Osteosynthesis of high-energy metaphyseal proximal tibia fractures is still challenging, especially in patients with severe soft tissue injuries and/or short stature. Although the use of external fixators is the traditional treatment of choice for open comminuted fractures, patients' acceptance is low due to the high profile and therefore the physical burden of the devices. Recently, clinical case reports have shown that supercutaneous locked plating used as definite external fixation could be an efficient alternative. Therefore, the aim of this study was to evaluate the effect of implant configuration on stability and interfragmentary motions of unstable proximal tibia fractures fixed by means of externalized locked plating. Based on a right tibia CT scan of a 48 years-old male donor, a finite element model of an unstable proximal tibia fracture was developed to compare the stability of one internal and two different externalized plate fixations. A 2-cm osteotomy gap, located 5 cm distally to the articular surface and replicating an AO/OTA 41-C2.2 fracture, was virtually fixed with a medial stainless steel LISS-DF plate. Three implant configurations (IC) with different plate elevations were modelled and virtually tested biomechanically: IC-1 with 2-mm elevation (internal locked plate fixation), IC-2 with 22-mm elevation (externalized locked plate fixation with thin soft tissue simulation) and IC-3 with 32-mm elevation (externalized locked plate fixation with thick soft tissue simulation). Axial loads of 25 kg (partial weightbearing) and 80 kg (full weightbearing) were applied to the proximal tibia end and distributed at a ratio of 80%/20% on the medial/lateral condyles. A hinge joint was simulated at the distal end of the tibia. Parameters of interest were construct stiffness, as well as interfragmentary motion and longitudinal strain at the most lateral aspect of the fracture. Construct stiffness was 655 N/mm (IC-1), 197 N/mm (IC-2) and 128 N/mm (IC-3). Interfragmentary motions under partial weightbearing were 0.31 mm (IC-1), 1.09 mm (IC-2) and 1.74 mm (IC-3), whereas under full weightbearing they were 0.97 mm (IC-1), 3.50 mm (IC-2) and 5.56 mm (IC-3). The corresponding longitudinal strains at the fracture site under partial weightbearing were 1.55% (IC-1), 5.45% (IC-2) and 8.70% (IC-3). From virtual biomechanics point of view, externalized locked plating of unstable proximal tibia fractures with simulated thin and thick soft tissue environment seems to ensure favorable conditions for callus formation with longitudinal strains at the fracture site not exceeding 10%, thus providing appropriate relative stability for secondary bone healing under partial weightbearing during the early postoperative phase

Abstract. Objective. To compare the clinical and radiological outcome between less invasive stabilization system (LISS, Synthes, Paoli, PA.) and open reduction with internal fixation (ORIF) for the treatment of extraarticular proximal tibia fractures through the lateral approach. Background. Proximal tibial fractures present a difficult treatment challenge with historically high complication rates. ORIF has been in vogue for long time with good outcome. But these are associated with problems especially overlying skin conditions, delayed recovery and rehabilitation with limited functional outcome. LISS is an emerging procedure for the treatment of proximal tibial fractures. It preserves soft tissue and the periosteal circulation, which promotes fracture healing. Patients and methods. Thirty patients with closed proximal tibial fractures were included in this study. They were randomly divided into 2 groups. Group I (n=15) patients were treated by LISS and group II (n=15) by ORIF. Major characteristics of the two groups were similar in terms of age, sex, mode of injury, fracture location, and associated injuries. All patients were followed up at least 6 months. Results. In each group, 12 patients were united, 2 patients were non- united and one patient showed delayed union. The mean operative time in LISS patients was 79.3 min, while in ORIF patients; it was 122 min. All patients of LISS group were exposed to radiation, while only 40% of ORIF group were exposed. The mean time of union of LISS patients was 10.87weeks. While in ORIF patients, the mean time of union was 21.13 weeks. There was no significant difference between both groups regarding the postoperative complications. Functional outcome was satisfactory in both groups. Conclusion. LISS achieves comparable results with ORIF in extraarticular fractures of the proximal tibia. Although LISS potentially has the radiation hazard, it reduces the perioperative complications with a shortened operation time and minimal soft tissue dissection. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project