Injuries to the spinal cord may be associated with increased healing of fractures. This can be of benefit, but excessive bone growth can also cause considerable adverse effects. We evaluated two groups of patients with fractures of the spinal column, those with neurological compromise (n = 10) and those without (n = 15), and also a control group with an isolated fracture of a long bone (n = 12). The level of transforming growth factor-beta (TGF-β), was measured at five time points after injury (days 1, 5, 10, 42 and 84). The peak level of 142.79 ng/ml was found at day 84 in the neurology group (p < 0.001 vs other time points). The other groups peaked at day 42 and had a decrease at day 84 after injury (p ≤ 0.001). Our findings suggest that TGF-β may have a role in the increased bone turnover and attendant complications seen in patients with acute injuries to the spinal cord

Whilst the SIGN Guidelines state that the use of prophylactic antibiotics in surgery unequivocally reduces major morbidity, reduces hospital costs and is likely to decrease overall consumption of antibiotics they state the chosen antibiotics must reflect local, disease-specific information about the common pathogens and their antimicrobial susceptibility. Growing healthcare concern regarding the rates of Clostridium Difficile (C. Diff) within the hospital setting have led to rationalised and better streamlined prescribing practice within the NHS. In NHS Lanarkshire this led to revised guidelines for prophylactic antibiotic use in Orthopaedics in 2010. Routine use of 3. rd. generation Cephalosporin has been replaced by Flucloxacillin 1g and Gentamicin 1mg/kg. Anecdotally the surgeons within our department were concerned that they were recognising more post-operative renal impairment than before 2010. Our study took 902 consecutive cases treated surgically with either Total Hip Replacement, Total Knee Replacement, Dynamic Hip Screw for fracture and Hemiarthroplasty for fracture since the introduction of the new antibiotic policy. We compared this with a similar number of cases treated with the same operations pre-2010. We looked at the pre admission Urea & Electrolystes compared with immediate post-operative results and applied the definition of Acute Kidney Injury (AKI) as defined by the Acute Kidney Injury Network. A. A rapid time course (less than 48 hours) and B. Reduction of kidney function either as an absolute increase in serum creatinine of ≥26.4μmol/l (≥0.3 mg/dl) or a percentage increase in serum creatinine of ≥50%. Based on this definition we found an increased rate of AKI of 13.7% after the introduction of the use of Gentamicin from 9.8% before its routine use. We wish to highlight that the routine widespread use of Gentamicin may be increasing the rate of acute renal dysfunction seen in Orthopaedic patients undergoing major surgery

Background. Polytrauma patients are at high risk of systematic inflammatory response syndrome (SIRS) due to an exaggerated unbalanced immune response that can lead to multiple organ failure and increased mortality. This response is often heightened following acute surgical management as a result, damage-control orthopaedics (DCO) was born. This allows the patient to be stabilised using external fixation allowing physiology to improve. This systematic review aims to compare DCO against early total care (ETC) (<24hrs intramedullary nailing) in polytraumatised patients with femoral shaft fractures using a diagnosis of acute lung injury (ALI) as the primary outcome measure. Method. A systematic review of MEDLINE, EMBASE, CENTRAL and AMED was carried out to identify all English language studies comparing ETC versus DCO using ALI as the primary outcome measure. Two authors independently screened the studies and performed data extraction. Risk of bias was assessed using the Cochrane risk of bias tool and the Risk-of-Bias Assessment Tool for Non-randomised Studies. Results. Three studies were selected for final inclusion. One multicentre RCT demonstrated a significantly higher odds ratio (6.69) of ALI in the subgroup receiving ETC compared to DCO. The two other studies were retrospective case series with one reporting no significant difference and the second study reporting a significant reduction in ARDS when a DCO approach was used (7.8% vs 15.1%). Meta-analysis was not possible due to heterogeneity. Conclusions. This review supports evidence that in the more unstable patients (Injury Severity Score≥30) treated surgically for femoral shaft fractures in the first 24 hours, DCO may have a protective effect over ETC for ALI. However further studies with large sample sizes are needed to provide clarity on the subject area. Level of Evidence. 1. Ethics. No approval required given the nature of this study (systematic review)

