Effect of preoperative combined treatment with alendronate and calcitriol on fixation of hydroxyapatite-coated implants in ovariectomized rats

Treatment Strategies in the Osteoporotic Spine

This article reviews the appropriate assessment and management of osteoporotic compression fractures and discusses the implications of osteoporosis on initial patient evaluation, medical optimization for surgery, selection of instrumentation, and surgical technique. Adverse outcomes associated with osteoporosis are discussed. Failure to appropriately evaluate, optimize, and treat spine patients with osteoporotic bone can lead to disastrous complications. Weakened bone can lead to implant failure through cage subsidence and screw pullout, as well as, peri-implant fractures, failure of deformity correction, and proximal kyphosis. These risks must be taken into account when considering operative interventions in these patients.

Impact of Vitamin D on Osseointegration in Dental Implants: A Systematic Review of Human Studies

This systematic review evaluates the impact of Vitamin D levels on dental implant osseointegration, hypothesizing that optimal Vitamin D enhances success rates, and aims to synthesize data on its relationship with clinical outcomes in implantology. A comprehensive search across PubMed, Cochrane Library, and Web of Science databases included seven peer-reviewed articles meeting the criteria for the review. These studies, conducted between 2008 and 2021, included human subjects and explicitly correlated serum Vitamin D levels with dental implant outcomes, following PRISMA guidelines. The selected studies involved 1462 participants and examined 4450 dental implants. Key findings included a varied implant loss rate ranging from 3.9% to 11.4% across the studies. One study reported a 9.8% implant loss rate, yet found no significant association between Vitamin D receptor polymorphism and implant success. Another study indicated successful implantation following Vitamin D3 supplementation, even in severe deficiency cases. The highest implant loss rate (11.1%) was observed in severely Vitamin D-deficient patients, particularly when compounded by risk factors such as smoking and periodontal disease. Additionally, one study noted significantly improved bone density following post-surgical Vitamin D supplementation for up to 12 weeks. The review supports a link between sufficient Vitamin D levels and successful dental implant osseointegration, suggesting Vitamin D deficiency as a potential risk factor for increased failure and advocating for Vitamin D evaluations in pre-surgical planning to potentially enhance implantology outcomes.

Efficacy of the systemic co-administration of vitamin D3 in reversing the inhibitory effects of sodium alendronate on orthodontic tooth movement: A preliminary experimental animal study

INTRODUCTION

Bisphosphonates can severely slow down orthodontic tooth movement (OTM) by reducing bone turnover. This calls for materials and methods to reverse or neutralize their effects on OTM. We propose systemic vitamin D3 (D3) for this purpose.

METHODS

Thirty-two male Wistar rats were randomized into 4 groups of 8 each. Three groups were administered D3 (3 systemic doses of 24,000 IU/kg each), alendronate (ALN) (5 doses of 7 mg/kg each), and ALN+D3 (same doses as mentioned above). One group served as the negative control. The incisors were distalized at 30 g of force for 2 weeks. OTMs were measured blindly. Radicular pressure areas were searched histologically (blindly) for capillaries, Howship's lacunae, osteoclasts, and osteoblasts. Data were analyzed statistically (α = 0.05, α = 0.0083, β <0.1).

RESULTS

OTMs in the groups D3, ALN+D3, ALN, and control were 1.900 ± 0.237, 1.629 ± 0.219, 0.975 ± 0.145, and 1.565 ± 0.324 mm (analysis of variance, P <0.001), respectively. OTM in the ALN group was smaller than all other groups (Tukey, P <0.001). OTM in the D3 group was greater than in the control group (P = 0.054). The ALN+D3 group had greater OTM than the ALN group (P <0.001) but was not significantly different from the D3 (P = 0.153) or control (P = 0.951) groups. All histologic variables were significantly different across groups (Kruskal-Wallis, P <0.001). All the markers in the D3 group were more frequent than those of the other groups (Mann-Whitney U, P <0.001). There were fewer markers in the ALN group than in the control group (P ≤0.001). The ALN+D3 group had more markers than the ALN group in terms of capillaries, osteoclasts, and osteoblasts (P ≤0.007). The ALN+D3 group was similar to the control group regarding capillaries, osteoclasts, and osteoblasts (P ≥0.382).

