Discovery of biomarkers to identify peri-implant osteolysis before radiographic diagnosis

Spinal implant wear particles: Generation, characterization, biological impacts, and future considerations

The generation of wear debris from orthopedic implants is a known cause of implant failure, particularly in joint replacements. While much research has focused on wear particles from knee and hip implants, spinal implants, such as total disc replacements (TDRs), have received less attention despite their increasing clinical use. Spinal implants face unique biomechanical challenges, including a wider range of motion and higher loads, leading to complex tissue interactions. Studies reveal that TDR wear particles, though similar in size to those from knee implants, cause a stronger immune response, with more macrophages and giant cells found in the surrounding tissue. This may explain the high revision rates seen in spinal surgeries, with some interventions failing in over 30% of cases within 10 years. The younger population undergoing spinal surgery, combined with the productivity losses associated with implant failure, underscores the need for greater understanding. This review discusses recent research on the generation, characterization, and biological impacts of spinal implant wear debris. It draws on retrieval analysis, wear simulation, in vivo models, and a survey conducted with the AO Spine Knowledge Forum Degenerative to assess current clinical practices and highlight gaps in knowledge. Additionally, this critical review explores future strategies to reduce the biological impact of wear particles and improve the safety and longevity of spinal implants through better therapeutics and design innovations. By combining literature and clinical insights, this paper aims to guide future research in addressing the complexities of spinal implant wear and its biological consequences.

Osteoblasts-derived exosomes as potential novel communicators in particle-induced periprosthetic osteolysis

The inflammatory response to wear particles derived from hip prothesis is considered a hallmark of periprosthetic osteolysis, which can ultimately lead to the need for revision surgery. Exosomes (Exos) have been associated with various bone pathologies, and there is increasing recognition in the literature that they actively transport molecules throughout the body. The role of wear particles in osteoblast-derived Exos is unknown, and the potential contribution of Exos to osteoimmune communication and periprosthetic osteolysis niche is still in its infancy. Given this, we investigate how titanium dioxide nanoparticles (TiO2 NPs), similar in size and composition to prosthetic wear particles, affect Exos biogenesis. Two osteoblastic cell models commonly used to study the response of osteoblasts to wear particles were selected as a proof of concept. The contribution of Exos to periprosthetic osteolysis was assessed by functional assays in which primary human macrophages were stimulated with bone-derived Exos. We demonstrated that TiO2 NPs enter multivesicular bodies, the nascent of Exos, altering osteoblast-derived Exos secretion and molecular cargo. No significant differences were observed in Exos morphology and size. However, functional assays reveal that Exos cargo enriched in uPA stimulates macrophages to a mixed M1 and M2 phenotype, inducing the release of pro- and anti-inflammatory signals characteristic of periprosthetic osteolysis. In addition, we demonstrated the expression of uPA in exosomes derived from the urine of patients with osteolysis. These results suggest that uPA can be a potential biomarker of osteolysis. In the future, uPa may serve as a possible non-invasive biomarker to identify patients at risk for peri-implant osteolysis.

Biomarkers to discriminate between aseptic loosened and stable total hip or knee arthroplasties: a systematic review

Background

Loosening is a major cause for failure of total hip and total knee arthroplasties (THAs/TKAs). Preemptive diagnostics of asymptomatic loosening could open strategies to prevent gross loosening. A multitude of biomarkers may discriminate between loosened and stable implants, but it is unknown which have the best performance. The present systematic review aimed to assess which biomarkers have shown the most promising results in discriminating between stable and aseptic loosened THAs and TKAs.

Methods

PubMed, Embase, Web of Science, Cochrane Library, and Academic Search Premier were systematically searched up to January 2020 for studies including THA/TKA and biomarkers to assess loosening. Two reviewers independently screened records, extracted data, and assessed the risk of bias using the ICROMS tool to classify the quality of the studies.

Results

Twenty-eight (three high-quality) studies were included, reporting on a median of 48 patients (interquartile range 28-69). Serum and urine markers were evaluated in 22 and 10 studies, respectively. Tumor necrosis factor α and osteocalcin were significantly higher in loosened compared with stable implants. Urinary N-terminal telopeptide had significantly elevated levels in loosened prostheses.

Conclusion

Several serum and urine markers were promising in discriminating between loosened and stable implants. We recommend future studies to evaluate these biomarkers in a longitudinal fashion to assess whether progression of loosening is associated with a change in these biomarkers. In particular, high-quality studies assessing the usability of these biomarkers are needed.