Background. Post-operative acute kidney injury is significant complication following surgery. Patients who develop AKI have an increased risk for progression into chronic kidney disease, end-stage renal failure and increased mortality risk. The patient outcomes following total knee replacement (TKR), who develop AKI has been a topic of interest in recent years as it may have patient and medicolegal implications. Nevertheless, there are no studies looking at the incidence, risk factors and outcomes of AKI following bilateral TKRs at the same sitting. Objectives. To determine the incidence, risk factors and outcomes of post-operative AKI following bilateral TKRs surgery at the same sitting. Methods. This was a retrospective single-centre study performed at the Princess Royal Hospital, which performed a total of 25 BTKR. The incidence, Surgical and patient risk factors were recorded and analysed. Results. The incidence of AKI as defined by NICE guidelines following bilateral TKRs was 20%. 16% (4 patients) had stage 1 and 4% (1 patient) had stage 2 AKI. The mean change in Creatinine between pre- and post-operative blood tests was +19μmol/L. There was a strong significant correlation between CKD and AKI (r=0.75, P<0.05). Furthermore, a moderate correlation was found between higher BMI and pre-operative Charlson index and AKI. AKI did not have an effect on the length of inpatient stay with the mean inpatient length of stay for patients who had an AKI of 10 days compared to 11days for those who did not. All AKIs were resolved within 72 hours. There were no associated mortalities with AKI. Conclusion. The incidence of AKI following bilateral TKR was 20%. Pre-operative chronic kidney disease as well as having a higher BMI were identified as risk factors for developing AKI. Pre-operative CKD optimisation and careful adequate hydration intra-operatively should be considered in these patients. AKI was not associated with an increased length of stay or mortality in our study

Ischaemia-reperfusion injury (IRI) is caused by endothelial and subendothelial damage by neutrophil-derived oxidants. Vitamin C is an antioxidant which attenuates endothelial injury after IRI. Our aim was to evaluate the effect of oral vitamin C in the prevention of IRI in skeletal muscle. We used a model of cross-clamping (3 hours) and reperfusion (1 hour) of the cremaster muscle in rats. Muscle function was assessed electrophysiologically by electrical field stimulation. Infiltration by neutrophils was determined by the activity of tissue myeloperoxidase (MPO) and tissue oedema by the wet-to-dry ratio. Neutrophil respiratory burst activity was measured in control animals and groups pretreated with vitamin C.

IRI significantly decreased muscle function and increased muscle neutrophil MPO activity and muscle oedema. Pretreatment with vitamin C preserved muscle function and reduced tissue oedema and neutrophil infiltration. Neutrophil respiratory burst activity was reduced in the group treated with vitamin C compared with the control group.

We conclude that pretreatment with oral vitamin C protects against acute muscle IRI, possibly by attenuating neutrophil respiratory burst activity.

