Novel Vacuum-Assisted Method for Harvesting Autologous Cancellous Bone Graft and Bone Marrow From the Proximal Tibial Metaphysis.

BACKGROUND: Autogenous cancellous bone graft and bone marrow aspirate are commonly used in lower extremity fusion procedures to enhance fusion potential, and frequently in revision situations where bone loss and osteolysis may be a feature. The tibial metaphysis is a common donor site for bone graft, with the procedure typically performed using a curette or trephine to harvest the cancellous bone. Some limitations of this technique include suboptimal harvest of the marrow portion in particular, incomplete graft harvest, and loss of graft material during the harvest process. We describe a novel vacuum-assisted bone harvesting device to acquire cancellous bone and marrow from the proximal tibia. METHODS: This is a retrospective study of a single surgeon's consecutive patients who underwent foot and ankle arthrodesis procedures using proximal tibia autograft obtained using a vacuum-assisted bone harvesting device. Descriptive statistics were used to summarize patient and operative characteristics and outcomes. We identified 9 patients with a mean age of 51 years, 4 of whom were female. RESULTS: On average, the skin incision was slightly more than 2 cm, and 27 mL of solid graft and 16 mL of liquid phase aspirate were collected. At 6 weeks after the procedure, there was minimal to no pain at the donor site, and we did not observe any fractures or other complications. CONCLUSIONS: We report the use of a novel vacuum-assisted curette device to harvest bone graft from the proximal tibial metaphysis for use in foot and ankle fusions. This device has been reliable and efficient in clinical practice. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Underweight patients are an often under looked "At risk" population after undergoing posterior cervical spine surgery.

BACKGROUND: Body Mass Index (BMI) is a weight-for-height metric that is used to quantify tissue mass and weight levels. Past studies have mainly focused on the association of high BMI on spine surgery outcomes and shown variable conclusions. Prior results may have varied due to insufficient power or inconsistent categorical separation of BMI groups (e.g. underweight, overweight, or obese). Additionally, few studies have considered outcomes of patients with low BMI. The aim of the current study was to analyze patients along the entirety of the BMI spectrum and to establish specific granular BMI categories for which patients become at risk for complication and mortality following posterior cervical spine surgery. METHODS: Patients undergoing elective posterior cervical spine surgery were abstracted from the 2005-2016 National Surgical Quality Improvement Program (NSQIP) databases. Patients were aggregated into pre-established WHO BMI categories and adverse outcomes were normalized to average risk of normal-weight subjects (BMI 18.5-24.9 kg/m2). Risk-adjusted multivariate regressions were performed controlling for patient demographics and overall health. RESULTS: A total of 16,806 patients met inclusion criteria. Odds for adverse events for underweight patients (BMI < 18.5 kg/m2) were the highest among any category of patients along the BMI spectrum. These patients experienced increased odds of any adverse event (Odds Ratio (OR) = 1.67, p = 0.008, major adverse events (OR=2.08, p = 0.001), post-operative infection (OR = 1.95, p = 0.002), and reoperation (OR = 1.84, p = 0.020). Interestingly, none of the overweight or obese categories were found to be correlated with increased risk of adverse event categories other than super-morbidly obese patients (BMI>50.0 kg/m2) for post-operative infection (OR = 1.54, p = 0.041). CONCLUSIONS: The current study found underweight patients to have the highest risk of adverse events after posterior cervical spine surgery. Increased pre-surgical planning and resource allocation for this population should be considered by physicians and healthcare systems, as is often already done for patients on the other end of the BMI spectrum.

Spinal fractures and/or spinal cord injuries are associated with orthopedic and internal organ injuries in proximity to the spinal injury.

