Aims. Our retrospective analysis reports the outcome of patients operated for slipped capital femoral epiphysis using the modified Dunn procedure. Results, complications, and the need for revision surgery are compared with the recent literature. Methods. We retrospectively evaluated 17 patients (18 hips) who underwent the modified Dunn procedure for the treatment of slipped capital femoral epiphysis. Outcome measurement included standardized scores. Clinical assessment included ambulation, leg length discrepancy, and hip mobility. Radiographically, the quality of epiphyseal reduction was evaluated using the Southwick and Alpha-angles. Avascular necrosis, heterotopic ossifications, and osteoarthritis were documented at follow-up. Results. At a mean follow-up of more than nine years, the mean modified Harris Hip score was 88.7 points, the Hip Disability and Osteoarthritis Outcome Score (HOOS) 87.4 , the Merle d’Aubigné Score 16.5 points, and the UCLA Activity Score 8.4. One patient developed a partial avascular necrosis of the femoral head, and one patient already had an avascular necrosis at the time of delayed diagnosis. Two hips developed osteoarthritic signs at 14 and 16 years after the index operation. Six patients needed a total of nine revision surgeries. One operation was needed for postoperative hip subluxation, one for secondary displacement and implant failure, two for late femoroacetabular impingement, one for femoroacetabular impingement of the opposite hip, and four for implant removal. Conclusion. Our series shows good results and is comparable to previous published studies. The modified Dunn procedure allows the anatomic repositioning of the slipped epiphysis. Long-term results with subjective and objective hip function are superior, avascular necrosis and development of osteoarthritis inferior to other reported treatment modalities. Nevertheless, the procedure is technically demanding and revision surgery for secondary femoroacetabular impingement and implant removal are frequent. Cite this article: 2020;1-4:80–87

Aim: To compare outcomes in patients who suffered a severe slipped upper femoral epiphysis (SUFE) treated by either a modified Dunn or Imhauser Osteotomy. Method: A consecutive group of patients were identified retrospectively from the operative records of a single surgeon at two hospitals since 2003. Patient Notes were used to extract age at presentation, duration of symptoms, stability, and time to surgery. Radiographs were examined to determine: the slip angle; and the degree of correction achieved. Patients were assessed using the Harris and Oxford Hip Scores. Results: Seven patients had a modified Dunn osteotomy and 11 patients an Imhauser osteotomy. Of those only 6 of the Dunn patients and 7 of the Imhauser patients could be recalled for clinical assessment. The average time to clinical assessment from osteotomy was 13.5 months for the Dunn group and 32 months for the Imhauser group. Post-operative lateral radiographs showed a mean angle of deformity correction of 63 degrees in the Dunn and 36 degrees in the Imhauser groups. There were no postoperative complications in either group, specifically no avascular necrosis. In the Dunn group the Harris Hip Score ranged from 78 to 100, mean 92 (excellent) and the Oxford Hip scores from 12 to 21, mean 17. The Harris Hip Score for the Imhauser group ranged from 50 to 98, mean 76 (fair), and the Oxford scores from 13 to 34, mean 25. Range of motion was similar for both groups in all directions. Conclusions: The Dunn and Imhauser osteotomies both give good clinical results in the severe SUFE patient. However the Dunn Osteotomy group had better Harris and Oxford Hip Scores, reflecting improved functional outcome