Abstract. Introduction. Skeletal muscle wasting is an important clinical issue following acute traumatic injury, and can delay recovery and cause permanent functional disability particularly in the elderly. However, the fundamental mechanisms involved in trauma-induced muscle wasting remain poorly defined and therapeutic interventions are limited. Objectives. To characterise local and systemic mediators of skeletal muscle wasting in elderly patients following acute trauma. Methods. Experiments were approved by a local NHS Research Ethics Committee and all participants provided written informed consent. Vastus lateralis biopsies and serum samples were taken from human male and female patients shortly after acute trauma injury in lower limbs (n=6; mean age 78.7±4.4 y) and compared to age-matched controls (n=6; mean age 72.6±6.3 y). Atrogenes and upstream regulators (MuRF1; MAFbx; IL6, TNFα, PGC-1α) mRNA expression was assessed in muscle samples via RT-qPCR. Serum profiling of inflammatory markers (e.g. IL6, TNFα, IL1β) was further performed via multiplex assays. To determine whether systemic factors induced by trauma directly affect muscle phenotype, differentiated primary human myotubes were treated in vitro with serum from controls or trauma patients (pooled; n=3 each) in the final 24 hours of differentiation. Cells were then fixed, stained for myogenin and imaged to determine minimum ferret diameter. Statistical significance was determined at P<0.05. Results. There was an increase in skeletal muscle mRNA expression for E3 ligase MAFbx and inflammatory cytokine IL-6 (4.6 and 21.5-fold respectively; P<0.05) in trauma patients compared to controls. Expression of myogenic determination factor MyoD and regulator of mitochondrial biogenesis PGC-1α was lower in muscle of trauma patients vs controls (0.5 and 0.39-fold respectively; P<0.05). In serum, trauma patients showed increased concentrations of circulating pro-inflammatory cytokines IL-6 (14.5 vs. 0.3 pg/ml; P<0.05) and IL-16 (182.7 vs. 85.2 pg/ml; P<0.05) compared to controls. Primary myotube experiments revealed serum from trauma patients induced atrophy (32% decrease in diameter) compared to control serum-treated cells (P<0.001). Conclusion. Skeletal muscle from patients following acute trauma injury showed greater expression of atrophy and inflammatory markers. Trauma patient serum exhibited higher circulating pro-inflammatory cytokine concentrations. Primary human myotubes treated with serum from trauma patients showed significant atrophy compared to healthy serum-treated controls. We speculate a mechanism(s) acting via circulating factors may contribute to skeletal muscle pathology following acute trauma. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Digital Ventilated Cages (DVC) offer an innovative technology to obtain accurate movement data from a single mouse over time [1]. Thus, they could be used to determine the occurrence of a tendon damage event as well as inform on tissue regeneration [2,3]. Therefore, using the mouse model of tendon experimental damage, in this study it has been tested whether the recovery of tissue microarchitecture and of extracellular matrix (ECM) correlates with the motion data collected through this technology. Mice models were used to induce acute injury in Achilles tendons (ATs), while healthy ones were used as control. During the healing process, the mice were housed in DVC cages (Tecniplast) to monitor animal welfare and to study biomechanics assessing movement activity, an indicator of the recovery of tendon tissue functionality. After 28 days, the AT were harvested and assessed for their histological and immunohistochemical properties to obtain a total histological score (TSH) that was then correlated to the movement data. DVC cages showed the capacity to distinguish activity patterns in groups from the two different conditions. The data collected showed that the mice with access to the mouse wheel had a higher activity as compared to the blocked wheel group, which suggests that the extra movement during tendon healing improved motion ability. The histological results showed a clear difference between different analyzed groups. The bilateral free wheel group showed the best histological recovery, offering the highest TSH score, thus confirming the results of the DVC cages and the correlation between movement activity and structural recovery. Data obtained showed a correlation between TSH and the DVC cages, displaying structural and movement differences between the tested groups. This successful correlation allows the usage of DVC type cages as a non-invasive method to predict tissue regeneration and recovery. Acknowledgements: This research is part of the P4FIT project ESR13, funded by the H2020-ITN-EJD MSCA grant agreement No.955685

In relation to regenerative therapies in osteoarthritis and cartilage repair, mesenchymal stromal cells (MSCs) have immunomodulatory functions and influence macrophage behaviour. Macrophages exist as a spectrum of pro-(M1) and anti-(M2) inflammatory phenotypic subsets. In the context of cartilage repair, we investigated MSC-macrophage crosstalk, including specifically the priming of cartilage cells by macrophages to achieve a regenerative rather than fibrotic outcome. Human monocytes were isolated from blood cones and differentiated towards M1 and M2 macrophages. Monocytes (Mo), M1 and M2 macrophages were cultured directly and indirectly (trans-well system) with human bone marrow derived MSCs. MSCs were added during M1 polarisation and separately to already induced M1 cells. Outcomes (M1/M2 markers and ligands/receptors) were evaluated using RT-qPCR and flow cytometry. Influence on chondrogenesis was assessed by applying M1 and M2 macrophage conditioned media (CM) sequentially to cartilage derived cells (recapitulating an acute injury environment). RT-qPCR was used to evaluate chondrogenic/fibrogenic gene transcription. The ratio of M2 markers (CD206 or CD163) to M1 markers (CD38) increased when MSCs were added to Mo/M1 macrophages, regardless of culture system used (direct or indirect). Pro-inflammatory markers (including TNFβ) decreased. CXCR2 expression by both M1 macrophages and MSCs decreased when MSCs were added to differentiated M1 macrophages in transwell. When adding initially M1 CM (for 12 hours) followed by M2 CM (for 12 hours) sequentially to chondrocytes, there was a significant increase of Aggrecan and Collagen type 2 gene expression and decrease in fibroblastic cell surface markers (PDPN/CD90). Mo/M1 macrophages cultured with MSCs, directly or indirectly, are shifted towards a more M2 phenotype. Indirect culture suggests this effect can occur via soluble signaling mediators. Sequential exposure of M1CM followed by M2CM to chondrocytes resulted in increased chondrogenic and reduced fibrotic gene expression, suggesting that an acute pro-inflammatory stimulus may prime chondrocytes before repair

