Reactive oxygen and nitrogen species induce protein and DNA modifications driving arthrofibrosis following total knee arthroplasty

Arthrofibrosis After Total Knee Arthroplasty: A Critical Analysis Review

» Arthrofibrosis after total knee arthroplasty (TKA) is the new formation of excessive scar tissue that results in limited ROM, pain, and functional deficits.» The diagnosis of arthrofibrosis is based on the patient's history, clinical examination, absence of alternative diagnoses from diagnostic testing, and operative findings. Imaging is helpful in ruling out specific causes of stiffness after TKA. A biopsy is not indicated, and no biomarkers of arthrofibrosis exist.» Arthrofibrosis pathophysiology is multifactorial and related to aberrant activation and proliferation of myofibroblasts that primarily deposit type I collagen in response to a proinflammatory environment. Transforming growth factor-beta signaling is the best established pathway involved in arthrofibrosis after TKA.» Management includes both nonoperative and operative modalities. Physical therapy is most used while revision arthroplasty is typically reserved as a last resort. Additional investigation into specific pathophysiologic mechanisms can better inform targeted therapeutics.

The epigenetic regulator BRD4 is required for myofibroblast differentiation of knee fibroblasts

Arthrofibrosis, which is characterized by excessive scar tissue and limited motion, can complicate the daily functioning of patients after total knee arthroplasty (TKA). Molecular hallmarks of arthrofibrosis include pathologic accumulation of myofibroblasts and disproportionate collagen deposition. Epigenetic mechanisms, including posttranslation modification of histones, control gene expression and may regulate fibrotic events. This study assessed the role of the bromodomain and extra-terminal (BET) proteins on myofibroblast differentiation. This group of epigenetic regulators recognize acetylated lysines and are targeted by a class of drugs known as BET inhibitors. RNA-seq analysis revealed robust mRNA expression of three BET members (BRD2, BRD3, and BRD4) while the fourth member (BRDT) is not expressed in primary TKA knee outgrowth fibroblasts. RT-qPCR and western blot analyses revealed that BET inhibition with the small molecule JQ1 impairs TGFβ1-induced expression of ACTA2, a key myofibroblast marker, in primary outgrowth knee fibroblasts. Similarly, JQ1 administration also reduced COL3A1 mRNA levels and collagen deposition as monitored by picrosirius red staining. Interestingly, the inhibitory effects of JQ1 on ACTA2 mRNA and protein expression, as well as COL3A1 expression and collagen deposition, were paralleled by siRNA-mediated depletion of BRD4. Together, these data reveal that BRD4-mediated epigenetic events support TGFβ1-mediated myofibroblast differentiation and collagen deposition as seen in arthrofibrosis. To our knowledge, these are the first studies that assess epigenetic regulators and their downstream events in the context of arthrofibrosis. Future studies may reveal clinical utility for drugs that target epigenetic pathways, specifically BET proteins, in the prevention and treatment of arthrofibrosis.

Hesperidin Methyl Chalcone Reduces the Arthritis Caused by TiO2 in Mice: Targeting Inflammation, Oxidative Stress, Cytokine Production, and Nociceptor Sensory Neuron Activation

Arthroplasty is an orthopedic surgical procedure that replaces a dysfunctional joint by an orthopedic prosthesis, thereby restoring joint function. Upon the use of the joint prosthesis, a wearing process begins, which releases components such as titanium dioxide (TiO₂) that trigger an immune response in the periprosthetic tissue, leading to arthritis, arthroplasty failure, and the need for revision. Flavonoids belong to a class of natural polyphenolic compounds that possess antioxidant and anti-inflammatory activities. Hesperidin methyl chalcone's (HMC) analgesic, anti-inflammatory, and antioxidant effects have been investigated in some models, but its activity against the arthritis caused by prosthesis-wearing molecules, such as TiO₂, has not been investigated. Mice were treated with HMC (100 mg/kg, intraperitoneally (i.p.)) 24 h after intra-articular injection of 3 mg/joint of TiO₂, which was used to induce chronic arthritis. HMC inhibited mechanical hyperalgesia, thermal hyperalgesia, joint edema, leukocyte recruitment, and oxidative stress in the knee joint (alterations in gp91^phox, GSH, superoxide anion, and lipid peroxidation) and in recruited leukocytes (total reactive oxygen species and GSH); reduced patellar proteoglycan degradation; and decreased pro-inflammatory cytokine production. HMC also reduced the activation of nociceptor-sensory TRPV1⁺ and TRPA1⁺ neurons. These effects occurred without renal, hepatic, or gastric damage. Thus, HMC reduces arthritis triggered by TiO₂, a component released upon wearing of prosthesis.

Biochemical markers of postsurgical knee arthrofibrosis: A systematic review

Introduction

Postsurgical knee arthrofibrosis is a common complication associated with pain and limited range of motion. Although the mechanism is unclear, many biochemical and genetic markers have been identified within arthrofibrotic knees. The purpose of this systematic review is to synthesize the many biochemical and genetic markers that have been associated with surgery-induced knee arthrofibrosis in order to better guide future therapeutic endeavors.

Methods

A thorough search of literature was conducted on April 27, 2022. Seventeen studies met inclusion criteria for this systematic review. Inclusion criteria for this study were as follows: title or abstract discussed biochemical and genetic markers associated with postoperative knee arthrofibrosis, study design included human and/or animal subjects.

Results

A wide variety of genetic biomarkers (mRNA), proteins/enzymes, and cytokines were identified in both animal models and human subjects with postsurgical knee arthrofibrosis. These included various extracellular matrix-encoding mRNA sequences, matrix metalloproteinases, proteins and mRNA sequences involved in Transforming Growth Factor-β signaling, and interleukin-family cytokines to name just a few.

Conclusion

There are many biomarkers found in postsurgical arthrofibrotic knees. TGF-β, and mRNA/proteins that participate in TGF-β signaling (i.e., LOX, SERPINE1, PAI-1/Akt/mTOR, BMP-2), appear to be particularly common. Future comparative studies should aim to determine which of these are most relevant, and therefore, worthwhile therapeutic targets.

Adaptive immune responses in patients requiring revision after total knee arthroplasty

Dissatisfaction occurs in nearly 20% of patients after total knee arthroplasty (TKA); however, there remains only limited understanding of the biologic mechanisms that may contribute to suboptimal postoperative outcomes requiring revision surgery. Expansion of effector T and B cells, could promote an abnormal healing response via local or peripheral immune system mechanisms and contribute to inferior outcomes necessitating revision TKA. In this pilot study, we hypothesized that patients suffering from complications of arthrofibrosis or instability may exhibit differences in adaptive immune function. Patients (n = 31) undergoing revision TKA for an indication of arthrofibrosis or instability were prospectively enrolled. Whole blood and synovial fluid (SF) from the operative knee were collected at time of surgery. Peripheral blood mononuclear cells were isolated and analyzed by flow cytometry. Serum and SF were assessed for immunoglobulin levels by Luminex and antiphospholipid antibodies by enzyme-linked immunoassay. No significant differences were observed in peripheral blood T/B cell populations or serum immunoglobulins levels between groups. SF analysis demonstrated significant differences between the two groups, with higher levels of immunoglobulin G1 (IgG1) (p = 0.0184), IgG3 (p = 0.0084) and antiphosphatidyl serine IgG (p = 0.034) in arthrofibrosis relative to instability patients. Increased levels of both IgG subclasses and antiphospholipid antibodies in the SF suggest that intra-articular T-B cell interactions, potentially triggered by exposure to apoptotic components generated during post-op healing, could be functioning as a source of immune complexes that fuel fibrous tissue growth in arthrofibrotic patients.