CONCLUSIONS

Systemic vitamin D3 may accelerate OTM and increase histologic biomarkers of bone turnover. ALN reduces OTM and its histologic biomarkers. Systemic vitamin D3 can reverse this inhibitory effect of ALN on OTM back to normal.

Does vitamin D have an effect on osseointegration of dental implants? A systematic review

Purpose

The aim of this study was to systematically review the available evidence to evaluate the efficacy of vitamin D supplementation or vitamin D depletion on the osseointegration of implants in animals and humans.

Methods

The focus questions addressed were “Do vitamin D deficient subjects treated with (dental) implants have an inferior osseointegration than subjects with adequate serum vitamin D level?” and “Do vitamin D supplemented subjects treated with (dental) implants have a superior osseointegration than subjects with adequate serum vitamin D level?” Humans and animals were considered as subjects in this study. Databases were searched from 1969 up to and including March 2021 using different combination of the following terms: “implant”, “bone to implant contact”, “vitamin D” and “osseointegration”. Letters to the editor, historic reviews, commentaries and articles published in languages other than English and German were excluded. The pattern of the present systematic review was customize to primarily summarize the pertinent data.

Results

Thirteen experimental studies with animals as subject, two clinical studies and three case reports, with humans as subjects, were included. The amount of inserted titanium implants ranged between 24 and 1740. Results from three animal studies showed that vitamin D deficiency has a negative effect on new bone formation and/or bone to implant contact (BIC). Eight animal studies showed that vitamin D supplementation has a enhancing effect on BIC and/or new bone formation around implants. Furthermore, enhancing the impact of vitamin D supplementation on the osseointegration of implants in subjects with diabetes mellitus, osteoporosis and chronic kidney disease (CKD) were assessed. Studies and case reports involving human subjects showed that patients with a low serum vitamin D level have a higher tendency to exhibit an early dental implant failure. When supplemented with vitamin D the osseointegration was successful in the case reports and a beneficial impact on the changes in the bone level during the osseointegration were determined.

Conclusions

Vitamin D deficiency seems to have a negative effect on the osseointegration of implants in animals. The supplementation of vitamin D appears to improve the osseointegration in animals with systemic diseases, such as vitamin D deficiency, diabetes mellitus, osteoporosis, and CKD. Slight evidence supports the hypothesis that humans similarly benefit from vitamin D supplementation in terms of osseointegration. Further investigation is required to maintain these assumptions.

The Impact of Nandrolone Decanoate in the Osseointegration of Dental Implants in a Rabbit Model: Histological and Micro-Radiographic Results

Despite high rates of osseointegration in healthy patients, complex cases present an increased risk of osseointegration failure when treated with dental implants. Furthermore, if immediate loading of the implants is used, maximizing the response of the host organism would be desirable. Anabolic steroids, such as Nandrolone Decanoate (ND), are reported to have beneficial clinical effects on various bone issues such as osteoporosis and bone fractures. However, their beneficial effects in promoting osseointegration in dental implant placement have not been documented. The study aimed to examine histological changes induced by ND in experimental dental implants in rabbit models. Two dental implants were placed in the tibias of 24 adult rabbits. Rabbits were allocated to one of two groups: control group or test group. Rabbits in the latter group were given nandrolone decanoate (15 mg/kg, immediately after implant placement and after 1 week). Micro-radiographic and histological analyses were assessed to characterize the morphological changes promoted by the nandrolone decanoate use. Total bone volume and fluorescence were significantly higher in the control group after 2 weeks. Such a difference between the two groups might indicate that, initially, nandrolone lengthens the non-specific healing period characteristic of all bone surgeries. However, after the beginning of the reparative processes, the quantity of newly formed bone appears to be significantly higher, indicating a positive stimulation of the androgen molecule on bone metabolism. Based on micro-radiology and fluorescence microscopy, nandrolone decanoate influenced bone regeneration in the implant site. The anabolic steroid nandrolone decanoate affects the healing processes of the peri-implant bone and therefore has the potential to improve the outcomes of implant treatment in medically complex patients.

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.

[Overview of animal researches about the effects of systemic drugs on implant osseointegration]

Implant osseointegration is an important biological basis for dental implantology. Many factors, including surgical factors, implant factors, and patients' own factors, affect implant osseointegration. Notably, the application of systemic drugs to improve implant osseointegration has become a research hotspot. This article reviews the effects of systemic drugs on implant osseointegration based on animal researches to provide systemic drug selection to improve implant osseointegration and lay a good foundation for later clinical trials.

