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Study Design Retrospective Cohort StudyObjective To determine the incidence of vertebral artery injury (VAI), risk factors, intervention, associated complications, and mortality in patients undergoing anterior cervical corpectomy.Methods We performed a retrospective review of the incidence of VAI during anterior cervical corpectomy using the PearlDiver database from 2010-2017. The CPT code 63 081 to identify corpectomy patients. Patient data extracted included, incidence of VAI, demographic factors, intervention, and future complications of death and stroke. The risk were calculated compared with those patients who did not have VAI.Results 26 126 patients were identified to have undergone cervical corpectomy. Multivariate analysis of risk factors showed that younger age and male sex were associate with higher rate of injury (t = -11.5; P< .0001 and t = 3.8; P= .0001, respectively). Vertebral artery injuries occurred in 78 patients at an incidence of .3%. 11 (14%) VAI patients had a cerebral infarction compared with 1705 (7%) for non-VAI patients (OR = 2.13; 95% CI = [1.18 – 3.85; P= .0179]) during the follow up period. 1-year mortality rates were higher in patients who suffered a VAI (14%) compared to those who did not suffer a VAI (4%; OR = 3.85; CI = [2.04 – 7.14]; P< .0001).Conclusion Consequence of VAI may not be known for months following the injury. Although the same admission mortality is rare with this injury, there is a significant increase in post-discharge complications. This study suggests that further investigations into long term health risk of VAI is needed.

A patient's use of the emergency department (ED) is associated with factors such as limited access to primary care, chronic illnesses, poor social well-being, healthcare literacy, and substance abuse. This study examined how preoperative ED utilization affected the outcomes of anterior cervical discectomy and fusion (ACDF) procedure.

Over the past two decades, there has been a notable increase in lumbar fusion procedures. In 2011, spinal fusion surgeries in the United States incurred the highest overall costs among all surgical procedures. Extensive evidence, including multicenter randomized-controlled trials, supports the use of surgery for lumbar spondylolisthesis and stenosis. However, the growing aggregate cost of these procedures has drawn the attention of healthcare payers, policymakers, and physicians. Prior research has indicated that long-term non-operative treatments before fusion are cost-inefficient, and surgical treatment for lumbar spondylolisthesis is a cost-effective strategy. Nevertheless, there is a lack of data regarding the long-term cost difference between patients treated with lumbar spondylolisthesis surgery and those without surgery when examining a comprehensive national database.

Chronic back pain after a spinal fusion is multifactorial, but one factor is the development of adjacent segment disease, which occurs at a pooled annual incidence of about 2% a year. Fusion constructs extending to the sacrum increase angular motion and stress across the sacroiliac (SI) joint, which can lead to accelerated degeneration of the joint. The rate of SI joint degeneration after lumbar/lumbosacral fusion has been reported in one prospective study to be upwards of 75%, which was significantly higher than the control group of 38.2%. Because of the high incidence of degeneration after spinal fusions, some surgeons advocate for simultaneous SI joint fusion at the time of the primary spinal fusion. In a retrospective analysis of a prospectively maintained database, none of the patients undergoing simultaneous SI joint fusion with spinal fusion experienced postoperative SI joint pain, while 44.6% of those without simultaneous SI joint fusion did develop such pain. However, most studies have been institution-specific reporting and subsequent systematic reviews. There has been no large-scale database study looking at the risk factors for future SI joint fusion after spinal fusion.

Adjacent segment disease (ASD) is one of the most common complications after spinal fusion, occurring a rate of approximately 2% a year. Increased loading and mobility at the adjacent segments are theorized mechanisms of ASD. The paraspinal muscles act as dynamic stabilizers of the lumbar spine and recently the suboptimal quality of the musculature such as increased fat infiltration has been implicated as a potential risk factor for ASD and need for subsequent surgery.

