Studies of the mechanism by which the mechanical failure of polymethylmethacrylate leads to bone resorption

The influence of biological DMARDs on aseptic arthroplasty loosening: a retrospective cohort study

OBJECTIVE

To investigate whether biological DMARDs affect the risk of aseptic loosening after total hip/knee arthroplasty (THA/TKA) in patients with RA.

METHODS

We retrospectively identified all patients suffering from RA who underwent THA/TKA at our academic centre between 2002 and 2015 and linked them with an existing prospective observational RA database at our institution. The risk of aseptic loosening was estimated using radiological signs of component loosening (RCL). A time-dependent Cox regression analysis was used to compare the risk of implant loosening between patients treated with traditional DMARDS and biological DMARDs, or alternately both over time.

RESULTS

A total of 155 consecutive total joint arthroplasties (TJAs) (103 TKA vs 52 THA) was retrospectively included in the study. Mean age at implantation was 59 ± 13 years. Mean follow-up time was 69 ± 43 months. Overall, 48 (31%) TJAs showed signs of RCL, with 28 (27.2%) RCLs occurring after TKA compared with 20 after THA (38.5%). A significant difference regarding the incidence of RCL between the traditional DMARDs group (39 cases of RCL, 35%) and the biological DMARDs group (nine cases of RCL, 21%) (P = 0.026) was observed using the log-rank test. This was also true when using a time-dependent Cox regression with therapy as well as arthroplasty location (hip vs knee) as variables (P = 0.0447).

CONCLUSION

Biological DMARDs may reduce the incidence of aseptic loosening after TJA in patients with RA compared with traditional DMARDs. This effect seems to be more pronounced after TKA than THA.

Pathogenesis, Evaluation, and Management of Osteolysis After Total Shoulder Arthroplasty

Radiographic osteolysis after total shoulder arthroplasty (TSA) remains a challenging clinical entity, as it may not initially manifest clinically apparent symptoms but can lead to clinically important complications, such as aseptic loosening. A thorough consideration of medical history and physical examination is essential to rule out other causes of symptomatic TSA—namely, periprosthetic joint infection—as symptoms often progress to vague pain or discomfort due to subtle component loosening. Once confirmed, nonoperative treatment of osteolysis should first be pursued given the potential to avoid surgery-associated risks. If needed, the current surgical options include glenoid polyethylene revision and conversion to reverse shoulder arthroplasty. The current article provides a comprehensive review of the evaluation and management of osteolysis after TSA through an evidence-based discussion of current concepts.

Nanoplastics affect the inflammatory cytokine release by primary human monocytes and dendritic cells

So far, the human health impacts of nano- and microplastics are poorly understood. Thus, we investigated whether nanoplastics exposure induces inflammatory processes in primary human monocytes and monocyte-derived dendritic cells. We exposed these cells in vitro to nanoplastics of different shapes (irregular vs. spherical), sizes (50-310 nm and polydisperse mixtures) and polymer types (polystyrene; polymethyl methacrylate; polyvinyl chloride, PVC) using concentrations of 30-300 particles cell^-1. Our results show that irregular PVC particles induce the strongest cytokine release of these nanoplastics. Irregular polystyrene triggered a significantly higher pro-inflammatory response compared to spherical nanoplastics. The contribution of chemicals leaching from the particles was minor. The effects were concentration-dependent but varied markedly between cell donors. We conclude that nanoplastics exposure can provoke human immune cells to secrete cytokines as key initiators of inflammation. This response is specific to certain polymers (PVC) and particle shapes (fragments). Accordingly, nanoplastics cannot be considered one homogenous entity when assessing their health implications and the use of spherical polystyrene nanoplastics may underestimate their inflammatory effects.

Pulsatile Lavage During Cementation of Total Knee Arthroplasty - Is Fixation Impaired? A Cadaver Study

BACKGROUND/AIM

Increasing economic pressure in modern healthcare necessitates an increase in efficiency in total knee arthroplasty (TKA) while maintaining high-quality outcomes. Removal of debris using pulsatile lavage (PL) during cement polymerization may considerably reduce the operative duration. However, water can penetrate the interface, resulting in impaired implant fixation. The aim of the present study was to investigate the impact of early-onset PL during bone cement polymerization on implant fixation and operative duration.

MATERIALS AND METHODS

Cemented implantation of tibial trays was performed in 20 fresh-frozen human tibiae from 10 donors in a matched-pair study design in two groups: 1) PL during cement polymerization; and 2) PL after completion of the polymerization process. The cement penetration depth was analysed by computed tomography (CT), and the pull-out force was measured to evaluate primary implant fixation. The duration of the procedure was recorded for both groups.

RESULTS

Comparable pull-out forces were observed in the experimental (2,213 N) and control groups (2,350 N; p=0.68). The mean depth of cement penetration was similar in both groups. PL during cement polymerization could decrease the operative duration by 10 min.

CONCLUSION

The application of PL during cement polymerization could significantly reduce operative duration and had no adverse effect on the mechanical fixation of the tibial component.

Osteolysis: A Literature Review of Basic Science and Potential Computer-Based Image Processing Detection Methods

Osteolysis is one of the most prominent reasons of revision surgeries in total joint arthroplasty. This biological phenomenon is induced by wear particles and corrosion products that stimulate inflammatory biological response of surrounding tissues. The eventual responses of osteolysis are the activation of macrophages leading to bone resorption and prosthesis failure. Various factors are involved in the initiation of osteolysis from biological issues, design, material specifications, and model of the prosthesis to the health condition of the patient. Nevertheless, the factors leading to osteolysis are sometimes preventable. Changes in implant design and polyethylene manufacturing are striving to improve overall wear. Osteolysis is clinically asymptomatic and can be diagnosed and analyzed during follow-up sessions through various imaging modalities and methods, such as serial radiographic, CT scan, MRI, and image processing-based methods, especially with the use of artificial neural network algorithms. Deep learning algorithms with a variety of neural network structures such as CNN, U-Net, and Seg-UNet have proved to be efficient algorithms for medical image processing specifically in the field of orthopedics for the detection and segmentation of tumors. These deep learning algorithms can effectively detect and analyze osteolytic lesions well in advance during follow-up sessions in order to administer proper treatments before reaching a critical point. Osteolysis can be treated surgically or nonsurgically with medications. However, revision surgeries are the only solution for the progressive osteolysis. In this literature review, the underlying causes, mechanisms, and treatments of osteolysis are discussed with the main focus on the possible computer-based methods and algorithms that can be effectively employed for the detection of osteolysis.

Zoledronic acid and teriparatide have a complementary therapeutic effect on aseptic loosening in a rabbit model

Background

Revisions are mainly caused by wear debris-induced aseptic loosening. How to effectively suppress debris-induced periprosthetic osteolysis has become an urgent problem. Both zoledronic acid and teriparatide can increase the bone mass around prostheses and increase the stability of prostheses. A hypothesis was proposed: the combination of the two drugs may have a better treatment effect than the use of either drug alone.

Methods

We created a rabbit model to study the effect and mechanism of the combination of zoledronic acid and teriparatide in the treatment of aseptic loosening. Thirty-two adult male New Zealand white rabbits were selected and treated with TKA surgery, and a titanium rod prosthesis coated evenly with micrometre-sized titanium debris was implanted into the right femoral medullary cavity. All rabbits were randomized into four groups (control group = 8, zoledronic acid group = 8, teriparatide group = 8, and zoledronic acid + teriparatide group = 8). All the animals were sacrificed in the 12th week, and X-ray analyses, H&E staining, Goldner-Masson trichrome staining, von Kossa staining, and RT-PCR and Western blotting of the mRNA and protein of OCN, OPG, RANKL and TRAP5b in the interface membrane tissues around the prostheses were immediately carried out.

