Introduction. The presence of pluripotent mesenchymal cells in the periosteum along with the growth factors produced or released following injury provides this tissue with an important role in bone healing. Utilising this property, vascularised periosteal flaps may increase the union rates in recalcitrant atrophic long bone non-union. The novel chimeric fibula-periosteal flap utilises the periosteum raised on an independent periosteal vessel, thus allowing the periosteum to be inset freely around the osteotomy site, improving bone biology. Materials & Methods. Ten patients, with established non-union, underwent fibula-periosteal chimeric flaps (2016–2022) at the Canniesburn Plastic Surgery Unit, UK. Preoperative CT angiography was performed to identify the periosteal branches. A case-control approach was used. Patients acted as their own controls, which obviated patient specific risks for non-union. One osteotomy site was covered by the chimeric periosteal flap and one without. In two patients both the osteotomies were covered using a long periosteal flap. Results. Union rate of 100% (11/11) was noted with periosteal flap osteotomies, versus those without flaps at 28.6% (2/7) (p = 0.0025). Time to union was also reduced in the periosteal flaps at 8.5 months versus 16.75 months in the control group (p = 0.023). Survival curves with a hazard ratio of 4.1, equating to a 4 times higher chance of union with periosteal flaps (log-rank p = 0.0016) was observed. Conclusions. The chimeric fibula-periosteal flap provides an option for atrophic recalcitrant non-unions where use of vascularised fibula graft alone may not provide an adequate biological environment for consolidation

Tendon healing is a complex process that often results in compromised healing of the tendon tissue. It has recently been shown that temporal changes in the expression profile and the histological tissue quality of the tendons occur during the early healing process after acute Achilles tendon rupture. Whether these changes are accompanied by an altered healing process, is not yet known and was the aim of the present study. Tendon biopsies were obtained from 24 patients with acute Achilles tendon rupture at the time of surgery (2–9 days after rupture) and examined histologically as well as on RNA level. Histologically, the tendon architecture, the amount of aligned collagen, glycosaminoglycan and fat as well as the cellularity, vascularity and immune cell infiltration were determined. On RNA level the expression of markers for the modeling/remodeling (MMPs and TIMPs), collagens (1, 3, 5), tendon markers (scleraxis, tenomodulin), pro- and anti-inflammatory markers (IL-1beta, IL6, IL10, IL33, TNFa, TGF-beta1, COX2) and immune cell markers (CD3, CD68, CD80, CD206) were analyzed by Real-Time PCR. To determine the clinical outcome, the patients were followed up 12 months after the operation and the following scores were recorded: Subjective score, Tegner score, Visual Analog Scale (VAS) pain, VAS function, Matles Test, Achilles tendon total rupture score (ATRS), Therman 100-points score, Heel rise test. Statistics: Spearman correlation analysis. Correlation analysis shows that early post-rupture surgery is associated with better clinical outcome (ATRS Score: p=0.022). Histologically, a good functional healing outcome shows a positive correlation to the amount of aligned collagen (Heel Rise Test: p = 0.009) and glycosaminoglycans in the tendon (Heel Rise Test: p = 0.026, Matles difference: p = 0.029), as well as a negative correlation to the fat content (Thermann score: p = 0.018, subjective score: p = 0.027, VAS function: p = 0.031). On RNA level, a good healing outcome correlates with increased expression of MMP13, collagen 1, 3, 5 (Heel Rise Test: p = 0.019, p = 0.048, p = 0.030), and TIMP2 (Tegner Score: p = 0.040), TGF-beta1 (Thermann Score: p = 0.032) and CD80 (ATRS: p = 0.025, Thermann score:, p = 0.032). Whereas a limited healing outcome is associated with an increased expression of MMP2 (Heel Rise Test: p = 0.033), MMP3 (Matles Test: p=0.001, Heal Rise test p = 0.017), and IL33 (Tegner Score: p = 0.047). The results of the study show a clear relationship between the tendon biology at the time of the surgery and the clinical and functional healing outcome 12 months after the operation. Especially matrix formation and remodeling play a crucial role, while the examined immunological factors seem to influence the tendon healing to a lesser extent. The modulation of matrix formation could potentially lead to improved treatment options in the future