Study design: This is a retrospective chart review.Objectives: To identify the incidence of, and variables correlated with, femoral ring allograft (FRA) fracture following anterior lumbar interbody fusion (ALIF).Methods: All patients who underwent ALIF using FRAs at an academic institution over 10 years were included. Postoperative radiographs were reviewed by both the primary and senior authors; fracture and no-fracture groups were created for comparison. Patient and surgical characteristics were extracted from electronic medical records. Frequency data comparisons were performed using contingency table analysis; comparisons of means were analyzed for continuous variables. A multivariate linear regression model was developed using screw use, graft height <12 mm, index level, and weight as variables.Results: A total of 76 FRAs in 59 patients were identified, 13 (17%) of which fractured. Age, sex, smoking status, use of buttress screws, weight, index level, and presence of spondylolisthesis were not correlated with incidence of fracture (P> .05). There was a significant correlation between the height of FRA and incidence of fracture; 2% (1/52) of grafts ≥12 mm and 50% (12/24) of grafts <12 mm fractured (P< .0001). Using ordinary least-squares regression, this result was independent of patient weight, use of screws, and index level. Of 10 patients, 9 did not require revision surgery to achieve fusion.Conclusions: Graft height was the only variable correlated with incidence of FRA fracture. Graft height <12 mm is an independent risk factor for FRA fracture in patients undergoing ALIF, and their use should be avoided in ALIF procedures.

Study Design Retrospective Cohort Study.Objective To identify risk factors for sacroiliac (SI) joint fusion after instrumented spinal fusion.Methods Patients were identified from the PearlDiver BiscayneBay database. Patients who underwent 1 level (CPT: 22840), 3-6 vertebral segment (22842), and 7+ vertebral segment spinal fusions (22843 and 22844) were identified. Patients were separated based on whether they received an SI joint fusion (27280 and 27279) after their spinal fusion. A univariate analysis and multivariate logistic regression was performed to evaluate the associations between patient factors and incidence of SI joint fusion.Results 549,625 patients who underwent posterior spinal fusions were identified, 6068 of whom underwent subsequent SI joint fusion (1.1%). Factors associated with future SI joint fusion included female gender, patients with obesity, fibromyalgia, diabetes, tobacco use, increased construct length, and prior SI joint injection. Prior SI joint injection had the highest odds ratio (OR: 8.70; 95% CI: 8.25-9.16; P< 0.001), followed by 7+ vertebral segment (OR: 2.17; 95% CI: 2.03-2.33; P< 0.001) and 3-6 vertebral segment fusion (OR: 1.49; 95% CI: 1.42-1.57; P< 0.001).Conclusions The highest predictor of requiring subsequent SI joint fusion is a prior SI joint injection. We also found that longer fusion constructs are associated with increased risk for future SI joint fusion.

Study Design Retrospective Cohort Study.Objectives This study aimed to examine the effect of state legislation on prescribing behavior after a commonly performed spinal procedure, posterior lumbar interbody fusion (PLIF).Methods Two cohorts of patients from the Pearl Diver Database were created based on patients who underwent PLIF surgery in 2014-15 and 2018-19. We compared opioid prescription rates and morphine-milli-equivalent (MME) between states with and without prescription legislation.Results We analyzed 50 958 PLIF patients from 2014-15 and 46 751 patients from 2018-19. Among them, 38 states passed opioid prescription laws in 2016-2017, while 12 states did not. The percentage of patients receiving opioid prescriptions within 365 days post-surgery remained similar in both time periods (49% in 2014-15 and 48% in 2018-2019). This trend was consistent across states with and without prescription legislation (50% vs 48% in 2014-2015, and similar in 2018-19). Opioid prescription quantity significantly decreased in all states between 2014-15 and 2018-19. In states with legislation, average MME dropped from 9198 ± 21 002 to 4932 ± 13 213 (46.4% decrease), and in states without legislation, it decreased from 9175 ± 21 032 to 4994 ± 11 687 (45.6% decrease). However, these differences were not statistically significant (P= .7985).Conclusion From 2014 to 2018, there was a significant decrease in the number of opioids prescribed after PLIF. However, this decrease occurred irrespective of state legislation on prescribing practices being passed. We believe the reduction in opioids prescribed was due to increased awareness surrounding the dangers of opioids among physicians.

