Intra-Discal Vacuum Phenomenon (IDVP) represents an intradiscal nitrogen gas accumulation where a cavity opens in a supine position, lowering intra-discal pressure and generating a bubble. IDVP has been observed in up to 20% of elderly patients and reported in almost 50% of chronic LBP patients. With a highly accurate detection on CT, its significance lacks clarity and consideration within normative data. IDVP occurs with patterns of lumbar and/or lumbopelvic morphology and associated diagnoses. Over-60s population based sample of 2020 unrelated CT abdomen scans without acute spinal presentations, with sagittal reconstructions, inclusive of T12 to femoral heads, were analyzed for IDVP and pelvic incidence (PI). Subjects with diagnostic morphological associations of the lumbar spine, including previous fracture, autofusion, transitional vertebra and listhesis, were selected out and analyzed separately. Subjects were then equally grouped into low, medium and high PI. Prevalence of lumbar spine IDVP is 41.3%. 125 cases were excluded. 1603 subjects yielded 663 IDVP. This was increased in severity towards the lumbosacral junction (L1L2 9.4%, L2L3 10.9%, L3L4 13.7%, L4L5 19.9%, L5S1 28.5%) and those with low PI, while distribution was more even with high PI. 292 had positive diagnostic associations, which were more likely to occur at the level of isthmic spondylolisthesis, adjacent to a previous fracture or suprajacent to lumbosacral transitional vertebra (p<0.05). This study has identified normative values for prevalence and severity of IDVP in a normal aging population. Morphological patterns that influence the pattern of IVDP such as pelvic incidence and diagnostic associations provide novel insights to the function of the aging spine

Proximal femur fractures are common in the elderly population. The aim of this study was to determine the relationship between fracture type and proximal femoral geometric parameters. We retrospectively studied the electronic medical records of 85 elderly patients over 60 years of age who were admitted to the orthopedic department with hip fractures between January 2016 and January 2018 in a training and research hospital in Turkey. Age, fracture site, gender, implant type and proximal femoral geometry parameters (neck shaft angle [NSA], center edge angle [CEA], femoral head diameter [FHD], femoral neck diameter [FND], femoral neck axial length [FNAL], hip axial length [HAL], and femoral shaft diameter [FSD]) were recorded. Patients with femoral neck fractures and femur intertrochanteric fractures were divided into two groups. The relationship between proximal femoral geometric parameters and fracture types was examined. SPSS 25.0 (IBM Corparation, Armonk, New York, United States) program was used to analyze the variables. Independent samples t test was used to compare the fracture types according to NSA, FHD, FND and FSD variables. A statistically significant difference was found in FSD (p=0,002) and age (p=0,019). FSD and age were found to be greater in intertrochanteric fractures than neck fractures. Gender, site, CEA, FNAL, HAL, NSA, FHD and FND parametres were not significantly different. In the literature, it is seen that different results have been reached in different studies. In a study conducted in the Chinese population, a significant difference was found between the two groups in NSA, CEA and FNAL measurements. In a study conducted in the Korean population, a significant difference was found only in NSA measurements. The FSD is generally associated with bone mineral densitometry in the literature and has been shown to be a risk factor for fracture formation. However, a study showing that there is a relationship between FSD and fracture type is not available in the literature. In this study; FSD was found to be higher in intertrochanteric fractures (p = 0.002). However, for the clinical significance of this difference, we think that larger patient series and biomechanical studies are needed

