Fabrication of a Novel 3D Extrusion Bioink Containing Processed Human Articular Cartilage Matrix for Cartilage Tissue Engineering.

Cartilage damage presents a significant clinical challenge due to its intrinsic avascular nature which limits self-repair. Addressing this, our study focuses on an alginate-based bioink, integrating human articular cartilage, for cartilage tissue engineering. This novel bioink was formulated by encapsulating C20A4 human articular chondrocytes in sodium alginate, polyvinyl alcohol, gum arabic, and cartilage extracellular matrix powder sourced from allograft femoral condyle shavings. Using a 3D bioprinter, constructs were biofabricated and cross-linked, followed by culture in standard medium. Evaluations were conducted on cellular viability and gene expression at various stages. Results indicated that the printed constructs maintained a porous structure conducive to cell growth. Cellular viability was 87% post printing, which decreased to 76% after seven days, and significantly recovered to 86% by day 14. There was also a notable upregulation of chondrogenic genes, COL2A1 (p = 0.008) and SOX9 (p = 0.021), suggesting an enhancement in cartilage formation. This study concludes that the innovative bioink shows promise for cartilage regeneration, demonstrating substantial viability and gene expression conducive to repair and suggesting its potential for future therapeutic applications in cartilage repair.

A bending model for assessing relative stiffness and strength of orthopaedic fixation constructs.

BACKGROUND: The purpose of this study is to develop a simple and reproducible bending model that is compatible with a wide range of orthopaedic fixation devices and 3D printed spacers. METHODS: A robust 4-point bending model was constructed by securing sawbones blocks with different orthopaedic fixation device constructs. Stress strain curves derived from a fundamental mechanics model were used to assess the effect of bone density, type of hardware (staple vs intramedullary beam), the use of dynamic compression, orientation of staples (dorsal vs plantar), and the use of 3D printed titanium spacers. FINDINGS: The high throughput 4-point bending model is simple enough that the methods can be easily repeated to assess a wide range of fixation methods, while complex enough to provide clinically relevant information. INTERPRETATIONS: It is recommended that this model is used to assess a large initial set of fixation methods in direct and straightforward comparisons.

Microdrilling Resulted in Less Subchondral Bone Destruction Than a Traditional Microfracture Awl for Articular Cartilage Defect Bone Marrow Stimulation.

Purpose: The purpose of this study was to compare bone marrow stimulation using micro-computed tomography (micro-CT) analysis of an abrasion arthroplasty technique, drilling k-wire technique, traditional microfacture awl, or a microdrill instrument for subchondral bone defects. Methods: Eleven cadaveric distal femoral specimens were obtained and divided into 3 common areas of osteochondral defect: trochlea and weightbearing portions of the medial and lateral femoral condyles. Each area of interest was then denuded of cartilage using a PoweRasp and divided into quadrants. Each quadrant was assigned either a 1.6 mm Kirschner wire (k-wire), 1.25 mm microfracture awl, 1.5 mm fluted microdrill, PowerPick, or a curette (abrasion arthroplasty) to create 4 channels into the subchondral bone sing the same instrument. Subchondral bone and adjacent tissue areas were then evaluated using micro-CT to analyze adjacent bone destruction and extension into the bone marrow. Results: Overall, there was a significantly decreased area of bone destruction or compression using the microdrill (0.030 mm) as compared to the microfracture awl (0.072 mm) and k-wire (0.062 mm) (P < .05). Within the trochlea and the medial femoral condyle, there was significantly decreased bony compression with the microdrill as compared to the awl and k-wire (P < .05); however, when stratified, this was not significant among the lateral femoral condylar samples (P = .08). Conclusion: Bone marrow stimulation causes bony compression that may negatively impact subchondral bone and trabecular alignment. It is important to understand which tools used for bone marrow stimulation cause the least amount of damage to the subchondral bone. Clinical Relevance: This study demonstrates the decreased subchondral bony defects seen with the microdrill versus the traditional microfracture awl indicating that when performing bone marrow stimulation, the microdrill may be a less harmful tool to the subchondral bone.

Exposure of Tissue-Engineered Cartilage Analogs to Synovial Fluid Hematoma After Ankle Fracture Is Associated With Chondrocyte Death and Altered Cartilage Maintenance Gene Expression.