The modified Dunn procedure has the potential to restore the anatomy in hips with slipped capital femoral epiphyses (SCFE) while protecting the blood supply to the femoral head. However, there is controversy about the risks associated with the procedure especially in the most severe capital slips. Therefore, we report on (1) clinical outcome, (2) the cumulative survivorship with endpoints AVN and/or OA progression and (3) radiographic anatomy of the proximal femur at followup in patients treated with a modified Dunn procedure for severe SCFE. We performed a retrospective analysis involving 46 hips of 46 patients treated with a modified Dunn procedure for severe SCFE (slip angle >60°) between 1999 and 2016. Followup averaged 8 years, (range 1–17) with 2 patients lost to followup after one year. The mean age was 13 years (range 9–19 years). Mean preoperative slip angle was 64° (range 60–90) and 14 out of 46 hips (30%) presented with unstable slips. Clinical scores and PROMs were evaluated and the hips were followed standard x-rays. Cumulative survivorship (Kaplan-Meier) with three defined endpoints: (1) AVN; (2) progression by at least one OA grade according to Tönnis; (3) non-preserved hip joint. (1)Mean Harris Hip score (HHS) was 93 points (66–100) and mean Hip Disability and Osteoarthritis Outcome Score (HOOS) was 90 points (67–100) at last followup. (2)Cumulative survivorship was 93% at 10-year followup. Three hips reached an endpoint. Two hips (4%) had AVN, one of them underwent hip arthrodesis. One hip had OA progression. (3)Postoperative slip angle was 7° (1–16). Alpha angle on axial radiograph was 39° (26–71) at followup. 41/44 hips (93%) had no OA (Tönnis 0). The modified Dunn procedure largely corrected slip deformities with low apparent risk of progression to avascular necrosis or osteoarthritis at mean 8-years followup. The AVN rate in severe and unstable (30%) capital slip was 4% (2 hips) with this procedure

Introduction. We present a single surgeon series of 20 modified Dunn osteotomies without surgical dislocation of the femoral head for slipped upper femoral epiphysis (SUFE). Method. All patients from 2007 to 2011 who had a Dunn osteotomy for SUFE had their notes reviewed and we obtained an updated Non Arthritic Hip Score. Results. 20 patients were identified, of which 5 were female, with a combined average age of 14. The average duration of symptoms prior to the procedure was 10.2 weeks (range, 4–78). Classifications divided the cases into 7 chronic slips, 7 acute-on-chronic, and 5 acute., and 7 of the cases were unstable slips with an average slip angle of 71 degrees (range 65–85). All slips were grade 3. Average follow up was 26.2 months (range, 2–62). 3 developed avasular necrosis (2 unstable, 1 stable) and 2 patients had symptomatic leg length discrepancy. Preoperative MRI scans were performed in 4 patients and showed vascular compromise, but this did not always correlate with intraoperative findings of avascularity when the head was drilled. The average Nonarthritic hip score was 71.6 (range, 60–80). Summary. Dunn osteotomies are safe in patients with chronic slips, and have a low incidence of AVN. Overall function was good, even in those patients with segmental AVN scoring highly on their hip scores. Keeping the ligamentum teres intact and not dislocating the femoral head may improve vascularity of the head. Vascularity may also be assessed by preoperative MRI scans, although radiological suggestion of an avascular head which contradicted clinical findings and postoperative outcome may be due to transient vessel spasm

The risk of AVN is high in Unstable Slipped Capital Femoral Epiphysis (SCFE) and the optimal surgical treatment remains controversial. Our AVN rates in severe, unstable SCFE remained unchanged following the introduction of the Modified Dunn Procedure (MDP) and as a result, our practice evolved towards performing an Anterior Open Reduction and Decompression (AOR) in an attempt to potentially reduce the “second hit” phenomenon that may contribute. The aim of this study was to determine the early surgical outcomes in Unstable SCFE following AOR compared to the MDP. All moderate to severe, Loder unstable SCFEs between 2008 and 2022 undergoing either an AOR or MDP were included. AVN was defined as a non-viable post-operative SPECT-CT scan. Eighteen patients who underwent AOR and 100 who underwent MPD were included. There was no significant difference in severity (mean PSA 64 vs 66 degrees, p = 0.641), or delay to surgery (p = 0.973) between each group. There was no significant difference in the AVN rate at 27.8% compared to 24% in the AOR and MDP groups respectively (p = 0.732). The mean operative time in the AOR group was 24 minutes less, however this was not statistically significant (p = 0.084). The post-reduction PSA was 26 degrees (range, 13–39) in the AOR group and 9 degrees (range, -7 to 29) in the MDP group (p<0.001). Intra-operative femoral head monitoring had a lower positive predictive value in the AOR group (71% compared to 90%). Preliminary results suggest the AVN rate is not significantly different following AOR. There is less of an associated learning curve with the AOR, but as anticipated, a less anatomical reduction was achieved in this group. We still feel that there is a role for the MDP in unstable slips with a larger remodelling component