Human outgrowth knee fibroblasts from patients undergoing total knee arthroplasty exhibit a unique gene expression profile and undergo myofibroblastogenesis upon TGFβ1 stimulation

Arthrofibrosis is characterized by excessive extracellular matrix (ECM) deposition that results in restricted joint motion after total knee arthroplasties (TKAs). Currently, treatment options are limited. Therefore, an in vitro model of knee-related myofibroblastogenesis is valuable to facilitate investigation of the arthrofibrotic process, diagnostic and therapeutic options. In this study, we obtained intraoperative posterior capsule (PC), quadriceps tendon (QT), and suprapatellar pouch (SP) tissues from the knees of four patients undergoing primary TKAs for osteoarthritis. From these tissues, we isolated primary cells by the outgrowth method and subsequently characterized these cells in the absence and presence of the pro-myofibroblastic cytokine, transforming growth factor beta 1 (TGFβ1). Light microscopy of knee outgrowth cells revealed spindle-shaped cells, and immunofluorescence (IF) analysis demonstrated staining for the fibroblast-specific markers TE-7 and vimentin (VIM). These knee outgrowth fibroblasts differentiated readily into myofibroblasts as reflected by enhanced α-smooth muscle actin (ACTA2) mRNA and protein expression and increased mRNA expression of collagen type 1 (COL1A1) and type 3 (COL3A1) with collagenous matrix deposition in the presence of TGFβ1. Outgrowth knee fibroblasts were more sensitive to TGFβ1-mediated myofibroblastogenesis than adipose-derived mesenchymal stromal/stem cells (MSCs). While outgrowth knee fibroblasts isolated from three anatomical regions in four patients exhibited similar gene expression, these cells are distinct from other fibroblastic cell types (i.e., Dupuytren's fibroblasts) as revealed by RNA-sequencing. In conclusion, our study provides an in vitro myofibroblastic model of outgrowth knee fibroblasts derived from patients undergoing primary TKA that can be utilized to study myofibroblastogenesis and assess therapeutic strategies for arthrofibrosis.

Patients with Dupuytren's Contracture, Ledderhose Disease, and Peyronie's Disease are at higher risk of arthrofibrosis following total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is a successful treatment for patients with late stage osteoarthritis, yet arthrofibrosis remains a consistent cause of TKA failure. Dupuytren's, Ledderhose and Peyronie's Diseases are related conditions of increased fibroblast proliferation. The aim of this study was to identify whether an association exists between these conditions and arthrofibrosis following TKA.

METHODS

Patient records were queried from 2010 to 2016 using an administrative claims database to compare the rates of arthrofibrosis, manipulation under anesthesia (MUA), lysis of adhesions (LOA), and revision TKA in patients with independent chart diagnoses of Dupuytren's Contracture, Ledderhose, or Peyronie's Diseases versus those without. Complications were queried and compared using multivariate logistic regression.

RESULTS

Patients with Dupuytren's (n = 5,232) and Ledderhose (n = 50,716) had a significantly higher rate of ankylosis following TKA: 30-days (OR, 1.54; OR, 1.23), 90-days (OR, 1.20; OR, 1.24), 6-months (OR, 1.23; OR, 1.23), and 1-year (OR, 1.28; OR, 1.23), while patients with Peyronie's (n = 1,186) had a higher rate of diagnosis at 6-months (OR, 1.37) and 1-year (OR, 1.35). Patients with diagnoses of any of the fibroproliferative diseases had a statistically higher risk of MUA at 90-days, 6-month, and 1-year following primary TKA. These cohorts did not have a significantly higher rate of revision TKA.

CONCLUSION

There is an increased odds risk of arthrofibrosis and MUA in patients who have undergone TKA and have a diagnosis of Dupuytren's Contracture, Ledderhose, or Peyronie's Diseases. Improvements to frequency and application of post-operative treatment should be considered in these cohorts to improve outcomes.

Arthrofibrosis of the Ankle

Arthrofibrosis is a common, but often overlooked, condition that imparts significant morbidity following injuries and surgery to the foot and ankle. The most common etiologies are related to soft tissue trauma with subsequent fibrotic and contractile scar tissue formation within the ligaments and capsule of the ankle. This leads to pain, alterations in gait, and ankle dysfunction. Initial treatment often includes extensive physical therapy, however, if severe enough surgical options exist. Although the literature regarding ankle arthrofibrosis is scarce, this review article provides a greater understanding of the pathogenesis of arthrofibrosis and describes the current and future therapeutic options to treat fibrotic joints. Level of Evidence: Level V, expert opinion.

Molecular pathology of human knee arthrofibrosis defined by RNA sequencing

Arthrofibrosis is an abnormal histopathologic response, is debilitating for patients, and poses a substantial unsolved clinical challenge. This study characterizes molecular biomarkers and regulatory pathways associated with arthrofibrosis by comparing fibrotic and non-fibrotic human knee tissue. The fibrotic group encompasses 4 patients undergoing a revision total knee arthroplasty (TKA) for arthrofibrosis (RTKA-A) while the non-fibrotic group includes 4 patients undergoing primary TKA for osteoarthritis (PTKA) and 4 patients undergoing revision TKA for non-arthrofibrotic and non-infectious etiologies (RTKA-NA). RNA-sequencing of posterior capsule specimens revealed differences in gene expression between each patient group by hierarchical clustering, principal component analysis, and correlation analyses. Multiple differentially expressed genes (DEGs) were defined in RTKA-A versus PTKA patients (i.e., 2059 up-regulated and 1795 down-regulated genes) and RTKA-A versus RTKA-NA patients (i.e., 3255 up-regulated and 3683 down-regulated genes). Our findings define molecular and pathological markers of arthrofibrosis, as well as novel potential targets for risk profiling, early diagnosis and pharmacological treatment of patients.

Postoperative Serum Cytokine Levels Are Associated With Early Stiffness After Total Knee Arthroplasty: A Prospective Cohort Study

BACKGROUND

Inflammatory cytokines have been implicated in organ fibrosis; however, their role in the development of arthrofibrosis after total knee arthroplasty (TKA) has not been well explored. The purpose of this study is to assess whether perioperative synovial fluid or blood plasma cytokine levels are associated with reduced early post-TKA range of motion.

METHODS

A total of 179 patients with end-stage idiopathic osteoarthritis undergoing TKA were enrolled in this prospective cohort study. Synovial fluid and blood plasma were collected prearthrotomy and plasma was collected longitudinally in the postacute care unit and on postoperative days (PODs) 1 and 2. Stiffness was defined as ≤95° range of motion measured with a goniometer at 6 weeks (±2 weeks).

RESULTS

Thirty-two of 162 (19.8%) patients analyzed were stiff at 6 weeks postoperatively. Postoperative plasma levels of 9 cytokines (Eotaxin3, IL-5, IL12_23p40, IP10, VEGF, IL-7, IL-12p70, IL-16, IL-17a) were significantly different between stiff and nonstiff patients on POD1 and/or POD2. An association between preoperative plasma and synovial fluid cytokine levels and the development of postoperative stiffness was not detected.

CONCLUSION

The results of this study suggest that there is a distinct acute postoperative cytokine response profile in patients who develop stiffness 6 weeks after TKA. This profile was characterized by significant differences in levels of 9 cytokines over the first 2 postoperative days. These results identify cytokines that are potential biomarkers for risk of early stiffness after TKA and may play a role in the pathophysiology of this outcome.

Proteoglycan-4 regulates fibroblast to myofibroblast transition and expression of fibrotic genes in the synovium

Background

Synovial tissue fibrosis is common in advanced OA with features including the presence of stress fiber-positive myofibroblasts and deposition of cross-linked collagen type-I. Proteoglycan-4 (PRG4) is a mucinous glycoprotein secreted by synovial fibroblasts and is a major component of synovial fluid. PRG4 is a ligand of the CD44 receptor. Our objective was to examine the role of PRG4-CD44 interaction in regulating synovial tissue fibrosis in vitro and in vivo.

Methods

OA synoviocytes were treated with TGF-β ± PRG4 for 24 h and α-SMA content was determined using immunofluorescence. Rhodamine-labeled rhPRG4 was incubated with OA synoviocytes ± anti-CD44 or isotype control antibodies and cellular uptake of rhPRG4 was determined following a 30-min incubation and α-SMA expression following a 24-h incubation. HEK-TGF-β cells were treated with TGF-β ± rhPRG4 and Smad3 phosphorylation was determined using immunofluorescence and TGF-β/Smad pathway activation was determined colorimetrically. We probed for stress fibers and focal adhesions (FAs) in TGF-β-treated murine fibroblasts and fibroblast migration was quantified ± rhPRG4. Synovial expression of fibrotic markers: α-SMA, collagen type-I, and PLOD2 in Prg4 gene-trap (Prg4^GT) and recombined Prg4^GTR animals were studied at 2 and 9 months of age. Synovial expression of α-SMA and PLOD2 was determined in 2-month-old Prg4^GT/GT&Cd44^−/− and Prg4^GTR/GTR&Cd44^−/− animals.