Zucker Diabetic-Sprague Dawley Rats Have Impaired Peri-Implant Bone Formation, Matrix Composition, and Implant Fixation Strength

An increasing number of patients with type 2 diabetes (T2DM) will require total joint replacement (TJR) in the next decade. T2DM patients are at increased risk for TJR failure, but the mechanisms are not well understood. The current study used the Zucker Diabetic-Sprague Dawley (ZDSD) rat model of T2DM with Sprague Dawley (SPD) controls to investigate the effects of intramedullary implant placement on osseointegration, peri-implant bone structure and matrix composition, and fixation strength at 2 and 10 weeks post-implant placement. Postoperative inflammation was assessed with circulating MCP-1 and IL-10 2 days post-implant placement. In addition to comparing the two groups, stepwise linear regression modeling was performed to determine the relative contribution of glucose, cytokines, bone formation, bone structure, and bone matrix composition on osseointegration and implant fixation strength. ZDSD rats had decreased peri-implant bone formation and reduced trabecular bone volume per total volume compared with SPD controls. The osseointegrated bone matrix of ZDSD rats had decreased mineral-to-matrix and increased crystallinity compared with SPD controls. Osseointegrated bone volume per total volume was not different between the groups, whereas implant fixation was significantly decreased in ZDSD at 2 weeks but not at 10 weeks. A combination of trabecular mineral apposition rate and postoperative MCP-1 levels explained 55.6% of the variance in osseointegration, whereas cortical thickness, osseointegration mineral apposition rate, and matrix compositional parameters explained 69.2% of the variance in implant fixation strength. The results support the growing recognition that both peri-implant structure and matrix composition affect implant fixation and suggest that postoperative inflammation may contribute to poor outcomes after TJR surgeries in T2DM patients. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Titanium dioxide nanoparticles affect osteoblast-derived exosome cargos and impair osteogenic differentiation of human mesenchymal stem cells

Titanium (Ti) and its alloys are the most widely used metallic biomaterials in total joint replacement; however, increasing evidence supports the degradation of its surface due to corrosion and wear processes releasing debris (ions, and micro and nanoparticles) and contribute to particle-induced osteolysis and implant loosening. Cell-to-cell communication involving several cell types is one of the major biological processes occurring during bone healing and regeneration at the implant-bone interface. In addition to the internal response of cells to the uptake and intracellular localization of wear debris, a red flag is the ability of titanium dioxide nanoparticles (mimicking wear debris) to alter cellular communication with the tissue background, disturbing the balance between osseous tissue integrity and bone regenerative processes. This study aims to understand whether titanium dioxide nanoparticles (TiO₂ NPs) alter osteoblast-derived exosome (Exo) biogenesis and whether exosomal protein cargos affect the communication of osteoblasts with human mesenchymal stem/stromal cells (HMSCs). Osteoblasts are derived from mesenchymal stem cells coexisting in the bone microenvironment during development and remodelling. We observed that TiO₂ NPs stimulate immature osteoblast- and mature osteoblast-derived Exo secretion that present a distinct proteomic cargo. Functional tests confirmed that Exos derived from both osteoblasts decrease the osteogenic differentiation of HMSCs. These findings are clinically relevant since wear debris alter extracellular communication in the bone periprosthetic niche, contributing to particle-induced osteolysis and consequent prosthetic joint failure.

The Role of the Innate Immune System in Wear Debris-Induced Inflammatory Peri-Implant Osteolysis in Total Joint Arthroplasty

Periprosthetic osteolysis remains a leading complication of total hip and knee arthroplasty, often resulting in aseptic loosening of the implant and necessitating revision surgery. Wear-induced particulate debris is the main cause initiating this destructive process. The purpose of this article is to review recent advances in understanding of how wear debris causes osteolysis, and emergent strategies for the avoidance and treatment of this disease. A strong activator of the peri-implant innate immune this debris-induced inflammatory cascade is dictated by macrophage secretion of TNF-α, IL-1, IL-6, and IL-8, and PGE2, leading to peri-implant bone resorption through activation of osteoclasts and inhibition of osteoblasts through several mechanisms, including the RANK/RANKL/OPG pathway. Therapeutic agents against proinflammatory mediators, such as those targeting tumor necrosis factor (TNF), osteoclasts, and sclerostin, have shown promise in reducing peri-implant osteolysis in vitro and in vivo; however, radiographic changes and clinical diagnosis often lag considerably behind the initiation of osteolysis, making timely treatment difficult. Considerable efforts are underway to develop such diagnostic tools, therapies, and identify novel targets for therapeutic intervention.