Ibandronate Treatment Before and After Implant Insertion Impairs Osseointegration in Aged Rats with Ovariectomy Induced Osteoporosis

Excessive decreases in bone volume (BV) and bone mineral density (BMD) can lead to osteoporosis, potentially hindering implant osseointegration. Bisphosphonates are commonly used to combat osteoporosis by slowing osteoclast-mediated resorption; however, functional osteoclasts are integral to bone remodeling and, thus, implant osseointegration, potentially contraindicating bisphosphonate use during implantation. To optimize the use of implant technologies in patients with compromised bone structure and metabolism, we need a more complete understanding of the biological response to surface design. The goal of this study was to assess the effects of osteoporosis and bisphosphonates on osseointegration of titanium (Ti) implants with microstructured surfaces, which have been shown to support osteoblast differentiation in vitro and rapid osseointegration in vivo. Forty, 8-month-old, virgin, female CD Sprague Dawley rats underwent ovariectomy (OVX) or sham (SHOVX) surgery. After 5 weeks, animals were injected subcutaneously with either the bisphosphonate (BIS), Ibandronate (25 µg/kg), or phosphate-buffered saline (PBS) every 25 days. 1 week after the initial injection, Ø2.5mm × 3.5mm microrough (SLA; grit-blasted/acid etched) implants were placed transcortically in the distal metaphysis of each femur resulting in four groups: 1) SHOVX+PBS; 2) SHOVX+BIS; 3) OVX+PBS; and 4) OVX+BIS. After 28d, qualitative properties of the bone and implant osseointegration were assessed using micro-computed tomography (microCT), calcified histomorphometry (Van Gieson's stain), and removal torque testing. microCT revealed decreased bone volume in OVX rats, which was slowed by bisphosphonate treatment. Reduced bone-to-implant contact (BIC) was evident in OVX+PBS compared to SHOVX+PBS. Although BV/TV was increased in OVX+BIS compared to OVX+PBS, bisphosphonate treatment had no effect on BIC. Removal torque testing revealed a higher maximum torque, torsional stiffness, and torsional energy in SHOVX compared to OVX with no effects due to bisphosphonate treatment. Our results show that osseointegration is decreased in osteoporotic animals. Ibandronate halts the progression of osteoporosis but does not enhance osseointegration. © 2019 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

The effect of alendronate sodium on trabecular bone structure in an osteoporotic rat model

Objectives

TObjectives: This study aims to investigate the effect of alendronate sodium on trabecular bone structure in an osteoporotic rat model.

Materials and methods

Between May 2006 and July 2006, 60 female Wistar Albino rats aged three months were randomly allocated to three groups: sham operated receiving no treatment (Shm); ovariectomized-alendronate receiving 1 mg/kg/day alendronate sodium (Ovx-A), and ovariectomized-vehicle receiving 1 mL/kg/day physiological saline (Ovx-PS). Both Ovx groups received treatment through gastric gavage for 56 days.

Results

Densitometric measurements showed that bone mineral density decreased in the Ovx-PS and increased in Ovx-A groups (p<0.05). Biomechanical measurements showed a decrease in the breaking force in the Ovx-PS group and an increase in the Ovx-A group (p<0.05). Histomorphometric measurements showed that the Shm group had normal trabecular structure, while the Ovx-PS group had a less well- formed trabecular structure with a loss in the trabecular number and thickness and a corresponding increase in the trabecular spacing (p<0.05). In the Ovx-A group, there was an improvement in the trabecular structure with an increase in the trabecular number and thickness and a loss in the trabecular space (p<0.05).

Conclusion

Our study results suggest that alendronate sodium is a valuable treatment agent for osteoporosis in postmenopausal women.

