Aim. Arthroscopic interventions have revolutionized the treatment of joint pathologies. The appropriate diagnostics and treatment are required for infections after ligament reconstructions using non-resorbable material such as tendon grafts, anchors, and sutures, prone to biofilm formation. The infection rate is around 1% for knee and shoulder, while up to 4% for Achilles tendon reconstructions. Despite high number of these procedures worldwide, there is limited evidence about the best treatment protocol. Our study aimed to provide a general protocol for the treatment of small implants for soft tissue reconstruction. Method. Between 2019 and 2023, we treated 48 infections of ligament, meniscus, and tendon reconstructions out of 7291 related procedures performed in the same time period. Early infection (<30 days) were treated with an arthroscopic debridement and implant retention (DAIR), except Achilles tendons had open DAIR, while those with delayed or chronic infection (>30 days) were treated with extensive debridement and lavage combined with one-stage exchange (OSE) or implant removal. During surgery, at least 5 microbiological s and samples for histopathology were obtained. The removed material was sonicated. After surgery, all patients were one week on iv. antibiotics, followed by oral antibiofilm antibiotics for 6 weeks including rifampicin and/or a quinolone. All patients were followed for at least 1 year. Failure was defined as the need for additional revision surgery after finished iv. antibiotic treatment. Results. Among 48 patients, 38 were early and 10 were late acute or chronic infections. The incidence of infection for our cohort was 0.7%. We observed 27 infections after ligament reconstruction of the knee, 15 of the shoulder, 5 of the ankle, and 1 infection of the elbow joint. 40 patients were treated with DAIR, 5 with OSE, and 3 with implant removal. We had 11 C. acnes, 10 S. aureus, 6 S. epidermidis, 2 P. aeruginosa, 2 S. lugdunensis, 10 mixed flora, and 3 culture-negative infections. 12 patients received antibiotics before surgery, and all culture-negative infections were related to this subgroup. We observed 2 failures, both in a combination of proximal tibial osteotomy and ligament reconstruction of the knee joint. The success rate of our protocol was 96%. Conclusions. Prompt surgical treatment followed by 6 weeks of antibiotic treatment cured 96% of infections of small implants after reconstruction procedures of knee, shoulder, and ankle joints. Our study is the first to provide a treatment protocol for infections of small implants after ligament reconstruction procedures

Introduction. Supraspinatus and infraspinatus tears (Massive Rotator Cuff Tear- MRCT) cause compensatory activation of the teres minor (TM) and subscapularis (SubS) to maintain humeral head alignment. This study measures force changes in TM and SubS using a dynamic shoulder testing setup. We hypothesize that combining superior capsule reconstruction (SCR) and lower trapezius tendon (LTT) transfer will correct rotator cuff forces. Methods. Eight fresh-frozen human shoulder specimens from donors aged 55-75 (mean = 63.75 years), balanced for gender, averaging 219.5 lbs, were used. Rotator cuff and deltoid tendons were connected to force sensors through a pulley system, with the deltoid linked to a servohydraulic motor for dynamic force measurement. The system allowed unrestricted humeral abduction from 0 to 90 degrees. Results. Teres Minor (TM):. -. Control: 7.43 N (SD = 1.66). -. SS tear: 5.46 N (SD = 1.45). -. MRCT: 3.94 N (SD = 1.43). -. LTT post-MRCT: 5.85 N (SD = 1.13). -. SCR post-MRCT: 4.68 N (SD = 0.71). -. Combined LTT+SCR: 6.43 N (SD = 1.24). -. TM force reduction: 26.51% post-SS tear, 46.97% from intact to MRCT, 63.20% increase with LTT+SCR. Subscapularis (SubS):. -. Control: -0.73 N (SD = 0.43). -. SS tear: -0.46 N (SD = 0.36), 36.99% increase. -. MRCT: 0.96 N (SD = 0.47), 31.51% increase. -. LTT post-MRCT: -0.32 N (SD = 0.47), 66.67% reduction. -. SCR post-MRCT: -0.28 N (SD = 0.16), 70.83% reduction. -. Combined LTT+SCR: -0.66 N (SD = 0.32), 31.25% reduction. Non-parametric Friedman's ANOVA showed overall statistical significance for TM (P = 1.083×10. -6. ) and SubS (P = 4.77×10. -4. ). Conclusion. The cadaveric model assesses rotator cuff compensations, showing significant TM force reductions following rotator cuff tears and improvements with LTT and SCR, particularly when combined. SubS exhibited negative force during normal abduction but compensated during MRCT, returning to normal values post-LTT and SCR

