle-lengthening osteotomy procedures at 1 or 2 levels. All patients had symptoms of neurogenic claudication or radiculopathy secondary to LSS and had not improved after a minimum 6-month course of nonoperative treatment. Eleven patients had a Meyerding Grade I degenerative spondylolisthesis in addition to LSS. Clinical outcomes were measured using the Oswestry Disability Index (ODI), Zurich Claudication Questionnaire (ZCQ), 12-Item Short-Form Health Survey (SF-12), and a visual analog scale (VAS). Procedural variables, neurological outcomes, adverse events, and radiological imaging (plain radiographs and CT scans) were collected at the 1.5-, 3-, 6-, 9-, and 12-month time points. RESULTS: The pedicle-lengthening osteotomies were performed through percutaneous approaches with minimal blood loss in all cases. There were no operative complications. Four adverse events occurred during the follow-up period. Clinically, significant improvement was observed in the mean values of each of the outcome scales (comparing preoperative and 12-month values): ODI scores improved from 52.3 to 28.1 (p < 0.0001); the ZCQ physical function domain improved from 2.7 to 1.8 (p = 0.0021); the SF-12 physical component scale improved from 27.0 to 37.9 (p = 0.0024); and the VAS score for leg pain while standing improved from 7.2 to 2.7 (p < 0.0001). Imaging studies, reviewed by an independent radiologist, showed no evidence of device subsidence, migration, breakage, or heterotopic ossification. Thin-slice CT documented healing of the osteotomy site in all patients at the 6-month time point and an increase in the mean cross-sectional area of the spinal canal of 115%. CONCLUSIONS: Treatment of patients with symptomatic LSS with a pedicle-lengthening osteotomy procedure provided substantial enlargement of the area of the spinal canal and favorable clinical results for both disease-specific and non-disease-specific outcome measures at the 12-month time point. Future studies are needed to compare this technique to alternative therapies for lumbar stenosis.

Percutaneous pedicle screw instrumentation for temporary internal bracing of nondisplaced bony Chance fractures.

OBJECTIVE AND IMPORTANCE: Although many patients with unstable Chance fractures can heal in an external brace, others will require internal stabilization. Short-segment minimally invasive internal bracing of a Chance fracture offers the rigidity and patient compliance of internal bracing with minimal tissue disruption. This technique has not yet been described. CLINICAL PRESENTATION: A healthy 16-year-old female and 21-year-old male sustained classic nondisplaced Chance fractures. They were both neurologically intact. TECHNIQUE: An image-guided Jamshidi needle was used to percutaneously place K-wires to direct percutaneous pedicle screws. Freehand percutaneous passing of rods to connect the pedicle screw heads on each side created a short-segment construct. CONCLUSIONS: Minimally invasive internal bracing of nondisplaced bony Chance fractures is an option for selected neurologically intact patients unable to tolerate external bracing.

Unilateral pedicle screw instrumentation for minimally invasive transforaminal lumbar interbody fusion.

OBJECT: Clinical and radiographic results were assessed to determine the clinical outcomes and fusion rate in eight consecutive patients selected for minimally invasive transforaminal lumbar interbody fusion (TLIF) in which a percutaneous pedicle screw system was used unilaterally. METHODS: Eight patients underwent one-level, minimally invasive TLIF in which a percutaneous pedicle screw system was used only on the side where facets were removed for interbody access. Clinical, economic, functional, and radiographic data were recorded preoperatively and at 6 months postoperatively. The mean 6-month change in the modified Prolo Scale score was 7, and osseous interbody bridging assessed on coronal and sagittal computerized tomography studies was seen in all patients. CONCLUSIONS: The use of unilateral percutaneous pedicle screw instrumentation for the minimally invasive TLIF procedure provides excellent clinical results and is an option in selected patients.

Anterior transvertebral interbody cage with posterior transdiscal pedicle screw instrumentation for high-grade spondylolisthesis. Technical note.

Adult high-grade degenerative spondylolisthesis represents the extreme end of the spectrum for spondylolisthesis and is consequently rarely encountered. Surgical management of high-grade spondylolisthesis requires constructs capable of resisting the shear forces at the slipped L5-S1 interspace. The severity of the slip, sacral inclination, and slip angle may make conventional approaches to 360 degrees fusion difficult or hazardous. Transdiscal pedicle screw fixation, transvertebral fibular graft fusion, and transvertebral cage fixation are techniques that have been developed to establish anterior column load sharing and to resist shear forces at the L5-S1 interspace, given the anatomical constraints accompanying high-grade spondylolisthesis. In this technical note the authors describe the procedure for implanting an in situ anterior L5-S1 transvertebral cage and performing L4-5 anterior lumbar interbody fusion, followed by placement of posterior S1-L5 vertebral body transdiscal pedicle screws for management of high-grade spondylolisthesis.