Remodeling of the cancellous bone is more active than that of the cortical bone. It is known that the remodeling is governed by the intracancellous fluid pressure. Particularly, the lacunocanalicular pore (PLC) fluid pressure (FP) is essential for survival of the osteocyte and communication of remodeling signals between the PLC and intertrabecular pore (PIT). As a result, knowledge about the PLCFP generation of trabeculae is required to understand human cancellous bone biology. At this moment, the PLCFP measurement of human trabeculae is not reported. The purpose of this study was a direct measurement of PLCFP generation of human proximal femoral trabeculae in the direction of superior-to-fovea. Twenty one microscopic cylindrical trabecular specimens from trabeculae of five fresh human proximal femur (75 to 77 years) were fabricated using a micro-milling machine composed of the laser (Teemphotonics: 532nm), 3-dimensional PZT stage (PI Gmbh, resolution: 0.5nm), and microscope (lens: Navitar, and CCD: Hitachi) with the image processor. The fabrication resolution of the micro-milling machine was 0.4 um. Based on the trabecular trajectory of femoral head, the specimens were obtained in the direction of superior-to-fovea. The cylindrical specimen size had 120 um in diameter and 240 um in length. The test methods described in the previous study were utilized. The used undrained uniaxial strain condition could induce the maximum PLCFP within the trabecular elastic limit. The measured trabecular PLCFP (±SD) at the strain of 0.4% was 693.7±79.1 kPa. Since this experiment is equivalent to the instantaneous response of PLCFP with free flow boundaries after application of an extremely fast loading speed such an ideal step loading, a PLCFP generation in the physiological condition will be much less than the results obtained in this study. Base on the linear isotropic poroelasticity, the obtained Skempton's coefficient is almost 0. Thus, the load bearing capability by trabecular PLC fluid is negligible. The Biot coefficient is 0.35 which is higher than that of the cortical tissue (0.14). As a result, the intraosseous fluid communication through trabecular surfaces is active compared to that through Haversian canal surfaces. This imply that mass transports from the trabecular PLC into the PIT and from the PIT into the trabecular PLC could be significantly affected by the PITFP (the physiological blood systolic and diastolic pressure: 16 and 11 kPa, respectively) that acts as the FP boundary condition for the PLC flow. It is known that the PLC flow generates the electrical charges on the trabecular surface (‘+’ for being spouted into the PIT and ‘−’ for being flown into the PLC), which control differentiation and proliferation of the osteoblast and mesenchymal stem cell. Thus, significant changes in the PITFT could cause changes in the intra-trabecular PLC flow characteristics, mass transports between the PLC and PIT, and electrical charges on the trabeculae. Eventually, these could result in pathologies related to the trabecular remodeling

Impaired bone healing biology secondary to soft tissue deficits and chemotherapy contribute to non-union, fracture and infection following limb salvage surgery in Osteosarcoma patients. Approved bone healing augments such as recombinant human bone morphogenetic protein-2 (rhBMP-2) have great potential to mitigate these complications. rhBMP-2 use in sarcoma surgery is limited, however, due to concerns of pro-oncogenic signalling within the tumour resection bed. To the contrary, recent pre-clinical studies demonstrate that BMP-2 may induce Osteosarcoma differentiation and limit tumour growth. Further pre-clinical studies evaluating the oncologic influences of BMP-2 in Osteosarcoma are needed. The purpose of this study is to evaluate how BMP-2 signalling affects Osteosarcoma cell proliferation and metastasis in an active tumour bed. Two Osteosarcoma cell lines (143b and SaOS-2) were assessed for proliferative capacity and invasion. 143b and SaOS-2 cells were engineered to upregulate BMP-2. In vitro proliferation was assessed using a cell viability assay, motility was assessed with a scratch wound healing assay, and degree of osteoblastic differentiation was assessed using qRT-PCR of Osteoblastic markers (CTGF, ALP, Runx-2 and Osx). For in vivo evaluation, Osteosarcoma cells were injected into the intramedullary proximal tibia of immunocompromised (NOD-SCID) mice and local tumour growth and metastases were assessed using weekly bioluminescence imaging (BLI) and tumour volume measurements for 4–6 weeks. At the experimental end point we assessed radiographic tumour burden using ex-vivo micro-CT, as well as tibial and pulmonary gross and histologic pathology. SaOS-2 was more differentiated than 143b, with increased expression of Runx-2 (p = 0.009), Osx (p = 0.004) and ALP (p = 0.035). BMP-2 upregulation did not stimulate an osteoblast differentiation response in 143b, but stimulated an increase in Osx expression in SaOS-2 (p = 0.002). BMP-2 upregulation in 143b cells resulted in increased proliferation in vitro (p = 0.014), faster in vitro wound healing (p = 0.03), significantly increased tumour volume (p = 0.001) with enhanced osteolysis detected on micro-CT, but did not affect rates of lung metastasis (67% vs. 71%, BMP-2 vs. Control). BMP-2 over-expression in SaOS-2 cells reduced in vitro proliferation when grown in partial osteogenic-differentiation media (p < 0.001), had no effect on in vitro wound healing (p = 0.28), reduced in vivo SaOS-2 tumour burden at 6 weeks (photon counts, p < 0.0001), decreased tumour-associated matrix deposition as assessed by trabecular thickness (p = 0.02), and did not affect rates of lung metastasis (0% vs. 0%). Our results indicate BMP-2 signalling incites a proliferative effect on a poorly differentiated Osteosarcoma cell line (143b), but conditionally reduces proliferative capacity and induces a partial differentiation response in a moderately-differentiated Osteosarcoma cell line (SaOS-2). This dichotomous effect may be due to the inherent ability for Osteosarcoma cells to undergo BMP-2 mediated terminal differentiation. Importantly, these results do not support the clinical application of BMP-2 in Osteosarcoma limb salvage surgery due to the potential for stimulating growth of poorly differentiated Osteosarcoma cells within the tumour bed. Additional studies assessing the effects of BMP-2 in an immune-competent mouse model are ongoing