Introduction. Histology is still considered the gold standard method for the evaluation of soft tissues in the musculoskeletal field, thanks to the possibility of studying structures using different staining and high magnification microscopy. To overcome the intrinsic limits of this method, contrast enhanced microtomographic (CE- microCT) protocols are constantly evolving to allow 3D study of soft tissues. However, no standardized approaches are available, and many concerns exist about the alterations induced to the samples. Method. microCT/histology protocols were explored on human tendons and menisci. To enhance contrast tissues for microCT scanning 1) examethyldisilazane drying 2) 2% phosphotungstic acid (PTA) in alcoholic solution exposition and 3) 2% PTA in aqueous solution exposition were performed; to observe PTA contrast progression, three exposition and scanning times were selected. microCT images were compared to histological slices obtained from the same samples, after rehydration protocols, or from adjacent tissues portion, stained with Picrosirius red to highlight the peculiar collagenic structures. Result. Exposition times influence PTA diffusion and tissue contrast; its specificity for collagenic structure allow a clearer contrast of the tissues. Histological processing on the same samples is possible: PTA removal requires careful washing in basic solution to reduce the hardening of the sample, while drying can be reverted applying inverse protocol. Comparison with microCT images is really accurate if histology is performed on the same sample, although all protocols induce tissue shrinkage with relative packing of collagen fibers. Conclusion. The contrast approaches tested proved effective in highlighting the structures of both tendons and menisci, but the structural effects induced by tissue shrinkage do not allow a completely real microCT visualization of native tissue. Histology can be the reference method to monitor the efficacy of the contrast methods and the alterations induced to define the possibility of improvement of the technique. Acknowledgement. PR23-PAS-P4 “ADJOINT 2”- INAIL

Introduction. Tendon ruptures are a common injury and often require surgical intervention to heal. A refixation is commonly performed with high-strength suture material. However, slipping of the thread is unavoidable even at 7 knots potentially leading to reduced compression of the sutured tendon at its footprint. This study aimed to evaluate the biomechanical properties and effectiveness of a novel dynamic high-strength suture, featuring self-tightening properties. Method. Distal biceps tendon rupture tenotomies and subsequent repairs were performed in sixteen paired human forearms using either conventional or the novel dynamic high-strength sutures in a paired design. Each tendon repair utilized an intramedullary biceps button for radial fixation. Biomechanical testing aimed to simulate an aggressive postoperative rehabilitation protocol stressing the repaired constructs. For that purpose, each specimen underwent in nine sequential days a daily mobilization over 300 cycles under 0-50 N loading, followed by a final destructive test. Result. After the ninth day of cyclic loading, specimens treated with the dynamic suture exhibited significantly less tendon elongation at both proximal and distal measurement sites (-0.569±2.734 mm and 0.681±1.871 mm) compared to the conventional suture group (4.506±2.169 mm and 3.575±1.716 mm), p=0.003/p<0.002. Gap formation at the bone-tendon interface was significantly lower following suturing using dynamic suture (2.0±1.6 mm) compared to conventional suture (4.5±2.2 mm), p=0.04. The maximum load at failure was similar in both treatment groups (dynamic suture: 374± 159 N; conventional suture: 379± 154 N), p=0.925. The predominant failure mechanism was breakout of the button from the bone (dynamic suture: 5/8; conventional suture: 6/8), followed by suture rupturing, suture unraveling and tendon cut-through. Conclusion. From a biomechanical perspective, the novel dynamic high-strength suture demonstrated higher resistance against gap formation at the bone tendon interface compared to the conventional suture, which may contribute to better postoperative tendon integrity and potentially quicker functional recovery in the clinical setting

