Citations

Abstract Background Central venous catheterization (CVC) is a fundamental procedural competency in pulmonary and critical care medicine (PCCM). Although commercially available task trainers are effective for teaching CVC placement, their high cost and logistical requirements can limit access to repeated practice. Objective To evaluate learner and faculty perceptions and usability of a newly developed CVC simulation model compared with a standard commercial task trainer and detail the technical report of the novel model’s construction. Methods We conducted a prospective educational evaluation during the PCCM CVC workshop. Participants practiced CVC placement with both the standard commercial trainer and a locally constructed simulation model developed at our institution. Teaching faculty were asked to evaluate both models from an instructional standpoint. Results Eighteen participants (15 PCCM 1st year fellows and 3 faculty instructors) evaluated the novel CVC simulation model. All fellows (n = 15, 100%) preferred the new model over a standard commercial model, with 14 (93%) reporting improved understanding of CVC insertion steps and 11 (73%) noting ease of ultrasound landmark identification. All fellows (n = 15, 100%) endorsed inclusion of the model in future workshops. Additionally, faculty instructors preferred the novel model for teaching (n = 3, 100%). All faculty supported future use of the model. The initial model development cost was approximately $288.96 with most materials’ reusable. Conclusions The novel task-aligned CVC simulation model offers a realistic, reusable, and cost-effective alternative to commercial simulators, with high learner and faculty preference and strong educational value. Its functional alignment supports integration into fellowship training, with future studies needed to assess objective skill acquisition and retention.

Aims Reliable assessment of joint stiffness is essential for studying arthrofibrosis in preclinical animal models. This study presents a new dedicated biomechanics device for measuring knee stiffness in mouse, rat, and rabbit models of arthrofibrosis, with the aim of validating its performance and comparing it to a previously validated device. Methods The new system integrates a torque load cell, stepper motor, and absolute encoder in a through-hole, unified configuration for precise continuous torque-angle measurement, with custom limb brackets ensuring species-specific alignment at the joint’s centre of rotation. To validate this device and compare it to a previously validated device, arthrofibrosis was induced using established models of extra-articular immobilization in mice and intra-articular violation with immobilization in rats and rabbits, followed by defined remobilization periods. Torque-angle curves were recorded ex vivo across species-specific torque ranges, and measurement variability between the new and a previous validated device was statistically compared using Brown-Forsythe’s test. Results The onset of hyperextension in contralateral limbs occurred at mean angles of 152.4° (mice), 154.4° (rats), and 152.8° (rabbits), and at maximum torque, mean flexion angles were 79.2°, 87.3°, and 140.5°, respectively. No significant differences in measurement variability were observed between devices across all species. Conclusion These findings demonstrate that our new device provides reproducible torque-angle data while maintaining the statistical robustness of the previous device and offering improved mechanical design and operational standardization. By enabling standardized, cross-species joint stiffness quantification, this platform improves cross-study comparability and strengthens the translational reliability of preclinical arthrofibrosis research. Cite this article: Bone Joint Res 2026;15(6):716–725.

Aims Total elbow arthroplasty (TEA) has shown favourable outcomes in the management of severely comminuted distal humeral fractures in low-demand elderly patients, leading to its increased use in recent years. Less is known about the outcomes of TEA when used for the failure of either internal fixation or conservative management, particularly whether not performing TEA acutely influences the options for further management if fixation fails. This systematic review aimed to assess the clinical and functional outcomes following TEA when used for the post-traumatic sequelae of a distal humeral fracture, and to compare these outcomes with those in patients with a distal humeral fracture who undergo TEA acutely. Methods MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Scopus databases were searched from January 2000 to September 2024 for studies reporting complications, reoperations, the range of motion of the elbow, or functional outcomes following the use of TEA in the management of the post-traumatic sequelae of distal humeral fractures, including those due to failed fixation, nonunion, and post-traumatic arthritis. Demographic and clinical data were collected, descriptive statistics were summarized, and meta-analyses were undertaken to compare the outcomes between salvage and acute TEA. Results A total of 16 studies were included, with a total of 380 patients who underwent salvage TEA and 251 who underwent TEA as the initial management. Salvage TEA was associated with a significantly higher overall risk of complications (odds ratio (OR) 2.5 (95% CI 1.0 to 5.9)), though the rate of reoperations did not differ from those who underwent TEA acutely (OR 1.4 (95% CI 0.8 to 2.4)). Pooled analyses revealed a similar postoperative range of flexion (mean difference (MD) -2.4° (95% CI -9.1 to 4.3)) and extension of the elbow (MD 1.1° (95% CI -2.3 to 4.5)) and pronation (MD 0.0° (95% CI -1.1 to 1.1)) and supination (MD -0.0° (95% CI -1.0 to 0.9)) of the forearm. However, salvage TEA showed significantly inferior functional outcomes, as assessed by the Mayo Elbow Performance Score (MD 9.7 (95% CI -18.8 to -0.6)). Conclusion These findings indicate that salvage TEA represents a viable option for the management of post-traumatic sequelae following the teatment of a distal humeral fracture, although patients who underwent salvage TEA had a significantly increased rate of complications and significantly inferior functional outcomes compared with those who underwent TEA acutely. Cite this article: Bone Joint J 2026;108-B(1):21–29.