Achilles tendinopathy is classically defined as a tendinosis devoid of an inflammatory cell population. However, recent literature suggests inflammation as a mediator in the pathogenesis. These finding were mainly based on semi-quantative immunohistochemistry. We therefore used flow cytometry to obatain a more accurate identification and quantification of the different cell types involved. Thirty-two samples were obtained from twelve patients with chronic tendinopathic lesions undergoing Achilles tendon surgery. Samples obtained from three patients with hemiplegia requiring surgical release due to spastic Achilles tendons served as control. We used two panels to identify the myeloid and lymphoid population targeting the following markers: CD45, CD3, CD8, CD4, CD19, CD11b, CD56, CD14, CD16, Vα7.2, 6b11, CD161, TCRγδ. To assess the presence of fibroblasts CD90 was targeted. The mean count of CD45+ hematopoietic cells in the tendinopathic samples was significantly higher than in the control samples, respectively 13.27% and 3.24% of the total cell count (P<0.001). The mean fraction of CD3+ cells present in the complete cell population was significantly higher in pathological samples than in control samples, respectively 1.70% and 0.37% (P<0.05). Presence of CD19+ B cells was not reported. The mean fraction of γδ T cells was significantly higher in tendinopathic samples compared to blood samples of the same patient and consisted of 12.9% and 5.8% γδ T cells respectively (P<0.05). These findings support an inflammatory cell infiltration in midportion Achilles tendinopathy that show similarities to enthesitis in SpA. This implies a potential target to investigate in novel treatment modalities

Acetabular morphology and orientation differs from ethnic group to another. Thus, investigating the natural history of the parameters that are used to assess both was a matter of essence. Nevertheless, clarification the picture of normal value in our society was the main aim of this study. However, Acetabular head index (AHI) and center edge angle (CEA) were the most sensitive indicative parameters for acetabular dysplasia. Hence, they were the main variables used in evaluation of acetabular development.

A cross-sectional retrospective study that had been done in a tertiary center. Computed tomography abdomen scouts’ radiographs of non-orthopedics patients were included. They had no history of pelvic or hips’ related symptoms or fractures in femur or pelvis. Images’ reports were reviewed to exclude those with tumors in the femur or pelvic bones.

A total of 81 patients was included with 51% of them were males. The mean of age was 10.38± 3.96. CEA was measured using Wiberg technique, means of CEA were 33.71±6.53 and 36.50±7.39 for males and females, respectively. Nonetheless, AHI means were 83.81±6.10 and 84.66±4.17 for males and females, respectively. On the other hand, CEA was increasing by a factor 0.26 for each year (3-18, range). In addition, positive significant correlation was detected between CEA and age as found by linear regression r 2 0.460 (f(df1,79) =21.232, P ≤0.0001). Also, Body mass index (BMI) was positively correlated with CEA r 0.410, P 0.004).

This study shows that obesity and aging are linked to increased CEA. Each ethnic group has its own normal values that must be studied to avoid premature diagnosis.

This study was proposed to evaluate the efficacy of fibrin clot augmentation in meniscal tear using inside-out meniscal repair.

A total of 35 patients with meniscus tears were operated on with inside-out meniscus repair and fibrin clot augmentation. Patients were evaluated preoperatively and postoperatively with clinical criteria, Lysholm knee scoring system, and MRI.

Out of the total 35 cases, 5 cases were lost to follow up. Clinical improvement was observed in 29 out of 30 patients (96.6%). The mean Lysholm score improved significantly from 67.63 ± 6.55 points preoperatively to 92.0 ± 2.9 points postoperatively (P < 0.05) in 2 years follow-up. Follow-up MRI in all patients revealed complete healing except in 1 case where the patient presented with recurrence of symptoms such as pain and locking which resolved with partial meniscectomy. Paraesthesia in the anterior part of the knee was observed in 2 cases. (6.6%).

We conclude that fibrin clot augmentation is a good cost-effective modality of treatment for repairable meniscus tears to preserve the meniscus and decrease the point contact pressure on the condyles which may prevent the early occurrence of osteoarthritis.

Objective. Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) bring relief of pain and functional disability to patients with end stage osteoarthritis, however the literature on their impact on patients’ level of physical activity (PA) is scarce. Methods. Cross-sectional study, performed in 2012, in 515 patients who underwent THA/TKA surgery in 2010–2011 and a random sample of persons aged >40 years from the Dutch general population participating in a national survey in the same period. PA in minutes per week (min/week) and adherence to the Dutch recommendation for health enhancing PA was measured by means of the Short QUestionnaire to ASsess Health enhancing PA (SQUASH) Additional assessments included socio-demographic characteristics, the presence of comorbidities, BMI and Short Form-12. Multivariable linear (total min/week) and logistic regression analyses (meeting PA recommendation), adjusting for confounders, were performed for THA and TKA separately. Results. 258 THA patients (64% female, mean age 70.0 (SD9.2)), 221 TKA patients (67% female, mean age 70.2 (SD8.9)) and 4373 persons from the general population sample (52% female, age 59.0 (SD12.0)) were included. In both regression analyses, the presence of joint arthroplasty was statistically significantly associated with more total min/week spent on PA (THA 7.0% increase, 95%-CI (2.0%–12.6%); TKA 7.4% increase, 95%-CI (1.6%–13.4%)) and a higher chance of adherence with PA recommendations (THA OR 1.90, 95%-CI (1.12–3.03); TKA OR 1.94, 95%-CI (1.19–3.15)). Conclusion. 6-18 months after surgery, THA/TKA patients were more physically active than a random sample of persons >40 years from the Dutch general population

