Titanium particles in peri-implantitis: distribution, pathogenesis and prospects.

Peri-implantitis is one of the most important biological complications in the field of oral implantology. Identifying the causative factors of peri-implant inflammation and osteolysis is crucial for the disease's prevention and treatment. The underlying risk factors and detailed pathogenesis of peri-implantitis remain to be elucidated. Titanium-based implants as the most widely used implant inevitably release titanium particles into the surrounding tissue. Notably, the concentration of titanium particles increases significantly at peri-implantitis sites, suggesting titanium particles as a potential risk factor for the condition. Previous studies have indicated that titanium particles can induce peripheral osteolysis and foster the development of aseptic osteoarthritis in orthopedic joint replacement. However, it remains unconfirmed whether this phenomenon also triggers inflammation and bone resorption in peri-implant tissues. This review summarizes the distribution of titanium particles around the implant, the potential roles in peri-implantitis and the prevalent prevention strategies, which expects to provide new directions for the study of the pathogenesis and treatment of peri-implantitis.

Osteocytes directly regulate osteolysis via MYD88 signaling in bacterial bone infection.

The impact of bone cell activation on bacterially-induced osteolysis remains elusive. Here, we show that matrix-embedded osteocytes stimulated with bacterial pathogen-associated molecular patterns (PAMPs) directly drive bone resorption through an MYD88-regulated signaling pathway. Mice lacking MYD88, primarily in osteocytes, protect against osteolysis caused by calvarial injections of bacterial PAMPs and resist alveolar bone resorption induced by oral Porphyromonas gingivalis (Pg) infection. In contrast, mice with targeted MYD88 restoration in osteocytes exhibit osteolysis with inflammatory cell infiltration. In vitro, bacterial PAMPs induce significantly higher expression of the cytokine RANKL in osteocytes than osteoblasts. Mechanistically, activation of the osteocyte MYD88 pathway up-regulates RANKL by increasing binding of the transcription factors CREB and STAT3 to Rankl enhancers and by suppressing K48-ubiquitination of CREB/CREB binding protein and STAT3. Systemic administration of an MYD88 inhibitor prevents jawbone loss in Pg-driven periodontitis. These findings reveal that osteocytes directly regulate inflammatory osteolysis in bone infection, suggesting that MYD88 and downstream RANKL regulators in osteocytes are therapeutic targets for osteolysis in periodontitis and osteomyelitis.

Bacterial infections exacerbate myeloma bone disease.

Multiple myeloma is characterized by osteolytic lesions caused by reduced bone formation and activated bone resorption. An important feature of myeloma is a failure of bone healing after successful treatment. In this work, clinical studies indicated a highly positive correlation between bone marrow bacteria abundance and bone lesion numbers of myeloma patients in complete remission. Coculture experiments demonstrated that marrow Escherichia coli (E. coli) promotes osteoclast differentiation and inhibits osteoblast differentiation. Mechanism studies showed that E. coli lipopolysaccharides (LPS) activated NF-κB p65 signaling and reduced phosphorylated smad1/5/9 binding ability with RUNX2 promoter, leading to decreased RUNX2 expression in osteoblast progenitors. Additionally, LPS enhanced phosphorylated NF-κB p65 binding ability with NFATc1 promoter, leading to increased NFATc1 expression in osteoclast progenitors. In vivo studies revealed E. coli contributes to osteolytic bone lesion, and elimination of E. coli infection assists healing of bone lesion in mouse model of myeloma in complete remission. These findings establish a heretofore unrecognized effect for E. coli in the genesis of myeloma bone disease and suggest a new treatment strategy.

Gorham Stout disease: 3 additional cases with 2 very rare polyostotic diseases.

Gorham Stout disease is a very rare monostotic or polyostotic osteolysis and physiopathology of the osteolysis is not yet fully understood. Three new cases are reported with their evolution and treatment. Among these 3 cases, two are very rare cases of polyostotic involvement. One patient finally deceased from respiratory complications despite limb amputation. The two others are alive. Both needed final reconstruction with massive bone allograft for one and with a prosthesis for the other. Monostotic osteolysis is the most frequent presentation of Gorham Stout disease and extensive polyostotic osteolysis is very rare. Treatment methods vary from one clinic to another, from drug treatment to surgical treatment with or without radiotherapy. Sometimes, as a last solution, an amputation of the affected limb is performed. The prognosis depends on the affected region and the reponse to various treatments. Chylothorax seems to be a factor of poor prognosis.

Management of Myeloma Bone Lesions.