BACKGROUND: the demographics, mechanisms of injury, and concurrent injuries associated with cervical, thoracic and lumbar spinal fracture and/or spinal cord injury remain poorly characterized. METHODS: Patients aged 18 and older with spinal injury between 2011 and 2015 in the National Trauma Data Bank (NTDB) were identified. Patient demographics, comorbidity burden, mechanism of injury, and associated injuries were analyzed. RESULTS: in total, 520,183 patients with acute spinal injury were identified including 216,522 cervical, 191,218 thoracic, and 220,294 lumbar. The age distributions were trimodal with peaks in incidence at around 2155 and a lesser peak around 85 years of age. The number of comorbidities increased while injury severity decreased with advancing patient age. Motor vehicle accidents (MVAs) were the most common mechanism of injury. Associated bony and internal organ injuries were common and occurred in 63% of cervical spine injury patients, 79% of thoracic spine injury patients, and 71% of lumbar spine injury patients. In all three sub-populations, there was a predominance of injuries in the local area of the primary injury. For cervical, these were rib injuries (28%), thoracic spine injuries (22%), skull fractures (20%), intracranial injuries (26%) and lung injuries (21%). For thoracic, these were rib injuries (47%), lumbar spine injuries (26%), cervical spine injuries (25%), lung injuries (35%) and intracranial injuries (24%). For lumbar, these were rib injuries (38%), thoracic spine injuries (22%), pelvic fractures (20%), lung injuries (26%) and intracranial injuries (19%). Multivariate regression analysis demonstrated that increased injury severity was strongly correlated with increased mortality, with lesser contributions from increased age and comorbidity burden. CONCLUSIONS: the current study revealed spinal fractures and/or cord injuries had high incidences of associated injuries that had a predominance of local distribution. These findings, in combination with the mortality analysis, demonstrate the importance of local targeted evaluations for associated injuries.

Coagulopathies Are a Risk Factor for Adverse Events Following Total Hip and Total Knee Arthroplasty.

Current literature suggests a correlation between preoperative coagulopathies and postsurgical adverse events (AEs). However, this correlation has not been specifically assessed in the total hip arthroplasty (THA) and the total knee arthroplasty (TKA) populations. Patients who underwent primary THA and TKA with coagulopathy data were identified from the 2011-2015 American College of Surgeons National Surgical Quality Improvement Program database. Coagulopathies studied were low platelets, high partial thromboplastin time (PTT), high international normalized ratio (INR), and other hematological conditions. Univariate and multivariate analyses were conducted to explore the relationship between coagulopathies and 30-day AEs following surgery in these populations. In total, 39,605 THA patients and 67,685 TKA patients were identified. Of these, approximately 16% had a coagulopathy. These patients tended to be older and have a dependent functional status, American Society of Anesthesiologists score of 3 or greater, and diabetes mellitus. In the THA cohort, low platelets, high PTT, high INR, and other hematological conditions were associated with increased odds of any AE, major AEs, and minor AEs. High INR and other hematological conditions were associated with an increased odds of hospital readmission. In the TKA group, low platelets, high INR, and other hematological conditions were associated with increased odds of any AE, major AEs, and minor AEs. High PTT was associated with increased odds of major AEs and readmissions. Presence of a coagulopathy was associated with multiple AEs following both THA and TKA. This shows that special attention should be paid patients with any form of coagulopathy to minimize the potential risk of AEs. [Orthopedics. 2020;43(4):233-238.].

Industry Payments to Orthopedic Spine Surgeons Reported by the Open Payments Database: 2014-2017.

STUDY DESIGN: This was a retrospective study of publicly available data. OBJECTIVE: The objective of this study was to characterize and assess trends in Open Payments Database (OPD) industry payments reported to orthopedic spine surgeons from 2014 to 2017. SUMMARY OF BACKGROUND DATA: There have been a lack of studies characterizing OPD industry payments to orthopedic spine surgeons over the 4 full years of data available. MATERIALS AND METHODS: General industry payments made to orthopedic spine surgeons from 2014 to 2017 were characterized by year with analysis of: number of compensated surgeons, median payment per surgeon, top strata of compensated surgeons, and subtype (ie, food/beverage). Research and Ownership Payments were characterized by median payment per surgeon. Mann-Whitney U tests were used to compare payments. RESULTS: For General Payments, the number of compensated orthopedic spine surgeons increased from 1539 in 2014 to 1673 in 2017. Later year median General Payments per surgeon were compared with the 2014 median ($1051): 2015 ($1070: P=0.375), 2016 ($1263: P=0.012), and 2017 ($978: P=0.561). In 2014, the top 10% of compensated orthopedic spine surgeons received 89% of the total General compensation to orthopedic spine surgeons, top 5% received 79%, and the top 1% received 55%. The median General Payment for these 3 top strata remained similar over the 4 years evaluated (P>0.05). For subtype analyses, the median aggregate General Payment for "education" increased (P=0.002) across the years. Finally, it was determined that the median payment per surgeon for Research and Ownership Payment categories remained stable across the time period (P>0.05). CONCLUSIONS: Many expected industry payments to surgeons to decrease under public scrutiny of the OPD, but the present study showed no net change in median payment (General, Research, and Ownership) over the years studied. In the age of greater transparency, these findings shed insight into the orthopedic spine surgeon-industry relationship. LEVEL OF EVIDENCE: Level III.