Abstract. Objectives. In relation to regenerative therapies in osteoarthritis and cartilage repair, mesenchymal stromal cells (MSCs) have immunomodulatory functions and influence macrophage behaviour. Macrophages exist as a spectrum of pro-(M1) and anti-(M2) inflammatory phenotypic subsets. In the context of cartilage repair, we investigated MSC-macrophage crosstalk, including specifically the priming of cartilage cells by macrophages to achieve a regenerative rather than fibrotic outcome. Methods. Human monocytes were isolated from blood cones and differentiated towards M1 and M2 macrophages. Monocytes (Mo), M1 and M2 macrophages were cultured directly and indirectly (trans-well system) with human bone marrow derived MSCs. MSCs were added during M1 polarisation and separately to already induced M1 cells. Outcomes (M1/M2 markers and ligands/receptors) were evaluated using RT-qPCR and flow cytometry. Influence on chondrogenesis was assessed by applying M1 and M2 macrophage conditioned media (CM) sequentially to cartilage derived cells (recapitulating an acute injury environment). RT-qPCR was used to evaluate chondrogenic/fibrogenic gene transcription. Results. The ratio of M2 markers (CD206 or CD163) to M1 markers (CD38) increased when MSCs were added to Mo/M1 macrophages, regardless of culture system used (direct or indirect). Pro-inflammatory markers (including TNFa) decreased. CXCR2 expression by both M1 macrophages and MSCs decreased when MSCs were added to differentiated M1 macrophages in transwell. When adding initially M1 CM (for 12 hours) followed by M2 CM (for 12 hours) sequentially to chondrocytes, there was a significant increase of Aggrecan and Collagen type 2 gene expression and decrease in fibroblastic cell surface markers (PDPN/CD90). Conclusions. Mo/M1 macrophages cultured with MSCs, directly or indirectly, are shifted towards a more M2 phenotype. Indirect culture suggests this effect can occur via soluble signaling mediators. Sequential exposure of M1CM followed by M2CM to chondrocytes resulted in increased chondrogenic and reduced fibrotic gene expression, suggesting that an acute pro-inflammatory stimulus may prime chondrocytes before repair. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Tendon injuries present a major clinical challenge, as they necessitate surgical intervention and are prone to fibrotic progression. Despite advances in physical therapy and surgical technique, tendons fail to return to full native functioning, underlining the need for a biological therapeutic to improve tendon healing. Myofibroblasts are activated fibroblasts that participate in the proliferative and remodeling phases of wound healing, and while these matrix-producing cells are essential for proper healing, they are also linked to fibrotic initiation. A subset of tenocytes has been shown to give rise to the myofibroblast fate, and potentially contribute to fibrotic tendon healing. A viable anti-fibrotic therapy in other tissues has been reprogramming the fibroblast-myofibroblast differentiation route, avoiding a more pro-fibrotic myofibroblast phenotype. Thus, defining the molecular programs that underlie both physiological and pathological tendon healing is critical for the development of potential pharmacologic treatments. Towards that end, we have taken advantage of spatial transcriptomics, using the tenocyte marker Scleraxis as a tool, and have outlined three major spatiotemporally distinct tenocyte differentiation trajectories (synthetic, proliferative, and reactive) following acute tendon injury in mouse FDL. We have further outlined key transcriptional controls that may be manipulated to alter the differentiation process and influence the resulting myofibroblast phenotype, thereby promoting regenerative tendon healing