Results

The results shown that both zoledronic acid and teriparatide could inhibit debris-induced peri-prosthetic osteolysis and promote new bone formation. Zoledronic acid was more capable of inhibiting osteoclast activation and peri-prosthetic osteolysis, while teriparatide was more capable of promoting osteoblast function and peri-prosthetic bone integration.

Conclusion

This research confirmed that the combination of zoledronic acid and teriparatide could prevent and treat aseptic loosening of the prosthesis more effectively. However, the safety of this combination and the feasibility of long-term application have not been ensured, and the clinical application requires further experiments and clinical research support.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04458-4.

Primary Total Knee Arthroplasty Performed Using High-Viscosity Cement is Associated With Higher Odds of Revision for Aseptic Loosening

BACKGROUND

Aseptic loosening (AL) is the most common reason for revision total knee arthroplasty (TKA). An association between high-viscosity cement (HVC) and AL has been suggested by small, uncontrolled, case series. This study sought to determine whether HVC use during primary TKA is independently associated with AL requiring revision.

METHODS

We retrospectively analyzed a prospectively collected institutional knee registry to identify all primary TKAs from January 2007 to December 2016. Patients with less than 2 years of follow-up were excluded. Cement type was divided into 2 groups: HVC and low-viscosity cement. Potential confounders including age, body mass index, preoperative diagnosis, antibiotics in the cement, and implant type were recorded. Multivariable logistic regression analysis was used to determine whether HVC is independently associated with revision for AL.

RESULTS

In total, 10,014 patients were included. Revision for AL was significantly higher in the HVC cohort (91/4790; 1.9%) vs the low-viscosity cement cohort (48/5224; 0.92%) (P < .001). Logistic regression demonstrated HVC to be independently associated with higher odds of revision for AL (odds ratio 2.26, 95% confidence interval 1.58-3.22, P < .001). Younger age was also associated with higher odds of revision for AL (odds ratio 0.96, 95% confidence interval 0.94-0.98, P < .001). Body mass index, gender, laterality, preoperative diagnosis, and antibiotics in the cement were not associated with revision for AL. Implant manufacturer, implant design, and cement brand all impacted the odds of undergoing revision for AL.

CONCLUSION

Although HVC is an attractive option for use in primary TKA, this appropriately controlled study demonstrates higher odds of revision for AL when using HVC with multiple different implant types.

Antibiotic-impregnated articulating cement spacer maintained for 7 years in situ for two-stage primary total knee arthroplasty: a case report

Background

Antibiotic-impregnated articulating cement spacers can maintain interim joint motion with the potential to enhance functional status and improve patient satisfaction. Articular surfaces with cement against cement have raised concerns regarding mechanical complications and cement debris during knee motion. However, long-term clinical conditions regarding these concerns are not well addressed.

Case presentation

We report a case in which articulating cement spacers were maintained in situ for 7 years. The patient had severe left knee pain with an ankylosing knee and severe tricompartmental arthritis due to tuberculous infection. We planned to perform one- or two-stage primary total knee arthroplasty (TKA), depending on the presence of infection. Persistent osteomyelitis was found intraoperatively. The second-stage TKA was delayed on the patient’s request. As the patient was satisfied with the improved knee function and pain relief after using articulating cement spacers. No symptom or sign that suggested recurrent infection or systemic toxicity was found during the 7-year follow-up. However, it seemed that the bone loss progressed insidiously. At the 7-year follow-up, a broken articulating cement spacer and medial femoral condylar fracture were found. The second-stage TKA was performed, and a considerable amount of bone loss surrounded by dense granulation tissue was observed intraoperatively. Excisional biopsy of the tissue revealed chronic foreign body reaction with infiltration of giant cells and macrophages.

Conclusion

Although the articular spacers were maintained for 7 years without major complications, regular observation of the development and progress of bone loss was required. Surgeons should take considerable bone loss into account during conversion TKA in patients with a prolonged retention of articulating cement spacers.

Application of a novel porous tantalum implant in rabbit anterior lumbar spine fusion model: in vitro and in vivo experiments

BACKGROUND

Some porous materials have been developed to enhance biologic fusion of the implants to bone in spine fusion surgeries. However, there are several inherent limitations. In this study, a novel biomedical porous tantalum was applied to in vitro and in vivo experiments to test its biocompatibility and osteocompatibility.

METHODS

Bone marrow-derived mesenchymal stem cells (BMSCs) were cultured on porous tantalum implant. Scanning electron microscope (SEM) and Cell Counting Kit-8 assay were used to evaluate the cell toxicity and biocompatibility. Twenty-four rabbits were performed discectomy only (control group), discectomy with autologous bone implanted (autograft group), and discectomy with porous tantalum implanted (tantalum group) at 3 levels: L3-L4, L4-L5, and L5-L6 in random order. All the 24 rabbits were randomly sacrificed at the different post-operative times (2, 4, 6, and 12 months; n = 6 at each time point). Histologic examination and micro-computed tomography scans were done to evaluate the fusion process. Comparison of fusion index scores between groups was analyzed using one-way analysis of variance. Other comparisons of numerical variables between groups were made by Student t test.

RESULTS

All rabbits survived and recovered without any symptoms of nerve injury. Radiographic fusion index scores at 12 months post-operatively between autograft and tantalum groups showed no significant difference (2.89 ± 0.32 vs. 2.83 ± 0.38, F = 244.60, P = 0.709). Cell Counting Kit-8 assay showed no significant difference of absorbance values between the leaching liquor group and control group (1.25 ± 0.06 vs. 1.23 ± 0.04, t = -0.644, P = 0.545), which indicated the BMSC proliferation without toxicity. SEM images showed that these cells had irregular shapes with long spindles adhered to the surface of tantalum implant. No implant degradation, wear debris, or osteolysis was observed. Histologic results showed solid fusion in the porous tantalum and autologous bone implanted intervertebral spaces.

CONCLUSION

This novel porous tantalum implant showed a good biocompatibility and osteocompatibility, which could be a valid biomaterial for interbody fusion cages.

Nanostructured titanium regulates osseointegration via influencing macrophage polarization in the osteogenic environment

Introduction

Fabricating nanostructured surface topography represents the mainstream approach to induce osteogenesis for the next-generation bone implant. In the past, the bone implant was designed to minimize host repulsive reactions in order to acquire biocompatibility. However, increasing reports indicate that the absence of an appropriate immune response cannot acquire adequate osseointegration after implantation in vivo.

Materials and methods

We prepared different topographies on the surface of titanium (Ti) specimens by grinding, etching and anodizing, and they were marked as polished specimen (P), specimen with nanotubes (NTs) in small diameters (NT-30) and specimen with NTs in large diameters (NT-100). We evaluated the ability of different topographies of the specimen to induce osteogenic differentiation of mice bone marrow mesenchymal stem cells (BMSCs) in vitro and to induce osseointegration in vivo. Furthermore, we investigated the effect of different topographies on the polarization and secretion of macrophages, and the effect of macrophage polarization on topography-induced osteogenic differentiation of mice BMSCs. Finally, we verified the effect of macrophage polarization on topography-induced osseointegration in vivo by using Cre*RBP-J^fl/fl mice in which classically activated macrophage was restrained.