Impaired bone healing biology secondary to soft tissue deficits and chemotherapy contribute to non-union, fracture and infection following limb salvage surgery in Osteosarcoma patients. Approved bone healing augments such as recombinant human bone morphogenetic protein-2 (rhBMP-2) have great potential to mitigate these complications. rhBMP-2 use in sarcoma surgery is limited, however, due to concerns of pro-oncogenic signalling within the tumour resection bed. To the contrary, recent pre-clinical studies demonstrate that BMP-2 may induce Osteosarcoma differentiation and limit tumour growth. Further pre-clinical studies evaluating the oncologic influences of BMP-2 in Osteosarcoma are needed. The purpose of this study is to evaluate how BMP-2 signalling affects Osteosarcoma cell proliferation and metastasis in an active tumour bed. Two Osteosarcoma cell lines (143b and SaOS-2) were assessed for proliferative capacity and invasion. 143b and SaOS-2 cells were engineered to upregulate BMP-2. In vitro proliferation was assessed using a cell viability assay, motility was assessed with a scratch wound healing assay, and degree of osteoblastic differentiation was assessed using qRT-PCR of Osteoblastic markers (CTGF, ALP, Runx-2 and Osx). For in vivo evaluation, Osteosarcoma cells were injected into the intramedullary proximal tibia of immunocompromised (NOD-SCID) mice and local tumour growth and metastases were assessed using weekly bioluminescence imaging and tumour volume measurements for 4–6 weeks. At the experimental end point we assessed radiographic tumour burden using ex-vivo micro-CT, as well as tibial and pulmonary gross and histologic pathology. SaOS-2 was more differentiated than 143b, with significantly increased expression of the Osteoblast markers Osx (p = 0.004) and ALP (p = 0.035). BMP-2 upregulation did not stimulate an osteoblast differentiation response in 143b, but stimulated an increase in Osx expression in SaOS-2 (p = 0.002). BMP-2 upregulation in 143b cells resulted in increased proliferation in vitro (p = 0.014), faster in vitro wound healing (p = 0.03), significantly increased tumour volume (p = 0.001) with enhanced osteolysis detected on micro-CT, but did not affect rates of lung metastasis (67% vs. 71%, BMP-2 vs. Control). BMP-2 over-expression in SaOS-2 cells reduced in vitro proliferation when grown in osteogenic-differentiation media (p < 0.001), had no effect on in vitro wound healing (p = 0.28), reduced in vivo SaOS-2 tumour burden at 6 weeks (photon counts, p < 0.0001), decreased tumour-associated matrix deposition as assessed by trabecular thickness (p = 0.02), but did not affect rates of lung metastasis (0% vs. 0%). Our results indicate BMP-2 signalling incites a proliferative effect on a poorly differentiated Osteosarcoma cell line (143b), but conditionally reduces proliferative capacity and induces a partial differentiation response in a moderately-differentiated Osteosarcoma cell line (SaOS-2). This dichotomous effect may be due to the inherent ability for Osteosarcoma cells to undergo BMP-2 mediated terminal differentiation. Importantly, these results do not support the clinical application of BMP-2 in Osteosarcoma limb salvage surgery due to the potential for stimulating growth of poorly differentiated Osteosarcoma cells within the tumour bed. Additional studies assessing the effects of BMP-2 in an immune-competent mouse model are ongoing