Results

PRG4 reduced α-SMA content in OA synoviocytes (p < 0.001). rhPRG4 was internalized by OA synoviocytes via CD44 and CD44 neutralization attenuated rhPRG4’s antifibrotic effect (p < 0.05). rhPRG4 reduced pSmad3 signal in HEK-TGF-β cells (p < 0.001) and TGF-β/Smad pathway activation (p < 0.001). rhPRG4 reduced the number of stress fiber-positive myofibroblasts, FAs mean size, and cell migration in TGF-β-treated NIH3T3 fibroblasts (p < 0.05). rhPRG4 inhibited fibroblast migration in a macrophage and fibroblast co-culture model without altering active or total TGF-β levels. Synovial tissues of 9-month-old Prg4^GT/GT animals had higher α-SMA, collagen type-I, and PLOD2 (p < 0.001) content and Prg4 re-expression reduced these markers (p < 0.01). Prg4 re-expression also reduced α-SMA and PLOD2 staining in CD44-deficient mice.

Conclusion

PRG4 is an endogenous antifibrotic modulator in the joint and its effect on myofibroblast formation is partially mediated by CD44, but CD44 is not required to demonstrate an antifibrotic effect in vivo.

Anterior Cruciate Ligament Reconstruction Within 3 Weeks Does Not Increase Stiffness and Complications Compared With Delayed Reconstruction: A Meta-analysis of Randomized Controlled Trials

BACKGROUND

Injury-to-surgery time has been identified as a key point in anterior cruciate ligament (ACL) reconstruction, with early versus delayed treatment remaining a debated and controversial topic in the management of ACL tears.

PURPOSE/HYPOTHESIS

The aim was to quantitatively synthesize the best literature evidence by including only randomized controlled trials (RCTs) comparing early versus delayed ACL reconstruction, with a clear and univocal definition of cutoffs of early or delayed surgery. The hypothesis was that early treatment would lead to similar final clinical results compared with the delayed approach while providing a faster recovery without an increase in complications after ACL reconstruction.

STUDY DESIGN

Meta-analysis.

METHODS

A systematic literature search was performed on February 12, 2019, using PubMed, Web of Science, Cochrane Library, and gray literature databases. According to previous literature, 2 analyses with different cutoffs for injury-to-surgery time (3 weeks and 10 weeks) were performed to distinguish early and delayed reconstruction. The influence of timing was analyzed through meta-analyses in terms of patient-reported outcome measures (PROMs), risk of complications, range of motion (ROM) limitation, risk of retears, and residual laxity. Risk of bias and quality of evidence were assessed following the Cochrane guidelines.

RESULTS

Eight studies (5 in 3-week cutoff analysis and 3 in 10-week cutoff analysis) were included. No differences were found in terms of PROMs, risk of complications, ROM limitation, risk of retears, and residual laxity either in the 3-week cutoff analysis or in the 10-week cutoff analysis (P > .05). The level of evidence was moderate to low for the outcomes of the 3-week cutoff analysis and low to very low for the outcomes of the 10-week cutoff analysis.

CONCLUSION

This meta-analysis did not confirm the previously advocated benefits of delaying ACL surgery to avoid the acute posttraumatic phase. In fact, RCTs demonstrated that timing of surgery after ACL tears has no influence on the final functional outcome, risk of retears, or residual instability. While no data were available about the recovery time, literature results showed that early ACL reconstruction could be performed without increasing the risk of complications.

STUDY REGISTRATION

CRD42019119319 (PROSPERO).

Reactive oxygen/nitrogen species (ROS/RNS) and oxidative stress in arthroplasty

The interplay between implant design, biomaterial characteristics, and the local microenvironment adjacent to the implant is of utmost importance for implant performance and success of the joint replacement surgery. Reactive oxygen and nitrogen species (ROS/RNS) are among the various factors affecting the host as well as the implant components. Excessive formation of ROS and RNS can lead to oxidative stress, a condition that is known to damage cells and tissues and also to affect signaling pathways. It may further compromise implant longevity by accelerating implant degradation, primarily through activation of inflammatory cells. In addition, wear products of metallic, ceramic, polyethylene, or bone cement origin may also generate oxidative stress themselves. This review outlines the generation of free radicals and oxidative stress in arthroplasty and provides a conceptual framework on its implications for soft tissue remodeling and bone resorption (osteolysis) as well as implant longevity. Key findings derived from cell culture studies, animal models, and patients' samples are presented. Strategies to control oxidative stress by implant design and antioxidants are explored and areas of controversy and challenges are highlighted. Finally, directions for future research are identified. A better understanding of the host-implant interplay and the role of free radicals and oxidative stress will help to evaluate therapeutic approaches and will ultimately improve implant performance in arthroplasty.

The Comparison of Parameters of Oxidative Stress in Native Rat Livers Between Different Immunosuppressive Regimens

Background

It is thought that immunosuppressive treatment, besides anti-rejection properties, leads to pathological changes within the organ due to activation of mechanisms associated with oxidative stress. The aim of this study was to examine the parameters of oxidative stress in the livers of rats treated with the most commonly used transplant recipient drug regimens.

Material/Methods

The rat livers were obtained from archival material obtained from the previously performed experiment. Malondialdehyde (MDA), reduced glutathione (GSH) concentrations, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities were analyzed.

Results

Only the group treated with tacrolimus (T), mycophenolate mofetil (M), and prednisone (P), the TMP group, showed a slight increase in lipid peroxide concentration compared to the control group, though the difference was not statistically significant. Comparison of lipid peroxide concentration between the other treatment combinations and the control group showed a significant decrease. Additionally, a difference in lipid peroxide concentrations in the livers was observed between the cyclosporine A (C) group and tacrolimus (T) group. Alterations of other oxidative stress parameters were also observed in different regimens.

Conclusions

Long-lasting immunosuppressive treatment does indeed affect redox status; however, the antioxidant defenses of the liver against the effects of excess hydrogen peroxide are efficient, so the superoxide dismutase/glutathione peroxidase (SOD/GPx) and superoxide dismutase/catalase (SOD/CAT) ratios were not significant.

Vitamin C demand is increased after total knee arthroplasty: a double-blind placebo-controlled-randomized study

PURPOSE

This study was designed to determine whether perioperative supplementation of vitamin C (VC) improves range of motion (ROM) and reduces the risk of arthrofibrosis (AF) following total knee arthroplasty (TKA).

METHODS

Ninety-five patients undergoing TKA were randomized to either oral VC (1000 mg daily) or placebo for 50 days (48 VC group, 47 placebo group). The effect of VC supplementation was tested on ROM, AF, WOMAC, FJS-12, and VC plasma concentrations (VCc). VCc were analyzed in both patient groups before surgery, 4 and 7 days after surgery.

RESULTS

ROM at 1 year was not different between study groups. The prevalence of AF was 5 of 48 (10.4%) in the VC group compared to 11 of 47 (23.4%) in the placebo group (p = 0.09). VCc decreased post-operatively in the placebo group (49-12 µmol/l on day 7, p < 0.001), but not in the VC group (53-57 µmol/l). Patients with a perioperative drop of VCc ≥ 30 µmol/l developed significantly more AF at 1 year compared to patients with a VCc drop of < 30 µmol/l (p = 0.007).

CONCLUSIONS

TKA results in VC depletion. Perioperative VC supplementation prevents VCc drop in most patients undergoing TKA and may lower the incidence of AF. The clinical relevance of this study is that VC supplementation seems to be a cheap and safe adjunct to improve functional outcome after TKA.

LEVEL OF EVIDENCE

I.

TRIAL REGISTRY

The study was registered at the ISRCTN registry with study ID ISRCTN40250576.

Immunohistochemical examination in arthrofibrosis of the knee joint

INTRODUCTION

Arthrofibrosis (AF) is the result of increased cell proliferation and synthesis of matrix proteins (collagen I, III, and VI). Especially after invasive knee surgery, e.g., ligament reconstruction or knee replacement, abnormal fibroblast proliferation with pathological periarticular fibrosis can be observed leading to severely limited joint motion. The pathogenesis of AF is currently not fully understood. The present work aims to determine pathogenic factors.

MATERIALS AND METHODS

A descriptive, histological and immunohistochemical comparative study was performed on tissue samples of 14 consecutive patients undergoing arthrolysis for joint stiffness due to AF. Seven human autopsy specimens served as control. Samples were stained for expression of relevant markers such as CD68, α-smooth muscle actin (ASMA), beta-catenin, BMP-2 and examined for the histological grade of AF (cell-rich versus cell-poor) and compared to a control. Furthermore, a microscopic evaluation of the samples for cell differentiation and number was performed.

RESULTS

Tissue sections of cell-rich fibrosis showed a significantly higher expression of CD68 compared to the control with less than 10% of CD68 positive cells (p = 0.002). In cell-poor fibrosis no statistically significant difference was obvious (p = 0.228). Expression of ASMA in synovia, vessels, cell-rich and cell-poor fibrosis showed median values of 2.00 in the AF group and 1.75 in the control. Both groups differed significantly (p = 0.003). AF tissue showed a significantly difference in expression of β-catenin (p < 0.001) compared to the control. The overall difference between AF and control group in expression of BMP-2 was also statistically significant (p = 0.002).