Meniscus is mainly composed of three different cell types; chondrocytes(Ch) situate in the superficial zone, whereas fibroblast-like cells locate in the peripheral region having long cell extensions in contact with different parts of the matrix, fibrochondrocytes(FC), is from the inner part of the meniscus and show a clear cell associated matrix. The aim of this study is to develop meniscus cell population using with mesenchymal stem cells (MSCs). For this purpose, MSCs were isolated from rabbit bone marrow and verified by flow cytometry analyses using cell surface markers (CD73APC, CD90FITC, CD34PE, CD45PE/Cy5.5). The results indicate that CD73 and CD90-positive cells were 92.8%, and CD 45 and CD 34-negative cells were 52.4%. Differentiation potential of MSCs were also evaluated by differentiating into Ch, osteoblasts (Ob), adipocytes (Ad), fibroblasts (Fb). Histology stainings showed that differentiated Ch can produce proteoglycans, Ob have mineralization property, Fb have spindle shape and Ad have oil drops morphology. Afterwards Fb, Ch and undifferentiated MSCs (for formation of the FC) were seeded in same plate in cocktail medium and Fb, Ch, seeded individually, were used as control group. Proliferation activity of the cells was analyzed by XTT assay at 3. th. ,7. th. and14. th. days. In addition, cells were analyzed by flow cytometry with identical surface markers at 3. th. ,7. th. and14. th. days. Results show that cell cocktail have the greatest proliferation ability with a greater speed than the individual Ch or Fb cultures. In addition, FC formation was identified by histological staining. In conclusion, meniscus specific cell population has been successfully generated from the cell cocktail containing rabbit MSCs

Background. Despite an ageing population and a rise in the number of joint replacements being performed, the mean age of patients undergoing surgery remains static. One explanation for this is continued concern over the risks of performing surgery on the very elderly. We aim to investigate the outcome of Total Knee Replacement (TKR) in a nonagenarian population. Methods. The Elective Orthopaedic Centre, Epsom has an established patient reported outcome measures (PROMs) programme into which all patients are routinely enrolled. We retrospectively reviewed our data set for a cohort of nonagenarians undergoing primary TKR, between April 2008 and October 2011. Post-operative complications, mortality rates and functional outcomes were compared to those of a time matched 70–79 year old cohort. Only patients with a primary diagnosis of osteoarthritis were included whereas an exclusion criterion consisted of patients undergoing revision surgery, simultaneous bilateral replacements or conversion from a Unicompartmental Knee replacement. Results. We identified 31 nonagenarian patients, with a mean age of 91.0 (90–96) and the control group consisted of 36 patients, with a mean age of 74.5 (70–79). Following a TKR, the nonagenarian cohort achieved a lower mean Oxford Knee Score (OKS) at 1 year (31.7+/−9.5) (p=0.15), but no difference existed by 2 years (p=0.157), and a mean outcome satisfaction of 85.2% (+/− 22.75) at 1 year, which was similar to the younger group. The nonagenarians had a greater risk of requiring a blood transfusion following a TKR (p=0.0373; CI 1.08 to 16.65), and a longer length of stay than their younger counterparts (p=0.001). Mortality rates were higher in the nonagenarian cohort, but these were in keeping with the life expectancy projections identified by the Office for National Statistics. Conclusion. In conclusion, we identified that over a 2 year period, nonagenarians achieved the same functional outcome and satisfaction rates following a TKR as 70–79 year olds. Level of Evidence IV

To investigate changes in quadriceps and hamstrings muscle groups during sustained isokinetic knee flexion and extension.

