Advances in additive manufacturing of polycaprolactone based scaffolds for bone regeneration.

Critical sized bone defects are difficult to manage and currently available clinical/surgical strategies for treatment are not completely successful. Polycaprolactone (PCL) which is a biodegradable and biocompatible thermoplastic can be 3D printed using medical images into patient specific bone implants. The excellent mechanical properties and low immunogenicity of PCL makes it an ideal biomaterial candidate for 3D printing of bone implants. Though PCL suffers from the limitation of being bio-inert. Here we describe the use of PCL as a biomaterial for 3D printing for bone regeneration, and advances made in the field. The specific focus is on the different 3D printing techniques used for this purpose and various modification that can enhance bone regeneration following the development pathways. We further describe the effect of various scaffold characteristics on bone regeneration both in vitro and the translational assessment of these 3D printed PCL scaffolds in animal studies. The generated knowledge will help understand cell-material interactions of 3D printed PCL scaffolds, to further improve scaffold chemistry and design that can replicate bone developmental processes and can be translated clinically.

Development of acetabular retroversion in LCPD hips-an observational radiographic study from early stage to healing.

BACKGROUND: Acetabular retroversion is observed frequently in healed Legg-Calvé-Perthes disease (LCPD). Currently, it is unknown at which stage and with what prevalence retroversion occurs because in non-ossified hips, retroversion cannot be measured with standard radiographic parameters. METHODS: In a retrospective, observational study; we examined pelvic radiographs in children with LCPD the time point of occurrence of acetabular retroversion and calculated predictive factors for retroversion. Between 2004 and 2017, we included 55 children with a mean age of 5.7 ± 2.4 years at diagnosis. The mean radiographic follow-up was 7.0 ± 4.4 years. We used two new radiographic parameters which allow assessment of acetabular version in non-ossified hips: the pelvic width index and the ilioischial angle. They are based on the fact that the pelvic morphology differs depending on the acetabular version. These parameters were compared among the four Waldenström stages and to the contralateral side. Logistic regression analysis was performed to determine predictive factors for acetabular retroversion. RESULTS: Both parameters differed significantly among the stages of Waldenström (p < 0.003 und 0.038, respectively). A more retroverted acetabulum was found in stage II and III (prevalence ranging from 54 to 56%) compared to stage I and IV (prevalence ranging from 23 to 39%). In hips of the contralateral side without LCPD, the prevalence of acetabular retroversion was 0% in all stages for both parameters. Predictive factors for retroversion were younger age at stage II and IV, collapse of the lateral pillar in stage II or a non-dysplastic hip. CONCLUSIONS: This is the first study evaluating acetabular version in children with LCPD from early stage to healing. In the developing hip, LCPD may result in acetabular retroversion and is most prevalent in the fragmentation (stage II) and early healing stage (stage III). Partial correction of acetabular retroversion can occur after healing. This has a potential clinical impact on the timing and type of surgical correction, especially in pelvic osteotomies for correction of acetabular version. LEVEL OF EVIDENCE: Level III, retrospective observational study.

Alginate based hydrogel inks for 3D bioprinting of engineered orthopedic tissues.

3D printed hydrogels have emerged as a novel tissue engineering and regeneration platform due to their ability to provide a suitable environment for cell growth. To obtain a well-defined scaffold with good post-printing shape fidelity, a proper hydrogel ink formulation plays a crucial role. In this regard, alginate has received booming interest owing to its biocompatibility, biodegradability, easy functionalization, and fast gelling behavior. Hence, this review highlights the significance of alginate-based hydrogel inks for fabricating 3D printed scaffolds for bone and cartilage regeneration. Herein, we discuss the fundamentals of direct extrusion 3D bioprinting method and provide a comprehensive overview of various alginate-based hydrogel ink formulations that have been used so far. We also summarize the requirements of hydrogel inks and 3D printed scaffolds to achieve similarity to the native tissue environment. Finally, we discuss the challenges, and research directions relevant for future clinical translation.