Multiple myeloma (MM) is a B-cell neoplasm characterized by clonal plasma-cell proliferation. The survival and prognosis of this condition have been significantly improved by treatment with active anti-MM drugs such as bortezomib or lenalidomide. Further, the discovery of novel agents has recently paved the way for new areas of investigation. However, MM, including myeloma-related bone diseases, remains fatal. Bone disease or bone destruction in MM is a consequence of skeletal involvement with bone pain, spinal cord compression, and bone fracture resulting from osteolytic lesions. These consequences affect disease outcomes, including patients' quality of life and survival. Several studies have sought to better understand MM bone disease (MBD) through the classification of its molecular mechanisms, including osteoclast activation and osteoblast inhibition. Bisphosphonates and the receptor activator of the nuclear factor-kappa B (NF-κB) ligand (RANKL) inhibitor, denosumab, prevent skeletal-related events in MM. In addition, several other bone-targeting agents, including bone-anabolic drugs, are currently used in preclinical and early clinical evaluations. This review summarizes the current knowledge of the pathogenesis of MBD and discusses novel agents that appear very promising and will soon enter clinical development.

Large Lytic Defects Produce Kinematic Instability and Loss of Compressive Strength in Human Spines: An in Vitro Study.

BACKGROUND: In patients with spinal metastases, kinematic instability is postulated to be a predictor of pathologic vertebral fractures. However, the relationship between this kinematic instability and the loss of spinal strength remains unknown. METHODS: Twenty-four 3-level thoracic and lumbar segments from 8 cadaver spines from female donors aged 47 to 69 years were kinematically assessed in axial compression (180 N) and axial compression with a flexion or extension moment (7.5 Nm). Two patterns of lytic defects were mechanically simulated: (1) a vertebral body defect, corresponding to Taneichi model C (n = 13); and (2) the model-C defect plus destruction of the ipsilateral pedicle and facet joint, corresponding to Taneichi model E (n = 11). The kinematic response was retested, and compression strength was measured. Two-way repeated-measures analysis of variance was used to test the effect of each model on the kinematic response of the segment. Multivariable linear regression was used to test the association between the kinematic parameters and compressive strength of the segment. RESULTS: Under a flexion moment, and for both models C and E, the lesioned spines exhibited greater flexion range of motion (ROM) and axial translation than the control spines. Both models C and E caused lower extension ROM and greater axial, sagittal, and transverse translation under an extension moment compared with the control spines. Two-way repeated-measures analysis revealed that model E, compared with model C, caused significantly greater changes in extension and torsional ROM under an extension moment, and greater sagittal translation under a flexion moment. For both models C and E, greater differences in flexion ROM and sagittal translation under a flexion moment, and greater differences in extension ROM and in axial and transverse translation under an extension moment, were associated with lower compressive strength of the lesioned spines. CONCLUSIONS: Critical spinal lytic defects result in kinematic abnormalities and lower the compressive strength of the spine. CLINICAL RELEVANCE: This experimental study demonstrates that lytic foci degrade the kinematic stability and compressive strength of the spine. Understanding the mechanisms for this degradation will help to guide treatment decisions that address inferred instability and fracture risk in patients with metastatic spinal disease.

Mechanical loading attenuates breast cancer-associated bone metastasis in obese mice by regulating the bone marrow microenvironment.

Breast cancer, a common malignancy for women, preferentially metastasizes to bone and obesity elevates the chance of its progression. While mechanical loading can suppress obesity and tumor-driven osteolysis, its effect on bone-metastasized obese mice has not been investigated. Here, we hypothesized that mechanical loading can lessen obesity-associated bone degradation in tumor-invaded bone by regulating the fate of bone marrow-derived cells. In this study, the effects of mechanical loading in obese mice were evaluated through X-ray imaging, histology, cytology, and molecular analyses. Tumor inoculation to the tibia elevated body fat composition, osteolytic lesions, and tibia destruction, and these pathologic changes were stimulated by the high-fat diet (HFD). However, mechanical loading markedly reduced these changes. It suppressed osteoclastogenesis by downregulating receptor activator of nuclear factor Kappa-B ligand and cathepsin K and promoted osteogenesis, which was associated with the upregulation of OPG and downregulation of C/enhancer-binding protein alpha and proliferator-activated receptor gamma for adipogenic differentiation. Furthermore, it decreased the levels of tumorigenic genes such as Rac1, MMP9, and interleukin 1ß. In summary, this study demonstrates that although a HFD aggravates bone metastases associated with breast cancer, mechanical loading significantly protected tumor-invaded bone by regulating the fate of bone marrow-derived cells. The current study suggests that mechanical loading can provide a noninvasive, palliative option for alleviating breast cancer-associated bone metastasis, in particular for obese patients.