125 paediatric participants (45 males and 80 females, mean age 14.2 years) were divided into two groups: participants with a confirmed ACL tear (ACLi, n = 64), and puberty- and activity-level matched control participants with no prior history of knee injuries (CON, n = 61). Participants completed a series of 44 repetitions of isokinetic knee flexion and extension at 90 deg/ sec using a Biodex dynamometer (Biodex Medical Systems Inc, Shirley, New York). Surface EMG sensors (Delsys Incorporated, Natick, MA) simultaneously recorded the quadriceps and hamstring activations. Muscle function was assessed as the change in quadriceps activation and extension torque were calculated using the percent difference between the mean of the first five trials, and the mean of the last five trials.

ACLi participants had significantly higher percent change in quadriceps activation for both healthy and injured legs, in comparison to CON dominant leg. As such, the healthy leg of the ACLi participants is activating significantly more than their health matched controls, while also demonstrating reduced muscular endurance (less torque in later repetitions). Therefore, we conclude that the non-injured limb of the ACLi participant is not performing as a healthy limb. Since return to activity clearance following ACLi implies return to sport against age- and activity matched opponents, clearing young athletes based on the non-injured contralateral limb may put them at greater risk of reinjury.

To investigate differences in the drop vertical jump height in female adolescents with an ACL injury and healthy controls and the contribution of each limb in this task. Forty female adolescents with an ACL injury (ACLi, 15.2 ± 1.4 yrs, 164.6 ± 6.0 cm, 63.1 ± 10.0 kg) and thirty-nine uninjured (CON, 13.2 ± 1.7 yrs, 161.7 ± 8.0 cm, 50.6 ± 11.0 kg) were included in this study. A 10-camera infrared motion analysis system (Vicon, Nexus, Oxford, UK) tracked pelvis, thigh, shank, and foot kinematics at 200Hz, while the participants performed 3 trials of double-legged drop vertical jumps (DVJ) on two force plates (Bertec Corp., Columbus, USA) sampled at 2000Hz.The maximum jump height normalised by dominant leg length was compared between groups using independent samples t-test. The maximum vertical ground reaction force (GRFz) and sagittal ankle, knee and hip velocities before take-off were compared between limbs in both groups, using paired samples t-test. The normalised jump height was 11% lower in the ACLi than in the CON (MD=0.04 cm, p=0.020). In the ACLi, the maximum GRFz (MD=46.17N) and the maximum velocities of ankle plantar flexion (MD=79.83°/s), knee extension (MD=85.80°/s), and hip extension (MD=36.08°/s) were greater in the non-injured limb, compared to the injured limb. No differences between limbs were found in the CON.

ACL injured female adolescents jump lower than the healthy controls and have greater contribution of their non-injured limb, compared to their injured limb, in the DVJ task. Clinicians should investigate differences in the contribution between limbs during double-legged drop vertical jump when assessing patients with an ACL injury, as this could help identify asymmetries, and potentially improve treatment, criteria used to clear athletes to sport, and re-injury prevention.

