Clinical evaluation of medicinal products for acceleration of fracture healing in patients with osteoporosis

A Retrospective Short-Term Evaluation Using a Polyaxial Plating System in 60 Small Animal Fractures

OBJECTIVE

 The aim of this study was to retrospectively evaluate the use, complications and outcomes of the Liberty Lock System (LLS) used to repair fractures in dogs and cats.

STUDY DESIGN

 Medical records (October 2016-June 2019) of dog and cat fractures repaired with the LLS were reviewed. Data reviewed included signalment, fracture classification, complications and radiographic outcome.

RESULTS

 The LLS was used to repair 60 fractures (57 appendicular and 3 axial) in 54 dogs and 6 cats. Mean time to radiographic union was 6 weeks (range: 4-16). Radiographic union was achieved in all 60 fractures with 55/60 healing without recorded complications. Major complications 4/60 and minor complication 1/60 rates were low and no catastrophic complications occurred. The most common major complication was surgical site infection.

CONCLUSION

 The LLS allowed for successful repair in all 60 cases with a wide variety of fractures. The LLS had a similar complication rate and time to radiographic union to that reported in other veterinary locking plate systems. The LLS is a reliable locking plate system which offers some advantages such as a low-profile plate with the ability to place non-polyaxial to angled polyaxial screws, to treat fractures in dogs and cats.

Application of BMP in Bone Tissue Engineering

At present, bone nonunion and delayed union are still difficult problems in orthopaedics. Since the discovery of bone morphogenetic protein (BMP), it has been widely used in various studies due to its powerful role in promoting osteogenesis and chondrogenesis. Current results show that BMPs can promote healing of bone defects and reduce the occurrence of complications. However, the mechanism of BMP in vivo still needs to be explored, and application of BMP alone to a bone defect site cannot achieve good therapeutic effects. It is particularly important to modify implants to carry BMP to achieve slow and sustained release effects by taking advantage of the nature of the implant. This review aims to explain the mechanism of BMP action in vivo, its biological function, and how BMP can be applied to orthopaedic implants to effectively stimulate bone healing in the long term. Notably, implantation of a system that allows sustained release of BMP can provide an effective method to treat bone nonunion and delayed bone healing in the clinic.

Comparison between real-world practice and application of the FRAX algorithm in the treatment of osteoporosis

BACKGROUND AND AIMS

The most recent guidelines suggest treating patients whose FRAX 10-year fracture risk scores are ≥ 20%. However, this method of evaluation does not take into account parameters that are nonetheless relevant to the therapeutic choice. Our aim was to compare the therapeutic choices for treatment based on a wider assessment (real-world practice) with those based on FRAX scores, taking 20% as the cut-off score.

METHODS

We obtained the medical history, bone mineral density (BMD) values, and the presence of major fragility fractures in a sample of 856 postmenopausal women. The 10-year FRAX risk of major osteoporotic fracture was calculated, and patients were grouped into risk classes ("FRAX < 20%" = low, "FRAX ≥ 20%" = high); we then compared the treated and untreated patients in each class. After an average interval of 2.5 years, changes in lumbar and femoral BMD and appearances of new fragility fractures were recorded.

RESULTS

83% of high-risk patients and 57% of low-risk patients were treated. The therapeutic decision was based mainly on densitometric values and the presence of vertebral fractures. At the 2.5 year follow-up, lumbar spine and femur BMD had decreased in the untreated group; 9.9% of the treated patients developed new vertebral fragility fractures, compared with 5.3% of the untreated patients.

DISCUSSION AND CONCLUSIONS

Our wider assessment designated as at high fracture risk a group of patients who had not been identified by the FRAX assessment. FRAX could underestimate the risk of fracture in older people, for which the therapeutic choice should consider a broader approach, also based on individual patient's needs.

Confirmation of Calcium Phosphate Cement Biodegradation after Jawbone Augmentation around Dental Implants Using Three-Dimensional Visualization and Segmentation Software

The use of autologous bone graft for oral rehabilitation of bone atrophy is considered the gold standard. However, the available grafts do not allow a fast loading of dental implants, as they require a long healing time before full functionality. Innovative bioactive materials provide an easy-to-use solution to this problem. The current study shows the feasibility of calcium phosphate cement paste (Paste-CPC) in the sinus. Long implants were placed simultaneously with the cement paste, and provisional prosthetics were also mounted in the same sessions. Final prosthetics and the full loading took place within the same week. Furthermore, the study shows for the first time the possibility to monitor not only healing progression using Cone Beam Computer tomography (CBCT) but also material retention, over two years, on a case study example. The segmented images showed a 30% reduction of the cement size and an increased mineralized tissue in the sinus. Mechanical testing was performed qualitatively using reverse torque after insertion and cement solidification to indicate clinical feasibility. Both functional and esthetic satisfaction remain unchanged after one year. This flowable paste encourages the augmentation procedure with less invasive measure through socket of removed implants. However, this limitation can be addressed in future studies.

Overview of Skeletal Repair (Fracture Healing and Its Assessment)

The study of postnatal skeletal repair is of immense clinical interest. Optimal repair of skeletal tissue is necessary in all varieties of elective and reparative orthopedic surgical treatments. However, the repair of fractures is unique in this context in that fractures are one of the most common traumas that humans experience and are the end-point manifestation of osteoporosis, the most common chronic disease of aging. In the first part of this introduction the basic biology of fracture healing is presented. The second part discusses the primary methodological approaches that are used to examine repair of skeletal hard tissue and specific considerations for choosing among and implementing these approaches.

Systematic review assessing the evidence for the use of stem cells in fracture healing

AIMS

Bone demonstrates good healing capacity, with a variety of strategies being utilized to enhance this healing. One potential strategy that has been suggested is the use of stem cells to accelerate healing.

METHODS

The following databases were searched: MEDLINE, CENTRAL, EMBASE, Cochrane Database of Systematic Reviews, WHO-ICTRP, ClinicalTrials.gov, as well as reference checking of included studies. The inclusion criteria for the study were: population (any adults who have sustained a fracture, not including those with pre-existing bone defects); intervention (use of stem cells from any source in the fracture site by any mechanism); and control (fracture healing without the use of stem cells). Studies without a comparator were also included. The outcome was any reported outcomes. The study design was randomized controlled trials, non-randomized or observational studies, and case series.