Results

The osteogenic differentiation of mice BMSCs induced by specimen with different topographies was NT-100>NT-30>P, while the osseointegration induced by specimen with different topographies in vivo was NT-30>NT-100>P. In addition, specimen of NT-30 could induce more macrophages to M2 polarization, while specimen of P and NT-100 could induce more macrophages to M1 polarization. When co-culture mice BMSCs and macrophages on specimen with different topographies, the osteogenic differentiation of mice BMSCs was NT-30>NT-100≥P. The osseointegration induced by NT-100 in Cre*RBP-J^fl/fl mice was much better than that of wild type mice.

Conclusion

It is suggested that the intrinsic immunomodulatory effects of nanomaterials are not only crucial to evaluate the in vivo biocompatibility but also required to determine the final osseointegration. To clarify the immune response and osseointegration may be beneficial for the designation and optimization of the bone implant.

Disease-Associated Particulates and Joint Inflammation; Mechanistic Insights and Potential Therapeutic Targets

It is now well established that intra-articular deposition of endogenous particulates, such as osteoarthritis-associated basic calcium phosphate crystals, gout-associated monosodium urate crystals, and calcium deposition disease-associated calcium pyrophosphate crystals, contributes to joint destruction through the production of cartilage-degrading enzymes and pro-inflammatory cytokines. Furthermore, exogenous wear-debris particles, generated from prosthetic implants, drive periprosthetic osteolysis which impacts on the longevity of total joint replacements. Over the last few years, significant insight has been gained into the mechanisms through which these particulates exert their effects. Not only has this increased our understanding of the pathological processes associated with crystal deposition but it has also led to the identification of a number of therapeutic targets to treat particulate-associated disease. In this review, we discuss recent developments regarding the cellular events triggered by joint-associated particulates, as well as future directions in therapy for particulate-related arthropathies.

Effects of cobalt and chromium ions on lymphocyte migration

A T cell-mediated hypersensitivity reaction has been reported in some patients with CoCrMo-based implants. However, the role of cobalt and chromium ions in this reaction remains unclear. The objective of the present study was to analyze the effects of Co²⁺ and Cr³⁺ in culture medium, as well as the effects of culture supernatants of macrophages exposed to Co²⁺ or Cr³⁺ , on the migration of lymphocytes. The release of cytokines/chemokines by macrophages exposed to Co²⁺ and Cr³⁺ was also analyzed. The migration of murine lymphocytes was quantified using the Boyden chamber assay and flow cytometry, while cytokine/chemokine release by J774A.1 macrophages was measured by ELISA. Results showed an ion concentration-dependent increase in TNF-α and MIP-1α release and a decrease in MCP-1 and RANTES release. Migration analysis showed that the presence of Co²⁺ (8 ppm) and Cr³⁺ (100 ppm) in culture medium increased the migration of T lymphocytes, while it had little or no effect on the migration of B lymphocytes, suggesting that Co²⁺ and Cr³⁺ can stimulate the migration of T but not B lymphocytes. Levels of T lymphocyte migration in culture medium containing Co²⁺ or Cr³⁺ were not statistically different from those in culture supernatants of macrophages exposed to Co²⁺ or Cr³⁺ , suggesting that the effects of the ions and chemokines were not additive, possibly because of ion interference with the chemokines and/or their cognate receptors. Overall, results suggest that Co²⁺ and Cr³⁺ are capable of stimulating the migration of T (but not B) lymphocytes in the absence of cytokines/chemokines, and could thereby contribute to the accumulation of more T than B lymphocytes in periprosthetic tissues of some patients with CoCrMo-based implants. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:916-924, 2017.

Spectrum of Benign Articular and Periarticular Findings at FDG PET/CT

Whole-body fluorine 18 fluorodeoxyglucose (FDG) positron-emission tomography (PET)/computed tomography (CT) is performed primarily for oncologic indications; however, FDG uptake is not specific for malignancy. Herein we focus on causes of increased FDG uptake in and around joints, as lesions in these locations are commonly benign. A combination of primary intra-articular processes and osseous processes that may occur near the joint space will be discussed. Causes of intra-articular and periarticular increased FDG activity can be broadly divided into infectious, inflammatory, degenerative, and benign neoplastic categories. A familiarity with the full range of these processes is important to avoid misinterpretation, in turn decreasing unnecessary follow-up studies, procedures, and treatments. Differentiation from malignancy is often possible on the basis of a different level of FDG activity, divergent response to therapy, or differing changes over time, in comparison with a patient's known primary cancer. Recognizing an intra-articular lesion location can also be critical, as intra-articular metastases are rare. In some cases, benign FDG-avid articular and periarticular entities have a specific appearance at FDG PET/CT and a correct diagnosis may be made without any additional workup. In most other cases, comparison with prior studies and/or additional imaging can afford an accurate diagnosis. This review is meant to introduce the reader to a spectrum of benign FDG-avid articular and periarticular processes that may be encountered at oncologic FDG PET/CT to increase confidence and diagnostic accuracy. (©)RSNA, 2016.

Localized pigmented villonodular synovitis of the ankle: Expect the unexpected

BACKGROUND

We present the technique, results and discuss arthroscopic treatment of the localized form of pigmented villonodular synovitis (LPVNS) of the ankle.

METHODS

Medical records of five patients diagnosed and treated for ankle LPVNS with a minimum five-year followup were retrospectively reviewed. All patients were treated arthroscopically, altered synovial tissue was resected and a sample of tissue was sent for pathohistological examination for the definitive diagnosis.

RESULTS

No recurrence was noted at a mean followup of 6.5 years, both clinically and by MRI at one year postoperatively. Patients were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score, and an improvement was noted from an average score of 65.6 prior to treatment to 94.6 at final followup.

CONCLUSION

Considering the results of this case series, and the absence of complications, arthroscopy is a viable option for treating LPVNS of the ankle.

Nanomaterials: the next step in injectable bone cements

Injectable bone cements (IBCs) are biocompatible materials that can be used as bone defect fillers in maxillofacial surgeries and in orthopedic fracture treatment in order to augment weakened bone due to osteoporosis. Current clinically available IBCs, such as polymethylmethacrylate and calcium phosphate cement, have certain advantages; however, they possess several drawbacks that prevent them from gaining universal acceptance. New gel-based injectable materials have also been developed, but these are too mechanically weak for load-bearing applications. Recent research has focused on improving various injectable materials using nanomaterials in order to render them suitable for bone tissue regeneration. This article outlines the requirements of IBCs, the advantages and limitations of currently available IBCs and the state-of-the-art developments that have demonstrated the effects of nanomaterials within injectable systems.

In vitro response of human peripheral blood mononuclear cells to AISI 316L austenitic stainless steel subjected to nitriding and collagen coating treatments

Surface modification treatments can be used to improve the biocompatibility of austenitic stainless steels. In the present research two different modifications of AISI 316L stainless steel were considered, low temperature nitriding and collagen-I coating, applied as single treatment or in conjunction. Low temperature nitriding produced modified surface layers consisting mainly of S phase, which enhanced corrosion resistance in PBS solution. Biocompatibility was assessed using human peripheral blood mononuclear cells (PBMC) in culture. Proliferation, lactate dehydrogenase (LDH) levels, release of cytokines (TNF-α, IL-1β, IL-12, IL-10), secretion of metalloproteinase (MMP)-9 and its inhibitor TIMP-1, and the gelatinolytic activity of MMP-9 were determined. While the 48-h incubation of PBMC with all the sample types did not negatively influence cell proliferation, LDH and MMP-9 levels, suggesting therefore a good biocompatibility, the release of the pro-inflammatory cytokines was always remarkable when compared to that of control cells. However, in the presence of the nitrided and collagen coated samples, the release of the pro-inflammatory cytokine IL-1β decreased, while that of the anti-inflammatory cytokine IL-10 increased, in comparison with the untreated AISI 316L samples. Our results suggest that some biological parameters were ameliorated by these surface treatments of AISI 316L.

