Total knee arthroplasty (TKA) with modern all-polyethylene tibial (APT) components has shown high long-term survival rates and comparable results to those with metal-backed tibial components. Nevertheless, APT components are primarily recommended for older and low-demand patients. There are no evidence-based biomechanical guidelines for orthopaedic surgeons to determine the appropriate lower age limit for implantation of APT components. A biomechanical analysis was assumed to be suitable to evaluate the clinical results in patients under 70 years. The scope of this study was to determine biomechanically the appropriate lower age limit for implantation of APT components. To generate data of the highest possible quality, the geometry of the computational models was created based on computed tomography (CT) images of a representative patient. The cortical bone tissue model distinguishes the change in mechanical properties described in three parts from the tibial cut. The cancellous bone material model has a heterogeneous distribution of mechanical properties. The values used to determine the material properties of the tissues were obtained from measurements of a CT dataset comprising 45 patients. Computational modeling showed that in the majority of the periprosthetic volume, the von Mises strain equivalent ranges from 200 to 2700 με; these strain values induce bone modeling and remodeling. The highest measured deformation value was 2910 με. There was no significant difference in the induced mechanical response between bone models of the 60-year and 70-year age groups, and there was <3% difference from the 65-year age group. Considering in silico limitations, we suggest that APT components could be conveniently used on a bone with mechanical properties of the examined age categories. Under defined loading conditions, implantation of TKA with APT components is expected to induce modeling and remodeling of the periprosthetic tibia. Following clinical validation, the results of our study could modify the indication criteria of the procedure, and lead to more frequent implantation of all-polyethylene TKA in younger patients.

Purpose: This study aims to compare total knee replacement (TKA) with NexGen All-Poly (APT) and NexGen Metal-Backed (MBT) in terms of implant survivorship, reasons leading to implant failure and functional results of defined age categories. Methods: A single-centre, retrospective evaluation of 812 patients who underwent knee replacement with NexGen CR between 2005 and 2021, comparing a modern congruent APT component to a modular MBT equivalent component using a similar surgical technique at a notable mean follow-up duration. Implant survival, functional outcomes using the Knee Society Score and range of motion were evaluated and compared in different age categories. Results: Of the 812 NexGen CR TKAs performed at our institution, 410 (50.4%) used APT components and 402 (49.6%) MBT components. The survival rate of NexGen APT was 97.1% and that of NexGen MBT was 93.2% (p = 0.36). Removal of the implant occurred overall in 15 cases, for MBT in ten cases, and for APT in four cases. The FS was proved to be significantly higher when APT components were implanted in younger patients than for MBT (p = 0.005). A similar range of motion between the components was recorded (p = 0.1926). Conclusion: Under defined conditions, we measured the clinical results of implants from a single manufacturer implanted in a single department using a similar surgical technique. Considering the limitations, we suggest that all-polyethylene tibial components are equal or even superior to metal-backed ones across the examined age categories.

Joint Diseases and Related Surgery (JDRS), the official journal of the Turkish Joint Diseases Foundation, is an international, peer-reviewed, immediate open access journal. All published articles in JDRS has been free for everyone, without embargo, since 1990.

Purpose: Subpectoral biceps tenodesis is a widely used surgical technique to relieve pain and restore function in the shoulder by securing the long head of the biceps tendon. This study aimed to evaluate the mechanical performance of three fixation techniques using cortical button, interference screw and keyhole methods by assessing their strength, durability and strain distribution, incorporating the novel application of digital image correlation (DIC). Methods: Thirty fresh porcine bone‐tendon specimens were allocated evenly among the fixation techniques. Biomechanical testing involved cyclic axial loading (10–100 N) for 500 cycles, followed by load‐to‐failure testing using a universal testing machine. DIC analysis assessed strain distribution around the bone drill site. Statistical comparisons of displacement, load‐to‐failure and strain patterns were performed. Results: Cortical button fixation demonstrated the highest average load‐to‐failure at 353 ± 45 N, with all specimens completing 500 cycles and showing the least variability. In comparison, interference screw fixation had the lowest average load‐to‐failure (271 ± 71 N) with two failures occurring before 500 cycles, and the keyhole technique showed intermediate performance at 319 ± 45 N, also with two early failures. Cyclic displacement after 500 cycles was lowest for the interference screw (3.16 ± 0.52 mm), followed by the keyhole (11.51 ± 2.08 mm), and highest for the cortical button (13.84 ± 1.90 mm). Displacement range after 500 cycles was also lowest in the interference screw group (0.62 ± 0.05 mm), compared to the cortical button (0.88 ± 0.07 mm) and keyhole (0.91 ± 0.23 mm). DIC revealed the highest maximum first principal strain around cortical button fixation (0.21%), followed by interference screw (0.16%) and keyhole (0.13%). Conclusion: Cortical button fixation demonstrated the highest load‐to‐failure and the lowest variability, indicating mechanical reliability. The interference screw and keyhole techniques showed comparable load‐to‐failure values and cyclic displacement but exhibited greater variability. DIC analysis revealed higher localized strain around the cortical button fixation, whereas the interference screw and keyhole techniques displayed more evenly distributed strain. Level of Evidence: Level V.

Elbow tumors, though rare, pose significant reconstructive challenges due to the joint's complex anatomy and limited soft tissue coverage. This study evaluates the functional outcomes, complications, and implant survival rates of modern-design elbow tumor endoprostheses following resection of distal humerus or proximal ulna tumors. Conducted across 2 tertiary sarcoma centers, the retrospective study analyzed 18 patients treated from 2014 to 2023. Patients underwent primary surgery with consistent surgical and postoperative protocols. The study evaluated implant survival, complications, and functional outcomes following elbow tumor resection and endoprosthetic reconstruction, using Musculoskeletal Tumor Society score, the Toronto Extremity Salvage Score, and the Modified Elbow Performance Score, and range of motion measurements. Factors influencing implant failure, including resection location, bone length, prosthesis type, allograft use, and fixation method, were also analyzed. Implant survival rates were 94%, 86%, and 65% at 1, 3, and 5 years, respectively, with cemented fixation showing lower survival at 5 years compared to uncemented fixation. Intraoperative complications included 3 transient nerve injuries and one humeral fracture, while postoperative complications, classified by the Henderson system, led to 9 revisions in 7 patients. The mean Musculoskeletal Tumor Society, Toronto Extremity Salvage Score, and Modified Elbow Performance Score scores were 78.7% (23.6 ± 2.9), 75.4% (±8.9), and 82.2% (±9.4), respectively, with no significant differences between humeral and ulnar resections. Patients achieved a mean maximum elbow flexion of 115.26 ± 16.8° and an overall mean range of motion exceeding 100°. In this national study, elbow endoprosthetic reconstruction after tumor resection was associated with acceptable functional outcomes and a 65% 5-year implant survival rate, though revision surgery was required in nearly 40% of patients. While permanent neurological deficits were rare, the complication burden underscores the need for cautious patient selection and long-term follow-up.