Poor tendon repair is an unsolved issue in clinical practice, due to complex tendon structure. Tendon stem/progenitor cells (TSPCs) play key roles in homeostasis, regeneration, and inflammation regulation in acute tendon injuries, and rely on TGF-β signaling for recruitment into degenerative tendons. In this study, we aimed to develop an in vitro model for tenogenesis adopting a dynamic culture of a fibrin 3D scaffold, bioengineered with human TSPCs collected from both healthy and tendinopathic surgery explants (Review Board prot./SCCE n.151, 29 October 2020). 3D culture was maintained for 21 days under perfusion provided by a custom-made bioreactor, in a medium supplemented with hTGF-β1 at 20 ng/mL. The data collected suggested that the 3D in vitro model well supported survival of both pathological and healthy cells, and that hTGF-β signaling, coupled to a dynamic environment, promoted differentiation events. However, pathological hTSPCs showed a different expression pattern of tendon-related genes throughout the culture and an impaired balance of pro-inflammatory and anti-inflammatory cytokines, compared to healthy hTSPCs, as indicated by qRT-PCT and immunofluorescence analyses. Additionally, the expression of both tenogenic and cytokine genes in hTSPCs was influenced by hTGF-β1, indicating that the environment assembled was suitable for studying tendon stem cells differentiation. The study offers insights into the use of 3D cultures of hTSPCs as an in vitro model for investigating their behavior during tenogenic events and opens perspectives for following the potential impact on resident stem cells during regeneration and healing events

Abstract. Objectives. Routine blood test following total shoulder arthroplasty (TSA) cost the NHS more than £72000 in 2018 without definite evidence of their impact on patients’ management or outcomes. This study aimed to ascertain if routine laboratory tests are a necessity post TSA or can be implemented on a per-patient. Methods. A retrospective review of the electronic records completed for 251 patients underwent TSA over 6 years. 193 patients were eligible for analysis. Primary outcomes were interventions to the abnormal postoperative blood tests. Secondary outcomes were the length of stay (LOS), and readmission within 30 days and 90 days. Results. 193 patients underwent 216 TSAs; 72 % were females and 18% males. The mean age was 78 ± 7.2 years. Completed procedures included 134 reverse, 64 anatomical and 18 revision TSAs. 136 patients (63%) had an abnormal postoperative blood test, however, only 8 (3.7%) required intervention. The average postoperative haemoglobin (Hb) drop was 19 g/L with 94 patients (43.5%) having Hb <109g/L. 4 patients (1.8%) dropped Hb < 80g/L; only 2 patients (0.9%) were symptomatic and received RBC transfusion . 6 patients (2.8%) developed acute kidney injury and treated by IV fluids. The mean LOS was 3.2 ± 2.9 days .5 patients (2.3%) were readmitted within 30 days and 6 patients (2.8%) within 90 days. Univariate analysis showed association only between abnormal Creatinine and LOS (p<0.05) and of these patients, all had abnormal preoperative Creatinine baseline. No statistical correlation detected between age (p=0.287), postoperative Hb (p=0.230) and LOS nor readmission at 30 or 90 days. Conclusions. Routine postoperative blood tests are not required as they have not shown to produce a meaningful clinical impact in this cohort of patients nor on the re-admission rate, causing unnecessary costs. We recommend assessing each patient and request for investigations in a coherent and justified manner. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Background. The current average tariff of a total knee replacement (TKR) is £5500. The approximate cost of each knee prosthesis is £2500. Therefore, length of patient stay (LOS) and the cost of patient rehabilitation influence the total costs significantly. Previous studies have shown a mean LOS of between 5 and 9.4 days for patients undergoing primary unilateral TKR but none looked at the factors influencing length of stay following bilateral primary total knee replacements (BTKR) at the same sitting. Objectives. To identify significant factors that influence the LOS following BTKR at the same sitting in a single centre in the UK. Methods. This was a retrospective single-centre study performed at the Princess Royal Hospital which performed a total of 25 BTKR. Surgical and patient factors that may influence LOS were recorded and analysed. Results. The mean LOS was 10 days with a median of 9 days. 64% were discharged within 10 days. Those staying longer were classified as long stayers. Being a female (0.65, p< 0.05), having a higher Charlson index (0.68, p< 0.05) and having a post-operative blood transfusion (0.59, p< 0.05) were the only significant factors that influenced LOS. Post-operative acute kidney injury (AKI), underlying diagnosis such as rheumatoid arthritis, BMI, age, worse pre-operative oxford knee scores and type of implant did not influence LOS. Conclusion. Factors influencing LOS following BTKR shown in our study seems to be the same as those influencing unilateral TKRs as identified in the literature. This should be taken into consideration when comparing unilateral versus bilateral TKR results as well as when planning a local arthroplasty service