The establishment of a proper musculoskeletal system depends on the well-organized and synchronized development of muscle, tendon and cartilage/bone. In tendon biology, a great progress in identifying tendon-specific genes (Scleraxis, Mohawk, Tenomodulin) had been made in the last decade. However, there are many open questions regarding the exact function of genes in tendon development and homeostasis. The purpose of this study was to perform a systematic review of publications describing tendon-related genes, which were studied in-depth and characterized by using knockout technologies and the respectively generated transgenic mouse. Method: Literature search was carried out in Pubmed using “tendon” and “mouse knockout” and “phenotype” and was not limited to year. Results: We report in a tabular manner, that from a total of 25 tendon-related genes, in 23 of the respective knockout mouse models phenotypic changes were detected. Additionally, in some of the models it was described at which developmental stages these changes appeared and progressed. Interestingly, so far only loss of Scleraxis and TGFbeta signaling led to severe tendon developmental phenotypes, while mice deficient for various proteoglycans, Mohawk, EGR1 and 2, and Tenomodulin exhibited mild phenotypes. This suggests that in general the tendon developmental program is well backup and specifically that among the members of the proteoglycan family there are clear compensatory effects. In future, it will be of great importance to discover additional master tendon transcription factors as well as genes that play indispensable roles in tendon development

Surgical reconstruction of the injured Anterior Cruciate Ligament (ACL) is an effective solution to knee instability, but not all grafts incorporate well. The biological environment in the knee that controls graft integration is not well understood, and this study aims to fill that gap as the first step towards a translational approach to optimise outcomes. Over two stages, tissue samples and knee fluid samples were harvested from patients undergoing ACL reconstruction. These samples were cultured and stored to allow batch analysis for a variety of cytokines, growth factors and collagenases. Stage 1 (n=14) identified the presence of specific pro-inflammatory cytokines, growth factors and latent collagenase. Information gathered allowed a more targeted approach to be used in stage 2 (n=18). Stage 2 data from tissue cultures suggest that collagenase activity peaks later than 6 hours post-op. The relationships between collagenase activity and levels of TNF-alpha, IL-1beta and bFGF are of potential interest, and the profiles of patients will be compared with longer term follow-up data to determine any effects on outcomes. Further detailed assessment of the biology of ACL graft incorporation is required, but these preliminary data have clarified some of the details worthy of further study

Aims: Identifying low-grade infection in failed total hip replacements (THR) is an important but often difficult task. Recently, there has been interest in the use of molecular biology techniques as potential sensitive tests for low-grade infection by identifying fragments of bacterial DNA within human tissue. Methods: We investigated the ability of a molecular biology technique known as the polymerase chain reaction (PCR) to identify low-grade infection during revision of THR considered to have failed from aseptic causes. We analysed 113 specimens of tissue and synovial fluid from 31 THR revised for aseptic loosening and compared them to 105 control specimens taken during 28 primary THR. All cases were performed in laminar flow theatres. No primary or revision specimen had positive microbiological cultures. No revision specimen had histological evidence suggestive of infection. Results: Using PCR, we identified bacterial DNA in 39 of 85 revision THR tissue specimens (46%) compared to 18 of 84 primary THR specimens (21.4%, p=0.001). Bacterial DNA was identified within the synovial fluid in three specimens taken from 28 revision THR (10.7%) and in two specimens taken from 21 primary THR (9.5%, p=0.36). As multiple specimens were sent per case, 16 of 31 revision THR (52%) and eight of 28 primary THR (29%) were considered to be infected (p=0.072). Conclusions: Our results suggest that many aseptically loose revision THR actually contain bacterial DNA within the peri-prosthetic tissue, but infrequently within the synovial fluid. With an overall specimen contamination rate of 19%, however, PCR has poor specificity for routine diagnostic use in revision THR