Systemic drugs that influence titanium implant osseointegration

Titanium implants are widely used on an increasing number of patients in orthopedic and dental medicine. Despite the good survival rates of these implants, failures that lead to important socio-economic consequences still exist. Recently, research aimed at improving implant fixation, a process called osseointegration, has focused on a new, innovative field: systemic delivery of drugs. Following implant fixation, patients receive systemic drugs that could either impair or enhance osseointegration; these drugs include anabolic and anti-catabolic bone-acting agents in addition to new treatments. Anabolic bone-acting agents include parathyroid hormone (PTH) peptides, simvastatin, prostaglandin EP4 receptor antagonist, vitamin D and strontium ranelate; anti-catabolic bone-acting agents include compounds like calcitonin, biphosphonates, RANK/RANKL/OPG system and selective estrogen receptor modulators (SERM). Examples of the new therapies include DKK1- and anti-sclerostin antibodies. All classes of treatments have proven to possess positive impacts such as an increase in bone mineral density and on osseointegration. In order to prevent complications from occurring after surgery, some post-operative systemic drugs are administered; these can show an impairment in the osseointegration process. These include nonsteroidal anti-inflammatory drugs, proton pump inhibitors and selective serotonin reuptake inhibitors. The effects of aspirin, acetaminophen, opioids, adjuvants, anticoagulants and antibiotics in implant fixations are not fully understood, but studies are being carried out to investigate potential ramifications. It is currently accepted that systemic pharmacological agents can either enhance or impair implant osseointegration; therefore, proper drug selection is essential. This review aims to discuss the varying effects of three different classes of treatments on improving this process.

Sclerostin antibody treatment improves implant fixation in a model of severe osteoporosis

BACKGROUND

The mechanical fixation of orthopaedic and dental implants is compromised by diminished bone volume, such as with osteoporosis. Systemic administration of sclerostin antibody (Scl-Ab) has been shown to enhance implant fixation in normal animals. In the present study, we tested whether Scl-Ab can improve implant fixation in established osteoporosis in a rat model.

METHODS

We used an ovariectomized (ovx) rat model, in which we found a 78% decrease in trabecular bone volume at the time of implant surgery; sham-ovx, age-matched rats were used as controls. After placement of a titanium implant in the medullary cavity of the distal aspect of the femur, the rats were maintained for four, eight, or twelve weeks and treated biweekly with Scl-Ab or with the delivery vehicle alone. Outcomes were measured with use of microcomputed tomography, mechanical testing, and static and dynamic histomorphometry.

RESULTS

Scl-Ab treatment doubled implant fixation strength in both the sham-ovx and ovx groups, although the enhancement was delayed in the ovx group. Scl-Ab treatment also enhanced bone-implant contact; increased peri-implant trabecular thickness and volume; and increased cortical thickness. These structural changes were associated with an approximately five to sevenfold increase in the bone-formation rate and a >50% depression in the eroded surface following Scl-Ab treatment. Trabecular bone thickness and bone-implant contact accounted for two-thirds of the variance in fixation strength.

CONCLUSIONS

In this model of severe osteoporosis, Scl-Ab treatment enhanced implant fixation by stimulating bone formation and suppressing bone resorption, leading to enhanced bone-implant contact and improved trabecular bone volume and architecture.

CLINICAL RELEVANCE

Systemic administration of anti-sclerostin antibodies might be a useful strategy in total joint replacement when bone mass is deficient.

Perioperative alendronate, risedronate, calcitonin and indomethacin treatment alters femoral stem fixation and periprosthetic bone mineral density in ovariectomized rats

BACKGROUND

Many factors affect implant stability and periprosthetic bone mineral density (BMD) following total joint arthroplasty. We asked whether perioperative alendronate, risedronate, calcitonin and indomethacine administration altered (1) femoral stem shear strength and periprosthetic bone mineral density BMD in ovariectomized rats and (2) whether there were differences in the effect of these drugs.

METHODS

Thirty overiectomized rats were divided into five groups and implanted with intramedullary mini-cortical screws in the femur. Four groups were treated with alendronate, risedronate, salmon calcitonin and indomethacin for 4 weeks preoperatively and 8 weeks postoperatively.

RESULTS

Although alendronate and risedronate increased the periprosthetic BMD more than calcitonin, they did not alter implant fixation compared to calcitonin. Indomethacin significantly decreased the BMD around the stem and implant stability compared to all other groups.

CONCLUSIONS

This study showed that perioperative treatment with bisphosphonates and calcitonin improved the BMD around the stems and implant stability. Although bisphosphonates increased the BMD more than calcitonin, there was no difference in implant stability. Indomethacin markedly decreased the periprosthetic BMD and implant stability. The main clinical significance of our study was the finding about the need to strictly avoid long-term use of high-dose nonsteroidal antiinflammatory drugs for patients who have major joint arthritis and a previous history of arthroplasty.

