Inhibition of particulate debris-induced osteolysis by alendronate in a rat model

Osseointegration Pharmacology: A Systematic Mapping Using Artificial Intelligence

Clinical performance of osseointegrated implants could be compromised by the medications taken by patients. The effect of a specific medication on osseointegration can be easily investigated using traditional systematic reviews. However, assessment of all known medications requires the use of evidence mapping methods. These methods allow assessment of complex questions, but they are very resource intensive when done manually. The objective of this study was to develop a machine learning algorithm to automatically map the literature assessing the effect of medications on osseointegration. Datasets of articles classified manually were used to train a machine-learning algorithm based on Support Vector Machines. The algorithm was then validated and used to screen 599,604 articles identified with an extremely sensitive search strategy. The algorithm included 281 relevant articles that described the effect of 31 different drugs on osseointegration. This approach achieved an accuracy of 95%, and compared to manual screening, it reduced the workload by 93%. The systematic mapping revealed that the treatment outcomes of osseointegrated medical devices could be influenced by drugs affecting homeostasis, inflammation, cell proliferation and bone remodeling. The effect of all known medications on the performance of osseointegrated medical devices can be assessed using evidence mappings executed with highly accurate machine learning algorithms.

Arthrotomy-based preclinical models of particle-induced osteolysis: A systematic review

We completed a systematic literature review of in vivo animal models that use arthrotomy-based methods to study particle-induced peri-implant osteolysis. The purpose of the review was to characterize the models developed to date, to determine the questions addressed, to assess scientific rigor and transparency, and to identify gaps in knowledge. We probed three literature databases (Medline, Embase, and Scopus) and found 77 manuscripts that fit the search parameters. In the most recent 10 years, researchers mainly used rat and mouse models, whereas in the previous 20 years, large animal, canine, and rabbit models were more common. The studies have demonstrated several pathophysiology pathways, including macrophage migration, particle phagocytosis, increased local production of cytokines and lysosomal enzymes, elevated bone resorption, and suppressed bone formation. The effect of variation in particle characteristics and concentration received limited attention with somewhat mixed findings. Particle contamination by endotoxin was shown to exacerbate peri-implant osteolysis. The possibility of early diagnosis was demonstrated through imaging and biomarker approaches. Several studies showed that both local and systemic delivery of bisphosphonates inhibits the development of particle-induced osteolysis. Other methods of inhibiting osteolysis include the use of anabolic agents and altering the implant design. Few studies examined non-surgical rescue of loosened implants, with conflicting results with alendronate. We found that the manuscripts often lacked the methodological detail now advocated by the ARRIVE guidelines, suggesting that improvement in reporting would be useful to maximize rigor and transparency. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2595-2605, 2017.

Role of a nitrogenous bisphosphonate (local delivery) incorporated vitreous coating (with/without polymer) on surgical grade SS316L implant material to improve fixation at the damaged tissue site

This study demonstrates the material and biological properties of a unique osteogenic drug eluting (local) coating on load bearing SS316L implant material with a tunable release profile.

Effect of alendronate on pseudomembrane cytokine expression in patients with aseptic osteolysis

To determine whether alendronate alters the pseudomembrane inflammatory cytokine profile in patients with established aseptic osteolysis. A prospective, double-blind, randomized, controlled trial was conducted. Ten individuals listed for revision surgery for aseptic failure of a primary cemented arthroplasty were randomly assigned placebo/alendronate 70 mg once weekly for 8 weeks before revision surgery. Formalin-preserved pseudomembrane samples were paraffin-sectioned for immunohistochemical analysis to assess inflammatory cytokine protein expression. Polymerase chain reaction was carried out to assess expression of relevant mRNA. No significant difference was detected in the inflammatory cytokine protein or mRNA expression between groups. Alendronate 70 mg administered for an 8-week period before surgery did not alter the pseudomembrane inflammatory cytokine profile in patients with established aseptic osteolysis. Any potential biological effects may occur due to downstream effects on osteoclast and osteoblast function.

