AGN1 implant material to treat bone loss: Resorbable implant forms normal bone with and without alendronate in a canine critical size humeral defect model

AGN1 local osteo-enhancement procedure increases proximal femur volumetric bone mineral density of women with post-menopausal osteoporosis as assessed by quantitative computed tomography analysis

In this study, QCT was used to analyze the AGN1 Local Osteo-Enhancement Procedure (LOEP) as a treatment to form bone in the proximal femurs of patients with osteoporosis. Using this minimally invasive procedure, a resorbable triphasic AGN1 implant material was injected into the left femurs of 12 women with post-menopausal osteoporosis. Computed tomography scans were taken before treatment (baseline) and at 12 wk, 24 wk, and 5-7 yr after treatment. Quantitative computed tomography was used to investigate the resorption of AGN1 within the treated proximal femurs and to analyze the treatment's impact on integral, trabecular, and cortical bone. The untreated right femurs were used as controls. Data illustrated an increase in trabecular volumetric BMD (trab vBMD) of treated hips at all timepoints (baseline: 22 ± 21 mg/cm3 vs 217 ± 56 mg/cm3, 161 ± 18 mg/cm3, and 121 ± 37 mg/cm3 at 12-wk, 24-wk, and 5- to 7-yr timepoints, respectively), and an increase in integral vBMD of 65% at the 12-wk timepoint and 34% at the 5- to 7-yr timepoint. The increase in trab vBMD was observed in the location where the AGN1 implant material bolus was injected, and at the 5- to 7-yr timepoint, no significant BMD change was observed in the trabecular regions surrounding the original implantation zone (treated: 32 ± 16 mg/cm3, control: 31 ± 16 mg/cm3). This QCT study provides a more detailed understanding of the resorption and transformation of the AGN1 implant material into bone and supports, with some limitations, that the AGN1 LOEP treatment can locally increase trabecular bone density in weakened areas of the proximal femur where strength increase is most needed to reduce the risk of hip fragility fracture.

Combining systemic and local osteoporosis treatments: A longitudinal in vivo microCT study in ovariectomized rats

INTRODUCTION

Managing osteoporotic patients at immediate fracture risk is challenging, in part due to the slow and localized effects of anti-osteoporotic drugs. Combining systemic anti-osteoporotic therapies with local bone augmentation techniques offers a promising strategy, but little is known about potential interactions. We hypothesized that integrating systemic treatments with local bone-strengthening biomaterials would have an additive effect on bone density and structure. This study investigated interactions and synergies between systemic therapies and injectable biomaterials, HA2 and HA2-ZOL, designed for local bone strengthening. HA2-ZOL incorporates Zoledronate, a bisphosphonate, to enhance anti-resorptive effects. These materials were tested in an in vivo rat model of osteoporosis using microCT and histology.

METHODS

Thirty-six ovariectomized Wistar rats were treated systemically with vehicle (VEH), alendronate (ALN), or parathyroid hormone (PTH). One week later, their tibiae were randomly assigned to local treatment groups: HA2, HA2-ZOL, or NaCl control. Bilateral injections targeted metaphyseal trabecular bone, with microCT scans tracking changes over 8 weeks. Regions of interest (ROIs) were identified and analyzed for bone volume fraction (BV/TV), tissue mineral density (TMD), and trabecular morphology. Histological analyses were performed at week 8 to assess bone structure and mineral inclusions.

RESULTS

VEH animals with NaCl injections experienced marked bone loss, partially mitigated by ALN and PTH. HA2 injections increased BV/TV by factors of 2.5 to 3.4 across treatments compared to baseline, with effects confined to the injected material. HA2-ZOL amplified this response, with BV/TV increases up to 4.8-fold, particularly in VEH and PTH animals. The effects peaked at 2-4 weeks post-injection, followed by remodeling and restoration. Both local treatments increased trabecular thickness, with HA2-ZOL showing slower post-peak resorption.

DISCUSSION

HA2 injections significantly densified bone, independent of systemic therapy. Zoledronate in HA2-ZOL enhanced bone formation and delayed resorption in control and PTH animals, but offered no additional benefit when combined with systemic bisphosphonate. These findings support the hypothesis of an additive effect, suggesting that injectable hydrogels with localized drug delivery can complement systemic therapies by rapidly increasing local bone density, thereby potentially preventing fractures in high-risk osteoporotic patients.

Proximal femoral nailing for intertrochanteric fracture combined with contralateral femoral neck local osteo-enhancement procedure (LOEP) for severe osteoporotic bone loss: An original Italian case series

Proximal femoral fractures in elderly women are a major cause of morbidity and mortality worldwide and a public health concern. Although pharmacological therapies have shown potential in improving bone mineral density (BMD) and decreasing fracture risk, the current research effort is focused on developing a procedure that can ensure both immediate and long-term efficacy. A minimally-invasive surgical approach, known as AGN1 local osteo-enhancement procedure (LOEP), has been recently developed to promote bone augmentation. The procedure implies the preparation of an enhancement site, a specific location where new bone is required within a local bony area weakened by osteoporotic bone loss, and the insertion of a triphasic, resorbable, calcium-based implant material. The results of this procedure have shown a significant and sustainable long-term increase in the proximal femur BMD and consequently in bone strength, thereby improving the femoral neck's resistance to compression and distraction forces that may result in fall-related fractures. A preliminary case series of ten women, suffering from intertrochanteric fracture and contralateral proximal femur severe osteoporotic bone loss, who underwent a combined procedure of proximal femoral nailing and AGN1 local osteo-enhancement procedure, has been developed over the course of a year of clinical and radiological data collection.