Summary Statement. Pincer deformities are involved in the genesis of femoro-acetabular impingement (FAI). Radiographic patterns suggestive of pincer deformities are common among general population. Prevalence of the pincer deformities among general population may be overestimated if only plain radiographs are considered. Background. Pincer deformities (coxa profunda, protrusio acetabuli, global retroversion, isolated cranial over-coverage) have been advocated as a cause of femoro-acetabular impingement (FAI) and early hip osteoarthritis (OA). Different radiographic patterns may advocate the presence of a pincer deformity. The prevalence of these radiographic patterns among general adult population, as their role in early hip OA, is poorly defined. Methods. From a database of 40.351 pelvic radiograms and CT collected at our institution between 2005 and 2010, we selected 118 caucasian individuals (56 females, 62 males), aged between 15 and 60 years, who underwent both plain radiographs and CT of the pelvis. A series of exclusion criteria were strictly applied to achieve a sample of adult general population as more representative as possible. In particular patients with presence of any disease involving hip joint, including: advanced hip OA (grade II or III of Tonnis scale), head necrosis, fractures, heterotopic ossifications, bone and soft tissue tumors, rheumatic pathologies, classic hip dysplasia with lateral center-edge angle (L-CEA) less than 20°, clinical diagnosis of FAI or hip pain, were excluded from the present study. We also excluded patients in which open growth plates, osteopenia, hardware or evidence of prior surgery were present. Radiographs were investigated for pelvic tilt, signs of retroversion, lateral center-edge angle (L-CEA), presence of coxa profunda or protrusio acetabuli. EAV was measured on CT scans at the equatorial plane of the acetabulum passing by the 3 o'clock position, while CAV was calculated at a more cranial level corresponding to the 1 o'clock position EAV and CAV were obtained in the axial plane by measuring the angle made by a line connecting the anterior and posterior rims of the acetabulum and a line perpendicular to the line connecting the ischial spines. A new parameter, Acetabular torsion (AT), has been introduced in order to discriminate between global retroversion and isolated cranial over-coverage. AT was defined as the difference between EAV and CAV. Cam deformity was assessed by calculating the alpha angle on the femoral side; an alpha angle > 55° was considered abnormal and suggestive of cam deformity. Radiological signs of chondrolabral degeneration were noticed. Results. Mean EAV and mean CAV were higher in females, mean AA was higher in males. L-CEA, EAV and CAV increased with age. Mean AT was 8.8±6.3. AT was inversely related to CAV (r=−0.799; p<0.0005) but independent from EAV (r=−0.076; p=0.244). EAV≤10.2° was defined as the marker of global retroversion, while AT≥21.2° was defined as the marker of isolated cranial over-coverage. Overall prevalence of pincer deformities was 21.6% (> females; p=0.02). Early OA changes were related to age (p<0.0005) and AA (p<0.0005), but not to pincer deformities (p=0.96). Radiological signs of retroversion showed good or excellent negative predictability but poor positive predictability. Conclusions. Radiographic patterns of pincer deformities are common among general population. Relationship with radiological signs of chondrolabral degeneration is poor. CT allows to discriminate between global retroversion and isolated cranial over-coverage. Prevalence of the pincer deformities among general population may be overestimated if only plain radiographs are considered

Objectives

To assess the sensitivity and specificity of self-reported osteoporosis compared with dual energy X-ray absorptiometry (DXA) defined osteoporosis, and to describe medication use among participants with the condition.

Background and purpose. Over the past decade, it has become apparent that more often than not musculoskeletal pain occurs in more than one site in an individual, and traditional approaches, where pain has been studied as a narrow site-specific problem, are often not feasible. The overall aim of this study is to describe clusters of pain using a large population-based sample. This presentation will focus specifically on musculoskeletal co-complaints in back pain sufferers. Methods and results. The Danish National Institute of Public Health has since 1987 conducted national representative health interview surveys of the adult Danish population some of which have included questions on musculoskeletal complaints. We used latent class analysis to identify latent classes of musculoskeletal complaints that occurred alongside a primary complaint of back pain. In addition, probabilities that specific sites occurred as co-complaints were determined. Three latent classes were identified and they exhibited quite different patterns of musculoskeletal co-complaints. The most commonly occurring class had a low probability of any co-complaints, the second most commonly occurring class had a high probability of pain in the neck, shoulders and mid-back, while the least commonly occurring class had very high probabilities of pain at all other body sites. Conclusions. Latent class analysis can be used to identify distinctly different groups of pain patterns in persons primarily complaining of back pain. The three groups identified likely have very different prognoses. Conflicts of Interest. None. Source of Funding. None. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting

To determine the risk of total knee replacement (TKR) for primary osteoarthritis (OA) associated with overweight/obesity in the Australian population. This population-based study analyzed 191,723 cases of TKR collected by the Australian Orthopaedic Association National Joint Registry and population data from the Australian Bureau of Statistics. The time-trend change in incidence of TKR relating to BMI was assessed between 2015-2018. The influence of obesity on the incidence of TKR in different age and gender groups was determined. The population attributable fraction (PAF) was then calculated to estimate the effect of obesity reduction on TKR incidence. The greatest increase in incidence of TKR was seen in patients from obese class III. The incidence rate ratio for having a TKR for obesity class III was 28.683 at those aged 18-54 years but was 2.029 at those aged >75 years. Females in obesity class III were 1.7 times more likely to undergo TKR compared to similarly classified males. The PAFs of TKR associated with overweight or obesity was 35%, estimating 12,156 cases of TKR attributable to obesity in 2018. The proportion of TKRs could be reduced by 20% if overweight and obese population move down one category. Obesity has resulted in a significant increase in the incidence of TKR in the youngest population in Australia. The impact of obesity is greatest in the young and the female population. Effective strategies to reduce the national obese population could potentially reduce 35% of the TKR, with over 10,000 cases being avoided

Energy storing tendons such as the human Achilles and equine superficial digital flexor tendon (SDFT) are prone to age-related injury. Tendons have poor healing capacity and a lack of effective treatments can lead to ongoing pain, reduced function and re-injury. It is therefore important to identify the mechanisms underpinning age-related tendinous changes in order to develop more effective treatments. Our recent single cell sequencing data has shown that tendon cell populations have extensive heterogeneity and cells housed in the tendon interfascicular matrix (IFM) are preferentially affected by ageing. There is, however, a lack of established surface markers for cell populations in tendon, limiting the capacity to isolate distinct cell populations and study their contribution to age-related tendon degeneration. Here, we investigate the presence of the cell surface proteins MET proto-oncogene (MET), integrin subunit alpha 10 (ITGA10), fibroblast activation protein alpha (FAP) and platelet derived growth factor receptor alpha (PDGFRA) in the equine SDFT cell populations and their co-localisation with known markers. Using Western blot we validated the specificity of selected antibodies in equine tissue before performing immunohistochemistry to establish the location of the respective proteins in the SDFT. We subsequently used double labelling immunofluorescence with the established mural cell marker desmin (DES) to distinguish between tenocyte and mural cell populations. In situ, MET, ITGA10, and FAP presence was found in cells throughout the tendon whereas PDGFRA was present in cells within the IFM. Double labelling immunofluorescence with the mural cell marker DES showed lack of co-localisation between PDGFRA and DES suggesting PDGFRA is labelling an IFM cell population distinct from those associated with blood vessels. PDGFRA is a promising target for the specific cell sorting of IFM-localised tenocytes, enabling their isolation and subsequent characterisation. Acknowledgments: The authors acknowledge the Biotechnology and Biological Sciences Research Council (BB/W007282/1) for funding this work

Depletion of Scleraxis-lineage (ScxLin) cells in adult tendon recapitulates age-related decrements in cell density, ECM organization and composition. However, depletion of ScxLin cells improves tendon healing, relative to age-matched wildtype mice, while aging impairs healing. Therefore, we examined whether ScxLin depletion and aging result in comparable shifts in the tendon cell environment and defined the intrinsic programmatic shifts that occur with natural aging, to define the key regulators of age-related healing deficits. ScxLin cells were depleted in 3M-old Scx-Cre+; Rosa-DTRF/+ mice via diphtheria toxin injections into the hindpaw. Rosa-DTRF/+ mice were used as wildtype (WT) controls. Tendons were harvested from 6M-old ScxLin depleted and WT mice, and 21-month-old (21M) C57Bl/6 mice (aged). FDL tendons (n=6) were harvested for single-cell RNAseq, pooled, collagenase digested, and sorted for single cell capture. Data was processed using Cell Ranger and then aligned to the annotated mouse genome (mm10). Filtering, unsupervised cell clustering, and differential gene expression (DEG) analysis were performed using Seurat. Following integration and sub-clustering of the tenocyte populations, five distinct subpopulations were observed. In both ScxLin depletion and aging, ‘ECM synthesizers’ and ‘ECM organizers’ populations were lost, consistent with disruptions in tissue homeostasis and altered ECM composition. However, in ScxLin depleted mice retention of a ‘specialized ECM remodeler’ population was observed, while aging tendon cells demonstrated inflammatory skewing with retention of a ‘pro-inflammatory tenocyte population’. In addition, enrichment of genes associated with protein misfolding clearance were observed in aged tenocytes. Finally, a similar inflammatory skewing was observed in aged tendon-resident macrophages, with this skewing not observed in ScxLin depleted tendons. These data suggest that loss of ‘ECM synthesizer’ populations underpins disruptions in tendon homeostasis. However, retention of ‘specialized remodelers’ promotes enhanced healing (ScxLin depletion), while inflammatory skewing may drive the impaired healing response in aged tendons