Efficacy of systemic bisphosphonate delivery on osseointegration of implants under osteoporotic conditions: lessons from animal studies

BACKGROUND

The aim was to systematically review the role of systemic bisphosphonate (BP) delivery on osseointegration of implants under osteoporotic conditions.

METHODS

The addressed focused question was "Does systemic BP delivery enhance osseointegration of implants under osteoporotic conditions?" PubMed/MEDLINE and Google-Scholar databases were searched from 1994 up to and including December 2013 using different combinations of the following keywords: "bone to implant contact", "implant", "bisphosphonate", "osseointegration" and "osteoporosis". Review articles, case-reports, commentaries, letters to the Editor, unpublished articles and articles published in languages other than English were excluded.

RESULTS

Fifteen animal studies fulfilled our eligibility criteria. Osteoporotic conditions were induced via bilateral ovariectomy (OVX). BPs used in the studies were ibandronate, zoledronic acid and alendronate. Results from 12 studies showed that systemic BP delivery significantly increased bone volume and bone-to-implant contact under osteoporotic conditions. Two studies reported no significant difference in osseointegration among OVX animals with and without systemic BP delivery. In one study, systemic BP delivery negatively influenced implant osseointegration. Rough-surfaced and polished implants were used in 11 and one study respectively. In 3 studies implant surface characteristics remained unclear.

CONCLUSION

Within the limits of the present study, it is concluded that systemic BP delivery enhances implant osseointegration in animals with induced osteoporotic conditions. However, in a clinical scenario, the potential risk of BP related ONJ in osteoporotic patients undergoing dental implant therapy cannot be disregarded.

Effect of systemic administered zoledronic acid on osseointegration of a titanium implant in ovariectomized rats

OBJECTIVE

The aim of this study was to evaluate whether zoledronic acid improves post-implant osseointegration in an ovariectomized rat model.

MATERIALS AND METHODS

A total of 36 female Wistar rats were subdivided into three groups: control (CTRL), ovariectomized (OVX) and ovariectomized + zoledronic acid (OVX/ZOL). Both OVX and OVX/ZOL groups underwent ovariectomy procedures, while the CTRL group received a sham operation. After a 90-day waiting period following surgery, the OVX/ZOL group received a weekly intravenous injection of 0.04 mg/kg zoledronic acid over a period of 6 weeks. The CTRL and OVX groups received intravenous injections of 0.9% NaCl, and the injections were administered with a dosing schedule that was identical to that of the OVX/ZOL group. After completing the 6-week injection regimen, every group received a titanium implant that was 1.6 mm in diameter by 4 mm in length, which was placed in the proximal metaphysis of the left tibia. All of the rats were sacrificed after 60 days and the tibia bones were harvested and processed for histological evaluation.

RESULTS

The percentage of bone-implant contact (BIC) varied significantly between groups. Histomorphometric analysis demonstrated that BIC was significantly higher in the OVX/ZOL group than in the OVX group.

CONCLUSIONS

Systemic zoledronic acid improved tibial titanium implant osseointegration in an oestrogen-deficient rat model.

Bone regeneration related to calcium phosphate-coated implants in osteoporotic animal models: a meta-analysis

BACKGROUND

Osteoporosis is a frequent human metabolic bone disorder. Prospectively, global ageing of populations will lead to a major increase of subjects being diagnosed with osteoporosis and in need for dental rehabilitation. However, as local osteoporosis of the jaws affects bone quantity and quality of edentulous regions, osseointegration of dental implants might be hampered. Consequently, calcium phosphate ceramic-coated implants have been suggested to compensate for low bone quantity/density and for impaired bone healing in osteoporosis. Nonetheless, up to now no meta-analytical assessment of the relevant preclinical literature to quantify such a possible positive effect has been undertaken.

MATERIALS AND METHODS

PubMed search, limited to animal models, to identify a possible positive effect of calcium phosphate-coated implants on bone regeneration, was carried out. Further, the reference lists of related review articles and publications selected for inclusion in this review were systematically screened. The primary outcome variables were bone-to-implant contact percentage as assessed histomorphometrically and mechanical stability testing.