RESULTS

In all, 94 eligible studies were identified. The clinical and methodological aspects of the studies were too heterogeneous for a meta-analysis to be undertaken. A narrative synthesis examined study characteristics, stem cell methods (source, aspiration, concentration, and application) and outcomes.

CONCLUSION

Insufficient high-quality evidence is available to determine the efficacy of stem cells for fracture healing. The studies were heterogeneous in population, methods, and outcomes. Work to address these issues and establish standards for future research should be undertaken.Cite this article: Bone Joint Open 2020;1-10:628-638.

Resveratrol inhibits parathyroid hormone-induced apoptosis in human aortic smooth muscle cells by upregulating sirtuin 1

Background: Cardiovascular disease is the leading cause of death in patients with chronic kidney disease, so there is an urgent need to identify therapeutic targets to control the progression of cardiovascular disease. Apoptosis of aortic smooth muscle cells can promote cardiovascular disease, but the role of parathyroid hormone (PTH) and sirtuin 1 in the pathophysiology of apoptosis is still unclear.

Methods: Cultured human aortic smooth muscle cells (HASMCs) were stimulated with 10^–6, 10^–8, or 10^–10 mol/L PTH for different days, apoptosis was measured by flow cytometry and sirtuin 1 and Bcl-2 protein levels in cell extracts were analyzed by western blotting. HASMCs were stimulated with PTH (10^–8 mol/L) and 50 or 100 μmol/L RES for 3 d, apoptosis was measured by flow cytometry and sirtuin 1 and Bcl-2 protein levels in cell extracts were analyzed by western blotting.

Results: We found that PTH decreased the expression of sirtuin 1 and Bcl-2, inducing apoptosis (p<.05). Resveratrol (RES), a sirtuin 1 agonist, inhibited PTH-induced apoptosis and restored Bcl-2 expression (p<.05).

Conclusions: PTH induces apoptosis in HASMCs. Resveratrol inhibits PTH-induced apoptosis in HASMCs.

Abaloparatide, a PTH receptor agonist with homology to PTHrP, enhances callus bridging and biomechanical properties in rats with femoral fracture

Fractures typically heal via endochondral and intramembranous bone formation, which together form a callus that achieves union and biomechanical recovery. PTHrP, a PTH receptor agonist, plays an important physiological role in fracture healing as an endogenous stimulator of endochondral and intramembranous bone formation. Abaloparatide, a novel systemically-administered osteoanabolic PTH receptor agonist that reduces fracture risk in women with postmenopausal osteoporosis, has 76% homology to PTHrP, suggesting it may have potential to improve fracture healing. To test this hypothesis, ninety-six 12-week-old male rats underwent unilateral internally-stabilized closed mid-diaphyseal femoral fractures and were treated starting the next day with daily s.c. saline (Vehicle) or abaloparatide at 5 or 20 µg/kg/d for 4 or 6 weeks (16 rats/group/time point). Histomorphometry and histology analyses indicated that fracture calluses from the abaloparatide groups exhibited significantly greater total area, higher fluorescence scores indicating more newly-formed bone, and higher fracture bridging scores versus Vehicle controls. Callus bridging score best correlated with callus cartilage score (r = 0.64) and fluorescence score (r = 0.67) at week 4, and callus area correlated with cartilage score (r = 0.60) and fluorescence score (r = 0.89) at Week 6. By micro-CT, calluses from one or both abaloparatide groups had greater bone volume, bone volume fraction, bone mineral content, bone mineral density, and cross-sectional area at both time points versus Vehicle controls. Destructive bending tests indicated greater callus maximum load and stiffness in one or both abaloparatide groups at both time points versus Vehicle controls. These results provide preliminary preclinical evidence for improved fracture healing with systemically-administered abaloparatide. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

An innovative Mg/Ti hybrid fixation system developed for fracture fixation and healing enhancement at load-bearing skeletal site

Magnesium (Mg) is a potential biomaterial suitable for developing biodegradable orthopaedic implants, especially as internal fixators for fracture fixation at non-load bearing skeletal sites. However, Mg alone cannot provide sufficient mechanical support for stable fracture fixation at load bearing sites due to its rapid degradation in the early stage after implantation. In consideration of the strengths and weaknesses of Mg, we developed an innovative magnesium/titanium (Mg/Ti) hybrid fixation system for long bone fracture fixation and investigated the fixation efficacy. The finite element analysis (FEA) results indicated that the Mg/Ti hybrid fixation system provided sufficient mechanical support for fracture fixation at load-bearing skeletal site. As a proof-of-concept, we performed a "Z-shaped" open osteotomy at the mid-shaft of rabbit tibia. For comparison, the animals were divided into two groups: Mg/Ti group (fixated with Mg screws and Ti fixators) and Ti control group (fixated with Ti screws and Ti fixators). The radiographic, four-point bending mechanical test, histological and histomorphometric analysis were postoperatively performed in a temporal manner up to 12 weeks. Both X-ray and micro-CT images of the Mg/Ti group showed a larger callus (14.7% at 3rd week and 24.8% at 6th week, n = 5-7, p < 0.05) in the regions of interest (ROIs) over time, especially at the opposite cortex of the fixation plate. At the 12th week post-operation, the biomechanical test result indicated that the rabbit tibia in the Mg/Ti group healed better and the overall mechanical strength was approximately 3-fold higher (n = 8, p < 0.05) than that at 6th week. Furthermore, the FEA revealed that the Mg/Ti group had a higher mechanical strength (19.5% at week 6 and 31.5% at week 12) at the specified ROI and resulted in an earlier and faster endochondral ossification (68.0% at week 3 and 71.4% at week 6) with a higher expression of osteocalcin (54.0%) and collagen I (34.2%) than the Ti control group (n = 4, p < 0.05). Further evaluation suggested that a higher expression of calcitonin gene-related peptide (CGRP), a known osteogenic neuron peptide, in the fracture callus of the Mg/Ti group might be a major underlying mechanism of enhanced fracture healing attributed to the release of Mg ions during the degradation of Mg screws.