Interface abrasion between rough surface femoral stems and PMMA cement results in extreme wear volumes--a retrieval study and failure analysis

During the loosening cascade of cemented rough femoral stems, the destruction of the mantle and the production of cement and metal wear debris occur after the loss of constraint at the interface. Two-dimensional (2D) measurements (light microscopy based morphometry on fragments of mantles and vertical scanning interferometry of femoral stems) permitted mathematical 3D-extrapolations to estimate the wear volumes. Fragments of the cement mantles available lost volumes from 0.85 mm(3) to 494.10 mm(3) (median amount of bone cement wear = 178,426 mg). The harder metal surfaces lost between 1.459 mm(3) and 5.688 mm(3) of material (the median amount of metal wear per surface = 1.504 mg/100 mm(2)). Compared to the loss of material due to the fretting of stems, the abrasion of metal, and cement in defective cement mantles produced wear volumes sufficiently high to induce osteolysis. Though the design of the femoral stem and the handling of bone cement do not represent contemporary design and clinical practice, respectively, an extremely high number of joint replacements still in daily use may be impacted by this study because of possible predicted failures. Once the processes of fragmentation, abrasion, and osteolysis have been realized, the time until revision surgery should not be unduly prolonged.

Therapeutic potentials of naringin on polymethylmethacrylate induced osteoclastogenesis and osteolysis, in vitro and in vivo assessments

Wear debris associated periprosthetic osteolysis represents a major pathological process associated with the aseptic loosening of joint prostheses. Naringin is a major flavonoid identified in grapefruit. Studies have shown that naringin possesses many pharmacological properties including effects on bone metabolism. The current study evaluated the influence of naringin on wear debris induced osteoclastic bone resorption both in vitro and in vivo. The osteoclast precursor cell line RAW 264.7 was cultured and stimulated with polymethylmethacrylate (PMMA) particles followed by treatment with naringin at several doses. Tartrate resistant acid phosphatase (TRAP), calcium release, and gene expression profiles of TRAP, cathepsin K, and receptor activator of nuclear factor-kappa B were sequentially evaluated. PMMA challenged murine air pouch and the load bearing tibia titanium pin-implantation mouse models were used to evaluate the effects of naringin in controlling PMMA induced bone resorption. Histological analyses and biomechanical pullout tests were performed following the animal experimentation. The in vitro data clearly demonstrated the inhibitory effects of naringin in PMMA induced osteoclastogenesis. The naringin dose of 10 μg/mL exhibited the most significant influence on the suppression of TRAP activities. Naringin treatment also markedly decreased calcium release in the stimulated cell culture medium. The short-term air pouch mouse study revealed that local injection of naringin ameliorated the PMMA induced inflammatory tissue response and subsequent bone resorption. The long-term tibia pin-implantation mouse model study suggested that daily oral gavage of naringin at 300 mg/kg dosage for 30 days significantly alleviated the periprosthetic bone resorption. A significant increase of periprosthetic bone volume and regaining of the pin stability were found in naringin treated mice. Overall, this study suggests that naringin may serve as a potential therapeutic agent to treat wear debris associated osteolysis.

Titanium particles up-regulate the activity of matrix metalloproteinase-2 in human synovial cells

PURPOSE

Wear debris particle-induced osteolysis and subsequent aseptic loosening is one of the major causes of failure of total joint replacement. The purpose of this study was to investigate the effect of titanium implant material and inflammatory cytokines on human synovial cells and the development to osteolysis and aseptic loosening.

METHODS

This study investigated the effect of titanium implant material on the ECM-degraded MMP-2 in human synovial cells and analyzed the contribution of synovial cells in osteolysis and aseptic loosening.

RESULTS

When human synovial cells are exposed to titanium materials, MMP-2 activity is induced by 1.72 ± 0.14-fold with Ti disc and 3.95 ± 0.10-fold with Ti particles, compared with that of the controls, respectively. Inflammatory cytokines TNFα and IL-1β are also shown to induce MMP-2 activity by 3.65 ± 0.28-fold and 6.76 ± 0.28-fold, respectively. A combination of Ti particles and cytokines induces MMP-2 activities to a higher level (10.54 ± 0.45-fold). Inhibitors of various signal pathways involved in MMP-2 reverse Ti particle-induced MMP-2 activities.

CONCLUSIONS

Synovial cells surrounding the bone-prosthesis interface may contribute to production of MMP-2, and NFκB inhibitors may be explored as potential therapeutics to alleviate wear debris-induced osteolysis and aseptic loosening.

Histologic study of periprosthetic osteolytic lesions after AES total ankle replacement. A 22 case series

INTRODUCTION

Medium-term results for total ankle replacement (TAR) are in general satisfactory, but there is a high redo rate for periprosthetic osteolysis associated with the AES implant.

HYPOTHESIS

Comparing radioclinical findings and histologic analysis of implant revision procedure specimens can account for the elevated rate of osteolysis associated with the AES TAR implant.

MATERIAL AND METHOD

In a prospective series of 84 AES TAR implants (2003-2008), 25 underwent revision for osteolysis (including three undergoing revision twice) at a mean 59.8 months. Eight patients had hydroxyapatite (HA) coated models and the others had titanium-hydroxyapatite (Ti-HA) coatings. Radiographs were systematically analyzed on Besse's protocol and evolution was monitored on AOFAS scores. The 94 specimens taken for histologic analysis during revision were re-examined, focusing specifically on foreign bodies.

RESULTS

Macroscopically, no metallosis or polyethylene wear was found at revision. AOFAS global and pain scores fell respectively from 89.7/100 at 1 year postoperatively to 72.9 before revision and from 32.5/40 to 20.6/40, although global scores were unchanged in 25% of patients. Radiologically, all patients showed tibial and talar osteolytic lesions, 45% showed cortical lysis and in 25% the implant had collapsed into the cysts. All specimens showed macrophagic granulomatous inflammatory reactions in contact with a foreign body; the cysts showed necrotic remodeling. Some of the foreign bodies could be identified on optical histologic examination with polyethylene in 95% of the specimens and metal in 60% (100% of HA-coated models and 33.3% of Ti-HA-coated models). Unidentifiable material was associated: a brownish pigment in Ti-HA-coated models (33.3%) and flakey bodies in 44.4% of the HA-coated models and 18.2% of the Ti-HA-coated models.

DISCUSSION

The phenomenon of periprosthetic osteolysis is still poorly understood, although implant wear debris seems to be implicated. All the patients with HA-coated implants with modular tibial stem had metal particles in the tissue around the implant, although their exact nature could not be determined. The double-layer Ti-HA coating may induce delamination by fretting while the biological bone anchorage is forming.

LEVEL OF EVIDENCE

Prospective cohort study - Level IV.

