Nonsurgical management of osteolysis: challenges and opportunities

Aseptic loosening around total joint replacement in humans is regulated by miR-1246 and miR-6089 via the Wnt signalling pathway

BACKGROUND

Total joint replacement for osteoarthritis is one of the most successful surgical procedures in modern medicine. However, aseptic loosening continues to be a leading cause of revision arthroplasty. The diagnosis of aseptic loosening remains a challenge as patients are often asymptomatic until the late stages. MicroRNA (miRNA) has been demonstrated to be a useful diagnostic tool and has been successfully used in the diagnosis of other diseases. We aimed to identify differentially expressed miRNA in the plasma of patients with aseptic loosening.

METHODS

Adult patients undergoing revision arthroplasty for aseptic loosening and age- and gender-matched controls were recruited. Samples of bone, tissue and blood were collected, and RNA sequencing was performed in 24 patients with aseptic loosening and 26 controls. Differentially expressed miRNA in plasma was matched to differentially expressed mRNA in periprosthetic bone and tissue. Western blot was used to validate protein expression.

RESULTS

Seven miRNA was differentially expressed in the plasma of patients with osteolysis (logFC >|2|, adj-P < 0.05). Three thousand six hundred and eighty mRNA genes in bone and 427 mRNA genes in tissue samples of osteolysis patients were differentially expressed (logFC >|2|, adj-P < 0.05). Gene enrichment analysis and pathway analysis revealed two miRNA (miR-1246 and miR-6089) had multiple gene targets in the Wnt signalling pathway in the local bone and tissues which regulate bone metabolism.

CONCLUSION

These results suggest that aseptic loosening may be regulated by miR-1246 and miR-6089 via the Wnt signalling pathway.

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.

Denosumab for treating periprosthetic osteolysis; study protocol for a randomized, double-blind, placebo-controlled trial

Background

Wear-induced osteolysis is the main factor in reducing the longevity of total hip arthroplasty (THA). The transmembrane Receptor Activator of Nuclear Factor κ B (RANK) and its corresponding ligand RANKL is an important regulator of osteoclast activity and bone resorption and is associated with osteolysis around implant. Inhibiting RANKL with denosumab is effective in vivo in preventing osteoporosis-related fractures. In vitro, osteoclasts can be blocked in animal models of osteolysis. We hypothesize that denosumab is effective in reducing wear-induced osteolysis around uncemented acetabular implants in THA.

Methods/design

A randomized, double-blind, placebo-controlled trial will be conducted. We will include 110 patients, 40–85 years of age, with a known osteolytic lesion around an uncemented acetabular component ≥7 years after the primary operation. The patients will be randomized in a 1:1 ratio to subcutaneous injections of 60 mg denosumab or placebo for a total of 6 doses with start on day one and every 6 months with last treatment at 30 months. The primary endpoint will be the change in volume of the osteolytic lesion at 3 years measured with three-dimensional computed tomography (3D-CT). Secondary endpoints include functional outcome scores, change in bone mineral density of the lumbar spine, serological markers of bone turnover and adverse events.

Discussion

In vitro results of both bisphosphonates and RANKL inhibitors have been promising, showing reduced osteolysis with treatment. This is, to our knowledge, the first clinical trial testing the efficacy of denosumab in reducing wear-induced osteolysis. The study is an academic, phase II trial from an independent center and is designed to demonstrate efficacy in reducing volume of osteolytic lesions around a total hip arthroplasty.

Trial registration

ClinicalTrials.gov (NCT02299817) 2014-11-20

Are biologic treatments a potential approach to wear- and corrosion-related problems?