Serum proteomic assessment of the progression of fracture healing

A targeted proteomic analysis of murine serum over a 35-day course of fracture healing was carried out to determine if serum proteomic changes could be used to monitor the biological progression of fracture healing. Transverse, closed femoral fractures where generated and stabilized with intramedullary fixation. A single stranded DNA aptamer-based multiplexed proteomic approach was used to assay 1,310 proteins. The transcriptomic profiles for genes matching the 1,310 proteins were obtained by microarray analysis of callus mRNA. Of the 1,310 proteins analyzed, 850 proteins showed significant differences among the time points (p-value <0.05). Ontology assessment associated these proteins with osteoblasts, monocyte/macrophage lineages, mesenchymal stem cell lines, hepatic tissues, and lymphocytes. Temporal clustering of these data identified proteins associated with inflammation, cartilage formation and bone remodeling stages of healing. VEGF, Wnt, and TGF-βsignaling pathways were restricted to the period of cartilage formation. Comparison of the proteomic and transcriptomic profiles showed that 87.5% of proteins in serum had concordant expression to their mRNA expression in the callus, while 12.5% of the protein and mRNA expression patterns were discordant. The discordant proteins that were elevated in the serum but down regulated in callus mRNA expression were related to clotting functions, allograft rejection, and complement function. While proteins down regulated in the serum and elevated in callus mRNA were associated with osteoblast function, NF-ĸb, and activin signaling. These data show the serum proteome may be used to monitor the different biological stages of fracture healing and have translational potential in assessing human fracture healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1153-1163, 2018.

Optimization of screw fixation in rat bone with extracorporeal shock waves

Screw fixation in osteoporotic patients is becoming an increasing problem in orthopaedic surgery as deterioration of cortical and cancellous bone hamper biomechanical stability and screw fixation. This might result in delayed weight-bearing or failure of instrumentation. We hypothesized that local peri-operative shock wave treatment can optimize osseointegration and subsequent screw fixation. In eight female Wistar rats, two cancellous and two cortical bone screws were implanted in both femora and tibiae. Immediately after implantation, 3.000 unfocused extracorporeal shock waves (energy flux density 0.3 mJ/mm² ) were applied to one side. The other side served as non-treated internal control. Evaluation of osseointegration was performed after 4 weeks with the use of microCT scanning, histology with fluorochrome labeling, and pull-out tests of the screws. Four weeks after extracorporeal shock wave treatment, treated legs exhibited increased bone formation and screw fixation around cortical screws as compared to the control legs. This was corroborated by an increased pull-out of the shock wave treated cortical screws. The cancellous bone screws appeared not to be sensitive for shock wave treatment. Formation of neocortices after shock wave therapy was observed in three of eight animals. Furthermore, de novo bone formation in the bone marrow was observed in some animals. The current study showed bone formation and improved screw fixation as a result of shock wave therapy. New bone was also formed at locations remote from the screws, hence, not contributing to screw fixation. Further, research is warranted to make shock wave therapy tailor-made for fracture fixation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:76-84, 2018.

Conservative Treatment for Minimally Displaced Type B Periprosthetic Femoral Fractures

BACKGROUND

Surgical treatment has been invariably indicated for Vancouver type B periprosthetic femoral fractures (PFFs), which involve femoral diaphysis around stem. We evaluated the outcomes of nonoperative management in patients with minimally displaced type B PFFs around cementless stem.

METHODS

From October 2009 to March 2016, 60 type B PFFs were treated at 1 institution. Among them, 19 minimally (<5 mm) displaced PFFs (31.7%, 19/60), which occurred around cementless stems, were treated nonsurgically with use of teriparatide. There were 6 men and 13 women. The mean age was 77.9 years (range, 51-98 years) at the time of PFF. The femoral stem was stable (type B1) in 11 patients and unstable (type B2) in 8. Teriparatide was injected from 1 to 4 months (mean, 3.2 months). We evaluated time to radiologic union and union rate.

RESULTS

A successful union was obtained in 16 patients (89.5%, 17/19) at 2 to 6 months (mean, 3.5 months). The union rate was 100% (11/11) in type B1 fractures and 75% (6/8) in type B2 fractures.

CONCLUSION

Our study showed that conservative treatment is feasible for the cases of type B1 minimally displaced periprosthetic fractures, and it may also be considered as an alternative option for type B2 minimally displaced periprosthetic fractures.

Injectable hybrid system for strontium local delivery promotes bone regeneration in a rat critical-sized defect model

Strontium (Sr) has been described as having beneficial influence in bone strength and architecture. However, negative systemic effects have been reported on oral administration of Sr ranelate, leading to strict restrictions in clinical application. We hypothesized that local delivery of Sr improves osteogenesis without eliciting detrimental side effects. Therefore, the in vivo response to an injectable Sr-hybrid system composed of RGD-alginate hydrogel cross-linked in situ with Sr and reinforced with Sr-doped hydroxyapatite microspheres, was investigated. The system was injected in a critical-sized bone defect model and compared to a similar Sr-free material. Micro-CT results show a trend towards higher new bone formed in Sr-hybrid group and major histological differences were observed between groups. Higher cell invasion was detected at the center of the defect of Sr-hybrid group after 15 days with earlier bone formation. Higher material degradation with increase of collagen fibers and bone formation in the center of the defect after 60 days was observed as opposed to bone formation restricted to the periphery of the defect in the control. These histological findings support the evidence of an improved response with the Sr enriched material. Importantly, no alterations were observed in the Sr levels in systemic organs or serum.

In vivo and clinical application of strontium-enriched biomaterials for bone regeneration: A systematic review

OBJECTIVES

This systematic review aimed to assess the in vivo and clinical effect of strontium (Sr)-enriched biomaterials in bone formation and/or remodelling.