In vitro macrophage response to nanometer-size chromium oxide particles

An increasing number of studies have reported adverse tissue reactions around metal-on-metal (MM) hip implants. However, the origin and mechanisms of these reactions remain unclear. Moreover, the biological effects of nanometer-size chromium oxide particles, the predominant type of wear particles produced by MM implants, remain mostly unknown. The purpose of this study was to analyze the cytotoxic effects of clinically relevant nanometer-size chromium oxide particles on macrophage response in vitro. J774.A1 macrophages were cultured with either 60 nm or 700 nm commercially available Cr2 O3 particles at different concentrations. Two different particle sizes were analyzed to evaluate potential volume effects. Cell mortality was analyzed by light microscopy, flow cytometry (annexin V-fluorescein isothiocyanate and propidium iodide assay), and using a cell death detection enzyme-linked immunosorbant assay (ELISA). Tumor necrosis factor alpha (TNF-α), monocyte chemotactic protein-1 (MCP-1), and macrophage inflammatory protein-1 alpha (MIP-1α) release was measured by ELISA, and gene expression was analyzed by quantitative real-time PCR. Results showed that, at high concentrations, Cr2 O3 particles of both sizes can be cytotoxic, inducing significant decreases in total cell numbers and increases in necrosis. Results also suggested that these effects were dependent on particle volume. However, TNF-α, MCP-1, and MIP-1α cytokine release and gene expression remained low. Overall, this study demonstrates that nanometer-size particles of Cr2 O3 , a stable form of chromium oxide ceramic, have rather low cytotoxic effects on macrophages. Therefore, these particles may not be the main culprit in the initiation of the inflammatory reaction in MM periprosthetic tissues. However, other parameters (e.g., potential intracellular damage) remain to be investigated.

Surface modification of fiber reinforced polymer composites and their attachment to bone simulating material

The purpose of this study was to investigate the effect of fiber orientation of a fiber-reinforced composite (FRC) made of poly-methyl-methacrylate (PMMA) and E-glass to the surface fabrication process by solvent dissolution. Intention of the dissolution process was to expose the fibers and create a macroporous surface onto the FRC to enhance bone bonding of the material. The effect of dissolution and fiber direction to the bone bonding capability of the FRC material was also tested. Three groups of FRC specimens (n = 18/group) were made of PMMA and E-glass fiber reinforcement: (a) group with continuous fibers parallel to the surface of the specimen, (b) continuous fibers oriented perpendicularly to the surface, (c) randomly oriented short (discontinuous) fibers. Fourth specimen group (n = 18) made of plain PMMA served as controls. The specimens were subjected to a solvent treatment by tetrahydrofuran (THF) of either 5, 15 or 30 min of time (n = 6/time point), and the advancement of the dissolution (front) was measured. The solvent treatment also exposed the fibers and created a surface roughness on to the specimens. The solvent treated specimens were embedded into plaster of Paris to simulate bone bonding by mechanical locking and a pull-out test was undertaken to determine the strength of the attachment. All the FRC specimens dissolved as function of time, as the control group showed no marked dissolution during the study period. The specimens with fibers along the direction of long axis of specimen began to dissolve significantly faster than specimens in other groups, but the test specimens with randomly oriented short fibers showed the greatest depth of dissolution after 30 min. The pull-out test showed that the PMMA specimens with fibers were retained better by the plaster of Paris than specimens without fibers. However, direction of the fibers considerably influenced the force of attachment. The fiber reinforcement increases significantly the dissolution speed, and the orientation of the glass fibers has great effect on the dissolving depth of the polymer matrix of the composite, and thus on the exposure of fibers. The glass fibers exposed by the solvent treatment enhanced effectively the attachment of the specimen to the bone modeling material.

Periprosthetic aseptic osteolysis in total ankle replacement: cause and management

Osteolysis is the loss of bone secondary to a pathologic process and remains the most common cause of failure of total ankle replacement. Friction at the bearing surface results in the generation of abraded wear debris of polyethylene. These activate a biologic cascade that may result in significant bone loss and subsequent loss of fixation of the prosthesis. Revision surgery must address this loss of bone and may be achieved through either bone grafting or use of appropriate revision prosthesis components.

Cytokine secretion from human peripheral blood mononuclear cells cultured in vitro with metal particles

The failure of implanted medical devices can be associated with changes in the production of cytokines by cells of the immune system. Cytokines released by peripheral blood mononuclear cells upon contact with metal particles were quantified to understand their role in implantation intergration and their importance as messengers in the recruitment of T-lymphocytes at the implantation site. Opsonization was utilised to understand the influence of serum proteins on particle-induced cytokine production and release. Different metal compositions were used in the particulate format, Titanium (Ti), Titanium alloy (Ti6Al4V), and Stainless Steel 316L (SS), and were cultured in vitro with a mixed population of monocytes/macrophages and lymphocytes. The cells were also exposed to an exogenous stimulant mixture of phytohemagglutinin-P and interferon-gamma (IFN-γ) and opsonized particles with human serum. Interleukins, IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IFN-γ, and tumor necrosis factor-alpha (TNF-α) were investigated using enzyme-linked immunosorbent assay as they are an indicator of the inflammation evoked by particulate metals. It has been experimentally evidenced that metal particles induced higher amounts of IL-6 and IL-1 but very low amounts of TNF-α. T-lymphocyte activation was evaluated by the quantification of IL-2 and IFN-γ levels. The results showed that nonopsonized and opsonized metal particles did not induce the release of increased levels of IL-2 and IFN-γ.

Haemocompatibility of titanium and its alloys

This review outlines the current understanding of the interactions of titanium and its alloys with blood components, and the ways in which surface modification techniques can be used to alter the surface physicochemical and topographical features that determine blood-material interactions. Surface modification of the spontaneously formed titanium oxide surface layer is a highly attractive means of improving haemocompatibility without forgoing the advantageous mechanical and physical properties of titanium and its alloys. A number of surface modification techniques and treatment processes are discussed in the context of enhancing the haemocompatibility of titanium and its alloys, with a view to optimising the clinical efficacy of blood-contacting devices and materials.

MMP-9 inhibition suppresses wear debris-induced inflammatory osteolysis through downregulation of RANK/RANKL in a murine osteolysis model

Wear debris-induced osteolysis in periprosthetic tissue with aseptic loosening is a serious problem after total joint arthroplasty. Matrix metalloproteinase-9 (MMP-9) is expressed in osteoclast cells that surround loosening peri-implant tissue, but the molecular mechanism of MMP-9 action in wear debris-induced osteolysis remains ambiguous. We used a murine osteolysis model to examine the hypothesis that administration of an MMP-9 inhibitor reduces the expression of receptor activator of nuclear factor-κB (RANK) and nuclear factor-κB ligand (RANKL) and, thereby, suppressesdebris-induced inflammatory osteolysis. Experiments were performed in 3 groups of 15 mice: a control, a titanium (Ti) and a Ti plus tetracycline group. To provoke inflammatory osteolysis, calvarial bone was implanted from syngeneic littermates, followed by injection of Ti particles into established air pouches for all groups except the control. Tetracycline was administered daily by intraperitoneal (i.p.) injection, and PBS was administered by i.p. injection to the control and Ti groups. Mice were sacrificed 14 days after bone-Ti implantation. Pouch membranes with the intact bone implants were collected for histological and molecular analysis. Tetracycline had minimum effect on the expression of MMP-9 and tumor necrosis factor-α (TNF-α) but it decreased gene activation and inhibited the expression of RANK and RANKL, thereby inhibiting Ti-particle-induced inflammatory osteolysis. Tetracycline decreased the number of tartrate-resistant acid phosphatase (TRAP)-positive cells in the pouch tissues. Our results in the murine osteolysis model suggest that through the downregulation of RANK/RANKL, tetracycline significantly inhibits debris-induced inflammatory osteolysis. Its use in clinical practice may help prevent complications experienced by patients who have undergone total joint arthroplasty.