Tissue engineering utilizes scaffolds containing chondrogenic cells to promote cartilage development at a clinically relevant scale, yet there remains a limited understanding of the optimal conditions for inducing differentiation and matrix production. We investigated how cell density and temporal exposure to chondrogenic factors impacted chondrogenesis of human mesenchymal stem cells (hMSCs) encapsulated in poly(ethylene glycol) diacrylate hydrogels. We found maximal proteoglycan and collagen production in constructs seeded between 10 and 25 × 106cells/mL. Matrix deposition was significantly less per cell in constructs seeded at either higher or lower densities, indicating that paracrine communications may remain important despite loss of direct cell–cell contact. In vitrochondrogenesis of hMSCs was first accomplished using pellet cultures and a defined medium containing transforming growth factor (TGF)-β1 and dexamethasone. The differentiation of hMSCs in hydrogels also required initial exposure to TGF-β1, with no chondrogenic matrix produced in its absence. If TGF-β1 was initially included for at least 7 days, its removal impacted collagen production per cell but also lead to an increase in cell number, such that total collagen deposition was equivalent to controls when TGF-β1 was included for at least 3 weeks. Further, proteoglycan content per construct was higher at 6 weeks after removal of TGF-β1 at any time. In contrast to TGF-β1, dexamethasone was not required for chondrogenesis of hMSCs in hydrogels: there was no difference in matrix deposition between hydrogels cultured with or without dexamethasone. Further, without dexamethasone, SOX9gene expression was higher during early chondrogenesis and there was a significant reduction in collagen I deposition, suggesting that a more hyaline cartilage phenotype is achieved without dexamethasone. Collagen content at 6 weeks was lower if dexamethasone was excluded after the first 7 days, but was equivalent to control if dexamethasone was included for 2 weeks or longer. Proteoglycan deposition was unaffected by dexamethasone exclusion. These results indicate that modulating exposure to TGF-β1 is beneficial for cell survival/proliferation and matrix production from hMSCs in hydrogels, and that not only is dexamethasone dispensable but also its exclusion may be advantageous for forming hyaline cartilage.

Describe the use of a radiographic parameter (pelvic incidence) to assess the sagittal plane reduction of H-type sacral fractures associated with spinopelvic dissociation, and assess the relationship between standing lumbar lordosis to pelvic incidence after spinopelvic dissociation.

We describe a surgical radiographic technique during anterior cervical corpectomy to define the safe lateral limit of dissection.

Airway difficulties after single-stage, multilevel anterior and posterior cervical surgery are potentially life-threatening complications. Although extubation delays can occur, overnight intubation can reduce the risk of postoperative airway emergencies. Our protocol was as follows all patients were kept intubated overnight in an intensive care unit and examined by the intensive care unit staff each morning. Readiness for extubation was based on the cuff-leak test, and extubation done on patients beyond the first postoperative day was considered delayed. Eleven patients were extubated on the first postoperative day (group 1), and 11 extubated beyond day 1 (group 2). No airway emergencies occurred. Patient factors—age, weight, smoking, medical comorbidities, American Society of Anesthesiologist class—were not significantly related to extubation delay. There were no differences between groups in the number of anterior and posterior levels or anterior and posterior operative times. Delayed extubation was significantly related to total operative time (8.2 hours vs. 10.6 hours), volume of crystalloid replacement (3627 cm3vs. 6218 cm3) and intraoperative blood transfused (0.7 units vs. 3.1 units); approaching significance was increased blood loss (1238 mL vs. 2820 mL). We have found intraoperative factors—operative time, crystalloid volume, blood loss and replacement—rather than patient characteristics, to be risk factors for delayed extubation. Good communication with anesthesia staff and careful attention to postoperative airway management is essential after single-stage, multilevel anterior cervical decompression and posterior fusion.