Introduction. Hips following in-situ pinning for slipped capital femoral epiphysis (SCFE) have an altered morphology of the proximal femur with cam type deformity. This deformity can result in femoroacetabular impingement and early joint degeneration. The modified Dunn procedure allows to reorientate the slipped epiphysis to restore hip morphology and function. Objectives. To evaluate (1) hip pain and function, (2) 10-year survival rate and (3) subsequent surgeries and complications in hips undergoing modified Dunn procedure for SCFE. Methods. Between April 1998 and December 2005 we performed the modified Dunn procedure for 43 patients (43 hips) with SCFE. Twenty-five hips (58) presented with an acute or acute on chronic slip. The mean slip angle was 43° (range, 15° – 80°). A majority of 53% of procedures were performed in male patients and the mean age at operation was 13 years (10 – 19 years). We could followup all except one hip (followup of 5.5 year) for a minimum of 10 years (mean followup 13 [10 – 18 years]). We used the anterior impingement test to assess pain and the Merle d'Aubigné- ostel score to assess function. Survivorship calculation was performed using the method of Kaplan and Meier and any of the following factors as a definition of failure: radiographic evidence of worsening osteoarthritis (OA), or a Merle d'Aubigné-Postel score less than 15. Results. (1) The prevalence of a positive anterior impingement test decreased from 100% to 16% (p<0.001). The mean Merle d'Aubigné-Postel score improved from 13 (7 – 14) to 17 (14 – 18) at most recent followup (p<0.001). (2) Four hips (9%) showed progression of OA and three hips (7%) had a Merle d'Aubigné-Postel score of less than 15 at most recent followup. This resulted in a 93% survival rate at 10-year followup. (3) No hip developed avascular necrosis. Five hips (12%) had complications with reosteosynthesis due to screw breakage or nonunion. Another nine hips (21%) had subsequent surgeries including acetabular rim trimming / offset creation in 5 hips and screw removal in 4 hips. Conclusion. The modified Dunn procedure is a safe method to correct the morphology of the proximal femur in hips with SCFE. Ninety-free percent of the hips showed no progression of OA and a good clinical result at the 10-year followup. Twelve percent required revision surgery for complications all including screw breakage with nonunion of the greater trochanter

Introduction. We present an all arthroscopic technique for modified Weaver Dunn reconstruction of symptomatic chronic type III acromioclavicular joint injuries. Method. Over a 1 year period we performed 12 all arthroscopic modified Weaver-Dunn procedures. All patients had failed non-operative management for at least 6 months, with symptoms of pain and difficulty with overhead activities. The technique involved excision of the lateral end of clavicle, stabilisation with a suture cerclage technique from 2 anchors placed in the base of the coracoid and coracoacromial ligament transfer from the acromion to lateral end of clavicle. The technique is identical to our open technique and those published previously by Imhoff. Post-operatively the patients were immobilised for six weeks, followed by an active rehabilitation programme and return to work and sports at 3 months. Results. We have currently performed this technique in 12 patients, all male. The average age at operation was 25.8yrs at a mean interval of 11 months post-injury. The mean Constant score pre-operatively was 49 (44-54). The mean 3 month post-operative Constant score was 88.6 (84-96). There have been no complications, and the 2 professional sportsmen within our cohort returned to full contact at 3 months. Due to an irreducible clavicle, one patient required an open excision of lateral clavicle, with the rest of the procedure performed arthroscopically. Discussion. Arthroscopic Weaver-Dunn has a number of advantages over the corresponding open procedure. It avoids the detachment of deltoid needed to gain exposure and also the morbidity from the wound. From our experience it enables patients to regain their function more rapidly with an earlier return to sporting activities. Conclusion. The early results from our initial experience have been excellent, with no complications. With this technique an anatomic reconstruction can be achieved with excellent cosmesis, low morbidity and potentially accelerated rehabilitation