Current concepts in osteolysis

The most frequent cause of failure after total hip replacement in all reported arthroplasty registries is peri-prosthetic osteolysis. Osteolysis is an active biological process initiated in response to wear debris. The eventual response to this process is the activation of macrophages and loss of bone. Activation of macrophages initiates a complex biological cascade resulting in the final common pathway of an increase in osteolytic activity. The biological initiators, mechanisms for and regulation of this process are beginning to be understood. This article explores current concepts in the causes of, and underlying biological mechanism resulting in peri-prosthetic osteolysis, reviewing the current basic science and clinical literature surrounding the topic.

Complication of cemented vertebra after kyphoplasty in osteoporotic compression fracture

The reported case is of a postmenopausal woman with kyphoplasty for an L1 osteoporotic compression fractures (OCF) presenting with progressive kyphosis and paraparesis that developed with no history of other traumas. Serial radiographs and computed tomography were performed, followed by magnetic resonance (MR) imaging. On serial radiographs, local kyphosis and neurologic deficit progressed with collapse of the cemented vertebra. MR scan and histologic examination diagnosed avascular necrosis (AVN). The symptoms resolved after posterior vertebral column resection of the collapsed cemented vertebral body and correction of the deformity. Although kyphoplasty is a simple and safe procedure for the management of pain in OCFs, careful follow-up is required as collapse of the cemented vertebra may be an AVN of the cemented vertebra and lead to neurologic deficit over time.

Actin and ERK1/2-CEBPβ signaling mediates phagocytosis-induced innate immune response of osteoprogenitor cells

Wear particles at the host bone-implant interface are a major challenge for successful bone implant arthoplasties. Current understanding of aseptic loosening consists of macrophage-mediated inflammatory responses and increasing osteoclastogenesis, which lead to an imbalance between bone formation and resorption. Despite its significant role in bone regeneration and implant osteointegration, the osteoprogenitor response to wear particles has been examined recent years. More specifically, the intracellular mechanism of osteoprogenitor mediated inflammation has not been fully elucidated. In this study, we examined the role of osteoprogenitors and the cellular mechanism by which metal wear particles elicit an inflammatory cascade. Through both in vivo and in vitro experiments, we have demonstrated that osteoprogenitor cells are capable of initiating inflammatory responses by phagocytosing wear particles, which lead to subsequent accumulation of macrophages and osteoclastogenesis, and the ERK_CEBP/β intracellular signaling is a key inflammatory pathway that links phagocytosis of wear particles to inflammatory gene expression in osteoprogenitors. AZD6244 treatment, a potent inhibitor of the ERK pathway, attenuated particle mediated inflammatory osteolysis both in vivo and in vitro. This study advances our understanding of the mechanisms of osteoprogenitor-mediated inflammation, and provides further evidence that the ERK_CEBP/β pathway may be a suitable therapeutic target in the treatment of inflammatory osteolysis.

Evaluation of a fiber reinforced drillable bone cement for screw augmentation in a sheep model--mechanical testing

We evaluated the mechanical properties of a novel fiber reinforced calcium phosphate at time zero and after 12 weeks in vivo using a sheep long bone osteotomy model. Time zero data were obtained and compared by pullout testing of 4.5 mm bone screws from bone proper and overdrilled defects of 4.5 and 8 mm diameter. Defects were augmented with: polymethylmethacrylate (PMMA), calcium phosphate, and fiber reinforced calcium phosphate using cadaveric sheep tibiae. Twelve-week data were obtained from explanted tibiae of sheep that underwent unilateral tibial osteotomy surgery repaired with a locking compression plate. The most distal hole was overdrilled to 4.5 or 8 mm diameter, filled with fiber reinforced cement, drilled, tapped and a 4.5 mm screw was placed. Screw holding strength at t= 0 was significantly higher for reinforced when compared to nonreinforced cement, but not different from bone or PMMA in 4.5 mm defects. There was no difference in pullout strength for the 8 mm defect data. After 12 weeks fiber reinforced pullout strength increased by 45% and 8.9% for 4.5 and 8 mm defects, respectively, when compared to t= 0 testing. Fiber reinforced calcium phosphate bone cement can be drilled and tapped to support orthopedic hardware for trauma applications.

Radiographic and histopathologic analysis of osteolysis after total shoulder arthroplasty

HYPOTHESIS

This study analyzed clinical, radiographic, and histologic data from failed total shoulder arthroplasties (TSAs) to determine factors associated with osteolysis.

MATERIALS AND METHODS

From 1985 to 2005, 52 patients (mean age, 61.6 years) underwent revision TSA at a single institution at a mean of 4.3 years after their index surgery. Patients were retrospectively assigned to 2 cohorts based on the presence (n = 10) or absence (n = 42) of osteolysis around their implants on the last prerevision surgery radiographs. Clinical information, associated histopathology from tissues obtained at revision surgery, and polyethylene wear data from the retrieved glenoid components were compared between groups.

RESULTS

In the osteolysis group, 20% had screw fixation compared with 2.5% without osteolysis (P = .039). The radiolucency score was significantly higher in the osteolysis group: 12.7 +/- 2.0 vs 8.7 +/- 3.7 (P = .003). Wear analysis of the osteolysis group demonstrated significant increases in third-body particles compared with those implants without osteolysis (P = .004). Histology available from retrieved implants demonstrated particulate debris in 62% of patients with osteolytic lesions vs 67% without osteolytic lesions (P > .05).

DISCUSSION

Significant differences were found in patients with osteolytic lesions compared with patients undergoing TSA revision surgery without such lesions, specifically with regard to glenoids that used adjuvant screw fixation, the presence of increased radiolucent lines, and an abundance of third-body wear. No significant differences were found in particulate wear debris despite the prevailing notion that osteolysis is associated with particulate debris from implant wear.

CONCLUSION

Screw fixation and third-body wear were associated with osteolysis after TSA.

Ectopic expression of macrophage scavenger receptor MARCO in synovial membrane-like interface tissue in aseptic loosening of total hip replacement implants

Macrophage receptor with collagenous structure (MARCO) is a scavenger receptor with a very limited expression in healthy tissues. It was hypothesized that foreign body wear debris induces it to participate in handling of implant-derived particles in human synovial membrane-like tissue around aseptically loosening total hip replacement implants. A DNA microarray study showed that MARCO was upregulated in human monocytes by polymethyl methacrylate particles in cell culture. MARCO mRNA and protein were strongly expressed in numerous CD68 positive macrophages and foreign body giant cells in interface membrane lining and stroma around cemented implants, but was only present in a few cells in synovial membrane from osteoarthritis patients. A 65-kDa MARCO-reactive band was only found in interface tissue extracts. This is the first work to show upregulation of MARCO mRNA by foreign bodies in vitro. This is paralleled in vivo as MARCO mRNA and protein were over-expressed in chronic foreign body synovitis. As scavenger receptor MARCO apparently participates in handling of wear particles, which due to their nondegradable, irritating nature initiate/perpetuate foreign body inflammation, and peri-implant osteolysis.

Mechanical performance and in vivo tests of an acrylic bone cement filled with bioactive sepia officinalis cuttlebone

To promote osteointegration, bioactive cuttlebone particles containing collagen were used to fill an acrylic cement, varying filler concentration (0-50 wt%). Cuttlebone was characterized by X-ray diffraction, plasma atomic emission and FT-IR. Mechanical properties of the filled cement were determined following ASTM procedures, included stress-strain, compression, bending, and fracture toughness tests. For in vivo tests, three groups of seven adult healthy rabbits were prepared to make an implant in the parietal bone of each one. For such groups (I-III), the amount of filler in the cement was 0, 10 and 30 wt%, respectively. Mechanical results for the composites complied with norm requirements. However, as mechanical performance for composite with 50 wt% of filler decreased significantly, for the in vivo tests, such composite was excluded. In vivo tests showed that three implants of group I were loosely attached to the parietal bone, whereas all the implants made with cement containing cuttlebone particles (groups II and III) were firmly attached to the parietal bone, indicating osteointegration. These results clearly show the potential of this type of bioactive filler to be used for medical applications.