No differences between conservative and surgical management of acromioclavicular joint osteoarthritis: a scoping review.

PURPOSE: To conduct a scoping review to clarify the management of acromioclavicular joint osteoarthritis, as well as to identify any existing gaps in the current knowledge. METHODS: Studies were identified by electronic databases (Ovid, Pubmed) from their inception up to April 2nd, 2020. All studies reporting functional outcomes after conservative or surgical treatment of acromioclavicular joint osteoarthritis, either primary or secondary to trauma or distal clavicle osteolysis, were included. Following data were extracted: authors, year of publication, study design (prospective or retrospective), LOE, number of shoulders treated conservatively or surgically, patients' age, OA classification, type of conservative treatment, surgical approach, surgical technique, functional outcomes, complications, revisions, and length of follow-up. Descriptive statistics was used. Quality appraisal was assessed through the Cochrane risk of bias tool for LOE I/II studies, while the MINORS checklist was used for LOE III/IV studies. RESULTS: Nineteen studies were included for a total of 861 shoulders. Mean age of participants was 48.5 ± 7.4 years. Mean follow-up was 43.8 ± 29.9 months. Four studies reported functional results after conservative treatment, whereas 15 studies were focused on surgical management. No studies directly compared conservative and surgical treatment. Seven studies reported a surgical approach after failure of previous conservative treatment. All studies reported functional improvement and pain relief. Complication rate was low. Overall methodological quality of included studies was very low. CONCLUSION: Conservative and surgical treatments are both effective in acromioclavicular joint osteoarthritis management. However, available data did not allow to establish the superiority of one technique over another. LEVEL OF EVIDENCE: Level IV.

Hypercalcemia and Disseminated Osteolytic Lesions With Normal Blood Counts and Absence of Circulating Blasts: A Rare Presentation of Childhood B-Lymphoblastic Leukemia.

Hypercalcemia and disseminated osteolytic bone lesions are a rare presentation of pediatric acute lymphoblastic leukemia (ALL). The authors report a 3-year-old boy who presented with hypercalcemia and diffuse osteolytic lesions involving axial and appendicular bones. He had normal complete blood count and the absence of blasts in peripheral smear; however, bone marrow aspirate and trephine were consistent with B-cell ALL. A review of the literature highlights the variable clinical outcome of this rare presentation depending on the presence of hypercalcemia and osteolytic lesions with or without chromosomal translocation t(17;19) and coagulation abnormalities. The patient had no coagulopathy and normal karyotype, and showed excellent response to initial treatment in terms of complete remission and negative minimal residual disease after standard-risk induction chemotherapy. Hypercalcemia with diffuse osteolytic lesions warrants bone marrow examination to rule out leukemia even in the absence of any abnormality in complete blood count. The case was reported for awareness of this rare presentation of ALL so that delays can be avoided for this potentially curable but life-threatening disease.

Controversies in the use of new bone-modifying therapies in multiple myeloma.

Bone-modifying therapies are essential in the treatment of patients with multiple myeloma. Zoledronic acid is preferred over other bisphosphonates due to its superiority in reducing the incidence of skeletal-related events and improving survival. The anti-receptor activator of nuclear factor-κΒ ligand (RANKL)-targeted agent denosumab has shown its non-inferiority compared to bisphosphonates in preventing skeletal-related events among newly diagnosed patients with myeloma bone disease. Denosumab may confer a survival benefit in patients eligible for autologous transplantation. Denosumab may present a safer profile for patients with renal impairment. Discontinuation of bone-directed therapies can be considered for patients with deep responses and after an adequate time period on treatment; however, a rebound effect may become evident especially in the case of denosumab. Three-monthly infusions of zoledronic acid or at-home denosumab administration should be considered during the coronavirus disease 2019 (COVID-19) pandemic. Measures to prevent hypocalcaemia, renal toxicity and osteonecrosis of the jaw are important for all bone-modifying agents.

Salvage of Distal Femoral Replacement Loosening with Massive Osteolysis Using Impaction Grafting: A Report of 2 Cases.

CASE: Salvage of 2 cases of distal femoral replacement loosening with massive osteolysis using impaction grafting are presented with 9- and 11-year follow-ups. CONCLUSION: Surgeons should keep impaction grafting in their armamentarium for cases of failed DFR with severe osteolysis. Doing so may allow for preservation of the native hip and deferment of more radical procedures (i.e. total femur replacement) that have high rates of complication and poor survivorship.

Puerarin inhibits titanium particle-induced osteolysis and RANKL-induced osteoclastogenesis via suppression of the NF-κB signaling pathway.