BACKGROUND: The first stage of fracture healing consists of hematoma formation with recruitment of proinflammatory cytokines and matrix metalloproteinases. Unfortunately, when there is an intra-articular fracture, these inflammatory mediators are not retained at the fracture site, but instead, envelop the healthy cartilage of the entire joint via the synovial fluid fracture hematoma (SFFH). These inflammatory cytokines and matrix metalloproteinases are known factors in the progression of osteoarthritis and rheumatoid arthritis. Despite the known inflammatory contents of the SFFH, little research has been done on the effects of the SFFH on healthy cartilage with regard to cell death and alteration in gene expression that could lead to posttraumatic osteoarthritis (PTOA). METHODS: SFFH was collected from 12 patients with intraarticular ankle fracture at the time of surgery. Separately, C20A4 immortalized human chondrocytes were 3-dimensionally cultured to create scaffold-free cartilage tissue analogs (CTAs) to simulate healthy cartilage. Experimental CTAs (n = 12) were exposed to 100% SFFH for 3 days, washed, and transferred to complete media for 3 days. Control CTAs (n = 12) were simultaneously cultured in complete medium without exposure to SFFH. Subsequently, CTAs were harvested and underwent biochemical, histological, and gene expression analysis. RESULTS: Exposure of CTAs to ankle SFFH for 3 days significantly decreased chondrocyte viability by 34% (P = .027). Gene expression of both COL2A1 and SOX9 were significantly decreased after exposure to SFFH (P = .012 and P = .0013 respectively), while there was no difference in COL1A1, RUNX2, and MMP13 gene expression. Quantitative analysis of Picrosirius red staining demonstrated increased collagen I deposition with poor ultrastructural organization in SFFH-exposed CTAs. CONCLUSION: Exposure of an organoid model of healthy cartilage tissue to SFFH after intraarticular ankle fracture resulted in decreased chondrocyte viability, decreased expression of genes regulating normal chondrocyte phenotype, and altered matrix ultrastructure indicating differentiation toward an osteoarthritis phenotype. CLINICAL RELEVANCE: The majority of ankle fracture open reduction and internal fixation does not occur immediately after fracture. In fact, typically these fractures are treated several days to weeks later in order to let the swelling subside. This means that the healthy innocent bystander cartilage not involved in the fracture is exposed to SFFH during this time. In this study, the SFFH caused decreased chondrocyte viability and specific altered gene expression that might have the potential to induce osteoarthritis. These data suggest that early intervention after intraarticular ankle fracture could possibly mitigate progression toward PTOA.

Tumor necrosis is an underappreciated histopathologic factor in the grading of chondrosarcoma.

BACKGROUND: Cartilaginous neoplasms can be challenging to grade; there is a need to create an evidence-based rubric for grading. The goal of this study was to identify histopathologic features of chondrosarcoma that were associated with 5-year survival and to compare these to traditional patient, tumor and treatment variables. METHODS: This was a retrospective review of all patients undergoing surgical resection of a primary chondrosarcoma with at least 2 years of follow up. All specimens were independently reviewed by two pathologists and histopathologic features scored. Univariate and multivariate analyses were performed utilizing Kaplan Meier and proportional hazards methods to identify variables associated with 5-year disease specific survival (DSS) and disease free survival (DFS). RESULTS: We identified 51 patients with an average follow up of 49 months eligible for inclusion. 30% of tumors were low grade, 45% were intermediate grade, and 25% were high grade. In a univariate analysis considering histopathologic factors, higher tumor mitotic rate (HR 8.9, p < 0.001), tumor dedifferentiation (HR 7.3, p < 0.001), increased tumor cellularity (HR 5.8, p = 0.001), increased tumor atypia (HR 5.8, p = 0.001), LVI (HR 4.7, p = 0.04) and higher tumor necrosis (HR 3.7, p = 0.02) were all associated with worse 5-year DSS. In a multivariate analysis controlling for potentially confounding variables, higher tumor necrosis was significantly associated with disease specific survival survival (HR 3.58, p = 0.035); none of the factors were associated with DFS. CONCLUSIONS: This study provides an evidence-based means for considering histopathologic markers and their association with prognosis in chondrosarcoma. Our findings suggest that necrosis and LVI warrant further study.

Regional anesthesia is associated with improved metastasis free survival after surgical resection of bone sarcomas.

There is increasing evidence that perioperative factors, including type of anesthesia, may be an important consideration regarding oncological disease progression. Previous studies have suggested that regional anesthesia can improve oncological outcomes by reducing the surgical stress response that occurs during tumor resection surgery and that may promote metastatic progression. The purpose of this study is to provide the first robust investigation of the impact of adding regional anesthesia to general anesthesia on oncological outcomes following sarcoma resection. One hundred patients with bone sarcoma were retrospectively analyzed in this study. After adjusting for confounding variables such as age and grade of the tumor, patients with bone sarcoma receiving regional anesthesia in addition to general anesthesia during resection had improved metastasis free survival (multivariate hazard ratio of 0.47 and p = 0.034). Future studies are needed to confer the beneficial effect of regional anesthesia, and to further investigate the potential mechanism. Clinical significance: The results from this study provide evidence that regional anesthesia may be advantageous in the setting of bone sarcoma resection surgery, reducing pain while also improving oncological outcomes and should be considered when clinically appropriate.

