Optimized Decellularization of a Porcine Fasciocutaneaous Flap.

Reconstructive techniques to repair severe tissue defects include the use of autologous fasciocutaneous flaps, which may be limited due to donor site availability or lead to complications such as donor site morbidity. A number of synthetic or natural dermal substitutes are in use clinically, but none have the architectural complexity needed to reconstruct deep tissue defects. The perfusion decellularization of fasciocutaneous flaps is an emerging technique that yields a scaffold with the necessary composition and vascular microarchitecture and serves as an alternative to autologous flaps. In this study, we show the perfusion decellularization of porcine fasciocutaneous flaps using sodium dodecyl sulfate (SDS) at three different concentrations, and identify that 0.2% SDS results in a decellularized flap that is efficiently cleared of its cellular material at 86%, has maintained its collagen and glycosaminoglycan content, and preserved its microvasculature architecture. We further demonstrate that the decellularized graft has the porous structure and growth factors that would facilitate repopulation with cells. Finally, we show the biocompatibility of the decellularized flap using human dermal fibroblasts, with cells migrating as deep as 150 µm into the tissue over a 7-day culture period. Overall, our results demonstrate the promise of decellularized porcine flaps as an interesting alternative for reconstructing complex soft tissue defects, circumventing the limitations of autologous skin flaps.

Effect of Donor Age and Liver Steatosis on Potential of Decellularized Liver Matrices to be used as a Platform for iPSC-Hepatocyte Culture.

Decellularization of discarded whole livers and their recellularization with patient-specific induced pluripotent stem cells (iPSCs) to develop a functional organ is a promising approach to increasing the donor pool. The effect of extracellular matrix (ECM) of marginal livers on iPSC-hepatocyte differentiation and function has not been shown. To test the effect of donor liver ECM age and steatosis, young and old, as well as no, low, and high steatosis livers, are decellularized. All livers are decellularized successfully. High steatosis livers have fat remaining on the ECM after decellularization. Old donor liver ECM induces lower marker expression in early differentiation stages, compared to young liver ECM, while this difference is closed at later stages and do not affect iPSC-hepatocyte function significantly. High steatosis levels of liver ECM lead to higher albumin mRNA expression and secretion while at later stages of differentiation expression of major cytochrome (CYP) 450 enzymes is highest in low steatosis liver ECM. Both primary human hepatocytes and iPSC-hepatocytes show an increase in fat metabolism marker expression with increasing steatosis levels most likely induced by excess fat remaining on the ECM. Overall, removal of excess fat from liver ECM may be needed for inducing proper hepatic function after recellularization.

Prevalence of Paget's disease of bone: review of consecutive abdominopelvic CT scans and literature.

BACKGROUND: Previous studies suggest an overall decrease of Paget's disease of bone (PDB) prevalence. However, a large number of asymptomatic patients make previously reported prevalence likely underrepresented. PURPOSE: To evaluate the prevalence of PDB in our patient population. MATERIAL AND METHODS: We retrospectively identified 1295 (mean age = 59 years; age range = 18-98 years) consecutive abdominopelvic computed tomography (CT) scans over a 15-day period in 2014. Abdominopelvic CT images were reviewed to assess for the presence of PDB in the lower thoracic spine, lumbar spine, pelvis, or proximal femora. This prevalence was compared with prevalence reported in earlier literature using Fisher's exact test. RESULTS: Of the included patients, 5/1295 (0.39%) patients had imaging findings of PDB on abdominopelvic CT. Those five patients were all aged ≥55 years and had pelvic bone involvement, with one patient having additional involvement of multiple lower thoracic vertebral bodies. In our studied cohort, 812/1295 (62.7%) patients were aged ≥55 years, which corresponds to a prevalence of 0.62% (5/812) of PDB in patients aged ≥55 years. When accounting for fact that bones of the pelvis are involved in 40%-91% of patients with PDB, the prevalence is estimated at 0.43%-0.98% in the total adult population and estimated at 0.68%-1.55% in older adults. The prevalence was greater than two studies before 1960, and less than some studies during 1960-2019. CONCLUSION: We found that the prevalence of PDB on abdominopelvic CTs was 0.39% of all adult patients with an increase after the age of 55 years.