Efficacy of a p38 mitogen activated protein kinase inhibitor in mitigating an established inflammatory reaction to polyethylene particles in vivo

The inhibitor of p38 mitogen-activated protein kinase (MAPK) is of interest in the nonoperative treatment of periprosthetic osteolysis due to wear particles. Previous studies demonstrated that an oral p38 MAPK inhibitor did not suppress bone formation when given during the initial phase of tissue differentiation. However, the oral p38 MAPK inhibitor also did not curtail the foreign body and chronic inflammatory response to particles when given simultaneously. The purpose of the current study was to examine the efficacy of a p38 MAPK inhibitor, SCIO-323, on mitigating an established inflammatory reaction that parallels the clinical situation more closely. The Bone Harvest Chamber was implanted in rabbits and submicron polyethylene particles were placed in the chamber for 6 weeks. The contents of the chambers were harvested every 6 weeks. Oral treatment with the SCIO-323 included delivery for 3 weeks and stopping for 3 weeks, delivery for 3 weeks after an initial 3-week delay, and delivery for 6 weeks continuously. Administration of the SCIO-323 continuously for 6 weeks with/without the presence of particles, or for the initial 3 of 6 weeks had minor effects on bone ingrowth. After establishing a particle-induced chronic inflammatory reaction for 3 weeks, administration of SCIO-323 for a subsequent 3 weeks suppressed net bone formation. The activity of osteoclast-like cells remained low among all treatments when compared with the first control. Using the present model, the oral p38 MAPK inhibitor was ineffective in improving bone ingrowth in the presence of polyethylene particles.

Does bone quality predict loosening of cemented total hip replacements?

We matched 78 patients with a loose cemented Charnley Elite Plus total hip replacement (THR) by age, gender, race, prosthesis and time from surgery with 49 patients with a well-fixed stable hip replacement, to determine if poor bone quality predisposes to loosening. Clinical, radiological, biomechanical and bone mineral density indicators of bone quality were assessed.

Patients with loose replacements had more pain, were more likely to have presented with atrophic arthritis and to have a history of fragility fracture, narrower femoral cortices and lower peri-prosthetic or lumbar spine bone mineral density (all t-test, p < 0.01). They also tended to be smokers (chi-squared test, p = 0.08). Vitamin-D deficiency was common, but not significantly different between the two groups (t-test, p = 0.31)

In this series of cemented hip replacements performed between 1994 and 1998, aseptic loosening was associated with poor bone quality. Patients with a THR should be screened for osteoporosis and have regular radiological surveillance.

Effects of a p38 MAP kinase inhibitor on bone ingrowth and tissue differentiation in rabbit chambers

The effects of an oral p38 mitogen-activated protein kinase (MAPK) inhibitor and polyethylene particles separately and together on tissue differentiation in the bone harvest chamber (BHC) in rabbits over a 3-week treatment period were investigated. The harvested tissue was analyzed histomorphometrically for markers of bone formation (percentage of bone area), osteoblasts (alkaline phosphatase staining), and osteoclasts (CD51, the alpha chain of the vitronectin receptor). Polyethylene particles decreased the percentage of bone ingrowth and staining for alkaline phosphatase. The p38 MAPK inhibitor alone decreased alkaline phosphatase staining. When the oral p38 MAPK inhibitor was given and the chamber contained polyethylene particles, there was a suppression of bone ingrowth and alkaline phosphatase staining. In contrast to oral non-steroidal anti-inflammatory drugs (NSAIDs) and local Interleukin-1 receptor antagonist (IL-1ra) administration, the oral p38 MAPK inhibitor alone did not suppress bone formation when given during the initial phase of tissue differentiation. Particle-induced inflammation and the foreign body reaction were not curtailed when the p38 MAPK inhibitor was given simultaneously with particles. Additional experiments are needed to establish the efficacy of p38 MAPK inhibitor administration on mitigating an established inflammatory and foreign body reaction that parallels the clinical situation more closely.