Airn: Treatment of acromioclavicular joint dislocations depends on the type of the dislocation and the patients symptoms. We present the results of surgical treatment with transfer of the acromical end of coracoacromial ligament in the distal end of the clavicle. (The Weaver Dunn procedure). Material – Method: 32 patients with acromioclavicular dislocation type III, IV and V according Rockwood, 20 acute and 12 chronic, were treated with open reduction and stabilization of the distal end of clavicle and transfer of the coracoacromial ligament. They were 26 men and 6 women, the average age was 28 years. The indications for the operation were: deformity, pain and numbness. On 28 patients resection of the distal end of the clavicle was performed but on 4 acute dislocations the stabilization was made without osteotomy. Surgery was performed with the patients in the beach chair position and with a horizontal skin incision above the acromioclavicular joint. The length of the coracoacromial ligament was determinant to achieved reduction. The soft tissues were double breasted above the acromioclavicular joint. After surgery the limb was placed in a sling for 15 days and then complete mobilization exercises was began. Draft weight was avoided for 3 months. Results: The average length of follow up was 4 years. All patients had almost no pain and full range of motion. Constant score was above 80 in all cases. Full range of motion was obtained until 2 months after operation. In 3 cases the primary reduction was not fully achieved. In 3 other cases loss of the primary reduction was observed due to suture rupture. In these cases the displacement was significantly minor than pre operatively. 15 patients had developed ectopic ossification bellow the acromioclavicular joint without consequence in the shoulder motion. The resection of the distal end of the clavicle did not alter the results. Conclusion: The operation offers low percentage of complications and quick rehabilitation. It is recommended in acute as well in chronic injuries with very good results. The good results were not varied with time during follow up. Advantage of this operation represents the no use of metals. The pull angle of the ligament might create an anterior sublaxation during reduction of the dislocation, but this does not influence the results

We present an all arthroscopic technique for modified Weaver Dunn reconstruction of symptomatic chronic type III ACJ joint injuries. Over a one year period we performed 12 all arthroscopic modified Weaver-Dunn procedures. All patients had failed non-operative management for at least 6 months. The technique involved excision of the lateral end of clavicle, stabilisation with a suture cerclage technique from 2 anchors placed in the base of the coracoid and coracoacromial ligament transfer from the acromion to lateral end of clavicle. Post-operatively the patients were immobilised for six weeks, followed by an active rehabilitation programme and return to work and sports at 3 months. We have currently performed this technique in 12 patients, all male. The average age at operation was 25.8yrs at a mean interval of 11 months post injury. The mean Constant score preoperatively was 49 (44–54). The mean 3 month postoperative Constant score was 88.6 (84–96). There have been no complications, and the 2 professional sportsmen within our cohort returned to full contact at 3 months. Due to an irreducible clavicle, one patient required an open excision of lateral clavicle, with the rest of the procedure performed arthroscopically. Arthroscopic Weaver-Dunn has a number of advantages over the corresponding open procedure. It avoids the detachment of deltoid needed to gain exposure and also the morbidity from the wound. From our experience is that it enables patients to regain their function more rapidly with an earlier return to sporting activities. The early results from our initial experience have been excellent, with no complications. With this technique an anatomic reconstruction can be achieved with excellent cosmesis, low morbidity and potentially accelerated rehabilitation

Introduction

In situ pinning for classic slipped capital femoral epiphysis(SLIP) is evolving to a more direct and anatomic realignment of proximal femoral epiphysis; but in no study the result of such a treatment in Valgus Slip, an uncommon type of slipped capital femoral epiphysis, has been reported.

Background. Leg pain frequently accompanies low back pain and is associated with increased levels of disability and higher health costs than simple low back pain. Distinguishing between different types of low back- related leg pain (LBLP) is important for clinical management and research applications. The aim of this systematic review was to identify, describe and appraise papers that classify or subgroup populations with LBLP. Methods. The search strategy involved nine electronic databases including Medline and Embase, reference lists of eligible studies and relevant reviews. Selected papers were quality appraised independently by two reviewers using a standardised scoring tool. Results. Of 13,337 potential eligible citations, 49 relevant papers were identified that reported on 20 classification systems. Papers were grouped according to purpose and criteria of the classification systems. Five themes emerged: (i) pathoanatomical sources of pain (ii) clinical features, (iii) pain mechanisms, (iv) treatment based approach and (v) screening tools and prediction rules. Four of the twenty systems focused specifically on LBLP populations. Pain mechanisms and treatment based approach systems scored highest following quality appraisal as authors generally included statistical methods to develop their classifications and supporting work had been published on the systems' validity, reliability and generalizability. Conclusion. Numerous classification systems exist that include patients with leg pain, a minority of them focus specifically on distinguishing between different presentations of leg pain. Further work is needed to identify clinically meaningful subgroups of LBLP patients, ideally based on large primary care cohort populations and using stringent methods for classification system development. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting. Conflicts of interest: No conflicts of interest. S Stynes is supported by an NIHR/HEE Clinical Doctoral Research Fellowship. Dr Konstantinou is supported by an HEFCE/NIHR Senior Clinical Lectureship. Professor Dunn is supported by the Wellcome Trust (083572)