Acellular Nipple Scaffold Development, Characterization, and Preliminary Biocompatibility Assessment in a Swine Model.

BACKGROUND: The standard in nipple reconstruction remains the autologous skin flap. Unfortunately, the results are not satisfying, with up to 75% loss of nipple projection over time. Existing studies investigated the use of primates as a source of implants. The authors hypothesized that the porcine nipple can serve as a perfect shape-supporting implant because of functional similarities to the human nipple. A decellularization protocol was developed to obtain an acellular nipple scaffold (ANS) for nipple reconstruction. METHODS: Tissue samples were collected from eight disease-free female Yorkshire pigs (60 to 70 kg) and then decellularized. The decellularization efficiency and extracellular matrix characterization was performed histologically and quantitatively (DNA, total collagen, elastin, and glycosaminoglycan content). In vitro and in vivo biocompatibility was determined by human dermal fibroblast culture and subcutaneous implantation of six ANSs in a single Yorkshire pig (60 to 70 kg), respectively. Inflammation and adverse events were monitored daily based on local clinical signs. RESULTS: The authors showed that all cellular structures and 96% of DNA [321.7 ± 57.6 ng DNA/mg wet tissue versus 11.7 ± 10.9 ng DNA/mg wet tissue, in native and ANS, respectively ( P < 0.001)] can be successfully removed. However, this was associated with a decrease in collagen [89.0 ± 11.4 and 58.8 ± 9.6 µg collagen/mg ( P < 0.001)] and elastin [14.2 ± 1.6 and 7.9 ± 2.4 µg elastin/mg ( P < 0.05)] and an increase in glycosaminoglycan content [5.0 ± 0.7 and 6.0 ± 0.8 ng/mg ( P < 0.05)]. ANS can support continuous cell growth in vitro and during preliminary biocompatibility tests in vivo. CONCLUSION: This is a preliminary report of a novel promising ANS for nipple reconstruction, but more research is needed to validate results. CLINICAL RELEVANCE STATEMENT: Breast cancer is very common among women. Treatment involves mastectomy, but its consequences affect patient mental well-being, and can lead to depression. Nipple-areola complex reconstruction is critical, and existing methods lead to unsatisfactory outcomes.

Human-Origin iPSC-Based Recellularization of Decellularized Whole Rat Livers.

End-stage liver diseases lead to mortality of millions of patients, as the only treatment available is liver transplantation and donor scarcity means that patients have to wait long periods before receiving a new liver. In order to minimize donor organ scarcity, a promising bioengineering approach is to decellularize livers that do not qualify for transplantation. Through decellularization, these organs can be used as scaffolds for developing new functional organs. In this process, the original cells of the organ are removed and ideally should be replaced by patient-specific cells to eliminate the risk of immune rejection. Induced pluripotent stem cells (iPSCs) are ideal candidates for developing patient-specific organs, yet the maturity and functionality of iPSC-derived cells do not match those of primary cells. In this study, we introduced iPSCs into decellularized rat liver scaffolds prior to the start of differentiation into hepatic lineages to maximize the exposure of iPSCs to native liver matrices. Through exposure to the unique composition and native 3D organization of the liver microenvironment, as well as the more efficient perfusion culture throughout the differentiation process, iPSC differentiation into hepatocyte-like cells was enhanced. The resulting cells showed significantly higher expression of mature hepatocyte markers, including important CYP450 enzymes, along with lower expression of fetal markers, such as AFP. Importantly, the gene expression profile throughout the different stages of differentiation was more similar to native development. Our study shows that the native 3D liver microenvironment has a pivotal role to play in the development of human-origin hepatocyte-like cells with more mature characteristics.

Posterior Tibial Slope Increases Anterior Cruciate Ligament Stress in Bi-Cruciate Retaining Total Knee Arthroplasty: In Vivo Kinematic Analysis.