Direct 3D printing of decellularized matrix embedded composite polycaprolactone scaffolds for cartilage regeneration.

Treatment options for large osteochondral injuries (OCIs) are limited by donor tissue scarcity, morbidity, and anatomic mismatch. 3D printing technology can produce patient-specific scaffolds to address these large defects. Thermoplastics like polycaprolactone (PCL) offer necessary mechanical properties, but lack bioactivity. We fabricated 3D printed PCL scaffolds embedded with polylactic acid microspheres containing decellularized cartilage matrix (DM). DM incorporation within polylactic acid microspheres prevented its thermal degradation during the 3D printing process. The scaffolds replicated the mechanical properties of native cartilage and demonstrated controlled release of DM proteins. Human mesenchymal stem cells (hMSCs) seeded on the composite scaffolds with DM and cultured in basal media self-assembled into aggregates mimicking mesenchymal condensates during embryonic development. The DM composite scaffolds also induced higher expression of biochemical markers of cartilage development than controls, providing evidence for their translational application in the treatment of OCIs. The present study demonstrates the potential of direct incorporation of DM with thermoplastics for 3D printing of patient-specific scaffolds for osteochondral regeneration.

Pediatric and Adolescent Fractures of the Acetabulum Treated With ORIF: What Are Their Functional Outcomes?

OBJECTIVES: To evaluate the functional outcomes of pediatric and adolescent patients (<18 year old) who sustained acetabulum fractures that were treated with open reduction internal fixation (ORIF). DESIGN: Retrospective cohort. SETTING: Level 1 trauma center. PATIENTS: Thirty-four pediatric and adolescent patients underwent acetabulum fracture ORIF between 2001 and 2018. Of the operatively treated patients, 21 patients had sufficient follow-up (>6 months), one died after fixation secondary to other traumatic injuries, and 12 patients were lost to follow-up. INTERVENTION: Acetabulum fracture ORIF. MAIN OUTCOME MEASUREMENT: The SF-36 Health Survey and Short Musculoskeletal Functional Assessment (SMFA) were compared with population norms. The modified Merle d'Aubigné clinical hip score, Matta radiologic outcome, and postoperative complications were also documented. RESULTS: Functional outcome data were available at a mean of 5 years 2 months. Mean SF-36 scores were 44.8 and 50.1 for the physical component score and mental component scores, respectively, which did not differ significantly from US population norms (physical component score mean: 50, P = 0.061 and mental component score mean: 50, P = 0.973). Furthermore, the mean SMFA Bother Index score was 18.6, which is not significantly different from the population norm mean of 13.8 (P = 0.268). However, the function index mean was 31.9, which was significantly worse than the population norm mean of 12.7 (P = 0.001). Two patients with a delayed reduction (>6 hours) of an acetabulum fracture dislocation had poor outcomes related to the development of avascular necrosis and post-traumatic osteoarthritis. CONCLUSION: In this small cohort, 86% (18/21) of these patients had a favorable functional outcome with the exception of the SMFA Functional Index that was significantly less than population norms. Although long-term follow-up is needed, we advocate for operative management of pediatric and adolescent acetabulum fractures when adult displacement and instability criteria are present. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Tissue Engineering Strategies for Treating Avascular Necrosis of the Femoral Head.