Background. 60% of back pain patients report pain radiation in the leg(s), which is associated with worse symptoms and poorer recovery. The majority are treated in primary care, but detailed information about them is scarce. The objective of this study is to describe the characteristics of patients with back and leg pain-seeking treatment in primary care. Methods. Adult patients consulting their GP with back and leg pain were invited to the study. Participants completed questionnaires including sociodemographic, physical and psychosocial measures. They also underwent standardised clinical assessments by physiotherapists, and received an MRI scan. Results. 609 patients participated with 67.5% reporting pain below the knee. 62.6% were female, sample mean (SD) age 50.2 (13.9). 367 (60.7%) were in paid employment with 39.7% reporting time off work. Mean disability (RMDQ) was 12.7 (5.7) and mean pain intensity was 5.6 (2.2) and 5.2 (2.4) for back and leg respectively. Mean sciatica bothersomeness index (SBI) score was 14.9 (5.1). 74.2% (452/609) were clinically diagnosed as having sciatica. Patients in the sciatica group reported significantly higher levels of leg pain and SBI scores, leg pain worse than back pain and pain below the knee. Neuropathic pain was more prevalent in patients with referred leg pain. Conclusion. This primary care cohort reported high levels of disability and pain. Three quarters were diagnosed with sciatica. Follow-up of this cohort will investigate the prognostic value of their baseline characteristics. This abstract summarises independent research funded by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research Programme (Grant Reference Number RP-PG-0707-10131). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting. Conflicts of interest: No conflicts of interest. K. Konstantinou is supported by a HEFCE/NIHR Senior Clinical Lectureship. KM Dunn is supported by the Wellcome Trust (083572)

To analyse the causes and factors associated with mortality in patients admitted to ASCI unit in a low- or middle-income country. The study was performed at a Tertiary Hospital at Groote Schuur Hospital, Cape Town South Africa

Data between 1996 –2022 were retrospectively collected from hospital records of patients admitted to the ASCI Unit. There was approximately 3223 admissions for the study period. 682 patients were confirmed dead 87% were male and 64% were unemployed. The mean age was 46 years (ranging from 14 – 87 years).

A 1/3 of injuries were caused by a MVA, a ¼ by a fall (low energy and from a height), and 1/5 by a gunshot wound. Average length of stay was 47 days (SD = 52 days), ranging from as short as 1 day to 512 days for one patient. Majority (65%) were admitted for more than a week but less than 2 months 32% were ventilated, and 17% with a CPAP facemask. 10% of patients had a pre-existing ulcer prior to admission. 65% of patients had surgery via the posterior approach, 33% via the anterior approach. On average patients died within 5 years of being admitted to hospital, ranging from dying in the same year as the injury to 20 years later. 73% of the deaths were classified as natural deaths and 20% as unnatural.

There is a high mortality in patients with acute spinal cord injury, causes are multifactorial, and in depth critical analyses is required to improve clinical outcomes and rationalise resource allocation.

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional deformity of the spine characterized by a Cobb angle of at least 10 degrees. The goal of surgery is to not only prevent progression but restore sagittal and coronal balance, protecting cardiopulmonary function and improving cosmesis.

We reviewed the impact of deformity correction surgery in terms of radiology and patient reported outcome(PROMs).

The senior authors prospectively maintained database from 2003 –2022 was retrospectively analysed in terms of pre- and post-operative patient reported outcome measures (SRS 22) as well as radiological parameters.

44 patients with AIS were identified with pre and post op PROMS. The average age at surgery was 15yrs with 84% female. 38% had a Lenke 1 curve and 3 patients had Lenke 6 curves. 73% had posterior surgery.

There was a total improvement in SRS 22 scores by 7.8%. Patients reported significant satisfaction with treatment 4.8/5 and improvement in self-image with a change of 0.4 (p<0.001). However, no difference in function, pain and mental health were recorded.