Introduction. Postoperative total shoulder arthroplasty (TSA) blood tests cost the National Health Service in the UK more than £72000 annually without definite evidence of their impact on outcomes. This study aimed to ascertain if these blood tests can be implemented on a per-patient basis. Methods. A retrospective review of one centre TSA patients over 6 years. Primary outcomes were interventions to abnormal postoperative blood tests. Secondary outcomes were the length of stay (LOS), and readmission within 30 and 90 days. Results. 193 patients underwent 216 TSAs; 72 % were females and 18% males. The mean age was 78 ± 7.2 years. Completed procedures included 134 reverse, 64 anatomical and 18 revision TSAs. 136 patients (63%) had an abnormal postoperative blood test, however, only 8 (3.7%) required intervention. The average postoperative Hb drop was 19 g/L with 94 patients (43.5%) having Hb <109g/L. 4 patients (1.8%) dropped Hb < 80g/L; only 2 (0.9%) were symptomatic and received RBC transfusion. 6 patients (2.8%) developed acute kidney injury and treated by IV fluids. The mean LOS was 3.2 ± 2.9 days .5 patients (2.3%) were readmitted within 30 days and 6 patients (2.8%) within 90 days. Univariate analysis showed association only between abnormal Creatinine and LOS (p<0.05) and of these patients, all had abnormal preoperative Creatinine baseline. No statistical correlation detected between age (p=0.287), postoperative Hb (p=0.230) and LOS nor readmission at 30 or 90 days. Conclusions. Routine postoperative blood tests are not required as no detected meaningful clinical impact and should be requested on an individual justified basis

Introduction. Acute kidney injury is a recognised post-operative complication in primary joint replacement. Recently it has been demonstrated that antibiotic regimen can significantly impact on the proportion of patients who develop acute kidney impairment post-operatively. Within our unit an increased rate of acute kidney injury had been noted post-operatively over the last 5 years. This increase followed the introduction of a rapid recovery protocol for arthroplasty patients. Our aim was determine whether we could identify a causative factor or those who were at increased risk of post-operative renal impairment. Methods. Data were collected for 413 patients initially retrospectively but continued prospectively. Univariable and multivariable analysis was performed to determine any causative factors. The primary increase was 150% increase in baseline creatinine, but as some authors recognise an increase in 125% this was also analysed. Results. Within the 12 month period studied 23.3% of patients developed acute kidney injury, with an increase of 125% of their baseline creatinine. 8.23% of patients developed an increase of 150% in their creatinine levels. Age, previous renal failure and the pre-operative use of an ACE inhibitor were found to be statistically higher in the renal failure group. The uni-variable analysis also demonstrated that patients who received a small volume of post-operative intravenous fluids had a lower rate of renal failure than those who received no fluids (10% vs. 23%; p = 0.04). The multivariable regression analysis demonstrated that age was the only statistically significant positive predictive factor in developing renal failure. Antibiotic regimen had no effect. Discussion. Renal impairment has significant impact on patient morbidity and post-operative management. It increases the length of stay, and may potentially require more invasive therapy. We have demonstrated that the identified risk factors are non-modifiable but that a gentamicin and teicoplanin regimen was not an implicated causative factor