WHERE ARE WE NOW?: Biological treatments, defined as any nonsurgical intervention whose primary mechanism of action is reducing the host response to wear and/or corrosion products, have long been postulated as solutions for osteolysis and aseptic loosening of total joint arthroplasties. Despite extensive research on drugs that target the inflammatory, osteoclastic, and osteogenic responses to wear debris, no biological treatment has emerged as an approved therapy. We review the extensive preclinical research and modest clinical research to date, which has led to the central conclusion that the osteoclast is the primary target. We also allude to the significant changes in health care, unabated safety concerns about chronic immunosuppressive/antiinflammatory therapies, industry's complete lack of interest in developing an intervention for this condition, and the practical issues that have narrowly focused the possibilities for a biologic treatment for wear debris-induced osteolysis. WHERE DO WE NEED TO GO?: Based on the conclusions from research, and the economic, regulatory, and practical issues that limit the future directions toward the development of a biologic treatment, there are a few rational approaches that warrant investigation. These largely focus on FDA-approved osteoporosis therapies that target the osteoclast (bisphosphonates and anti-RANK ligand) and recombinant parathyroid hormone (teriparatide) prophylactic treatment to increase osseous integration of the prosthesis to overcome high-risk susceptibility to aseptic loosening. The other roadblock that must be overcome if there is to be an approved biologic therapy to prevent the progression of periprosthetic osteolysis and aseptic loosening is the development of radiological measures that can quantify a significant drug effect in a randomized, placebo-controlled clinical trial. We review the progress of volumetric quantification of osteolysis in animal studies and clinical pilots. HOW DO WE GET THERE?: Accepting the aforementioned rigid boundaries, we describe the emergence of repurposing FDA-approved drugs for new indications and public (National Institutes of Health, FDA, Centers for Disease Control and Prevention) and private (universities and drug and device manufactures) partnerships as the future roadmap for clinical translation. In the case of biologic treatments for wear debris-induced osteolysis, this will involve combined federal and industry funding of multicenter clinical trials that will be run by thought leaders at large medical centers.

Altered load transfer in the pelvis in the presence of periprosthetic osteolysis

Periprosthetic osteolysis in the retroacetabular region with cancellous bone loss is a recognized phenomenon in the long-term follow-up of total hip replacement. The effects on load transfer in the presence of defects are less well known. A validated, patient-specific, 3D finite element (FE) model of the pelvis was used to assess changes in load transfer associated with periprosthetic osteolysis adjacent to a cementless total hip arthroplasty (THA) component. The presence of a cancellous defect significantly increased (p &lt; 0.05) von Mises stress in the cortical bone of the pelvis during walking and a fall onto the side. At loads consistent with single leg stance, this was still less than the predicted yield stress for cortical bone. During higher loads associated with a fall onto the side, highest stress concentrations occurred in the superior and inferior pubic rami and in the anterior column of the acetabulum with larger cancellous defects.

Early diagnosis of orthopedic implant failure using macromolecular imaging agents

PURPOSE

To develop and evaluate diagnostic tools for early detection of wear particle-induced orthopaedic implant loosening.

METHODS

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer was tagged with a near infrared dye and used to detect the inflammation induced by polymethylmethacrylate (PMMA) particles in a murine peri-implant osteolysis model. It was established by inserting an implant into the distal femur and challenging with routine PMMA particles infusion. The osteolysis was evaluated by micro-CT and histological analysis at different time points.

RESULTS

Significant peri-implant osteolysis was found 3-month post PMMA particle challenge by micro-CT and histological analysis. At 1-month post challenge, when there was no significant peri-implant bone loss, the HPMA copolymer-near infrared dye conjugate was found to specifically target the femur with PMMA particles deposition, but not the contralateral control femur with phosphate buffered saline (PBS) infusion.

CONCLUSION

The results from this study demonstrate the feasibility of utilizing the macromolecular diagnostic agent to detect particle-induced peri-implant inflammation prior to the development of detectable osteolysis. Recognition of this early pathological event would provide the window of opportunity for prevention of peri-implant osteolysis and subsequent orthopaedic implant failure.

Chronic inflammation in biomaterial-induced periprosthetic osteolysis: NF-κB as a therapeutic target

Biomaterial-induced tissue responses in patients with total joint replacement are associated with the generation of wear particles, which may lead to chronic inflammation and local bone destruction (periprosthetic osteolysis). Inflammatory reactions associated with wear particles are mediated by several important signaling pathways, the most important of which involves the transcription factor NF-κB. NF-κB activation is essential for macrophage recruitment and maturation, as well as the production of pro-inflammatory cytokines and chemokines such as TNF-α, IL-1β, IL-6 and MCP1. In addition, NF-κB activation contributes to osteoclast differentiation and maturation via RANK/RANKL signaling, which increases bone destruction and reduces bone formation. Targeting individual downstream cytokines directly (such as TNF-α or IL-1β) may not effectively prevent wear particle induced osteolysis. A more logical upstream therapeutic approach may be provided by direct modulation of the core IκB/IKKα/β/NF-κB signaling pathway in the local environment. However, the timing, dose and strategy for administration should be considered. Suppression of chronic inflammation via inhibition of NF-κB activity in patients with malfunctioning joint replacements may be an effective strategy to mitigate wear particle induced periprosthetic osteolysis.