Differential outcomes of venous and arterial tissue engineered vascular grafts highlight the importance of coupling long-term implantation studies with computational modeling.

Electrospinning is commonly used to generate polymeric scaffolds for tissue engineering. Using this approach, we developed a small-diameter tissue engineered vascular graft (TEVG) composed of poly-ε-caprolactone-co-l-lactic acid (PCLA) fibers and longitudinally assessed its performance within both the venous and arterial circulations of immunodeficient (SCID/bg) mice. Based on in vitro analysis demonstrating complete loss of graft strength by 12 weeks, we evaluated neovessel formation in vivo over 6-, 12- and 24-week periods. Mid-term observations indicated physiologic graft function, characterized by 100% patency and luminal matching with adjoining native vessel in both the venous and arterial circulations. An active and robust remodeling process was characterized by a confluent endothelial cell monolayer, macrophage infiltrate, and extracellular matrix deposition and remodeling. Long-term follow-up of venous TEVGs at 24 weeks revealed viable neovessel formation beyond graft degradation when implanted in this high flow, low-pressure environment. Arterial TEVGs experienced catastrophic graft failure due to aneurysmal dilatation and rupture after 14 weeks. Scaffold parameters such as porosity, fiber diameter, and degradation rate informed a previously described computational model of vascular growth and remodeling, and simulations predicted the gross differential performance of the venous and arterial TEVGs over the 24-week time course. Taken together, these results highlight the requirement for in vivo implantation studies to extend past the critical time period of polymer degradation, the importance of differential neotissue deposition relative to the mechanical (pressure) environment, and further support the utility of predictive modeling in the design, use, and evaluation of TEVGs in vivo. STATEMENT OF SIGNIFICANCE: Herein, we apply a biodegradable electrospun vascular graft to the arterial and venous circulations of the mouse and follow recipients beyond the point of polymer degradation. While venous implants formed viable neovessels, arterial grafts experienced catastrophic rupture due to aneurysmal dilation. We then inform a previously developed computational model of tissue engineered vascular graft growth and remodeling with parameters specific to the electrospun scaffolds utilized in this study. Remarkably, model simulations predict the differential performance of the venous and arterial constructs over 24 weeks. We conclude that computational simulations should inform the rational selection of scaffold parameters to fabricate tissue engineered vascular grafts that must be followed in vivo over time courses extending beyond polymer degradation.

Development of small diameter nanofiber tissue engineered arterial grafts.

The surgical repair of heart and vascular disease often requires implanting synthetic grafts. While synthetic grafts have been successfully used for medium-to-large sized arteries, applications for small diameter arteries (<6 mm) is limited due to high rates of occlusion by thrombosis. Our objective was to develop a tissue engineered vascular graft (TEVG) for small diameter arteries. TEVGs composed of polylactic acid nanofibers with inner luminal diameter between 0.5 and 0.6 mm were surgically implanted as infra-renal aortic interposition conduits in 25 female C17SCID/bg mice. Twelve mice were given sham operations. Survival of mice with TEVG grafts was 91.6% at 12 months post-implantation (sham group: 83.3%). No instances of graft stenosis or aneurysmal dilatation were observed over 12 months post-implantation, assessed by Doppler ultrasound and microCT. Histologic analysis of explanted TEVG grafts showed presence of CD31-positive endothelial monolayer and F4/80-positive macrophages after 4, 8, and 12 months in vivo. Cells positive for α-smooth muscle actin were observed within TEVG, demonstrating presence of smooth muscle cells (SMCs). Neo-extracellular matrix consisting mostly of collagen types I and III were observed at 12 months post-implantation. PCR analysis supports histological observations. TEVG group showed significant increases in expressions of SMC marker, collagen-I and III, matrix metalloproteinases-2 and 9, and itgam (a macrophage marker), when compared to sham group. Overall, patency rates were excellent at 12 months after implantation, as structural integrity of these TEVG. Tissue analysis also demonstrated vessel remodeling by autologous cell.

Comparison of the biological equivalence of two methods for isolating bone marrow mononuclear cells for fabricating tissue-engineered vascular grafts.