Avascular necrosis (AVN) of the femoral head commonly leads to symptomatic osteoarthritis of the hip. In older patients, hip replacement is a viable option that restores the hip biomechanics and improves pain but in pediatric, adolescent, and young adult patients hip replacements impose significant activity limitations and the need for multiple revision surgeries with increasing risk of complication. Early detection of AVN requires a high level of suspicion as diagnostic techniques such as X-rays are not sensitive in the early stages of the disease. There are multiple etiologies that can lead to this disease. In the pediatric and adolescent population, trauma is a commonly recognized cause of AVN. The understanding of the pathophysiology of the disease is limited, adding to the challenge of devising a clinically effective treatment strategy. Surgical techniques to prevent progression of the disease and avoid total hip replacement include core decompression, vascular grafts, and use of bone-marrow derived stem cells with or without adjuncts, such as bisphosphonates and bone morphogenetic protein (BMP), all of which are partially effective only in the very early stages of the disease. Further, these strategies often only improve pain and range of motion in the short-term in some patients and do not predictably prevent progression of the disease. Tissue engineering strategies with the combined use of biomaterials, stem cells and growth factors offer a potential strategy to avoid metallic implants and surgery. Structural, bioactive biomaterial platforms could help in stabilizing the femoral head while inducing osteogenic differentiation to regenerate bone and provide angiogenic cues to concomitantly recover vasculature in the femoral head. Moreover, injectable systems that can be delivered using a minimal invasive procedure and provide mechanical support the collapsing femoral head could potentially alleviate the need for surgical interventions in the future. The present review describes the limitations of existing surgical methods and the recent advances in tissue engineering that are leading in the direction of a clinically effective, translational solution for AVN in future.

Fibrinogen activates focal adhesion kinase (FAK) promoting colorectal adenocarcinoma growth.

BACKGROUND: We previously showed that fibrinogen is a major determinant of the growth of a murine model of colorectal cancer (CRC). OBJECTIVE: Our aim was to define the mechanisms coupling fibrin(ogen) to CRC growth. RESULTS: CRC tumors transplanted into the dorsal subcutis of Fib- mice were less proliferative and demonstrated increased senescence relative to those grown in Fib+ mice. RNA-seq analyses of Fib+ and Fib- tumors revealed 213 differentially regulated genes. One gene highly upregulated in tumors from Fib- mice was stratifin, encoding 14-3-3σ, a master regulator of proliferation/senescence. In a separate cohort, we observed significantly increased protein levels of 14-3-3σ and its upstream and downstream targets (i.e., p53 and p21) in tumors from Fib- mice. In vitro analyses demonstrated increased tumor cell proliferation in a fibrin printed three-dimensional environment compared with controls, suggesting that fibrin(ogen) in the tumor microenvironment promotes tumor growth in this context via a tumor cell intrinsic mechanism. In vivo analyses showed diminished activation of focal adhesion kinase (FAK), a key negative regulator of p53, in Fib- tumors. Furthermore, nuclear magnetic resonance-based metabolomics demonstrated significantly reduced metabolic activity in tumors from Fib- relative to Fib+ mice. Together, these findings suggest that fibrin(ogen)-mediated engagement of colon cancer cells activates FAK, which inhibits p53 and its downstream targets including 14-3-3σ and p21, thereby promoting cellular proliferation and preventing senescence. CONCLUSIONS: These studies suggest that fibrin(ogen) is an important component of the colon cancer microenvironment and may be exploited as a potential therapeutic target.

Obesity as a Predictor of Outcomes in Type III and Type IV Supracondylar Humerus Fractures.

OBJECTIVES: To investigate the association of obesity with fracture characteristics and outcomes of operatively treated pediatric supracondylar humerus fractures. DESIGN: Retrospective multicenter. SETTING: Two Level I pediatric hospitals. PATIENTS: Patients (age <18 years) with operatively treated Gartland type III and type IV fractures 2010-2014. INTERVENTION: Closed or open reduction and percutaneous pinning of supracondylar humerus fractures. MAIN OUTCOME MEASURE: Incidence of Gartland IV fracture, preoperative nerve palsy, open reduction and complication rates. RESULTS: Patients in the obese group had a significantly higher likelihood of having a Gartland IV fracture (not obese: 17%; obese: 35%; P = 0.007). There was a significantly higher incidence of nerve palsy on presentation in the obese group (not obese: 20%; obese: 33%; P = 0.03). No significant differences were found between groups regarding incidence of open reduction, compartment syndrome, and rates of reoperation. CONCLUSIONS: The present study demonstrates that obese children with a completely displaced supracondylar humerus fractures have an increased risk of Gartland type IV and preoperative nerve palsy compared with normal weight children. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The corona mortis: is it a rare and dangerous anomaly in adolescents undergoing periacteabular osteotomy?