CONCLUSIONS

Expression of CD68, ASMA, beta-catenin and BMP-2 is significantly increased in AF tissue samples. Based on presented findings, histological evaluation and immunohistochemical assessment of CD68, ASMA, β-catenin and BMP-2 expression may proof useful to diagnose AF and to analyze AF activity.

Low-grade infections as a possible cause of arthrofibrosis after total knee arthroplasty

Purpose

Arthrofibrosis after total knee arthroplasty represents a considerable burden for the patient and a therapeutic challenge for the practitioner. One possible cause discussed in the literature is a low-grade infection. This hypothesis should be examined within the scope of this retrospective study.

Patients and methods

Nineteen patients with clinical symptoms of arthrofibrosis after primary total knee arthroplasty were examined between January, 1999 and January, 2012. Incorrect positioning was radiologically ruled out. All patients were examined clinically (score of Freeman as well as Blauth and Jäger), radiologically (component and leg alignment, patella height according to Insall and Salvati), microbiologically (culture-based procedures), molecular biologically (PCR) and histologically in the course of an open revision of the prosthesis.

Results

According to the score of Freeman et al. (1977), a highly significant improvement in pain (p = 0.007) and in the overall score (p = 0.003) was shown. The knee joint mobility did not change significantly (p = 0.795). PCR was negative in 17 patients. One patient showed a PCR-positive result of the synovial membrane for Corynebacterium spp., while Staphylococcus warneri was detected in the culture. Another patient had a positive result of synovia PCR for Enterococcus cecorum as well as Corynebacterium spp. However, this culture was sterile. In 16 patient samples, no bacterial growth was detectable. Two samples were not evaluable. The main histopathological findings were synovialitis and fibrosis.

Conclusion

The hypothesis of low-grade-infection-induced arthrofibrosis after total knee arthroplasty could not be confirmed in this study. However, based on this small study population the conclusion needs to be confirmed by new and larger studies, ideally prospectively designed including a control group.

Increased Risk of Heterotopic Ossification Following Revision Hip Arthroplasty for Periprosthetic Joint Infection

BACKGROUND

To investigate whether surgery for Periprosthetic Joint Infection (PJI) of the hip, the number of procedures and their duration contribute to risk of Heterotopic Ossification formation.

METHODS

56 patients with hip PJI undergoing one-stage (10) or two-stage (46) exchange arthroplasty were matched to 112 patients undergoing revision arthroplasty for aseptic failure based on age, gender, body mass index (BMI), surgical approach (all direct lateral) and date of surgery (2006-2013). Patients with Paget's disease and ankylosing spondylitis, or preoperative HO were excluded. Perioperative pain management included use of the anti-inflammatory medications in all patients without prophylactic radiotherapy. Six-month postoperative radiographs were reviewed based on Brooker classification.

RESULTS

The incidence of overall HO in PJI and aseptic groups was 84% (47/56) and 11% (12/112), respectively. High grade HO (grades 3 and 4) in PJI and aseptic groups were 25% (24/56) and 4% (4/112), respectively. PJI was an independent risk factor for HO in the multivariate analysis (odds ratio of 9.3, 95% CI: 2.9-29.9, P<0.001).

CONCLUSION

Patients undergoing surgical treatment of hip PJI seem to be at increased risk of developing HO compared to aseptic failure. HO prophylaxis regimens may be recommendable in eligible patients undergoing surgical intervention for PJI of the hip.

LEVEL OF EVIDENCE

IV.

A Systems Biology Approach for Studying Heterotopic Ossification: Proteomic Analysis of Clinical Serum and Tissue Samples

Heterotopic ossification (HO) refers to the abnormal formation of bone in soft tissue. Although some of the underlying processes of HO have been described, there are currently no clinical tests using validated biomarkers for predicting HO formation. As such, the diagnosis is made radiographically after HO has formed. To identify potential and novel biomarkers for HO, we used isobaric tags for relative and absolute quantitation (iTRAQ) and high-throughput antibody arrays to produce a semi-quantitative proteomics survey of serum and tissue from subjects with (HO+) and without (HO-) heterotopic ossification. The resulting data were then analyzed using a systems biology approach. We found that serum samples from subjects experiencing traumatic injuries with resulting HO have a different proteomic expression profile compared to those from the matched controls. Subsequent quantitative ELISA identified five blood serum proteins that were differentially regulated between the HO+ and HO- groups. Compared to HO- samples, the amount of insulin-like growth factor I (IGF1) was up-regulated in HO+ samples, whereas a lower amount of osteopontin (OPN), myeloperoxidase (MPO), runt-related transcription factor 2 (RUNX2), and growth differentiation factor 2 or bone morphogenetic protein 9 (BMP-9) was found in HO+ samples (Welch two sample t-test; P < 0.05). These proteins, in combination with potential serum biomarkers previously reported, are key candidates for a serum diagnostic panel that may enable early detection of HO prior to radiographic and clinical manifestations.

Effect of long-term immunosuppressive therapy on native rat liver morphology and hepatocyte- apoptosis

A negative result of therapy based on immunosuppressive drugs is its leading to pathological alterations in the organ, including liver. Use of immunosuppressive medication may also lead to organized and genetically controlled cell death - apoptosis. The aim of this study was to examine histopathological changes in the livers of rats treated with immunosuppressive drugs, and also to determine the effects of different groups of immunosuppressive drugs on apoptosis activity in the hepatocytes of rat livers. The study was conducted on archival material obtained from Department of Nephrology, Transplantology and Internal Medicine of the Independent Public Clinical Hospital No. 2 at the Pomeranian Medical University in Szczecin, Poland. Statistical comparison of the treatment groups showed that all groups with rapamycin (sirolimus)-based regimens: Tacrolimus, Rapamycin, Glucocorticosteroid (TRG); Cyclosporine, Rapamycin, Glucocorticosteroid (CRG); Mycophenolate, Rapamycin, Glucocorticosteroid (MRG) and additionally Cyclosporine, Mycophenolate, Glucocorticosteroid (CMG) exhibited significantly more pronounced apoptosis than the control group, with p < 0.01, p < 0.05, p < 0.01 and p < 0.01, respectively. Furthermore, in the TRG group, over 90% of apoptotic hepatocytes were seen in the examined classic lobules. Additionally, every liver from treatment group was pathologically altered, including dilated sinusoids, pyknotic nuclei, swollen walls of the vessels. Long-lasting immunosuppressive treatment affects the liver both in terms of histological changes within the structure of the liver and in terms of the percentage of apoptotic hepatocytes. The following study seems to be very innovating due to the duration of the experiment and used drugs-protocols, since they reflect human treatment.

Myeloperoxidase as an Active Disease Biomarker: Recent Biochemical and Pathological Perspectives

Myeloperoxidase (MPO) belongs to the family of heme-containing peroxidases, produced mostly from polymorphonuclear neutrophils. The active enzyme (150 kDa) is the product of the MPO gene located on long arm of chromosome 17. The primary gene product undergoes several modifications, such as the removal of introns and signal peptides, and leads to the formation of enzymatically inactive glycosylated apoproMPO which complexes with chaperons, producing inactive proMPO by the insertion of a heme moiety. The active enzyme is a homodimer of heavy and light chain protomers. This enzyme is released into the extracellular fluid after oxidative stress and different inflammatory responses. Myeloperoxidase is the only type of peroxidase that uses H₂O₂ to oxidize several halides and pseudohalides to form different hypohalous acids. So, the antibacterial activities of MPO involve the production of reactive oxygen and reactive nitrogen species. Controlled MPO release at the site of infection is of prime importance for its efficient activities. Any uncontrolled degranulation exaggerates the inflammation and can also lead to tissue damage even in absence of inflammation. Several types of tissue injuries and the pathogenesis of several other major chronic diseases such as rheumatoid arthritis, cardiovascular diseases, liver diseases, diabetes, and cancer have been reported to be linked with MPO-derived oxidants. Thus, the enhanced level of MPO activity is one of the best diagnostic tools of inflammatory and oxidative stress biomarkers among these commonly-occurring diseases.