The study design involved here is experimental in nature. The resection of the anterior cruciate ligament (ACL) during conventional total knee arthroplasty (TKA) has been considered a potential factor leading to abnormal in vivo knee kinematics. Bi-cruciate retaining (BCR) TKA designs allow the preservation of the ACL with the potential to restore native knee kinematics. This study aimed to investigate the effect of posterior tibial slope (PTS) on stress experienced by the ACL during weight bearing sit-to-stand (STS) and single-leg deep lunge. The ACL elongation patterns were measured in 30 unilateral BCR TKA patients during weight-bearing STS and single-leg deep lunge using a validated dual fluoroscopic tracking technique. The minimum normalized stress within the anteromedial (AM) and posterolateral (PL) bundle of the ACL during weight-bearing STS and single-leg deep lunge was found at a PTS of 3.7 degrees. The maximum AM and PL bundle stresses were observed at a PTS of 8.5 and 9.3 degrees, respectively during STS and at 8.4, and 9.1 degrees, respectively during single-leg deep lunge. There was a significant positive correlation between PTS and stress observed within the AM and PL bundle of the ACL during weight-bearing STS (R 2 = 0.37; p < 0.01; R2 = 0.36; p = 0.01) and single-leg deep lunge (R 2 = 0.42; p < 0.01; R 2 = 0.40; p < 0.01). The study demonstrates that PTS of operated BCR TKA knees has a significant impact on the stress experienced by the preserved ACL during weight-bearing STS and single-leg deep lunge. This suggests that avoiding excessive PTS may be one of the surgical implant alignment factors to consider during surgery to minimize increased loading of the preserved ACL.

Gait and Knee Flexion In Vivo Kinematics of Asymmetric Tibial Polyethylene Geometry Cruciate Retaining Total Knee Arthroplasty.

The preservation of the posterior cruciate ligament in cruciate retaining (CR) total knee arthroplasty (TKA) designs has the potential to restore healthy knee biomechanics; however, concerns related to kinematic asymmetries during functional activities still exist in unilateral TKA patients. As there is a limited data available regarding the ability of the contemporary CR TKA design with concave medial and convex lateral tibial polyethylene bearing components to restore healthy knee biomechanics, this study aimed to investigate in vivo three-dimensional knee kinematics in CR TKA patients during strenuous knee flexion activities and gait. Using a combined computer tomography and dual fluoroscopic imaging system approach, in vivo kinematics of 15 unilateral CR TKA patients (comparison of replaced and contralateral nonreplaced knee) were evaluated during sit-to-stand, step-ups, single-leg deep lunge, and level walking. The patient cohort was followed-up at an average of 24.5 months ( ± 12.6, range 13-42) from surgical procedure. Significantly smaller internal knee rotation angles were observed for the contemporary CR TKA design during step-ups (2.6 ± 5.8 vs. 6.3 ± 6.6 degrees, p < 0.05) and gait (0.6 ± 4.6 vs. 6.3 ± 6.8 degrees, p < 0.05). Significantly larger proximal and anterior femoral translations were measured during sit-to-stand (34.7 ± 4.5 vs. 29.9 ± 3.1 mm, p < 0.05; -2.5 ± 2.9 vs. -8.1 ± 4.4 mm, p < 0.05) and step-ups (34.1 ± 4.5 vs. 30.8 ± 2.9 mm, p < 0.05; 2.2 ± 3.2 vs. -3.5 ± 4.5 mm, p < 0.05). Significantly smaller ranges of varus/valgus and internal/external rotation range of motion were observed for CR TKA, when compared with the nonoperated nee, during strenuous activities and gait. The preservation of the posterior cruciate ligament in the contemporary asymmetric bearing geometry CR TKA design with concave medial and convex lateral tibial polyethylene bearing components has the potential to restore healthy knee biomechanics; however, the study findings demonstrate that native knee kinematics were not fully restored in patients with unilateral asymmetric tibial polyethylene bearing geometry CR TKA during functional activities.

Knee Arthroscopy Prior to Revision TKA Is Associated with Increased Re-Revision for Stiffness.

