Search Results (5)

Background: Limb-salvage surgery using extendable distal femoral endoprostheses has become the standard reconstruction following tumor resection in skeletally immature patients, allowing continued growth and improved function. However, mechanical complications, particularly tibial pain, remain challenging and poorly understood. This study aimed to identify radiographic predictors of tibial pain and evaluate their potential utility in early risk detection. Methods: A retrospective cohort study was conducted of 29 skeletally immature patients (mean age 10.4 years) who underwent expandable distal femoral endoprosthetic replacement between 2008 and 2018 at a tertiary orthopedic oncology center. Standardized radiographs were analyzed at 6 months and final follow-up (mean 75 months) to assess cortical thickness, stem-to-cortex distances, stem migration, stress shielding, pedestal formation, and periosteal reaction. Associations between radiographic parameters and tibial pain were assessed using multivariable logistic regression, t-tests, and chi-square analyses. Results: Seventeen patients (58.6%) developed activity-limiting tibial pain requiring analgesics, as documented during follow-up. Mean medial and lateral cortical thickness increased from 3.0 mm and 3.4 mm to 4.1 mm and 5.1 mm, respectively. The logistic regression model demonstrated strong explanatory power (Pseudo R² = 0.57, p = 0.004). Medial cortical thickness at last follow-up was the only significant independent predictor of tibial pain (p = 0.042), and was significantly associated with tibial pain. Patients with tibial pain exhibited greater medial cortical thickening (p < 0.001). Stem migration (φ = 0.421, p = 0.065), stress shielding (φ = 0.476, p = 0.044), pedestal formation (φ = 0.608, p = 0.004), and periosteal reaction (φ = 0.569, p = 0.008) were also associated with pain. Conclusions: Medial cortical hypertrophy emerged as a potential radiographic biomarker for tibial pain. after expandable distal femoral endoprosthesis in growing patients. The findings suggest that cortical remodeling, stress shielding, and pedestal formation collectively reflect stem micromotion and bone adaptation. Early radiographic surveillance of these parameters warrants further investigation in prospective studies to determine their clinical utility. Larger multicenter studies are warranted to validate these predictors and refine postoperative monitoring protocols. Full article

This study presents a computational framework for the topology optimization of a patient-specific femoral component used in the total knee endoprosthesis. The motivation stems from the growing need to enhance implant longevity and biomechanical compatibility by optimizing internal structural design according to physiological loading conditions. A finite element–based density optimization method was employed to determine the optimal material distribution within the femoral component while maintaining anatomical geometry and functional constraints. The model was developed using realistic boundary conditions derived from knee joint mechanics, and the resulting design was compared with a conventional reference geometry. The optimized configuration exhibited more uniform stress distribution, reduced peak von Mises stresses, and improved mass efficiency without compromising mechanical stiffness. These findings demonstrate that the proposed method can significantly improve the structural performance and reliability of knee prostheses. The study concludes that integrating patient-specific modeling with topology optimization offers a promising pathway for developing advanced, individualized orthopedic implants and supports future experimental validation through 3D printing and biomechanical testing. Full article

Diagnostic imaging has become an integral part of the healthcare system. In recent years, scientists around the world have been working on artificial intelligence-based tools that help in achieving better and faster diagnoses. Their accuracy is crucial for successful treatment, especially for imaging diagnostics. This study used a deep convolutional neural network to detect four categories of objects on digital chest X-ray images. The data were obtained from the publicly available National Institutes of Health (NIH) Chest X-ray (CXR) Dataset. In total, 112,120 CXRs from 30,805 patients were manually checked for foreign objects: vascular port, shoulder endoprosthesis, necklace, and implantable cardioverter-defibrillator (ICD). Then, they were annotated with the use of a computer program, and the necessary image preprocessing was performed, such as resizing, normalization, and cropping. The object detection model was trained using the You Only Look Once v8 architecture and the Ultralytics framework. The results showed not only that the obtained average precision of foreign object detection on the CXR was 0.815 but also that the model can be useful in detecting foreign objects on the CXR images. Models of this type may be used as a tool for specialists, in particular, with the growing popularity of radiology comes an increasing workload. We are optimistic that it could accelerate and facilitate the work to provide a faster diagnosis. Full article