The role of monocytosis and neutrophilia in atherosclerosis

Monocytosis and neutrophilia are frequent events in atherosclerosis. These phenomena arise from the increased proliferation of hematopoietic stem and multipotential progenitor cells (HSPCs) and HSPC mobilization from the bone marrow to other immune organs and circulation. High cholesterol and inflammatory signals promote HSPC proliferation and preferential differentiation to the myeloid precursors (i.e., myelopoiesis) that than give rise to pro-inflammatory immune cells. These cells accumulate in the plaques thereby enhancing vascular inflammation and contributing to further lesion progression. Studies in animal models of atherosclerosis showed that manipulation with HSPC proliferation and differentiation through the activation of LXR-dependent mechanisms and restoration of cholesterol efflux may have a significant therapeutic potential.

Total Knee Arthroplasty in Patients with Retention of Prior Hardware Material: What is the Outcome?

BACKGROUND

There is an information gap in literature regarding postoperative outcome of total knee arthroplasty (TKA) in patients with hardware in-situ from the previous knee surgery. The present study aims to evaluate impact of retained hardware on short-term outcome of TKA patients.

METHODS

Perioperative radiographs of patients who had undergone TKA between 2007 and 2012 were reviewed and patients in whom partial or complete retention of hardware was evident after TKA were included. These patients were matched in 1 to 2 ratio based on age (+/- 2 years), gender, surgeon and year of surgery to a group of patients that underwent primary TKA without hardware in the affected knee. The average follow up of these patients was 43.45 (range 12-155.2) months. Complication rates were compared between the two groups using statistical tests that took into account the matched data structure.

RESULTS

We included a total of 55 cases and 110 controls. The incidence of complications was higher, although not all statistically significant, in the case group. Only mechanical complications were significantly different in the cases group (5.5% versus 0%, P=0.01). Time to event analysis using the mixed-effects Cox model didn't show a statistically significant difference between two groups for various outcomes.

CONCLUSION

Presence of retained hardware around the knee may predispose the patient to a higher rate of complications particularly mechanical complications of the implant after TKA. Further studies are required to investigate impact of retained hardware around the knee in patients undergoing TKA.Level of evidence: III.

Developmental neurotoxic effects of a low dose of TCE on a 3-D neurosphere system

Trichloroethylene (TCE) is one of the industrial toxic byproducts that now persist in the air, soil, and water. Several studies have already illustrated the toxic effect of high doses of TCE on the biological functions of several organs. This study aims to highlight the toxic impact of a low dose of TCE (1 μmol/L) on the development of rat neural stem cells (NSCs). The subventricular zones (SVZ) of rat pup's brains were collected and minced, and the harvested cells were cultured in the presence of neural growth factors B27/N2 to develop neurospheres. The cells were then exposed to a dose of 1 μmol/L TCE for 1 or 2 weeks. The outcomes indicated a remarkable inhibitory effect of TCE on the differentiation capacity of NSCs, which was confirmed by down-regulation of the astrocyte marker GFAP The inhibitory effect of TCE on the proliferation of NSCs was identified by the reductions in neurosphere diameter, Ki67 expression, and cell cycle arrest at the G1/S phase. Immunolabelling with annexin V indicated the proapoptotic effect of TCE exposure. PCR results revealed a TCE-mediated suppression of the expression of the antioxidant enzyme SOD1. This paper illustrates, for the first time, a detailed examination of the toxic effects of an environmentally low dose of TCE on NCSs at the transcriptional, translational, and functional levels.

Arthrofibrosis Associated With Total Knee Arthroplasty

BACKGROUND

Arthrofibrosis is a debilitating postoperative complication of total knee arthroplasty (TKA). It is one of the leading causes of hospital readmission and a predominant reason for TKA failure. The prevalence of arthrofibrosis will increase as the annual incidence of TKA in the United States rises into the millions.

METHODS

In a narrative review of the literature, the etiology, economic burden, treatment strategies, and future research directions of arthrofibrosis after TKA are examined.

RESULTS

Characterized by excessive proliferation of scar tissue during an impaired wound healing response, arthrofibrotic stiffness causes functional deficits in activities of daily living. Postoperative, supervised physiotherapy remains the first line of defense against the development of arthrofibrosis. Also, adjuncts to traditional physiotherapy such as splinting and augmented soft tissue mobilization can be beneficial. The effectiveness of rehabilitation on functional outcomes depends on the appropriate timing, intensity, and progression of the program, accounting for the patient's ability and level of pain. Invasive treatments such as manipulation under anesthesia, debridement, and revision arthroplasty improve range of motion, but can be traumatic and costly. Future studies investigating novel treatments, early diagnosis, and potential preoperative screening for risk of arthrofibrosis will help target those patients who will need additional attention and tailored rehabilitation to improve TKA outcomes.

CONCLUSION

Arthrofibrosis is a multi-faceted complication of TKA, and is difficult to treat without an early, tailored, comprehensive rehabilitation program. Understanding the risk factors for its development and the benefits and shortcomings of various interventions are essential to best restore mobility and function.

Combination of tacrolimus and mycophenolate mofetil induces oxidative stress and genotoxicity in spleen and bone marrow of Wistar rats

Tacrolimus (TAC) and mycophenolate mofetil (MMF) are common immunosuppressive drugs used to avoid immunological rejection of transplanted organs. The risk of developing cancer is the most critical complication in organ transplant recipients undergoing immunosuppressive therapy. This study aims to explore the cytotoxic and genotoxic effects of TAC and MMF alone or combined orally administrated on spleen and bone marrow of Wistar rats. Our results showed that TAC (2.4; 24 and 60mg/kg) and MMF (5; 50 and 125mg/kg) induced a genotoxic effect on rat bone marrow. Moreover, the co-treatment with the TAC/MMF (2.4/5mg/kg b.w.; 2.4/50mg/kg b.w. and 60/50mg/kg b.w.) produce a genotoxicity as measured by micronuclei (MN) frequencies, chromosomal aberrations (CA) rates and DNA damage levels. Furthermore, the TAC and MMF-treated animals developed oxidative stress in spleen, indicated by a significant increase of malondialdehyde (MDA), protein oxidation and decrease of anti-oxidant enzymes levels such as catalase (CAT) and superoxide dismutase (SOD). This damage was associated with an increase of DNA fragmentation. Co-treatment with TAC/MMF synergistically induced markers of oxidative stress in rat splenic tissue. In conclusion, TAC/MMF associated induction in oxidative stress plays a role in the splenic and bone marrow toxicity and enhances the different endpoints of genotoxicity, suggesting its mutagenic action in vivo.

Adverse Biological Effect of TiO₂ and Hydroxyapatite Nanoparticles Used in Bone Repair and Replacement

The adverse biological effect of nanoparticles is an unavoidable scientific problem because of their small size and high surface activity. In this review, we focus on nano-hydroxyapatite and TiO₂ nanoparticles (NPs) to clarify the potential systemic toxicological effect and cytotoxic response of wear nanoparticles because they are attractive materials for bone implants and are widely investigated to promote the repair and reconstruction of bone. The wear nanoparticles would be prone to binding with proteins to form protein-particle complexes, to interacting with visible components in the blood including erythrocytes, leukocytes, and platelets, and to being phagocytosed by macrophages or fibroblasts to deposit in the local tissue, leading to the formation of fibrous local pseudocapsules. These particles would also be translocated to and disseminated into the main organs such as the lung, liver and spleen via blood circulation. The inflammatory response, oxidative stress, and signaling pathway are elaborated to analyze the potential toxicological mechanism. Inhibition of the oxidative stress response and signaling transduction may be a new therapeutic strategy for wear debris-mediated osteolysis. Developing biomimetic materials with better biocompatibility is our goal for orthopedic implants.

Predominance of synovial sensory nerve fibers in arthrofibrosis following total knee arthroplasty compared to osteoarthritis of the knee

BACKGROUND

So far, there exists no golden standard for the treatment of arthrofibrosis (AF) following total knee arthroplasty (TKA). Although pain is a hallmark of AF, nociceptive nerve fibers have never been investigated in affected joint tissue.

METHODS

A total of 24 patients with osteoarthritis (OA) of the knee (n = 12) and post-TKA AF of the knee (n = 12) were included. Along evaluation of typical clinical signs and symptoms by using the Knee Society Clinical Rating System (KSS), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC index), the innervation of joint tissue was studied by semiquantitative immunofluorescence of nerve fibers.

RESULTS

Patients with AF compared to OA had a lower KSS and lower KOOS. In all compartments (anterior, medial, and lateral recesses), the density of synovial sympathetic nerve fibers was significantly higher in OA compared to AF, which was also true for the density of sensory nerve fibers in the medial and lateral recesses. In synovial tissue of the anterior recess of patients with AF compared to OA, the density of nociceptive sensory nerve fibers was significantly higher relative to sympathetic nerve fibers. This was similarly observed in the neighboring infrapatellar fat pad of the knee.

