Aims: Fracture nonunion represents a major complication in orthopaedic surgery, occurring in 5% to 10% of fracture patients. Fracture nonunions are associated with pain and loss of function, and lead to a substantial socioeconomic burden. The present retrospective cohort study analyzed direct and indirect costs and length of hospital stay, number of surgical procedures, and hospital (re-)admissions of nonunion patients.Methods: Data from 18- to 65-year-old patients surgically treated for lower limb fractures and nonunions in a German level I trauma centre between 2012 and 2018 were analyzed. A total of 193 patients with nonunion were included, and 2,511 patients with fractures served as the control group. Direct costs were calculated using reimbursement according to the diagnosis-related group (DRG). Indirect costs were calculated including daily sickness allowance and productivity loss.Results: The median healing time of nonunion patients was 45 weeks. Treatment expenses showed a 2.6-fold increase in direct costs, a 3.3-fold increase in indirect costs, and a 3.3-fold increase in total costs for nonunion patients compared to the control group. As every patient with a nonunion suffered from a fracture prior to nonunion treatment, costs were calculated by adding the median direct costs of €10,487 (IQR 9,173 to 15,262), median daily sickness allowance of €23,046 (IQR 14,892 to 36,264), median productivity loss of €85,714 (IQR 60,949 to 126,650), and median total socioeconomic burden of €123,334 (IQR 88,630 to 176,329).Conclusion: Nonunions not only pose a significant burden on the injured individual and on healthcare systems, but also have a substantial socioeconomic impact. High direct and indirect costs illustrate that healing complications need to be detected and addressed as early as possible.Cite this article: Bone Joint Res 2025;14(4):1–10.

Background/Objectives: Using a patient’s own wearable sensor to obtain objective outcome data is a growing field in trauma allowing for the assessment of the recovery trajectory back toward the pre-injury performance. The aim of this study was to analyze recruitment characteristics and reasons for declined study participation in an orthopedic trauma study that measures postoperative recovery using wearables. Methods: Data from 225 patients screened for participation in a wearable-sensor-based outcome study were assessed. The influence of age, sex and injury location on study participation was analyzed. Reasons for patients declining to participate were investigated from the screening log. Availability and type of sensor system in patients agreeing to participate were analyzed. Results: Overall, 48% of patients agreed to participate. Age was the only significantly different factor between agreeing and declining patients (p < 0.05). The main reasons to decline study participation were technical difficulties with or inability to use the wearable device, lack of availability of a wearable, and general disinterest to participate in a study. Notably, 7% declined due to data safety concerns. Conclusions: The results show that age, availability of the wearable, and technical ability to use a wearable are the main obstacles impacting objective outcome measurement using a personal wearable device. In studies including geriatric patients, a dedicated device requiring no patient handling can be a valid option to improve enrollment. Understanding the reasons for declining to participate will facilitate the development of future sensor-based studies to address concerns of technical handling through alternative means of data harvesting and increase the inclusion rate. These outcomes will guide future study designs to optimize patient inclusion.

With a gradually increasing elderly population, the treatment of geriatric patients represents a major challenge for trauma and reconstructive surgery. Although, it is well established that aging affects bone metabolism, it is still controversial if aging impairs bone healing. Accordingly, we investigated fracture healing in young adult (3–4 months) and aged (16–18 months) CD-1 mice using a stable closed femoral fracture model. Bone healing was analyzed by radiographic, biomechanical and histological analysis at 1, 2, 3, 4 and 5 weeks after fracture. Our results demonstrated an increased callus diameter to femoral diameter ratio in aged animals at later time points of fracture healing when compared to young adult mice. Moreover, our biomechanical analysis revealed a significantly decreased bending stiffness at 3 and 4 weeks after fracture in aged animals. In contrast, at 5 weeks after fracture, the analysis showed no significant difference in bending stiffness between the two study groups. Additional histological analysis showed a delayed endochondral ossification in aged animals as well as a higher amounts of fibrous tissue at early healing time points. These findings indicate a delayed process of callus remodeling in aged CD-1 mice, resulting in a delayed fracture healing when compared to young adult animals. However, the overall healing capacity of the fractured femora was not affected by aging.