Aims Arthrofibrosis affects a notable percentage of patients after total knee arthroplasty (TKA). Elevated serum mast cell tryptase (SMCT) levels have been linked to fibrosis, suggesting that SMCT could serve as a biomarker for arthrofibrosis. As such, the aims of this study were to assess SMCT levels in TKA patients, and their possible association with arthrofibrosis and clinical outcomes in a prospective clinical trial. Methods We conducted a prospective study involving 219 patients undergoing primary TKA at a single academic medical centre between January 2018 and December 2022. SMCT levels were measured preoperatively, immediately postoperatively, and at six weeks, three months, and one year postoperatively. Secondary outcomes included revision rates, complications, and Knee Society Scores (KSSs). Allergic and inflammatory conditions were assessed for their influence on SMCT levels. Results At one year postoperatively, eight patients had developed arthrofibrosis (4%), and three (1.5%) had undergone manipulation under anaesthesia. The mean preoperative SMCT level was 5.6 µg/L (SD 3.4), which decreased significantly to 4.1 µg/L (SD 2.7) immediately postoperatively (p < 0.001). At six weeks the mean SMCT level was 6.4 µg/l (SD 4.1), and was 6.1 µg/l at both three months (SD 4.1) and one year (SD 4.0). Elevated preoperative SMCT levels were not significantly associated with the risk of arthrofibrosis development (OR 3; p = 0.370), nor were immediate postoperative levels (OR 2; p = 0.754) or those at six weeks (OR 1; p = 0.989). Of note, elevated SMCT levels at three months (OR 5; 95% CI 0.4 to 64; p = 0.191) and one year (OR 13; 95% CI 1 to 232; p = 0.077) trended toward an increased risk of arthrofibrosis development, without reaching significance. Conclusion In patients undergoing TKA, with the numbers included in this study, there was no significant difference in SMCT levels between patients who did and did not develop arthrofibrosis at any timepoint. However, there was a trend towards elevated SMCT levels at three months and one year in those who developed arthrofibrosis, which merits further study. Cite this article: Bone Joint Res 2025;14(11):1045–1052.

Arthrofibrosis is a common complication following total knee arthroplasty and is the result of a dysregulated immuno-inflammatory cascade, which culminates in excessive scar deposition by myofibroblasts within the knee joint. Pharmacotherapies for arthrofibrosis are limited, with treatment reliant on manipulation under anesthesia or lysis of adhesions with or without component revision. Bupivacaine (a local anesthetic) and meloxicam (a nonsteroidal anti-inflammatory drug) combination therapy may exert antifibrotic properties by limiting inflammatory cell recruitment and the subsequent release of profibrotic cytokines. The purpose of this study was to evaluate the effects of this combination therapy in a rabbit model of arthrofibrosis by evaluating live and postsacrifice knee biomechanics and gene expression of posterior knee capsule tissue. Forty New Zealand white rabbits were equally divided into two experimental groups and prospectively studied to assess knee passive extension angles (PEA), terminal posterior capsular stiffness, and the inflammatory milieu of the posterior knee joint capsule. Experimental limbs with and without combination therapy showed similar live PEAs and terminal posterior capsular stiffness, with no significant differences between the groups. Gene expression analysis, however, revealed significant reduction in inflammatory genes but not profibrotic genes. In summary, bupivacaine and meloxicam combination therapy did not exert antifibrotic effects in a rabbit model of arthrofibrosis but significantly reduced the expression of inflammatory markers in the local environment of the posterior capsule.

Abstract The stress environment of the extracellular matrix of the supraspinatus tendon, including the stress distribution and concentration, was evaluated by using a finite element model. Stress riser was found around the insertion at the articular side of the tendon. Compressive and shear stresses were observed at the articular side which corresponded to the region associated with fibrocartilaginous matrix. This area corresponded well with the critical zone of potential tear observed clinically.

Diabetic foot ulcers (DFUs) are common complications of suboptimally controlled diabetes, characterised by non-healing, high morbidity, infection, recurrence (40–50%) and mortality. Ultrasonic debridement technology has been used for >30 years to treat cataracts safely and effectively, and animal studies have suggested that ultrasound debridement stimulates collagen turnover. This technology was applied in developing a system for soft tissue removal in tendons and elsewhere, with intended use in the elbow, knee, ankle, foot and shoulder. It was then modified for the treatment of DFUs. In this study, the rationale behind using this technology is discussed, the procedural technique is described, and photographic examples of treatment outcomes presented.