Osteosarcoma despite considerable biological and molecular heterogeneity, being defined by a phenotypic program resulting in the production of osteoid, is a relatively consistent clinical entity. Over the past 20 years a large catalogue of genetic alterations present in osteosarcoma has been compiled, but unfortunately this information has yielded little biological understanding or widely accepted prognostic factor. In an analogous manner nearly two decades of clinical trials, most incorporating new agents or intensifying therapy have not further improved the prognosis of patients with osteosarcoma. This would lead to considerable pessimism if it were not for the dramatic expansion in availability of osteosarcoma models, tissues resources as well as new agents, particularly antibodies targeted to various cell surface receptor proteins. Selecting and applying these agents will require an understanding of osteosarcoma’s unique dependencies and may also have the potential to yield biological insights. Defining these dependencies has been complicated by osteosarcoma’s genetic complexity as well as redundant expression of cell surface receptors, but efficacy of antibody-based targeted therapies may assist in defining the relative importance of receptors as well as their downstream signal transduction pathways. The availability of these new tissue resources and murine models may assist in understanding osteosarcoma’s complex biology, aid identification of biological features that can serve as prognostic factors as well as assist in the selection of new agents for clinical trials. These new resources may permit one to define the feasibility of performing a biologically based treatment selection and may have implications for cooperative group interaction. During this presentation the molecular biology of osteosarcoma will be reviewed, the available tissue resources and models will be outlined, some of the preliminary data available thus far will be presented, and this will be placed in the context of ongoing as well as planned phase 1 and phase 2 osteosarcoma clinical trials

In developed nations Charcot arthropathy is most commonly caused by diabetes mellitus. Worldwide, leprosy remains the primary cause. All evidence points to a relationship between neurologic loss, continued loading activities and the development of unrecognized bone fragmentation. In type 2 diabetes, dysregulation of leptin biology causes bone loss and may be an important factor in precipitating Charcot events. Bone density studies show massive loss of bone in patients with ankle and hindfoot Charcot problems, but not midfoot problems. This suggests a different mechanism for collapse. Stable collapse with ulcer development in the midfoot can be treated with exostectomy. Realignment and fusion remain the mainstays of treatment for diabetic Charcot neuropathy, especially in the ankle and hindfoot. Bone mineralization deficiencies require special consideration of fixation techniques. Thin wire external fixation – either as primary fixation or to reinforce/neutralize other methods can be very helpful. Large bridging screws and carefully selected bridging plates are frequently also valuable to consider. Excessive immobilization periods (often double the normal amount of time) are generally required. The goal may be limited to a braceable, plantigrade foot

Massive uncontained glenoid defects are a difficult surgical problem requiring reconstruction in the setting of either primary or revision total shoulder arthroplasty. Our aim is to present a new one-stage technique that has been developed in our institution for glenoid reconstruction in the setting of massive uncontained glenoid bone loss. We utilise a modified delto-pectoral approach to perform our dual biology allograft autograft glenoid reconstruction. The native glenoid and proximal femoral allograft are prepared and shaped to create a precisely matched contact surface, which permits axial compression to secure fixation. The surface of the glenoid is lateralised to at least the level of the coracoid. The central cancellous femoral allograft is removed and impaction autografting is performed prior to implantation of a glenoid base plate with 25-mm long centre peg. Two screws are inserted into the best quality native scapular bone available to ensure compression. A reverse shoulder arthroplasty is implanted. We have performed our dual-biology reconstruction of the glenoid in combination with reverse total shoulder arthroplasty in 8 patients to date. The technique has been performed in the setting of massive uncontained glenoid defects without prostheses as well as in revisions from failed hemiarthroplasties and total shoulder arthroplasties. Our post-operative follow-up is now up to 32 months. CT scanning as early as 6 months demonstrates incorporation of the graft. There has been no evidence of loosening. None of our cases have been complicated by infection or peri-prosthetic fracture and there have been no dislocations. One patient sustained an acromial stress fracture at 9 months post-operatively after lifting a 100-pound gas cylinder. This was diagnosed on bone scan, had no impact on the construct and was managed in a sling for comfort. Another patient has developed Nerot grade I notching which substantially in all patients, with an average improvement of 6.6 on a 10-point scale. Our dual biology allograft-autograft reconstruction is a useful and elegant technique in the setting of massive uncontained defects of the glenoid, which permits the implantation of a reverse total shoulder arthroplasty. We believe this technique to be reproducible and uses materials that are both readily available and familiar