Introduction. Tendon ruptures represent one of the most common acute tendon injuries in adults worldwide, affecting millions of people anually and becoming more prevalent due to longer life expectancies and sports activities. Current clinical treatments for full tears are unable to completely restore the torn tendons to their native composition, structure and mechanical properties. To address this clinical challenge, tissue-engineered substitutes will be developed to serve as functional replacements for total tendon ruptures that closely resemble the original tissue, restoring functionality. Method. Water borne polyurethanes (WBPU) containing acrylate groups, specifically polyethylene glycol methacrylate (PEGMA) or 2-hydroxyethyl methacrylate (HEMA), were combined with mouse mesenchymal stem cells (MoMSCs) and heparin sodium to formulate bioinks for the fabrication of scaffolds via extrusion-based 3D bioprinting. Result. The biocompatibility of acrylated-WBPUs was confirmed in 2D with MoMSCs using lactate dehydrogenase assay, DNA assay and live/dead assays. Cell-laden scaffolds were 3D-bioprinted by encapsulating MoMSCs at varying cell densities within the acrylated WBPUs. The resulting 3D structures support cell viability and proliferation within the scaffolds, as confirmed by live/dead assay, lactate dehydrogenase assay and DNA assays. Differentiation studies in the 3D-bioprinted scaffolds demonstrated the phenotype transition of MoMSCs toward tenocytes through gene expression and protein deposition analysis. The inclusion of sodium heparin in the bioinks revealed increased synthesis of matrix assembly proteins within the 3D-bioprinted constructs. Conclusion. The developed bioinks were biocompatible and printable, supporting cell viability within the 3D-bioprinted scaffold. The fabricated cell-laden constructs sustained cell proliferation, differentiation, and tissue formation. The addition of heparin sodium enhanced tissue formation and organization, showing promising results for the regeneration of tendon total ruptures. Principio del formularioThis work was supported by the Spanish State Research Agency (AEI) under grant No CPP2021-008754. The authors would like to thank their partners in the project, which are in charge of the synthesis of heparin sodium and acrylated-WBPUs

Introduction. The arch of the foot has been described as a truss where the plantar fascia (PF) acts as the tensile element. Its role in maintaining the arch has likely been underestimated because it only rarely torn in patients with progressive collapsing foot deformity (PCFD). We hypothesized that elongation of the plantar fascia would be a necessary and sufficient precursor of arch collapse. Method. We used a validated finite element model of the foot reconstructed from CT scan of a female cadaver. Isolated and combined simulated ligament transection models were created for each combination of the ligaments. A collapsed foot model was created by simulated transection of all the arch supporting ligaments and unloading of the posterior tibial tendon. Foot alignment angles, changes in force and displacement within each of the ligaments were compared between the intact, isolated ligament transection, and complete collapse conditions. Result. Isolated release of the PF did not cause deformity, but lead to increased force in the long (142%) and short plantar (156%), deltoid (45%), and spring ligaments (60%). The PF was the structure most able to prevent arch collapse and played a secondary role in preventing hindfoot valgus and forefoot abduction deformities. Arch collapse was associated with substantial attenuation of the spring (strain= 41%) and interosseous talocalcaneal ligaments (strain= 27%), but only a small amount in the plantar fascia (strain= 10%). Conclusion. Isolated PF release did not cause arch collapse, but arch collapse could not occur without at least 10% elongation of the PF. Simulated transection of the PF led to substantial increase in the force in the other arch supporting ligaments, putting the foot at risk of arch collapse over time. Chronic degeneration of the PF leading to plantar fasciitis may be an early sign of impending PCFD

Introduction. PIEZO mechanoreceptors are increasingly recognized to play critical roles in fundamental physiological processes like proprioception, touch, or tendon biomechanics. However, their gating mechanisms and downstream signaling are still not completely understood, mainly due to the lack of effective tools to probe these processes. Here, we developed new tailor-made nanoswitches enabling wireless targeted actuation on PIEZO1 by combining molecular imprinting concepts with magnetic systems. Method. Two epitopes from functionally relevant domains of PIEZO1 were rationally selected in silico and used as templates for synthesizing molecularly imprinted nanoparticles (MINPs). Highly-responsive superparamagnetic zinc-doped iron oxide nanoparticles were incorporated into MINPs to grant them magnetic responsiveness. Endothelial cells (ECs) and adipose tissue-derived stem cells (ASCs) incubated with each type of MINP were cultured under or without the application of cyclical magnetomechanical stimulation. Downstream effects of PIEZO1 actuation on cell mechanotransduction signaling and stem cell fate were screened by analyzing gene expression profiles. Result. Nanoswitches showed sub-nanomolar affinity for their respective epitope, binding PIEZO1-expressing ECs similarly to antibodies. Expression of genes downstream of PIEZO1 activity significantly changed after magnetomechanical stimulation, demonstrating that nanoswitches can transduce this stimulus directly to PIEZO1 mechanoreceptors. Moreover, this wireless actuation system proved effective for modulating the expression of genes related to musculoskeletal differentiation pathways in ASCs, with RNA-sequencing showing pronounced shifts in extracellular matrix organization, signal transduction, or collagen biosynthesis and modification. Importantly, targeting each epitope led to different signaling effects, implying distinct roles for each domain in the sophisticated function of these channels. Conclusion. This innovative wireless actuation technology provides a promising approach for dissecting PIEZO-mediated mechanobiology and suggests potential therapeutic applications targeting PIEZO1 in regenerative medicine for mechanosensitive tissues like tendon. Acknowledgements. EU's Horizon 2020 ERC under grant No. 772817 and Horizon Europe under grant No. 101069302; FCT/MCTES for PD/BD/143039/2018, COVID/BD/153025/2022, 10.54499/2020.03410.CEECIND/CP1600/CT0013, 10.54499/2022.05526.PTDC, 10.54499/UIDB/50026/2020, 10.54499/UIDP/50026/2020, and 10.54499/LA/P/0050/2020