Overall, proximal thoracic (PT) curves improved from 24 degrees to 11 degrees (p<0.001), Main thoracic (MT) curve 55 degrees to 19 degrees and Thoracolumbar/Lumbar curves (TL/L) 45 degreesto 11 degrees. Pre-operative flexibility and post-operative correction were 0.40 and 0.41 respectively for PT curve. MT was 0.32 and 0.67. That for TL/L was 0.57 and 0.71 respectively.

Surgery yields significant main curve correction correlating with high patient reported satisfaction rate. Although total SRS 22 score yielded 7.8% improvement, sub-analysis of self-image showed the most significant improvement.

Background. People with back pain often experience long-term pain with recurrences and fluctuations. However, few studies have considered which factors predict long-term outcomes. Purpose. To determine the prognostic factors, measured around the time of a primary care back pain consultation, that predict clinically significant pain in both the short (6 months) and long-term (5 years). Methods. Back pain consulters at 8 GP practices received a questionnaire shortly after consultation. Information was collected on potential prognostic factors: demographics (age, gender, educational, social class), physical (pain, disability, pain duration, distal leg pain), psychological (illness perceptions, coping, fear avoidance, pain self-efficacy, depression, anxiety) and occupational (work status). Patients were followed-up by postal questionnaire 6 months and 5 years later. The Chronic Pain Grade was used to define clinically significant pain at outcome. Results. Baseline pain intensity (Relative Risk (RR) 1.12, 95% CI 1.03, 1.20) and a strong patient belief that their LBP would last a long time (RR 1.04, 95% CI 1.01, 1.07) predicted outcome at 6 months. Outcome at 5 years was best predicted by a similar model: pain intensity (RR 1.09, 95% CI 0.997, 1.20) and a strong belief that their back pain would persist (RR 1.06, 95% CI 1.03, 1.09). Conclusion. Pain intensity and a belief by the patient that their back pain will last a long time predicted clinically significant pain in both the short and long-term. Both predictors have the potential for clinical intervention at the consultation stage. No conflicts of interest. Source of funding: The baseline and 6-month follow-up phases of this study was supported financially by a Programme Grant awarded by the Arthritis Research UK [13413] and the 5-year follow-up phase was completed as part of Dr KM Dunn's Wellcome Trust Grant [083572]. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting

Adolescent idiopathic scoliosis is a three-dimensional deformity of the spine, affecting 1–3% of the population.

Most cases are treated conservatively. Curves exceeding 45° in the thoracic spine and 40° in the lumbar spine may require correction and fusion surgery, to limit the progression of the curve and prevent restrictive pulmonary insufficiency (curves above 70°). When fusion is required, it may be performed either by posterior or anterior approaches. Posterior is useful for thoracic (Lenke I) curves, notably to correct the thoracic hypokyphosis frequently observed in AIS. Anterior approaches by thoraco-lombotomies allow an effective correction of thoraco-lumbar and lumbar curves (Lenke V and VI), with fewer levels fused than with posterior approaches. However, the approach requires diaphragm splitting and one may be concerned about the long-term pulmonary consequences. The literature provides conflicting insight regarding the consequences of the approach in anterior scoliosis correction, the interpretation of the results being difficult knowing that the correction of the scoliosis itself may improve pulmonary function.

This is a retrospective observational study done at a Tertiary Institution. The HRQOL scores have been collected as a prospective cohort. Clinical and radiographic data was collected from patients charts and analysed by two senior surgeons

A cohort of 64 patients were operated in the given time period. 50 patients met the inclusion criteria. No major complications were reported. The Union rate was 100% and no post operative complications were noted. Pre and post SRS scores improved in all patients.

The Anterior approach for Lenke V AIS gives great surgical exposure and allows for excellent correction of Cobb angle with minimal risk to the patient.