The corona mortis (CM) is a vascular connection between the obturator and external iliac or internal epigastric vessels that has historically been identified as a source of hemorrhage in pelvic surgery. However, its frequency, location, proximity to the osteotomies performed, vascular contributions and impact on blood loss in patients undergoing periacetabular osteotomy (PAO) are unknown. We sought to identify the frequency, origin, location relative to osteotomies performed during surgery and impact on blood loss of the CM. Preoperative magnetic resonance imaging (MRI) of the hips of 28 adolescent patients (56 hips) undergoing PAO was retrospectively reviewed for the presence of a CM. When identifiable, the size, nature (arterial or venous), orientation, position relative to the iliopectineal eminence (IPE) and associated estimated blood loss (EBL) were recorded. 75% (21/28) of patients possessed an identifiable, ipsilateral CM to the site of PAO, 90% of which were venous and 10% arterial. The vessel was typically 8.3 ± 3.8 mm medial and 11.1 ± 5.3 mm caudal from the anterosuperomedial edge of the IPE. There was no significant difference in the amount of EBL (519 ± 260 versus 694 ± 369 ml) or need for post-op transfusions (1/21 versus 0/7) between patients who possessed a CM and those who did not, respectively (P = 0.21). CM was more prevalent in this study than previously reported. However, the presence of an ipsilateral CM was not associated with an increase in EBL or transfusion during routine PAO surgery using modern surgical techniques.

Improved osseointegration using porcine xenograft compared to demineralized bone matrix for the treatment of critical defects in a small animal model.

BACKGROUND: Autograft (AG) is the gold standard bone graft due to biocompatibility, osteoconductivity, osteogenicity, and osteoinductivity. Alternatives include allografts and xenografts (XG). METHODS: We investigated the osseointegration and biocompatibility of a decellularized porcine XG within a critical defect animal model. We hypothesized that the XG will result in superior osseointegration compared to demineralized bone matrix (DBM) and equivalent immune response to AG. Critical defects were created in rat femurs and treated with XG, XG plus bone morphogenetic protein (BMP)-2, DBM, or AG. Interleukin (IL)-2 and IFN-gamma levels (inflammatory markers) were measured from animal blood draws at 1 week and 1 month post-operatively. At 1 month, samples underwent micro-positron-emission tomography (microPET) scans following 18-NaF injection. At 16 weeks, femurs were retrieved and sent for micro-computerized tomography (microCT) scans for blinded grading of osseointegration or were processed for histologic analysis with tartrate resistant acid phosphatase (TRAP) and pentachrome. RESULTS: Enzyme linked immunosorbent assay testing demonstrated greater IL-2 levels in the XG vs. AG 1 week post-op; which normalized by 28 days post-op. MicroPET scans showed increased uptake within the AG compared to all groups. XG and XG + BMP-2 showed a trend toward increased uptake compared with DBM. MicroCT scans demonstrated increased osseointegration in XG and XG + BMP groups compared to DBM. Pentachrome staining demonstrated angiogenesis and endochondral bone formation. Furthermore, positive TRAP staining in samples from all groups indicated bone remodeling. CONCLUSIONS: These data suggest that decellularized and oxidized porcine XG is biocompatible and at least equivalent to DBM in the treatment of a critical defect in a rat femur model.

Bone xenotransplantation: A review of the history, orthopedic clinical literature, and a single-center case series.