Review of periprosthetic osteolysis in total joint arthroplasty: an emphasis on host factors and future directions

Periprosthetic osteolysis is one of the leading causes of total joint revision procedures. If allowed to progress in the absence of radiographic diagnosis and/or proper medical treatment, osteolysis may result in aseptic loosening yielding failure of the implant and the need for complex revision arthroplasty. The purpose of this review was to assess the current understanding of periprosthetic osteolysis with an emphasis on host factors and future directions. A PubMed search was conducted using the following key words; osteolysis, periprosthetic osteolysis, osteolysis imaging. Pertinent articles, as it pertained to the outline of the review, were selected. Periprosthetic osteolysis stems from numerous risk factors. Osteolysis host characteristic risk factors include gender, body weight, and genetics. Current implant designs have reduced the incidence of this disease; however no current design has been able to replicate the in vivo characteristics and therefore development of wear particles continues to be seen. Advanced methods of imaging diagnosis are on the rise, however early imaging diagnosis is currently ineffective. Pharmacologic intervention appears to be a logical avenue for medical intervention, but no approved drug therapy to prevent or inhibit periprosthetic osteolysis is currently available. Although the rate of periprosthetic osteolysis seems to be decreasing with advances in implant design and increased knowledge of the biological process of wear particle induced osteolysis, the rapid increase in the total number of total joint arthroplasties over the next two decades means that better ways of detecting and treating periprosthetic osteolysis are greatly needed.

The aqueous extract of Angelica sinensis, a popular Chinese herb, inhibits wear debris-induced inflammatory osteolysis in mice

BACKGROUND

More and more studies have shown Angelica sinensis' (AS) therapeutic action on chronic inflammatory diseases in recent years. We investigated effects of aqueous extract of AS on inflammatory cytokines release and wear debris particles-induced osteolysis.

MATERIALS AND METHODS

Ultra high molecular weight polyethylene (UHMWPE) particles were used to induce inflammation in RAW264.7 cell and C57BL/J6 mice. AS extract was obtained through a series of purification steps, and divided into high dose group and low dose group during the research of cell culture, tissue culture, and animal treatment. After 72 h culture with optimal particles, supernatants were collected for cytokine analysis. Calvaria were harvested from the mice model after 10 d treatment with the AS extract. Six calvaria of each group were cultured into medium for 72 h for analyzing cytokine generated in vivo. Histologic analyses and micro-computed tomography (micro-CT) scan were used to determine osteoclastogenesis and inflammatory bone resorption.

RESULTS

Concentration of tumor necrosis-alpha (TNF-α) and interleukin-1beta (IL-1β) was significantly attenuated by AS extract both in vitro and in vivo. The osteolysis area and the osteoclast numbers were decreased from 0.406 ± 0.0799 to 0.117 ± 0.0103 mm(2), and from 22.7 ± 5.0 to 11.3 ± 1.8, respectively (P < 0.01). Compared with the control group, the protection effects of AS extract was further confirmed with data of the more accurate 3-dimension micro-CT reconstruction.

CONCLUSIONS

This study suggests a potential resolution of inhibiting wear debris particles-induced inflammatory bone resorption, as well as a possible way of inhibiting aseptic loosening after joint replacement surgery.

Osteolysis propensity among bilateral total hip arthroplasty patients

Because some patients with high wear rates demonstrate extensive osteolysis whereas other patients with similarly high wear rates show little or no evidence of osteolysis, we hypothesized that both polyethylene wear and a patient-specific propensity mediate the development of osteolysis. We evaluated wear and osteolysis using computed tomography and radiographs among 46 patients who had undergone bilateral total hip arthroplasties (THAs). A radiographic patient-specific propensity for osteolysis associated with each THA was quantified by dividing the amount of osteolysis by the volumetric wear. Using a multivariate regression analysis to simultaneously consider the influence of polyethylene wear and patient propensity, we found that both factors are associated with the amount of osteolysis around a THA and that they appear to be of similar importance.