The efficacy of platelet-rich plasma in osseous foot and ankle pathology: a review.

The purpose of this review is to develop evidence-based practices for the use of platelet-rich plasma (PRP) to treat osseous pathologies of the lower extremity. There is moderate high-quality evidence to support the efficacy of PRP as a surgical augment to microfracture in osteochondral lesions of the talus (OLT). The literature supports a conceivable positive impact on bony union and osseous healing. There is insufficient evidence to support PRP injections in the conservative management of OLT or symptomatic ankle osteoarthritis. PRP may serve as a viable treatment method in the surgical augmentation of microfracture surgery in OLT and has promise for increasing bony union following surgical operations. Further high-quality, comparative studies with longer clinical follow-up are required.

The purpose of this review is to develop evidence-based practices for the use of platelet-rich plasma (PRP) to treat bony pathologies of the lower extremity. There is moderate high-quality evidence to support the use of PRP in surgery to treat damage of both cartilage and bone in the foot. The literature supports a conceivable positive impact on bony healing after fracture. There is insufficient evidence to support PRP injections in the conservative management symptomatic ankle osteoarthritis. PRP may augment bone stimulation surgery in cases of cartilage and bone defects with promise for increasing bone to bone healing following surgical operations. Further high-quality, comparative studies with longer clinical follow-up are required.

Does a fibula-sparing approach improve outcomes in tibiotalocalcaneal arthrodesis?

BACKGROUND: Tibiotalocalcaneal (TTC) arthrodesis is considered a salvage procedure for either complex deformity or arthritis about the hindfoot, and can be performed via fibula-resection (FR) or fibula-sparing (FS) approaches. The primary aim of this study was to investigate differences in outcomes in FR versus FS TTC arthrodeses. METHODS: This was a retrospective cohort study reviewing outcomes of TTC arthrodesis at a single institution. Patients who underwent a TTC arthrodesis from 2005 to 2017 and had minimum two-year follow-up were included. Preoperative diagnosis, pre- and post-operative radiographic coronal alignment, fixation methods, and complications were compared between groups. RESULTS: 107 patients (110 ankles) underwent TTC arthrodesis, with a mean age of 57.0 years (sd, 14.0 years). The mean clinical follow-up was 50.7 months (range, 24-146) and mean radiographic follow-up was 45.8 months (range, 6-146 months). Pre-operative diagnoses included arthritis (N = 40), prior non-union (N = 21), Charcot neuro-arthropathy (N = 15), failed total ankle arthroplasty (N = 15) and avascular necrosis of the talus (N = 19). Sixty-nine ankles comprised the FS group and 41 comprised the FR group. There was no significant difference in the non-union rate between groups (29% FR vs 38% FS, p = 0.37), complication rate (59% FR vs 64% FS, p = 0.59), or post-operative coronal standing radiographic alignment (89.6 degrees FR, 90.5 degrees FS, p = 0.26). Logistic regression analyses demonstrated a pre-operative diagnosis of failed TAA was associated with post-operative nonunion (OR:3.41,CI:1.13-11.04,p = 0.03). Pre-operative indication for TTC arthrodesis of arthritis alone was associated with a decreased risk of non-union (OR:0.27,CI:0.11-0.62,p = 0.002). CONCLUSION: TTC arthrodesis is a successful surgical option for complex hindfoot deformity, arthritis, and limb salvage regardless of surgical approach. We did not detect a difference in the union rate, incidence of complications, or coronal plane radiographic alignment in fibula-sparing versus fibula-resection constructs. Patients with a pre-operative indication for surgery of arthritis may be at decreased risk of developing non-union. LEVEL OF EVIDENCE: III - Retrospective cohort study.

Efficacy of Platelet-Rich Plasma in Soft Tissue Foot and Ankle Pathology.