Purpose. Collagen-rich structures of the knee are prone to damage through acute injury or chronic “wear and tear”. Collagen becomes more disorganised in degenerative tissue e.g. osteoarthritis. An alignment index (AI) used to analyse orientation distribution of collagen-rich structures is presented. Method. A healthy caprine knee was scanned in a Siemens Verio 3T Scanner. The caprine knee was rotated and scanned in nine directions to the main magnetic field B. 0. A 3D PD SPACE sequence with isotropic 1×1×1mm voxels (TR1300ms, TE13ms, FOV256mm,) was optimised to allow for a greater angle-sensitive contrast. For each collagen-rich voxel the orientation vector is computed using Szeverenyi and Bydder's method. Each orientation vector reflects the net effect of all the fibres comprised within a voxel. The assembly of all unit vectors represents the fibre orientation map. Alignment Index (AI) in any direction is defined as a ratio of the fraction of orientations within 20° (solid angle) centred in that direction to the same fraction in a random (flat) case. In addition, AI is normalised in such a way that AI=0 indicates isotropic collagen alignment. Increasing AI values indicate increasingly aligned structures: AI=1 indicates that all collagen fibres are orientated within the cone of 20° centred at the selected direction. AI = (nM - nRnd)/(nTotal - nRnd) if nM >= nRnd. AI = 0 if nM < nRnd. Where:. nM is a number of reconstructed orientations that are within a cone of 20° centred in selected direction. nRnd is a number of random orientations within a cone of 20° around selected direction. nTotal is a number of collagen reach voxels. By computing AI for a regular gridded orientation space we are able to visualise change of AI on a hemisphere facilitating understanding of the collagen fibre orientation distribution. Results. The patella tendon had an AI=0.6453. The Anterior Cruciate Ligament (ACL) had an AI=0.2732. The meniscus had an AI=0.1847. Discussion. The most aligned knee structure is the patella tendon where the collagen fibres align with the skeleton to transmit forces through bones and muscles. This structure had the AI closest to 1. The ACL had the second highest AI and is composed of two fibre bundles aligned diagonally across the knee. The meniscus acts as a shock absorber and is made up of vertical, radial and circumferential fibres which disperse forces more equally. The complexity of the meniscal structure resulted in the lowest AI. To date, this technique has only been performed with healthy tissue; the AI may become closer to zero if there is damage disrupting the collagen fibre alignment. The AI can further our understanding of collagen orientation distribution and could be used as a quantitative, non-invasive measure of structural health

Metabolic disorders are frequently associated with tendon degeneration and impaired healing after acute injury. However, the underlying cellular and molecular mechanisms remain largely unclear. We have previously shown that human and rat tendon cells responde to glucose stimulation in vitro by secretion of insulin. Therefore, we now hypothesize that nutritional glucose uptake affects tendon healing in a rat model. In female rats (n=30/group), unilateral full-thickness Achilles tendon defects were created. Immediately after surgery animals were either fed a glucose rich- or a control diet for up to 4 weeks. Gait analysis (Catwalk, Noldus) was performed at three time points. In addition, tendon thickness measurements, biomechanical testing and immunohistochemical analysis were conducted. Subsequently, gene expression analysis, comparing cDNA pools (n=5) prepared from repair tissues of both groups was performed. The repair tissues of the high glucose group were significantly thicker compared to the control group (p<0.001). The intermediate toe spread, an indicator of pain, were significantly improved in the high glucose group one and two weeks post surgery. Biomechanical analysis revealed that the repair tissues of the high glucose group were significantly stiffer (p<0.05) compared to the control group, no significant difference was detected for maximum tensile load…. The proportion of Ki67+ cells in the repair tissue was 3.3% in the control diet group and 9,8% in the high glucose group, indicating increased cell proliferation (p<0.001). Finally, gene expression analysis revealed the chondrogenic marker genes Collagen II, Aggrecan, COMP and SOX9 to be upregulated and genes involved in lipid metabolism like PPARgamma and Fabp2 to be downregulated in the glucose diet group. Here we show fort he first time that a high-glucose diet affects gait pattern and tendon biomechanics, influences tendon thickness and cell proliferation. Gene expression analysis reveals a regulation of chondrogenic as well as adipogenic marker genes. The molecular mechanisms underlying these effects on cells and extracellular matrix are currently under investigation, potentially revealing targets for developing a dietary intervention scheme to support tendon regeneration after trauma or tendon disease