Surveillance of systemic trafficking of macrophages induced by UHMWPE particles in nude mice by noninvasive imaging

Macrophages constitute a major part of the cell response to wear particles produced at articulating and nonarticulating interfaces of joint replacements. This foreign body reaction can result in periprosthetic osteolysis and implant loosening. We demonstrate that ultra-high molecular weight polyethylene (UHMWPE) particles induce systemic trafficking of macrophages by noninvasive in vivo imaging and immunohistochemistry. The distal femora of nude mice were injected with 60 mg/mL UHMWPE suspension or saline alone. Reporter RAW264.7 macrophages that stably expressed the bioluminescent reporter gene and the fluorescence reporter gene were injected intravenously. Bioluminescence imaging was performed using an in vivo imaging system immediately after macrophage injection and at 2-day intervals. Compared with the nonoperated contralateral femora, at day 4, 6, and 8, the bioluminescent signal of femora containing UHMWPE suspension increased 1.30 +/- 0.09-, 2.36 +/- 0.92-, and 10.32 +/- 7.61-fold, respectively. The values at same time points for saline-injected control group were 1.08 +/- 0.07-, 1.14 +/- 0.27-, and 1.14 +/- 0.35-fold, respectively. The relative bioluminescence of the UHMWPE group was higher at all postinjection days and significantly greater than the saline group at day 8 (p < 0.05). Histological analysis confirmed the presence of reporter macrophages within the medullary canal of mice with implanted UHMWPE particles. The presence of UHMWPE particles induced enhanced bone remodeling activity. Clinically relevant UHMWPE particles stimulated the systemic recruitment of macrophages during an early time course using the murine femoral implant model. Interference with systemic macrophage trafficking may potentially mitigate UHMWPE particle-induced periprosthetic osteolysis.

Medium term follow-up of the AES ankle prosthesis: High rate of asymptomatic osteolysis

BACKGROUND

The AES (Ankle Evolutive System) is a cobalt-chromium three-component ankle prosthesis with a hydroxyapatite coating, similar to the Buechel-Pappas ankle prosthesis, but with some modifications. Our objective was to assess its medium term follow-up results as well as its complications.

METHODS

21 patients (mean age of 57.6 years) were operated by a total ankle arthroplasty (TAA), using the AES implant, according to the standard technique. Only 18 patients were included. The other three patients were excluded from the study: two had been revised for avascular talar necrosis and one patient was happy with her outcome but could not present for logistic reasons at the last follow-up. Indications for surgery included posttraumatic osteoarthritis, primary osteoarthritis, hemochromatosis, rheumatic arthritis and osteoarthritis as a sequel of ankle instability. All patients were analyzed clinically and radiologically. Special attention was given to the presence or not of areas of osteolysis around the implants as well on conventional radiography as on CT-scan imaging, according to a specific protocol.

RESULTS

The mean follow-up was 39.4 months. Average American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score improved from 52.2 preoperatively to 86.6 postoperatively. No intra-operative complications or early complications have been noted. Delayed complications were the following: one valgus malalignment, one recurrent painful anterior heterotrophic bone formation. Above all, we noted on conventional X-ray the presence of osteolysis in 77% (14) of our patients, with a size of 0.5-1cm or greater on conventional X-ray. The most vulnerable area seemed to be the posterior tibial plafond. The four remaining patients did not show any cyst formation on X-ray but did also, just as the other 14 patients, on the CT-scan. CT-scan, on the contrary, found more osteolysis in the body of the talus, underneath the implant, an area masked on conventional X-ray. Only one patient was revised with allograft bone filling of a symptomatic osteolysis, without the need for implant removal.

CONCLUSIONS

This retrospective study shows a high frequency of delayed appearance of osteolysis (77%) in 18 AES total ankle arthroplasties. Fortunately at this moment and considering one revision, this considerable amount of asymptomatic osteolysis could not warrant a durable uncomplicated outcome.