Introduction. Distal triceps tendon rupture is related to high complication rates with up to 25% failures. Elbow stiffness is another severe complication, as the traditional approach considers prolonged immobilization to ensure tendon healing. Recently a dynamic high-strength suture tape was designed, implementing a silicone-infused core for braid shortening and preventing repair elongation during mobilization, thus maintaining constant tissue approximation. The aim of this study was to biomechanically compare the novel dynamic tape versus a conventional high-strength suture tape in a human cadaveric distal triceps tendon rupture repair model. Method. Sixteen paired arms from eight donors were used. Distal triceps tendon rupture tenotomies and repairs were performed via the crossed transosseous locking Krackow stitch technique for anatomic footprint repair using either conventional suture tape (ST) or novel dynamic tape (DT). A postoperative protocol mimicking intense early rehabilitation was simulated, by a 9-day, 300-cycle daily mobilization under 120N pulling force followed by a final destructive test. Result. Significant differences were identified between the groups regarding the temporal progression of the displacement in the distal, intermediate, and proximal tendon aspects, p<0.001. DT demonstrated significantly less displacement compared to ST (4.6±1.2mm versus 7.8±2.1mm) and higher load to failure (637±113N versus 341±230N), p≤0.037. DT retracted 0.95±1.95mm after each 24-hour rest period and withstood the whole cyclic loading sequence without failure. In contrast, ST failed early in three specimens. Conclusion. From a biomechanical perspective, DT revealed lower tendon displacement and greater resistance in load to failure over ST during simulated daily mobilization, suggesting its potential for earlier elbow mobilization and prevention of postoperative elbow stiffness

Introduction. Supraspinatus tears comprise most rotator cuff injuries, the leading cause of shoulder pain and an increasing problem with ageing populations. Surgical repair of considerable or persistent damages is customary, although not invariably successful. Tissue engineering presents a promising alternative to generate functional tissue constructs with improved healing capacities. This study explores tendon tissue constructs’ culture in a platform providing physiological mechanical stimulation and reports on the effect of different loading regimes on the viability of human tendon cells. Method. Porcine decellularized tendon scaffolds were fixed into flexible, self-contained bioreactor chambers, seeded with human tenocytes, allocated in triplicates to either static control, low (15±0.8Newtons [N]), medium (26±0.5N), or high (49±2.1N)-force-regime groups, connected to a perfusion system and cultured under standard conditions. A humanoid robotic arm provided 30-minute adduction/abduction stimulation to chambers daily over a week. A metabolic activity assay served to assess cell viability at four time points. Statistical significance = p<0.05. Result. One day after beginning mechanical stimulation, chambers in the medium and high-force regimes displayed a rise in metabolic activity by 3% and 5%, respectively. By the last experimental day, all mechanical stimulation regimes had induced an augment in cell viability (15%, 57% and 39% with low, medium, and high loads, respectively) matched against the static controls. Compared to all other conditions, the medium-force regime prompted an increased relative change in metabolic activity for every time point set against day one (p<0.05). Conclusion. Human tenocytes’ viability reflected by metabolic activity in a physiologically relevant bioreactor system is enhanced by loading forces around 25N when mechanically stimulating using adduction/abduction motions. Knowing the most favourable load regime to stimulate tenocyte growth has informed the ongoing exploration of the distinctive effect of different motions on tendon regeneration towards engineering tissue grafts. This work was supported by the Engineering and Physical Sciences Research Council EP/S003509/1