Our approach for fabricating tissue-engineered vascular grafts (TEVG), applied in the surgical management of congenital heart disease, is accomplished by seeding isolated bone marrow-derived mononuclear cells (BM-MNCs) onto biodegradable scaffolds. The current method used for isolation of BM-MNCs is density centrifugation in Ficoll. This is a time-consuming, labor-intensive, and operator-dependent method. We previously demonstrated that a simpler, faster, and operator-independent method for isolating BM-MNCs using a filter elution technique was feasible. In this study, we compare the use of each technique to determine if the BM-MNCs isolated by the filtration elution method are biologically equivalent to BM-MNCs isolated using density centrifugation. Scaffolds were constructed from a nonwoven poly(glycolic acid) fiber mesh coated with 50:50 poly(l-lactide-co-ɛ-caprolactone) sealant. BM-MNCs were isolated from the bone marrow of syngeneic C57BL/6 mice by either density centrifugation with Ficoll or filtration (Ficoll vs. Filter), then statically seeded onto scaffolds, and incubated overnight. The TEVG were implanted in 10-week-old C57BL/6 mice (n=23 for each group) as inferior vena cava interposition grafts and explanted at 14 days for analysis. At 14 days after implantation, there were no significant differences in graft patency between groups (Ficoll: 87% vs. Filter: 78%, p=0.45). Morphometric analysis by hematoxylin and eosin staining showed no difference of graft luminal diameter or neointimal thickness between groups (luminal diameter, Ficoll: 620.3±82.9 µm vs. Filter: 633.3±131.0 µm, p=0.72; neointimal thickness, Ficoll: 37.9±7.8 µm vs. Filter: 37.9±11.2 µm, p=0.99). Histologic examination demonstrated similar degrees of cellular infiltration and extracellular matrix deposition, and endothelial cell coverage on the luminal surface, in either group. Macrophage infiltration showed no difference in the number of F4/80-positive cells or macrophage phenotypes between the two experimental groups (Ficoll: 2041±1048 cells/mm(2) vs. Filter: 1887±907.7 cells/mm(2), p=0.18). We confirmed the biological equivalence of BM-MNCs, isolated using either density centrifugation or filtration, for making TEVG.

Myocardial edema as detected by pre-contrast T1 and T2 CMR delineates area at risk associated with acute myocardial infarction.

OBJECTIVES: The aim of this study was to determine whether cardiac magnetic resonance (CMR) in vivo T1 mapping can measure myocardial area at risk (AAR) compared with microspheres or T2 mapping CMR. BACKGROUND: If T2-weighted CMR is abnormal in the AAR due to edema related to myocardial ischemia, then T1-weighted CMR should also be able to detect and accurately quantify AAR. METHODS: Dogs (n = 9) underwent a 2-h coronary occlusion followed by 4 h of reperfusion. CMR of the left ventricle was performed for mapping of T1 and T2 prior to any contrast administration. AAR was defined as regions that had a T1 or T2 value (ms) >2 SD from remote myocardium, and regions with microsphere blood flow (ml/min/g) during occlusion <2 SD from remote myocardium. Infarct size was determined by triphenyltetrazolium chloride staining. RESULTS: The relaxation parameters T1 and T2 were increased in the AAR compared with remote myocardium (mean ± SD: T1, 1,133 ± 55 ms vs. 915 ± 33 ms; T2, 71 ± 6 ms vs. 49 ± 3 ms). On a slice-by-slice basis (n = 78 slices), AAR by T1 and T2 mapping correlated (R(2) = 0.95, p < 0.001) with good agreement (mean ± 2 SD: 0.4 ± 16.6% of slice). On a whole-heart analysis, T1 measurements of left ventricular mass, AAR, and myocardial salvage correlated to microsphere measures (R(2) = 0.94) with good agreement (mean ± 2 SD: -1.4 ± 11.2 g of myocardium). Corresponding T2 measurements of left ventricular mass, AAR, and salvage correlated to microsphere analysis (R(2) = 0.96; mean ± 2 SD: agreement 1.6 ± 9.2 g of myocardium). This yielded a median infarct size of 30% of the AAR (range 12% to 52% of AAR). CONCLUSIONS: For determining AAR after acute myocardial infarction, noncontrast T1 mapping and T2 mapping sequences yield similar quantitative results, and both agree well with microspheres. The relaxation properties T1 and T2 both change in a way that is consistent with the presence of myocardial edema following myocardial ischemia/reperfusion.