Comparison of Bone Turnover Biomarkers in Serum and Urine Measured on an Automated Analytical Platform

BACKGROUND

Matched serum and urine samples from patients who had total hip replacement were used to assess serum-validated immunoassay reagents for use in urine.

METHODS

Samples were evaluated by an automated electrochemiluminescent immunoassay (cobas e411; Roche Diagnostics) for C-terminal telopeptide of type I collagen isoform β (β-Crosslaps), osteocalcin N-terminal midfragment (N-MID OC), N-terminal propeptide of type I collagen (PINP), and interleukin 6 (IL-6). Spike and recovery experiments were utilized to assess urinary matrix effects. Correlations between serum and both raw and creatinine-corrected urinary measures were assessed. Short-term precision was assessed.

RESULTS

Spike and recovery experiments indicated minimal matrix effects of urine for the β-Crosslaps assay. Potential matrix effects were observed for the other analytes because N-MID OC and IL-6 tended to be slightly overrecovered, whereas PINP was underrecovered. There were strong correlations between serum β-Crosslaps and raw (Spearman ρ [rs] = 0.725, P < 0.0001) and creatinine-corrected (rs = 0.793, P < 0.0001) urinary measures and moderate correlations between serum N-MID OC and raw (rs = 0.582, P < 0.0001) and creatinine-corrected (rs = 0.482, P < 0.0001) urinary measures. PINP was not detected in urine, and no significant serum-urine correlations were found for IL-6. Short-term precision for urinary levels of β-Crosslaps, N-MID OC, and IL-6 were 1.6%, 6.3% and 14.4%, respectively.

CONCLUSIONS

Urinary measurements of β-Crosslaps and N-MID OC assays were correlated with serum measurements and had good short-term precision. Urinary PINP was not detectable. IL-6 can be measured in urine using this technology, but the levels did not correlate with serum levels, and the short-term precision was variable.

Effect of Interleukin 1 Receptor Antagonist Gene on Stable Expression Bone Marrow Mesenchymal Stem Cells and Early Aseptic Loosening of Hip Prosthesis of Mouse

The research aimed to investigate the diagnostic value of Interleukin 1 receptor antagonist (IL-1Ra) in the early aseptic loosening of hip prosthesis and whether IL-1Ra can be expressed in bone marrow mesenchymal stem cells. In this study, the IL-1Ra gene was firstly connected to the lentiviral vector LV5, and the lentiviral vector LV5-home-IL1Ra was obtained by recombination. Then the recombinant LV5-home-IL1Ra was co-transfected with the virus-assisted plasmid into 293 T cells and packaged to produce lentivirus. Bone marrow-derived stem cells (BMSCs) were infected with packaged lentiviruses. The relative expression of IL-1Ra mRNA in BMSCs was detected by fluorescence quantitative PCR. The expression of IL-1Ra protein in BMSCs was detected by western blot transfer electrophoresis. Peripheral venous blood samples from 108 patients and healthy subjects underwent total hip replacement were collected to detect the levels of plasma biomarkers procollagen type I carboxy-terminal propeptide (PICP), N-telopeptide cross-links of type I collagen (NTX), osteoprotegerin (OPG), TNGα, receptor activator of NF-kappaB ligand (RANKL), and IL-1β. The recombinant lentivirus vector IL-1Ra was successfully constructed by 2% agarose gel electrophoresis. Lentivirus-mediated IL-1Ra gene could efficiently transfection bone marrow mesenchymal stem cells, and the cell growth density reached about 80% at 72 h after infection. The transfection rate was about 90%, and the fluorescence was enhanced. The relative mRNA and protein expression levels of IL-1Ra in the BMSCs-IL-1Ra group were significantly higher than those in the BMSCs group and the BMSCs-con group (P < 0.01). The late loosening group of IL-1β was significantly higher than the stable prosthesis group and the healthy group (P < 0.05). The ROC curve showed that IL-1 background had strong diagnostic sensitivity and specificity, which was similar to the X-ray score of osteolysis and had the most significant diagnostic significance. Lentivirus-transfected exogenous IL-1Ra can be expressed stably in mouse bone marrow mesenchymal stem cells, and IL-1β, an antagonist of IL-1Ra, plays an important role in the early aseptic loosening of hip prosthesis.

Biomechanics of Implant Fixation in Osteoporotic Bone

PURPOSE OF REVIEW

The purpose of this review is to critically evaluate the current literature regarding implant fixation in osteoporotic bone.