Introduction. Patellar tendinopathy is a highly prevalent clinical diagnosis supported by ultrasound changes. Numerous interventions are targeted at improving both symptoms and structure of dysfunctional tendons, however little is known of the diagnostic value in a changing ultrasound profile whilst patient reported outcome measures determine recovery. The aim of this study was to assess if change in ultrasound measure is congruent with change in Victorian Institute of Sport Assessment – Patella (VISA-P) score and therefore indicates the use of using ultrasound to assess patellar tendinopathy during symptom change. Method. Four databases (PubMed, Web of Science, Embase, Cinahl) were search in January 2014. Studies selected contained ultrasound and VISA-P scores from ≥ 2 type points. All included studies were quality assessed depending on type and available data underwent meta-analysis. Result. 10 papers of varying study type, of limited to high quality, were synthesised. Meta-analysis indicated that change in ultrasound measure was not congruent with change in VISA-P score. Conclusion. The variation in study quality, along with significant heterogeneity of ultrasound measure outcomes and reporting may influence the congruency of the data, but the association between gradual structure change and varying vascularity with pain or function is questionable throughout tendinopathy literature

Introduction. Diabetes mellitus type 2 (DMT2) patients often develop Achilles tendon (AS) degeneration. The ZDF rat model is often used to study DMT2. Hence, this study investigated whether tenocytes isolated from diabetic and non diabetic ZDF rats respond differentially to normo- (NG) and hyperglycemic (HG) conditions in the presence of tumor necrosis (TNF)α. Method. AS tenocytes isolated from adult diabetic (fa/fa) or lean (fa/+) Zucker Diabetic Fatty (ZDF) rats were treated with 10 ng/mL TNFα either under NG or HG conditions (1 g/L versus 4.5 g/L glucose). Tendons were characterized histopathologically using Movin score. Tenocyte survival, metabolic activity, gene and/or protein expression of the main tendon extracellular matrix (ECM) component collagen type 1, the myofibroblast marker alpha smooth muscle actin (αSMA, Acta2), complement regulatory factors, the antioxidant defense enzyme heme oxygenase-1 (Hmox1), suppressors of cytokine signaling (Socs)1 and Soc3 were analyzed. Result. Tendons of diabetic rats showed significantly higher Movin score values suggesting tendon degeneration. Tenocyte vitality remained high, but metabolic activity was impaired by HG conditions, irrespectively of tenocyte origin. Higher amounts of αSMA were visualized in tendons/cells of diabetic rats or those exposed to TNFα. Collagen type 1 protein and gene expression was suppressed by TNFα (NG), but only in cells of non diabetic animals. The anaphylatoxin receptor C3aR was higher expressed in tenocytes from diabetic animals. CD46 was suppressed by TNFα (NG) in cells of diabetic rats. Hmox1, Socs1 and Socs3 were induced by HG, but only in tenocytes of diabetic rats (4 h). Conclusion. The response of tenocytes to TNFα depends on glucose supply and cell origin suggesting their irreversible impairment in DMT2

Introduction. The Achilles tendon is the thickest and strongest tendon in the human body. Even though the tendon is so strong, it is one of the most frequently injured tendons. Treatment of patients after rupture is planned conservatively and surgically. Conservative treatment is generally applied to elderly patients with sedentary lives. If the treatment is surgical, it can be planned as open surgery or percutaneous surgery. In our study with rabbits, we wrapped a membrane made of plga (polylactic-co-glycolic acid) nanotubes impregnated with type 1 collagen around the tendon in rabbits that underwent open Achilles tendon repair surgery. After surgery, biomechanical and histological tests were performed on the tendons. Method. In the study consisting of 24 rabbits, 2 groups were created by random distribution. In the study group, after the Achilles tendon rupture was created, a type 1 collagen-impregnated plga-based membrane was placed around the tendon after the repair of 1 modified Kesslerr suture. In the control group, after the Achilles tendon rupture was created, 1 modified Kessler suture and Tendon repair was performed with the application of 3 primary sutures. At the end of the 6th week of the study, the rabbits in 2 groups were randomly distributed and histological examination was performed. Additionally, biomechanical testing was performed. Bonar and Movın scoring were used in histological examinations. Result. As a result of biomechanical tests, it was seen that the resistance of the tendon against rupture was higher in the study group than in the control group. In addition, it was observed that the tendon rupture time was longer in the study group than in the control group. Histological examinations gave supportive results from biomechanical tests. Conclusion. We think that the use of collagen-impregnated plga-based nanotubes in the surgical treatment of Achilles tendon ruptures has a positive healing effect. Although we think that the return to normal life after surgery may be faster, we believe that more clinical studies are needed