Summary Statement. Dickkopf-3 is upregulated in OA cartilage and synovial tissue. In vitro studies show Dkk3 can prevent cartilage degradation and antagonise Wnt signaling. We hypothesis that Dkk3 can protect against OA-related cartilage destruction. Introduction. Our group has previously shown that Dkk3, a member of the Dkk family of Wnt antagonists, is upregulated in OA cartilage and synovium. Levels of Dkk3 in synovial fluid are also increased in individuals with tricompartmental OA and after arthroscopy. The role of Dkk3 in cartilage or the factors regulating its expression are not currently understood. Correct regulation of cell signalling pathways is integral to cartilage homeostasis and thus the prevention of OA pathogenesis. Dkk3 is a member of the Dkk family of Wnt antagonists and therefore may impact on chondrocyte biology through interaction with the Wnt pathway. Dkk3 has also been found to influence TGFβ signalling in other cell systems. Methods. Expression of Dkk3 was assessed in primary human articular chondrocytes (HAC) following treatment with interleukin-1,-6 (IL1, IL6), TNFα, FGF2 and oncostatin-M (OSM). Dkk3 expression was assessed following ex vivo injury of murine cartilage explants. The effect of Dkk3 on IL1/OSM-induced proteoglycan and collagen release from explants of bovine nasal (BNC)- and primary human-cartilage was assessed. SW1353 chondrosarcoma cells were treated with Dkk3+/−Wnt3a, TGFβ and Activin and TOPFlash and CAGA luciferase reporters used to measure Wnt and Smad signalling. RNA was extracted from primary HAC treated with Dkk3+/−TGFβ or Wnt3a. ADAM12 and TIMP3 expression were measured to assess TGFβ signalling and AXIN2 to assess Wnt signalling. Micromass HAC were treated with Wnt3a +/− Dkk3 and proteoglycan output assessed using alcian blue staining. β-catenin was silenced in primary HAC prior to TGFβ and Activin treatment. Dkk3 was silenced in primary HAC for microarray analysis. Results. Dkk3 expression was decreased in primary HAC following IL1/OSM treatment but increased by TNFα. Dkk3 expression was decreased immediately following injury to murine explants. In BNC explants, IL1/OSM-induced proteoglycan release was inhibited by Dkk3. Dkk3 antagonised chondrocyte Wnt signalling and Wnt3a-induced reductions in proteoglycan production in micromass cultures. Interestingly, Dkk3 enhanced TGFβ signalling, increasing TGFβ-induced TIMP3 and ADAM12 expression and TGFβ-induced luciferase from the CAGA-luc reporter. In contrast Dkk3 antagonised Activin-induced CAGA-luc activity, TIMP3 and ADAM12 expression. β-catenin knockdown did not significantly alter TGFβ- or Activin-induced expression of TIMP3 or ADAM12, suggesting that Dkk3-effects on these pathways is not mediated solely by inhibition of Wnt signalling. Conclusions. Dkk3 expression is increased in OA and can be regulated injury and inflammatory cytokines. This suggests a balance of Dkk3 effects depending upon the biological stimuli within the cartilage. Dkk3 may act in a protective role in the presence of inflammatory cytokines as exemplified by its ability to inhibit matrix loss. Dkk3 knockdown decreases DICER expression and thus changes in Dkk3 expression in OA may alter chondrocyte phenotype through alterations in miRNA activity. The ability of Dkk3 to antagonise Wnt, enhance TGFβ and antagonise Activin signalling would have multiple effects on chondrocyte activity. These results imply that Dkk3 could influence multiple OA-relevant processes, protect cartilage from degradation and be important in cartilage development and homeostasis

Introduction

Intervertebral disc degeneration has been associated with low back pain (LBP) which is a major cause of long-term disability worldwide. Observed mechanical and biological modifications have been related to decreased water content.

Clinical traction protocols as part of LBP management have shown positive outcomes. However, the underlying mechanical and biological processes are still unknown.

The study purpose was to evaluate the impact of unloading through traction on the mechanobiology of healthy bovine tail discs in culture.