BACKGROUND: One-half of all orthopedic surgeries require bone grafting for successful outcomes in fusions, reconstructive procedures, and the treatment of osseous defects resulting from trauma, tumor, infection, or congenital deformity. Autologous bone grafts are taken from the patient's own body and remain the "gold standard" graft choice but are limited in supply and impart significant patient morbidity. Xenograft bone is an attractive alternative from donors with controlled biology, in large supply and at a theoretically lower cost. Clinical results with xenograft bone for orthopedic applications have been mixed in the limited clinical trials published. METHODS: In the current review, we introduce fundamental principles of bone grafting, systematically review all orthopedic clinical studies reporting outcomes on patients transplanted with xenograft bone, and we present our own clinical results from patients grafted with bovine bone in foot and ankle reconstructive procedures. RESULTS: Thirty-one clinical studies were identified for review and the majority (47%) were from spine surgery literature. Favorable results were reported in 44% of studies while 47% of studies reported poor outcomes and discouraged use of xenograft bone products. In our own clinical series, xenograft failed to integrate with host bone in 58% of cases and persistent pain was reported in 83% of cases. CONCLUSIONS: This is the first systematic review of clinical results reported after bone xenotransplantation for orthopaedic surgery applications. Current literature does not support the use of xenograft bone products and our institution's results are consistent with this conclusion. Our laboratory has reported promising pre-clinical results with a xenograft product derived from porcine cancellous bone, but additional testing is required before considering clinical translation.

Elucidation of bio-inspired hydroxyapatie crystallization on oxygen-plasma modified 3D printed poly-caprolactone scaffolds.

Bioapatite formation in bones is a slow process starting with deposition of calcium phosphate and then its nucleation and crystallization into hydroxyapatite crystals. If the same process can be replicated on tissue engineered scaffolds, it will result in the formation of biomimetic bone constructs that will have comparable mechanical properties to native tissue. To mimic the same process on 3D printed polycaprolactone (PCL) scaffolds oxygen plasma treatment was performed to modify their surface chemistry. The attenuated total reflectance-fourier transform infrared (ATR-FTIR) analysis showed formation of carboxyl groups on the PCL surface with corresponding increase in roughness as analyzed by atomic force microscope (AFM) studies. A biomimetic acellular mineralization procedure was then utilized to deposit calcium minerals on these scaffolds. Though amorphous calcium phosphate was deposited on all the scaffolds with highest amount on PCL scaffolds with tricalcium phosphate (TCP), biomimetic hydroxyapatite crystals were only formed on oxygen plasma treated scaffolds, as shown by X-ray diffraction (XRD) analysis. The COOH groups on the plasma treated scaffolds acted as nucleation sites for amorphous calcium phosphate and the crystal growth was observed in the (211) plane simulating the crystal growth in developing bones. The ATR-FTIR study demonstrated the carbonated nature of these hydroxyapatite crystals mimicking that of bioapatite. The electronegative COOH groups mimic the negative amino acid side chains in collagen Type I present in bone tissue and the carbonated environment helps in creating bioapatite like deposits. The present study demonstrated the important role of PCL surface chemistry in mimicking a bone like mineralization process in vitro. This work details novel insights regarding improved mineralization of 3D printed PCL scaffolds useful for the development of more biomimetic bone constructs with improved mechanical properties.

Success and efficiency of cell seeding in Avian Tendon Xenografts - A promising alternative for tendon and ligament reconstruction.

Decellularized tendon xenografts offer a promising alternative for reconstruction by using ubiquitously available material. This study compares static and centrifugal seeding of avian tendon scaffolds with NIH 3T3 fibroblasts. Incorporation of viable cells was achievable with both techniques, represented by DNA content. Proliferation rate and viability assay showed neither damage by centrifugal force nor superiority of the technique. Cell proliferation after 10 days of culture demonstrated that the scaffold did not hinder 3-D culturing. Confocal laser microscopy revealed structural details as formation of focal adhesions, to provide deeper insight into the process of cell attachment and growth in xenografts.

Pragmatic comparative effectiveness study of multimodal fascia iliaca nerve block and continuous lumbar epidural-based protocols for periacetabular osteotomy.