Introduction. Healthy tendons are mainly composed of aligned collagen hierarchically organized from collagen fibrils to fiber bundles with a scarce cellular population mainly composed of tenocytes and tendon stem/progenitor cells. However, injured tendon acquires a fibrotic state characterized by a loss of ECM alignment and increased cellularization. The lack of reliable 3D models that recreate the organization and microenvironment of healthy and diseased tendons is one of the main obstacles faced by the scientific community. Method. To recreate the architecture of healthy and diseased tendons, electrospun nanofiber scaffolds with anisotropic and isotropic nanotopography were developed. These scaffolds were coated with a shell consisting of cell-laden hydrogels encapsulating human adipose-derived stem cells (hASCs) to include the living component. To show the versatility of the system, extracellular vesicles (EVs) were encapsulated in the hydrogel as biological cues. The living fibers were characterized by microscopy and morphological analysis. The morphology and phenotype of cells was evaluated using microscopy, gene expression analysis and immunostainings for tendon markers. Results. Scaffolds mimicked the native hierarchical structure of tendons and size of tendon fascicles. hASCs showed high elongation and cytoskeleton anisotropic organization, typical of tenocytes. Moreover, the bioengineered living fibers supported the tenogenic differentiation of stem cells over time, as indicated by the sustained expression of tenogenic and extracellular matrix markers. Finally, the hydrogel layer acted not only as a hydrated biomimetic environment adequate for cell encapsulation but also as a carrier and delivery system of EVs to cells, which improved their tenogenic commitment. Conclusion. We bioengineered composite living fibers made of hierarchically organized electrospun fibers, coated with hydrogel encapsulating hASCs and biofunctional EVs. These provide an in vitro system to recreate tendon, allowing for the study of the effects of biophysical cues in tendon microenvironments and the influence of biologics on cells behavior. Acknowledgments. CP21/00136, PI22/01686, CA22170, 10.54499/2020.03410.CEECIND/CP1600/CT0013, 10.54499/2022.05526.PTDC

Introduction. Tendinopathies represent a significant health burden, causing inflammation, pain, and reducing quality of life. The pivotal role of macrophages (Mφ) characterized by their ability to differentiate into proinflammatory (M1) or anti-inflammatory (M2) phenotypes depending on the microenvironment, has gained significant interest in tissue inflammation research. Additionally, existing literature states that the interplay between tenocytes and immune cells during inflammation involves unidentified soluble factors (SF). This study aimed to investigate the effect of extracellular vesicles (EVs) and SF derived from polarized Mφ on tendon cells to provide deeper insights of their potential therapeutic applications in the context of inflammation. Method. Human monocytes were isolated from blood donor buffy coats and differentiated into M1, M2, and hybrid M1/M2 phenotypes. Subsequently, EVs were isolated from the conditioned media from polarized Mφ and comprehensively characterized. In parallel, the elution media containing SF was collected. Furthermore, the EVs and SF were released independently onto tenocytes from human donors, previously induced with IL-1β to simulate an inflammatory environment. Finally, mRNA levels of tendon-related markers were evaluated by qPCR after the exposure to these EVs and SF. Result. Notably, the study found that the viability of the cells was not affected by the exposure to EVs nor SF, indicating their potential safety for therapeutic use. Moreover, the mRNA content of tendon-derived cells was evaluated following exposure to Mφ-EVs and SF revealing alterations in gene expression. Interestingly, a significant increase in the expression of tenomodulin was observed in tendon cells treated with Mφ-EVs. Conclusion. These results mark a significant advancement in understanding the interplay between Mφ and tenocytes at a molecular level. To fully understand the underlying causes of Mφ-EVs effects, and its potential clinical application in tendon inflammatory diseases, further comprehensive research is required. Acknowledgments. Carlos III Health Institute and the European Social Fund for contract CP21/00136 and project PI22/01686