Cigarette smoking has a negative impact on the skeletal system by reducing bone mass and increasing the risk of fractures through its direct or indirect effects on bone remodeling. Recent evidence shows that smoking causes an imbalance in bone turnover, making bone vulnerable to osteoporosis and fragility fractures. In addition, cigarette smoking is known to have deleterious effects on fracture healing, as a positive correlation has been shown between the daily number of cigarettes smoked and years of exposure to smoking, although the underlying mechanisms are not fully understood. Smoking is also known to cause several medical and surgical complications responsible for longer hospital stays and a consequent increase in resource consumption. Smoking cessation is, therefore, highly advisable to prevent the onset of metabolic bone disease. However, some of the consequences appear to continue for decades. Based on this evidence, the aim of our work was to assess the impact of smoking on the skeletal system, particularly bone fractures, and to identify the pathophysiological mechanisms responsible for the impairment of fracture healing. Because smoking represents a major public health problem, understanding the association between cigarette smoking and the occurrence of bone disease is necessary in order to identify potential new targets for intervention.

RNA-Seq or whole transcriptome shotgun sequencing has been adopted in the last years as a reference technique to determine the presence and the quantity of different species of RNA in determined biological samples, thanks to it allows the identification every single RNA species transcribed from a reference genome. Meta-profiling takes advantage of the public availability of an increasing set of RNA-Seq data produced by different laboratories to summarize the expression levels of the different RNA species of many samples according to their biological context, giving the opportunity to perform comparisons on the gene expression profiles of different tissues by integrating data derived from a high number of studies. By using Genevestigator™; a platform which integrates RNA-Seq data into meta-profiles, we have performed a comparison between the gene expression profiles of bone, cartilage, muscle tendon and skin by means of interrogating its database with different gene sets and families with relevance to the function of the tissues of the musculoskeletal system. The collagen gene family and genes coding for proteoglycans, matrix metalloproteinases and tissue inhibitors of metalloproteinases, mechanotransduction-related proteins and signalling pathways involved in tissue development and differentiation have been analysed. Hierarchical clustering for every gene set was performed for the understanding the differences and similarities between the different tissues included in the analyses. The results of this study will help to improve our understanding of the musculoskeletal system, and will help to identify new biomarkers and signalling pathways of specific relevance for the bone, cartilage, muscle and tendon.

In cementless fixation system, surface character becomes important factor. Alkali and heat treatments on titanium metal has been proved to show strong bonding to bone and higher ongrowth rate. In this study we examined the effect of alkali and heat treatments on titanium rod in rabbit femur intramedurally model, in consideration of cementless hip stem. The implant had a 5mm in diameter and 25 mm in length. The implants were and half of them were immersed in 5 mol/L sodium hydroxide solution and heated at 600 åé for one hour (AH implant), and the other half were untreated (CL implant). The implants were implanted into the distal femur of the rabbits, AH implant into left femur and CL implants into right. The bone-implant interfaces were evaluated at 3, 6, and 12 weeks after implantations.

Pull-out tests showed that AH implants significantly higher bonding strength to bone than CL implants at each week after operations. At 12 weeks mean pull-out load of AH implants was 411.7 N and that of CL implants 72.2 N. As postoperative time elapsed, histological examination revealed that new bone form on the surface of the both types of the implants, but significantly more bone contacted directly on the surface of AH implants. At 12 weeks AH implant was covered by the newly formed bone about 56% of the whole surface of the implants and CL implants was about 19%.

In conclusion, alkali- and heat-treated titanium offers strong bone-bonding and high affinity to bone instead of conventional mechanical interlocking mechanism. Alkali and heat treatments on titanium may be applicable to the surface treatment for cementless joint replacement implant.

Anteromedial Osteoarthritis of the Knee (AMOA) is a distinct phenotype of OA. Within this pattern of disease, the anterior third of the medial tibial plateau exhibits full thickness cartilage loss. The middle third has damaged partial thickness cartilage, and the posterior third has retained cartilage, which is seen on macroscopic visual assessment to be normal. This study investigates the molecular features of progressive severities of cartilage damage within this phenotype.

Ten medial tibial plateau specimens were collected from patients undergoing unicompartmental knee replacements. The cartilage within the area of macroscopic damage was divided into equal thirds: T1(most damaged), to T3 (least damaged). The area of macroscopically undamaged cartilage was taken as a 4th sample, N. The specimens were prepared for histological (Safranin-O) and immunohistochemical analysis (Type I and II Collagen, proliferation and apoptosis). Immunoassays were undertaken for Collagens I and II and GAG content. Real time PCR compared gene expression between areas T and N.