➢: The preparation methodology for platelet-rich plasma (PRP) may have important clinical implications with varying effectiveness with leukocyte, platelet, and growth factor concentrations. ➢: There is high-quality evidence to support the superiority of PRP over corticosteroids in the case of chronic plantar fasciitis. ➢: There is moderate-quality to high-quality evidence for PRP's ability to increase tendon thickness with no capacity to decrease pain, increase function, or augment percutaneous tenotomy in Achilles tendinopathy. ➢: There is insufficient evidence to support PRP injections in the definitive treatment of Achilles tendon rupture. However, PRP may contribute to postoperative recovery after tendon rupture repair, but this requires further research. ➢: The biochemical theory supporting the clinical use of PRP must be reinforced with high-level evidence research. Based on the current literature, PRP may serve as a viable treatment method in chronic plantar fasciitis. Further high-quality, comparative studies with longer clinical follow-up are required to support recommendations for use of PRP in the treatment of Achilles tendon pathology.

Outcomes of Surgical Reconstruction Using Custom 3D-Printed Porous Titanium Implants for Critical-Sized Bone Defects of the Foot and Ankle.

BACKGROUND: Treating critically sized defects (CSDs) of bone remains a significant challenge in foot and ankle surgery. Custom 3D-printed implants are being offered to a small but growing subset of patients as a salvage procedure in lieu of traditional alternates such as structural allografts after the patient has failed prior procedures. The long-term outcomes of 3D-printed implants are still unknown and understudied because of the limited number of cases and short follow-up durations. The purpose of this study was to evaluate the outcomes of patients who received custom 3D-printed implants to treat CSDs of the foot and ankle in an attempt to aid surgeons in selecting appropriate surgical candidates. METHODS: This was a retrospective study to assess surgical outcomes of patients who underwent implantation of a custom 3D-printed implant made with medical-grade titanium alloy powder (Ti-6Al-4V) to treat CSDs of the foot and ankle between June 1, 2014, and September 30, 2019. All patients had failed previous nonoperative or operative management before proceeding with treatment with a custom 3D-printed implant. Univariate and multivariate odds ratios (ORs) of a secondary surgery and implant removal were calculated for perioperative variables. RESULTS: There were 39 cases of patients who received a custom 3D-printed implant with at least 1 year of follow-up. The mean follow-up time was 27.0 (12-74) months. Thirteen of 39 cases (33.3%) required a secondary surgery and 10 of 39 (25.6%) required removal of the implant because of septic nonunion (6/10) or aseptic nonunion (4/10). The mean time to secondary surgery was 10 months (1-22). Multivariate logistic regression revealed that patients with neuropathy were more likely to require a secondary surgery with an OR of 5.76 (P = .03). CONCLUSION: This study demonstrated that 74% of patients who received a custom 3D-printed implant for CSDs did not require as subsequent surgery (minimum of 1-year follow-up). Neuropathy was significantly associated with the need for a secondary surgery. This is the largest series to date demonstrating the efficacy of 3D-printed custom titanium implants. As the number of cases using patient-specific 3D-printed titanium implant increases, larger cohorts of patients should be studied to identify other high-risk groups and possible interventions to improve surgical outcomes. LEVEL OF EVIDENCE: Level IV, case series.

Intra-Articular Synovial Fluid With Hematoma After Ankle Fracture Promotes Cartilage Damage In Vitro Partially Attenuated by Anti-Inflammatory Agents.

BACKGROUND: Intra-articular ankle fracture (IAF) causes posttraumatic osteoarthritis (PTOA), but the exact mechanism is unknown. Proinflammatory mediators have been shown to be present in the synovial fluid fracture hematoma (SFFH) but have not been linked to cartilage damage. The purpose of this study was to determine if the SFFH causes cartilage damage and whether this damage can be attenuated by commercially available therapeutic agents. METHODS: Synovial fluid was obtained from 54 IAFs and cultured with cartilage discs from the dome of fresh allograft human tali and randomly assigned to one of the following groups: (A) control-media only, (B) SFFH from days 0 to 2 after fracture, (C) SFFH from days 3 to 9, (D) SFFH from days 10 to 14, (E) group B + interleukin 1 receptor antagonist (IL-1Ra), and (F) group B + doxycycline. The cartilage discs underwent histological evaluation for cell survival and cartilage matrix components. The spent media were analyzed for inflammatory mediators. RESULTS: Cartilage discs cultured with SFFH in groups B, C, and D demonstrated significantly increased production of cytokines, metalloproteinases (MMPs), and extracellular matrix breakdown products. Safranin O staining was significantly decreased in group B. The negative effects on cartilage were partially attenuated with the addition of either IL-1RA or doxycycline. There was no difference in chondrocyte survival among the groups. CONCLUSION: Exposure of uninjured cartilage to IAF SFFH caused activation of cartilage damage pathways evident through cartilage disc secretion of inflammatory cytokines, MMPs, and cartilage matrix fragments. The addition of IL-1Ra or doxycycline to SFFH culture partially attenuated this response. CLINICAL RELEVANCE: IAFs create an adverse intra-articular environment consisting of significantly increased levels of inflammatory cytokines and MMPs able to damage cartilage throughout the joint. These data suggest that the acute addition of specific inflammatory inhibitors may decrease the levels of these proinflammatory mediators.