A novel murine model of orthopaedic wear‐debris associated osteolysis

OBJECTIVE

To develop a mouse model of bone resorption to quantitatively evaluate wear-debris induced osteolysis.

METHODS

Air pouches were established on the back of BALB/c mice, followed by the surgical introduction of a section of femur or calvaria from a syngeneic mouse donor. One group of bone-implanted pouches was stimulated with ultra-high molecular weight polyethylene (UHMWPE) debris, and the remaining bone-implanted pouches received saline alone as controls. The tissues were harvested at 2, 7, and 14 days after bone implantation for molecular and histological analyses.

RESULTS

Marked inflammatory responses (thicker membrane and increased cellular infiltration) were observed in UHMWPE-stimulated pouches, compared with the saline control. Intensive tartrate-resistant acid phosphatase (TRAP) staining was identified in the UHMWPE-stimulated pouches, especially at the attachment site of inflammatory tissue with implanted bone, where active osteolysis occurred. Image analysis showed that the bone collagen loss was closely related to the amount of UHMWPE within the tissue, and was most prevalent at the contact site of bone with inflammatory tissue. UHMWPE stimulation also significantly increased the release of free calcium into the pouch fluids.

CONCLUSION

This model demonstrates a sensitive, rapid, and reproducible method for studying wear-debris induced osteolysis seen in patients with aseptic loosening.

Hip arthroplasty. Part 2: normal and abnormal radiographic findings

This review addresses the normal and abnormal radiographic findings that can be encountered during the follow-up of patients with total hip arthroplasty (THA). The relative significance of different patterns of radiolucency, bone sclerosis, and component position is discussed. The normal or pathological significance of these findings is correlated with design, surface, and fixation of the prosthetic components. It is essential to have a good knowledge of expected and unexpected radiological evolution according to the different types of prostheses. This paper emphasizes the importance of serial studies compared with early postoperative radiographs during follow-up in order to report accurately any sign of prosthetic failure and trigger prompt specialist referral. Basic technical guidelines and schedule recommendations for radiological follow-up are summarized.

Primary ceramic-on-ceramic total hip replacement versus metal-on-metal hip resurfacing in young active patients

The purpose of this study was to compare clinical outcomes between ceramic-on-ceramic total hip replacement and metal-on-metal hip resurfacing arthroplasty in comparable groups of young active patients at a 3- to 6-year follow-up. The first 250 patients (mean age, 49.54 years) of a series of 930 resurfacing arthroplasties were compared clinically and functionally with a series of 190 patients (mean age, 46.76 years) with ceramic-on-ceramic uncemented total hip prostheses. The total Harris hip score was 97.9 in the resurfacing group vs 92.1 in the ceramic group. In the resurfacing group, 60.71% had a strenuous activity level vs 30.43% in the ceramic group.

Radiographic and pathological stages of the changes at the bone-cement interface: an in-vivo experimental study

INTRODUCTION

Chemical and physical effects of cementation cause radiographic and histological changes at bone-cement interface. These changes can be of interest in the assessment of the residual lesions and subsequent recurrences after local resection and cementation of local aggressive tumours.

AIM

The aim of the study was to evaluate the evolution and determine the stages of the changes that occur at the bone-cement interface after cementation of cavitary lesions.

MATERIAL AND METHODS

We operated on 16 hind legs of 8 sheep (Ovies Aries) under general anaesthesia (Xylasin HCl, Ketamin HCl and Forane). A bone cavity of 12 cm(3) was produced by curettage of the distal femoral condyle and was filled with cement. Control radiographs were taken at 2 days; 3, 6 and 12 weeks, and again at 6 months. One sheep each time was killed after second day and sixth month and two sheep each time after the third, sixth and 12th week and the specimens underwent pathological examination.

RESULTS

After the first 3 weeks, a reactive fibrous membrane was detected on pathological examinations. This membrane consisted of granulation tissue, necrotic bone and bone marrow, which were replaced gradually by fibrous tissue. The radiographic revelation of this fibrous membrane was a radiolucent zone of 0.5-1.5 mm at 3 weeks. A Sclerotic rim appeared around this radiolucent zone at 6 weeks. With new bone formation the fibrous membrane disappeared at 3 months. This was seen on radiographs as the replacement of the radiolucent zone by a sclerotic ring of 0.5-2 mm. This sclerotic ring disappeared at 6 months, when a diffuse sclerosis and cortical bone thickening was detected on radiographs.

DISCUSSION

According to our findings we suggest to consider the pathological processes at the bone-cement interface in 3 phases: (1) Reactive phase (first 3 weeks); (2) Resorption phase (3-6 weeks), and (3) Formation phase (6 weeks to 6 months). We have distinguished five different radiographic stages: Stage 1-Early stage with no apparent zone (first 3 weeks); Stage 2-Radiolucent zone (3-6 weeks); Stage 3-Radiolucent zone with a sclerotic rime (6 weeks to 3 months); Stage 4-sclerotic ring (after 3 months) and Stage 5-Diffuse cortical thickening (after 6 months). Determining the phases of tissue reaction after cementation and its radiographic revelation will ease the diagnosis of residual lesions and subsequent recurrences after local resection and cementation of local aggressive tumors.

Calcium-phosphate and polymethylmethacrylate cement in long-term outcome after kyphoplasty of painful osteoporotic vertebral fractures

STUDY DESIGN

A comparative prospective trial evaluating 3-year outcome.

OBJECTIVE

To compare clinical and morphologic outcomes as well as follow-up fractures after kyphoplasty of painful osteoporotic vertebral fractures with calcium-phosphate (CaP) cement (group 1) and with polymethylmethacrylate (PMMA)-cement (group 2).

SUMMARY OF BACKGROUND DATA

CaP cements seem to be an alternative material for usage in kyphoplasty of vertebral fractures. CaP cements are biodegradable and replaceable by newly formed bone after implantation. Concerns have been raised with regard to the stability of resorbable CaP-cements after implantation into vertebrae post kyphoplasty. Calcibon is a possible CaP cement, which exhibited adequate stability in short-term observations.

MATERIALS AND METHODS

Kyphoplasty was performed in 40 consecutive patients with primary osteoporosis and painful vertebral fractures, 20 received CaP-cement, 20 were treated with PMMA-cement. All patients received a pharmacological antiosteoporosis treatment (1000 mg calcium, 1000 IU vitamin D3, and oral aminobisphosphonate), pain medication, and physiotherapy. Pain (visual analog scale [VAS]; range, 0-100), mobility (EVOS-score; range, 0-100) and radiomorphologic measurements were assessed at baseline and after 6, 12, and 36 months.

RESULTS

There were no statistically significant differences between the CaP and PMMA-cement group regarding VAS-scores, EVOS-scores, or height-restoration at any time point. Furthermore, there was no significant difference in the occurrence of vertebral follow-up fractures between both groups during the 3-year follow-up period.

CONCLUSION

CaP cement, e.g., Calcibon, is as effective and safe as conventional PMMA-cement with regard to immediate and sustained pain reduction and improvement of mobility after kyphoplasty of patients with painful osteoporotic vertebral fractures. CaP cement has the potential of being resorbed and replaced by newly formed bone tissue; thus, it seems to be a promising alternative for PMMA also in younger patients with painful vertebral fractures.