Prosthetic reconstructions provide anatomical reconstruction to replace bones and joints. However, these operations have a high number of short- and long-term complications. One of the main problems in surgery is that the implant remains in the body after the operation. The solution to this problem is to use biomaterial for the implant, but biomaterial does not have the required strength characteristics. The implant must also have a mesh-like structure so that the bone can grow into the implant. The additive manufacturing process is ideal for the production of such a structure. The study deals with the correlation between different prosthetic structures, namely, the relationship between geometry, mechanical properties and biological additivity. The main challenge is to design an endoprosthesis that will mimic the geometric structure of bone and also meet the conditions of strength, hardness and stiffness. In order to match the above factors, it is necessary to develop appropriate algorithms. The main objective of this study is to augment the algorithm to ensure minimum structural weight without changing the strength characteristics of the lattice endoprosthesis of long bones. The iterative augmentation process of the algorithm was implemented by removing low-loaded ribs. A low-loaded rib is a rib with a maximum stress that is less than the threshold stress. Values within the range (10, 13, 15, 16, 17, 18, 19 and 20 MPa) were taken as the threshold stress. The supplement to the algorithm was applied to the initial structure and the designed structure at threshold stresses σ_f = 10, 13, 15, 16, 17, 18, 19 and 20 MPa. A Pareto diagram for maximum stress and the number of ribs is plotted for all cases of the design: original, engineered and lightened structures. The most optimal was the designed “lightweight” structure under the condition σ_f = 17 MPa. The maximum stress was 147.48 MPa, and the number of ribs was 741. Specimens were manufactured using additive manufacturing and then tested for four-point bending. Full article

Background: Expandable distal femur endoprosthesis (EDFE) is commonly used to compensate for the loss of the distal femoral epiphyseal plate in skeletally immature children who have undergone surgical resection of bone malignancies. However, the effect of the passive tibial component of the EDFE on tibial growth has not been extensively studied in the literature. This study aims to delineate the type, frequency, and associated risk factors of multiplanar proximal tibial deformities in skeletally immature children following the use of the expandable distal femur endoprosthesis (EDFE). Moreover, we plan to detect how these deformities influence the long-term functionality of the endoprosthesis in defining the need for subsequent implant revision or further surgical management. Patients and Methods: A total of 20 patients aged (7–12) years underwent expandable distal femur replacement. Two types of implants were used: Juvenile Tumor System (JTS) non-invasive prosthesis in 14 patients, and Modular Universal Tumor and Revision System (MUTARS)^® Xpand Growing Prostheses in six patients. A scanogram and CT scan documented the measurements of longitudinal and multiplanar growth as leg length discrepancy (LLD), femur length discrepancy (FLD), tibia length discrepancy (TLD), and the yield values of rotational, sagittal, and coronal deformities of the tibia. The patients were followed up to assess the need for further management. Sex, age, size of tibial plate perforation, and type of implant used were studied for possible correlation with deformities or growth disturbance. Results: The patients were followed up for a mean of 3 (2–7) years. A total of 14 patients, (10 JTS, 4 implant cast) had a tibial deformity and/or growth disturbance. A single patient was found to have all deformities (growth, rotational, coronal, and sagittal). Fourteen patients were found to have an LLD ranging from 5.3 to 59 mm (median 21 mm), 12 had a TLD from 3 to 30 mm, (median 10 mm), and 11 patients showed evidence of malrotation from 6 to 32 degrees (median 11 degrees). TLD was found to contribute entirely to LLD in three patients, and >50% of LLDs in seven patients. All LLDs were treated conservatively, except in three patients; two received contralateral tibia epiphysiodesis and one received revision with a new implant. A single patient had a posterior tibia slope angle (PTSA) of −2.8 degrees, and three patients had a coronal deformity with a mean medial proximal tibia angle (MPTA) of 80.3 (77–83 degrees). Conclusions: Tibial growth disturbance and multiplanar deformities occur in the majority of patients following EDFE replacement, exacerbating LLD. Yet, these disturbances may be well tolerated, managed conservatively, and rarely mandate endoprosthetic revision or subsequent corrective surgery. Age at the time of surgery was found to be the only significant contributor to the development of tibia growth disturbance. Full article