Osteolysis around the prosthesis and subsequent aseptic loosening are the main causes of prosthesis failure. Inflammation due to wear particles and osteoclast activation are the key factors in osteolysis and are also potential targets for the treatment of osteolysis. However, it is not clear whether puerarin can inhibit chronic inflammation and alleviate osteolysis. In this study, we investigated the effect of puerarin on Ti particle-induced inflammatory osteolysis in vivo in rat femoral models and in vitro in receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclast activation models. Our in vivo results showed that puerarin significantly inhibited Ti particle-induced osteolysis and the expression of matrix metallopeptidase 9 (MMP-9), nuclear factor of activated T cells 1 (NFATc1), tumour necrosis factor (TNF)-α and interleukin (IL)-6. In vitro, puerarin prevented RANKL-induced osteoclast differentiation, bone resorption and F-actin ring formation in a concentration-dependent manner. Furthermore, puerarin decreased the phosphorylation of p65 and prevented p65 moving from the cytoplasm to the nucleus. Puerarin also reduced the expression of osteoclast-specific factors and inhibited the inflammatory response. In conclusion, our study proves that puerarin can block the NF-κB signalling pathway to inhibit osteoclast activation and inflammatory processes, which provides a new direction for the treatment of osteolysis-related diseases.

Paraparesis and Disseminated Osteolytic Lesions Revealing Cholangiocarcinoma: A Case Report.

Bone metastases in cholangiocarcinoma are uncommon. We report the case of a patient with disseminated osteolytic lesions who was admitted to the Neurology Department for progressive paraparesis. On the computed tomography examination, specific features for cholangiocarcinoma were described, confirmed later by the histopathological aspect of the bone lesions.

Nonoperative Treatment of a Pathologic Proximal Tibia Fracture in the Setting of Previous Total Knee Arthroplasty: A Case Report.

CASE: We present the case of a super obese 51-year-old woman with a pathologic fracture of the proximal tibia in the setting of a previous total knee arthroplasty. Imaging demonstrated an osteolytic lesion distal to the keel and pathologic fracture of the proximal tibia. Nonoperative treatment with a 12-week course of nonweight-bearing resulted in fracture healing and ossification of osteolysis. CONCLUSION: Pathologic fractures of the tibia secondary to osteolysis are frequently treated surgically. Patients may benefit from nonoperative management, even in the setting of super morbid obesity and significant osteolysis about the tibial component.

[Low-grade-infections after spondylodeses-A chameleon? : Current findings and therapeutic strategies]. / Low-Grade-Infektionen in der Wirbelsäulenchirurgie ­ Ein Chamäleon? : Neuste Erkenntnisse und Behandlungsstrategien.

BACKGROUND: Low-grade infections are caused by low-virulence pathogens. The course of these infections is often mild, which is why they are often delayed or not recognized at all. Chronic infections can lead to osteolysis and implant loosening. The rate of complications requiring revision, such as implant loosening or material failure, is known from the literature. However, the rate of low-grade infections in patients requiring spinal revision surgery remains unclear. PURPOSE: The aim of this review is to present the latest treatment strategies for low-grade infections. The diagnostic and therapeutic options are summarized in the form of algorithms. The aim of this work is to raise an awareness of the possibility of a low-grade infection in patients undergoing spinal revision surgery. MATERIALS AND METHODS: Review of the literature RESULTS: The detection of low-grade infections is difficult from both a clinical and a radiological point of view. In the event of unexplained implant loosening or failure despite the lack of local inflammatory signs and often normal laboratory parameters, a low-grade infection must be considered. Multiple microbiological sampling must be requested as part of the revision surgery. A histological examination is recommended for all revision surgery, especially if a low-grade infection is suspected. The diagnosis should ideally be completed by sonicating the implants with subsequent microbiological incubation of the preserved samples. If a low-grade infection is suspected, the biofilm-covered implant should be removed or replaced if instability/no fusion is present. The use of topical antibiotics could be useful, but its effectiveness in treating low-grade infections has not yet been sufficiently demonstrated. DISCUSSION: An algorithm for clinical decision-making in terms of diagnostic and therapeutic options is suggested.

Life-threatening hypophosphataemia secondary to zoledronic acid implementation in a middle-age patient who presented with advanced osteolysis in the course of multiple myeloma.

Not required for Clinical Vignette.

Curcumin has immunomodulatory effects on RANKL-stimulated osteoclastogenesis in vitro and titanium nanoparticle-induced bone loss in vivo.