METHODS

A systematic search was performed in Pubmed, followed by a two-step selection process. We included in vivo original studies on Sr-containing biomaterials used for bone support or regeneration, comparing at least two groups that only differ in Sr addition in the experimental group.

RESULTS

A total of 572 references were retrieved and 27 were included. Animal models were used in 26 articles, and one article described a human study. Osteoporotic models were included in 11 papers. All articles showed similar or increased effect of Sr in bone formation and/or regeneration, in both healthy and osteoporotic models. No study found a decreased effect. Adverse effects were assessed in 17 articles, 13 on local and four on systemic adverse effects. From these, only one reported a systemic impact from Sr addition. Data on gene and/or protein expression were available from seven studies.

CONCLUSIONS

This review showed the safety and effectiveness of Sr-enriched biomaterials for stimulating bone formation and remodelling in animal models. The effect seems to increase over time and is impacted by the concentration used. However, included studies present a wide range of study methods. Future work should focus on consistent models and guidelines when developing a future clinical application of this element.Cite this article: N. Neves, D. Linhares, G. Costa, C. C. Ribeiro, M. A. Barbosa. In vivo and clinical application of strontium-enriched biomaterials for bone regeneration: A systematic review. Bone Joint Res 2017;6:366-375. DOI: 10.1302/2046-3758.66.BJR-2016-0311.R1.

Strontium-Doped Amorphous Calcium Phosphate Porous Microspheres Synthesized through a Microwave-Hydrothermal Method Using Fructose 1,6-Bisphosphate as an Organic Phosphorus Source: Application in Drug Delivery and Enhanced Bone Regeneration

Nanostructured calcium phosphate porous microspheres are of great potential in drug delivery and bone regeneration due to their large specific surface area, biocompatibility, and similarity to inorganic component of osseous tissue. In this work, strontium (Sr)-doped amorphous calcium phosphate porous microspheres (SrAPMs) were synthesized through a microwave-hydrothermal method using fructose 1,6-bisphosphate trisodium salt as the source of phosphate ions. The SrAPMs showed a mesoporous structure and a relatively high specific area. Compared with the hydroxyapatite nanorods prepared by using Na₂HPO₄·12H₂O as the phosphorus source, the SrAPMs with a higher specific surface area were more effective in drug loading using vancomycin as the antiobiotics of choice and consequently having a higher antibacterial efficiency both on agar plates and in broths. Furthermore, to assess the potential application of SrAPMs in bone defect repair, a novel biomimetic bone tissue-engineering scaffold consisting of collagen (Coll) and SrAPMs was constructed using a freeze-drying fabrication process. Incorporation of the SrAPMs not only improved the mechanical properties, but also enhanced the osteogenesis of rat bone marrow mesenchymal stem cells. The in vivo experiments demonstrated that the SrAPMs/Coll scaffolds remarkably enhanced new bone formation compared with the Coll and APMs/Coll scaffolds in a rat critical-sized calvarial defect model at 8 weeks postimplantation. In summary, SrAPMs developed in this work are promising as antibiotic carriers and may encourage bone formation when combined with collagen.

Parathyroid hormone 1-34 and skeletal anabolic action: The use of parathyroid hormone in bone formation

Intermittently administered parathyroid hormone (PTH 1-34) has been shown to promote bone formation in both human and animal studies. The hormone and its analogues stimulate both bone formation and resorption, and as such at low doses are now in clinical use for the treatment of severe osteoporosis. By varying the duration of exposure, parathyroid hormone can modulate genes leading to increased bone formation within a so-called 'anabolic window'. The osteogenic mechanisms involved are multiple, affecting the stimulation of osteoprogenitor cells, osteoblasts, osteocytes and the stem cell niche, and ultimately leading to increased osteoblast activation, reduced osteoblast apoptosis, upregulation of Wnt/β-catenin signalling, increased stem cell mobilisation, and mediation of the RANKL/OPG pathway. Ongoing investigation into their effect on bone formation through 'coupled' and 'uncoupled' mechanisms further underlines the impact of intermittent PTH on both cortical and cancellous bone. Given the principally catabolic actions of continuous PTH, this article reviews the skeletal actions of intermittent PTH 1-34 and the mechanisms underlying its effect.

CITE THIS ARTICLE

L. Osagie-Clouard, A. Sanghani, M. Coathup, T. Briggs, M. Bostrom, G. Blunn. Parathyroid hormone 1-34 and skeletal anabolic action: The use of parathyroid hormone in bone formation. Bone Joint Res 2017;6:14-21. DOI: 10.1302/2046-3758.61.BJR-2016-0085.R1.

Effects of Ovariectomy and Corticosteroid-Induced Osteoporosis on the Osteoinductivity of rhBMP-2 in a Segmental Long-Bone Defect Model

This study used the segmental long-bone defect model to assess the effects of osteoporosis on the formation of new bones and the osteoinductivity of recombinant human bone morphogenetic protein-2 (rhBMP-2). Seventy-two female Sprague-Dawley rats were divided into two groups: an osteoporosis group with ovariectomies and dexamathasone intramuscular injections and a sham group. When they reached 22 weeks in age, each group was further divided into two groups and a 5-mm defect was made in both fibular mid-shafts of each rat. One fibula in each rat was picked randomly and was injected with 0.05 mL of hydrogel carrier; the opposite fibula was injected with the same carrier mixed with rhBMP-2 (10 μg). After rearing for a further 5 and 9 weeks, the ratios of the lengths of the newly formed bones in the fibular defects were determined using micro-CT and undecalcified histology. The sham rhBMP-2-injected group-in all of the 5- and 9-week-kept groups-showed a significantly higher bridging bone formation ratio than the other three groups. The osteoporosis rhBMP-2-injected group showed a significantly higher ratio than both the non-rhBMP-2-injected sham hydrogel and the osteoporosis hydrogel groups. The comparison of the micro-CT parameters of the newly formed bones showed that the sham rhBMP-2 group at both 5 and 9 weeks compared with the osteoporosis rhBMP-2 group had significantly higher percentage bone volumes, trabecular thicknesses, and trabecular numbers, in addition to significantly lower specific surfaces, trabecular pattern factors, and structural model indices. The histology results showed that the sham-rhBMP-2 group began forming bridging bones in the defect areas at 5 weeks, and at 9 weeks, trabeculae and marrow spaces were observed. However, the osteoporosis rhBMP-2 group exhibited a relatively minor level of new bone and trabecula formation. Consequently, the rhBMP-2 group showed significantly increased bone formation in the osteoporosis rat fibular defect model compared with the hydrogel group, whereas the new bone quantities, qualities, and remodeling in the osteoporosis rhBMP-2 group were less effective than those in the sham-rhBMP-2 group, signaling that ovariectomy and corticosteroid-induced osteoporosis significantly undermines rhBMP-2 osteoinductivity.