Introduction. Most western countries have implemented fast-track hip fracture aiming at surgery within 24 hours, since the mortality rate hereafter rises markedly. In Greenland, it is not achievable to operate within 24 hours. Arctic people live in sparsely populated areas and Greenland's population is scattered along the vast coastline. All patients must be chartered to Nuuk by airplane which can take up till several days to weeks, due to logistics and the Arctic weather. This presents a challenge regarding adhering to western guidelines. The operative delay may be acceptable though, as it is the impression that the Greenlandic population survives and endures better than patients of western populations. However, as data are lacking, we aimed to describe mortality among hip fracture patients in Greenland taking frailty and comorbidities into account. Method. All patients with ICD-10 codes DS720, DS721 and DS722 from 2018-2022 were identified as 261 patients diagnosed with hip fractures. Variables including time of diagnosis, time to operation, reasons for delay, ASA-score, Charlson Comorbidity index, time of death, and other possible confounding variables were analyzed. Primary outcome was mortality rates at 30-day post-OP and 1-year post-OP. Results. The average time from fracture to operation was 91.4 hours. In the Danish Cohort (DC) 70,6 % of patient were operated within 24 hours. Overall, 30-day mortality was 9,9 %, and 1-year mortality was 29,4 %, compared to the DC with 10,8 % 30-day mortality and 28,3 % 1-year mortality. Multivariate regression was conducted, showing no statiscal significant increase in mortality, despite extended delay. Conclusion. With no increase in death, the authors find it justifiable that patients in Greenland endure longer delays than the western population. The influence on further adverse effects needs to be investigated as well as causes of survival, but perhaps the Arctic people unveil mechanisms for raised survival among other populations

Autografts containing bone marrow (BM) are current gold standard in the treatment of critical size bone defects, delayed union and bone nonunion defects. Although reaching unprecedented healing rates in bone reconstruction, the mode of action and cell-cell interactions of bone marrow mononuclear cell (BM-MNC) populations have not yet been described. BM-MNCs consist of a heterogeneous mixture of hematopoetic and non-hematopoetic lineage fractions. Cell culture in a 3D environment is necessary to reflect on the complex mix of these adherend and non-adherend cells in a physiologically relevant context. Therefore, the main aim of this approach was to establish conditions for a stable 3D BM-MNC culture to assess cellular responses on fracture healing strategies. BM samples were obtained from residual material after surgery with positive ethical vote and informed consent of the patients. BM-MNCs were isolated by density gradient centrifugation, and cellular composition was determined by flow cytometry to obtain unbiased data sets on contained cell populations. Collagen from rat tail and human fibrin was used to facilitate a 3D culture environment for the BM-MNCs over a period of three days. Effects on cellular composition that could improve the regenerative potential of BM-MNCs within the BM autograft were assessed using flow cytometry. Cell-cell-interactions were visualized using confocal microscopy over a period of 24 hours. Cell localization and interaction partners were characterized using immunofluorescence labeled paraffin sectioning. Main BM-MNC populations like Monocytes, Macrophages, T cells and endothelial progenitor cells were determined and could be conserved in 3D culture over a period of three days. The 3D cultures will be further treated with already clinically available reagents that lead to effects even within a short-term exposure to stimulate angiogenic, osteogenic or immunomodulatory properties. These measures will help to ease the translation from “bench to bedside” into an intraoperative protocol in the end