Upregulation of MMP-13 via Runx2 in the stromal cell of Giant Cell Tumor of bone

Giant Cell Tumor of bone (GCT) is an aggressively osteolytic and cytokine-rich bone tumor. Previous work in our lab has shown that matrix metalloproteinase-13 (MMP-13) is the principal proteinase expressed by the mesenchymal stromal cells of GCT. The Runx2 transcription factor is known to have a binding site in the MMP-13 promoter region, and we have previously found this transcription factor to be constitutively expressed in GCT stromal cells. The purpose of this study was to determine the role of Runx2 in MMP-13 regulation in GCT stromal cells. Following in vitro stimulation of GCT stromal cells with incremental concentrations of cytokine IL-1beta or TNF-alpha, the level of MMP-13 mRNA expression increased dramatically over 100-fold with a concomitant increase in MMP-13 protein expression. Inhibition of the ERK and JNK signaling pathways inhibited the upregulation of MMP-13 in these cells. Runx2 siRNA knockdown resulted in MMP-13 knockdown, and this effect was amplified following cytokine stimulation. Our study provides the first evidence that Runx2 may play a crucial role in cytokine-mediated MMP-13 expression in GCT stromal cells.

The effect of Lipoxin A4 on the interaction between macrophage and osteoblast: possible role in the treatment of aseptic loosening

Background

Aseptic loosening (AL) is the main problem of total joints replacement (TJR) by the implantation of permanently prosthetic components. In vitro and in vivo studies have clearly demonstrated that wear debris and its byproducts could trigger inflammation in the peri-implant tissue. Lipoxins (LXs) are endogenous eicosanoids synthesized locally from arachidonate acid (AA) at sites of inflammation and mediate pro-resolving activity. A number of studies have demonstrated the effect of LXA₄ to counteract inflammation in different cell and animal models, but till now, no relative report about the role of LXs in progress or prevention of AL.

Methods

Murine RAW264.7 macrophage cell line and MC3T3-E1 osteoblasts (OB) cell line were purchased. Co-cultured model of these two cell lines was established. To explore the effect of exogenous Lipoxin A₄ (LXA₄) on polymethylmethacrylate (PMMA) induced inflammation, pro-inflammatory cytokines including TNF-α, IL-1β, PGE₂ and GM-CSF were measured by ELISA kits and bone resorption was quantified by measuring calcium release from 5-day-old mice calvaria in vitro. To determine further the endogenous effect of LXA₄, cells were co-cultured and with or without 15-lipoxygease (15-LO) blocking by 15-LO siRNA. Both real-time PCR and western blotting were applied to confirm the inhibitory efficiency of 15-LO by siRNA.

Results

0.1 mg/ml, 0.5 mg/ml and 1.0 mg/ml PMMA showed a time-dependent manner to trigger production of all the pro-inflammatory cytokines studied. Exogenous 0–100 nM LXA₄ presented an inhibitory effect on both generation of above cytokines and PMMA stimulated calvarial bone resorption with a dose-dependent manner. LXA₄ in supernatant from neither rest macrophages nor macrophages cultured alone exposing to PMMA was detectable. In co-cultured cells challenged by PMMA, LXA₄ was increased significantly, while, this enhance could be partly inhibited by 15-LO siRNA. When LXA₄ generation was blocked with 15-LO siRNA, the PMMA induced pro-inflammatory cytokines were elevated and bone resorption was accelerated.

Conclusion

In the present study, we demonstrated that LXA₄ had a favorable inhibitory effect on PMMA-induced inflammation in a macrophage and OB co-culture system.

Effects of NF-kappaB inhibitor on titanium particulate-induced inflammation in a murine model

BACKGROUND

Activation of nuclear factor kappa B (NF-kappaB) signaling in response to implant particulates may be critical in the pathogenesis of implant loosening after joint arthroplasty. The purpose of this study was to investigate the inhibitory effects of pyrrolidine dithiocarbamate (PDTC) in a murine model of inflammation induced by titanium (Ti) particulates.

MATERIALS AND METHODS

Ti particulates were introduced into established air pouches on C57BL/6J mice. Mice were injected intraperitoneally with either high-dose PDTC (100 mg/kg) or low-dose PDTC (50 mg/kg). Mice without drug treatment, as well as mice injected with saline alone were included. Each group consisted of sixteen mice. The membranes and lavage fluid were harvested 2 d or 7 d after injection of particulate suspension for histological and molecular analysis.

RESULTS

Histologic analysis showed that PDTC reduced inflammatory responses in air pouches, that is, thinner membrane and decreased cellular infiltration. In addition, PDTC reduced the release of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in the lavage fluid or supernatant of homogenates as evaluated by ELISA.