Perioperative pain management protocols have a significant impact on early surgical outcomes and recovery. We hypothesized that multimodal protocol including fascia iliaca compartment nerve block (MM-FICNB) would decrease the length of hospital stay (LOS) by facilitating earlier mobilization, without compromising analgesia, compared to a traditional lumbar epidural-based protocol (EP). Demographics/comorbidities, surgical/block characteristics and perioperative pain/mobilization data were collected from a prospectively recruited MM-FICNB group (N = 16) and a retrospective EP cohort (N = 16) who underwent PAO using similar surgical techniques, physical therapy/discharge criteria. Association of MM-FICNB group with LOS (primary outcome), postoperative pain, postoperative opioid requirements in morphine equivalent rates (MER) (mcg/kg/h) and time to complete physical therapy were tested using multivariable and survival regression. Patient and surgical characteristics were similar between groups. Median time for FICNB performance was significantly less than epidural (6 versus 15 min; P < 0.001). LOS was significantly decreased in the MM-FICNB group (2.88 ± 0.72 days) compared to the EP group (4.38 ± 1.02 days); P < 0.001. MM-FICNB group had significantly lower MER on POD1 (P = 0.006) and POD2 (P < 0.001), with similar pain scores on all POD. MM-FICNB group was associated with decreased LOS and earlier mobilization (P < 0.001) by covariate-adjusted multivariate regression. Cox proportional hazard regression model showed MM-FICNB subjects had 63 (95% CI 7-571, P < 0.001) times the chance of completing physical therapy goals, compared to EP. Compared to EP, MM-FICNB protocol allowed earlier mobilization and decreased post-surgical hospitalization by 1.5 days, without compromising analgesia, with important implications for value-based healthcare and cost-effectiveness.

Investigating the Osteoinductive Potential of a Decellularized Xenograft Bone Substitute.

Bone grafting is the second most common tissue transplantation procedure worldwide. One of the alternative methods for bone repair under investigation is a tissue-engineered bone substitute. An ideal property of tissue-engineered bone substitutes is osteoinductivity, defined as the ability to stimulate primitive cells to differentiate into a bone-forming lineage. In the current study, we use a decellularization and oxidation protocol to produce a porcine bone scaffold and examine whether it possesses osteoinductive potential and can be used to create a tissue-engineered bone microenvironment. The decellularization protocol was patented by our lab and consists of chemical decellularization and oxidation steps using combinations of deionized water, trypsin, antimicrobials, peracetic acid, and triton-X100. To test if the bone scaffold was a viable host, preosteoblasts were seeded and analyzed for markers of osteogenic differentiation. The osteoinductive potential was observed in vitro with similar osteogenic markers being expressed in preosteoblasts seeded on the scaffolds and demineralized bone matrix. To assess these properties in vivo, scaffolds with and without preosteoblasts preseeded were subcutaneously implanted in mice for 4 weeks. MicroCT scanning revealed 1.6-fold increased bone volume to total volume ratio and 1.4-fold increase in trabecular thickness in scaffolds after implantation. The histological analysis demonstrates new bone formation and blood vessel formation with pentachrome staining demonstrating osteogenesis and angiogenesis, respectively, within the scaffold. Furthermore, CD31+ staining confirmed the endothelial lining of the blood vessels. These results demonstrate that porcine bone maintains its osteoinductive properties after the application of a patented decellularization and oxidation protocol developed in our laboratory. Future work must be performed to definitively prove osteogenesis of human mesenchymal stem cells, biocompatibility in large animal models, and osteoinduction/osseointegration in a relevant clinical model in vivo. The ability to create a functional bone microenvironment using decellularized xenografts will impact regenerative medicine, orthopedic reconstruction, and could be used in the research of multiple diseases.

A porcine xenograft-derived bone scaffold is a biocompatible bone graft substitute: An assessment of cytocompatibility and the alpha-Gal epitope.

