The main purpose of this retrospective study was to evaluate how many intraarticular soft tissue lesions were revealed by arthroscopic monitoring among 75 patients with fractures of the knee that had been stabilized by minimally invasive techniques. Specifically, the fractures affected the tibial plateu in 39 cases, the eminential intercondylica in 15, the patella in 17, and the femoral condyle in 4. We found that 15 patients with tibial plateau fractures, 5 with fractures of the eminentia intercondylica, 9 with fractures of the patella and 1 with a fracture of the distal femur had intraarticular lesions that were important for the intraoperative and postoperative therapy. Preoperative MRI was performed in 21 patients. In 10 patients we found differences between the radiological and the arthroscopical findings. In 5 patients the radiological examinations failed to disclose lesions of the meniscus and the anterior cruciate ligament, all of which had implications for the therapy. On the basis of our own results and with reference to the literature, we recommend arthroscopy for examination of fractures of the eminentia intercondylica and of selected fractures of the tibial plateau, the patella and the femoral condyles, owing to the high rate of intaarticular lesions.