Effect of surface topography on in vitro osteoblast function and mechanical performance of 3D printed titanium.

Critical-sized defects remain a significant challenge in orthopaedics. 3D printed scaffolds are a promising treatment but are still limited due to inconsistent osseous integration. The goal of the study is to understand how changing the surface roughness of 3D printed titanium either by surface treatment or artificially printing rough topography impacts the mechanical and biological properties of 3D printed titanium. Titanium tensile samples and discs were printed via laser powder bed fusion. Roughness was manipulated by post-processing printed samples or by directly printing rough features. Experimental groups in order of increasing surface roughness were Polished, Blasted, As Built, Sprouts, and Rough Sprouts. Tensile behavior of samples showed reduced strength with increasing surface roughness. MC3T3 pre-osteoblasts were seeded on discs and analyzed for cellular proliferation, differentiation, and matrix deposition at 0, 2, and 4 weeks. Printing roughness diminished mechanical properties such as tensile strength and ductility without clear benefit to cell growth. Roughness features were printed on mesoscale, unlike samples in literature in which roughness on microscale demonstrated an increase in cell activity. The data suggest that printing artificial roughness on titanium scaffold is not an effective strategy to promote osseous integration.

3D printing of high-strength, porous, elastomeric structures to promote tissue integration of implants.

Despite advances in biomaterials research, there is no ideal device for replacing weight-bearing soft tissues like menisci or intervertebral discs due to poor integration with tissues and mechanical property mismatch. Designing an implant with a soft and porous tissue-contacting structure using a material conducive to cell attachment and growth could potentially address these limitations. Polycarbonate urethane (PCU) is a soft and tough biocompatible material that can be 3D printed into porous structures with controlled pore sizes. Porous biomaterials of appropriate chemistries can support cell proliferation and tissue ingrowth, but their optimal design parameters remain unclear. To investigate this, porous PCU structures were 3D-printed in a crosshatch pattern with a range of in-plane pore sizes (0 to 800 µm) forming fully interconnected porous networks. Printed porous structures had ultimate tensile strengths ranging from 1.9 to 11.6 MPa, strains to failure ranging from 300 to 486%, Young's moduli ranging from 0.85 to 12.42 MPa, and porosity ranging from 13 to 71%. These porous networks can be loaded with hydrogels, such as collagen gels, to provide additional biological support for cells. Bare PCU structures and collagen-hydrogel-filled porous PCU support robust NIH/3T3 fibroblast cell line proliferation over 14 days for all pore sizes. Results highlight PCU's potential in the development of tissue-integrating medical implants.

Evaluation of Vessel Sealing Performance Among Ultrasonic Devices in a Porcine Model.

BACKGROUND: As new technologies emerge, it is imperative to define which new devices are most likely to provide a reproducible, effective result for the patient and surgeon. The purpose of our study was to analyze 3 commercially available ultrasonic energy devices; the Sonicision (SC), the Harmonic ACE (HA), and the THUNDERBEAT (TB). MATERIAL AND METHODS: Eight female Yorkshire pigs were used for data collection and vessel harvest. Three devices were evaluated and compared with each other with respect to seal failure and cutting speed in vivo. After vessel harvest, one end of the fragment was sent for histological evaluation, and the other was used for burst pressure measurement testing in a blinded fashion. The coagulation and cut levels of all the generators were set up at a similar and constant level. RESULTS: Eighty-four vessels (47 arteries and 37 veins) were tested. Mean vessel diameter was equal among the groups. Cutting speed was significantly faster with TB (3.4 ± 0.7 seconds) than SC or HA (5.8 ± 2.4 and 6.1 ± 3.1 seconds; P < .0001). Burst pressure trended higher after ligation with TB (505.4 ± 349.4 mm Hg) than SC and HA (435.8 ± 403.0 and 437.6 ± 291.3 mm Hg). There were 2 seal failures in the SC group and HA group and none in the TB group. Histologically, the perpendicular width of tissue seal with TB (1.250 ± 0.55 mm) was significantly longer than that of the SC and the HA (0.772 ± 0.23 and 0.686 ± 0.23 mm; P < .0001). CONCLUSIONS: TB has proven to provide the most rapid and reliable seal. Therefore, TB may be safer and may decrease time during surgical procedures.