Treatment study of distal femur for parathyroid hormone (1-34) and β-tricalcium phosphate on bone formation in critical size defects in rats

The objective of this study was to evaluate local bone formation following systemic administration of parathyroid hormone (1-34), a surgically implanted synthetic β-tricalcium phosphate bone biomaterial serving as a matrix to support new bone formation. Twelve weeks after bilateral ovariectomy, all rats underwent bone defect in the distal femurs, and β-tricalcium phosphate was implanted into critical sized defects. After defect operation, all animals were randomly divided into four groups and received following subcutaneous injections until death at four and eight weeks: sham rats (group ST); sham rats + parathyroid hormone, 30 µg/kg, three times a week (group SPT); OVX rats (group OT); and OVX rats + parathyroid hormone (group OPT). The distal femurs of rats were harvested for evaluation. The treatment group demonstrating the highest levels of new bone formation was the defects treated with parathyroid hormone as assessed by micro-computed tomography, biomechanical strength, and histological analysis for sham rats. Furthermore, parathyroid hormone showed a stronger effect on accelerating the degradation of β-tricalcium phosphate. Osteoporosis can limit the function of parathyroid hormone and/or β-tricalcium phosphate. The results from our study demonstrate that combination of parathyroid hormone and β-tricalcium phosphate brings better effect to bone tissue repair in non-osteoporosis and/or osteoporosis status.

Evaluation of the effectiveness of the angular stable locking system in patients with distal tibial fractures treated with intramedullary nailing: a multicenter randomized controlled trial

BACKGROUND

Angular stable locking of intramedullary nails has been shown to enhance fixation stability of tibial fractures in biomechanical and animal studies. The aim of our study was to assess whether use of the angular stable locking system or conventional locking resulted in earlier full weight-bearing with minimum pain for patients with a distal tibial fracture treated with an intramedullary nail.

METHODS

A prospective multicenter, randomized, patient-blinded trial was conducted with adults who had a distal tibial fracture. Patients' fractures were managed with an intramedullary nail locked with either an angular stable locking system or conventional locking screws. Outcomes were evaluated at six weeks, twelve weeks, six months, and one year after surgery. Time to full weight-bearing with minimum pain was calculated with use of daily entries from patient diaries. Secondary outcomes included pain at the fracture site under load, quality of life, gait analysis, mobility, radiographic findings, and adverse events.

RESULTS

One hundred and forty-two patients were randomly allocated to two treatment groups: seventy-five to the group receiving intramedullary nailing with the angular stable locking system and sixty-seven to the group receiving conventional intramedullary nailing. No clinically important differences were found for either the primary or secondary outcome parameters between the groups during the entire follow-up period.

CONCLUSIONS

Use of an angular stable locking system with intramedullary nailing did not improve the outcome compared with conventional locking screws in the treatment of distal tibial fractures.

Application of F-18-sodium fluoride (NaF) dynamic PET-CT (dPET-CT) for defect healing: a comparison of biomaterials in an experimental osteoporotic rat model

BACKGROUND

The aim of the current study was to measure and compare the effect of various biomaterials for the healing of osteoporotic bone defects in the rat femur using 18F-sodium fluoride dPET-CT.

MATERIAL AND METHODS

Osteoporosis was induced by ovariectomy and a calcium-restricted diet. After 3 months, rats were operated on to create a 4-mm wedge-shaped defect in the distal metaphyseal femur. Bone substitution materials of calcium phosphate cement (CPC), composites of collagen and silica, and iron foams with interconnecting pores were inserted. Strontium or bisphosphonate, which are well known for having positive effects in osteoporosis treatment, were added into the materials. Eighteen weeks after osteoporosis induction and 6 weeks following femoral surgery, dPET-CT studies scan were performed with 18F-Sodium Fluoride. Standardized uptake values (SUVs) and a 2-tissue compartmental learning-machine model (K1-k4, vessel density [VB], influx [ki]) were used for quantitative analysis.

RESULTS

k3, reflecting the formation of fluoroapatite, revealed a statistically significant increase at the biomaterial-bone interface due to the Sr release from strontium-modified calcium phosphate cement (SrCPC) compared to CPC, which demonstrated enhanced new bone formation. In addition, k3 as measured in the porous scaffold silica/collagen xerogel (Sc-B30), showed a significant increase based on Wilcoxon rank-sum test (p<0.05) as compared with monolithic silica/collagen xerogel (B30) in the defect region. Furthermore, ki, reflecting the net plasma clearance of tracer to bone mineral measured in the iron foam with coating of the bisphosphonate zoledronic acid (Fe-BP), was enhanced as compared with plain iron foam (Fe) in the defect region.

CONCLUSIONS

k3 was the most significant parameter for the characterization of healing processes and revealed the best differentiation between the 2 different biomaterials. PET scanning using 18F-sodium fluoride seems to be a sensitive and useful method for evaluation of bone healing after replacement with these biomaterials.

Overview of skeletal repair (fracture healing and its assessment)

The study of postnatal skeletal repair is of immense clinical interest. Optimal repair of skeletal tissue is necessary in all varieties of elective and reparative orthopedic surgical treatments. However, the repair of fractures is unique in this context in that fractures are one of the most common traumas that humans experience and are the end-point manifestation of osteoporosis, the most common chronic disease of aging. In the first part of this introduction the basic biology of fracture healing is presented. The second part discusses the primary methodological approaches that are used to examine repair of skeletal hard tissue and specific considerations for choosing among and implementing these approaches.