Both the cadaveric and clinical examples of anomalous vertebral artery courses are described. The incidence of this anomaly in the general population and recognition, complications, and treatment options for these patients when undergoing anterior cervical decompression are discussed.

The biological signals at the site of injury allow mesenchymal progenitor cells to migrate, proliferate, and differentiate into appropriate repair tissues. These cells are ubiquitously present throughout the body, and they can differentiate to osteoblast, chondrocyte, fibroblast, and adipocytes under appropriate conditions. Failure of repair may be due to an inadequate progenitor cell response to the injury.

Articular cartilage in adults has limited ability for self‐repair. Some methods devised to augment the natural healing response stimulate some regeneration, but the repair is often incomplete and lacks durability. Hyaluronan‐based polymers were tested for their ability to enhance the natural healing response. It is hypothesized that hyaluronan‐based polymers recreate an embryonic‐like milieu where host progenitor cells can regenerate the damaged articular surface and underlying bone. Osteochondral defects were made on the femoral condyles of 4‐month‐old rabbits and were left empty or filled with hyaluronan‐based polymers. The polymers tested were ACP sponge, made of crosslinked hyaluronan, and HYAFF‐11 sponge, made of benzylated hyaluronan. The rabbits were killed 4 and 12 weeks after surgery, and the condyles were processed for histology. All 12‐week defects were scored with a 29‐point scale, and the scores were compared with a Kruskall‐Wallis analysis of variance on ranks. Untreated defects filled with bone tissue up to or beyond the tidemark, and the noncalcified surface layer varied from fibrous to hyaline‐like tissue. Four weeks after surgery, defects treated with ACP exhibited bone filling to the level of the tidemark and the surface layer was composed of hyaline‐like cartilage well integrated with the adjacent cartilage. At 12 weeks, the specimens had bone beyond the tidemark that was covered with a thin layer of hyaline cartilage. Four weeks after surgery, defects treated with HYAFF‐11 contained a rim of chondrogenic cells at the interface of the implant and the host tissue. In general, the 12‐week defects exhibited good bone fill and the surface was mainly hyaline cartilage. Treated defects received significantly higher scores than untreated defects (p < 0.05), and ACP‐treated defects scored significantly higher than HYAFF‐11‐treated defects (p < 0.05). The introduction of these hyaluronan‐based polymers into defects provides an appropriate scaffolding and favorable microen‐vironment for the reparative process. Further work is required to fully assess the long‐term outcome of defects treated with these polymers.

This study examines the C2 vertebrae using both direct anatomic and computed tomographic measurements.

To assess the chondrogenic potential of cells within the synovium. Explants of synovium taken from various sites in the joint were embedded in agarose and cultured with transforming growth factor β1 (TGFβ1) to assess their chondrogenic potential. Isolated synovial cells were also tested for their chondrogenic potential by culturing them as aggregates in a chemically defined medium with TGFβ1. Cartilage formation was determined with histologic staining and immunohistochemistry. The osteochondral potential of the isolated cells was also assessed after subcutaneous implantation of the cells, loaded into porous calcium phosphate ceramic cubes, in athymic mice. A total of 48 synovial explants were cultured in agarose with TGFβ1. The formation of cartilage was observed in the outer region of 21 explants, and type II collagen was localized in that region by immunohistochemistry. A larger percentage of TGFβ1+ explants from the inner synovium sites formed cartilage compared with those from the outer synovium sites. Chondrogenesis occurred in aggregates incubated with TGFβ1 as early as day 7, and by day 14, all TGFβ1+ aggregates demonstrated chondrogenesis. In contrast with the results of the in vitro aggregate assay for chondrogenesis, no formation of cartilage or bone was evident in any section containing synovial cell–loaded ceramic cubes that were harvested at either 3 or 6 weeks after implantation subcutaneously in athymic mice. Synovial explants and isolated synovial cells will undergo chondrogenesis when cultured in the presence of TGFβ1. The data indicate a possible synovial origin for the chondrocytic cells found in rheumatoid pannus. Furthermore, these data are consistent with the clinical findings of synovial chondrogenesis leading to synovial chondromatosis.