CONCLUSIONS

Similar as in many painful musculoskeletal diseases, this study indicates that patients with arthrofibrosis of the knee after TKA demonstrate a preponderance of profibrotic sensory nerve fibers over antifibrotic sympathetic nerve fibers. This could serve as a starting point for AF therapy with specific antifibrotic pain medication or regional anesthetic techniques.

Homogenization of tissues via picosecond-infrared laser (PIRL) ablation: Giving a closer view on the in-vivo composition of protein species as compared to mechanical homogenization

Posttranslational modifications and proteolytic processing regulate almost all physiological processes. Dysregulation can potentially result in pathologic protein species causing diseases. Thus, tissue species proteomes of diseased individuals provide diagnostic information. Since the composition of tissue proteomes can rapidly change during tissue homogenization by the action of enzymes released from their compartments, disease specific protein species patterns can vanish. Recently, we described a novel, ultrafast and soft method for cold vaporization of tissue via desorption by impulsive vibrational excitation (DIVE) using a picosecond-infrared-laser (PIRL). Given that DIVE extraction may provide improved access to the original composition of protein species in tissues, we compared the proteome composition of tissue protein homogenates after DIVE homogenization with conventional homogenizations. A higher number of intact protein species was observed in DIVE homogenates. Due to the ultrafast transfer of proteins from tissues via gas phase into frozen condensates of the aerosols, intact protein species were exposed to a lesser extent to enzymatic degradation reactions compared with conventional protein extraction. In addition, total yield of the number of proteins is higher in DIVE homogenates, because they are very homogenous and contain almost no insoluble particles, allowing direct analysis with subsequent analytical methods without the necessity of centrifugation.

Biological significance

Enzymatic protein modifications during tissue homogenization are responsible for changes of the in-vivo protein species composition. Cold vaporization of tissues by PIRL-DIVE is comparable with taking a snapshot at the time of the laser irradiation of the dynamic changes that occur continuously under in-vivo conditions. At that time point all biomolecules are transferred into an aerosol, which is immediately frozen.

Knee manipulation under anaesthetic following total knee arthroplasty

The purpose of this study was to compare clinical outcomes of total knee arthroplasty (TKA) after manipulation under anaesthesia (MUA) for post-operative stiffness with a matched cohort of TKA patients who did not requre MUA.

In total 72 patients (mean age 59.8 years, 42 to 83) who underwent MUA following TKA were identified from our prospective database and compared with a matched cohort of patients who had undergone TKA without subsequent MUA. Patients were evaluated for range of movement (ROM) and clinical outcome scores (Western Ontario and McMaster Universities Arthritis Index, Short-Form Health Survey, and Knee Society Clinical Rating System) at a mean follow-up of 36.4 months (12 to 120). MUA took place at a mean of nine weeks (5 to 18) after TKA. In patients who required MUA, mean flexion deformity improved from 10° (0° to 25°) to 4.4° (0° to 15°) (p < 0.001), and mean range of flexion improved from 79.8° (65° to 95°) to 116° (80° to 130°) (p < 0.001). There were no statistically significant differences in ROM or functional outcome scores at three months, one year, or two years between those who required MUA and those who did not. There were no complications associated with manipulation.

At most recent follow-up, patients requiring MUA achieved equivalent ROM and clinical outcome scores when compared with a matched control group. While other studies have focused on ROM after manipulation, the current study adds to current literature by supplementing this with functional outcome scores.

Cite this article: Bone Joint J 2015;97-B:1640–4.

MicroRNA-mediated immune modulation as a therapeutic strategy in host-implant integration

The concept of implanting an artificial device into the human body was once the preserve of science fiction, yet this approach is now often used to replace lost or damaged biological structures in human patients. However, assimilation of medical devices into host tissues is a complex process, and successful implant integration into patients is far from certain. The body's immediate response to a foreign object is immune-mediated reaction, hence there has been extensive research into biomaterials that can reduce or even ablate anti-implant immune responses. There have also been attempts to embed or coat anti-inflammatory drugs and pro-regulatory molecules onto medical devices with the aim of preventing implant rejection by the host. In this review, we summarize the key immune mediators of medical implant reaction, and we evaluate the potential of microRNAs to regulate these processes to promote wound healing, and prolong host-implant integration.

Effect of recombinant human erythropoietin on mitomycin C-induced oxidative stress and genotoxicity in rat kidney and heart tissues

Mitomycin C (MMC) is an antineoplastic agent used for the treatment of several human malignancies. Nevertheless, the prolonged use of the drug may result in a serious heart and kidney injuries. Recombinant human erythropoietin (rhEPO) has recently been shown to exert an important cytoprotective effect in experimental brain injury and ischemic acute renal failure. The aim of the present work is to investigate the cardioprotective and renoprotective effects of rhEPO against MMC-induced oxidative damage and genotoxicity. Our results showed that MMC induced oxidative stress and DNA damage. rhEPO administration in any treatment conditions decreased oxidative damage induced by MMC. It reduced malondialdehyde and protein carbonyl levels. rhEPO ameliorated reduced glutathione plus oxidized glutathione modulation and the increased catalase activity after MMC treatment. Furthermore, rhEPO restored DNA damage caused by MMC. We concluded that rhEPO administration especially in pretreatment condition protected rats against MMC-induced heart and renal oxidative stress and genotoxicity.

DNA damage at respiratory distress, but not acute time-points, correlates with tissue fibrosis following thoracic radiation exposure in mice

PURPOSE

Radiation exposure can result in DNA damage but whether the extent of DNA damage correlates with the radiation-induced tissue injury in the lung is not known. We aimed to determine whether numbers of γH2AX foci, representing histone H2AX phosphorylation a marker of DNA damage, measured within days of radiation exposure, correlated with known later lung injury responses in eight inbred mouse strains.

MATERIALS AND METHODS

Mice received 18 Gy pulmonary irradiation and numbers of γH2AX positive nuclei in the lung were immunohistochemically determined.

RESULTS

Numbers of γH2AX foci, assessed up to seven days post irradiation did not correlate with pulmonary fibrosis. γH2AX counts from mice in respiratory distress, however, significantly correlated with fibrosis and lungs from mice treated with a fibrosis-reducing antagonist had fewer γH2AX foci.

CONCLUSIONS

Acute response measures of pulmonary DNA damage did not predict for pathology, but levels of this marker in distressed mice were correlative of fibrosis.

Do various factors affect the frequency of manipulation under anesthesia after primary total knee arthroplasty?

BACKGROUND

One of the most important goals of primary total knee arthroplasty (TKA) is to achieve a functional range of motion (ROM). However, up to 20% of patients fail to do so, which can impair activities of daily living.

QUESTIONS/PURPOSES

The purpose of this study was to evaluate the effect of various (1) demographic factors; (2) comorbidities; and (3) knee-specific factors on the frequency of manipulation under anesthesia, which was used as an indicator of knee stiffness after a primary TKA.

METHODS

We evaluated the registries of two high-volume centers and reviewed all 3182 TKAs that were performed between 2005 and 2011 to identify all patients who had undergone manipulation under anesthesia (MUA). A total of 156 knees in 133 patients underwent MUA after an index arthroplasty. These patients were compared in a one-to-four ratio with a group of patients with satisfactory ROM drawn from the same database who met prespecified criteria and who had not undergone MUA. Effects of various factors, including age, sex, body mass index, race, comorbidities, and the underlying cause of knee arthritis, were compared between these two cohorts using multivariable logistic regressions.

RESULTS

After controlling for various confounding, nonwhite race was associated with an increase (odds ratio [OR], 2.01; p=0.03), and age≥65 years (OR, 0.17; 95% confidence interval [CI], 0.04-0.74; p=0.0179) was associated with a reduction in the incidence of MUA. In comorbidities, diabetes (OR, 1.72; 95% CI, 1.02-2.32; p=0.03), high cholesterol levels (OR, 2.70; p=0.03), and tobacco smoking (OR, 1.59; 95% CI, 1.03-2.47; p=0.03) were associated with an increase in frequency of MUA. In knee-specific factors, preoperative knee ROM of less than 100° (OR, 0.80; p<0.0001) and knee osteonecrosis (p=3.61; 95% CI, 1.29-10.1; p=0.014) were associated with increased frequency of MUA.

CONCLUSIONS

We identified several demographic, medical, and knee-specific factors that were associated with poor postoperative ROM in our patients undergoing TKA. Patients who have multiple risk factors may benefit from preoperative counseling to set realistic ROM expectations.