BACKGROUND: Xenografts are an attractive alternative to traditional bone grafts because of the large supply from donors with predictable morphology and biology as well as minimal risk of human disease transmission. Clinical series involving xenograft bone transplantation, most commonly from bovine sources, have reported poor results with frequent graft rejection and failure to integrate with host tissue. Failures have been attributed to residual alpha-Gal epitope in the xenograft which humans produce natural antibody against. To the authors' knowledge, there is currently no xenograft-derived bone graft substitute that has been adopted by orthopedic surgeons for routine clinical use. METHODS: In the current study, a bone scaffold intended to serve as a bone graft substitute was derived from porcine cancellous bone using a tissue decellularization and chemical oxidation protocol. In vitro cytocompatibility, pathogen clearance, and alpha-Gal quantification tests were used to assess the safety of the bone scaffold intended for human use. RESULTS: In vitro studies showed the scaffold was free of processing chemicals and biocompatible with mouse and human cell lines. When bacterial and viral pathogens were purposefully added to porcine donor tissue, processing successfully removed these pathogens to comply with sterility assurance levels established by allograft tissue providers. Critically, 98.5% of the alpha-Gal epitope was removed from donor tissue after decellularization as shown by ELISA inhibition assay and immunohistochemical staining. CONCLUSIONS: The current investigation supports the biologic safety of bone scaffolds derived from porcine donors using a decellularization protocol that meets current sterility assurance standards. The majority of the highly immunogenic xenograft carbohydrate was removed from donor tissue, and these findings support further in vivo investigation of xenograft-derived bone tissue for orthopedic clinical application.

A Dedicated Fracture Reduction Room: A Cost-Effective Alternative to the Operating Room.

INTRODUCTION: Charges, procedural efficiency, return to activity, and complications after closed treatment of fractures performed in an operating room (OR) versus closed reduction in a dedicated fracture reduction room (FRR) were compared. METHODS: Patients with closed fractures of the forearm who underwent closed reduction in the year before (OR), and after implementation of the FRR, were retrospectively reviewed. Charges, American Society of Anesthesiologists class, sex, age, length of follow-up, prior reduction, fracture location/displacement, time from injury to procedure, procedural time, time to return to activity, and complications were recorded. RESULTS: Eighteen patients met the inclusion criteria in the FRR group (13 men, 5 women), and 22 in the OR group (18 men, 4 women). No notable differences in age, sex, follow-up, American Society of Anesthesiologists class, fracture location/displacement, incidence of prior reduction, or time to return to activity were observed. Two (9.5%) complications occurred in the FRR group versus 7 (32%) in the OR group, P > 0.05. No anesthesia complications were present. Patients treated in the FRR incurred charges of $5,299 ± $1,289 versus $10,455 ± $2,290 in the OR, P < 0.001. Total time of visit in the FRR was ∼30% less than the OR, P < 0.001. No notable delay in treatment was observed. DISCUSSION: In the era of finite resources and value-based care, implementation of a FRR resulted in safe, cost-effective, and increased procedural efficiency.

Novel Process for 3D Printing Decellularized Matrices.

3D bioprinting aims to create custom scaffolds that are biologically active and accommodate the desired size and geometry. A thermoplastic backbone can provide mechanical stability similar to native tissue while biologic agents offer compositional cues to progenitor cells, leading to their migration, proliferation, and differentiation to reconstitute the original tissues/organs1 , 2. Unfortunately, many 3D printing compatible, bioresorbable polymers (such as polylactic acid, PLA) are printed at temperatures of 210 °C or higher - temperatures that are detrimental to biologics. On the other hand, polycaprolactone (PCL), a different type of polyester, is a bioresorbable, 3D printable material that has a gentler printing temperature of 65 °C. Therefore, it was hypothesized that decellularized extracellular matrix (DM) contained within a thermally protective PLA barrier could be printed within PCL filament and remain in its functional conformation. In this work, osteochondral repair was the application for which the hypothesis was tested. As such, porcine cartilage was decellularized and encapsulated in polylactic acid (PLA) microspheres which were then extruded with polycaprolactone (PCL) into filament to produce 3D constructs via fused deposition modeling. The constructs with or without the microspheres (PLA-DM/PCL and PCL(-), respectively) were evaluated for differences in surface features.