Patient-important outcome for the assessment of fracture repair

Current evidence indicates that fracture healing assessment is limited to the use of one or two domains (such as pain, range of motion or mobility) in any single study. Functional outcome measures, which include physician-rated or observer-based impairment ratings and patient self-reported or observer-based activity limitation measures, better position the effectiveness of a given intervention towards patient-important outcomes. Health status measures, for example, cover a wide-range of physical, emotional, and social health dimensions. In this paper, we will examine the utility of metrics to assess fracture healing that are important to both the patient and provider, with selected examples from the recent literature. We recommend outcome measures with established and verified reliability and validity. Policy-makers and other stakeholders need to have an accurate assessment of treatment outcome that includes changes in function over time-adequate measures, should be re-applied at periodic intervals.

Podoplanin immunopositive lymphatic vessels at the implant interface in a rat model of osteoporotic fractures

Insertion of bone substitution materials accelerates healing of osteoporotic fractures. Biodegradable materials are preferred for application in osteoporotic patients to avoid a second surgery for implant replacement. Degraded implant fragments are often absorbed by macrophages that are removed from the fracture side via passage through veins or lymphatic vessels. We investigated if lymphatic vessels occur in osteoporotic bone defects and whether they are regulated by the use of different materials. To address this issue osteoporosis was induced in rats using the classical method of bilateral ovariectomy and additional calcium and vitamin deficient diet. In addition, wedge-shaped defects of 3, 4, or 5 mm were generated in the distal metaphyseal area of femur via osteotomy. The 4 mm defects were subsequently used for implantation studies where bone substitution materials of calcium phosphate cement, composites of collagen and silica, and iron foams with interconnecting pores were inserted. Different materials were partly additionally functionalized by strontium or bisphosphonate whose positive effects in osteoporosis treatment are well known. The lymphatic vessels were identified by immunohistochemistry using an antibody against podoplanin. Podoplanin immunopositive lymphatic vessels were detected in the granulation tissue filling the fracture gap, surrounding the implant and growing into the iron foam through its interconnected pores. Significant more lymphatic capillaries were counted at the implant interface of composite, strontium and bisphosphonate functionalized iron foam. A significant increase was also observed in the number of lymphatics situated in the pores of strontium coated iron foam. In conclusion, our results indicate the occurrence of lymphatic vessels in osteoporotic bone. Our results show that lymphatic vessels are localized at the implant interface and in the fracture gap where they might be involved in the removal of lymphocytes, macrophages, debris and the implants degradation products. Therefore the lymphatic vessels are involved in implant integration and fracture healing.

Healing of the bone with anti-fracture drugs

INTRODUCTION

Fracture healing is a complex process that leads to the restoration of tissue integrity through bone repair and represents a unique physiological characteristic of bone. Developing a better understanding of a fracture is essential to plan best noninvasive treatment for the patient. In osteoporosis, the patient who suffers of a fragility fracture is recommended to initiate a treatment with compounds active in preventing other low-energy skeletal trauma. Pharmaceutical industries are developing controlled clinical trials aiming to evaluate the capability of osteoporosis drugs to accelerate fracture healing.

AREAS COVERED

In preparing this review, a search was made with key words encompassing 'osteoporosis anti-fracture drugs and bone repair/healing', 'antiresorptives and bone repair/healing', 'bone-forming agents and bone repair/healing', and 'osteoporosis/anti-fracture drugs in fractures'. The results published in the area of the use of registered anti-fracture drugs to improve fracture repair and the efforts made to recommend measures for clinical outcomes in fracture healing acceleration are described in this report.

EXPERT OPINION

At present, the use of systemic pharmacological agents active to improve fracture healing by the clinicians is controversial and clinicians and scientists must do a better job in determining the methods of assessment for fracture healing.

A new metaphyseal bone defect model in osteoporotic rats to study biomaterials for the enhancement of bone healing in osteoporotic fractures

The intention of this study was to establish a new critical size animal model that represents clinically relevant situations with osteoporotic bone status and internally fixated metaphyseal defect fractures in which biomaterials for the enhancement of fracture healing in osteoporotic fracture defects can be studied. Twenty-eight rats were ovariectomized (OVX) and treated with a calcium-, phosphorus-, vitamin D3-, soy- and phytoestrogen-free diet. After 3months Dual-energy X-ray absorptiometry measurements showed statistically significant reductions in bone mineral density of the spine of -25.9% and of the femur of -21.3% of the OVX rats compared with controls, confirming osteoporosis in the OVX rats. The OVX rats then underwent either 3 or 5mm wedge-shaped osteotomy of the distal metaphyseal area of the femur that was internally stabilized with a T-shaped mini-plate. After 42days biomechanical testing yielded completely unstable conditions in the 5mm defect femora (bending stiffness 0Nmm(-2)) and a bending stiffness of 12,500Nmm(-2) in the 3mm defects, which showed the beginning of fracture consolidation. Micro-computed tomography showed statistically significant more new bone formation in the 3mm defects (4.83±0.37mm(2)), with bridging of the initial fracture defect area, compared with the 5mm defects (2.68±0.34mm(2)), in which no bridging of the initial defect was found. These results were confirmed by histology. In conclusion, the 5mm defect can be considered as a critical size defect model in which biomaterials can be tested.

Local erythropoietin injection in tibiofibular fracture healing

BACKGROUND

Erythropoietin (EPO), in addition to its function as an erythropoiesis regulator has a regenerative activity on some nonhematopoietic tissues. Animal studies have suggested a role for erythropoietin in bone healing.

OBJECTIVES

The present study aimed to evaluate the effects of local EPO injection in healing of tibiofibular fractures.

MATERIALS AND METHODS

In a prospective double blind study, 60 patients with tibiofibular fracture were divided to equal EPO or placebo groups, randomly. Patients received local injection of either EPO or a placebo to the site of fracture two weeks after surgical fixation. Patients were followed by clinical and radiographic examination to determine the union rate. The period of fracture union and incidence of nonunion were compared between the two groups.

