Background: Patellar fractures have a comparatively low incidence compared to all fracture frequencies of the musculoskeletal system. However, surgical management is crucial to prevent postoperative complications that affect the knee joint. The purpose of the present study was to evaluate the incidence of postoperative complications and onset of postoperative osteoarthritis related to the chosen technique of patellar fracture management. Methods: In a retrospective cohort study consecutive managed, isolated patella fractures were reviewed for demographic data, trauma mechanism, patella fracture type, fixation technique and postoperative complications. The results were documented radiographically and clinically and analysed statistically. The reporting followed the STROBE guidelines. Results: A total of 112 patients were eligible for data evaluation. Surgical management of comminuted patellar fractures with small fragment screws showed significant fewer postoperative complications compared to other fixation techniques (8%, p < 0.043). The incidence of posttraumatic infection was significantly higher following the hybrid fixation technique with cannulated screws and tension wire than following the other analysed techniques (p = 0.024). No postoperative wound infection was observed after screw fixation or locking plate fixation. Symptomatic hardware was most frequently seen after tension-band fixation. Onset of posttraumatic osteoarthritis was most often found after the hybrid fixation technique (55%). Conclusion: Surgical management of patellar fractures remains crucial but fracture fixation using plating systems or small fragment screws is least associated with postoperative complications. Trial registration: Trial registration number (DRKS):00027894.

Introduction: Hoffa fractures are a rare and often overlooked entity. The main goal of surgical treatment is to restore the articular surface and maintain knee function. However, current clinical data indicate heterogeneous outcomes. The aim of this multicenter study was to obtain a representative data set of patients with isolated Hoffa fractures with special emphasis on concomitant soft tissue injuries, diagnostic algorithms, treatment strategies and functional outcomes. Materials and methods: Participating Level I trauma centres were asked to review their internal database for isolated Hoffa fractures treated surgically between 2010 and 2020. Demographics, mechanism of injury, diagnostic and therapeutic algorithm, Letenneur classification, concomitant soft tissue injuries, and postoperative knee function and complications were analysed. Results: A total of 56 patients from six participating trauma centres were included. The median age at injury was 45 years (15–94) with a median follow-up of 19 months (2–108). The most common mechanism of injury was high-energy trauma, with unicondylar lateral Letenneur type I and II fractures being the most common. Surgical treatment was independent of the type of fracture and included isolated screw fixation, combined plate and screw fixation and isolated plate osteosynthesis. Isolated screw fixation resulted in significantly better range of motion (ROM) values (p = 0.032), but the highest number of postoperative complications (n = 14/20, n.s.) compared to the other fixation techniques. The highest number of fixation failures requiring revision was observed in the plate and screw fixation group (n = 3/8, p = 0.008). Osteochondral flake fractures (n = 12/43, 27%) and lateral meniscus injuries (n = 5/49, 10%) were commonly seen in Hoffa fractures. Conclusions: Treatment of Hoffa fractures with screw fixation resulted in significantly better functional outcomes, probably due to less comminuted fractures. Concomitant cartilage, meniscal and ligamentous injuries are common and warrant preoperative recognition and management.

Background: The number of total knee replacements performed annually is steadily increasing. Parallel options for postoperative care are decreasing, which reduces patient satisfaction. External devices to support physical rehabilitation and health monitoring will improve patient satisfaction and postoperative care. Methods: In a prospective, international multicenter study, patients were asked to use an external motion sensor and a smartphone application during the postoperative course of primary total knee arthroplasty. The collected data were transferred to a data platform, allowing for the real-time evaluation of patient data. Results: In three participating centers, 98 patients were included. The general acceptance of using the sensor and app was high, with an overall compliance in study participation rate of up to 76%. The early results showed a significant improvement in the overall quality of life (p < 0.001) and significant reductions in pain (p < 0.01) and depression (p < 0.001). Conclusions: The early results of this clinical and multicenter study emphasize that there is a high interest in and acceptance of digital solutions in patients’ treatment pathways. Motion sensor and smartphone applications support patients in early rehabilitation.