Introduction. Multiple studies have identified Cutibacterium acnes (C.acnes) and other microbes in intervertebral disc tissue using 16S DNA Sequencing and microbial cultures. However, it remains unclear whether these bacteria are native to the discs or result from perioperative contamination. Our study aimed to detect Gram-positive bacteria in non-herniated human disc samples and explore correlations with Toll-like receptors (TLR) 2, TLR4, NLRP3, and Gasdermin D. Methods. Immunohistochemical staining was conducted on 75 human IVD samples for Gram-positive bacteria, S. aureus, C.acnes, TLR2, TLR4, NLRP3, and Gasdermin D. Cell detection and classification were performed using QuPath. NP cells were treated with Lipopolysaccharide (LPS) and Peptidoglycan (PGN) in monolayer and alginate beads for up to 72 hours, followed by secretome analysis using Luminex. Statistical analysis included Kruskal-Wallis, Dunn's multiple comparison test, and Pearson correlation. Results. Immunohistochemical staining revealed Gram-positive bacteria exclusively within cells, with C. acnes positivity ranging from 5–99% and correlating with patient age (r=0.41, p= 0.007). TLR2 positivity ranged from 5–99% and TLR4 from 3–72%, showing a strong correlation (r= 0.62, p= 1.5e-006). Females with mid-degenerative grades exhibited significantly decreased TLR2 expression compared to those without degeneration signs. Treatment with LPS and PGN increased catabolic cyto- and chemokines associated with IVD degeneration. Conclusion. In conclusion, this study confirms Gram-positive bacteria presence in non-herniated human disc samples and highlights their role in triggering a catabolic response in disc cells. No conflicts of interest.  . Sources of funding. This project is part of the Disc4All Training network to advance integrated computational simulations in translational medicine, applies to intervertebral disc degeneration and funded by Horizon 2020 (H2020-MSCA-ITN-ETN-2020 GA: 955735)

Bone healing outcome is highly dependent on the initial mechanical fracture environment [1]. In vivo, direct bone healing requires absolute stability and an interfragmentary strain (IFS) below 2% [2]. In the majority of cases, however, endochondral ossification is engaged where frequency and amplitude of IFS are key factors. Still, at the cellular level, the influence of those parameters remains unknown. Understanding the regulation of naïve hMSC differentiation is essential for developing effective bone healing strategies. Human bone-marrow-derived MSC (KEK-ZH-NR: 2010–0444/0) were embedded in 8% gelatin methacryol. Samples (5mm Ø x 4mm) were subjected to 0, 10 and 30% compressive strain (5sec compression, 2hrs pause sequence for 14 days) using a multi-well uniaxial bioreactor (RISystem) and in presence of chondro-permissive medium (CP, DMEM HG, 1% NEAA, 10 µM ITS, 50 µg/mL ascorbic acid, and 100 mM Dex). Cell differentiation was assessed by qRT-PCR and histo-/immunohistology staining. Experiments were repeated 5 times with cells from 5 donors in duplicate. ANOVA with Tukey post-hoc correction or Kurskal-Wallis test with Dunn's correction was used. Data showed a strong upregulation of hypertrophic related genes COMP, MMP13 and Type 10 collagen upon stimulation when compared to chondrogenic SOX9, ACAN, Type 2 collagen or to osteoblastic related genes Type 1 Collagen, Runx2. When compared to chondrogenic control medium, cells in CP with or without stimulation showed low proteoglycan synthesis as shown by Safranine-O-green staining. In addition, the cells were significantly larger in 10% and 30% strain compared to control medium with 0% strain. Type 1 and 10 collagens immunostaining showed stronger Coll 10 expression in the samples subjected to strain compared to control. Uniaxial deformation seems to mainly promote hypertrophic-like chondrocyte differentiation of MSC. Osteogenic or potentially late hypertrophic related genes are also induced by strain. Acknowledgments: Funded by the AO Foundation, StrainBot sponsored by RISystemAG & PERRENS 101 GmbH