There was a decrease in OARSI grade across the four areas, with progressively less fibrillation between areas T1, T2 and T3. Area N had a grade of 0 (normal). The GAG immunoassay showed decreased levels with increasing severity of cartilage damage (p< 0.0001). Proliferation and apoptosis, as expected, were increased in the more damaged areas. There was no significant difference in the Collagen II content or gene expression between areas. The Collagen I immunohistochemistry showed increased staining within chondrocyte pericellular areas in the undamaged region (N) and immunoassays showed that the Collagen I content of this macroscopically and histologically normal cartilage, was significantly higher than the damaged areas (p< 0.0001). Furthermore, real time PCR showed a significant increase in Collagen I expression in the macroscopically normal areas compared to the damaged areas (p=0.04).

We conclude that in this phenotype the Collagen I increase, in areas of macroscopically and histologically normal cartilage, may represent very early changes of the cartilage matrix within the osteoarthritic disease process. This may be able to be used as an assay of early disease and as a therapeutic target for disease modification or treatment.

Tissue engineering is a rapidly expanding field of research. Bone and cartilage engineering are being undertaken in an attempt to treat osteoarthritis and repair bone defects. In spite of extensive research little successful clinical application of this work has been seen. There are however many advances in the field that one day may have therapeutic interest. One particular area of interest is the potential for using osteophyte tissue in repairing osteoarthritic defects. Osteophytes represent an attempt by the body to regenerate bone and cartilage. They present an obvious source of cells for tissue engineering. Research ay QUT has shown that cells within the osteophytes are a better source of bone and cartilage regeneration in the laboratory than matched patient’s bone marrow stem cells.

Osteoarthritis remains the ultimate challenge for orthopaedic tissue engineering. Understanding the chemical and mechanical signals occurring in osteoarthritis presents opportunities for targeted drug delivery and potential slowing of disease. We have identified changes within the MMP profile of cells at the osteochondral junction. Subchondral sclerosis appears to be associated with changes in the nature of chondrocytes deep within the cartilage layer. This transformation of chondrocytes into osteoblast-like tissue in many ways mimics the changes seen in the growth plate once maturity is reached. Understanding the parallels between these processes may help answer some of the mechanisms of the development of osteoarthritis.

This talk will discuss the above topics as well as other areas of interest to an orthopaedic surgeon working within a group of 10 cell biologists.

Pathological assessment of periprosthetic tissues is important, not only for diagnosis, but also for understanding the pathobiology of implant failure. The host response to wear particle deposition in periprosthetic tissues is characterised by cell and tissue injury, and a reparative and inflammatory response in which there is an innate and adaptive immune response to the material components of implant wear. Physical and chemical characteristics of implant wear influence the nature of the response in periprosthetic tissues and account for the development of particular complications that lead to implant failure, such as osteolysis which leads to aseptic loosening, and soft-tissue necrosis/inflammation, which can result in pseudotumour formation. The innate response involves phagocytosis of implant-derived wear particles by macrophages; this is determined by pattern recognition receptors and results in expression of cytokines, chemokines and growth factors promoting inflammation and osteoclastogenesis; phagocytosed particles can also be cytotoxic and cause cell and tissue necrosis. The adaptive immune response to wear debris is characterised by the presence of lymphoid cells and most likely occurs as a result of a cell-mediated hypersensitivity reaction to cell and tissue components altered by interaction with the material components of particulate wear, particularly metal ions released from cobalt-chrome wear particles.

Cite this article: Professor N. A. Athanasou. The pathobiology and pathology of aseptic implant failure. Bone Joint Res 2016;5:162–168. DOI: 10.1302/2046-3758.55.BJR-2016-0086.

Recently, secondary life-threatening inflammatory reactions have been identified with molecular biological techniques in patients with multi-system injuries who were submitted to immediate or early intramedullary fixation of their fractured femora. This phenomenon was called “The second hit”, and it caused ARDS, PE, and Renal Failure.

In a consecutive series of 135 trauma patients with high energy long bone fractures, 40 had sustained multiple-injuries. All fractures were reduced and stabilized on admission by AO-Tubular External Fixation systems. After 72–96 hours, this system was converted to an hybrid-ring-tubular system, which had three dimensional stability. They commenced partial weight bearing 24 hours later, and were followed by bony union.

One patient developed DVT, none developed ARDS, PE, Renal Failure.

Superficial pin-tract infection was common, but no-deep infection and’or osteomyelitis were encountered.

With this minimal-invasive surgical technique, life threatening complications were avoided while preserving the integrity of the soft tissue envelope, the critical contributing biological factor for fracture healing.