Background: The healing potential of a fracture is determined by mechanical and biological factors. Simulation-based workflows can help assess these factors to assist in predicting non-unions. The aim of this study was the introduction of two use cases for a novel patient-specific simulation workflow based on clinically available information. Methods: The used software is an extension of the “Ulm Bone Healing model” and was applied in two cases with non-union development after fracture fixation to show its principal feasibility. The clinical and radiographic information, starting from initial treatment, were used to feed the simulation process. Results: The simulation predicted non-union development and axial deviation in a mechanically driven non-union. In the case of a biological non-union, a slow, incomplete healing course was correctly identified. However, the time offset in callus bridging was discordant between the simulation and the distinctly slower healing response in the clinical case. Conclusions: The simulation workflow presented in the two clinical use cases allowed for the identification of fractures at risk for impending non-union immediately after the initial fixation based on available clinical and radiographic information. Further validation in a large non-union cohort is needed to increase the model’s precision, especially in biologically challenging cases, and show its validity as a screening instrument.

Diabetes represents a major risk factor for impaired fracture healing. Type 2 diabetes mellitus is a growing epidemic worldwide, hence an increase in diabetes-related complications in fracture healing can be expected. However, the underlying mechanisms are not yet completely understood. Different mouse models are used in preclinical trauma research for fracture healing under diabetic conditions. The present review elucidates and evaluates the characteristics of state-of-the-art murine diabetic fracture healing models. Three major categories of murine models were identified: Streptozotocin-induced diabetes models, diet-induced diabetes models, and transgenic diabetes models. They all have specific advantages and limitations and affect bone physiology and fracture healing differently. The studies differed widely in their diabetic and fracture healing models and the chosen models were evaluated and discussed, raising concerns in the comparability of the current literature. Researchers should be aware of the presented advantages and limitations when choosing a murine diabetes model. Given the rapid increase in type II diabetics worldwide, our review found that there are a lack of models that sufficiently mimic the development of type II diabetes in adult patients over the years. We suggest that a model with a high-fat diet that accounts for 60% of the daily calorie intake over a period of at least 12 weeks provides the most accurate representation.

The incidence of non-union following distal femur fractures is high. Management of persis-tent non-unions is challenging, often requiring multiple revision surgeries, thereby increasing patient morbidity and socioeconomic burden. Identifying patients at high risk for persistent non-union after revision is therefore crucial. The LEG NUI Score was originally developed to predict the need for early intervention following primary fixation of distal femur fractures. This study aimed to evaluate the LEG NUI Score's ability to predict the need for further revision surgery in a cohort of patients with established distal femur non-union undergoing their index revision procedure. 45 patients with complete clinical data were identified from a non-union database. The LEG NUI Score was calculated for the index revision procedure and assessed in relation to the healing out-come of the revision treatment. Comparative statistics and test characteristics were assessed, as well as a receiver operator characteristic analysis was performed. Only patients with uneventful healing after the first treatment were considered healed for the score calculation. Patients requiring more than one surgery, including second step masquelet were considered non-healers. The union rate (healed non-unions) after the first non-union revision surgery was 55.5 %. 24.4 % of patients had an infected non-union. The average LEG NUI Score in patients with non-union healing was significantly lower than non-healing patients (3.36 ± 1.80 vs. 4.90 ± 1.21; p < 0.05). The AUC in the ROC Analysis was 0.755. The LEG NUI Score shows potential applicability in the setting of revision surgery for established distal femur non-unions. Calculating the score may help surgeons identifying patients at in-creased risk for requiring subsequent surgical procedures, thus warranting closer postoperative surveillance. Further validation in larger cohorts is required to fully elucidate its clinical utility in this context. Level III, Retrospective Cohort Study.