Many age-related diseases affect our skeletal system, but bone health-targeting drug development strategies still largely rely on 2D in vitro screenings. We aimed at developing a scaffold-free progenitor cell-based 3D biomineralization model for more physiological high-throughput screenings. MC3T3-E1 pre-osteoblast spheroids were cultured in V-shaped plates for 28 days in alpha-MEM (10% FCS, 1% L-Gln, 1X NEAA) with 1% pen/strep, changed every two days, and differentiation was induced by 10mM b-glycerophosphate and 50µg/ml ascorbic-acid. Osteogenic cell differentiation was assessed through profiling mRNA expression of selected osteogenic markers by efficiency corrected normalized 2^DDCq RT-qPCR. Biomineralization in spheroids was evaluated by histochemistry (Alizarin Red/von Kossa staining), Alkaline phosphatase (Alp) activity, Fourier transform infrared spectroscopy (FTIR) analyses, micro-CT analyses, and scanning electron microscopy on critical point-dried samples. GraphPad Prism 9 analyses comprised Shapiro-Wilk and Brown-Forsythe tests as well as 2-way ANOVA with Tukey post-hoc and non-parametric Kruskal-Wallis with Dunn post-hoc tests. During mineralization, as opposed to non-mineralizing conditions, characteristic mRNA expression profiles of selected early and late osteoblast differentiation markers (e.g., RunX, Alp, Col1a1, Bglap) were observed between day 0 and 28 of culture; Alp was strongly upregulated (p<0.001) from day 7 on, followed by its enzymatic activity (p<0.001). Bglap and Col1a1 expression peaked on (p<0.001) and from day 14 on (p<0.05), respectively. IHC revealed osteocalcin staining in the spheroid core regions at day 14, while type I collagen staining of the cores was most prominent from day 21 on. Alizarin Red and Von Kossa confirmed central and radially outwards expanding mineralization patterns between day 14 and day 28, which was accompanied by a steady increase in extracellular calcium deposition over time (p<0.001). Micro-CT analyses allowed quantitative appreciation of the overall increase in mineral density over time (day21, p<0.05; d28, p<0.001), while SEM-EDX and FTIR ultimately confirmed a bone-like hydroxyapatite mineral deposition in 3D. A novel and thoroughly characterized versatile bone-like 3D biomineralization in vitro model was established, which allows for studying effects of pharmacological interventions on bone mineralization ex vivo under physiomimetic conditions. Ongoing studies currently aim at elucidating in how far it specifically recapitulates intramembranous ossification

Aim. Differentiation of infected (INF) nonunion from aseptic (AS) nonunion is crucial for the choice of intra- and postoperative treatment. Preoperative diagnosis of infected nonunion is challenging, especially in case of low-grade infection lacking clinical signs of infection. Standard blood markers such as C-reactive protein or leucocyte count do not aid in preoperative diagnosis. Proteomic profiling has shown promising results for differentiation of numerous chronic disease states, and in this study was applied to preoperative blood samples of patients with nonunion in an attempt to identify potential biomarkers. Method. This prospective multicenter study enrolled patients undergoing revision surgery of femur or tibia nonunion. Patients with implant removal after regular fracture healing (HEAL) were included as a control-group. Preoperative blood samples, intraoperative tissue samples, sonication of osteosynthesis material and 1-year-follow-up questionnaire were taken. Nonunion patients were grouped into INF or AS after assessing bacterial culture and histopathology of retrieved samples. Diagnosis of infection followed the fracture related infection consensus group criteria, with additional consideration of healing one year after revision surgery. Targeted proteomics was used to investigate a predefined panel of 45 cytokines in preoperative blood samples. Statistical differences were calculated with Kruskal Wallis and Dunn's post hoc test. Cytokines with less than 80% of samples being above the lower limit of detection range (LLDR) were excluded for this study. Results. We recruited 62 AS, 43 INF and 32 HEAL patients. Patients in the two nonunion groups (INF and AS) did not differ concerning smoking, diabetes or initial open or closed fracture. Thirty-two cytokines were above LLDR in >80% of patients. INF patients showed a significant difference in expression of 8 cytokines compared to AS, with greatest differences observed for Macrophage Colony Stimulating Factor 1 (MCSF-1) and Hepatocyte Growth Factor (HGF) (p<0.01). In comparing AS with HEAL patients, 9 cytokines displayed significant differences, including interleukin (IL)-6, Vascular Endothelial Growth Factor A (VEGFA), Matrix Metalloproteinase 1 (MMP-1). Comparison of INF with HEAL patients revealed significantly different expression of 20 cytokines, including. IL-6, IL-18, VEGFA or MMP-1. Conclusions. Our study revealed differences in plasma cytokine profile of blood samples from INF and AS patients. Although no single biomarker is sufficient to differentiate these patients preoperatively in isolation, future multivariant analysis of this cytokine data in combination with clinical characteristics may provide valuable diagnostic insights. Funded by German Social Accident Insurance (FF-FR 0276) and AO Trauma (AR2021_04)