LEVEL OF EVIDENCE

Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

A novel model of chronic wounds: importance of redox imbalance and biofilm-forming bacteria for establishment of chronicity

Chronic wounds have a large impact on health, affecting ∼6.5 M people and costing ∼$25B/year in the US alone. We previously discovered that a genetically modified mouse model displays impaired healing similar to problematic wounds in humans and that sometimes the wounds become chronic. Here we show how and why these impaired wounds become chronic, describe a way whereby we can drive impaired wounds to chronicity at will and propose that the same processes are involved in chronic wound development in humans. We hypothesize that exacerbated levels of oxidative stress are critical for initiation of chronicity. We show that, very early after injury, wounds with impaired healing contain elevated levels of reactive oxygen and nitrogen species and, much like in humans, these levels increase with age. Moreover, the activity of anti-oxidant enzymes is not elevated, leading to buildup of oxidative stress in the wound environment. To induce chronicity, we exacerbated the redox imbalance by further inhibiting the antioxidant enzymes and by infecting the wounds with biofilm-forming bacteria isolated from the chronic wounds that developed naturally in these mice. These wounds do not re-epithelialize, the granulation tissue lacks vascularization and interstitial collagen fibers, they contain an antibiotic-resistant mixed bioflora with biofilm-forming capacity, and they stay open for several weeks. These findings are highly significant because they show for the first time that chronic wounds can be generated in an animal model effectively and consistently. The availability of such a model will significantly propel the field forward because it can be used to develop strategies to regain redox balance that may result in inhibition of biofilm formation and result in restoration of healthy wound tissue. Furthermore, the model can lead to the understanding of other fundamental mechanisms of chronic wound development that can potentially lead to novel therapies.

Why are total knee arthroplasties failing today--has anything changed after 10 years?

The purpose of this study was to determine the frequency and cause of failure after total knee arthroplasty and compare the results with those reported by our similar investigation conducted 10 years ago. A total of 781 revision TKAs performed at our institution over the past 10 years were identified. The most common failure mechanisms were: loosening (39.9%), infection (27.4%), instability (7.5%), periprosthetic fracture (4.7%), and arthrofibrosis (4.5%). Infection was the most common failure mechanism for early revision (<2 years from primary) and aseptic loosening was the most common reason for late revision. Polyethylene (PE) wear was no longer the major cause of failure. Compared to our previous report, the percentage of revisions performed for polyethylene wear, instability, arthrofibrosis, malalignment and extensor mechanism deficiency has decreased.

Potential Chemoprevention of 7,12-Dimethylbenz[a]anthracene Induced Renal Carcinogenesis by Moringa oleifera Pods and Its Isolated Saponin

Present investigation shows that hydroethanolic extract of Moringa oleifera (MOHE) and its isolated saponin (SM) attenuates DMBA induced renal carcinogenesis in mice. Isolation of SM was achieved by TLC and HPLC and characterization was done using IR and (1)H NMR. Animals were pre-treated with MOHE (200 and 400 mg/kg body weight; p.o), BHA as a standard (0.5 and 1 %) and SM (50 mg/kg body weight) for 21 days prior to the administration of single dose of DMBA (15 mg/kg body weight). Administration of DMBA significantly (p < 0.001) enhanced level of xenobiotic enzymes. It enhanced renal malondialdehyde, with reduction in renal glutathione content, antioxidant enzymes and glutathione-S-transferase. The status of renal aspartate transaminase, alanine transaminase, alkaline phosphatase and total protein content were also found to be decreased along with increase in total cholesterol in DMBA administered mice. Pretreatment with MOHE and SM significantly reversed the DMBA induced alterations in the tissue and effectively suppressed renal oxidative stress and toxicity.

The role of oxidative stress in aseptic loosening of total hip arthroplasties

This study investigated the hypothesis that wear particle-induced oxidative stress initiates osteolysis after total hip arthroplasty (THA). Patient radiographs were scored for osteolysis and periprosthetic tissues were immunostained and imaged to quantify polyethylene wear, inflammation, and five osteoinflammatory and oxidative stress-responsive factors. These included high mobility group protein-B1 (HMGB1), cyclooxygenase-2 (COX2), inducible nitric oxide synthase (iNOS), 4-hydroxynonenal (4-HNE), and nitrotyrosine (NT). The results show wear debris correlated with inflammation, 4-HNE, NT and HMGB1, whereas inflammation only correlated with NT and HMGB1. Similar to wear debris and inflammation, osteolysis correlated with HMGB1. Additionally, osteolysis correlated with COX2 and 4-HNE, but not iNOS or NT. Understanding the involvement of oxidative stress in wear-induced osteolysis will help identify diagnostic biomarkers and therapeutic targets to prevent osteolysis after THA.

Infrared microspectroscopy identifies biomolecular changes associated with chronic oxidative stress in mammary epithelium and stroma of breast tissues from healthy young women: implications for latent stages of breast carcinogenesis

Studies of the decades-long latent stages of breast carcinogenesis have been limited to when hyperplastic lesions are already present. Investigations of earlier stages of breast cancer (BC) latency have been stymied by the lack of fiducial biomarkers needed to identify where in histologically normal tissues progression toward a BC might be taking place. Recent evidence suggests that a marker of chronic oxidative stress (OxS), protein adducts of 4-hydroxy-2-nonenal (4HNE), can meet this need. Specifically: (1) 4HNE immunopositive (4HNE+) mammary epithelial (ME) cells were found to be prevalent in normal (reduction mammoplasty) tissues of most women (including many teenagers) studied, representative of those living in the United States' high risk-posing environment and: (2) marked (> 1.5-fold) differences were identified between tissues of healthy young women with many vs. few 4HNE+ ME cells in the relative levels of transcripts for 42 of the 84 OxS-associated genes represented in SABioscience Oxidative-Stress/Oxidative-Defense PCR array. Herein we used synchrotron radiation-based Fourier-transform infrared (SR-FTIR) microspectroscopy to identify molecular changes associated with 4HNE adducts in basal and luminal ME cells in terminal ductal units (TDLU), which are the cells of origin of BC, and associated intralobular and interlobular stroma, known contributors to carcinogenesis. Multivariate analysis-derived wavenumbers differentiated 4HNE+ and 4HNE- cells in each of the anatomical compartments. Specifically, principal component and linear discriminant analyses of mid-infrared spectra obtained from these cells revealed unambiguous, statistically highly significant differences in the "biochemical fingerprint" of 4HNE+ vs. 4HNE- luminal and basal ME cells, as well as between associated intralobular and interlobular stroma. These findings demonstrate further SR-FTIR microspectroscopy's ability to identify molecular changes associated with altered physiological and/or pathophysiological states, in this case with a state of chronic OxS that provides a pro-carcinogenic microenvironment.

Antioxidant and antigenotoxic role of recombinant human erythropoeitin against alkylating agents: Cisplatin and mitomycin C in cultured Vero cells

Cisplatin (CDDP) and mitomycin C (MMC), two alkylating agents used against various solid tumours, are a common source of acute kidney injury. Thus, strategies for minimizing CDDP and MMC toxicity are of a clinical interest. In this study, we aimed to investigate the protective role of recombinant human erythropoietin (rhEPO) against oxidative stress and genotoxicity induced by CDDP and MMC in cultured Vero cells. Three types of treatments were performed: (i) cells were treated with rhEPO 24 h before exposure to CDDP/MMC (pre-treatment), (ii) cells were treated with rhEPO and CDDP/MMC simultaneously (co-treatment), (iii) cells were treated with rhEPO 24 h after exposure to CDDP/MMC (post-treatment). Our results showed that rhEPO decreased the reactive oxygen species levels, the malondialdehyde levels and ameliorated glutathione (reduced and oxidized glutathione) modulation induced by CDDP and MMC in cultured Vero cells. Furthermore, rhEPO administration prevented alkylating agents-induced DNA damage accessed by comet test. Altogether, our results suggested a protective role of rhEPO, against CDDP- and MMC-induced oxidative stress and genotoxicity, especially in pre-treatment condition.

An Escherichia coli effector protein promotes host mutation via depletion of DNA mismatch repair proteins

Enteropathogenic Escherichia coli (EPEC) is an attaching and effacing (A/E) human pathogen that causes diarrhea during acute infection, and it can also sustain asymptomatic colonization. A/E E. coli depletes host cell DNA mismatch repair (MMR) proteins in colonic cell lines and has been detected in colorectal cancer (CRC) patients. However, until now, a direct link between infection and host mutagenesis has not been fully demonstrated. Here we show that the EPEC-secreted effector protein EspF is critical for complete EPEC-induced depletion of MMR proteins. The mechanism of EspF activity on MMR protein was posttranscriptional and dependent on EspF mitochondrial targeting. EPEC infection also induced EspF-independent elevation of host reactive oxygen species levels. Moreover, EPEC infection significantly increased spontaneous mutation frequency in host cells, and this effect was dependent on mitochondrially targeted EspF. Taken together, these results support the hypothesis that A/E E. coli can promote colorectal carcinogenesis in humans.