This is an experimental study. As knee arthroscopy may be used as a suitable temporizing alternative prior to revision surgery, knee arthroscopy potentially may be a risk factor for subsequent adverse outcomes after revision total knee arthroplasty (TKA). This study aimed to evaluate the impact of prior knee arthroscopy on outcomes of subsequent TKA revision surgery. We identified 1,689 consecutive patients who underwent revision TKA: (1) patients with no prior knee arthroscopy (n = 1,549) and (2) patients with knee arthroscopy prior to revision TKA (n = 140). A control group of matched revision TKA patients who did not undergo prior knee arthroscopy was identified (700 patients), using one-to-five matching. Matched patients with prior knee arthroscopy demonstrated an increased likelihood of requiring re-revision (odds ratio [OR], 2.06, p < 0.001), particularly for stiffness (OR, 2.72, p < 0.02) compared with patients who underwent revision TKA without prior knee arthroscopy. Knee arthroscopy demonstrated a time-dependent impact on revision TKA outcomes, with an increased likelihood of requiring re-revision for patients who underwent knee arthroscopy within 6 months prior to revision TKA compared with patients who underwent knee arthroscopy within 6 to 12 months prior to revision TKA (OR, 3.16, p < 0.04). This cohort matched study shows that patients who had prior knee arthroscopy demonstrated a significantly higher likelihood of requiring re-revision compared with patients who underwent revision TKA without prior knee arthroscopy. Additionally, there was a significant increased likelihood in requiring re-revision for patients who had prior knee arthroscopy within 6 months. This provides clinically useful information for counseling of patients who are considering temporizing their symptoms with knee arthroscopy prior to revision TKA.

Engineering Vascularized Composite Allografts Using Natural Scaffolds: A Systematic Review.

Vascularized composite allotransplantation (VCA) refers to the transplantation of multiple tissues as a functional unit from a deceased donor to a recipient with a severe injury. These grafts serve as potential replacements for traumatic tissue losses. The main problems are the consequences of the long immunosuppressive drugs and the lack of compatible donor. To avoid these limitations, decellularization/recellularization constitutes an attractive approach. The aim of decellularization/recellularization technology is to develop immunogenic free biological substitutes that will restore, maintain, or improve tissue and organ's function. A PubMed search was performed for articles on decellularization and recellularization of composite tissue allografts between February and March 2021, with no restrictions in publication year. The selected reports were evaluated in terms of decellularization protocols, assessment of decellularized grafts, and evaluation of their biocompatibility and repopulation with cells both in vitro and in vivo. The search resulted in a total of 88 articles. Each article was reviewed, 77 were excluded, and the remaining 11 articles reported decellularization of 12 different vascular composite allografts in humans (4), large animals (3), and small animals (rodents; 5). The decellularization protocol for VCA varies slightly between studies, but majority of the reports employ 1% sodium dodecyl sulfate as the main reagent for decellularization. The immunological response of the decellularized scaffolds remain poorly evaluated. Few authors have been able to attempt the recellularization and transplantation of these scaffolds. Successful transplantation seems to require prior recellularization. Decellularization/recellularization is a promising, growing, and emerging developing research field in vascular composite allotransplantation. Impact statement Tissue engineering for vascular composite allotransplantation using decellularization and recellularization approach is a fast-growing area of interest in the reconstructive surgery field. This review will be a very useful tool to get a clear overview for researchers interested in this field.

Liver donor age affects hepatocyte function through age-dependent changes in decellularized liver matrix.

The only treatment available for end stage liver diseases is orthotopic liver transplantation. Although there is a big donor scarcity, many donor livers are discarded as they do not qualify for transplantation. Alternatively, decellularization of discarded livers can potentially render them transplantable upon recellularization and functional testing. The success of this approach will heavily depend on the quality of decellularized scaffolds which might show variability due to factors including age. Here we assessed the age-dependent differences in liver extracellular matrix (ECM) using rat and human livers. We show that the liver matrix has higher collagen and glycosaminoglycan content and a lower growth factor content with age. Importantly, these changes lead to deterioration in primary hepatocyte function potentially due to ECM stiffening and integrin-dependent signal transduction. Overall, we show that ECM changes with age and these changes significantly affect cell function thus donor age should be considered as an important factor for bioengineering liver substitutes.