RECENT FINDINGS

Clinical studies have not only demonstrated the growing prevalence of osteoporosis in patients undergoing total joint replacement (TJR) but may also indicate a significant gap in screening and treatment of this comorbidity. Osteoporosis negatively impacts bone in multiple ways beyond the mere loss of bone mass, including compromising skeletal regenerative capacity, architectural deterioration, and bone matrix quality, all of which could diminish implant fixation. Recent findings both in preclinical animal models and in clinical studies indicate encouraging results for the use of osteoporosis drugs to promote implant fixation. Implant fixation in osteoporotic bone presents an increasing clinical challenge that may be benefitted by increased screening and usage of osteoporosis drugs.

Usefulness of 99mTc-ASC lymphoscintigraphy and SPECT/CT in the evaluation of rare lymphatic disorders: Gorham-Stout disease, lymphangioma, and lymphangioleiomyomatosis

The purpose of this study was to investigate the role of Tc-antimony sulfide colloid (ASC) lymphoscintigraphy and single photon emission computed tomography/computed tomography (SPECT/CT) in the evaluation of rare lymphatic disorders, including Gorham--Stout disease (GSD), lymphangioma, and lymphangioleiomyomatosis (LAM).Nine patients suspected to have rare lymphatic disorders were included in this retrospective study. All patients underwent Tc-ASC lymphoscintigraphy and SPECT/CT to evaluate the lesions. The lymphoscintigraphy results were compared with the clinical and immunopathological findings.Tc-ASC lymphoscintigraphy and SPECT/CT could provide lymphatic draining and anatomical information for rare lymphatic disorders. Among the 9 patients, 3 were diagnosed with GSD (1 female, 2 males; aged 15-34 years, range 27.0 ± 10.4 years), 3 with lymphangioma (1 female, 2 males; aged 17-42 years, range 32.0 ± 13.2 years), and 3 patients were diagnosed with LAM (3 females; aged 33-50 years, range 43.7 ± 9.3 years]. GSD is characterized by multiple bone destruction, including spine, ribs, ilium, pubis, ischium, and femur. The tracer uptake of involved bones and soft tissue around bone is increased, accompanied by chylothorax, chylopericardium, and chylous leakage in abdominal and pelvic cavity. Lymphangiomas present as multiple cystic lesions with increased tracer uptake in the peripancreatic, retroperitoneal, and iliac areas, and in the abdominopelvic cavity. LAM presents as multiple thin-walled cysts in the bilateral lungs and multiple retroperitoneal enlarged lymph nodes with increased tracer uptake.Tc-ASC lymphoscintigraphy and SPECT/CT could comprehensively and specifically detect some rare lymphatic disorders, namely, GSD, lymphangioma, and LAM. This technique is useful for the evaluation of GSD, lymphangioma, and LAM.

Early changes in serum osteocalcin and body weight are predictive of implant fixation in a rat model of implant loosening

Biomarkers are of interest to identify patients at risk for peri-implant osteolysis and aseptic loosening. We used a rat model of particle-induced peri-implant osteolysis to investigate if early changes in biomarkers were associated with subsequent implant fixation strength. Implants were placed in rat femora, which were then challenged with intra-articular knee injections of either clean polyethylene, lipopolysaccharide-doped polyethylene, or cobalt-chromium alloy particles, with particle-free vehicle serving as control (n ≥ 8 per group). Rats were weighed weekly, blood was collected at weeks 0, 3, 5, and 6, and locomotor behavior was assessed 4 days before study conclusion. Rats were euthanized 6 weeks post surgery. Week 6 serum was analyzed for five bone remodeling markers, while longitudinal serum was assessed for osteocalcin. Bone-implant contact, peri-implant trabecular architecture, and implant fixation strength were measured. Rats challenged with cobalt-chromium particles had a significant reduction in implant fixation strength compared with the vehicle-control group (P = .034). This group also had elevated serum osteocalcin (P = .005), depressed weight gain (P = .001) and less frequent rearing behavior (P = .029). Regardless of group, change in serum osteocalcin at week 3 (r = -.368; P = .046), change in weight at week 2 (r = .586; P < .001), as well as weight change at all other time intervals were associated with fixation strength. The finding that early alterations in serum osteocalcin and body weight were predictive of subsequent implant fixation strength supports continued investigation of biomarkers for early detection of peri-implant osteolysis and implant loosening. Further, change in biomarker levels was found to be more indicative of implant fixation status than any single measurement.