The rabbit has been extensively used for preclinical models, especially in orthopedic applications. One of the more troubling features of this model is the high interindividual variability that is encountered and that requires a careful experimental design with sufficient sample size to make judgments valid. We have processed 241 individual preparations of rabbit bone marrow-derived mesenchymal progenitor cells (MPCs) over the last 3 years and have kept detailed records of the performance of these cells in various assays. This communication details the lack of correlation between the analyzed parameters. Bone marrow was harvested from 4-month-old rabbits; the cells were centrifuged, resuspended, and cultured. When cells reached 80% of confluence, they were removed from the plates with trypsin and assayed for their osteo- and chondrogenic potential. The average yield of the 241 individual MPC preparations exhibited a coefficient of variation of 77. An in vivo implantation assay with porous calcium phosphate ceramic cubes exhibited scores with a coefficient of variation of 65. Lastly, an in vitro assay of alkaline phosphatase enzyme activity exhibited the most variability with a coefficient of variation of 132. All of the cell preparations tested in an in vitro aggregate culture assay underwent chondrogenic differentiation. No relationships between any of these parameters were found. The variability of the results within the different assays is interpreted to be the result of the heterogeneity of the preparations. The lack of correlation between the parameters studied shows the importance of the conditions intrinsic to the different assays. These results serve to emphasize that any experimental design involving rabbit progenitor cells must include a sufficiently large sample size to allow statistically significant and rigorous conclusions.

Posterolateral spinal fusion with autologous bone marrow aspirate in addition to autograft iliac crest bone graft in a rabbit model.

Adult marrow contains mesenchymal progenitor cells (MPCs) that have multiple differentiation potentials. A conditionally immortalized MPC clone, BMC9, has been identified that exhibits four mesenchymal cell phenotypes: chondrocyte, adipocyte, stromal (support osteoclast formation), and osteoblast. The BMC9 clone, control brain fibroblasts and another marrow‐derived clone, BMC10, were isolated from a transgenic mouse (H‐2Kb‐tsA58) containing a gene for conditional immortality. To test for chondrogenic potential, cells were cultured in defined medium containing 10 ng/ml transforming growth factor β and 10−7M dexamethasone in 15‐ml polypropylene tubes (“aggregate cultures”). Adipogenic potential was quantitated by flow cytometry of Nile Red–stained cells cultured for 1 and 2 weeks in medium containing isobutyl methylxanthine, indomethacin, insulin, and dexamethasone. Support of osteoclast formation was measured by quantitating multinucleated tartrate‐resistant acid phosphatase–positive cells in spleen cell cocultures of test clones (immortomouse clones and positive control ST2 cells) cultured in the presence of 10−7M vitamin D3and 150 mM ascorbate‐2‐phosphate. In vivo osteogenic potential was assayed by histologic examination of bone formation in subcutaneous implants, into athymic mouse hosts, of a composite of cells combined with porous calcium phosphate ceramics. The bone marrow–derived clone BMC9 has the potential to express each of the four mesenchymal characteristics tested, while brain fibroblasts, tested under identical conditions, did not exhibit any of these four mesenchymal characteristics. BMC10 cells exhibited osteogenic and chondrogenic phenotypes, but showed only minimal expression of adipocytic or osteoclast‐supportive phenotypes. Clone BMC9 is, minimally, a quadripotential MPC isolated from the marrow of an adult mouse that can differentiate into cartilage and adipose, support osteoclast formation, and form bone. The BMC9 clone is an example of an adult‐derived multipotential progenitor cell that is situated early in the mesenchymal lineage.