RESULTS

The demographic data and types of fractures were similar in the both groups. The mean duration of the fracture union was 2.1 weeks shorter in those treated with EPO (P = 0.01). Nonunion was observed in 6 patients of the control group and 2 receiving EPO (P = 0.02). No patient experienced any adverse effect from local EPO injections.

CONCLUSIONS

EPO injection into the site of tibiofibular fractures may possibly accelerate healing.

Special Review: Accelerating fracture repair in humans: a reading of old experiments and recent clinical trials

Based on their mode of action and preclinical data, one would expect bisphosphonates to improve the healing of fractures in cancellous bone, and bone morphogenetic proteins (BMPs) to reduce the risk of non-union in severe shaft fractures. Parathyreoid hormone (PTH) can be expected to accelerate fracture healing in general. The clinical data in support of this is meager. Stimulation of cancellous bone healing and strength by bisphosphonates has been inadvertently shown in the context of implant fixation, but not convincingly in fractures per se. The clinical BMP literature is confusing, and the chance of ever demonstrating reduced numbers of non-union are small, due to power issues. Still, acceleration of 'normal' healing may be possible, but largely remains to show. For PTH, the two available clinical trials both show accelerated healing, but none of them is flawless, and there is a need for better studies.

Radiostereometric analysis in measurements of migration and inducible micromotion in intra-articular distal radius fractures treated with a volar plate

OBJECTIVES

This study examined the use of radiostereometric analysis (RSA) in the assessment of fixation stability and healing characteristics in intra-articular fractures of the distal radius treated with a volar locking plate.

DESIGN

Prospective cohort study.

SETTING

University hospital.

PATIENTS

Fifteen patients between 39 and 67 years of age with OTA type C distal radius fractures.

INTERVENTION

All fractures were treated with a locked volar plate, and tantalum markers were inserted into fracture fragments. RSA was performed at 2, 6, 12, 18, and 52 weeks postoperatively. RSA measurements were also performed using maximal voluntary grip to create inducible micromotion at the fracture site at 6, 12, 18, and 52 weeks.

MAIN OUTCOME MEASUREMENTS

Interfragmentary migration and inducible micromotion in terms of translation and rotation in 3 orthogonal axes were determined. The total translation and rotation were also calculated.

RESULTS

Precision of measurements along individual axes was between 0.08 and 0.17 mm and 0.70-0.94 degrees for migration and between 0.04 and 0.07 mm and 0.29 and 0.86 degrees for inducible micromotion. Fractures underwent significant translational and rotational migration (P = 0.004 for both) during the first 2 weeks after surgery. This permanent migration was not detectable on conventional radiographs. Inducible fracture micromotion, measured during maximal grip, was detectable up to 18 weeks, even after achievement of radiographic union.

CONCLUSIONS

RSA seems to have the potential to be a unique tool in redefining the biologic progress of fracture union. In plated fractures of the distal radius, the method is technically challenging due to difficulties in achieving a good scatter and visibility of tantalum RSA markers.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The tactics of modern-day regulatory trials

Fractures are an important public health problem affecting patients of all ages. Although most fractures heal quickly, some heal poorly and some do not heal at all. To achieve an optimal healing outcome, the standard of care for most fractures consists of reduction followed by immobilization, with a myriad of options regarding the approach to fracture-healing. Currently, biopharmaceutical companies are sponsoring research with regard to products that aim to enhance or accelerate fracture-healing; however, as there are no approved and marketed systemic therapies for fracture-healing, the development and commercialization process for such products will require close collaboration between industry, academia, and regulators to determine how to bring these products to market in the most efficient manner. The following manuscript provides a brief overview of the regulatory process in the United States for systemic therapies in fracture-healing and discusses key issues that may arise in connection with the regulatory approval of these novel investigational treatments.

Drugs for bone healing

INTRODUCTION

The biological process of fracture healing is complex with influences that are both patient-dependent and related to the trauma experienced and stability of the fracture. Fracture healing complications negatively affect the patient's quality of life, even more when fractures occur in the elderly osteoporotic patients.

AREAS COVERED

In the polytherapy for bone regeneration, a high success rate was obtained with the use of growth factors, osteogenic cells, and osteoconductive factors. There have been high expectations that treatment with drugs active on bone remodeling would be efficient for acceleration of fracture healing. A literature search was undertaken using wording like "drug or pharmacology of fracture healing." This report will review the systemic pharmacological agents for which clinical trials documenting their efficacy on bone healing have been carried out or are underway.

EXPERT OPINION

At present the use of systemic pharmacological agents to enhance fracture healing in the clinical setting is still controversial. However, future clinical trials will offer the possibility to obtain data that will make possible the registration of a drug as a "healer."

Implications for fracture healing of current and new osteoporosis treatments: an ESCEO consensus paper

Osteoporotic fracture healing is critical to clinical outcome in terms of functional recovery, morbidity, and quality of life. Osteoporosis treatments may affect bone repair, so insights into their impact on fracture healing are important. We reviewed the current evidence for an impact of osteoporosis treatments on bone repair. Treatment with bisphosphonate in experimental models is associated with increased callus size and mineralization, reduced callus remodeling, and improved mechanical strength. Local and systemic bisphosphonate treatment may improve implant fixation. No negative impact on fracture healing has been observed, even after major surgery or when administered immediately after fracture. Experimental data for denosumab and raloxifene suggest no negative implications for bone repair. The extensive experimental results for teriparatide indicate increased callus formation, improved biomechanical strength, and greater external callus volume and total bone mineral content and density. Case reports and a randomized trial have produced mixed results but are consistent with a positive impact of teriparatide on clinical fracture healing. Studies with strontium ranelate in models of fracture healing indicate that it is associated with improved bone microstructure, callus volume, and biomechanical properties. Finally, there is experimental evidence for a beneficial effect of some of the agents currently being developed for osteoporosis, notably sclerostin antibody and DKK1 antibody. There is currently no evidence that osteoporosis treatments are detrimental for bone repair and some promising experimental evidence for positive effects on healing, notably for agents with a bone-forming mode of action, which may translate into therapeutic applications.