Muscle and tendon have an adaptive, symbiotic biomechanical relationship that is drastically altered following acute tendon injury. Such injuries, like Achilles tendon rupture (ATR), do not only lead to impairments in the resultant tendinous tissue, but also to irrecoverable atrophy in the connected muscle in series. As a result, a new relationship between muscle and tendon is established after ATR, leading to lasting functional deficits in the lower limb. It remains unclear how these develop, particularly since this imbalance may be influenced by the dependent relationship of the two tissues to each other. A further confounding factor is that tendon and muscle tissues adapt on different time scales in response to mechanical loading, such as those introduced during rehabilitation. Thus, it is warranted to perform assessments not only of the overall muscle-tendon unit, but also its constituent tissues. This presentation will discuss findings from both short-term and long-term follow-ups of ATR patients, with a focus on the recovery of gait and changes in the muscle-tendon unit tissues following ATR repair. Both the influence of the rehabilitation process and suggestions for future research directions will be additionally presented

Locking plate fixation in proximal humeral fractures has demonstrated good results tempered by a significant rate of loss of fixation. Reported rates of failure are typically around 10% of cases but can be 20% or higher. In addition large series are often made up of a diverse patient population, so we have chosen to focus solely on patients confirmed to have significantly reduced BMD who can be considered a subset at high risk of fixation failure. Twenty-three patients (5 male, 18 female) with a proximal humeral fracture treated by locking plate fixation were confirmed on DEXA scanning to be osteopaenic (17), osteoporotic (4) or severely osteoporotic (2). Patients early in the series were reviewed retrospectively and recalled for an updated assessment where appropriate, and the remainder were followed prospectively. The average age was 66 years (range 49 to 82). Follow up was for an average of nine months following surgery (range 2 and a half to 28 months). 17 patients underwent surgery for acute injuries and 6 for established surgical neck non-unions. Seven injuries were 2-part fractures, 12 3-part, 3 were 4-part and one a 2-part surgical neck non-union.1 plate failed due to complete loss of fixation within 2 months in a patient with severe osteoporosis and was treated with removal of metalwork. This was the only injury that failed to unite. Avascular necrosis occurred in three patients with two revised to a hemiarthroplasty. 1 patient had ongoing pain and underwent removal of the plate. Our series demonstrated that locking plate fixation of proximal humeral fractures is associated with a low rate of fixation failure and satisfactory outcomes in patients with significantly reduced bone mineral density

There is a growing socio-economic need (i.e. “ageing society”) for effective and reproducible strategies to repair musculoskeletal tissue. In particular, acute tendon injury and chronic tendinopathies remain clinically challenging and novel treatment modalities are urgently needed. Tendons resemble a connective tissue rich in highly organized collagen fibers, displaying a remarkably high tensile strength. However, partly due to the low number of cells and their more or less avascular nature tendons heal relatively slowly. Ultimately, tendon regeneration encompasses the full restoration of the biological, biochemical and biomechanical properties, which are often impaired by endogenous healing cascades. Usually, a connective scar tissue forms at the injury site and the replaced tissue does not function adequately at high strain levels, increasing the chance of re-rupture. Despite significant advancements in tissue regeneration and engineering strategies, the clinical impact for the regeneration of tendon remains limited. For the development of novel methods to repair tendons we need to pin down the molecular and cellular mechanisms amenable to modulate endogenous (or exogenous) cell behaviour towards functional tissue regeneration. By comparing the gene expression profile of Achilles tendon tissue harvested from young-mature and old mice we demonstrate profound changes in the expression of ECM-related proteins and a previously unknown role of Secreted protein acidic and rich in cysteine (Sparc; also known as BM-40 or osteonectin) in tendons. Sparc levels in tendons are critical for proper collagen fibril maturation and its age-related decrease, together with a change in ECM properties potentially drives adipogenic differentiation of tendon stem and progenitor cells (TDSPCs) and consequently lipid accretion in tendons. Generally, the fate of stem/ progenitor cells is largely determined by stimuli from the stem cell niche. In tendons, we describe a novel cellular barrier, most likely preventing the leakage of blood-borne products into the tendon proper. We propose that this “blood-tendon barrier” is part of the stem cell niche in tendons controlling TDSCP fate, preventing erroneous differentiation. By investigating the developmental programs driving tendon tissue formation and on the other hand the mechanisms contributing to the senescence of tendons, ultimately resulting in decreased quality of tendons in the elderly, novel targets for clinical intervention potentially can be discovered