RESULTS

The electronic search in the database of the National Library of Medicine resulted in the identification of 2704 titles. These titles were initially screened by the two independent reviewers for possible inclusion, resulting in further consideration of 51 publications. Screening the abstracts led to 22 full-text articles. From these articles, 16 reports were excluded. Finally, six of these original research reports could be selected for evaluation. Additionally, eight publications were identified by manual search. Thus, a total of 14 articles were included for analysis.

CONCLUSIONS

It was concluded that (1) in osteoporotic animal models calcium phosphate ceramic-coated implants are associated with improved bone-to-implant healing as compared to noncoated implants. Moreover, (2) essentially due to quality characteristics of the analyzed original research articles a negative impact of osteoporosis on bone-to-implant healing could not be confirmed. Besides, (3) the established positive bone-to-implant healing effect of calcium phosphate ceramic coatings does not differ between osteoporotic and nonosteoporotic, healthy animal models.

Strategies of spinal fusion on osteoporotic spine

The prevalence of osteoporosis has been increasing globally. Recently surgical indications for elderly patients with osteoporosis have been increasing. However, only few strategies are available for osteoporotic patients who need spinal fusion. Osteoporosis is a result of negative bone remodeling from enhanced function of the osteoclasts. Because bone formation is the result of coupling between osteoblasts and osteoclasts, anti-resorptive agents that induce osteoclast apoptosis may not be effective in spinal fusion surgery, necessitating new bone formation. Therefore, anabolic agents may be more suitable for osteoporotic patients who undergo spinal fusion surgery. The instrumentations and techniques with increased pullout strength may increase fusion rate through rigid fixation. Studies on new osteoinductive materials, methods to increase osteogenic cells, strengthened and biocompatible osteoconductive scaffolds are necessary to enable osteoporotic patients to undergo spinal fusion. When osteoporotic patients undergo spinal fusion, surgeons should consider appropriate osteoporosis medication, instrumentation and technique.

Intermittent weekly administration of human parathyroid hormone (1-34) improves bone-hydroxyapatite block bonding in ovariectomized rats

Hydroxyapatite (HA) blocks have been widely used for the reconstruction of bone defects and as a bone substitute. Bone-implant bonding depends on both implant-related factors and patient variables. Intermittent human parathyroid hormone (h-PTH) has a strong anabolic effect on bone formation. The purpose of the present study is to evaluate whether intermittent h-PTH administration enhances bone-HA block bonding in normal versus ovariectomized (OVX) rats. Cancellous bone osteotomy and HA-block implantation were performed on the proximal left tibia in both OVX and sham-operated 7-month-old female Sprague-Dawley rats. Newly formed cancellous bone around the HA block and bone-HA block bonding were evaluated by bone histomorphometry at 8 weeks after the administration of h-PTH (100 μg/kg/week) or its vehicle. The administration of h-PTH significantly increased cancellous bone volume by stimulating bone formation in OVX rats (p < 0.01). Although bone-HA block bonding was significantly decreased in OVX rats compared to that of sham-operated rats (p < 0.01), h-PTH improved the bone-HA block bonding in OVX rats (p < 0.01). These results suggest that intermittent h-PTH treatment may improve bone-HA bonding in osteoporosis by restoring cancellous bone volume and enhancing cancellous bone formation around the HA block.

Vitamin D deficiency in patients with osteoarthritis undergoing total hip replacement: a cause for concern?

We measured the plasma 25-hydroxyvitamin D(3) (25(OH)D(3)) levels in 62 consecutive Caucasian patients undergoing total hip replacement for osteoarthritis. The patients were divided into two groups based on whether they were vitamin D sufficient or deficient. The groups were matched for age, gender and the American Society of Anaesthesiologists (ASA) grade. The prevalence of vitamin D deficiency in our patients was comparable with recent population-based studies performed in the United Kingdom. Patients with vitamin D deficiency had lower pre-operative Harris hip scores (Mann-Whitney test, p = 0.018) and were significantly less likely to attain an excellent outcome from total hip replacement (chi-squared test, p = 0.038). Vitamin D levels were found to positively correlate with both pre- and post-operative Harris hip scores. These results warrant further study of vitamin D deficiency in patients undergoing joint replacement as it is a risk factor for a suboptimal outcome which is relatively simple and cheap to correct.