One-stage revision is as effective as two-stage revision for chronic culture-negative periprosthetic joint infection after total hip and knee arthroplasty.

AIMS: Removal of infected components and culture-directed antibiotics are important for the successful treatment of chronic periprosthetic joint infection (PJI). However, as many as 27% of chronic PJI patients yield negative culture results. Although culture negativity has been thought of as a contraindication to one-stage revision, data supporting this assertion are limited. The aim of our study was to report on the clinical outcomes for one-stage and two-stage exchange arthroplasty performed in patients with chronic culture-negative PJI. METHODS: A total of 105 consecutive patients who underwent revision arthroplasty for chronic culture-negative PJI were retrospectively evaluated. One-stage revision arthroplasty was performed in 30 patients, while 75 patients underwent two-stage exchange, with a minimum of one year's follow-up. Reinfection, re-revision for septic and aseptic reasons, amputation, readmission, mortality, and length of stay were compared between the two treatment strategies. RESULTS: The patient demographic characteristics did not differ significantly between the groups. At a mean follow-up of 4.2 years, the treatment failure for reinfection for one-stage and two-stage revision was five (16.7%) and 15 patients (20.0%) (p = 0.691), and for septic re-revision was four (13.3%) and 11 patients (14.7%) (p = 0.863), respectively. No significant differences were observed between one-stage and two-stage revision for 30- 60- and 90-day readmissions (10.0% vs 8.0%; p = 0.714; 16.7% vs 9.3%; p = 0.325; and 26.7% vs 10.7%; p = 0.074), one-year mortality (3.3% vs 4.0%; p > 0.999), and amputation (3.3% vs 1.3%; p = 0.496). CONCLUSION: In this non-randomized study, one-stage revision arthroplasty demonstrated similar outcomes including reinfection, re-revision, and readmission rates for the treatment of chronic culture-negative PJI after TKA and THA compared to two-stage revision. This suggests culture negativity may not be a contraindication to one-stage revision arthroplasty for chronic culture-negative PJI in selected patients. Cite this article: Bone Joint J 2021;103-B(3):515-521.

Single-Stage Revision of the Infected Total Knee Arthroplasty Is Associated With Improved Functional Outcomes: A Propensity Score-Matched Cohort Study.

BACKGROUND: Single-stage revision is an alternative to the standard 2-stage revision, potentially minimizing morbidities and improving functional outcomes. This study aimed at comparing single-stage and 2-stage revision total knee arthroplasty (TKA) for chronic periprosthetic joint infection (PJI) with regard to patient-reported outcome measures (PROMs) and complication rates. METHODS: A total of 185 consecutive revision TKA patients for chronic PJI with complete preoperative and postoperative PROMs were investigated. A total of 44 patients with single-stage revision TKA were matched to 88 patients following 2-stage revision TKA using propensity score matching, yielding a total of 132 propensity score-matched patients for analysis. Patient demographics and clinical information including reinfection and readmission rates were evaluated. RESULTS: There was no significant difference in preoperative PROMs between propensity score-matched single-stage and 2-stage revision TKA cohorts. Postoperatively, significantly higher PROMs for single-stage revision TKA were observed for Knee disability and Osteoarthritis Outcome Score physical function (62.2 vs 51.9, P < .01), physical function short form 10A (42.8 vs 38.1, P < .01), PROMIS SF Physical (44.8 vs 41.0, P = .01), and PROMIS SF Mental (50.5 vs 47.1, P = .02). There was no difference between propensity score-matched single-stage and 2-stage revision TKA cohorts for clinical outcomes including reinfection rates (25.0% vs 27.2%, P = .78) and 90-day readmission rates (22.7% vs 25.0%, P = .77). CONCLUSION: This study illustrated that single-stage revision TKA for chronic PJI may be associated with superior patient-reported outcomes compared to 2-stage revision for the infected TKA using a variety of PROMs. Improved PROMs were not accompanied by differences in complication rates between both cohorts, suggesting that single-stage revision TKA may provide an effective alternative to 2-stage revision in patients with chronic TKA PJI.