Wear particle-stimulated inflammatory bone destruction and the consequent aseptic loosening remain the primary causes of artificial prosthesis failure and revision. Previous studies have demonstrated that curcumin has a protective effect on bone disorders and inflammatory diseases and can ameliorate polymethylmethacrylate-induced osteolysis in vivo. However, the effect on immunomodulation and the definitive mechanism by which curcumin reduces the receptor activators of nuclear factor-kappa B ligand (RANKL)-stimulated osteoclast formation and prevents the activation of osteoclastic signalling pathways are unclear. In this work, the immunomodulation effect and anti-osteoclastogenesis capacities exerted by curcumin on titanium nanoparticle-stimulated macrophage polarization and on RANKL-mediated osteoclast activation and differentiation in osteoclastic precursor cells in vitro were investigated. As expected, curcumin inhibited RANKL-stimulated osteoclast maturation and formation and had an immunomodulatory effect on macrophage polarization in vitro. Furthermore, studies aimed to identify the potential molecular and cellular mechanisms revealed that this protective effect of curcumin on osteoclastogenesis occurred through the amelioration of the activation of Akt/NF-κB/NFATc1 pathways. Additionally, an in vivo mouse calvarial bone destruction model further confirmed that curcumin ameliorated the severity of titanium nanoparticle-stimulated bone loss and destruction. Our results conclusively indicated that curcumin, a major biologic component of Curcuma longa with anti-inflammatory and immunomodulatory properties, may serve as a potential therapeutic agent for osteoclastic diseases.

A CARE-compliant article: A case report of scoliosis complicated with multicentric carpotarsal osteolysis.

RATIONALE: Multicentric carpotarsal osteolysis (MCTO) is a rare hereditary disease caused by mutations in MafB, a negative regulator of osteoclastogenesis. PATIENT CONCERNS: A 20-year-old, Japanese woman with scoliosis visited our institute for treatment. Scoliosis was apparent since she was 12 years old, but she had not sought treatment until the age of 19. Medical examination showed a typical facial appearance associated with a small forehead and hypotelorism; shortening of the fingers of both hands and both upper limbs was observed, in addition to clubfoot. No café au lait spots or mental retardation were observed. On the other hand, the trunk showed evidence of an irregular waistline and a rib hump that obviously suggested scoliosis. Neurological deficit was not observed. Spirometry showed decreased forced vital capacity (FVC). Although proteinuria was observed, renal dysfunction and hypertension were not seen. The major curve of scoliosis was 82° (MC, Th7-L2; Th11 apical vertebra), and the upper curve was 77° (UC, Th1-6; Th3 apical vertebra). In a recumbent-traction position, the major curve was 54° and the upper curve was 56°. The pelvic incidence minus lumbar lordosis (PI-LL) angle was <10° and no mismatch was observed; thoracic kyphosis was decreased to 16°. DIAGNOSIS: The patient was diagnosed with symptomatic scoliosis secondary to MCTO. INTERVENTIONS: We decided to perform a correction and fusion from Th2 to L3 using a posterior spinal instrumentation. OUTCOMES: Postoperative x-ray demonstrated scoliosis angle correction from 77° to 38° at Th1-6 and 82° to 39° at Th7-L2. Postoperative x-ray demonstrated thoracic kyphosis angle correction from 16° to 21°. The patient's height increased from 155 to 161 cm. LESSONS: It has been 24 months since the operation, and no exacerbation has been observed. To the best of our knowledge, this is the first report of surgical treatment of scoliosis secondary to MCTO.

Unusual form of the distal bone defect of ulna with neurofibromatosis type 1: A case report.

RATIONALE: Bone malformation occurs in 10% to 25% neurofibromatosis type 1 (NF-1) patients, and the manifestations are scoliosis, congenital arch and pseudo-joint formation, bone cyst, and pathologic fracture. However, a large segmental defect without obvious signs of bone destruction has rarely been reported. PATIENT CONCERNS: A 4.5-year-old male presented with a 4-year history of shortening of the right upper limb and radial head dislocation. The X-ray indicated a lack of the distal part of the right ulna and radial head dislocation. DIAGNOSIS: The X-ray showed obvious bone resorption at the right ulna distal, proximal stubble, and distal part of the epiphyseal residue, which was 4.3 mm shorter after 14 months. The patient was finally diagnosed with NF-1 according to the pathologic examination. INTERVENTIONS: The treatment included tumor resection, ulnar osteotomy, and fixation by an Ilizarov frame. OUTCOMES: The Ilizarov frame was removed after 2.7 months of surgery. The radial head was successfully repositioned, and the elbow joint function was significantly improved. No recurrence of the deformity was noted until now. LESSONS: Osteolysis (defect without bone destruction) is an extremely rare symptom in patients with NF1. Therefore, it is essential to make the right diagnosis by comprehensive and careful physical examination.