Background: Displaced transverse patellar fractures require open reduction and internal fixation. State-of-the-art stabilization techniques are tension band wiring (TBW) using Kirschner wires or cannulated screws. These techniques are associated with high rates of secondary fracture displacement, implant migration, implant prominence, wound-healing disturbances, and the need for implant removal. Recently, a locked intraosseous patellar nail prototype was developed. The aim of the present study was to investigate the biomechanical performance of this nail compared with TBW using cannulated screws. Methods: Seven paired fresh-frozen human cadaveric knees were stripped of all soft tissues except the extensor apparatus. A transverse osteotomy was created to simulate an OTA/AO type 34-C1 transverse patellar fracture. The specimen pairs were randomly assigned to be fixed with TBW using cannulated screws or with the new intraosseous nail. Each specimen was cyclically tested for 5,000 cycles by pulling on the quadriceps tendon and simulating active knee extension and passive knee flexion within the range from 90° of flexion to full knee extension. Anterior and articular margin displacement of the fracture as well as interfragmentary rotation around the mediolateral axis were investigated with optical motion tracking after 100, 500, 1,000, 2,500, and 5,000 test cycles. Results: Within the respective 5 testing-cycle time points evaluated, the articular margin displaced on average 68%, 60%, 72%, 76%, and 81% less after intraosseous nailing compared with TBW. Whereas the difference remained nonsignificant after 100 and 500 cycles (p ≥ 0.116), a trend toward significance was observed after 1,000 cycles (p = 0.063), which became significant after 2,500 and 5,000 cycles (p ≤ 0.043). Conclusions: From a biomechanical point of view, the locked intraosseous patellar nail may be an alternative to TBW using cannulated screws because of the higher interfragmentary stability provided at the articular fracture site. Clinical Relevance: A locked patellar nail for transverse patellar fractures achieved a stable osteosynthetic construct that may reduce hardware-associated complications because of its intraosseous positioning.

Background: Patellar fractures are predominantly treated surgically by open reduction and internal fixation using classic tension band osteosynthesis. Biomechanical testing was conducted to examine transverse patellar fracture stabilization using locked intramedullary nail systems in comparison to classic tension band osteosynthesis. Methods: Twenty-four Sawbones ^® with transverse patellar fractures type AO 34-C1.1 were divided equally into three test groups. Three principles for fracture stabilization were used: classical tension band osteosynthesis and newly developed locked intramedullary double nail- and single nail- prototypes. Knee motion (0°/0°/90°) was simulated in a dynamic test set-up using a “single muscle model” by applying tensile forces up to 300 N. The widening and the symmetry of the fracture gap were investigated over 1000 motion cycles using a video-optical system. The significance level was set at α = 0.05 for all statistical evaluations using the Bonferroni–Holm corrected unpaired unilateral t-test and mixed ANOVA with post-hoc Tukey test. Results: The fixation principles showed different maximum fragment displacements of M = 2.04 ± 0.67 mm using classical tension band osteosynthesis, M = 1.34 ± 0.74 mm using intramedullary single nail system and M = 0.55 ± 0.31 mm using intramedullary double nail system. There was a statistically significant change in width of the fracture gap in flexed knee position comparing tension band osteosynthesis and double nail system ( p = 0.0015) and comparing single nail and double nail system ( p = 0.02). Furthermore, the tension-band osteosynthesis showed a significantly greater divergence from symmetry in the fracture gap compared to both intramedullary treatment methods ( p < 0.001). Conclusions: Prototypes of locked intramedullary nail systems showed comparable fixation results for transverse patellar fractures compared to tension band wiring. They showed more symmetrical fracture gap openings during biomechanical testing and offered significantly higher stability to the fragments.

Background: Aseptic loosening remains a leading cause of revision in total hip arthroplasty (THA), with polyethylene wear representing a key contributing factor. Vitamin E–blended highly cross-linked polyethylene (VEPE) has been introduced to improve oxidative stability and long-term wear performance; however, long-term clinical data remain limited. Methods: This retrospective study evaluates long-term polyethylene wear and component positioning in a cohort of patients who underwent primary THA using a vitamin E–blended polyethylene monoblock acetabular component (RM Pressfit vitamys®). Patients were followed for a minimum of ten years. Radiographic assessment was performed using a fully automated, observer-independent CAD-based software (RayMatch®), enabling measurement of cup inclination, anteversion, and polyethylene wear through 2D–3D registration of implant CAD models. Results: A total of 57 hips with complete radiographic follow-up were analyzed. Mean polyethylene wear rates were 26.9 µm/year at five years and 18.2 µm/year at ten years, remaining well below commonly reported thresholds associated with osteolysis. Cup inclination remained stable over time, whereas a gradual increase in measured anteversion was observed during follow-up. Conclusion: At a minimum ten year follow-up, the investigated vitamin E–blended polyethylene monoblock cup demonstrated favorable long-term wear characteristics and stable component positioning. Further comparative studies are warranted to compare its long-term performance with other acetabular cup and liner designs.

Background: Displaced ankle fractures classified as Weber types B and C are common across all age groups. The standard treatment involves open reduction and internal fixation, followed by a rehabilitation program that includes 6 weeks of partial weightbearing. During this period, both passive and active range-of-motion exercises are performed under the supervision of a physiotherapist. Recently, a new device has become available, allowing active controlled motion of the ankle joint at home on top of the normal rehabilitation protocol. The purpose of this controlled randomized trial was to evaluate the superiority of this device as a supplement in standard rehabilitation protocols after distal fibular fractures. Methods: This prospective controlled multicenter trial will include a minimum of 58 patients who have undergone surgical treatment for isolated distal fibular fractures of Weber types B and C. These patients will be randomized into 2 groups: Group 1 will undergo a standardized rehabilitation protocol with active and passive physiotherapy under partial weightbearing for 6 weeks with the active controlled motion device at home on top. Group 2 will receive the same rehabilitation without the device. Three German hospitals with different levels of care and 6 rehabilitation centers are involved in this study. The estimated study duration of 12 months started in October 2024. The follow-up will last 6 months after the recruitment of the last patient. The following assessments are performed: baseline after surgery; after 6 weeks; at 3 and 6 months; and with check-in calls after 2 and 4 weeks. The evaluation of effectiveness is based on FAOS, NRS, and SF-36 scores; changes in employment during the study; return-to-work; return-to-sports; and time-to-unrestricted weightbearing. Discussion: This trial aims to collect valid data to determine whether the use of an active controlled motion device as a supplement to a standardized physiotherapy protocol after surgical treatment of ankle fractures leads to significantly improved outcomes. After evaluation of the results by the German Joint Federal Committee, a final assessment is made to make this device part of a future treatment protocol in the aftercare of surgically treated distal fibular fractures of Weber types B and C. Trial registration: The trial is registered in the International Clinical Trials Registry Platform of the World Health Organization with the Main-ID DRKS00034202 on July 22nd, 2024 (https://trialsearch.who.int/Trial2.aspx?TrialID=DRKS00034202).