Parathyroid hormone and bone healing

Fracture healing is a complex process, and a significant number of fractures are complicated by impaired healing and non-union. Impaired healing is prevalent in certain risk groups, such as the elderly, osteoporotics, people with malnutrition, and women after menopause. Currently, no pharmacological treatments are available. There is therefore an unmet need for medications that can stimulate bone healing. Parathyroid hormone (PTH) is the first bone anabolic drug approved for the treatment of osteoporosis, and intriguingly a number of animal studies suggest that PTH could be beneficial in the treatment of fractures and could thus be a potentially new treatment option for induction of fracture healing in humans. Furthermore, fractures in animals with experimental conditions of impaired healing such as aging, estrogen withdrawal, and malnutrition can heal in an expedited manner after PTH treatment. Interestingly, fractures occurring at both cancellous and cortical sites can be treated successfully, indicating that both osteoporotic and nonosteoporotic fractures can be the target of PTH-induced healing. Finally, the data suggest that PTH partly prevents the delay in fracture healing caused by aging. Recently, the first randomized, controlled clinical trial investigating the effect of PTH on fracture healing was published, indicating a possible clinical benefit of PTH treatment in inducing fracture healing. The aim of this article is therefore to review the evidence for the potential of PTH in bone healing, including the underlying mechanisms for this, and to provide recommendations for the clinical testing and use of PTH in the treatment of impaired fracture healing in humans.

Teriparatide improves early callus formation in distal radial fractures

BACKGROUND

Teriparatide (parathyreoid hormone; PTH 1-34) increases skeletal mass in humans and improves fracture healing in animals. A recent randomized multicenter trial of nonoperated distal radial fractures showed a moderate shortening of the time to restoration of cortical continuity by treatment with 20 microg (low-dose) teriparatide per day, but not with 40 microg (high-dose). As radiographic cortical continuity appears late in the healing process, perhaps too late for clinical relevance, we studied the qualitative appearance of the callus 5 weeks after fracture.

METHODS

One third of the patients of the international trial were treated at Linköping University Hospital. The multicenter trial did not evaluate early callus formation. We therefore made a blinded qualitative scoring of the callus at 5 weeks in our 27 patients. Callus formation was arbitrarily classified as rich, intermediate, or poor.

RESULTS

9 patients were classified as rich (none had received placebo, 3 low-dose teriparatide, and 6 high-dose teriparatide). 9 patients were classified as intermediate (1 had received placebo, 5 low-dose, and 3 high-dose). 9 patients were classified as poor (7 had received placebo, 1 low-dose, and 1 high-dose) (p < 0.001).

INTERPRETATION

This is a post hoc subgroup analysis of an outcome variable, which was not in the official protocol. The results must therefore be interpreted with caution. However, in combination with the results of the larger trial, the data suggest that radiographic quality at an early time point might be a sensitive variable, perhaps better than time to cortical continuity. Moreover, teriparatide appeared to improve early callus formation in distal radial fractures.

Teriparatide for acceleration of fracture repair in humans: a prospective, randomized, double-blind study of 102 postmenopausal women with distal radial fractures

Animal experiments show a dramatic improvement in skeletal repair by teriparatide. We tested the hypothesis that recombinant teriparatide, at the 20 microg dose normally used for osteoporosis treatment or higher, would accelerate fracture repair in humans. Postmenopausal women (45 to 85 years of age) who had sustained a dorsally angulated distal radial fracture in need of closed reduction but no surgery were randomly assigned to 8 weeks of once-daily injections of placebo (n = 34) or teriparatide 20 microg (n = 34) or teriparatide 40 microg (n = 34) within 10 days of fracture. Hypotheses were tested sequentially, beginning with the teriparatide 40 microg versus placebo comparison, using a gatekeeping strategy. The estimated median time from fracture to first radiographic evidence of complete cortical bridging in three of four cortices was 9.1, 7.4, and 8.8 weeks for placebo and teriparatide 20 microg and 40 microg, respectively (overall p = .015). There was no significant difference between the teriparatide 40 microg versus placebo groups (p = .523). In post hoc analyses, there was no significant difference between teriparatide 40 microg versus 20 microg (p = .053); however, the time to healing was shorter in teriparatide 20 microg than placebo (p = .006). The primary hypothesis that teriparatide 40 microg would shorten the time to cortical bridging was not supported. The shortened time to healing for teriparatide 20 microg compared with placebo still may suggest that fracture repair can be accelerated by teriparatide, but this result should be interpreted with caution and warrants further study.

Complication reporting in orthopaedic trials. A systematic review of randomized controlled trials

BACKGROUND

The nature and frequency of complications during or after orthopaedic interventions represent critical clinical information for safety evaluations, which are required for the development or improvement of orthopaedic care. The goal of this systematic review was to check whether essential data regarding the assessment of the prevalence, severity, and characteristics of complications related to orthopaedic interventions are consistently provided by the authors of papers on randomized controlled trials.

METHODS

Five major peer-reviewed orthopaedic journals were screened for randomized controlled trials published between January 2006 and July 2007. All relevant papers were obtained, anonymized, and evaluated by two external reviewers. A checklist consisting of three main parts (definition, evaluation, and reporting) was developed and applied for the assessment of complication reporting. The results were stratified into surgical and nonsurgical categories.

RESULTS

One hundred and twelve randomized controlled trials were identified. Although complications were included as trial outcomes in two-thirds of the studies, clear definitions of anticipated complications were provided in only eight trials. In 83% of the trials, the person or group assessing the complications was not identified. No trial involved a data safety review board for assessment and classification of complications.

CONCLUSIONS

The lack of homogeneity among the published studies that we reviewed indicates that improvement in the reporting of complications in orthopaedic clinical trials is necessary. A standardized protocol for assessing and reporting complications should be developed and endorsed by professional organizations and, most importantly, by clinical investigators.