Introduction. Treatment strategies for irreparable Massive Rotator Cuff Tears (MRCTs) are debatable, especially for younger, active patients. Superior Capsular Reconstruction (SCR) acts as a static stabilizer, while Lower Trapezius Transfer (LTT) serves as a dynamic stabilizer. This study compares the biomechanical effectiveness of SCR and LTT, hypothesizing that their combination will enhance shoulder kinematics. Methods. Eight human shoulders from donors aged 55-75 (mean = 63.75 years), balanced for gender, averaging 219.5 lbs, were used. Rotator cuff and deltoid tendons were connected to force sensors through a pulley system, with the deltoid linked to a servohydraulic motor for dynamic force measurement. Results. From intact to MRCT, deltoid force was reduced by 28% (p = 0.023). LTT increased deltoid force by 27.25 (p = 0.166). SCR decreased deltoid force by 34% (p = 0.208). Combining LTT with SCR increased deltoid force by 32.57% compared to SCR (p = 0.023) and decreased it by 13.6% compared to LTT alone (p = 0.017). Combined LTT and SCR reduced deltoid force by 20.9% from the control (p = 0.001). Subacromial contact pressure rose by 15% in MRCT over intact, but LTT decreased it by 7.6%, achieving nearly 50% correction. SCR increased subacromial space volume, raising pressure by 6.5%. The humeral head translation (HHT) increases with MRCT, reaching 3.33 mm (SD = 0.95) at 0 degrees, compared to 2.24 mm (SD = 0.78) in the intact. LTT and the combined LTT + SCR significantly reduce HHT, with combined LTT + SCR achieving HHT of 2.24 mm (SD = 0.63) at 0 degrees, comparable to the control. Conclusion. Notable changes in deltoid force were observed. LTT outperformed the combined SCR and LTT in reducing deltoid force and subacromial peak pressure. Both SCR and LTT corrected HTT, with LTT being more effective. However, combining SCR and LTT optimally corrected HHT

Aims

The aim of this study was to compare patient-reported outcomes (PROMs) following isolated anterior cruciate ligament reconstruction (ACLR), with those following ACLR and concomitant meniscal resection or repair.

Aims. Reconstruction after osteoarticular resection of the proximal ulna for tumours is technically difficult and little has been written about the options that are available. We report a series of four patients who underwent radial neck to humeral trochlea transposition arthroplasty following proximal ulnar osteoarticular resection. Methods. Between July 2020 and July 2022, four patients with primary bone tumours of the ulna underwent radial neck to humeral trochlea transposition arthroplasty. Their mean age was 28 years (12 to 41). The functional outcome was assessed using the range of motion (ROM) of the elbow, rotation of the forearm and stability of the elbow, the Musculoskeletal Tumor Society score (MSTS), and the nine-item abbreviated version of the Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH-9) score. Results. All patients were available for follow-up at a mean of 33 months (25 to 43) and were disease-free. The mean flexion arc was 0° to 105°. Three patients had complications. One had neuropraxia of the ulnar nerve. The symptoms resolved after three months. In one patient, the screw used for fixation of the triceps tendon became exposed and was removed, six months postoperatively. One patient with wound dehiscence required a local flap for soft-tissue cover, four months postoperatively. At a mean follow-up of 33 months (25 to 43), the mean flexion arc was 0° to 105°. All patients had full supination (85°) but none had any pronation. The mean MSTS score was 23.5 (23 to 24) and mean QuickDASH-9 score was 26.13 (16.5 to 35.75). Three patients had varus-valgus instability on examination, although only one had a sense of instability while working. Conclusion. Radial neck to humeral trochlea transposition offers a satisfactory and cost-effective biological reconstructive option after osteoarticular resection of the proximal ulna, in the short term. It provides good elbow function and, being a biological reconstruction option using native bone, is likely to provide long-term stability and durability. Cite this article: Bone Joint J 2024;106-B(11):1301–1305

Aims

We aimed to compare reoperations following distal radial fractures (DRFs) managed with early fixation versus delayed fixation following initial closed reduction (CR).

Aims

Treatment of high-grade limb bone sarcoma that invades a joint requires en bloc extra-articular excision. MRI can demonstrate joint invasion but is frequently inconclusive, and its predictive value is unknown. We evaluated the diagnostic accuracy of direct and indirect radiological signs of intra-articular tumour extension and the performance characteristics of MRI findings of intra-articular tumour extension.

Aims

This study aimed to investigate the optimal sagittal positioning of the uncemented femoral component in total knee arthroplasty to minimize the risk of aseptic loosening and periprosthetic fracture.