Sensitivity and Specificity of Serum and Synovial Fluid Markers in Diagnosis of Infection in Head-Neck Taper Corrosion of Metal-On-Polyethylene Total Hip Arthroplasty.

BACKGROUND: The accurate diagnosis of periprosthetic joint infection (PJI) in the setting of adverse local tissue reactions in patients with metal-on-polyethylene (MoP) total hip arthroplasty (THA) secondary to head-neck taper junction corrosion is challenging as it frequently has the appearance of purulence. The aim of this study is to evaluate the utility of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and synovial fluid markers in diagnosing PJI in failed MoP THA due to head-neck taper corrosion. METHODS: A total of 89 consecutive patients with MoP THA with head-neck taper corrosion in 2 groups was evaluated: (1) infection group (n = 11) and (2) noninfection group (n = 78). All patients had highly crossed polyethylene with cobalt chromium femoral heads and had preoperative synovial fluid aspiration. In addition, serum cobalt and chromium levels were analyzed. RESULTS: The optimal cutoff value for synovial white blood cell was 2144 with 93% sensitivity and 84% specificity. Neutrophil count optimal cutoff value was 82% with 93% sensitivity and 82% specificity. Receiver operating characteristic analysis of ESR and CRP determined optimal cutoff at 57 mm/h and 35 mg/L with 57% sensitivity and 94% specificity and 93% sensitivity and 76% specificity, respectively. There were no significant differences in metal ion levels between the infected and noninfected groups. CONCLUSION: The results of this study suggest that ESR and CRP are useful in excluding PJI, whereas both synovial white blood cell count and neutrophil percentage in hip aspirate are useful markers for diagnosing infection in MoP THA patients with head-neck taper corrosion associated adverse local tissue reaction.

Elevated ESR/CRP Ratio Is Associated With Reinfection After Debridement, Antibiotics, and Implant Retention in Chronic Periprosthetic Joint Infections.

BACKGROUND: Ratios of established inflammatory markers, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), have been used for diagnostic purposes in the surgical field; however, the ESR:CRP ratio (ECR) has not been evaluated as a marker for predicting infection resolution in patients with periprosthetic joint infections (PJIs). This study aimed to evaluate the diagnostic accuracy of ECR in predicting postoperative reinfection in patients who underwent debridement, antibiotics, and implant retention (DAIR). METHODS: This is a retrospective review of 179 consecutive patients who underwent DAIR revision total joint arthroplasty for PJI. Patients were stratified by acuity of their infection: acute PJI, acute hematogenous PJI, and chronic PJI. The area under the receiver operating characteristic curve was calculated to evaluate ECR as diagnostic marker for predicting postoperative reinfection in patients who underwent DAIR. RESULTS: Statistically significant differences in ECR were found in patients who underwent DAIR revision total joint arthroplasty for chronic infection (1.23 vs 2.33; P = .04). There was no significant difference in ECR in patients who underwent DAIR for acute infection (P = .70) and acute hematogenous infection (P = .56). In patients who underwent DAIR for chronic PJI, ECR demonstrated a sensitivity and specificity of 75% and 84%, respectively, for the prediction of postoperative reinfection, which was significantly higher than that of ESR (sensitivity, 67%; specificity, 47%; P < .001) and CRP (sensitivity, 50%; specificity, 26%; P < .001). CONCLUSION: Elevated ECR was associated with an increased reinfection risk in patients who underwent DAIR for chronic PJI, suggesting that preoperative ECR may be a useful predictor to identify patients at increased risk of reinfection after DAIR for chronic PJIs.

MARS MRI Characteristics of Adverse Local Tissue Reactions in Taper Corrosion of Metal-On-Polyethylene THA Differ From Metal-On-Metal THA.