The biology of aseptic osteolysis

Total hip arthroplasty is one of the most commonly performed and successful elective orthopaedic procedures. However, numerous failure mechanisms limit the long-term success including aseptic osteolysis, aseptic loosening, infection, and implant instability. Aseptic osteolysis and subsequent implant failure occur because of a chronic inflammatory response to implant-derived wear particles. To reduce particulate debris and their consequences, implants have had numerous design modifications including high-molecular-weight polyethylene sockets and noncemented implants that rely on bone ingrowth for fixation. Surgical techniques have improved cementation with the use of medullary plugs, cement guns, lavage of the canal, pressurization, centralization of the stem, and reduction in cement porosity. Despite these advances, aseptic osteolysis continues to limit implant longevity. Numerous proinflammatory cytokines, such as interleukin-1, interleukin-6, tumor necrosis factor-alpha, and prostaglandin E2, have proosteoclastogenic effects in response to implant-derived wear particles. However, none of these cytokines represents a final common pathway for the process of particle-induced osteoclast differentiation and maturation. Recent work has identified the fundamental role of the RANKL-RANK-NF-kappaB pathway not only in osteoclastogenesis but also in the development and function the immune system. Thus, the immune system and skeletal homeostasis may be linked in the process of osteoclastogenesis and osteolysis.

Parathyroid hormone and leptin--new peptides, expanding clinical prospects

There are three injectable and one oral bone-building (i.e., bone anabolic) parathyroid hormone (PTH) peptides. One of the four, Lilly's injectable teriparatide (Forteo), is currently being used, and the other three are in clinical trials. They are being used or assessed only for treating postmenopausal osteoporosis. However, their potential clinical targets now extend far beyond osteoporosis. They can accelerate the mending of even severe non-union fractures; they will probably be used to strengthen the anchorage of pros-theses to bone; they have been shown to treat psoriasis that has resisted other treatments; they can increase the size of haematopoietic stem cell proliferation and accelerate the endogenous repopulation or repopulation by donor transplants of bone marrow depleted by chemotherapeutic drugs; and they may prevent vascular ossification. Leptin, a member of the cytokine superfamily has a PTH-like osteogenic activity and may even partly mediate PTH action. But leptin has two drawbacks that cloud its therapeutic future. First, apart from directly stimulating osteoblastic cells, it targets cells in the hypothalamic ventromedial nuclei and through them it reduces oestrogenic activity by promoting osteoblast-suppressing adrenergic activity. Second, it stimulates vascular and heart valve ossification, which leads to such events as heart failure and diabetic limb amputations.

Use of bisphosphonates to improve the durability of total joint replacements

Total joint arthroplasty is very effective for improving the quality of life of patients with end-stage arthritis. Despite advances in materials, surgical technique, and rehabilitation regimens, joint replacements are still fraught with complications leading to their premature failure. Aseptic loosening and osteolysis are the primary causes of implant failure. Other reasons include early migration of components leading to instability, lack of ingrowth into implant porosities, and bone loss caused by stress shielding. Pharmaceutical agents used for preventing and managing postmenopausal osteoporosis (eg, bisphosphonates) may in the future play an important role in improving the long-term duration of joint arthroplasties. Early findings indicate that bisphosphonates upregulate bone morphogenetic protein-2 production and stimulate new bone formation. Because of their anabolic effect on osteoblasts, bisphosphonates have the potential to enhance bone ingrowth into implant porosities, prevent bone resorption under adverse conditions, and dramatically extend the long-term durability of joint arthroplasties. The long-term effects of bisphosphonate use on the mechanical properties of bone have not been adequately investigated. Along with improvements in implant design and material properties, bisphosphonates and other pharmaceutical agents may, in the near future, be part of the growing armamentarium that provides more durable joint arthroplasties.

Predictions on preserving bone mass in knee arthroplasty with bisphosphonates

Using a computational model of bone adaptation, we investigated the long-term ability of bisphosphonates to minimize proximal bone loss that is associated with stress shielding in the tibia after long-stemmed total knee arthroplasty (TKA). When invoking bisphosphonate effects, the remodeling activity was suppressed, and the resorption size was reduced. Compared with the untreated simulation, bisphosphonate slowed the rate of bone loss after TKA (42% reduction in bone loss at 1 year). Activating the drug 3 months before the surgery reversed bone loss associated with the reduction in such activities as walking, but it did not provide any substantial benefit in the long-term. Late bisphosphonate treatment did not reverse the bone loss that occurred 3.5 years after TKA, although it preserved 3% of bone normally lost without treatment.

