[Post-traumatic hemarthrosis of the knee joint--determination of the cause by arthroscopy (author's transl)].

Between December 1977 and February 1981, a series of 70 patients was examined because of an unclear hemarthrosis, the source of hemorrhage was determined by arthroscopy. In our opinion a hemarthros of the knee joint is not clear if the lateral ligaments are stable, no drawer can be loosened at an angle of 90 degrees, and if the X-ray radiograph does not clearly show a fresh fracture. In most cases, the symptom of uncertain hemarthros was provoked by a banal trauma hardly to reconstruct. Due to the violent pain caused by the thick effusion, the patients consulted the doctor early and had partly been pre-examined by several doctors. In all cases, the joint was described to possess stable ligaments and X-ray examination did not show any clear fracture sign. The thorough examination under anesthesia made by the author resulted in a suspicion of a ligament in 43% of the examined joints, however, the subsequent arthroscopy showed a rupture of the anterior cruciate ligament in 70%. A cartilage/bone lesion was found in 30%, a rupture of the posterior cruciate ligament, however, only in 5,7%. In two cases (3%), the hemorrhage was caused by a fatty body lesion or the rupture of an adhesion. In 41% of the patients we found severe combined lesions of the anterior cruciate ligament and the meniscus or cartilage lesions. In 56 patients, i.e. 80%, the lesion was so severe that they had to be treated by surgery. In 11%, we thought an immobilization by plaster cast to be sufficient. Only six patients i.e. 9%, had neither to be operated nor immobilized. The hemarthros of the knee joint which occurs even after small accidents is caused by severe inner lesions of ligaments and cartilages. In more than 50% of all cases, these lesions cannot be diagnosed even by careful clinical examination under anesthesia and special X-ray examination methods. With adequate skill and experience, however, arthroscopy allows an exact diagnosis in almost 100% of all cases. It is therefore the patient's interest to clarify by arthroscopy every case of unclear hemarthrosis.