There is mounting evidence linking the gut microbiota with the induction of colorectal tumorigenesis. We previously described the downregulation of host cell mismatch repair (MMR) protein levels upon enteropathogenic Escherichia coli (EPEC) infection and speculated that this depletion may lead to an ablated DNA repair system. In this work, we identify EspF, a translocated EPEC effector protein, as one of the factors required for this phenotype and show that this effector protein must be targeted to the mitochondria in order to exert its effect. Furthermore, we found that the impaired mismatch repair system resulting from EPEC infection led to the generation of spontaneous mutations within host DNA at a site of microsatellite instability, a trait typical of colorectal tumors. Thus, this work provides a novel means by which enteric bacteria may promote colorectal carcinogenesis.

An Escherichia coli effector protein promotes host mutation via depletion of DNA mismatch repair proteins

Enteropathogenic Escherichia coli (EPEC) is an attaching and effacing (A/E) human pathogen that causes diarrhea during acute infection, and it can also sustain asymptomatic colonization. A/E E. coli depletes host cell DNA mismatch repair (MMR) proteins in colonic cell lines and has been detected in colorectal cancer (CRC) patients. However, until now, a direct link between infection and host mutagenesis has not been fully demonstrated. Here we show that the EPEC-secreted effector protein EspF is critical for complete EPEC-induced depletion of MMR proteins. The mechanism of EspF activity on MMR protein was posttranscriptional and dependent on EspF mitochondrial targeting. EPEC infection also induced EspF-independent elevation of host reactive oxygen species levels. Moreover, EPEC infection significantly increased spontaneous mutation frequency in host cells, and this effect was dependent on mitochondrially targeted EspF. Taken together, these results support the hypothesis that A/E E. coli can promote colorectal carcinogenesis in humans.

Increased BMP expression in arthrofibrosis after TKA

PURPOSE

Because of the multiple possible aetiologies of painful total knee arthroplasty (TKA), the diagnosis and treatment of such patients are challenging. In a considerable number of patients, an intraarticular pathology is present, although not verifiable with clinical and diagnostic imaging techniques as in cases of primary arthrofibrosis. In these patients, the differentiation between intra- and extraarticular causes of pain remains difficult. Until now, little attention has been paid to changes of the synovial fluid and tissue in these knees. The objective of this study was to analyse the changes of the synovial environment in patients suffering from arthrofibrosis after TKA in comparison with knees with referred pain suffering from hip arthritis. The changes of the synovial environment probably provide additional diagnostic information to verify an intraarticular pathology.

METHODS

The synovial fluid of 10 consecutive knees in 10 patients presenting with a primary arthrofibrosis after TKA without signs of infection, instability, malalignment, or loosening was analysed and compared to the synovial fluid of 10 knees with referred pain serving as controls. The BMP-2 concentration was measured in the synovial fluid, and the presence of cytokines leading to an overexpression of BMP-2 was detected by measuring the change of BMP-2 expression in a synoviocyte cell line following exposing to the synovial fluid of the patients.

RESULTS

The concentration of BMP-2 in the synovial fluid was significantly higher in arthrofibrotic TKA knees (24.3 ± 6.9 pg/mL), compared with the control group 5.9 ± 4.8 pg/mL (P < 0.001). Corresponding to this finding, BMP-2 expression in synoviocytes was upregulated 11.5-fold (P < 0.05) by synovial fluid of patients suffering from arthrofibrosis after TKA, compared with the control group with referred pain.

CONCLUSION

BMP-2 is overexpressed and its concentrations are consequently higher in patients suffering from arthrofibrosis after TKA. The synovial BMP-2 concentration may be a potential marker for differentiating between intra- and extraarticular causes of pain.

LEVEL OF EVIDENCE

II.

BMP-2 Dependent Increase of Soft Tissue Density in Arthrofibrotic TKA

Arthrofibrosis after total knee arthroplasty (TKA) is difficult to treat, as its aetiology remains unclear. In a previous study, we established a connection between the BMP-2 concentration in the synovial fluid and arthrofibrosis after TKA. The hypothesis of the present study was, therefore, that the limited range of motion in arthrofibrosis is caused by BMP-2 induced heterotopic ossifications, the quantity of which is dependent on the BMP-2 concentration in the synovial fluid.

Eight patients with arthrofibrosis after TKA were included. The concentration of BMP-2 in the synovial fluid from each patient was determined by ELISA. Radiologically, digital radiographs were evaluated and the grey scale values were determined as a measure of the tissue density of defined areas. Apart from air, cutis, subcutis and muscle, the soft-tissue density in the area of the capsule of the suprapatellar pouch was determined. The connection between the BMP-2 concentration and the soft-tissue density was then investigated.

The average BMP-2 concentration in the synovial fluid was 24.3 ± 6.9 pg/ml. The density of the anterior knee capsule was on average 136 ± 35 grey scale values. A linear correlation was shown between the BMP-2 concentration in the synovial fluid and the radiological density of the anterior joint capsule (R=0.84, p = 0.009).

We were able to show that there is a connection between BMP-2 concentration and soft-tissue density in arthrofibrosis after TKA. This opens up the possibility of conducting a prophylaxis against arthrofibrosis in risk patients by influencing the BMP-2 pathway.

Real-time detection of implant-associated neutrophil responses using a formyl peptide receptor-targeting NIR nanoprobe

Neutrophils play an important role in implant-mediated inflammation and infection. Unfortunately, current methods which monitor neutrophil activity, including enzyme measurements and histological evaluation, require many animals and cannot be used to accurately depict the dynamic cellular responses. To understand the neutrophil interactions around implant-mediated inflammation and infection it is critical to develop methods which can monitor in vivo cellular activity in real time. In this study, formyl peptide receptor (FPR)-targeting near-infrared nanoprobes were fabricated. This was accomplished by conjugating near-infrared dye with specific peptides having a high affinity to the FPRs present on activated neutrophils. The ability of FPR-targeting nanoprobes to detect and quantify activated neutrophils was assessed both in vitro and in vivo. As expected, FPR-targeting nanoprobes preferentially accumulated on activated neutrophils in vitro. Following transplantation, FPR-targeting nanoprobes preferentially accumulated at the biomaterial implantation site. Equally important, a strong relationship was observed between the extent of fluorescence intensity in vivo and the number of recruited neutrophils at the implantation site. Furthermore, FPR-targeting nanoprobes may be used to detect and quantify the number of neutrophils responding to a catheter-associated infection. The results show that FPR-targeting nanoprobes may serve as a powerful tool to monitor and measure the extent of neutrophil responses to biomaterial implants in vivo.

Identification of mammary epithelial cells subject to chronic oxidative stress in mammary epithelium of young women and teenagers living in USA: implication for breast carcinogenesis

Current knowledge of changes in the mammary epithelium relevant to breast carcinogenesis is limited to when histological changes are already present because of a lack of biomarkers needed to identify where such molecular changes might be ongoing at earlier during the of decades-long latent stages of breast carcinogenesis. Breast reduction tissues from young women and teenagers, representative of USA's high breast cancer incidence population, were studies using immunocytochemistry and targeted PCR arrays in order to learn whether a marker of chronic oxidative-stress [protein adducts of 4-hydroxy-2-nonenal (4HNE)] can identify where molecular changes relevant to carcinogenesis might be taking place prior to any histological changes. 4HNE-immunopositive (4HNE+) mammary epithelial cell-clusters were identified in breast tissue sections from most women and from many teenagers (ages 14-30 y) and, in tissues from women ages 17-27 y with many vs. few 4HNE+ cells, the expression of 30 of 84 oxidative-stress associated genes was decreased and only one was increased > 2-fold. This is in contrast to increased expression of many of these genes known to be elicited by acute oxidative-stress. The findings validate using 4HNE-adducts to identify where molecular changes of potential relevance to carcinogenesis are taking place in histologically normal mammary epithelium and highlight differences between responses to acute vs. chronic oxidative-stress. We posit that the altered gene expression in 4HNE+ tissues reflect adaptive responses to chronic oxidative-stress that enable some cells to evade mechanisms that have evolved to prevent propagation of cells with oxidatively-damaged DNA and to accrue heritable changes needed to establish a cancer.