Adult marrow contains mesenchymal progenitor cells (MPCs) that have multiple differentiation potentials. A conditionally immortalized MPC clone, BMC9, has been identified that exhibits four mesenchymal cell phenotypes: chondrocyte, adipocyte, stromal (support osteoclast formation), and osteoblast. The BMC9 clone, control brain fibroblasts and another marrow‐derived clone, BMC10, were isolated from a transgenic mouse (H‐2Kb‐tsA58) containing a gene for conditional immortality. To test for chondrogenic potential, cells were cultured in defined medium containing 10 ng/ml transforming growth factor β and 10−7M dexamethasone in 15‐ml polypropylene tubes (“aggregate cultures”). Adipogenic potential was quantitated by flow cytometry of Nile Red–stained cells cultured for 1 and 2 weeks in medium containing isobutyl methylxanthine, indomethacin, insulin, and dexamethasone. Support of osteoclast formation was measured by quantitating multinucleated tartrate‐resistant acid phosphatase–positive cells in spleen cell cocultures of test clones (immortomouse clones and positive control ST2 cells) cultured in the presence of 10−7M vitamin D3and 150 mM ascorbate‐2‐phosphate. In vivo osteogenic potential was assayed by histologic examination of bone formation in subcutaneous implants, into athymic mouse hosts, of a composite of cells combined with porous calcium phosphate ceramics. The bone marrow–derived clone BMC9 has the potential to express each of the four mesenchymal characteristics tested, while brain fibroblasts, tested under identical conditions, did not exhibit any of these four mesenchymal characteristics. BMC10 cells exhibited osteogenic and chondrogenic phenotypes, but showed only minimal expression of adipocytic or osteoclast‐supportive phenotypes. Clone BMC9 is, minimally, a quadripotential MPC isolated from the marrow of an adult mouse that can differentiate into cartilage and adipose, support osteoclast formation, and form bone. The BMC9 clone is an example of an adult‐derived multipotential progenitor cell that is situated early in the mesenchymal lineage.

A retrospective review of all patients surgically treated for adjacent segment disease of the cervical spine over a 20year period.

Utility of using computed tomography to predict pedicle screw misplacement.

Harrington rod treatment for spinal trauma has become the gold standard against which other treatment modalities are judged. A review of the results of Harrington rod treatment is essential to establish a baseline level of efficiency in terms of rehabilitation time, correction of deformity, canal decompression, motion segment loss, and devicerelated complications. With economic concerns becoming more important in medical treatment, the value of newer techniques must be clearly superior to established methods. Harrington rodaugmented spine fusion is reliable and costeffective in the thoracic and thoracolumbar spine. The risks of rod failure and late complications related to lost motion segments in the lumbar spine make pedicle screw systems a better option in this region.

This study is a prospective evaluation of the effects of commonly used spinal tables on lumbar sagittal alignment.

A culture system that facilitates the chondrogenic differentiation of rabbit bone marrow-derived mesenchymal progenitor cells has been developed. Cells obtained in bone marrow aspirates were first isolated by monolayer culture and then transferred into tubes and allowed to form three-dimensional aggregates in a chemically defined medium. The inclusion of 10−7M dexamethasone in the medium induced chondrogenic differentiation of cells within the aggregate as evidenced by the appearance of toluidine blue metachromasia and the immunohistochemical detection of type II collagen as early as 7 days after beginning three-dimensional culture. After 21 days, the matrix of the entire aggregate contained type II collagen. By 14 days of culture, there was also evidence for type X collagen present in the matrix and the cells morphologically resembled hypertrophic chondrocytes. However, chondrogenic differentiation was achieved in only approximately 25% of the marrow cell preparations used. In contrast, with the addition of transforming growth factor-β1 (TGF-β1), chondrogenesis was induced in all marrow cell preparations, with or without the presence of 10−7M dexamethasone. The induction of chondrogenesis was accompanied by an increase in the alkaline phosphatase activity of the aggregated cells. The results of RT-PCR experiments indicated that both type IIA and IIB collagen mRNAs were detected by 7 days postaggregation as was mRNA for type X collagen. Conversely, the expression of the type I collagen mRNA was detected in the preaggregate cells but was no longer detectable at 7 days after aggregation. These results provide histological, immunohistochemical, and molecular evidence for thein vitrochondrogenic differentiation of adult mammalian progenitor cells derived from bone marrow.