Alternative acrylic bone cement formulations for cemented arthroplasties: present status, key issues, and future prospects

All the commercially available plain acrylic bone cement brands that are used in cemented arthroplasties are based on poly (methyl methacrylate) and, with a few exceptions, have the same constituents. It is well known that these brands are beset with many drawbacks, such as high maximum exotherm temperature, lack of bioactivity, and volumetric shrinkage upon curing. Furthermore, concerns have been raised about a number of the constituents, such as toxicity of the activator (N,N,dimethyl-p-toluidine) and possible involvement of the radiopacifier (BaSO(4) or ZrO(2) particles) in third-body wear. Thus, over the years, many research efforts have been expended to address these drawbacks, culminating in a large number of alternative formulations, which may be grouped into 16 categories. Although there are a number of reviews of the large literature that now exists on these formulations, each covers only some of the categories and none contains a detailed discussion of the germane issues. The objective of the present work, therefore, was to present a comprehensive and critical review of the whole field. In addition to succinct descriptions of the cements in each category, there are explicative summaries of literature reports, a detailed discussion of several key issues surrounding the potential for use of these cements in cemented arthroplasties, and a presentation of numerous ideas for future studies.

Human macrophage response to UHMWPE, TiAlV, CoCr, and alumina particles: analysis of multiple cytokines using protein arrays

Aseptic loosening of total joint replacements is believed to be initiated by a macrophage response to prosthetic wear debris. To better characterize the early response to clinically relevant wear debris, we challenged primary human macrophages from four donors with ultra high molecular weight polyethylene (UHMWPE), TiAlV, CoCr, and alumina particles. After a 24-h culture, protein arrays were used to quantify the secretion of 30 different cytokines and chemokines. Macrophages secreted detectable levels of nine mediators in culture: Interleukin-1alpha (IL-1alpha), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, MCP-1, IL-8, IL-6, GM-CSF, IL-10, and IL-12p40. TiAlV particles were the most stimulatory, causing 5- to 900-fold higher cytokine expression compared with nonstimulated cells and uniquely eliciting high levels of IL-1alpha, IL-6, IL-10, and GM-CSF. CoCr and alumina were mildly stimulatory and typically elicited two- to fivefold greater levels than nonstimulated cells. Surprisingly, UHMWPE did not elicit a significant increase in cytokine release. Our data suggests that IL-1alpha, TNF-alpha, IL-1beta, and MCP-1 are the primary initiators of osteolysis and implicates metallic debris as an important trigger for their release.

Statins attenuate polymethylmethacrylate-mediated monocyte activation

BACKGROUND

Periprosthetic osteolysis precipitates aseptic loosening of components, increases the risk of periprosthetic fracture and, through massive bone loss, complicates revision surgery and ultimately is the primary cause for failure of joint arthroplasty. The anti-inflammatory properties of HMG-CoA reductase inhibitors belonging to the statin family are well recognized. We investigated a possible role for status in initiating the first stage of the osteolytic cycle, namely monocytic activation.

METHODS

We used an in vitro model of the human monocyte/macrophage inflammatory response to poly-methylmethacrylate (PMMA) particles after pretreat-ing cells with cerivastatin, a potent member of the statin family. Cell activation based upon production of TNF-alpha and MCP-1 cytokines was analyzed and the intracellular Raf-MEK-ERK signal transduction pathway was evaluated using western blot analysis, to identify its role in cell activation and in any cerivastatin effects observed.

RESULTS

We found that pretreatment with cerivastatin significantly abrogates the production of inflammatory cytokines TNF-alpha and MCP-1 by human monocytes in response to polymethylmethacrylate particle activation. This inflammatory activation and attenuation appear to be mediated through the intracellular Raf-MEK-ERK pathway.

INTERPRETATION

We propose that by intervening at the upstream activation stage, subsequent osteoclast activation and osteolysis can be suppressed. We believe that the anti-inflammatory properties of statins may potentially play a prophylactic role in the setting of aseptic loosening, and in so doing increase implant longevity.

Are there biological markers of wear?

Potential systemic markers of implant wear include products of the wear process (particles and ions) and mediators of the inflammatory reaction that can be induced by wear. Ions from polymers used in arthroplasty are not specific, but high metal ion levels may help identify patients with unexpectedly high wear of metal-on-metal implants. The kinetics of ion production, transport, and excretion are complex, however, so it is currently difficult to interpret the significance of mild elevations in metal ions. Indices of bone turnover (eg, collagen fragments) and mediators involved in the inflammatory reaction to particles (eg, osteoprotegerin, RANKL, interleukins) may be associated with osteolysis, but systemic disorders (eg, osteoarthritis) and the use of medications that influence bone remodeling limit the predictive value of these analytes with respect to the consequences of implant wear. Using genomic and proteomic methods to measure multiple analytes offers promise, but the challenge is to identify markers specifically associated with wear that are not elevated by other conditions that often coexist in this patient population.

Hypersensitivity to benzoyl peroxide in a cemented total knee arthroplasty: cement allergy

A small but significant proportion of cemented total knee arthroplasties develop aseptic loosening. Polyethylene debris is unlikely to be the cause in the small subgroup that experiences early loosening. Allergy to polymethylmethacrylate bone cement or its constituents has been reported in several different industries and in dentistry, dermatology, and joint arthroplasty. Although allergy to polymethylmethacrylate bone cement or its constituents is unusual, the possibility of a systemic inflammatory response and consequent pain and loosening must be considered. We report a case history of a patient who developed a systemic reaction and intractable pain after a total knee arthroplasty who was subsequently shown to be hypersensitive to the benzoyl peroxide component of bone cement.

Biomechanical Evaluation of Cervical Intervertebral Plug Stabilization in an Ovine Model

OBJECTIVE

(1) To determine the biomechanical stability of cervical spinal segment C5-C6 after ventral slot (VS) decompression and distraction-stabilization by a modified polymethylmethacrylate (PMMA) intervertebral plug technique (IVP) in an ovine model. (2) To determine if the distraction of the disk space is maintained after VS-IVP, and the frequency of bony intervertebral union.

STUDY DESIGN

Experimental in vivo study in an ovine model with an in vitro control study.

ANIMALS

Adult (>2 years age), intact sheep (n=18).

METHODS

Ten sheep had VS/IVP surgery of C5-6 with computed tomography (CT) images obtained immediately before and after surgery, as well as 8 (n=10) and 24 (n=5) weeks postoperatively. Cervical spines harvested 8 weeks (8-week group; n=5) and 24 weeks (24-week group; n=5) after surgery had three-dimensional (3D) flexibility tests in flexion-extension, axial rotation, and lateral bending. Image data was analyzed qualitatively and quantitatively in 3D. Eight ovine cervical spines served as controls and had biomechanical testing in intact condition (n=5) and after in vitro VS/IVP (n=5).

RESULTS

Significantly decreased range of motion (ROM) was noted in all loading modes when comparing in vitro operated spines and the 24-week group to intact spines. The 8-week group was not significantly different from the intact group, except in lateral bending. Quantitative CT analysis of treatment groups showed progressive disk space collapse and ventral implant migration. Intervertebral bony union did not occur.

CONCLUSION

Biomechanical stability was obtained immediately after VS/IVP surgery, but ROM at 8 weeks was not different from intact spines. However, at 24 weeks, the operated level had regained stability similar to the immediate postoperative level. Distraction of the disk space was not maintained and bony union did not occur in this ovine model of VS/IVP.

CLINICAL RELEVANCE

In clinical situations requiring constant increased stability of cervical segments for an extended time, more rigid stabilization techniques are required.