Abstract. Objectives. Osteoarthritis (OA) is a complex joint disorder characterised by the loss of extracellular matrix (ECM) leading to cartilage degeneration. Changes to cartilage cell (chondrocyte) behaviour occur including cell swelling, the development of fine cytoplasmic processes and cell clustering leading to changes in cell phenotype and development of focal areas of mechanically-weak fibrocartilaginous matrix. [1]. To study the sequence of events in more detail, we have investigated the changes to in situ chondrocytes within human cartilage which has been lightly scraped and then cultured with serum. Methods. Human femoral heads were obtained with Ethical permission and consent from four female patients (mean age 74 yrs) undergoing hip arthroplasty following femoral neck fracture. Osteochondral explants of macroscopically-normal cartilage were cultured as a non-scraped control, or scraped gently six times with a scalpel blade and both maintained in culture for up to 2wks in Dulbecco's Modified Eagle's Medium (DMEM) with 25% human serum (HS). Explants were then labelled with CMFDA (5-chloromethylfluorescein-diacetate) and PI (propidium iodide) (10μM each) to identify the morphology of living or dead chondrocytes respectively. Explants were imaged using confocal microscopy and in situ chondrocyte morphology, volume and clustering assessed quantitatively within standardised regions of interest (ROI) using Imaris. ®. imaging software. Results. Within 2wks of culture with HS, chondrocyte volume increased significantly from 412±9.3µm. 3. (unscraped) at day 0 to 724±16.6 µm. 3. (scraped) [N(n) = 4(380)] (P=0.0002). Chondrocyte clustering was a prominent feature of HS culture as the percentage of clusters in the cell population increased with scraping from 4.8±1.4% to 14.9±3.9% [N(n) = 4(999)] at week 2 (P=0.0116). In addition, the % of the chondrocyte population within clusters increased from approximately 38% to 60%, and the number of cells per cluster increased significantly from 3.2±0.08 to 4±0.22 (P=0.031). The development of abnormal ‘fibroblastic-like’ chondrocyte morphology demonstrating long (>5µm) cytoplasmic processes also occurred, however the time course of this was more variable. For some samples, clustering occurred before abnormal morphology, but for others the opposite occurred. Typically, by the second week, 17±2.64% of the cell population had processes and this increased to 22±4.02% [N(n) = 4(759)] with scraping. Conclusions. Scraping the cartilage will remove surface constituents including lubricants (e.g. lubricin, hyaluronic acid, phospholipids), extracellular matrix constituents (collagen, proteoglycans – potentially the ‘lamina splendens’) and cells (chondrocytes and mesenchymal stromal cells (MSCs)). Although we do not know which of these component(s) is important, the effect is to dramatically increase the permeation of serum factors into the cartilage matrix and signal the development of cytoplasmic processes, cell clustering and swelling. It is notable that these cellular changes are similar to those occurring in early OA. [1]. This raises the interesting possibility that scraped cartilage cultured with human serum recapitulates some of the changes to in situ chondrocytes during early stages of cartilage degeneration and as such, could be a useful model for following the deleterious changes to matrix metabolism. 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

Heterotopic ossification (HO) is defined as aberrant bone formation in extraskeletal locations. In this process, local stromal cells of mesenchymal origin abnormally differentiate, resulting in pathologic cartilage and bone matrix deposition. However, the specific cell type and mechanisms beyond this process are not well understood, in part due to the heterogeneity of progenitor cells involved. Here, a combination of single cell RNA sequencing (scRNA-Seq) and lineage tracing, defined the extent to which synovial / tendon sheath progenitor cells contribute to HO. For this purpose, a Tppp3 (tubulin polymerization-promoting protein family member 3) inducible reporter model was used, in combination with either Scx (Scleraxis) or Pdgfra (Platelet derived growth factor receptor alpha) reporter animals. Both arthroplasty-induced and tendon injury-mouse experimental HO models were utilized. ScRNA-Seq of tendon-induced traumatic HO suggested that Tppp3 is a progenitor cell marker for either osteochondral or tendon or cells. After HO induction, Tppp3 reporter+ cell population expanded in number and contributed to cartilage and bone formation in tendon and joint-associated HO. Using double reporter animals, we found that both Pdgfra+Tppp3+ and Pdgfra+Tppp3- progenitor cells produced HO-associated cartilage. Finally, the examination of human samples showed a significant population of TPPP3+ cells overlapping with osteogenic markers in areas of HO. Overall, these results provide novel observations that peritenon and synovial progenitor cells undergo abnormal osteochondral differentiation and contribute to heterotopic bone formation after trauma