CONCLUSION

These results suggest that PDTC inhibits Ti particulate-induced inflammatory responses in the murine model; thus it represents a promising therapeutic candidate for the prevention and treatment of implant loosening.

Systemic trafficking of macrophages induced by bone cement particles in nude mice

Macrophages play an important role in the biological response to wear particles, which can result in periprosthetic osteolysis and implant loosening. In this study, we demonstrate that polymer particles induce systemic trafficking of macrophages by non-invasive in vivo imaging and immunohistochemistry. The distal femora of nude mice were injected with 10% (w/v) Simplex bone cement (BC) suspensions or saline (PBS). Reporter RAW264.7 macrophages which stably expressed the bioluminescent reporter gene fluc, and the fluorescence reporter gene gfp, were injected intravenously. Bioluminescence imaging was performed immediately and periodically at 2-day intervals until day 14. Compared to the non-operated contralateral femora, the bioluminescent signal of femora injected with BC suspension increased 4.7+/-1.6 and 7.8+/-2.9-fold at day 6 and 8, respectively. The same values for PBS group were 1.2+/-0.2 and 1.4+/-0.5, respectively. The increase of bioluminescence of the BC group was significantly greater than the PBS group at day 8 (p<0.05) and day 6 (p<0.1). Histological study confirmed the presence of reporter macrophages within the medullary canal of mice that received cement particles. Modulation of the signaling mechanisms that regulate systemic macrophage trafficking may provide a new strategy for mitigating the chronic inflammatory response and osteolysis associated with wear debris.

What are the guidelines for the surgical and nonsurgical treatment of periprosthetic osteolysis?

Periprosthetic osteolysis is most often diagnosed by plain radiographs. Because these radiographs routinely underestimate the extent of the lesion, three-dimensional imaging should be used early in the evaluation process to confirm the presenting extent of disease. If the osteolytic process is asymptomatic, scheduled regular follow-up should be instituted until the lesion can be confirmed to be stable or until the decision is made to proceed with surgery. Nonsurgical management with pharmacologic agents has not proved to be effective. If surgery is contemplated, a three-dimensional evaluation with magnetic resonance imaging or helical computed tomography can assist in preoperative planning. Surgical intervention requires complete débridement of the lesional membrane and removal of the wear-generator--with or without component removal and with or without bone grafting, depending on the individual circumstances. A standardized follow-up evaluation mechanism for all patients should be a part of total joint arthroplasty management.

Inhibiting wear particles-induced osteolysis with doxycycline

AIM

To study the effect of doxycycline (DOX) on osteoclastogenesis, mature osteoclast fate and function, wear particles-induced osteoeolysis, and to provide some foundation for treating aseptic loosening and osteolysis after joint arthroplasty.

METHODS

Osteoclasts were generated from mouse bone marrow monocytes with the receptor activator of NF-kappaB ligand and the macrophage colony stimulating factor. DOX at a concentration of 5, 10, 15, and 20 microg/mL was respectively added to the medium. Seven days later, the osteoclasts were determined through tartrate-resistant acid phosphatase (TRAP) staining. Mature osteoclasts were isolated from newborn rabbits and cultured for 3 d in 24-well plates or on bone slices. DOX at a concentration of 5, 10, 15, and 20 microg/mL was respectively added to the medium. After TRAP staining, the osteoclasts were counted, resorption on bone slices was quantified, and the area was calculated after toluidine blue and Mayer-hematoxylin staining. Polymethyl methacrylate (PMMA) or ultra-high molecular weight polyethylene (UHMWPE) particles were implanted on the calvariae of C57BL/J6 mice. DOX, at a dose of 2 and 10 mg x kg(-1) x d(-1), was respectively given intraperitoneally for 7 d. Seven days later, the calvariae were removed and processed for pathological analysis.

RESULTS

DOX treatment effectively inhibited in vitro osteoclastogenesis, affected the fate of mature osteoclasts, and inhibited mature osteoclasts, causing bone resorption. In vivo data indicated that DOX strongly inhibited PMMA or UHMWPE-induced osteolysis and osteoclastogenesis.

CONCLUSION

DOX can effectively inhibit osteoclastogenesis and affect mature osteoclast fate and suppress wear particles induced by osteolysis and osteoclastogenesis. DOX might be useful in the treatment or prevention of wear particles-induced osteolysis and aseptic loosening for its effect on osteoclast generation and mature osteoclast fate and function.