AimsTo characterize the effects of varying experimental parameters of transforming growth factor-beta 1 (TGF-β1) in primary knee fibroblasts as an in vitro model of arthrofibrosis.MethodsPrimary knee fibroblasts were isolated from one patient undergoing primary total knee arthroplasty (TKA) and one patient undergoing revision TKA for arthrofibrosis, respectively. Fibroblasts were stimulated with varying concentrations and durations of the pro-fibrotic cytokine TGF-β1. Picrosirius red staining (PSR) was conducted to assess collagen deposition, and real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting were performed to determine cellular gene expression levels. A collagen gel contraction assay was used to assess TGF-β1-induced fibroblast contraction.ResultsIn our experiments, TGF-β1-mediated collagen deposition was consistent across a vast concentration range (0.5 to 40 ng/ml). While α-smooth muscle actin (ACTA2) protein levels and SMAD2 phosphorylation were induced by low concentrations (1 ng/ml), robust ACTA2 transcription required higher concentrations (5 ng/ml) of TGF-β1. Evaluation of TGF-β1-mediated cell and cytoskeletal contractility shows that in the measured fibroblasts, this process occurs within three hours following TGF-β1 administration. Of note, TGF-β1-differentiated myofibroblasts exhibited greater contractile properties than naïve fibroblasts in the presence of TGF-β1.ConclusionTaken together, this study elucidates key TGF-β1 experimental parameters that will inform the development and interpretation of in vitro models of arthrofibrosis.Cite this article: Bone Joint Res 2025;14(6):527–538.

Experimental analyses of knee joint contractures have traditionally utilized a 6-month rabbit model as the gold standard. However, this model is time-intensive and costly. The purpose of this study was to develop an abbreviated rabbit model of knee contractures and compare it to the well-established longer model. Twenty female New Zealand White rabbits were divided into two equal groups and prospectively studied to assess knee passive extension angles (PEA), contracture angles (CA), and terminal posterior capsular stiffness. Experimental knees were immobilized for either 4 weeks ( n = 10) with an 8-week remobilization period in the abbreviated model (i.e., 3 months) or for 8 weeks ( n = 10) with a 16-week remobilization period in the standard model (i.e., 6 months). PEAs were assessed at remobilization and several time points using differing vertical forces. At sacrifice, terminal biomechanical data were collected to assess posterior capsular stiffness. Analysis of PEAs in live animals at each torque value and time point demonstrated increased PEAs and decreased CAs in the 3-month abbreviated model as compared to the 6-month standard model. At sacrifice, biomechanical analysis demonstrated that the posterior capsules of the 3-month experimental limbs were significantly more stiff than the contralateral limb (2.4 vs. 0.05 Ncm/°, p < 0.0001), but significantly less stiff compared to the 6-month experimental limbs (2.4 vs. 4.7 Ncm/°, p < 0.0001). Our study suggests that the 6-month standard rabbit knee model of arthrofibrosis should continue to be used in the laboratory assessment of arthrofibrosis. However, the abbreviated model may be beneficial under selected experimental conditions.

AimsTo evaluate the role of autophagy in primary knee fibroblasts undergoing myofibroblast differentiation as an in vitro model of arthrofibrosis, a complication after total knee arthroplasty characterized by aberrant intra-articular scar tissue formation and limited range of motion.MethodsWe conducted a therapeutic screen of autophagic-modulating therapies in primary human knee fibroblasts undergoing transforming growth factor-beta 1 (TGF-β1)-mediated myofibroblast differentiation. Autophagy was induced pharmacologically with rapamycin or by amino acid deprivation. Picrosirius red staining was performed to quantify collagen deposition. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were conducted to evaluate fibrotic gene expression levels.ResultsRapamycin, an mTOR complex 1 (mTORC1) inhibitor and autophagy inducer, reduced TGF-β1-mediated collagen deposition. Interestingly, we simultaneously report that myofibrogenic genes, including ACTA2, were highly upregulated following rapamycin-TGF-β1 treatment. When autophagy was induced through amino acid deprivation, we demonstrated suppressed extracellular matrix levels, fibrotic gene expression (e.g. ACTA2), and SMAD2 phosphorylation levels in TGF-β1-stimulated fibroblasts.ConclusionOur findings demonstrate that the induction of cellular autophagy suppresses TGF-β1-induced collagen deposition in primary human knee fibroblasts. Taken together, these data suggest that cellular autophagy may be prophylactic against the pathogenesis of arthrofibrosis.Cite this article: Bone Joint Res 2025;14(4):328–337.