Dual-Layer Spectral-Computed Tomography Enhances the Separability of Calcium-Based Implant Material from Bone: An Ex Vivo Quantitative Imaging Study

Local treatment of bone loss with an injection of a resorbable, calcium-based implant material to replace bone has a long history of clinical use. The in vivo discrimination of changes in bone versus implant is challenging with standard computed tomography (CT). However, spectral-CT techniques enable the separation between tissues of similar densities but different chemical compositions. Dual-layer spectral-CT imaging and postprocessing analysis methods were applied to investigate the separability of AGN1 (a triphasic calcium-based implant) and bone after AGN1 injection in n = 10 male cadaveric femurs ex vivo. Using the area under the curve (AUC) from receiver-operating characteristic (ROC) analyses, the separability of AGN1 from bone was assessed for AGN1 (postoperatively) versus compact and versus femoral neck cancellous bone (both preoperatively). CT techniques included conventional Hounsfield (HU) and density-equivalent units (BMD, mg hydroxyapatite [HA]/cm³ ) and spectral-CT measures of effective atomic number (Zeff) and electron density (ED). The samples had a wide range of femoral neck BMD (55.66 to 241.71 mg HA/cm³ ). At the injection site average BMD, HU, Zeff, and ED increased from 69.5 mg HA/cm³ , 109 HU, 104.38 EDW, and 8.30 Zeff in the preoperative to 1233 mg HA/cm³ , 1741 HU, 181.27 EDW, and 13.55 Zeff in the postoperative CT scan, respectively. For compact bone at the femoral shaft the preoperative values were 1124.15 mg HA/cm³ , 1648 HU, 177 EDW, and 13.06 Zeff and were maintained postoperatively. Zeff showed substantially sharper distributions and significantly greater separability compared to ED, BMD, and HU (all p < 0.002, for both regions) with average AUCs for BMD, HU, ED, and Zeff of 0.670, 0.640, 0.645, and 0.753 for AGN1 versus compact and 0.996, 0.995, 0.994, and 0.998 for AGN1 versus femoral neck cancellous sites, respectively. Spectral-CT permits better discrimination of calcium-based implants like AGN1 from bone ex vivo. Our results warrant application of spectral-CT in patients undergoing procedures with similar implants. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Research progress of bone-targeted drug delivery system on metastatic bone tumors

Bone metastases are common in malignant tumors and the effect of conventional treatment is limited. How to effectively inhibit tumor bone metastasis and deliver the drug to the bone has become an urgent issue to be solved. While bone targeting drug delivery systems have obvious advantages in the treatment of bone tumors. The research on bone-targeted anti-tumor therapy has made significant progress in recent years. We introduced the related tumor pathways of bone metastases. The tumor microenvironment plays an important role in metastatic bone tumors. We introduce a drug-loading systems based on different environment-responsive nanocomposites for anti-tumor and anti-metastatic research. According to the process of bone metastases and the structure of bone tissue, we summarized the information on bone-targeting molecules. Bisphosphate has become the first choice of bone-targeted drug delivery carrier because of its affinity with hydroxyapatite in bone. Therefore, we sought to summarize the bone-targeting molecule of bisphosphate to identify the modification effect on bone-targeting. And this paper discusses the relationship between bisphosphate bone targeting molecular structure and drug delivery carriers, to provide some new ideas for the research and development of bone-targeting drug delivery carriers. Targeted therapy will make a more outstanding contribution to the treatment of tumors.

Osteoporosis in 10 years time: a glimpse into the future of osteoporosis

Patients living with osteoporosis are projected to increase dramatically in the next decade. Alongside the forecasted increased societal and economic burden, we will live a crisis of fractures. However, we will have novel pharmacological treatment to face this crisis and, more importantly, new optimized treatment strategies. Fracture liaison services will be probably implemented on a large scale worldwide, helping to prevent additional fractures in high-risk patients. In the next decade, novel advances in the diagnostic tools will be largely available. Moreover, new and more precise fracture risk assessment tools will change our ability to detect patients at high risk of fractures. Finally, big data and artificial intelligence will help us to move forward into the world of precision medicine. In the present review, we will discuss the future epidemiology and costs of osteoporosis, the advances in early and accurate diagnosis of osteoporosis, with a special focus on biomarkers and imaging tools. Then we will examine new and refined fracture risk assessment tools, the role of fracture liaison services, and a future perspective on osteoporosis treatment.