Polyethylene and titanium particles induce osteolysis by similar, lymphocyte-independent, mechanisms

Periprosthetic osteolysis is a major clinical problem that limits the long-term survival of total joint arthroplasties. Osteolysis is induced by implant-derived wear particles, primarily from the polyethylene bearing surfaces. This study examined two hypotheses. First, that similar mechanisms are responsible for osteolysis induced by polyethylene and titanium particles. Second, that lymphocytes do not play a major role in particle-induced osteolysis. To test these hypotheses, we used the murine calvarial model that we have previously used to examine titanium-induced osteolysis. Polyethylene particles rapidly induced osteolysis in the murine calvaria 5-7 days after implantation. The polyethylene-induced osteolysis was associated with large numbers of osteoclasts as well as the formation of a thick periosteal fibrous tissue layer with numerous macrophages containing phagocytosed polyethylene particles. Polyethylene-induced osteolysis was rapidly repaired and was undetectable by day 21 after implantation. Lymphocytes were noted in the fibrous layer of wild-type mice. However, the amount of osteolysis and cytokine production induced by polyethylene particles was not substantially affected by the lack of lymphocytes in Pfp/Rag2 double knock out mice. All of these findings are similar to our observations of osteolysis induced by titanium particles. These results provide strong support for both of our hypotheses: that similar mechanisms are responsible for osteolysis induced by polyethylene and titanium particles and that lymphocytes do not play a major role in particle-induced osteolysis.

Pharmacologic modulation of periprosthetic osteolysis

Wear and periprosthetic osteolysis of total joint replacements continue to be the most important problems in arthroplasty surgery. Despite the introduction of improved technologies including alternative bearing surfaces for TJRs, wear is inevitable because of relative movement at different interfaces and processes such as electrolysis and material degradation. Worn, clinically failing implants need to be followed closely and revised when appropriate. However, early wear and minor osteolysis do not result necessarily in progressive failure of the prosthesis. Indeed such cases may be followed up clinically and radiographically to establish the functional and biologic sequelae of wear and the timeline of these events. This scenario provides an opportunity to modulate the adverse biologic reaction associated with wear particles that includes chronic inflammation, the foreign body response, and periprosthetic bone destruction. Currently, immunological events associated with wear particles are becoming understood more clearly. Strategies to mitigate adverse processes associated with wear debris include local or systemic administration of immune modulators, signaling molecules, anti-inflammatory agents and growth factors, and altering osteoclast function. Ultimately, prevention of accelerated wear and periprosthetic osteolysis will be achieved with improved bearing surfaces and prosthetic designs.

Regulation of osteoclast activity in peri-implant tissues

Implants, particularly joint replacement prostheses, are one of the great success stories of modern medicine. However, too many implants fail prematurely, mainly due to aseptic bone loss around the implant. This paper reviews our current understanding of the role of osteoclasts in this peri-implant bone lysis. Prosthetic particles, often produced by articulating prostheses, are one of the major causes of elevated osteoclast lysis of peri-implant bone. Over the past decade there have been major advances in our understanding of the factors that regulate osteoclast activity, many of which were found to be important in osteoclast formation and activity in the peri-implant tissues. These factors are targets of a number of recently developed drugs that have been used successfully to prevent and treat peri-implant bone lysis in experimental models. Treatments such as these are being used in a number of bone loss pathologies in humans and have the potential for successful treatment of peri-implant osteolysis. In addition, understanding how different biomaterials influence the expression of key osteoclastogenic factors may allow us to select biomaterials for implantation that will last the lifetime of the recipient.

Regulation of osteoclast activity in peri-implant tissues

Implants, particularly joint replacement prostheses, are one of the great success stories of modern medicine. However, too many implants fail prematurely, mainly due to aseptic bone loss around the implant. This paper reviews our current understanding of the role of osteoclasts in this peri-implant bone lysis. Prosthetic particles, often produced by articulating prostheses, are one of the major causes of elevated osteoclast lysis of peri-implant bone. Over the past decade there have been major advances in our understanding of the factors that regulate osteoclast activity, many of which were found to be important in osteoclast formation and activity in the peri-implant tissues. These factors are targets of a number of recently developed drugs that have been used successfully to prevent and treat peri-implant bone lysis in experimental models. Treatments such as these are being used in a number of bone loss pathologies in humans and have the potential for successful treatment of peri-implant osteolysis. In addition, understanding how different biomaterials influence the expression of key osteoclastogenic factors may allow us to select biomaterials for implantation that will last the lifetime of the recipient.