BACKGROUND: Metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) has been recommended as a cross-sectional imaging modality in clinical evaluation of adverse local tissue reactions (ALTRs) in metal-on-metal (MoM) patients and metal-on-polyethylene (MoP) patients with taper corrosion. The aim of the study was to compare MARS MRI characteristics of ALTR in MoM total hip arthroplasty (THA) with ALTR in MoP THA with modular taper corrosion. METHODS: A total of 197 patients with ALTR were evaluated: 86 patients with MoM THA; 37 MoP patients with head-neck taper corrosion; and 74 MoP patients with neck-stem dual taper corrosion. MARS MRI scans were evaluated to identify location, size, type of ALTR (I-III), and associated ALTR synovitis (cystic, solid, and mixed). RESULTS: MARS MRI characteristics of ALTR were significantly different between the MoM and MoP groups (P = .017). The MoP group demonstrated the highest proportion of thick-walled cystic masses type II (56.7% in head-neck taper corrosion MoP and 46.5% in dual taper corrosion MoP vs 28.7% in MoM), whereas the MoM group had the highest proportion of thin-walled cystic masses type I. MoM implants (96.8%) were significantly more likely to have ALTR in multiple locations compared with both MoP groups (P = .001). CONCLUSION: This study demonstrates that MARS MRI characteristics of ALTR differ by bearing type with a significantly higher percentage of mixed type and solid type ALTR in the taper corrosion MoP THA compared with MoM THA. This information provides clinically useful information in evaluation of symptomatic MoP and MoM THA patients for ALTRs.

Outcome of Dual Mobility Constructs for Adverse Local Tissue Reaction Associated Abductor Deficiency in Revision Total Hip Arthroplasty.

BACKGROUND: Treatment of adverse local tissue reaction (ALTR) is challenging owing to high complications and poor outcomes after a revision surgery. As dislocation is the most common cause of reoperation, it is often necessary to use advanced articulations such as dual mobility. This study aims to evaluate the outcome and complication rates after revision surgery with dual mobility constructs, compared to constrained and conventional articulations in the setting of significant abductor deficiency due to ALTR. METHODS: Out of a total of 338 revision total hip arthroplasties for ALTR, 234 patients with a significant tissue necrosis and abductor muscle insufficiency (grade 3) were evaluated. The complication rates after revisions were compared between 42 hips with dual mobility implants, 24 hips with constrained liners, 104 hips with large diameter heads (36-40 mm), and 64 hips with small diameter heads (≤32 mm). RESULTS: After an average of 4 years of follow-up (2.8-8.6), the dual mobility articulation had no dislocation, compared to 4.1% and 15.5% for constrained liner and conventional articulations, respectively (P < .001). Utilization of dual mobility and constrained liner cup also did not increase the risk of nondislocation complications, including periprosthetic joint infection and periprosthetic fracture (P = .18 and .52). CONCLUSIONS: This study demonstrates significantly lower dislocation rates for dual mobility when compared to conventional articulations and comparable to constrained liners in cases of severe abductor deficiency due to ALTR, suggesting that dual mobility implants are viable surgical treatment alternatives to constrained liners to minimize dislocation during revision total hip arthroplasty in the setting of significant abductor deficiency due to ALTR.

Liver Bioengineering: Promise, Pitfalls, and Hurdles to Overcome.

PURPOSE OF REVIEW: In this review, we discuss the recent advancements in liver bioengineering and cell therapy and future advancements to improve the field towards clinical applications. RECENT FINDINGS: 3D printing, hydrogel-based tissue fabrication, and the use of native decellularized liver extracellular matrix as a scaffold are used to develop whole or partial liver substitutes. The current focus is on developing a functional liver graft through achieving a non-leaky endothelium and a fully constructed bile duct. Use of cell therapy as a treatment is less invasive and less costly compared to transplantation, however, lack of readily available cell sources with low or no immunogenicity and contradicting outcomes of clinical trials are yet to be overcome. SUMMARY: Liver bioengineering is advancing rapidly through the development of in vitro and in vivo tissue and organ models. Although there are major challenges to overcome, through optimization of the current methods and successful integration of induced pluripotent stem cells, the development of readily available, patient-specific liver substitutes can be achieved.