Differences between bisphosphonates in binding affinities for hydroxyapatite

Bisphosphonates (BPs) inhibit bone resorption and are widely used for the treatment of bone diseases, including osteoporosis. BPs are also being studied for their effects on hydroxyapatite (HAP)-containing biomaterials. There is a growing appreciation that there are hitherto unexpected differences among BPs in their mineral binding affinities that affect their pharmacological and biological properties. To study these differences, we have developed a method based on fast performance liquid chromatography using columns of HAP to which BPs and other phosphate-containing compounds can adsorb and be eluted by using phosphate buffer gradients at pH 6.8. The individual compounds emerge as discrete and reproducible peaks for a range of compounds with different affinities. For example, the peak retention times (min; mean +/- SEM) were 22.0 +/- 0.3 for zoledronate, 16.16 +/- 0.44 for risedronate, and 9.0 +/- 0.28 for its phosphonocarboxylate analog, NE10790. These results suggest that there are substantial differences among BPs in their binding to HAP. These differences may be exploited in the development of biomaterials and may also partly explain the extent of their relative skeletal retention and persistence of biological effects observed in both animal and clinical studies.

Alternative indications for bisphosphonate therapy

Bisphosphonates are currently used in the treatment of osteoporosis (postmenopausal and steroid-induced), hypercalcemia of malignancy, Paget's disease of bone, multiple myeloma, and skeletally related events associated with metastatic bone disease in breast, prostate, lung, and other cancers. There are, however, numerous other conditions where a decrease in bone remodeling by bisphosphonates might aid in disease management. The focus of this review will be to discuss a select group of conditions for which bisphosphonate therapy may be efficacious. In this review we present several cases where bisphosphonates have been used as a primary or adjunctive treatment for giant cell lesions of the jaws. Use of bisphosphonate therapy for giant cell tumors of the appendicular skeleton, pediatric osteogenesis imperfecta, fibrous dysplasia, Gaucher's disease, and osteomyelitis will be discussed. Finally, we will review previous in vivo studies on the use of bisphosphonates to augment integration and to treat osteolysis surrounding failing orthopedic implants.

Effect of combined local treatment with zoledronic acid and basic fibroblast growth factor on implant fixation in ovariectomized rats

Osteoporosis is a skeletal disorder characterized by low bone mass and deterioration of bone microarchitecture resulting in bone fragility, which impairs fixation of the implants. Zoledronic acid (ZOL) is a potential inhibitor of osteoclast-mediated bone resorption and basic fibroblast growth factor (bFGF) is a growth factor that stimulates osteoblast-mediated bone formation, and these drugs could enhance fixation of implants under osteoporotic conditions. In this study, 40 ovariectomized (OVX) rats were randomly divided into 4 groups (n=10 for each group) and underwent bilateral tibiae implantation using hydroxyapatite (HA)-coated titanium implant: Control group (distilled water immersing before implantation), ZOL group (1 mg/ml of ZOL immersing), bFGF group (20 microg/ml of bFGF immersing), and ZOL+bFGF group (1 mg/ml of ZOL and 20 microg/ml of bFGF immersing). At 3 months after implantation, all animal were sacrificed and the tibiae were harvested for histology, micro-CT examinations and biomechanical testing. Bone area and contact, determined by histomorphometric analysis, were 2.7-fold and 1.8-fold in the ZOL-treated implants, 1.9-fold and 1.8-fold in the bFGF-treated implants, 3.6-fold and 2.3-fold in the both-treated implants compared with controls (p<0.01). Such significant effects were further confirmed by microstructure parameters, the bone volume ratio and the percentage osteointegration were significantly increased by ZOL treatment (3.0-fold and 1.8-fold), bFGF treatment (1.2-fold and 1.9-fold) and ZOL+bFGF treatment (3.3-fold and 2.7-fold) (p<0.001). In addition, push-out test showed that the maximum force and the corresponding interfacial shear strength of the implants treated by ZOL, bFGF and ZOL+bFGF was 8.4-fold and 8.6-fold, 3.8-fold and 3.7-fold, 10.8-fold and 10.7-fold of the control levels, respectively (p<0.05). The combined treatment was better than either treatment alone for force, but was not different from ZOL alone for interfacial strength. The significant correlation between biomechanical and micro-CT parameters demonstrates the role of microstructure assessments in predicting mechanical fixation of implants (p<0.01). Our study suggests that locally applied ZOL or bFGF may improve implant fixation in the ovariectomized rats, and that combined treatment has more beneficial effects on osseointegration, peri-implant bone formation and maximum force than either intervention alone.